• •

June 2002 • NREL/TP-510-32438

Lignocellulosic Biomass to

Ethanol Process Design and

Economics Utilizing Co-Current

Dilute Acid Prehydrolysis and

Enzymatic Hydrolysis for

Corn Stover

A. Aden, M. Ruth, K. Ibsen, J. Jechura, 

K. Neeves, J. Sheehan, and B. Wallace 

National Renewable Energy Laboratory 

L. Montague, A. Slayton, and J. Lukas

Harris Group

Seattle, Washington

National Renewable Energy Laboratory 

1617 Cole Boulevard 

Golden, Colorado 80401-3393 

NREL is a U.S. Department of Energy Laboratory

Operated by Midwest Research Institute • Battelle • Bechtel 

Contract No. DE-AC36-99-GO10337 
• •

June 2002 • NREL/TP-510-32438

Lignocellulosic Biomass to

Ethanol Process Design and

Economics Utilizing Co-Current

Dilute Acid Prehydrolysis and

Enzymatic Hydrolysis for

Corn Stover

A. Aden, M. Ruth, K. Ibsen, J. Jechura, 

K. Neeves, J. Sheehan, and B. Wallace 

National Renewable Energy Laboratory 

L. Montague, A. Slayton, and J. Lukas

Harris Group

Seattle, Washington

Prepared under Task No. BFP2.A410 

National Renewable Energy Laboratory 

1617 Cole Boulevard 

Golden, Colorado 80401-3393 

NREL is a U.S. Department of Energy Laboratory

Operated by Midwest Research Institute • Battelle • Bechtel 

Contract No. DE-AC36-99-GO10337 
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Abstract 

The U.S. Department of Energy (DOE) is promoting the development of ethanol from 

lignocellulosic feedstocks as an alternative to conventional petroleum-based transportation fuels. 

DOE funds both fundamental and applied research in this area and needs a method for predicting 

cost benefits of many research proposals. To that end, the National Renewable Energy 

Laboratory (NREL) has modeled many potential process designs and estimated the economics of 

each process during the last 20 years. 

This report is an update of the ongoing process design and economic analyses at NREL. We 

envision updating this process design report at regular intervals; the purpose being to ensure that 

the process design incorporates all new data from NREL research, DOE funded research and 

other sources, and that the equipment costs are reasonable and consistent with good engineering 

practice for plants of this type. For the non-research areas this means using equipment and 

process approaches as they are currently used in industrial applications. 

For the last report1

, published in 1999, NREL performed a complete review and update of the 

process design and economic model for the biomass-to-ethanol process utilizing co-current dilute 

acid prehydrolysis with simultaneous saccharification (enzymatic) and co-fermentation. The 

process design included the core technologies being researched by the DOE: prehydrolysis, 

simultaneous saccharification and co-fermentation, and cellulase enzyme production. In addition, 

all ancillary areas—feed handling, product recovery and purification, wastewater treatment 

(WWT), lignin combustor and boiler-turbogenerator, and utilities—were included. NREL 

engaged Delta-T Corporation (Delta-T) to assist in the process design evaluation, the process 

equipment costing, and overall plant integration. The process design and costing for the lignin 

combustor and boiler turbogenerator was reviewed by Reaction Engineering Inc. (REI) and 

Merrick & Company reviewed the wastewater treatment. 

Since then, NREL has engaged Harris Group (Harris) to perform vendor testing, process design, 

and costing of critical equipment identified during earlier work. This included solid/liquid 

separation and pretreatment reactor design and costing. Corn stover handling was also 

investigated to support DOE’s decision to focus on corn stover as a feedstock for lignocellulosic 

ethanol. Working with Harris, process design and costing for these areas were improved through 

vendor designs, costing, and vendor testing in some cases. In addition to this work, enzyme costs 

were adjusted to reflect collaborative work between NREL and enzyme manufacturers (Genencor 

International and Novozymes Biotech) to provide a delivered enzyme for lignocellulosic 

feedstocks. This report is the culmination of our work and represents an updated process design 

and cost basis for the process using a corn stover feedstock. 

The process design and economic model are useful for predicting the cost benefits of proposed 

research. Proposed research results can be translated into modifications of the process design, 

and the economic impact can be assessed. This allows DOE, NREL, and other researchers to set 

priorities on future research with an understanding of potential reductions to the ethanol 

production cost. 

To be economically viable, ethanol production costs must be below market values for ethanol. 

DOE has chosen a target ethanol selling price of $1.07 per gallon as a goal for 2010. The 

conceptual design and costs presented here are based on a 2010 plant start-up date. The key 

research targets required to achieve this design and the $1.07 value are discussed in the report. 

i 
Table of Contents 

I. Introduction..............................................................................................................1 

I.1 Approach..................................................................................................................3

I.2 Process Overview.....................................................................................................5 

I.3 Plant Size .................................................................................................................7 

I.3.1 Effect of Plant Size on Collection Distance.............................................................7 

I.3.2 Estimating Corn Stover Costs Today.....................................................................10 

I.3.3 Effect of Distance on Stover Cost..........................................................................11 

I.3.4 Cost of Ethanol as a Function of Plant Size...........................................................12 

I.3.5 Selecting the Right Plant Size................................................................................15 

I.4 Feedstock and its Composition ..............................................................................16 

II. Processing Design and Cost Estimating ................................................................18 

II.1 Feedstock Storage and Handling – Area 100 (PFD-P110-A101)..........................18 

II.1.1 Overview................................................................................................................18 

II.1.2 Design Basis...........................................................................................................18 

II.1.3 Cost Estimation......................................................................................................20 

II.2 Pretreatment and Hydrolyzate Conditioning – Area 200 (PFD-P110-A201-3).....20 

II.2.1 Overview................................................................................................................20 

II.2.2 Design Basis...........................................................................................................22 

II.2.3 Cost Estimation......................................................................................................24 

II.2.4 Achieving the Design Case....................................................................................26 

II.3 Saccharification and Co-Fermentation – Area 300 (PFD-P110-A301-2)..............27 

II.3.1 Overview................................................................................................................27 

II.3.2 Design Basis...........................................................................................................28 

II.3.3 Cost Estimation......................................................................................................33 

II.3.4 Achieving the Design Case Targets.......................................................................34 

II.4 Cellulase Enzyme...................................................................................................36 

II.5 Product, Solids, and Water Recovery (Distillation, Dehydration, Evaporation, 

and Solid-Liquid Separation) – Area 500 (PFD-P110-A501-5).......................36 

II.5.1 Overview................................................................................................................36 

II.5.2 Design Basis Description.......................................................................................38 

II.5.3 Cost Estimation......................................................................................................39 

II.6 Wastewater Treatment – Area 600 (PFD-110-A601-2).........................................40 

II.6.1 Overview................................................................................................................40 

II.6.2 Design Basis...........................................................................................................42 

II.6.3 Cost Estimation......................................................................................................44 

II.7 Product and Feed Chemical Storage – Area 700 (PFD-P110-A701) ....................45 

II.7.1 Overview................................................................................................................45 

II.7.2 Design Basis...........................................................................................................45 

II.7.3 Cost Estimation......................................................................................................46 

II.8 Combustor, Boiler, and Turbogenerator – Area 800 (PFD-P110-A801-3) ...........46 

II.8.1 Overview................................................................................................................46 

II.8.2 Design Basis...........................................................................................................47 

II.8.3 Cost Estimation......................................................................................................49 

II.9 Utilities – Area 900 (PFD-P110-A901-3)..............................................................50 

ii 
II.9.1 Overview................................................................................................................50 

II.9.2 Design Basis...........................................................................................................50 

II.9.3 Cost Estimation......................................................................................................52 

II.10 Water and Carbon Balances and Energy Analysis ................................................52 

II.10.1 Water Balance........................................................................................................52

II.10.2 Carbon Balance......................................................................................................53 

II.10.3 Energy Analysis.....................................................................................................56 

III. Process Economics.................................................................................................60 

III.1 Analysis Procedure ................................................................................................60 

III.1.1 Total Project Investment ........................................................................................60 

III.1.2 Variable Operating Costs.......................................................................................64 

III.1.3 Fixed Operating Costs............................................................................................65 

III.1.4 Discounted Cash Flow Analysis and the Selling Cost of Ethanol.........................66 

III.1.5 The Cost of Sugar ..................................................................................................71 

IV. Sensitivity Analysis ...............................................................................................72 

IV.1 Stover Composition, Cost, and Handling ..............................................................72 

IV.2 Pretreatment Yields and Cost.................................................................................73 

IV.3 Gypsum ..................................................................................................................73

IV.4 Saccharification and Fermentation Yields and Cost..............................................74 

IV.5 Energy Production .................................................................................................77 

IV.6 Monte Carlo Analysis ............................................................................................78 

IV.6.1 Overview................................................................................................................78 

IV.6.2 Parameter Estimates...............................................................................................79 

IV.6.3 Results....................................................................................................................80 

V. Planned Improvements and Extensions to the Model............................................82 

V.1 Water Balance and Optimization...........................................................................82 

V.2 Fermentation pH Control .......................................................................................82 

V.3 Air Emissions.........................................................................................................82 

V.4 Greenhouse Gas Emissions....................................................................................82 

V.5 Lignin Gasification and Gas Turbine Power Generation.......................................83 

V.6 Physical Properties of Corn Stover........................................................................83 

References and Notes.........................................................................................................83

Appendix A – NREL Biofuels Process Design Database Description and Summary

Appendix B – Individual Equipment Costs Summary

Appendix C – Chemical Costs and Sources 

Appendix D – Discounted Cash Flow Rate of Return Summary

Appendix E – Process Parameters 

Appendix F – Process Flow Diagrams (PFDs) 

Appendix G – Changes from the 1999 Design Report 

Appendix H – Chemical Formulas for Biomass Compounds 

Appendix I – Physical Property Model and Parameters for Distillation 

iii 
Figures 

Figure 1. NREL’s Approach to Process Design and Economic Analysis......................3 

Figure 2. Overall Process, PFD-P100-A000 ..................................................................6 

Figure 3. GIS Model Results Showing the Location of 35 2000 MT/d Ethanol 

Plants in Iowa.............................................................................................8 

Figure 4. The Effect of Plant Size on Collection Distance ............................................9 

Figure 5. Typical Breakdown of Corn Stover Costs ....................................................10 

Figure 6. Hauling Charges for Corn Stover as a Function of Distance........................12 

Figure 7. Ethanol Cost as a Function of Plant Size for 10% Availability of Corn

Acres ........................................................................................................13 

Figure 8. Ethanol Price as a Function of Plant Size and Percentage of Available 

Acres ........................................................................................................14 

Figure 9. Ethanol Price as a Function of Plant Size and Hauling Cost ($/ton-mile)....15 

Figure 10. Pretreatment Process Area Overview, PFD-P100-A200 ..............................21 

Figure 11. Corrosion Resistance of Incoloy 825............................................................25 

Figure 12. Distillation System Overview, PFD-P110-A500..........................................37 

Figure 13. Wastewater Treatment (WWT) Process Overview, PFD-P110-A600 .........41 

Figure 14. Process Carbon Balance................................................................................55 

Figure 15. Process Energy Analysis Based on Higher Heating Value of Biomass Feed58 

Figure 16. CFBC/Turbogenerator Energy Balance........................................................60 

Figure 17. Effect of Varying IRR and Equity on Minimum Ethanol Selling Price .......67 

Figure 18. Cost Contribution Details from Each Process Area......................................71 

Figure 19. SSF Yields for Multiple Enzyme Loadings........................................................75 

Figure 20. MESPs for Multiple Enzyme Loadings...................................................................76 

Figure 21. MESPs for Multiple Residence Times ....................................................................76

Figure 22. Histogram of the Minimum Ethanol Selling Price .......................................80 

Figure 23. Probability Curve of the Minimum Ethanol Selling Price............................81 

Figure 24. Histogram of the Total Project Investment...................................................81 

iv 
Tables 

Table 1. Feedstock Composition.................................................................................16 

Table 2. Measured Stover Composition Ranges.........................................................17 

Table 3. Pretreatment Hydrolyzer Conditions ............................................................22 

Table 4. Pretreatment Hydrolyzer Reactions and Conversions ..................................23 

Table 5. Experimental Pretreatment Reactor Conditions............................................26 

Table 6. Experimental Pretreatment Hydrolyzer Reactions and Conversions............26 

Table 7. Saccharification Conditions..........................................................................29 

Table 8. Saccharification Reactions and Conversions................................................29 

Table 9. Seed Train Specifications .............................................................................30 

Table 10. Seed Train Reactions and Conversions.........................................................31 

Table 11. Co-Fermentation Conditions.........................................................................32 

Table 12. Co-Fermentation Reactions and Conversions...............................................32 

Table 13. Co-Fermentation Contamination Loss Reactions .........................................33 

Table 14. Experimental Saccharification Conditions ...................................................34 

Table 15. Experimental Saccharification Reactions and Conversions .........................34 

Table 16. Experimental Co-Fermentation Conditions ..................................................35 

Table 17. Experimental Co-Fermentation Reactions and Conversions ........................35 

Table 18. Comparison of Sending Evaporator Syrup to the Combustor or WWT .......44 

Table 19. Boiler Costs...................................................................................................49 

Table 20. Ethanol Plant Overall Water Balance ...........................................................53 

Table 21. Ethanol Plant Overall Carbon Balance .........................................................54 

Table 22. Feed Stream Carbon Composition................................................................56 

Table 23. Ethanol Plant Overall Energy Analysis ........................................................57 

Table 24. Feed Stream Energy Analysis.......................................................................59 

Table 25. Installation Factors........................................................................................62 

Table 26. Chemical Engineering Purchased Equipment Index ....................................62 

Table 27. Additional Cost Factors for Determining Total Project

Investment................................................................................................63 

Table 28. Total Installed Equipment Costs...................................................................63 

Table 29. Total Project Investment (TPI) .....................................................................64 

Table 30. Variable Operating Costs..............................................................................64 

Table 31. Inorganic Chemical Index.............................................................................65 

Table 32. Fixed Operating Costs...................................................................................66 

Table 33. Labor Index...................................................................................................66 

Table 34. Construction Activities and Cash Flow ........................................................69 

Table 35. Discounted Cash Flow Parameters ...............................................................70 

Table 36. Summary of Yields, Rates and Conversion Costs ........................................70 

Table 37. Mixed Sugar Stream Concentration from Saccharification..........................72 

Table 38. Effect of Pretreatment Yields on Minimum Ethanol Selling Price...............73 

Table 39. Summary of Sensitivity Results by Cost Impact ..........................................78 

Table 40. Input Parameter Distribution for Monte Carlo Analysis...............................79 

v 
Acronyms 

ABB ABB Power Generation Systems 

ACFM Actual Cubic Feet per Minute 

ASPEN Advanced Simulator for Process Engineering 

ANSI American National Standards Institute 

API American Petroleum Institute 

BFW Boiler Feed Water 

B/MAP Biomass AgriProducts 

BOD Biochemical Oxygen Demand 

BTU British Thermal Unit 

CFBC Circulating Fluidized Bed Combustor 

CFM Cubic Feet per Minute 

CIP Clean-in-place 

COD Chemical Oxygen Demand 

CS Carbon Steel 

CSL Corn Steep Liquor 

CW Cooling Water 

DAP Diammonium Phosphate 

DB Declining Balance 

DOE U.S. Department of Energy 

EIA Energy Information Administration 

EPA Environmental Protection Agency 

EtOH Ethanol 

FPU Filter Paper Units 

FWE Foster Wheeler Energy 

GDS General Depreciation System 

GIS Geographic Information System 

GPM Gallons per minute 

HHV Higher Heating Value 

HMF Hydroxymethyl Furfural 

IFPU International Filter Paper Units (see FPU) 

IGCC Integrated Gasification Combined Cycle 

IRR Internal Rate of Return 

IRS Internal Revenue Service 

LHV Lower Heating Value 

MACRS (IRS) Modified Accelerated Cost Recovery System 

MESP Minimum Ethanol Selling Price 

MM Million 

MT Metric Ton 

NREL National Renewable Energy Laboratory 

NSPS New Source Performance Standards 

ORNL Oak Ridge National Laboratory 

P&ID Piping and Instrument Diagram 

PDU Process Development Unit 

vi 
PFD Process Flow Diagram 

REI Reaction Engineering, Inc. 

SCFM Standard Cubic Feet per Minute 

SS Stainless Steel

SSCF Simultaneous Saccharification and Co-Fermentation 

ST Short Ton 

TPI Total Project Investment

VOC Volatile Organic Compound 

WWT Wastewater Treatment

vii 
I. Introduction 

The U.S. Department of Energy (DOE) is promoting the development of ethanol from 

lignocellulosic feedstocks as an alternative to conventional petroleum transportation fuels. 

Programs being sponsored by DOE range from fundamental and applied research for developing 

better cellulose hydrolysis enzymes and ethanol-fermenting organisms, to engineering studies of 

potential processes, to co-funding initial biomass-to-ethanol demonstration and production 

facilities. This research is being conducted by various national laboratories, including the 

National Renewable Energy Laboratory (NREL) and Oak Ridge National Laboratory (ORNL), as 

well as by universities and private industry. Engineering and construction companies and 

operating companies are generally conducting the engineering work. 

There are two primary reasons for NREL to investigate the complete process design and 

economics of lignocellulosic ethanol plants. First, this effort helps to direct research by 

developing a benchmarking case for the current conceptual process design. Once the benchmark 

case is developed, the proposed research and its anticipated results are translated into a new 

design, the economics (the anticipated results of proposed research) are determined, and this new 

information is compared to the benchmark case. Following this process for several proposed 

research projects allows DOE to make funding decisions based on which projects have the 

greatest potential to lower the cost of ethanol production. Complete process design and 

economics are required for such studies because a new proposal in one research area may have a 

large effect on another process area that is not generally part of the research program, such as 

product recovery or waste treatment. The impact on other areas of the process can have a 

significant impact on the economics of the proposed research. 

Second, this investigation allows us to develop an absolute cost of the production of ethanol 

based on process and plant design assumptions. In reviewing and establishing research directions, 

only relative cost differences are important. However, to be able to compare the economics of 

ethanol with other fuels, the absolute cost is required. An absolute cost is also needed to study 

the potential ethanol market penetration of the lignocellulosic biomass to ethanol process. Thus, 

we are making the best possible attempt to develop cost estimates that are consistent with 

applicable engineering, construction, and operating practices for facilities of this type. To do so, 

the complete process, including newly researched areas and industry-available process 

components must be designed and their costs determined. For the current level of design 

knowledge, we consider the capital cost estimate to be at the conceptual level. 

To improve the plant cost estimates that affect the absolute cost of ethanol production, NREL 

contracts with companies such as Harris Group (Harris) and Delta-T Corporation (Delta-T) to 

assist in preparing, reviewing, and estimating costs for the process designs. Delta-T worked with 

NREL process engineers in 1998-99 to review all the process design and equipment costs (with 

the exclusion of wastewater treatment and the combustor-boiler system, which were reviewed by 

Merrick Engineering2

 and Reaction Engineering, Inc.3 [REI], respectively). At the conclusion of 

these efforts, the first design report was published1

. 

As a result of the NREL/Delta-T work, several areas were identified that required more extensive 

study. Therefore, NREL worked with Harris to perform vendor testing, corrosion testing, process 

design, and costing of critical equipment identified from the earlier work. This included 

solid/liquid separation equipment and pretreatment reactors. Corn stover handling was also 

investigated to support DOE’s decision to focus on stover in its efforts to commercialize 

lignocellulosic ethanol. Working with Harris, process design and costing for these areas was 

1 
improved. At the same time, DOE partnered with the two largest enzyme manufacturers in the 

world (Genencor International and Novozymes Biotech) to reduce the cost of cellulase enzymes 

by a factor of 10. It is assumed that these companies will produce the enzymes and sell them to 

ethanol producers. Therefore, the ethanol plant will no longer be responsible for enzyme 

production but will purchase them from off-site. This report is the culmination of this work and 

represents an updated process design and cost basis for the process using a corn stover feedstock. 

To be economically viable, ethanol production costs must be below market values for ethanol. 

DOE has chosen a target ethanol selling price of $1.07 per gallon as a goal for 2010. The 

conceptual design and costs presented here are based on a 2010 plant start-up date. The key 

research targets required to achieve this design and the $1.07 value are discussed in the report. 

We envision that this conceptual process design will be updated via an on-going process, and that 

reports will be released at regular intervals. The purpose is to ensure that the process design 

incorporates all new data from NREL research, DOE funded research and other sources, and that 

the equipment costs are reasonable and consistent with good engineering practice for plants of 

this type. For the non-research areas this means using equipment and process approaches as they 

are currently being used in industrial applications. 

2 
I.1 Approach 

Developing a model that describes the chemical conversion process and its economics requires 

information from many different arenas. Figure 1 describes the approach used here for modeling 

the conversion of biomass to ethanol. 

Rigorous Material & 

Energy Balance 

ASPEN Plus Software 

Engineering Co. Consulting 

on Process Configuration 

DOE/NREL Sponsored 

Research Results 

Outside Engineering 

Studies, e.g., Feed 

Handling, Separations 

Capital & Project 

Cost Estimation 

Discounted Cash Flow 

Economic Model 

ICARUS 

Cost Estimation 

Software 

Vendor Equipment 

Cost Quotations 

Engineering Co. 

Cost Estimations 

Minimum Ethanol 

Selling Price 

Process Flow Diagrams 

Estimates of Other 

Commercial Technology 

Figure 1. NREL's Approach to Process Design and Economic Analysis 

The first step to any conceptual process design is to develop a set of process flow diagrams 

(PFDs). Appendix F contains the PFDs developed for this study. Using the arrangement of the 

equipment shown, a mass and energy balance was developed within an ASPEN Plus4

 model. 

This model consists of 164 unit operation blocks, 457 streams (247 material and 210 heat or 

work), 63 components, and 82 control blocks. The overall model is thermodynamically rigorous 

and uses physical properties that are included in the ASPEN modeling software as well as 

property data developed at NREL5

. The individual unit models are thermodynamically consistent 

and can be either rigorous (for example, the simulation of the distillation) or simple. The reactors 

could be modeled with kinetic expressions, but because of the level of development of the 

3 
experimental data, they were modeled as experimentally determined conversions of specific 

reactions. The chemical formulas for atypical compounds (not included in the ASPEN modeling 

software) are listed in Appendix H. This type of model still satisfies the rigorous mass and 

energy balance. Other unit operations, such as liquid-solid separations, are typically modeled 

with fixed solids removal and liquid retention (in the solids stream) data from vendor tests. 

Using the PFDs and the mass and energy balance information from the ASPEN model, we 

developed specifications for each piece of equipment. The equipment specifications (and cost 

estimate) are detailed in the NREL process database (see Appendix A). Finally, within each 

equipment specification, we developed individual purchased equipment and installation costs. 

Equipment costs were obtained from vendor quotations when possible, especially for uncommon 

equipment such as pretreatment reactors. These costs reflect the base case for which the 

equipment was designed. If process changes are made and the equipment size changes, the 

equipment is not generally re-costed in detail. Using the following exponential scaling 

expression, the cost was determined by scaling based on the new size or other valid size related 

characteristic. 

 New Size * 

exp 

New Cost = Original Cost 



 Original Size * 





* or characteristic linearly related to the size 

If the size of the equipment is known to change linearly with the inlet flow, that information can 

be used for scaling. Another characteristic of the size might be the heat duty for a heat exchanger 

if the log-mean temperature difference is known not to change. Generally these related 

characteristics are easier to calculate and give the same result as resizing the equipment each 

time. For some equipment, nothing can be easily related to the size, so it must be resized with 

each process change. Heat exchangers with varying temperature profiles are one example. In 

this case, the heat exchanger area is calculated each time the model is run and the cost is scaled 

using the ratio of the new and original areas. 

The scaling exponent (exp) was obtained from vendor quotes (if two quotes at different sizes 

were obtained), Harris, or from a standard reference, such as Garrett.6 The installation costs were 

primarily taken from Delta-T’s experience and are explained in more detail in the process 

economics section (Section III). 

Once the scaled, installed equipment costs were determined, we applied overhead and 

contingency factors to determine a total plant investment cost. That cost, along with the plant 

operating expenses (generally developed from the ASPEN model) was used in a discounted cash 

flow analysis to determine the cost of ethanol production, using a set discount rate. For the 

analysis done here, the ethanol production cost is the primary value used to compare designs. 

Development of alternative designs is very useful in evaluating research proposals. Scenarios, 

based on technologies that might be developed after several years of research, are translated to 

process designs and the cost of ethanol production is evaluated. These projections are only as 

good as the estimation of the future technology developments. 

Even though one aim of this work was to develop the absolute cost of ethanol for comparison to 

other fuels, it should be noted that ethanol and possibly electricity are the only products of these 

conceptual process designs. It is likely that smaller volume, niche products will emerge, such as 

products from the biomass-derived sugars that will have a significantly higher profit margin than 

4 
fuel-grade ethanol. When these other products and their selling prices are figured into the 

analysis, the cost of ethanol may decrease, just as the cost of gasoline is reduced by the sale of 

other petroleum refinery products. Likewise, co-location with existing producers of ethanol, 

power, or some other equally synergistic product slate will likely reduce the cost of ethanol. 

I.2 Process Overview 

The process being analyzed here can be described as using co-current dilute acid prehydrolysis of 

the lignocellulosic biomass with enzymatic saccharification of the remaining cellulose and cofermentation of the resulting glucose and xylose to ethanol. The process design also includes 

feedstock handling and storage, product purification, wastewater treatment, lignin combustion, 

product storage, and all other required utilities. In all, the process is divided into eight areas (see 

Figure 2). 

The feedstock, in this case corn stover (comprised of stalks, leaves, cobs, and husks), is delivered 

to the feed handling area (A100) for storage and size reduction. From there the biomass is 

conveyed to pretreatment and detoxification (A200). In this area, the biomass is treated with 

dilute sulfuric acid catalyst at a high temperature for a short time, liberating the hemicellulose 

sugars and other compounds. Separation with washing removes the acid from the solids for 

neutralization. Overliming is required to remove compounds liberated in the pretreatment that are 

toxic to the fermenting organism. Detoxification is applied only to the liquid portion of the 

hydrolysis stream. 

Enzymatic hydrolysis (or saccharification) coupled with co-fermentation (A300) of the detoxified 

hydrolyzate slurry is carried out in continuous hydrolysis tanks and anaerobic fermentation tanks 

in series. A purchased cellulase enzyme preparation is added to the hydrolyzate in the hydrolysis 

tanks that are maintained at a temperature to optimize the enzyme’s activity. The fermenting 

organism Zymomonas mobilis is first grown in a series of progressively larger batch anaerobic 

fermentations to make enough cells to inoculate the main fermenters. The inoculum, along with 

other nutrients, is added to the first ethanol fermenter along with the partially saccharified slurry 

at a reduced temperature. The cellulose will continue to be hydrolyzed, although at a slower rate, 

at the lower temperature. After several days of separate and combined saccharification and cofermentation, most of the cellulose and xylose will have been converted to ethanol. The resulting 

beer is sent to product recovery. 

Product recovery (A500) involves distilling the beer to separate the ethanol from the water and 

residual solids. A mixture of nearly azeotropic water and ethanol is purified to pure ethanol using 

vapor-phase molecular sieve. Solids from the distillation bottoms are separated and sent to the 

boiler. Concentration of the distillation bottoms liquid is performed by evaporation, using waste 

heat. The evaporated condensate is returned to the process and the concentrated syrup is sent to 

the combustor. 

Part of the evaporator condensate, along with other wastewater, is treated by anaerobic and 

aerobic digestion (A600). The biogas (high in methane) from anaerobic digestion is sent to the 

combustor for energy recovery. The treated water is suitable for recycling and is returned to the 

process. 

The solids from distillation, the concentrated syrup from the evaporator, and biogas from 

anaerobic digestion are combusted in a fluidized bed combustor (A800) to produce high-pressure 

steam for electricity production and process heat. The majority of the process steam demand is in 

the pretreatment reactor and distillation areas. Generally, the process produces excess steam that 

is converted to electricity for use in the plant and for sale to the grid. 

5 
Figure 2. Overall Process, PFD-P110-A000 

6 
I.3 Plant Size 

In establishing the appropriate size of a plant, we must consider the effects of a number of 

tradeoffs. Savings resulting from economies of scale (see discussion in section I.1) are offset by 

increased costs for feedstock transportation. Put quite simply, the more feedstock a plant 

demands, the farther out it must go to get it. Collection distance for a plant is highly site specific, 

but a simple analysis can be done to understand the range of plant sizes for which overall costs 

and the impact of feedstock transport are minimal. This requires understanding both the cost of 

feedstock transportation and the effect of plant size on capital and fixed operating costs for the 

ethanol plant. 

On average, in the process industries, capital cost for equipment increases as a function of size or 

throughput according to the power law equation shown in section I.1 with an exponent of around 

0.6. This means that, per unit of output, the cost of capital can drop dramatically for larger scale 

operations. An exponent of 1 would mean linear scaling is taking place. An exponent less than 1 

means that the capital cost per unit size decreases as the equipment becomes larger. This concept 

is sometimes termed “economies of scale”. Economies of scale diminish when the equipment is 

as large as possible and multiple pieces of equipment become necessary. 

In 1991, NREL first evaluated the size of an ethanol plant for our standard design by looking at 

the trade off between economies of scale and increased cost of delivering feedstock.7 That study 

compared a plant size of around 1,750 metric tons (1 MT is 1,000 kg) or 1,920 short tons (1 ST is 

2000 lb) per day to one of 9,090 MT (10,000 ST), assuming an additional $2/ton transport costs 

for the larger plant size. In this report, we have repeated that analysis in a more rigorous way to 

see if a plant size of 2,000 MT per day is appropriate in the current design for converting corn 

stover to ethanol. 

I.3.1 Effect of Plant Size on Collection Distance 

NREL and ORNL recently completed a life cycle analysis of corn stover-derived ethanol.8 As 

part of that study, researchers at ORNL used a GIS model known as ORIBUS to estimate energy 

demands, environmental flows and costs for collection and transportation of corn stover in the 

state of Iowa (Figure 3). The premise of this study was that the maximum amount of stover that 

could be collected should be constrained by soil erosion considerations. An analysis of the 

effects of stover removal on soil erosion found that, for Iowa farmers using low or no till 

practices and who are producing corn continuously on their land, an average of two metric tons 

(MT) per acre of stover can be removed without causing erosion rates to exceed USDA’s 

tolerable soil loss limits. ORIBUS was used to estimate transportation costs for a total of 35 

potential ethanol plants sized to handle 2,000 MT (2,205 ST) per day of corn stover. 

Though the life cycle study of corn stover-derived ethanol in Iowa did not look at the effect of 

locating plants of different sizes, we can use the results of this study to calibrate a much simpler 

analysis of stover transportation costs in order to understand the trade-offs of transportation costs 

and savings due to economies of scale. 

7 
Figure 3. GIS Model results showing the location of 35 2000 MT/d ethanol plants in Iowa 

For this analysis, we need to estimate the distance traveled to collect corn stover, which, 

obviously, increases as the size of the plant increases. We estimate the collection distance as the 

radius of a circle around the plant within which the stover is purchased. The area of this circle is 

a function of the residue that can be collected per acre, the fraction of surrounding farmland from 

which stover can be collected and the fraction of farmland dedicated to crops (versus 

infrastructure): 

Areacollection = (Dstover/(Ystover*Favailableacres*Flandincrops) 

Where: 

Areacollection is the circle of collection around the plant 

Dstover is the annual demand for stover by an ethanol plant 

Ystover is MT stover collected per acre per year 

Favailableacres is the fraction of total farmland from which stover can be collected 

Flandincrops is the fraction of surrounding farmland containing crops 

The last two items warrant further explanation. In this simplified analysis we presume that the 

plant is located in the middle of corn farmland. Even so, not all of the land on a farm is available 

for planting crops. We assume that 25% of the land is tied up in infrastructure (e.g., roads and 

buildings), leaving 75% of the farm acres actually planted in corn. Thus, Flandincrops is taken to be 

0.75. Furthermore, we do not assume that all of the farms around the ethanol plant will want or 

be able to participate in the collection and sale of their corn stover. Thus, Favailableacres is a 

parameter we vary in the analysis. 

8 
Figure 4 shows the radius of collection around the plant for different levels of access to acres for 

collection, assuming a maximum yield of 2 MT per acre (as found in the Iowa life cycle study). 

100% access represents a scenario in which all farmers are practicing no till, growing corn 

continuously, and are willing to sell their stover. This is a highly unlikely scenario. 50% access 

represents a scenario in which farmers split their land between soybean and corn production. This 

scenario is also not very realistic because the corn-soybean rotations will not likely permit 

sustainable collection at a level of 2 MT (2.2 ST) per acre. 

120 

100 

80 

60 

40 

20 

-

0 2000 4000 6000 8000 10000 12000 

10% of available acres 

100% of available acres 

50% of available acres 

Plant Size (MT stover per day) 

Figure 4. The Effect of Plant Size on Collection Distance 

In the near term, the 10% availability scenario is closer to reality. Low till and no till practices do 

not represent a very substantial percentage of tilling practices for corn production in Iowa, or any 

where in the U.S.; and farmers using more intensive tilling practices will not be able to 

sustainably remove stover from their fields. In the future, it is very possible that farmers could be 

convinced of the financial, environmental and agronomic benefits of new tilling practices that 

lead to stover collection, but this is not a near term scenario. 

As a rough rule of thumb, we have assumed that plants would likely not collect corn stover 

outside of a 50-mile radius around the plant. For the 10% availability scenario, this 50-mile 

radius corresponds to the 2,000 MT per day design we have been using for our process design. 

Rather than using a rule of thumb to determine the limits of plant size and collection radius, it 

makes more sense to base the plant size on the cost of collection, which we address in the 

following sections. Radius of C

ollection (Miles) 

9 
I.3.2 Estimating Corn Stover Costs Today 

Collecting biomass for the plant has two main sources of direct costs: 

• The cost of baling and staging stover at the edge of the field 

• The cost of transportation from the farm to the plant gate 

In the past two years, Oak Ridge National Lab has been quantifying the cost of collecting corn 

stover assuming the use of existing equipment; and, more importantly, assuming that stover 

would be collected in a second pass through the field after the grain has been harvested. We 

know that such an approach will not suffice as the industry develops, but it does reflect the costs 

that we can anticipate for farmers collecting stover today. Furthermore, we have documented 

experience with such collection schemes.9 

Figure 5 shows the relative contribution of the sources of costs for stover collection and delivery, 

based on an analysis done by ORNL for our corn stover life cycle analysis: 

Total Delivered Stover Cost = $62 per dry MT ($56 per dry ST) 

Trans 18% 

K fertilizer 

23% 

P fertilizer 

port Farmer Premium 

4% 

N fertilizer 

6% 

2% 

Bale and Stage 

47% 

Figure 5. Typical Breakdown of Corn Stover Costs 

These costs represent a specific set of conditions that correspond to the scenario of 100% 

availability of acres, maximum levels of stover removal, with all costs averaged across a total of 

35 Iowa facilities processing 2,000 MT per day, as shown in Figure 3. Baling and staging, at $29 

per dry MT ($26 per dry ST), represents almost half the cost of delivered feedstock. The analysis 

includes the payment of a premium to farmers of $11 per dry MT ($10 per dry ST). This 

payment is above and beyond the cost of stover collection. For a yield of 2 MT per acre (2.2 ST 

per acre), this corresponds to a profit of $22 per acre. Informal discussions with the farm 

community suggest that $20 per acre is the likely threshold above which farmers would accept 

the risk and added work of collecting and selling their residue. Note that we have also included 

costs for added fertilizer requirements associated with the loss of nitrogen, potassium and 

phosphorous contained in the removed stover. Added fertilizer costs amount to around $8 per dry 

MT ($7 per dry ST). Transportation cost in this scenario is $14 per dry MT ($13 per dry ST). 

The average costs for transportation and baling costs are somewhat inflated in this analysis 

because they include costs for the last plants able to collect stover in Iowa. In the GIS analysis 

done for the life cycle study, individual 2,000 MT per day plants were located in sequence, with 

each new plant located to collect the lowest cost stover supplies. The last few plants have to go 

10 
much farther to obtain stover, and they must collect stover from the least cost effective sources of 

residue. 

It is important to note that the feedstock costs shown in this section are not the same as the 

nominal cost used in the process design economic analysis presented at the end of this report. 

This design is built on a series of assumptions tied to the successful achievement of research and 

development goals for the conversion technology. We have not yet developed cost-based targets 

for reducing the cost of feedstock collection and transport. As a placeholder in the process 

economics presented here, we have assumed that the nominal cost of corn stover will be reduced 

to around $33 per dry MT ($30 per dry ST) through improved collection (e.g. single pass) 

techniques. 

One final note about the cost of feedstock—the costs shown here are significantly higher than 

cost previously reported in the literature. That is because these costs include a premium paid to 

the farmer on top of the cost of collection and increased fertilizer application rates. Some 

estimates include no net payment to the farmer; while others include premiums, but assume that 

the cost of added fertilizer cost is hidden in the premium payment. One reason why these added 

costs for fertilizer and farmer premium have not been addressed is that there is tremendous 

uncertainty in these estimates. Nitrogen fertilizer cost, in particular, is hard to get a handle on. 

The composition data used to estimate fertilizer loss is sparse. The cost of stover collection 

presented here serve as a reasonable basis for testing the sensitivity of ethanol cost to plant size, 

but should not be regarded as an accurate assessment of corn stover collection costs. 

I.3.3 Effect of Distance on Stover Cost 

The only “real life” experience with transporting corn stover that has been documented in the 

published literature comes from the efforts by Biomass Agricultural Products (BMAP, LLC) in 

Harlan Iowa.

9 

11 
$18.00 

$16.00 

$14.00 

$12.00 

$10.00 

$8.00 

$6.00 

$4.00 

$2.00 

$-

0 to 15 16-30 31-50 50-100 

$6.71 

$9.65 

$12.58 

$15.51 

Radius from Plant (mi) 

Figure 6. Hauling Charges for Corn Stover as a Function of Distance 

In their collection study, BMAP established a pricing structure for corn stover that included 

hauler costs as a function of radial distance from the plant. Those costs are shown in Figure 6. In 

our evaluation of the trade-off of the costs of collection and the effect of plant size, we use the 

cost breakdown for stover shown in Figure 5, excluding the transportation cost. The linear 

relationship between cost and distance reported by BMAP is then substituted to predict a total 

cost of delivered corn stover that is a function of distance from the plant. 

I.3.4 Cost of Ethanol as Function of Plant Size 

The last piece of information required to conduct the analysis for choosing plant size requires 

estimates of the annualized cost and non-feedstock related operating costs of the plant. We use 

the costs as reported in the section on process economics later in this report (which are based on a 

2,000 MT per day design). But, we need to be able to take into account the effect of plant size 

(economies of scale). To do this, we need to substitute the annualized costs calculated for the 

2,000 MT per day design with an equation that recalculates annualized cost as a function of size 

using the power law type of equation for scale factor discussed earlier. In this analysis we used a 

capital cost scaling exponent of 0.7, which was calculated by rigorously modeling 2 different 

plant sizes and determining the exponent from each plant’s capital cost and feed rate10. Hauler Cost ($/MT) 

12 
$1.80 

$1.60 

$1.40 

$1.20 

$1.00 

$0.80 

$0.60 

$0.40 

$0.20 

$0.00 

0 2000 4000 6000 8000 10000 12000 

Total Cost 

Feedstock Cost 

Non Feedstock Cost 

10% access to 

surrounding corn acres 

Plant Size (MT stover per day) 

Figure 7. Ethanol Cost as a Function of Plant Size for 10% Availability of Corn Acres 

Figure 7 shows the minimum selling price for ethanol as a function of plant size for the 

conservative, but more likely near term, scenario of collecting stover from only 10% of the corn 

acres around the conversion facility. The non-feedstock and feedstock-related cost components 

are plotted along with the total cost. This figure demonstrates the nature of the trade-off quite 

clearly. The non-feedstock cost curve reflects the conventional wisdom of economies of scale. 

An increase in plant size from 2,000 to 10,000 MT per day reduces non-feedstock costs by $0.19 

per gallon, savings that seem well worth capturing. But the increased cost of feedstock for the 

10,000 MT per day design eliminates $0.13 of these savings. In this scenario, the net savings of 

$0.06 is achieved at a plant size between 6,000 and 8,000 MT per day, with no additional cost 

savings realized above that size. Plant sizes below the 2,000 MT per day design show rapidly 

increasing costs, suggesting that the 2,000 MT per day plant, under the assumed conditions, is a 

good choice for the minimum plant size. Thus, for the conservative scenario of collecting stover 

from 10% of the corn acres around a conversion plant, the optimal minimum plant size is in the 

2,000 to 4,000 MT per day range. 

As more acres of corn become available for stover collection, it is possible to increase the range 

of optimal plant designs, as shown in Figure 8. When available acres are increased from 10 to 

25%, savings in cost due to increased plant size top out at $0.10 per gallon up to a plant size of 

10,000 MT per day. For the case of full access to stover on surrounding corn acres, increasing Min Ethanol S

elling Price ($/gal) 

13 
plant size from 2,000 to 10,000 MT per day can realize savings of $0.16 per gallon, however, the 

lion’s share of these savings are achieved by the time you reach a plant size of 8,000 MT per day. 

$1.80 

$1.70 

$1.60 

$1.50 

$1.40 

$1.30 

$1.20 

$1.10 

$1.00 

0 2000 4000 6000 8000 10000 12000 

10% 

25% 

50% 

100% 

Plant Size (MT stover per day) 

Figure 8. Ethanol Price as a Function of Plant Size and % of Available Acres 

Another important factor impacting the cost of delivering feedstock is the cost per ton-mile. This 

cost is affected by the bulk density of the stover bales, the maximum number of bales per load 

and the road infrastructure itself. Lower bulk density and lower load capacity will increase the 

number of trips needed to deliver stover. Road infrastructure can be very important, as it impacts 

the maximum speed for haulers. The largest cost for hauling is in labor, which increases 

inversely as speed limit drops. Figure 9 shows the effect of the cost per ton-mile in the case of 

10% access to surrounding corn acres. A 50% increase in hauling cost per ton-mile reduces the 

range of optimum plant sizes to 2,000 to 5,000 MT per day (versus 2,000 to 8,000 MT per day for 

the 1x cost per ton-mile). At twice the our estimated cost per ton-mile, the range of optimal plant 

sizes not only shrinks to a maximum of around 3,000 MT per day, but higher plant sizes actually 

see significant increases in the minimum ethanol selling price. Min Ethanol S

elling Price ($/gal) 

14 
$1.70 

Min Ethanol S

elling Price ($/gal) $1.60 

$1.50 

$1.40 

$1.30 

$1.20 

$1.80 

2.0x 

1.0x 

1.5x 

10% access to 

surrounding corn acres 

$1.10 

$1.00 

0 2000 4000 6000 8000 10000 12000 

Plant Size (MT stover per day) 

Figure 9. Ethanol Price as a Function of Plant Size and Hauling Cost ($/ton-mile) 

I.3.5 Selecting the Right Plant Size 

The analysis presented here illustrates the need to understand and improve the technology and 

logistics of corn stover collection. Still, even when we consider a wide range of possible 

collection scenarios, we see that the minimum plant size of 2,000 MT per day holds reasonably 

well. Changes in assumptions about collection, however, can significantly impact the range of 

plant sizes over which it may be possible to realize cost savings. But the maximum plant size is 

unlikely to be above 8,000 MT per day. A more likely range for designs is 2,000 to 4,000 MT per 

day. 

It bears repeating that the cost estimates for stover used in this plant size analysis do not 

correspond to the nominal feedstock costs assumed in the detailed process design and economics 

summarized in this report. For the purposes of the process design, we used a nominal cost of $33 

per MT ($30 per ST); meaning that we implicitly assume that research going on at Oak Ridge 

National Lab and at USDA will lead to considerable cost reductions. The estimate of stover cost 

shown in this section is higher than previously reported stover costs, developed by Oak Ridge 

National Lab. ORNL has reported costs of $38 to $55 per MT of stover.11 At a delivered cost of 

$55 per MT, ORNL reports that almost all of the potential stover supply becomes available. 

In addition, the perspective of our studies is that of “nth” plants using high-volume biomass 

sources. We assume that these plants are located in the best locations for access to these 

feedstocks. In the near term, many of the pioneer plants will rely on niche feedstocks, which are 

15 
often spread out over much larger distances. Such plants may indeed be much smaller in size 

than our base case design assumes. 

I.4 Feedstock and its Composition 

The feedstock chosen for the process design has a significant impact on the overall analysis. The 

type of feedstock used will have a large effect on the feedstock-handling portion of the process, 

and the composition will certainly have an impact on how much ethanol is produced. 

The feedstock used for this analysis was corn stover; Table 1 shows the composition used. This 

composition is an average of the analyses of nine samples from two multi-ton batches of corn 

stover NREL received from Biomass AgriProducts (B/MAP) for use in lab and pilot studies

12. A 

feedstock analysis was converted to components that are used in the ASPEN model and 

normalized to 100%. In general, the component analysis of carbohydrates was used directly; 

other soluble compounds were combined under “extractives”. The unknown soluble solids 

component was used to normalize the composition to 100%; its heat of formation is calculated to 

balance the reported heating value of the feedstock with the calculated component heating values. 

Table 1. Feedstock Composition12 

Component % Dry Basis

Glucan 37.4 

Xylan 21.1 

Lignin 18.0 

Ash 5.2 

Acetate* 2.9 

Protein 3.1 

Extractives 4.7 

Arabinan 2.9 

Galactan 2.0 

Mannan 1.6 

Unknown Soluble Solids** 1.1 

Moisture 15.0 

*Acetate represents the acetate groups present in 

the hemicellulose polymer. They are generally 

converted to acetic acid in the prehydrolysis 

reactor. 

**Unknown soluble solids are calculated by 

difference to close the mass balance. 

Corn stover can vary in its composition and moisture content due to corn variety, region, weather, 

soil type, and harvesting and storage practices. NREL is working to bracket this variability and 

understand its effect on the process. Recent preliminary studies on corn variety13 and stover 

storage effects14,15 provide a larger range of data; the major constituents’ ranges are shown in 

Table 2. 

16 
Component

Table 2. Measured Stover Composition Ranges 

B/MAP

batches

12

Variety Studies13 Storage Studies14, 15

Glucan 36.1-39.1 35.6-38.3 29-41 33.3 +/-2.8 

Xylan 19.3-23.3 19.8-23.0 16-27.5 19.5 +/-2.8 

Lignin 17.2-18.9 Not reported 14-30 21.1 +/-0.8 

The mass balance data on corn stover presented here is preliminary and provides an estimate of 

its performance. We expect that as more research data on stover becomes available we will be 

able to make the process model more robust, tailoring its unique conversion reactions in the 

process to account for stover compositional effects. 

17 
II. Process Design and Cost Estimating 

The following sections describe in detail the process design and cost estimation for a biomass-toethanol process based on core technology developed by NREL. Generally, the data used for 

design have been demonstrated in the laboratory or pilot plant. In some cases, we extrapolated 

current experimental results to take into account anticipated technology advances over the next 1 

or 2 years of continued research (these extrapolations are noted in the text). More details of the 

design and cost estimation can be found in the NREL process engineering equipment database, 

which contains all engineering calculations and results from any vendors or costing programs. 

The database is described and partially summarized in Appendix A. Individual equipment 

information (costs, number of units, sparing) is listed in Appendix B. Process Flow Diagrams 

(PFDs) are contained in Appendix F. 

The cost estimate is based on the assumption that this is the “nth” plant, meaning that several 

plants using this same technology will have already been built and are operating. This means that 

additional costs for risk financing, longer start-ups, and other costs associated with first-of-a-kind 

plants are not included. 

The on-line time is 96%, which allows for a little more than two weeks of downtime. This was 

considered reasonable for an “nth” operating plant. 

II.1 Feedstock Storage and Handling – Area 100 (PFD-P110-A101) 

II.1.1 Overview 

Corn stover bales are received by the plant on truck trailers. As the trucks are received, they are 

weighed and unloaded by forklifts. Some bales are sent to on-site storage while others are taken 

directly to the conveyors. From there, the bales are conveyed to an automatic unwrapping system 

that cuts away the plastic wrapping and/or net surrounding the bales. The unwrapped bales are 

conveyed to a wash table, which both breaks up bales and washes dirt and grit from the corn 

stover. The washed stover is then conveyed past a magnetic separator to remove tramp metal, 

after which it is introduced to primary and secondary shredders where the material is reduced in 

size. Finally, the washed and milled stover is conveyed to prehydrolysis. It is possible that 

washing and sizing requirements may be reduced as we learn how sensitive the process is to dirt 

and particle size for stover. 

Dirty wash water is recycled and cleaned utilizing a clarifier-thickener system. The wash water is 

pumped to the clarifier where clean water is drawn off and recycled back to the wash tables. The 

underflow from the clarifier is then dewatered in a belt press. Because most of the wash water is 

recycled through this system, the fresh water requirement is low. 

II.1.2 Design Basis 

The as-received corn stover feed requirement for the plant is 98,039 kg/hr (216,178 lb/hr, 2,352 

MT per day [2,594 ST per day]) feedstock at 15% moisture. The corn stover bales are wrapped 

with plastic net to ensure they don’t break apart when handled, and may also be wrapped in 

plastic film to protect the bale from weather. The bales are either square or round, and the 

conceptual design applies equally to either shape. Square bales are typically 4 ft x 4 ft x 8 ft and 

weigh between 545 and 681 kg (1,200 and 1,500 lb). Round bales are approximately 70 inches in 

diameter, 5 ft long, and weigh around 545 kg (1,200 lb). The bales are received at the plant from 

off-site storage on large truck trailers. 

18 
Since corn stover is only harvested for a short period each year, long-term storage is required to 

provide feed to the plant year-round. Long-term storage will likely consist of 400-500 acres of 

uncovered piled rows of bales at a location (or multiple locations) reasonably close to the ethanol 

plant. On-site short-term storage is provided equivalent to 72 hours of production at an outside 

storage area. Bales and surrounding access ways as well as the transport conveyors will be on a 

concrete slab. A concrete slab is used because of the volume of traffic required to deliver the 

large amount of corn stover required. A concrete slab will minimize the amount of standing 

water in the storage area, as well as reduce the stover’s exposure to dirt. The stored material 

provides a short-term supply for weekends, holidays, and when normal direct delivery of material 

into the process is interrupted. This stored material will be rotated continuously, with a first-in, 

first-out inventory management strategy. 

In the projected design, trucks are received twelve hours daily, six days a week. After the trucks 

are weighed on the scales (M101) the bales are off-loaded by propane-fueled forklifts (M-102) 

and are placed directly onto two lines of bale transport conveyors (C-101) or in the short-term 

storage area. Bales are also reclaimed from short-term storage by forklifts (M-103) and loaded 

onto the bale transport conveyors. Each truck trailer holds 17 round bales, or 9.2 MT (10 ST), 

which is significantly below the weight limit for road considerations. To satisfy plant and storage 

requirements, the plant must receive 24 trucks every hour, with seven bales being unloaded every 

minute. Eight forklifts were deemed necessary to satisfy this schedule; four to unload trucks and 

four to draw bales from short-term storage. Each forklift is capable of operating with a 33-lb 

propane tank for an 8-hour shift. Individual propane canisters are refilled at bulk storage on-site. 

When trucks are not being unloaded, all eight forklifts are used to move feed from short-term 

storage. 

The original stover handling design from Harris16 stated that each truck would hold 30 bales. 

However, the current stover harvesting operation in Harlan, Iowa, uses trailers that hold a 

maximum of 17 round bales

9

, and this is the number used by Oak Ridge National Laboratory in 

their feedstock logistics work. We feel that this information is the best currently available for 

baled stover transport. Thus, the Harris design was altered to accept 17 round bales per truck 

instead of the original 30 bales per truck. 

Bales travel to one of two bale unwrapping stations (C-102), which are sized to handle 90 bales 

each per hour. Unwrapped bales are transported to wash tables (M-104). The wash tables break 

the bales with a spreader bar and pull the stover up a 45° incline using metal teeth attached to a 

drag chain. Water is sprayed on the corn stover as it is conveyed up the incline. This washes dirt 

and grit from the product and allows water to drain from the stover. Washing the stover prior to 

cutting or shredding minimizes the amount of moisture that is absorbed by the product. 

The washed stover is then discharged onto a conveyor (C-104) and passes a magnetic separator 

(S-103) to remove tramp metal prior to shredding. The stover is introduced to a primary shredder 

and then a secondary shredder (M-105), which reduces the stover to the proper size for 

prehydrolysis. This size has not yet been optimized for prehydrolysis of corn stover; but the 

shredders were specified to produce material that is a maximum of 1.5 inches long. Each 

shredder is sized to process 25.2 MT (28 ST) of stover per hour. Without experience using this 

washing concept for corn stover, the estimated moisture content of the shredded stover is 30%-

40%. 

The wash table design was taken from the sugar cane processing industry where they wash the 

sugar cane prior to processing. A 24 ft wide cane table can typically handle up to 4,082 MT 

19 
(4,500 ST) per day of cane. Since stover is less dense than cane, 2,000 MT per day is a 

reasonable size for a 24 ft wide machine. Each table is capable of spraying approximately 568 

m3

/hr (2,500 gpm) of wash water; more water can be used by adding more or larger spray 

nozzles. The actual wash water requirement for stover has not been determined; 568 m3

/hr was 

used in the design. 

Dirty wash water is recycled through a clarifier-thickener (S-101, T-102) to remove solids with 

the help of a polymer. Underflow from the thickener is dewatered in a belt press (S-102). The 

dewatered underflow is primarily topsoil and corn stover fines. This is disposed of via land 

application to nearby fields. The amount of fresh water make-up will depend upon the belt-press 

efficiency and the absorption capacity of the stover. Because most of the water is recycled to a 

wash water tank (T-101) and back to the wash tables, fresh water consumption is approximately 

43,000 kg/hr, or 4% of the total wash water. Approximately 1% of the wash water is expected to 

evaporate from the open wash system (11,400 kg/hr). The other 3% of the wash water consumed 

is mostly absorbed by the stover; a small portion of the water leaves with the topsoil and stover 

fines. 

Most of the equipment specified has been used in commercial straw, corn stover, or sugar cane 

processing industries. The automatic unwrapping station is the only equipment that has not yet 

been commercially applied. Cross Wrap OY, Finland, has bale-wrapping systems for plastic film 

and has developed some de-baling technology, but this must be modified for stover bales 

wrapped with plastic net and film. Manual bale unwrapping is feasible but would be too labor 

intensive for an operation of this size. 

Due to the bale handling, eight forklift operators each shift are envisioned to unload trucks and 

maintain the feedstock supply to the process. 

II.1.3 Cost Estimation 

Harris obtained vendor cost estimates for the forklifts, wash tables, shredders, clarifier-thickener, 

and belt press. Cross Wrap, OY, estimated the bale unwrapping equipment cost for an “nth” 

plant. Harris estimated the other equipment costs (pumps, conveyors, tank, concrete) based on 

their experience. 

II.2 Pretreatment and Hydrolyzate Conditioning – Area 200 (PFD-P110-A201-3) 

II.2.1 Overview 

The pretreatment and hydrolyzate conditioning process area converts, by hydrolysis reactions, 

most of the hemicellulose portion of the feedstock to soluble sugars - primarily xylose, mannose, 

arabinose, and galactose. Glucan in the hemicellulose and a small portion of the cellulose are 

converted to glucose. This conversion is accomplished using dilute sulfuric acid and high 

temperature. These conditions also solubilize some of the lignin in the feedstock and “expose” 

the cellulose for subsequent enzymatic hydrolysis. In addition, acetic acid is liberated from the 

hemicellulose hydrolysis. Degradation products of pentose sugars (primarily furfural) and hexose 

sugars (primarily hydroxymethyl furfural (HMF)) are also formed. 

Following the pretreatment reactor, the hydrolyzate liquid and solids are flash cooled, which 

vaporizes a large amount of water, a portion of the acetic acid, and much of the furfural and HMF 

(see Figure 10). Removing these heterocyclic aldehydes is beneficial, as they can be toxic to 

downstream fermentation microorganisms. 

20 
Figure 10. Pretreatment Process Area Overview, PFD-P110-A200 

21 
In addition to flash removal of aldehydes, the solids are washed and pressed to separate the liquid 

portion of the hydrolyzate, containing sulfuric acid, from the solids. The liquid is then 

“overlimed,” or raised to pH 10 (by adding lime) and held for a period of time. Neutralization 

and precipitation of gypsum follow the overliming step. The gypsum is filtered out and the 

hydrolyzate is mixed with the solids (cellulose) and dilution water before being sent to 

saccharification and co-fermentation (Area 300). 

II.2.2 Design Basis 

The washed, shredded corn stover is fed to pretreatment and first steamed with low-pressure 

steam in a presteamer to about 100°C (see PFD-P110-A201). This steam removes noncondensables that can take up space in the reactor and allows about one-third of the total 

prehydrolysis reaction heat requirement to be satisfied by low-pressure steam. The presteamer17 

is fed by a set of screw conveyors with variable frequency drives to vary the feed rate as the 

process may dictate. The presteamer is a horizontal vessel with paddles on an interior center 

shaft to move the stover. The discharge from the presteamer is a variable-frequency screw 

conveyor leading to a blow tank. The blow tank is used as a seal between the presteamer and the 

reactor. The blow tank has a live bottom screw to feed the material to the reactor. Steam is 

injected into the screw to pressurize it on the way to the reactor. Anco-Eaglin, Inc. (AncoEaglin), the manufacturer, described the steam injection as a venturi-like arrangement. The steam 

acts as a motive force to pull the material into the reactor. A plug is formed in the screw, 

maintaining the pressure in the reactor. The reactor also has paddles on an interior center shaft to 

help move the material. The close-pitch flights in the discharge screw compact the material so 

that it acts as a seal coming out of the vessel. 

The presteamer was designed for a maximum 20-minute residence time, which is used in pulping. 

The time could be shorter, depending on the particle size. The horizontal reactor vessel is 

designed to be 95% full with 10 minutes of residence time. Anco-Eaglin’s experience is that 

proper mixing and cooking can be achieved with this fill percentage. Because of the large vessel 

fill percentage, fewer vessels are required. The original Anco-Eaglin quote was for a 10-minute 

residence time; the reactor cost was adjusted for the shorter target residence time of 2 minutes. 

Three reactor trains (each including a presteamer, blow tank, reactor) are used. NREL and other 

pretreatment research groups are studying the operability of a continuous reactor at short 

residence times. 

After the stover is steamed, acid is added to the reactor. Concentrated sulfuric acid is diluted with 

evaporator condensate (see Section II.5) until the mixture (the total water, including steam and 

acid) in the reactor is 1.1% sulfuric acid. The total stover mixture now constitutes 30% insoluble 

solids. The reactor is brought up to temperature by direct injection of 13 atm (191 psia) (192°C 

saturation temperature and 76°C superheat) turbine extraction steam. The pretreatment reactor 

(M-202) operates at 12.1 atm (177 psia) pressure and 190°C. Heat losses from the reactor were 

not accounted for in the energy balance calculations. Table 3 summarizes the conditions in the 

pretreatment reactor. 

Table 3. Pretreatment Hydrolyzer Conditions 

Acid Concentration 1.1% 

Residence Time 2 minutes 

Temperature 190°C 

Pressure 12.1 atm (177 psia) 

Solids in the Reactor 30% 

22 
Table 4 summarizes the resulting reactions and the conversions that take place in the pretreatment 

hydrolyzer. The conversion value is the fraction of reactant converted to product. The other 

hemicellulose carbohydrates (arabinan, mannan, galactan) are assumed to have the same reactions 

and conversions as xylan. 

Table 4. Pretreatment Hydrolyzer Reactions and Conversions 

Reaction Reactant Fraction

Converted 

to Product 

(Glucan)n + n H2O → n Glucose Glucan 0.07 

(Glucan)n + m H2O → m Glucose Oligomer Glucan 0.007 

(Glucan)n + 1⁄2n H2O → 1⁄2n Cellobiose Glucan 0.007 

(Xylan)n + n H2O → n Xylose Xylan 0.90 

(Xylan)n + m H2O → m Xylose Oligomer Xylan 0.025 

(Xylan)n + → n Furfural + 2n H2O Xylan 0.05 

Acetate → Acetic Acid Acetate 1.0 

(Lignin)n → n Soluble Lignin Lignin 0.05 

Glucose and xylose oligomers are sugars bound in soluble oligomer form. 

The exiting material from the pretreatment reactor is flash cooled to 1 atm (14.7 psia) in T-203. 

The flash vapor is modeled with the Hayden and O’Connell

18 equation of state to specifically 

model the vaporization of acetic acid. Acetic acid creates dimers in the vapor phase and this 

equation of state properly accounts for them. If the vapor phase dimerization of acetic acid is not 

accounted for, the loss of acetic acid in the vapor will be over estimated. In this flash, 7.8% of 

the acetic acid and 61% of the furfural and HMF are removed. 

The flash vapor, about 53,000 kg/hr (117,000 lb/hr) of essentially 100°C steam, is used to preheat 

the beer column feed in H-201. During this exchange, the beer column feed is heated to 95°C 

and the entire flash vapor from T-203 is condensed. The condensed flash vapor is sent to 

wastewater treatment (Area 600). 

After a residence time of 15 minutes in the flash tank, the hydrolyzate slurry with 21% insoluble 

solids is conveyed to a Pneumapress pressure filter (S-205) to separate the solids and the liquids 

(see PFD-P110-202). The liquids are separated from the solids to facilitate conditioning of the 

liquid portion to reduce toxicity of the stream to downstream fermentation. 

Harris considered different types of solid-liquid separation equipment19; two makes of decanter 

centrifuges and several types of filters (filter press, belt filter press, pressure filter). The 

Pneumapress, a pressure belt filter press, provided the best recovery of solids, and solubles with 

minimal wash water. 

The Pneumapress pressure filter provides automated batch liquid-solid separation by forcing 

compressed air (125 psig) through the biomass slurry and filter media to displace liquid, 

maximizing the solid content of the cake on the filter. Very high cake solids levels and cake 

washing efficiencies are advantages to using this equipment. Bench scale testing19 has shown that 

dry cakes, near 55% insoluble solids with 99.5% insoluble solids recovery, are possible with this 

unit. Those tests also showed that 95%-96% cake washing efficiencies are possible in two wash 

cycles with a wash water to feed mass ratio of 0.58. The cycle times of this batch unit are 

23 
typically quite short (<10 minutes). The Pneumapress filter was also cost competitive with the 

other types of separation equipment. 

The cyclic operation of the Pneumapress pressure filter system is as follows. Pretreated slurry is 

pumped from the blowdown tank into the hydrolyzate mixing tank (T-205) and mixed with 

recycled filtrate liquor (from tank T-213) to reduce the insoluble solids in the slurry to a 

pumpable level, having a suspended solids concentration that is capable of being fed to the 

Pneumapress, approximately 10%. That diluted slurry is pumped into the Pneumapress, building 

pressure in the Pneumapress and pushing filtrate through the filter. The filtrate flows to the wash 

filtrate tank (T-213). The cake is then washed with liquor that is pumped from the primary 

filtrate tank (T-211). Filtrate from that cycle also flows into the wash filtrate tank (T-213). 

Finally, the cake is washed with recycle water (stream 252) and air is blown through it to displace 

the liquor, which is primarily water. Filtrate from the final washing flows into the primary filtrate 

tank (T-211). The air is sent through a condenser to remove water and other condensables and 

then to the combustor as combustion air. Volatile organic compounds (VOC) in the air are 

combusted. Condensate is sent to wastewater treatment. 

The final cake is conveyed off of the Pneumapress onto a transport conveyor and into the 

slurrying tank (T-232) where it is mixed with conditioned hydrolyzate liquor and additional 

recycle water. Product liquor to be conditioned is pumped from both the primary filtrate tank and 

the wash filtrate tank to a heat exchanger (H-200) where it is cooled to 50°C using cooling water. 

The temperature of 50°C was chosen because the next unit operation, overliming, is run at that 

temperature. Liquor from the wash filtrate tank is also used to dilute the pretreated slurry. 

The plant air compressor provides air at 9.5 atm (140 psia) to the Pneumapress filters. 

After the separation step the material is overlimed (see PFD-P110-A203). Lime is added in tank 

T-209 to raise the pH to 10. The residence time in T-209 is one hour to allow for the overliming 

“reactions” to occur.

20 Based on the experience of Delta-T, the agitation for this application is 

assumed to be 98.5 W/m3

 (0.5 hp/1000 gal). The liquid is then adjusted to the fermentation pH of 

4.5 in tank T-224 and held for four hours. This long residence time allows the resulting gypsum 

crystals to form to a size that can be readily separated by hydrocyclone and rotary drum filtration 

in series.21 Agitation power for T-224 was set at 98.5 W/m3

 (0.5 hp/1000 gal), again based on 

Delta-T’s experience. The filtration is assumed to remove 99.5% of the precipitated gypsum and 

the solids are assumed to contain 20% liquid.22 At 80% solids, gypsum can be handled as a dry 

solid. This approach was recommended by vendors and is typical of dewatering equipment used 

in the utility flue gas desulfurization industry to achieve high gypsum solids concentrations 

commercially. 

After the gypsum is filtered, the conditioned hydrolyzate liquid is recombined with hydrolyzate 

solids (which were separated in S-205) in Tank T-232 (see PFD-P110-A202). The residence time 

in this tank is minimal (15 minutes) just long enough to afford good mixing. The agitation for this 

application is assumed to be 394 W/m3

 (2 hp/1000 gal) based on the experience of Delta-T. The 

resulting slurry, now conditioned, pH-adjusted, and properly diluted, is pumped to fermentation 

(Area 300). 

II.2.3 Cost Estimation 

All pumps, tanks, screw conveyors, and agitators for this section were estimated using the 

ICARUS Process Evaluator.

23 The material of construction for all equipment except the 

pretreatment reactor (M-202), flash tank (T-203) and Pneumapress equipment is 304SS, based on 

24 
the experience of Delta-T. The material of construction of the flash tank is SS316 because 

additional acid resistance at temperatures higher than 100°C is necessary. Harris recommended 

mostly SS316 for the solid-liquid separation equipment in contact with the process. 

Harris obtained quotes for the continuous pretreatment reactors from Anco-Eaglin, Inc. The 

construction materials were assumed to be Incoloy 825-clad steel for all parts in contact with 

acid, based on corrosion data generated by Intercorr of Houston via Harris17. This includes vessel 

paddles and shafts. Stainless steel (316L) was assumed for most other reactor parts including the 

presteamer. Anco-Eaglin felt the cost estimate provided reflected an nth plant cost because it was 

based on similarly designed equipment currently in service. 

NREL engineers have developed a spreadsheet-based model to predict general corrosion rates in 

acid and temperature environments for various alloys, based on sets of corrosion data from 

various corrosion studies performed in the last several years.24 While not rigorous, it can provide 

guidance when considering metallurgy for varying conditions. For solid Incoloy 825, the 

corrosion rate at the target pretreatment conditions is expected to be less than 20 mils per year (a 

mil is a thousandth of an inch), which is considered satisfactory resistance. Figure 11 shows the 

effect of temperature and acid concentration on corrosion rate for Incoloy 825. As either 

parameter increases, the corrosion resistance is reduced. 

100 

1.5 wt% Sulfuric Acid 

0.5 wt% Sulfuric Acid 

Good Corrosion 

Resistance 

Satisfactory 

Corrosion 

Resistance 

Unsatisfactory Corrosion Resistance 

10 

Corrosion Rate (mpy) 

1 

0.1 

0.01 

0 50 100 150 200 

Temperature (°C) 

Figure 11. Corrosion Resistance of Incoloy 825 

The cost estimate for the liquid solid separators S-205 and S-222 are based on vendor quotations 

from Pneumapress and Komline Sanderson respectively. Three Pneumapress units are required 

to accommodate the process flowrate. 

25 

250 
II.2.4 Achieving the Design Case 

Table 5 lists conditions that have produced good yields from NREL’s 1 ton per day, continuous 

Sunds vertical reactor and conditions that produced higher yields from the 4L steam gun. 

Table 5. Experimental Pretreatment Hydrolyzer Conditions 

Sunds Reactor25 Steam Gun26

Acid Concentration 1.16% 1.1% 

Residence Time 6.2 minutes 2 minutes 

125 

Temperature 

179°C 190°C 

Pressure 9.7 atm (142 psia) 12.1 atm (177 psia) 

Solids in the Reactor 19% 37 – 47% 

Table 6 summarizes the resulting reactions and the conversions for the experimental runs in each 

reactor. The measured values were taken from experiments conducted at the conditions in Table 

5. For the Sunds run, the total carbon recovery was approximately 105%, so about 5% more 

carbon was measured in the product streams than in the feed stream. This carbon recovery is 

slightly higher than previous experiments but is within a standard range of carbon mass balance 

closure of 90 to 105%. High or low carbon closure is typically caused by imprecision in the 

experimental and analytical methods, or the creation of degradation products that are not 

identified in the analysis. 

Table 6. Experimental Pretreatment Hydrolyzer Reactions and Conversions 

Reaction Reactant Fraction Converted to Product

Sunds 

Reactor25

Steam

Gun26

Design 

Case

(Glucan)n + n H2O → n Glucose Glucan 0.0675 0.081 0.07 

(Glucan)n + m H2O → m Glucose 

Oligomer 

Glucan 0.006 0.0 0.007 

(Glucan)n + 1⁄2n 

H2O 

→ 1⁄2n Cellobiose Glucan 0.008 0.0 0.007 

(Xylan)n + n H2O → n Xylose Xylan 0.675 0.837 0.90 

(Xylan)n + m H2O → m Xylose Oligomer Xylan 0.029 0.126 0.025 

(Xylan)n + → n Furfural + 2n 

H2O 

Xylan 0.159 0.03 0.05 

Acetate → Acetic Acid Acetate 1.0 0.638 1.0 

(Lignin)n → n Soluble Lignin Lignin Not 

Reported 

Not 

Reported 

0.05 

Glucose and xylose oligomers are sugars bound in soluble oligomer form. 

The design case conditions and conversions for the reactor are based on the experimental runs in 

the Sunds and the 4L steam gun. Lignin solubilization and solids loading values are based on 

recent runs in the Sunds pilot reactor27. Conversion of the minor hemicellulose carbohydrates 

(arabinan, mannan and galactan) was assumed the same as xylan for the design case. Scale-up of 

these conditions to a continuous horizontal reactor is underway in addition to running these 

conditions in the vertical one dry ton per day Sunds reactor. The xylose oligomers may be 

reduced via optimization of the pretreatment conditions, a hold tank, or hemicellulase activity in 

the enzyme preparation. The Anco-Eaglin reactor is a horizontal configuration with a throughput 

26 
of about 700 dry MT per day for one unit. Understanding how the reaction kinetics change with 

different reactors sizes and with configuration is important to know when the pretreatment has 

been scaled up adequately that accurate prediction is possible at larger scales. Data from these 

three reactors will be used to understand and predict conversion rates as a function of size and 

configuration in addition to process parameters like temperature. While Anco has not previously 

worked with corn stover, they are pursuing opportunities to do so. 

The mechanism of detoxification by overliming is not completely understood. Overliming is a 

temperature and pH treatment designed to aid the conversion of hydrolyzate sugars to ethanol 

during fermentation28. The procedure varies in the literature but always includes an adjustment of 

pH, a temperature increase, a hold at temperature for 15 to 30 minutes, and a hot filtration. 

Overliming was originally designed to limit the calcium concentration in solution to organismtolerant levels. In many organisms calcium is involved in membrane transport, so minimum 

concentrations may be necessary for efficient sugar uptake. 

Research is currently under way to determine if the overliming process is removing, adding, or 

changing the form of a component, or a combination of all of these.29 We now know that 

controlling calcium concentrations is not the only advantage of overliming. Overliming also 

appears to catalyze condensation reactions in lignin-derived compounds. These reactions 

detoxify the hydrolyzate and the detoxification is more efficient at higher pH. Investigations into 

the specific functional groups involved in this detoxification are being performed under a NREL 

subcontract. We hope to use knowledge of the actual chemical reactions involved in lignin 

detoxification to guide selection of alternatives to overliming that do not require lime addition 

and gypsum removal. Enzyme systems that condense lignin or processes that remove very low 

molecular weight lignin are possible alternatives. 

One of the biggest challenges in overliming at an industrial scale will be accurate pH control. By 

pH 11, as much as 30% of the glucose may be lost to HMF and other side reactions. Several 

factors increase the probability of overshooting pH endpoints during overliming. The natural 

buffering capacity of hydrolyzates causes neutralization reactions to be slow. Measurements 

using pH membrane probes are affected by temperature and the presence of dissolved organic 

compounds (sugars and lignin). 

II.3 Saccharification and Co-Fermentation–Area 300 (PFD-P110-A301-2) 

II.3.1 Overview 

Two different operations are performed in this process area—saccharification of the cellulose to 

glucose using cellulase enzymes, and fermentation of the resulting glucose and other sugars (from 

the dilute acid pretreatment of hemicellulose, Area 200) to ethanol. 

Hydrolysis, or saccharification, occurs first, separately from the fermentation. The separate 

saccharification step enables operation of the saccharification step at an elevated temperature to 

take advantage of increased enzyme activity and reduce the time and amount of enzyme required. 

The enzyme used to saccharify the cellulose is purchased from an enzyme manufacturer. The 

cellulase enzyme and diluted, detoxified hydrolyzate are continuously added to a train of five 1-

million gallon vessels. 

Cellulase enzyme is actually a collection of enzymes. This collection is comprised of: (1) 

endoglucanases, which attack randomly along the cellulose fiber to reduce polymer size rapidly; 

(2) exoglucanases, which attack the ends of cellulose fibers, allowing it to hydrolyze highly 

27 
crystalline cellulose; and (3) β-glucosidase, which hydrolyzes cellobiose to glucose. Several 

bacteria and fungi naturally produce these enzymes, including bacteria in ruminant and termite 

guts and white rot fungus.30 The most common organism used to produce cellulase industrially is 

Trichoderma reesei. Genencor International and Novozymes Biotech, the two largest enzyme 

manufacturers in the world are developing more cost effective cellulase enzymes. DOE is 

funding this important work, which will improve the economic viability of biomass conversion. 

For fermentation, the recombinant Z. mobilis bacterium31 is used as the biocatalyst. This form of 

Z. mobilis will ferment glucose and xylose to ethanol. It is assumed that mannose and galactose 

sugars are also fermented in this design. Several research institutions32 are genetically 

engineering strains, such as Z. mobilis, to utilize additional sugars, or are identifying naturally 

occurring organisms that metabolize hemicellulosic sugars. 

The Z. mobilis must be “grown” in a seed fermentation train of vessels in this process area. 

Saccharified slurry and nutrients are combined with an initial seed inoculum (grown in the 

laboratory) in a very small vessel. The result of each seed batch is used as the inoculum for the 

next size seed increment. This series of scale-ups is continued until the last step is large enough 

to support the production fermentation. 

Finally, the seed inoculum, nutrients, and saccharified slurry are added to a train of continuous 

fermentors. It is really a simultaneous saccharification and co-fermentation (SSCF) configuration 

at this point, because although the temperature in the fermentation tanks will be lower by 

necessity because of the ethanologen’s thermal tolerance, the enzyme will still continue to 

hydrolyze cellulose. The number of fermentors will be about five 1-million gallon vessels in a 

train or line. The resulting ethanol broth is collected in a beer well (storage tank) before it is 

pumped to distillation. 

II.3.2 Design Basis 

Detoxified and diluted hydrolyzate fed to the saccharification vessels is about 20% total solids33 

(soluble and insoluble solids) including the dilution that will occur when the cellulase stream is 

mixed in. The enzyme loading is determined by the amount of cellulose present in the 

hydrolyzate and the target hydrolysis conversion level with the combined residence time of the 

saccharification tanks and the fermenters. A heat exchanger (H-301) heats the 51°C hydrolyzate 

slurry exiting the re-acidification tank (T-224) to 65°C, the saccharification temperature, using 

low-pressure steam. 

Saccharification takes place in five 950,000-gal vessels (see PFD-P110-A302). The total 

residence time is estimated at 36 hours. Because the cellulase enzyme is still being developed, 

the actual split of time between saccharification and fermentation (actually simultaneous 

saccharification and fermentation) is not known, but it is likely that some time in an SSF mode 

will be needed to reach 90% hydrolysis yields. The tanks are cooled using a pump-around loop 

that consists of a centrifugal pump (P-310) and heat exchanger (H-310). The heat exchanger is 

cooled with cooling water. For this design case, cellulase is fed at the rate of 12 international 

filter paper units (IFPU) per gram of cellulose assuming an enzyme concentration of 50 

FPU/mL34. Target conditions, developed with the enzyme manufacturers, take advantage of 

improved thermal tolerance to reduce the required time and loading; they are summarized in 

Table 7. 

28 
Table 7. Saccharification Conditions 

Temperature 65°C 

Initial Saccharification Solids Level 20% total solids 

Residence Time 1.5 days 

Size of Vessels 3,596 m3

 (950,000 gal) each 

Number of Vessels 5 

Number of Continuous Trains 1 

Cellulase Loading 12 FPU/g cellulose 

Table 8 lists the reactions and conversions taking place in saccharification. The saccharified 

slurry contains 12.6% sugars including 7% glucose and 4% xylose. All of the cellulose 

hydrolysis is modeled to take place in the saccharification vessels until there is a better 

understanding of how much hydrolysis will occur at the fermentation conditions. The stream 

contains about 1% acetic acid and less than 0.5% of furfural and HMF combined, all of which can 

inhibit ethanologens at higher concentrations. 

Table 8. Saccharification Reactions and Conversions 

Reaction Reactant Fraction

Converted 

to Product 

(Glucan)n → n Glucose Oligomer Glucan 0.04 

(Glucan)n + 1⁄2n H2O → 1⁄2n Cellobiose Glucan 0.012 

(Glucan)n + n H2O → n Glucose Glucan 0.90 

Cellobiose + H2O → 2 Glucose Cellobiose 1.0 

Saccharified slurry is cooled (H-302) to 41°C and a portion is sent to the seed production area. 

The total amount of saccharified slurry split off to seed production is 10%. The required 

inoculum volume has been experimentally determined to be 10%,

35 both for the seed train and the 

production train. The seed train is operated in a batch mode (see PFD-P110-A301). The batch 

time for each step is 24 hr.

36 Delta-T Corporation decided two trains would be optimal using an 

assumed turn-around time for each seed fermenter of 12 hr. Using these conditions, Train A will 

complete its fifth stage of fermentation at 180 hours. Train B will then complete its final stage of 

fermentation 12 hours later. 24 hours after that, Train A is again complete and the cycle 

continues. Based on the production flow of about 8,700 m3

/day (2.3 million gallons/day), the 

seed volume to be produced each day is 870 m3

 (230,000 gal), or 435 m3 (115,000 gal) every 12 

hr. Each batch must be 655 m3

 (173,000 gal) to satisfy the 12-hr period that is skipped. If three 

trains were used, the maximum volume would be only 435 m3

 (115,000 gal), but because there 

would be three trains it would be more costly. Considering a 90% working volume, the 

maximum size seed fermenter is 727 m3

 (192,000 gal). Scaling down by a factor of 10 for each 

smaller stage results in four additional seed fermenters of 72.7, 7.6, 0.8, and 0.08 m3

 (19,200, 

2000, 200, and 20 gallons). Table 9 summarizes the seed train design specifications. 

29 
Table 9. Seed Train Specifications33,35,36 

Inoculum Level 10% of total 

Batch Time 24 hr 

Fermenter Turn-Around Time 12 hr 

Number of Trains 2 

Number of Fermenter Stages 5 

Maximum Fermenter Volume (F-305) 727 m3

 (173,000 gal) 

Corn Steep Liquor (CSL) Level 0.5% 

Diammonium Phosphate (DAP) Level 0.67 g/L fermentation broth 

The two largest seed fermenters are large tanks (F-304 and F-305) with internal cooling coils (H304 and H-305) and agitators (A-304 and A-305) that are costed separately. The small fermenters 

are package units (agitator and jacket included). Well water at 13°C, supplemented with cooling 

water is used to maintain the fermenters at 41°C. The well water is then used as make-up water 

to the process. The coil size was calculated using a tank coil correlation from Kern37. The 

agitators were sized based on Delta-T’s experience with similar systems. The design numbers for 

agitation were 20 W/m3

 (0.1 hp/1000 gal) for the largest fermenter (F-305) and 60 W/m3 (0.3 

hp/1000 gal) for F-304. The three smaller seed fermenters (F-301-3) are designed as packagejacketed, agitated reactors. ICARUS23 was used to estimate the agitation powers of 0.75 kW (1 

hp) for F-301, 3.7 kW (5 hp) for F-302, and 18.6 kW (25 hp) for the F-303. 

Table 10 gives the reactions and conversions used in the seed fermentations to describe the 

microorganism growth and sugar metabolism. Full mass balances have not been attempted for 

conditions that favor cell growth as they would in the seed train38. 

30 
Table 10. Seed Train Reactions and Conversions 

Reaction Reactant Fraction

Converted 

to Product38

Glucose → 2 Ethanol + 2 CO2 Glucose 0.90 

Glucose + CSL + 

0.018 DAP 

→ 6 Z. mobilis + 2.4 H2O + 0.3 O2 Glucose 0.04 

Glucose + 2 H2O → 2 Glycerol + O2 Glucose 0.004 

Glucose + 2 CO2 → 2 Succinic Acid + O2 Glucose 0.006 

Glucose → 3 Acetic Acid Glucose 0.015 

Glucose → 2 Lactic Acid Glucose 0.002 

3 Xylose → 5 Ethanol + 5 CO2 Xylose 0.80 

Xylose + 0.835 CSL 

+ 0.015 

DAP 

→ 5 Z. mobilis + 2 H2O + 0.25 O2 Xylose 0.04 

3 Xylose + 5 H2O → 5 Glycerol + 2.5 O2 Xylose 0.003 

Xylose + H2O → Xylitol + 9.5 O2 Xylose 0.046 

3 Xylose + 5 CO2 → 5 Succinic Acid + 2.5 O2 Xylose 0.009 

2 Xylose → 5 Acetic Acid Xylose 0.014 

3 Xylose → 5 Lactic Acid Xylose 0.002 

Corn steep liquor (CSL) and Diammonium Phosphate (DAP) are both nitrogen sources required for Z. mobilis 

growth. The usage rates for these nutrients are the same as used in laboratory fermentations; however the 

stoichiometry used to model the reactions has not been experimentally verified. 

Two high-capacity transfer pumps are used (P-302) to transfer the seed to the seed hold tank (T301) in a timely fashion (approximately 2.5 hr). Two pumps are required because this is the 

largest rotary lobe pump available from Waukesha Pump Company. A rotary lobe pump is used 

to avoid damaging the microorganisms by pump sheer. 

The seed hold tank (T-301) is sized to hold 20% more than the fifth seed reactor (F-305). A 

rotary lobe pump (P-301) is then used to continuously feed the seed to the production 

fermentation train. 

Co-fermentation is conducted in 950,000-gal vessels (see PFD-P110-A302). The total residence 

time is estimated at 36 hours for the sugar fermentation. It is expected that saccharification will 

continue in the fermentors, slowed by the lower temperature, but perhaps enhanced by the 

removal of glucose. This SSCF aspect is not modeled. In all, five vessels are required for this 

residence time and are arranged in a continuous train. Table 11 summarizes the conditions in the 

fermentation vessels. 

31 
Table 11. Co-Fermentation Conditions 

Organism Zymomonas mobilis strain 

Temperature 41°C 

Initial Fermentation Solids Level 20% total solids 

Residence Time 1.5 days 

Size of Vessels 3,596 m3

 (950,000 gal) each 

Number of Vessels 5 

Number of Continuous Trains 1 

Inoculum Level 10% 

Corn Steep Liquor (CSL) Level 0.25% 

Diammonium Phosphate (DAP) Level 0.33 g/L fermentation broth 

Inoculum from the seed train at a ratio of 1/10th of the hydrolyzate is fed along with corn steep 

liquor, added as a nutrient at a rate of 0.25%39, and Diammonium Phosphate (DAP), added as a 

nutrient at a rate of 0.33 g/L40. Table 12 lists the reactions and conversions in fermentation. 

Fermentation of the other hemicellulosic sugars (arabinose, mannose, and galactose) is assumed 

to have the same reactions and conversions as xylose. 

Table 12. Co-Fermentation Reactions and Conversions 

Reaction Reactant Fraction

Converted 

to Product 

Glucose → 2 Ethanol + 2 CO2 Glucose 0.95 

Glucose + CSL + 

0.018 

DAP 

→ 6 Z. mobilis + 2.4 

H2O 

+ 0.3 O2 Glucose 0.02 

Glucose + 2 H2O → 2 Glycerol + O2 Glucose 0.004 

Glucose + 2 CO2 → 2 Succinic Acid + O2 Glucose 0.006 

Glucose → 3 Acetic Acid Glucose 0.015 

Glucose → 2 Lactic Acid Glucose 0.002 

3 Xylose → 5 Ethanol + 5 CO2 Xylose 0.85 

Xylose + 0.835 

CSL + 

0.015 

DAP 

→ 5 Z. mobilis + 2 H2O + 0.25 O2 Xylose 0.019 

3 Xylose + 5 H2O → 5 Glycerol + 2.5 O2 Xylose 0.003 

Xylose + H2O → Xylitol + 0.5 O2 Xylose 0.046 

3 Xylose + 5 CO2 → 5 Succinic Acid + 2.5 O2 Xylose 0.009 

2 Xylose → 5 Acetic Acid Xylose 0.014 

3 Xylose → 5 Lactic Acid Xylose 0.002 

Corn steep liquor (CSL) and Diammonium Phosphate (DAP) are both nitrogen sources required for Z. 

mobilis growth. The usage rates for these nutrients are the same as used in laboratory fermentations; 

however the stoichiometry used to model the reactions has not been experimentally verified. 

In addition to fermenting sugars to ethanol, sugars are converted to other products because of the 

presence of contaminating organisms. A total of 3% of the sugars available for fermentation are 

assumed lost to contamination.41 This is modeled as a side stream (bypassing fermentation) 

where sugars are reacted to form lactic acid. This allows the model to simply assign a percent 

32 
loss to contamination and the conversions in the fermentor model do not have to be adjusted. 

Table 13 shows the only contamination reactions. 

Table 13. Co-Fermentation Contamination Loss Reactions 41 

Reaction Reactant Fraction

Converted 

to Product 

Glucose → 2 Lactic Acid Glucose 1.0 

3 Xylose → 5 Lactic Acid Xylose 1.0 

3 Arabinose → 5 Lactic Acid Arabinose 1.0 

Galactose → 2 Lactic Acid Galactose 1.0 

Mannose → 2 Lactic Acid Mannose 1.0 

The fermenters are cooled using a pump-around loop that consists of a centrifugal pump P-300 

and heat exchanger, H-300. The heat exchanger is generally cooled with well water at 13°C. 

When the well water is not sufficient for complete cooling, it is supplemented by cooling water. 

At the end of the fermentation train, a beer well (T-306) collects the fermented beer and scrubber 

bottoms. With a residence time of four hours (recommended by Vogelbusch42), this tank allows 

for some surge capacity between fermentation and distillation. The effective ethanol 

concentration in the fermentation train is 5.7%; a minor amount of this is entrained in the CO2 

vent stream. 

II.3.3 Cost Estimation 

In general, the material of construction for all equipment in this section is 304SS, which is the 

most cost-effective material for the fermentation service. 

We estimated all centrifugal pumps for this section using the ICARUS23 cost estimation software. 

Costs of the rotary lobe pumps (P-301 and P-302) were obtained as verbal quotations from 

Waukesha Pump Company. 

The cost for the major agitators, those for the larger fermenters (A-300, A-310) and other large 

applications (A-301, A-305), were based on vendor (Lightnin Corp.) quotes that Delta-T had 

obtained for a different project. The large agitators are side-mounted. This minimizes additional 

structural steel required for top-mounted agitator supports. These quotes were scaled using a 

scaling exponent from Garrett

6

 to fit the size required here. We used ICARUS to estimate the 

smaller agitators (A-304, A-306). 

We obtained a quotation from Chattanooga Boiler and Tank Co. for the larger vessels 

(saccharification tanks, fermenters and seed hold tank (T-310, F-300, F-305, and T-301)). The 

smaller seed fermenters (F-301, F-302, and F-303) were estimated with ICARUS as jacketed, 

agitated packaged units. The other, medium-size tanks (F-304, T-306) were estimated with 

ICARUS as stand-alone tanks. 

Several plate and frame heat exchangers in this area (H-300, H-301, and H-302) were costed by 

Delta-T from previous jobs. In the case of H-300, the cost from ICARUS was exactly the same 

as Delta-T’s number and is used here. The seed fermenter coil coolers (H-304 and H-305) were 

costed with ICARUS. 

33 
II.3.4 Achieving the Design Case 

Table 14 summarizes the experimental and design case conditions for the saccharification area. 

The research to date has been with SSCF at lab scale to test enzyme activity, since the optimized 

enzymes are not yet available. 

Table 14. Experimental Saccharification Conditions 

Experimental43 Design Case

Mode SSF Saccharification 

Temperature 32°C 65°C 

Initial Saccharification Solids Level 6% cellulose 22% total solids 

Residence Time 7 days 1.5 days 

Size of Vessels Shake flask 3596 m3

 (950,000 gal) each 

Number of Vessels N/A 5 

Number of Continuous Trains N/A 1 

Cellulase Loading 15 FPU/g cellulose 12 FPU/g cellulose 

Table 15 shows the reactions and experimental saccharification conversions for corn stover as 

measured using NREL’s SSF experimental protocols. These conversions are used in the design 

case. The 90% cellulose to glucose yield has been achieved at 15 FPU/g cellulose in an SSCF 

mode and is considered achievable at a lower enzyme loading of an optimized enzyme. A 

separate saccharification step will allow better use of temperature to optimize enzyme 

performance. 

Table 15. Experimental Saccharification Reactions and Conversions 

Reaction Reactant Fraction Converted to Product

Experimental43 Design Case

(Glucan)n → n Glucose Oligomer Glucan 0.04 0.04 

(Glucan)n + 1⁄2n H2O → 1⁄2n Cellobiose Glucan 0.012 0.012 

(Glucan)n + n H2O → n Glucose Glucan 0.90 0.90 

Cellobiose + H2O → 2 Glucose Cellobiose 1.0 1.0 

The seed train in NREL’s pilot plant is similar to that outlined in the design, and has been run 

successfully to grow yeast for several campaigns, each lasting several weeks. 

Table 16 summarizes the experimental and design case conditions for co-fermentation. The 

experimental conditions are from a yellow poplar run. This fermentation is reported because no 

fully mass-balanced fermentations using pretreated corn stover have been run to date. 

34 
Table 16. Experimental Co-Fermentation Conditions 

Experimental44 Design Case

Mode SSCF Co-fermentation 

Organism Zymomonas mobilis 39676-pZB4L Zymomonas mobilis strain 

Temperature 32°C 41°C 

Initial Fermentation Solids Level 12.6% 20% 

Residence Time 7 days 1.5 days 

Size of Vessels ~800 mL working volume fermenters 3596 m3

 (950,000 gal) each 

Number of Vessels N/A 5 

Number of Continuous Trains N/A 1 

Inoculum Level 0.5 OD ~ 10% 10% 

Corn Steep Liquor (CSL) Level 0.25% (clarified) 0.25% 

Diammonium Phosphate (DAP) Level 0.33 g/L fermentation broth 0.33 g/L fermentation broth 

Table 17 shows experimentally measured fermentation yields for glucose and xylose from the 

yellow poplar run44 and the design case conversions. The conversions of sugars to other products 

resulting from Z. mobilis metabolism are also listed. 

Table 17. Experimental Co-Fermentation Reactions and Conversions 

Reaction Reactant Fraction Converted to Product

Experimental44 Design 

Case

Glucose → 2 Ethanol + 2 CO2 Glucose 0.95 0.95 

Glucose + CSL + 

0.018 

DAP 

→ 6 Z. mobilis + 2.4 

H2O 

+ 0.3 O2 Glucose 0.02 0.02 

Glucose + 2 H2O → 2 Glycerol + O2 Glucose 0.004 0.004 

Glucose + 2 CO2 → 2 Succinic Acid + O2 Glucose Not measured 0.006 

Glucose → 3 Acetic Acid Glucose 0.015 0.015 

Glucose → 2 Lactic Acid Glucose 0.002 0.002 

3 Xylose → 5 Ethanol + 5 CO2 Xylose 0.902 0.85 

Xylose + 0.835 

CSL + 

0.015 

DAP 

→ 5 Z. mobilis + 2 H2O + 0.25 O2 Xylose 0.019 0.019 

3 Xylose + 5 H2O → 5 Glycerol + 2.5 O2 Xylose 0.003 0.003 

Xylose + H2O → Xylitol + 0.5 O2 Xylose 0.046 0.046 

3 Xylose + 5 CO2 → 5 Succinic Acid + 2.5 O2 Xylose Not measured 0.009 

2 Xylose → 5 Acetic Acid Xylose 0.014 0.014 

3 Xylose → 5 Lactic Acid Xylose 0.002 0.002 

Corn steep liquor (CSL) and Diammonium Phosphate (DAP) are both nitrogen sources required for Z. mobilis growth. 

The usage rates for these nutrients are the same as used in laboratory fermentations; however the stoichiometry used to 

model the reactions has not been experimentally verified. 

High glucose and xylose to ethanol yields been achieved on yellow poplar feedstock using Z. 

mobilis in the laboratory. However, an engineered organism may not achieve a xylose to ethanol 

yield that high in a less controlled fermentation, so the conversion was lowered slightly in the 

model. Organism development is a crucial activity in enabling fermentation of not only xylose at 

35 
high levels, but also the other sugars including the minor hemicellulose sugars: arabinose, 

mannose and galactose. Tolerance to compounds in the hydrolyzate, particularly acetic acid, may 

also be a key activity in strain development. 

II.4 Cellulase Enzyme 

Area 400, which was used for enzyme production in the 1999 hardwood design1

, has been 

removed. Enzyme will instead be purchased at an estimated cost of $0.10 per gallon of ethanol. It 

will be produced on-site through licensing agreements with enzyme suppliers. This cost was 

developed from our current collaborations with enzyme manufacturers to develop commercially 

available enzyme preparations for lignocellulosic biomass. This equates to $0.17 per gallon of 

cellulose-derived ethanol. If the xylose to ethanol yield is improved, the overall cost of enzyme 

decreases, but the cost per gallon of cellulose-derived ethanol stays constant. If the cellulose to 

ethanol yield is improved, both values will change. 

II.5 Product, Solids, and Water Recovery (Distillation, Dehydration, 

Evaporation, and Solid-Liquid Separation) – Area 500 (PFD-P110-A501-5) 

II.5.1 Overview 

Distillation and molecular sieve adsorption are used to recover ethanol from the raw fermentation 

beer and produce 99.5% ethanol. Distillation is accomplished in two columns—the first, called 

the beer column, removes the dissolved CO2 and most of the water, and the second concentrates 

the ethanol to a near azeotropic composition (see Figure 12). 

All the water from the nearly azeotropic mixture is removed by vapor phase molecular sieve 

adsorption. Regeneration of the adsorption columns requires that an ethanol water mixture be 

recycled to distillation for recovery. 

Fermentation vents (containing mostly CO2, but also some ethanol) as well as the beer column 

vent are scrubbed in a water scrubber, recovering nearly all of the ethanol. The scrubber effluent 

is fed to the first distillation column along with the fermentation beer. 

The bottoms from the first distillation contain all the unconverted insoluble and dissolved solids. 

The insoluble solids are dewatered by a Pneumapress pressure filter and sent to the combustor 

(Area 800). The liquid from the pressure filter that is not recycled is concentrated in a multiple 

effect evaporator using waste heat from the distillation. The concentrated syrup from the 

evaporator is mixed with the solids being sent to the combustor, and the evaporated condensate is 

used as relatively clean recycle water to the process. 

Because the amount of stillage water that can be recycled is limited, an evaporator is included in 

the process. The total amount of the water from the pressure filter that is directly recycled is set 

at 25%. Organic salts like ammonium acetate or lactate, corn steep liquor components not 

utilized by the organism, or inorganic compounds in the biomass end up in this stream. 

Recycling too much of this material can result in levels of ionic strength and osmotic pressures 

that can be detrimental to the fermenting organism’s efficiency. In a typical grain-to-ethanol 

facility, this recycle can be limited to as little as 10% of the centrifuge filtrate stream to minimize 

this effect. For the water that is not recycled, the evaporator concentrates the dissolved solids into 

a syrup that can be sent to the combustor, minimizing the load to wastewater treatment. 

36 
Figure 12. Distillation System Overview, PFD-P110-A500 

37 
II.5.2 Design Basis 

Beer from the fermentation area is first preheated with flash vapor from the pretreatment reactor 

(H-201). This feed to the beer column (PFD-P110-A501) is then further heated by heat exchange 

with the bottoms from the beer column in H-512. The beer column (D-501) operates in a mode to 

remove the CO2 and as little ethanol as possible overhead, while removing about 90% of the 

water to the bottoms. The ethanol is removed as a vapor side draw from the column and fed 

directly to the rectification column (D-502). 

This separation (D-501) is accomplished with 32 actual trays at 48% efficiency with the feed 

entering on the fourth tray from the top. Nutter V-grid trays are used for this purpose. These trays 

have been found to tolerate the solids well and have a relatively good efficiency. Both columns 

(D-501 and D-502) are operated below 2 atm (30 psia) overhead pressure. This relatively low 

pressure keeps the reboiler temperature down and minimizes fouling. The tray spacing is 0.61 m 

(24 in.) and the column diameter is 4.37 m (14.3 ft). The reflux ratio required is 3:1. The 

overheads are vented to the scrubber and contain 83.7% CO2, 12% ethanol, and 4% water. All 

the CO2 and only 0.2% of the ethanol are vented here. Most of the ethanol vented (99%) will be 

recovered and recycled via the vent scrubber. In addition, about 0.7% of the ethanol fed is lost in 

the bottoms stream. Over 99% of the ethanol fed is removed as a 39.4% w/w mixture with water 

vapor side draw from the column at actual tray 8. Heat is supplied to a forced recirculation 

reboiler (H-501) by low-pressure (4.4 atm [65 psia]) steam. A forced circulation reboiler is used 

in an effort to accommodate the solids present in the bottoms. A spare reboiler, suggested by 

Vogelbusch42 to allow for cleaning due to the high-fouling service, is included in the design. 

The vapor side draw from D-501 is fed directly to D-502, the rectification column (PFD-P100-

A502). This column uses 60 Nutter V-Grid trays at a slightly higher efficiency of 57%. The D501 vapor is fed on Tray 44 (from the top) and the recycle from adsorption, which is higher in 

ethanol (72% w/w versus 40% w/w), is fed on Tray 19 (from the top). The column above Tray 

44 is 3.5 m (11.5 ft) in diameter; below Tray 44 it is 1.2 m (4 ft) in diameter. The required reflux 

ratio is 3.2:1 to obtain a vapor overhead mixture of 92.5% w/w ethanol and a bottoms 

composition of 0.05% w/w ethanol. Only 0.1% of the ethanol from fermentation is lost in the 

bottoms. The composition of 7.5% water in the feed to the adsorption column represents only 

0.7% of the water originally entering distillation. Reflux for this distillation is supplied by 

interchange with the evaporator (E-501). An ancillary condenser (H-505) is supplied for start-up. 

Heat is supplied to the column in a thermosyphon reboiler (H-502) with low-pressure (4.4 atm 

[65 psia]) steam. 

As mentioned in Section II.5.1, all ethanol-containing vents are collected and sent through a 

water scrubber (T-512). This is a packed column using Jaeger Tri-Pack plastic packing, and it 

recovers 99.5% of the ethanol with four theoretical stages and 7.6 m (25 ft) of packing. A flow 

rate of about 0.60 m3

/min (158 gpm) of well water is used. The resulting effluent is 1.3% w/w 

ethanol and is sent to the beer well for feeding to D-501. The design basis is >98% ethanol 

adsorption in the vents and venting no more than 36.3 MT (40 ST) per year of VOC for air 

pollution considerations, specifically New Source Performance Standards criteria. 

Overhead vapor from D-502 is fed to the Delta-T molecular sieve adsorption unit (M-503). The 

specifics of the design of this unit are proprietary to Delta-T, but the general arrangement is given 

on PFD-P110-A503. Saturated vapor from the distillation is first superheated and fed to one of 

two adsorption columns. The adsorption column removes 95% of the water and a small portion 

of ethanol. The 99.5% pure ethanol vapor is cooled by heat exchange against regenerate 

condensate and finally condensed and pumped to storage. While one bed is adsorbing water, the 

38 
other is regenerating. Passing a very small slipstream of pure ethanol vapor back through the 

loaded bed while a vacuum is applied carries out regeneration. The water is stripped off the 

adsorbent, and the mixture is condensed and returned to the rectification column (D-502). 

Finally, the beer column (D-501) bottoms are sent to the first effect evaporator (E-501, PFDP110-A504). This effect is heated by both condensing the reflux vapor to the rectification 

column (D-502) and by adding very low-pressure steam (1.7 atm [25 psia]). This dual heating is 

accomplished using a split tubesheet evaporator that prevents the steam from mixing with the 

reflux. About 24% (35% of the total evaporation) of the water entering this first effect is 

evaporated. In addition, the slurry is cooled from 117°C to 87°C, which is a more suitable 

temperature for liquid-solid separation. The slurry is sent to the Pneumapress (S-505, PFD-P110-

A505) and the filtrate is returned to the second evaporator effect (E-502). No washing is used in 

this application of the Pneumapress; otherwise its operation is as described in Section II.2.2. In 

the second effect, 44% (33% of the total evaporation) of the water entering is evaporated. A third 

stage of evaporation (E-502) is used to evaporate 76% of the remaining water (32% of the total 

water evaporated). The final vapor is condensed in H-517. Of the total feed to the 

evaporator/separation system, 10.5% remains as syrup, 11.5% is removed as a wet cake in the 

pressure filter, 17% is recycled back to the process as recycle water, and 61% is evaporated. The 

final syrup (evaporator bottoms) is 60% water. Delta-T estimates that 60% water is the maximum 

dissolved solids level that can be achieved without rapid fouling of the evaporator, so the flow of 

very low-pressure steam to the evaporator is set to achieve this level. This syrup is mixed with 

the solids from the Pneumapress and sent to the combustor for disposal. Air from the 

Pneumapress is sent to the combustor as combustion air. The pressure of the third effect is set by 

the need to easily condense the evaporator vapor with cooling water at 0.21 atm (3 psia) or 64°C. 

The system uses high circulation pumps to minimize fouling on the heat transfer surfaces caused 

by solids adhering to or plating out on the hot surfaces. The pressures of the first and second 

effects were adjusted to make all five evaporators the same size: two units each are used for the 

first and third effects and one unit for the second effect. 

The clean-in-place system services the equipment that handles stillage (beer column bottoms) by 

flushing with a hot caustic solution and recirculating the solution until heat transfer surfaces are 

clean. Manual acid cleaning, which must be performed occasionally, removes mineral scales. 

The frequency for this cleaning depends on the operating conditions. 

Appendix I contains a discussion of the physical property model and parameters used for 

distillation. 

II.5.3 Cost Estimation 

The material of construction for equipment in the distillation area is generally 304SS. We used a 

correlation from Aersten and Street45 to size the thermosyphon reboiler. The pumps, reflux 

drums, and the thermosyphon reboiler (H-502) were costed using ICARUS23. Delta-T used 

information and experience gained in other projects to cost the rest of the equipment. The cost of 

the first evaporator effect (E-501) was increased by 25% to account for the complexity of two 

vapor feeds. Delta-T provided the quote for the molecular sieve package since they are a vendor 

of that equipment. Pneumapress Filter Corporation provided quotes for the pressure filters via 

Harris. 

39 
II.6 Wastewater Treatment (WWT) – Area 600 (PFD-P110-A601-2) 

II.6.1 Overview 

The wastewater treatment section treats process water for reuse to reduce the plant makeup water 

requirement. Figure 13 is a simplified flow diagram of the WWT design chosen. It shows that 

the plant wastewater (condensed pretreatment flash vapor, condensate from the hydrolyzate 

Pneumapress vent, boiler blowdown, cooling tower blowdown, CIP waste, and the non-recycled 

evaporator condensate) is initially screened to remove large particles, which are collected in a 

hopper and sent to a landfill. Screening is followed by anaerobic digestion and aerobic digestion 

to digest organic matter in the stream. Anaerobic digestion produces a biogas stream that is rich 

in methane so it is fed to the combustor. Aerobic digestion produces a relatively clean water 

stream for reuse in the process as well as a sludge that is primarily composed of cell mass. The 

sludge is also burned in the combustor. 

In 1998, the wastewater treatment section was thoroughly studied by Merrick Engineering2

. They 

investigated all of the process wastewaters, selected the design, and estimated costs for this 

section. During their investigation of process streams, Merrick developed a map showing all the 

streams entering WWT and used that map for guidance in selecting the best treatment method for 

each. Merrick recommended an integrated evaporation and water recycle design that was 

implemented by NREL and Delta-T engineers into the process design (see Area 500). That 

improvement cut the loading to WWT dramatically. After reviewing the flow rates and waste 

strength of the remaining wastewater streams, Merrick recommended the screening / anaerobic 

digestion / aerobic digestion scheme for all of them. That waste treatment scheme is standard 

within the current ethanol industry and facilities in the 1-5 million gallons (4-19 million liters) per 

day range can be obtained as “off-the-shelf” units from vendors. 

40 
Figure 13. Wastewater Treatment (WWT) Process Overview, PFD-P110-A600 

41 
II.6.2 Design Basis 

Merrick considered several alternate approaches and determined that screening followed by 

anaerobic digestion and aerobic digestion was the best method for all streams to be treated2

. 

Condensed pretreatment flash vapor, condensate from the hydrolyzate Pneumapress vent, boiler 

blowdown, cooling tower blowdown, CIP waste, and the non-recycled evaporator condensate are 

mixed together (stream 612) and flow through a bar screen (S-600) to an equalization basin (T602). Since ASPEN Plus is a steady state modeling program, upsets (including unusual 

suspended solids) are not modeled, and treatment of the resulting wastewater is not accounted for 

in this design. Rain and snow run-off, equipment washing, and other non-process wastewater are 

assumed to flow to the municipal wastewater treatment system. Other intermittent loads (e.g., 

from process spills) were not considered in the design. The flows and loadings to WWT will not 

be at steady state either, so the equalization basin (T-602) is designed for a steady-state residence 

time of over 7 hours allowing dampening of flow problems downstream. The majority of the 

wastewater in the basin is condensate so it is too warm for biological treatment, so it is pumped 

through a heat exchanger (H-602) and cooled to 35°C. 

The cooled stream then flows to the anaerobic digester. The total chemical oxygen demand 

(COD) is calculated for the stream entering anaerobic digestion (613) and is approximately 1,600 

kg/hr (equivalent to 16 g/L). COD is defined as the amount of oxygen that would be necessary to 

combust all soluble organic components within the stream to carbon dioxide, nitrous oxide, and 

water and is used to determine residence time and nutrient requirements for digestion. Although 

insoluble components such as cellulose and xylan may be converted in anaerobic digestion they 

are not converted within the model making the estimate slightly conservative. No insoluble 

components are included in the COD calculation because of uncertainty of their reactivity. 

Merrick reports that ammonium ions are not converted in anaerobic digestion (although they are 

in aerobic digestion) and recommends that they not be included in this first COD calculation. 

However, the calculated COD is within 5% of the experimentally measured COD and the 

ammonium flowrate is low, so ammonium has been kept in the COD calculation46. The 

biological oxygen demand (BOD) is a better predictor of efficacy of anaerobic digestion but it 

cannot be directly related to composition. It is assumed to be 70% of the COD. 

Within anaerobic digestion, 90% of each organic component is converted to methane and carbon 

dioxide. Methane is produced from that organic matter at its maximum yield of 350 L per kg 

COD removed (0.229 kg/kg at 25°C). Carbon dioxide is also produced at a molar ratio of 1 mole 

carbon dioxide produced per 3 moles methane produced. Cell mass is produced at a yield of 30 g 

cell mass for each 1 kg COD that is removed resulting in a 93% removal of COD. Finally, all 

sulfates entering anaerobic digestion are converted to hydrogen sulfide. The anaerobic digesters 

are sized for a conversion rate of 12 g COD per L digester volume per day. Thirty-seven grams 

of nutrients (primarily caustic with some phosphoric acid, urea and micronutrients) are added per 

kilogram of COD to provide other nutrients the anaerobic organisms require. 

Biogas from the digester contains approximately 75% methane and 25% carbon dioxide on a dry 

molar basis. Depending upon the complexity of the feed, the methane fraction may vary from 

50% to 90%; technologies are available that may increase the methane fraction. During standard 

operation, the gas will flow to the combustor providing about 17.1 MMBTU/hr (5,010 kW) or 

2.6% of the total fuel load supplied to the combustor. An emergency biogas flare is designed into 

the process to burn the biogas in case of a process upset in the combustor. 

42 
The liquid from the anaerobic digester is pumped to aerobic lagoons with floating aerators. In the 

aerobic lagoons 90% of the remaining soluble organic matter is converted with 60% producing 

water, carbon dioxide, nitrous oxide, and sulfur dioxide in stoichiometric amounts. The 

remaining 30% is modeled to produce cell mass on a mass basis (i.e., the atoms do not necessarily 

balance but the mass does). With a 93% reduction of the COD in anaerobic digestion followed 

by 90% reduction of the remaining COD in aerobic digestion, the total COD reduction is 99.4%. 

The aerobic lagoons are sized for a conversion rate of 0.55 g COD per liter lagoon volume per 

day and the aerators are sized to provide 50% more oxygen to the lagoon than is required by the 

COD. 

The fully digested material is pumped to a clarifier (T-610) where the insoluble material, 

consisting primarily of cell mass, is separated from the clean liquor. The clean water has a COD 

of about 0.1 g/L and is mixed with process make-up water and recycled to the process (cooling 

tower, CIP, etc). Most of the sludge is recycled to the clarifier to keep the aerobic lagoons’ cell 

mass loading high. The remaining portion is filtered using a belt filter press (S-614) to remove 

most of the water from the solids. To assist in dewatering, polymer is added to the filter press at a 

rate of 1.7 g / kg COD entering aerobic digestion. The pressed solids are primarily cell mass and 

are conveyed to the combustor for disposal. If higher value disposal options can be found (e.g., 

sale as fertilizer) those will be preferable. Filtrate from the filter press is recycled to the aerobic 

lagoons for additional treatment. 

Because the evaporator syrup from area A500 contains 60% water, sending it to the combustor 

might not be the most economical alternative. As an alternative, we considered sending the 

evaporator syrup to wastewater treatment. This would increase the hydraulic and organic load to 

WWT, however it would also decrease the load to (and therefore cost of) the combustor. Another 

alternative is to send the distillation bottoms to WWT and removed the evaporators, which are 

costly. The results of a comparison of these two options against the design case of sending the 

syrup to the combustor are shown in Table 18. 

43 
Table 18. Comparison of Sending Evaporator Syrup to the Combustor or WWT 

Destination of Evaporator Syrup 

Combustor

(Design Case) 

WWT Change

from the

Design 

Case

WWT with no

evaporators 

Change 

from

Design 

Case

Minimum Ethanol Selling Price ($/gal) $1.07 $1.14 +$0.07 $1.10 +$0.03 

Total Operating Costs (cents/gal): 

Other Raw Materials 5.5 6.9 6.9 

Waste Disposal 2.9 2.9 2.9 

Electricity -9.3 -6.0 -7.0 

Fixed Costs 10.9 11.1 10.9 

Capital Depreciation 14.3 14.9 14.2 

Average Income Tax 10.6 10.8 10.4 

Average Return on Investment 25.4 26.4 25.3 

Operating Costs ($MM/yr) 37.9 38.85 +$0.95 38.88 +$0.98 

Capital Cost Breakdown ($MM): 

Distillation and Solids Recovery $21.8 $21.9 $14.6 

WWT $3.3 $10.6 $13.5 

Boiler/Turbogenerator $38.3 $35.5 $36.1 

Utilities $4.7 $4.4 $3.7 

Total Equipment Cost $113.7 $118.3 $113.4 

Total Project Investment $197.4 $203 +$5.6 $193.8 -$3.6 

Model I0203I I0203I_wwt1 I0203I_wwt_2 

As expected, the cost of wastewater treatment went up considerably when syrup was introduced. 

It went up even further when the evaporators were taken out of the process altogether; however, 

eliminating them reduced the capital costs by over $3MM. The capital costs were lowest for the 

case where no evaporators were included, but the annual operating costs were $0.98MM greater 

because more WWT chemicals were required, but more importantly, because less electricity was 

generated when the solids in the syrup were no longer combusted. Thus, the capital savings from 

removing the evaporators does not overcome the added operating costs plus lost revenue. One 

other impact of removing the evaporators is the loss of clean recycle water. The evaporator 

condensate (stream 534A) has no solids and few other impurities (1%). Without evaporators, the 

treated wastewater would be used for recycle water. This stream would have solubles and 

suspended solids in it (that were previously removed by the evaporators), which could adversely 

affect process conversions and equipment efficiency. This comparison shows that the overall 

economics as measured by the cost of ethanol production are most favorable when the syrup is 

sent to the boiler. 

II.6.3 Cost Estimation 

All cost estimations for this area were taken from the Merrick report2

. The primary equipment 

costs in this area are the anaerobic digesters, aerobic lagoons, and the belt filter press. The 

anaerobic digester cost was taken from a quote developed by Chattanooga Boiler and Tank 

Company for the SS304 fermentation vessels. Merrick quoted the aerobic lagoons as fieldexcavated, polymer-lined lagoons. The belt filter press was costed according to a scaled quote 

from Phoenix Biosystems. 

44 
ICARUS23 was used to cost the remaining equipment including pumps, heat exchangers, and 

surge tanks. 

II.7 Product and Feed Chemical Storage – Area 700 (PFD-P110-A701) 

II.7.1 Overview 

This portion of the plant provides for the bulk storage of chemicals used in the process and 

product ethanol. Storage of the biomass feedstock is handled in Section A100 of the process. 

Feed chemicals stored in this area include CSL, sulfuric acid, cellulase enzyme, propane (for 

feedstock handling forklifts), and gasoline (used as a denaturant for the product ethanol). Water 

for fire suppression is also stored here. 

II.7.2 Design Basis 

Ethanol product storage is based on Delta-T’s experience with fuel ethanol production facilities. 

The recommended amount of storage (T-701) corresponds to 7 days of production or 4,540 m3 

(1.2 million gal) in two 2,270 m3

 (600,000 gal) carbon steel tanks. 

Based on Delta-T’s experience we used 5 days of storage for sulfuric acid (T-703), which 

corresponds to about 72 m3

 (19,000 gal). Stainless steel (SS316) is used as the material of 

construction because of the corrosive nature of sulfuric acid. SS316 is the industry standard for 

ambient temperature sulfuric acid. 

Using a flow rate of 568 m3

/hr (2,500 gpm) of fire-fighting water (similar to another Delta-T 

project of about the same size), 2,270 m3

 (600,000 gal) tank supplies 4 hr of operating time. The 

tank (T-704) is of carbon steel construction. 

Corn steep liquor (CSL) is a nutrient source for fermentation seed growth and ethanol production. 

The storage time is 5 days or a 273 m3

 (72,000 gal) tank (T-720). The tank is stainless steel 

(SS304) construction. CSL would likely be supplied by rail car. Standard rail tank car capacities 

range from 8,000 to 30,000 gallons with typical loads between 20,000 and 25,000 gallons

47 for 

products such as corn syrup, resins, oils, fertilizers, and petroleum. Therefore, 3 tank cars of CSL 

would be needed every 5 days. 

Diammonium Phosphate (DAP) comes in solid form, probably pellets, via rail car. The usage 

rate of 4 MT per day will require solids handling and storage equipment similar to that for the 

lime in Area 200. The DAP storage bin (T-755) was sized at 40 m3

 (10,500 gal) based on a 7-day 

storage time. From the storage bin, DAP is fed into a day tank (T-760) where it is mixed with 

CSL. The CSL/DAP mixture is then pumped to fermentation seed production and ethanol 

production. 

Liquid cellulase enzyme is received from an enzyme producer either on-site or close-by. The 

storage time is set at 4 days in two 500 m3

 (130,000 gal) tanks (T-750), which allows enzyme lots 

to be kept separate and identified. The tanks are stainless steel (SS304) construction. 

Propane fuel for the forklifts is delivered in 7.6 m3

 (2,000 gal) trucks. A 33-lb propane tank, 

which fuels the forklift, lasts approximately 8 hours according to the vendor

48. Therefore, the 

45 
approximate consumption rate of propane for 8 forklifts is 0.022 ft

3

/min (33 lb/hr). A 13 m3 

(3,435 gal) tank (T-709) gives about 15 days of storage. This tank is pressurized to 250 psig. 

Gasoline is used as a denaturant for the ethanol being loaded for transportation away from the 

plant. Five percent gasoline (v/v) is added to the ethanol. A 7-day storage time is used for the 

gasoline as for ethanol, or 241 m3

 (63,600 gal) tank (T-710). Carbon steel is used for this tank. 

The pumps in this section are generally sized for quickly loading trucks (P-701, P-710) or filling 

process day tanks (P-703 and P-720). The firewater pump is sized for 568 m3/hr (2,500 gpm). 

Other pumps are sized per the process requirements. 

II.7.3 Cost Estimation 

We used ICARUS to estimate the cost for all equipment in this section23. 

II.8 Combustor, Boiler, and Turbogenerator – Area 800 (PFD-P110-A801-3) 

II.8.1 Overview 

The purpose of the combustor, boiler, and turbogenerator subsystem is to burn various by-product 

streams for steam and electricity generation. All of the lignin and some of the cellulose and 

hemicellulose from the feedstock will remain unconverted through the hydrolysis process. The 

majority of wastewater from the process is concentrated to a syrup high in soluble solids. 

Anaerobic digestion of the remaining wastewater produces a biogas high in methane. Aerobic 

digestion produces a small amount of waste biomass (sludge). Burning these by-product streams 

to generate steam and electricity allows the plant to be self sufficient in energy, reduces solid 

waste disposal costs, and generates additional revenue through sales of excess electricity. 

Reaction Engineering Inc. (REI)3

 investigated the combined system of combustor, boiler, and 

turbogenerator. They contacted several vendors to obtain cost and operating information to 

identify a system suitable for the available fuel streams and steam requirements. REI also 

obtained quotes for support equipment including a deaerator, baghouse, and boiler feedwater 

pumps. 

Three primary fuel streams (post-distillate solids, biogas, and evaporator syrup) are fed to a 

Circulating Fluidized Bed Combustor (CFBC). The small amount of waste biomass (sludge) 

from wastewater treatment is also sent to the combustor. The post-distillate solids’ moisture 

content leaving the Pneumapress is 45%. The biogas and syrup enter the combustor at 4% and 

60% moisture, respectively. The moisture of the combined feed to the combustor is 52%. A fan 

moves air into the combustion chamber. Treated water enters the heat exchanger circuit in the 

combustor and is evaporated and superheated to 510°C (950°F) and 86 atm (1265 psia) producing 

184,771 kg/hr (407,420 lb/hr) of steam. Boiler efficiency, defined as the percentage of the feed 

heat that is converted to steam heat, is 68% (see Figure 16). Flue gas from the combustor 

preheats the entering combustion air then enters a baghouse to remove particulates, which are 

landfilled. The gas is exhausted through a stack. 

A multistage turbine and generator are used to generate electricity. Steam is extracted from the 

turbine at three different conditions for injection into the pretreatment reactor and heat exchange 

in distillation and evaporation. The remaining steam is condensed with cooling water and 

returned to the boiler feedwater system along with condensate from the various heat exchangers 

in the process. Treated well water is used as makeup to replace steam used in direct injection. 

46 
Makeup water and condensate are softened, deaerated, and preheated with steam to 177°C. 

Chemicals for pH control, scale removal, and oxygen removal are added. Boiler blowdown is 3% 

of steam production. Section II.10.3 discusses the energy balance of the steam cycle. 

II.8.2 Design Basis 

The design of the combustor/boiler/turbogenerator system is changed somewhat from an earlier 

design by Radian Corporation49. The previous design included a drum dryer that used the hot flue 

gas to reduce the moisture in the solids. However, since the Pneumapress pressure filter is 

capable of drying the post-distillate solids more efficiently than the centrifuge previously in the 

design, the drum dryer is no longer required, and the hot flue gas can be used to preheat the 

combustion air (H-801), which improves the boiler efficiency. When combined with maintaining 

a high solids content in the syrup, drying the solids helps to ensure a stable combustion bed 

temperature and improved boiler efficiency. Foster Wheeler Energy (FWE) suggested maximum 

feed moisture of 50%; other sources50 suggest 60% is acceptable. There is a wide range of values 

reported, primarily due to the various combinations of combustor designs and feeds being used. 

Because of heightened interest in using biomass, pulping wastes, and sewage sludge in place of 

fossil fuels, new methods of handling higher moisture feeds are being developed such as in-bed 

drying and staged combustion51. Blending the wet feed with dry material or adding auxiliary fuel 

to maintain the combustion temperature are more traditional methods. A Lower Heating Value 

(LHV) of 1,111-1,389 kcal/kg (2,000-2,500 BTU/lb) is considered a minimum for maintaining 

combustion3

. The combined feed to the combustor has a LHV of 2,322 kcal/kg (4,179 Btu/lb). 

The total energy (on a higher heating value basis) to the combustor in the combined feed streams 

is 178 MMkcal/hr (706 MMBtu/hr). The solids contribute 59% of this energy and the syrup 

contributes 37%. 

Foster Wheeler Energy (FWE)3 confirmed the Radian design49 of a circulating fluidized bed 

combustor (CFBC) (M-803). This type of combustor is suitable for varying feeds and feed 

characteristics; however, this flexibility is more expensive than a grate or pile combustor. 

Because the bed material is returned to the combustor after the cyclone, CFBCs have little 

unburned carbon in the ash. Compared to coal, the combined feed in this process has 

significantly less ash and could require supplementing the bed with sand to keep an adequate bed 

level. Two drawbacks to these units are the high power requirement for circulation and the 

potential for erosion due to high particulate velocities. Parameters for emissions and efficiency 

losses were supplied by FWE. 

Because the steam pressure required by the process is not high (13 atm [191 psia]), NREL 

engineers originally envisioned a lower pressure system. FWE declined to quote on this system, 

citing it as non-standard due to the low operating pressure available to move the water/steam over 

the heating surfaces. After further study, FWE did state that a low-pressure system might be costeffective because the lower materials cost may pay for the cost of added piping on the steam side, 

but they did not provide a cost estimate. 

Another option, gasification of the waste streams to produce steam and electricity, is being 

studied at NREL. Gasification has the potential to produce enough steam and larger amounts of 

electricity through an integrated combined cycle (gas and steam turbine) system than 

conventional combustion with only a steam turbine. 

The turbogenerator (M-811), which consists of a multistage turbine with extraction ports, 

generator, and condenser is the other main portion of this section, producing lower pressure steam 

47 
and electricity. Twenty-eight percent (28%) of the steam is extracted from the turbine at 13 atm 

(268°C [191 psia, 514°F]), 60% at 4.4 atm (164°C [65 psia, 327°F]), and 3% at 1.7 atm (115°C 

[25 psia, 239°F]) for process needs. The remaining steam (9%) is condensed at 0.1 atm (1.5 

psia). ABB Power Generation Systems (ABB) provided cost, efficiency, and design information, 

which were used in the model3

. ABB representatives, when asked about the low-pressure boiler 

discussed above, stated that the lower pressure option did not allow the most cost effective 

turbine system; higher-pressure systems supply more electricity on a power per capital cost basis. 

Badger,52 working with Turbodyne, came to the same conclusion, stating “for larger turbines of 

8000 kW upward steam inlet pressure has little effect on capital costs over the range 200-1600 

psig”. Per ABB, the turbine efficiency was set at 85%. For this design, a total of 30.4 MW of 

power is generated from the system. The process uses 11.7 MW, leaving 18.7 MW that is sold to 

the grid. 

V. Putsche confirmed the FWE and ABB design parameters using an ASPEN combustor/boiler 

model showing good correlation of efficiencies, output flows, and temperatures53. 

The boiler feed water (BFW) system includes a softener (M-820) for the makeup and condensate 

water, a deaerator (T-826) to remove air and other non-condensables, surge tanks and pumps. 

The boiler feedwater pumps (P-826) produce 98 atm (1445 psia) of pressure and require 709 kW 

(951 hp) of power. Liquid hydrazine (T-830, PFD-P110-A804) is injected into the deaerator to 

remove oxygen, which can pit the boiler surfaces. Ammonia, which volatizes with the steam, is 

added to control the pH and reduce the corrosive nature of the hot condensate. Phosphate is also 

added to control the formation of scale in the steam drum. The oxygen, pH, and hardness control 

systems were designed by Badger52 and follow conventional practice54. The amount of water 

treatment necessary depends on the incoming water quality, metallurgy of the boiler, and the ratio 

of makeup to condensate in the feedwater. The current system contains some redundancy; 

however, the control systems’ costs are low compared to the replacement cost of the boiler or its 

components. 

The power usage estimate for the baghouse (M-804) cleaners (176 kW [236 hp]) was obtained 

from the vendor, Hamon Research-Cottrell. One induced draft fan was used to move the flue gas 

from the combustor cyclone through the baghouse. 

Pollutant generation values were taken from information provided by FWE. Baghouse efficiency 

of 98.8% was taken from information supplied by the vendor. All of the emissions are below the 

current New Source Performance Standards (NSPS) limits53 so no control measures other than the 

baghouse were added to the process. Pollutant flow rates are calculated from the generation rates 

discussed below and the higher heating value of the combustion feed stream. 

Sulfur dioxide is assumed to be generated at a rate of 0.68 kg/MWhr (0.44 lb/MMBtu). All of the 

sulfur into the combustor is converted to sulfur dioxide; 1% of the generated sulfur dioxide is 

converted to sulfuric acid. The presence of this acid requires that the flue gas temperature be kept 

above the dew point to avoid corrosion. Sulfur comes from wastewater treatment (hydrogen 

sulfide), neutralization of sulfuric acid, and is present in the proteins within the cellulase and 

biomass entering the boiler with the pressure filter and spent biomass solids, respectively. 

Limestone, if it is needed to control sulfur dioxide to a stricter standard, can be purchased for 

about $6 per ton for quarter-inch particle size.3

 The amount of sulfur in the combustor feed 

streams is higher than untreated biomass, but lower than most coals. 

Carbon monoxide is assumed to be generated at a rate of 0.31 kg/MWhr (0.2 lb/MMBtu).3 

Unburned carbon (char) in the ash is low at 1%, owing to the circulation of the unburned carbon 

48 
back to the combustor bed from the cyclone. The flue gas composition of 804D on PFD-P110-

A801 shows the remaining unreacted components; in actuality, these would be present in the flue 

gas as char. 

NOx is generated at 0.31 kg/MWhr (0.2 lb/MMBtu)3

. Nitrogen oxide, or NOx, formation is a 

complicated mechanism, and depends on the feed, combustion temperatures, excess air rate, 

combustor design and the presence of other control schemes like limestone injection for sulfur 

dioxide control. CFBCs are generally considered to have lower NOx emissions due to lower 

combustion temperatures compared to traditional pile or grate combustors50. The fate of the 

ammonia species in a combustor is not well understood, but there is evidence to suggest that 

some of the ammonia is converted to nitrous oxide (N2O) while also acting to reduce NOx 

formation.

55 Ammonia injection has long been a means of reducing NOx emissions. The nitrogen 

level in the combined feed is similar to coal when the ammonia species are included, but is more 

like untreated biomass when they are not. 

II.8.3 Cost Estimation 

The costs for the CFBC, turbogenerator, boiler feedwater pumps, and deaerator are from vendor 

quotes. In addition, FWE and ABB provided scaling factor information. According to FWE, the 

CFBC should be scaled on steam production, but only for similar feed conditions such as 

moisture content. The cost obtained from FWE compared well with a previous 1994 quote, 

shown in Table 19. Other quotes obtained over the last decade are also listed in this table. 

Boiler feedwater softening equipment was costed using Richardson56, including the scaling factor. 

Other chemical treatment costs are from Chem Systems

57. ICARUS23 was used to cost the 

remaining equipment including pumps, heat exchanger, and surge tanks. 

For the baghouse, information on bag life and replacement cost from the vendor was incorporated 

into the capital costs. 

Table 19. Boiler Costs 

Vendor/Requestor Year Steam

Conditions 

Pressure/Temp 

Steam

Production 

(1000 lb/hr) 

Total Cost

($MM)* 

Scope 

FWE/REI3 1998 915-1265 

psia/950°F 

752 24.9 CFB 

FWE/NREL 58 1994 1515 psia/950°F 694 22.9 CFBC 

Ahlstrom 

Pyropower/Radian49 

1991 1515 psia/950°F 279-385 18-24 FBC 

ABB/Chem 

Systems

59 

1990 1100 psia/875°F 434 19.8 Dryer/ 

FBC 

*$1998 dollars 

49 
II.9 Utilities – Area 900 (PFD-P110-A901-3) 

II.9.1 Overview 

This area provides all utilities required by the ethanol production facility except steam and 

electricity, which are provided by Area 800. The utilities provided include cooling water, chilled 

water, plant and instrument air, process water, and the clean-in-place (CIP) system. 

Cooling water is provided to the following equipment items: 

• H-200 to cool the pretreated hydrolyzate liquor before it enters overliming 

• H-205 to condense the water from the Pneumapress air vent 

• H-244 to cool the pretreatment flash vapor before it enters WWT 

• F-301-5 on an as-needed basis to remove heat in the seed train 

• H-300 on an as-needed basis to remove heat produced in the co-fermentation production train 

• H-302 to cool the saccharified slurry to fermentation temperature 

• H-310 to remove heat produced in the saccharification production train 

• H-504 to condense the beer column reflux 

• H-505 to condense the rectification column reflux during start-up 

• H-517 to condense vapors from the third evaporator effect 

• M-503 to provide some cooling and condensation in the molecular sieve 

• H-602 to cool wastewater before anaerobic digestion 

• M-811 to condense the remaining steam after the steam turbine 

No chilled water is used in the plant; the required process temperatures can be achieved by 

cooling water year-round. 

The plant and instrument air systems provide compressed air for plant uses (pneumatic tools and 

clean up), the Pneumapress units (prehydrolysis conditioning and post-distillation dewatering), 

and instrument operation. 

The process water system mixes fresh well water with treated wastewater and provides water at a 

constant pressure to the facility. Water is provided to the stover washer system, seed production, 

boiler feed water, cooling tower make-up, the CIP system, and the scrubber. It is also mixed with 

recycle water for dilution before saccharification. Process water is also used throughout the 

facility for cleaning on an as-needed basis. 

The CIP system provides a solution that can be heated and includes cleaning and sterilization 

chemicals to saccharification and co-fermentation, seed vessels, and the distillation system. 

II.9.2 Design Basis 

The primary cooling water consumers in this process are pretreatment, saccharification, 

fermentation, distillation, wastewater treatment, and steam condensation after the turbogenerator. 

The cooling water system is designed at 28°C with a 9°C temperature rise in coolers throughout 

the facility. We chose 28°C because the average summer wet bulb temperature in the 

southeastern part of the United States is 25°C and a 3°C approach is a reasonable design60. 

50 
Overliming, saccharification, fermentation, distillation, wastewater treatment, and steam 

condensation in the boiler utilize cooling water year round. The initial cooling source for 

fermentation, which is operated at 41°C, is well water, which enters the facility at 13°C and is 

heated to 26°C by the fermentation cooling load before entering the process water system. The 

remaining heat is removed by cooling water. 

Using ASPEN, we calculated the amount of cooling tower evaporation and assumed that windage 

would be 0.1% of the total flow to the tower. The tower blowdown is assumed to be 10% of the 

sum of the evaporative loss plus windage. 

The plant and instrument air systems provide compressed air for plant uses (pneumatic tools and 

clean-up, Pneumapress filters) and instrument operation. Delta-T recommended 1,530 m3

/hr (900 

SCFM) compressed air for plant operation. The plant air compressor also provides air at 9.5 atm 

(140 psia) to the Pneumapress filters via air receivers at a combined usage of 8,892 m3

/hr (5,230 

ACFM). Three 5,228 m3

/hr (3,075 CFM) screw compressors were specified—two on-line with 

one spare. An instrument air dryer and a surge tank were designed to provide clean dry air at a 

consistent pressure to the instrument air system. The surge tank was sized at 3.8 m3

 (1,000 gal) to 

provide about 2.5 L/m3

/hr (1 gal per SCFM) of compressor capacity. 

Fresh well water is used to cool the fermentation broth and is then split three ways, to provide 

clean water to the boiler feed water make-up system and the scrubber. The process water tank (T914) mixes and holds the treated wastewater and the remaining fresh water before it is pumped 

throughout the facility. It is designed for an 8 hr. residence time. The process water pump (P914) pumps water from the tank into the facility. It is designed to handle 1.5-times the process 

water flow requirement. The scrubber and the boiler feedwater system require fresh water. Fresh 

process water is mixed with recycle water for dilution prior to entering seed production, cooling 

tower make-up, and the CIP system. 

The CIP system is designed to provide cleaning solution to all the seed, saccharification and 

fermentation tanks, to the beer column, to all the beer column heat exchangers, and to the 

evaporators. 

Process water flows into the CIP system tanks and is heated by low-pressure steam. Two CIP 

tanks are needed in order to maintain the ability to clean a tank at the same time as a beer column 

component. 

The washing sequence follows: 

1) Process water is pumped at 454 m3

/hr (2,000 gpm) (or at the equipment design flow) 

to the equipment being cleaned in order to flush the solids out of the equipment. 

2) a. CIP solution is then pumped at 454 m3

/hr (2,000 gpm) (or at the equipment 

design flow) through the equipment and returned to the CIP tank via the cyclone 

separator. 

b. For tanks with spray balls, CIP solution is pumped at 136 m3

/hr (600 gpm) 

through the spray balls in the tank. The solution is then pumped back to the CIP 

tanks by the 136 m3

/hr (600 gpm) CIP return pump, via the cyclone separator. 

3) The cyclone separator continuously discharges the sludge stream to the wastewater 

treatment area while the centrate is returned to the CIP tank for reuse. 

4) The CIP cycle continues until the equipment has been cleaned. 

51 
II.9.3 Cost Estimation 

We based the cooling system cost estimate on a verbal quote by Marley. It was quoted for a heat 

load of 148 MM Kcal/hr (587 MMBtu/hr) and fiberglass construction for cost effectiveness and 

corrosion resistance. The quoted cooling tower is a five cell counterflow tower with a 82.3 m x 

16.8 m (270 ft x 55 ft) frame, a 82.6 m x 18.6 m (271 ft x 61 ft) basin, a 181 kW (243 hp) fan in 

each cell, and a total flow capacity of 16,125 m3

/hr (71,000 gpm). The cooling tower circulation 

pumps were estimated using ICARUS23. Their material of construction is carbon steel, chosen 

because of Delta T’s experience with these towers. 

We used ICARUS to estimate the plant and instrument air compressor and dryer costs. The 

estimates are based on 125-psig rotary screw compressors and a dew point requirement of -40°C. 

We used ICARUS to estimate the plant air receiver tank costs as a horizontal vessel with a design 

pressure of 14.6 atm (200 psig). The Pneumapress air receivers were costed by Harris19. 

The process water tank and pump costs were estimated using ICARUS. We estimated the tank 

cost using the atmospheric pressure carbon steel vertical vessel data and the pump cost using the 

carbon steel centrifugal pump data. 

The CIP system was designed by Delta-T and the cost was estimated to be similar to the costs 

previously used by NREL for this system. The cost of the previous units totaled $95,000 (1995). 

Scaling and installation factors were estimated. 

II.10 Water and Carbon Balances and Energy Analysis 

II.10.1 Water Balance 

Large amounts of water are circulated throughout the biomass-to-ethanol process. Detailed water 

balances around the major processes and the entire plant were derived from the ASPEN 

simulations. Improving water usage to reduce makeup demand continues to be an area of study. 

The process is designed for zero discharge to a municipal treatment plant in a steady state mode. 

Table 20 shows the major water inputs and outputs to the overall ethanol plant. Well water is 

used to make up for water losses to the atmosphere due to evaporation, water in streams vented to 

the atmosphere, and water entrained in the waste solids. Water is consumed in hydrolysis 

reactions that convert the long chain polymers to monomeric sugars (prehydrolysis and 

saccharification) and generated in the combustion and digestion reactions. The difference in the 

water and overall mass balance is discussed in the next section with the carbon balance. 

52 
Table 20. Ethanol Plant Overall Water Balance 

Total Flow (kg/hr) Water Flow (kg/hr) 

Process Inlets 

Stover Feedstock 98,039 14,706 

Enzymes 6,824 6,255 

Chemicals & Nutrients 7,239 0 

Air 310,255 3,382 

Well Water 186,649 186,649 

Inlet Total 609,006 210,992 

Water Consumption/Generation 

Prehydrolysis -2,788 

Saccharification -2,736 

Combustion 20,035 

Wastewater Treatment 371 

Consumption/Generation Total 14,882 

Process Outlets 

Ethanol Product 24,686 122 

Evaporative Losses 195,993 156,291 

Vents to Atmosphere 375,443 68,051 

Solids to Landfill 12,718 2,194 

Outlet Total 608,840 226,658 

Water Difference (inputs + consumption + generation - outputs) -784 

II.10.2 Carbon Balance 

Overall mass balances are performed on the ethanol production process using ASPEN. As a 

check of our assumed biomass composition, stream flow definitions and reaction stoichiometry 

throughout the process, a carbon balance was performed61. 

The overall carbon balance is 99% closed. The methods used in modeling two subsystems, 

wastewater treatment (T-606) and the treated water mix (T-914), contribute to the small error. 

• T-606 was designed using the COD (chemical oxygen demand) method of wastewater 

treatment, which only ensures that the mass balance closes and not the component molar 

balance. This section accounts for 15 kmol/hr of the discrepancy. 

• T-914 assumes that pure water is being recycled to the plant; therefore the trace carbon 

compounds exiting from the block are not taken into account. Since the total 

concentration of these trace compounds are very low (less than 0.5%) in the recycle 

stream, they are not modeled. This section accounts for the other 25 kmol/hr of the 

discrepancy. 

Table 21 shows the flow of carbon as a percentage of the biomass feed. As shown in the table, 

99% of the carbon enters in the biomass feed. The major exits for carbon (accounting for 99%) 

are in the combustion exhaust (47%), ethanol product (34%), and the scrubber vent (17%). These 

results are depicted in Figure 14. 

53 
Table 21. Ethanol Plant Overall Carbon Balance 

Carbon Flow 

(C kmol/hr) 

Ratio to Feedstock Carbon Content 

(C kmol basis) 

Carbon Inlets 

Stover Feedstock 3,144 1.000 

Enzymes 25 0.008 

Total 3,169 1.008 

Carbon Outlets 

Combustion Exhaust 1,497 0.476 

Ethanol Product 1,066 0.339 

Scrubber Vent 532 0.169 

Ash 16 0.005 

Gypsum 10 0.003 

Aerobic Vent 3 0.001 

Loss to Atmosphere 4 0.001 

Total 3,129 0.995 

We expect the amount of carbon exiting in the combustion exhaust to be rather large because 

most byproducts (lignin etc.) of this process are burned; thus liberating CO2. Over 99% of this 

stream consists of carbon dioxide. The majority of the carbon exiting the scrubber vent is in the 

form of CO2 with some minor amounts of carbon exiting in the form of ethanol (0.05%). The 

scrubber processes the fermentation gas, which contains CO2. 

54 
Figure 14. Process Carbon Balance 

 55 
Table 22. 

Component 

Feed Stream Carbon Composition 

Carbon Flow (C kmol/hr) % Carbon Flow (C kmol basis) 

Ethanol Producing Reactants 

Cellulose 1,154 36.7% 

Xylan 665 21.1% 

Arabinan 92 2.9% 

Galactan 60 1.9% 

Mannan 48 1.5% 

Total 2,019 64.2% 

Non-Ethanol Producing Reactants 

Lignin 968 30.8% 

Soluble Solids 13 0.3% 

Acetate 81 2.6% 

Protein 40 0.8% 

Extractives 26 1.3% 

Total 1,125 35.8% 

The comparison of the ethanol product’s carbon content to that of the total biomass feed is a little 

misleading since the non-carbohydrate components of the biomass cannot be converted to ethanol 

via fermentation. Accordingly, the biomass feed stream can be broken into the various ethanol 

and non-ethanol producing components. Table 22 shows the distribution; 64% (C mole basis) of 

the carbon in the feed stream is present as ethanol producing sugars. Converting all of this carbon 

represents the theoretical yield. According to Table 21, 51% of the feed stream carbon is actually 

converted by the ethanol pathway (ethanol in the product and CO2 in the scrubber vent), so the 

actual yield is 80% of the theoretical yield. 

II.10.3 Energy Analysis 

The process has been analyzed to compare the energy available in its products (ethanol and 

electricity) to the maximum energy available from the biomass feed62. This analysis includes 

other energy inputs to the process (e.g., sensible heat effects of all feed streams and effluent 

streams). 

The potential energy of the material streams is considered to have three contributions: 

1. A chemical potential energy defined as its higher heating value (HHV) at a reference 

temperature of 25°C. 

2. A sensible heat effect to account for the process temperature being different from this 

reference temperature. 

3. A latent heat effect to account for a volatile component being in a phase condition 

different from its phase condition at the reference temperature. (For example, water 

being discharged as a vapor instead of it normal liquid state at 25°C.) 

The potential energies of the material streams are referenced to the potential energy of the 

biomass feed. This is a convenient basis to analyze the energy contents of the streams since the 

energy of the ethanol product will ultimately be recovered by its combustion. One outcome of 

this basis is that combustion products have a zero energy contribution (other than any sensible 

and latent heat effects). Also, the carbon dioxide produced by fermentation essentially has a zero 

energy content compared to the other material and energy streams. 

56 
The HHV is a convenient reference for the combustion energy since there is a lot of liquid water 

flowing throughout the process. The HHV has its basis water produced by combustion in the 

liquid state, not the vapor state (as with the lower heating value, or the LHV). So, the liquid 

water in the process has a zero contribution to the chemical potential energy of any stream. 

A comparison of the major energy streams produced by the process to the combustion energy of 

the biomass feed is made in Table 23 and depicted in Figure 15. The combined energy available 

from the ethanol product and the exported electricity is over half of the energy content of the 

biomass feed. The energy losses from the cooling tower and combustion exhausts are fairly 

large. There is a potential for increased energy recovery as exported electricity if more elaborate 

low level waste heat recovery systems were to be included in the process. 

Table 23. Ethanol Plant Overall Energy Analysis 

Energy Flow 

(MMkcal/hr) 

Ratio to Feedstock 

Energy Flow 

Energy Inlets 

Stover Feedstock 358 1.000 

Enzymes 3 0.009 

Air 2 0.005 

Sulfuric Acid -2 -0.005 

Well Water -2 -0.006 

Other -1 -0.004 

Total 358 1.000 

Energy Outlets 

Ethanol 174 0.487 

Cooling Tower 79 0.220 

Combustion Exhaust 54 0.151 

Ambient Heat and Work Losses 22 0.060 

Byproduct Electricity 16 0.045 

Loss to Atmosphere 1 0.004 

Ash 1 0.003 

Other -2 -0.004 

Total 346 0.966 

Some of the energy flow values in this table are negative. This may be due to the stream’s 

temperature being less than the reference temperature (e.g., the well water enters the process at 

20°C and, as an inlet, represents a sensible heat penalty to the process). The negative value for 

sulfuric acid represents its negative heat of combustion (i.e., heat is required to convert sulfuric 

acid to its combustion products). 

There is a small discrepancy in the overall energy balance for the process. The outlet energy flow 

is 12 MMkcal/hr less than the inlet energy flow. This is due to approximations made in three 

major areas: Pretreatment, Distillation, and Wastewater Treatment. This discrepancy is only 3% 

of the total inlet energy flow. 

There is a small discrepancy in the overall energy balance for the process. The outlet energy flow 

is 12 MMkcal/hr less than the inlet energy flow. This is due to approximations made in three 

major areas: Pretreatment, Distillation, and Wastewater Treatment. This discrepancy is only 3% 

of the total inlet energy flow. 

57 
Figure 15. Process Energy Analysis Based on Higher Heating Value of Biomass Feed 

 58 
As with the carbon balance, a comparison of the ethanol product’s combustion energy content to 

that of the total biomass feed can be misleading. Because the conversion is done by fermentation 

of sugars, the process cannot convert non-carbohydrate components of the biomass (such as the 

lignin and the proteins). The energy content of the various feed components (carbohydrates that 

can be converted to ethanol and the non-carbohydrates that cannot) is shown in Table 24. Only 

63% of the original combustion value of the biomass is due to carbohydrates that can produce 

ethanol. Taking this into account the energy content of the carbohydrates in the feed recovered as 

ethanol is much greater, over 77%. 

Table 24. Feed Stream Energy Analysis 

Component Energy Flow (MMkcal/hr) % Total Feedstock 

Energy Flow 

Ethanol Producing Reactants 

Cellulose 129 36.1% 

Xylan 75 20.8% 

Arabinan 10 2.9% 

Galactan 7 1.9% 

Mannan 5.4 1.5% 

Total 226 63.2% 

Non-Ethanol Producing Reactants 

Lignin 92 25.6% 

Soluble Solids 4 1.1% 

Protein 11 3.1% 

Extractives 17 4.6% 

Acetate 9 2.4% 

Total 132 36.8% 

Similar energy analyses can be performed around any section of the process. An energy analysis 

around the boiler section can identify the relative amount of the energy from the various feed 

streams to the combustor that will ultimately create the steam and electricity to run the process. 

See Figure 16 for a simplified flow diagram for this section of the process. The combined feeds 

to the combustor have an energy content of 178 MMkcal/hr (706 MMBtu/hr). The lignin residue 

provides the majority (59%) of this energy to the combustor. Combined, the electricity and steam 

produced is 66% of the energy to the combustor. The energy lost to the flue gas is due to its high 

temperature and fairly large amount of volatile material in the vapor phase. Though it would 

seem desirable to reduce this loss by further cooling the flue gas, operational problems could 

arise, such as condensation of acidic liquids or low gas velocities through the stack. 

59 
All heat flows are fractions of the energy content 

of the feed to the COMBUSTOR 

BOILER TURBINE/

GENERATOR

COMBUSTOR

Lignin Residue 59% 

Evaporator Syrup 37% 

Anaerobic Biogas 2% 

Digestor Solids 0.2% 

Flue Gas 31% 

Heat Losses 1% 

68% 

Feed Water 5% 

Blowdown1% 

Electricity 15% 

Condenser 5% 

Steam to Process 

51% Power Losses 

1% 

Humid Fresh Air 1% 

71% 

Figure 16. CFBC/Turbogenerator Energy Balance 

III. Process Economics 

As mentioned earlier, one of the primary purposes for developing a detailed process design, 

simulation model, and cost estimate is to determine the economics of ethanol production. The 

cost of ethanol production is used either to assess its potential in the marketplace with an absolute 

cost of production or to evaluate research proposals by looking at the relative cost of production 

of process modifications that could be developed through research. 

III.1 Analysis Procedure 

The total project investment (based on total equipment cost) as well as variable and fixed 

operating costs, are developed first. With these costs, we use a discounted cash flow analysis to 

determine the production cost of ethanol when the net present value of the project is zero. This 

section describes these three cost areas and the assumptions made to complete the discounted 

cash flow analysis. 

III.1.1 Total Project Investment 

Section II of this report describes the details of the conceptual process design and how the 

purchase cost of all equipment was determined. The next step is to determine the installed cost of 

that equipment. The installation cost can be determined by a detailed study of everything 

required to install the necessary equipment and make it operational. This type of detail is not 

warranted for the current level of the estimate. When the process is much closer to construction 

and an estimate of +/- 5% accuracy is required for financing, more details will be necessary. This 

study is more of a +25%/-10% accuracy, making a “factored” approach satisfactory. Many 

engineering texts such as Garrett6

 or Peters and Timmerhaus63 list installation factors that can be 

applied to purchased equipment costs to determine the installed cost. The ICARUS Process 

Evaluator23 develops a detailed installation cost estimate using its estimate of the piping and 

instrumentation required for each type of equipment. Although the ICARUS estimate is more 

detailed than a simple factored method, it, as well as the standard textbook factored methods, was 

developed for the chemical and petroleum industry, not an aqueous-based biotechnology process. 

Standards for industries handling concentrated chemicals and fuels are based (to a significant 

degree) on the safety aspects of the process. Many of these standards (such as API for refineries 

and ANSI for chemical plants) are unnecessary for an aqueous-based process. A better 

60 
methodology is to use the expertise and engineering practices that Delta-T has developed in the 

design and construction of starch-based ethanol plants. 

Delta-T reviewed the factors for direct installation costs suggested by Chem Systems

64 in its 1994 

study of this process (Chem Systems in turn took these installation factors from Walas65). These 

installation factors, given in Table 25, were applied to the equipment purchase costs. In addition 

to the Chem Systems installation factors, a more recent evaluation performed by Harris.66 

provided equipment specific installation and scaling factors for corn stover feed handling, 

continuous pretreatment reactors, and solid-liquid separation equipment. In general, the Harris 

factors were higher than those from Chem Systems, particularly for smaller equipment like 

pumps. The overall installation “factor” was then calculated as the quotient of the sum of all 

purchased costs and the sum of all installed costs, excluding sections A600 and A800. Delta-T 

compared this ratio (1.42) to several existing corn ethanol projects, where the actual ratio was 

1.46. Therefore, these installation factors were accepted for most equipment except where other 

information, such as installation factors from vendors, was available. Harris obtained installation 

factors for the stover handling and solid-liquid separation equipment; as a result this overall 

installation factor (excluding A600 and A800) is 1.61 for this design case. See Appendix B for a 

complete listing of the equipment, along with its purchased and installed costs. 

Once the installed equipment cost has been determined from the purchased cost and the 

installation factor, it can be indexed to the project year being considered. In this case, we selected 

2000 so as to align with petroleum costs projected by the Energy Information Administration 

(EIA),67 which is in 2000 dollars. The purchase cost of each piece of equipment has a year 

associated with it. It might be 1998, if a vendor quote was obtained in that year, or it might be 

1997 if ICARUS was used as its basis. The purchased cost year will be indexed to the year of 

interest using the Chemical Engineering Index.68 Existing values for the index ranging from 1990 

to 1999 were regressed to a simple equation. The resulting equation is used to extrapolate to 

future years (referred to as “out years”) when such an analysis is desired. Table 26 gives the 

index as a function of date. 

61 
Table 25. Installation Factors69 

Equipment Multiplier*

Agitators – Carbon Steel (CS) 1.3-1.4 

Agitators – Stainless Steel (SS) 1.2-1.3 

Boilers 1.3 

Compressors (motor driven) 1.3 

Cooling Towers 1.2 

Distillation columns – Carbon Steel 3.0 

Distillation columns – Stainless Steel 2.1 

Filters 1.4 

Heat Exchangers (S&T) – Carbon Steel/Stainless Steel 2.1 

Pumps – Lobe 1.2-1.4 

Pumps – Centrifugal, Carbon Steel 2.8 

Pumps – Centrifugal, Stainless Steel 2.0 

Pressure Vessels – Carbon Steel 2.8 

Pressure Vessels – Stainless Steel 1.7 

Tanks – Field Erected, Carbon Steel 1.4 

Tanks – Field Erected, Carbon Steel with Lining 1.6 

Tanks – Field Erected, Stainless Steel 1.2 

Solids Handling Equipment 1.2-1.4 

Turbogenerator 1.5 

*Installed cost = (purchased equipment cost) x (multiplier) 

Table 26. Chemical Engineering Purchased Equipment Index 68 

Year Index Year Index

1990 357.6 1997 386.5 

1991 361.3 1998 389.5 

1992 358.2 1999 390.6 

1993 359.2 2000 394.1 

1994 368.1 

1995 381.1 

1996 381.7 

The total equipment cost in the year of interest has now been determined. To obtain the total 

project investment, we must add several other items. Table 27 summarizes the categories and 

additional factors proposed by Chem Systems

69 based on industry standards. Delta-T reviewed the 

items and factors and determined that they were consistent with other projects the company has 

completed. 

62 
Table 27. Additional Costs for Determining Total Project Investment 69 

Item Description Amount

Warehouse 1.5% of Total 

Installed 

Equipment Cost 

Site 

Development 

Site Development: Includes fencing, curbing, parking, lot, roads, 

well drainage, rail system, soil borings, and general paving. This 

factor allows for minimum site development assuming a clear site, 

with no unusual problems such as right-of-way, difficult land 

clearing, or unusual environmental problems. 

9% of the 

installed cost of 

process equip. 

(areas A100, 

A200, A300, and 

A500). 

Prorateable 

Costs 

This includes fringe benefits, burdens, and insurance of the 

construction contractor. 

10% of Total 

Installed Cost 

Field 

Expenses 

Consumables, small tool equip. rental, field services, temporary 

construction facilities, and field construction supervision. 

10% of Total 

Installed Cost 

Home Office 

and Const. 

Engineering plus incidentals, purchasing, and construction. 25% of Total 

Installed Cost 

Project 

Contingency 

Small because of the detail included in the process design. 3% of Total 

Installed Cost 

Other Costs Start-up and commissioning costs. 

Land, rights-of-way, permits, surveys, and fees. 

Piling, soil compaction/dewatering, unusual foundations. 

Sales, use, and other taxes. 

Freight, insurance in transit and import duties on equipment, 

piping, steel, instrumentation, etc. 

Overtime pay during construction. 

Field insurance. 

Project team. 

Transportation equipment, bulk shipping containers, plant vehicles, 

etc. 

Escalation or inflation of costs over time. 

Interest on construction loan. 

10% of Total 

Capital 

Investment 

Table 28 summarizes the Total Installed Equipment Cost. Table 29 illustrates the application of 

factors in Table 27 to obtain the Total Project Investment (TPI). 

Table 28. Total Installed Equipment Costs 

Process Area Capital Cost 

A100 Feed Handling $7,500,000 

A200 Pretreatment $19,000,000 

Neutralization/Conditioning $7,800,000 

A300 Saccharification/Fermentation $9,400,000 

A500 Distillation and Solids Recovery $21,800,000 

A600 Wastewater Treatment $3,300,000 

A700 Storage $2,000,000 

A800 Boiler/Turbogenerator $38,300,000 

A900 Utilities $4,700,000 

Total Installed Equipment Cost $113,700,000 

Model I0203I, 2000 $ 

63 
Table 29. Total Project Investment (TPI) 

Total Installed Equipment Cost (Table 28) 

Warehouse 

Site Development 

Total Installed Cost 

$113,700,000 

$1,700,000 

$5,900,000 

$121,200,000 

Indirect Costs 

Field Expenses + Prorateable Expenses 

Home Office & Construction Fee 

Project Contingency 

$24,300,000 

$30,300,000 

$3,600,000 

Total Capital Investment $179,400,000 

Other Costs (Startup, Permits, etc.) $17,900,000 

Total Project Investment $197,400,000 

Model: I0203I, 2000 $ 

III.1.2 Variable Operating Costs 

Variable operating costs, which include raw materials, waste handling charges, and by-product 

credits, are incurred only when the process is operating. All raw material quantities used and 

wastes produced were determined using the ASPEN mass and energy balance model. Appendix 

C documents the sources of the costs of these items. Table 30 summarizes these costs, both on a 

per-year and per-gallon of ethanol basis. 

Table 30. Variable Operating Costs (Based on 69.3 MM annual gallons ethanol) 

Raw Material kg/hr Cost ($/lb) MM$/yr Cents/gal 

Ethanol

Biomass Feedstock* 98,039 0.0128 23.17 33.45 

Clarifier Polymer 28 1.2500 0.66 0.95 

Sulfuric Acid 3,288 0.0124 0.76 1.09 

Lime 2,395 0.0348 1.54 2.23 

Corn Steep Liquor 1,306 0.0804 1.95 2.81 

Purchased Cellulase 6,824 0.0552 6.98 10.08 

Diammonium Phosphate 163 0.0706 0.21 0.31 

Propane 20 0.0022 0.0022 0.001 

Make-up Water 186,649 0.0001 0.40 0.58 

BFW Chemicals 1.0 1.3497 0.03 0.04 

Cooling Water Chemicals 1.9 1.0204 0.04 0.05 

WWT Chemicals 57.9 0.1579 0.17 0.24 

WWT Polymer 0.2 2.551 0.01 0.01 

Ash Disposal 4,492 0.0094 0.78 1.13 

Gypsum Disposal 7,217 0.0094 1.25 1.81 

Electricity Credit -18,747 (kW) 0.041/kWh -6.43 -9.29 

*Cost of as-received corn stover, 15% moisture, $30/dry U.S. ton 

Model: I0203I, 2000 $ 

See Appendix C for cost sources 

64 
As with capital equipment, the costs for chemicals are associated with a particular year. To index 

the costs from the year in which they were obtained to the year the analysis is being performed, 

we use the Industrial Inorganic Chemical Index70 from SRI Consulting. Data for this index were 

available for years 1980 through 1999. These data were regressed to a simple equation and used 

to extrapolate to other years, as shown in Table 31. 

Table 31. Inorganic Chemical Index 70 

Year Index Year Index

1982 91.1 1993 96.0 

1983 86.6 1994 91.3 

1984 85.9 1995 93.3 

1985 88.1 1996 94.7 

1986 86.8 1997 98.8 

1987 86.1 1998 92.1 

1988 91.9 1999 96.8 

1989 99.2 2000 98.8 

1990 101.7 

1991 102.5 

1992 100.0 

Note: 1990 to 1999 represents actual data. 

2000 was extrapolated from the data. 

III.1.3 Fixed Operating Costs 

Fixed operating costs are generally incurred fully whether or not the plant is producing at full 

capacity. These costs include labor and various overhead items. Delta-T recommended 

information on fixed operating costs using data from similar ethanol plant projects the company 

has been involved with (ranging up to 230 million L [60 million gal] annual production), as well 

as the standard reference of Peters and Timmerhaus63. Table 32 contains the Delta-T 

recommendation, except for the number of yard employees. Harris determined the number of 

yard employees for the corn stover feed handling system16. 

Salaries do not include benefits; they are covered in the general overhead category. General 

overhead is a factor of 60% applied to the total salaries and covers items such as safety, general 

engineering, general plant maintenance, payroll overhead (including benefits), plant security, 

janitorial and similar services, phone, light, heat, and plant communications. 

Annual maintenance materials, based on the experience of Delta-T and Peters & Timmerhaus, 

were estimated as 2% of the total installed equipment cost (shown in Table 28). Additionally, 

insurance and taxes were estimated at 1.5% of the total installed cost (shown in Table 29) using 

both Delta-T’s in-house information and published information. 

It is important to note that the estimates provided for this section are based on a representative 

Midwest U. S. location. The estimates can vary significantly depending on specific location. 

65 
Table 32. Fixed Operating Costs 

Annual Salary Number of Personnel Total Annual Cost

Plant Manager $80,000 1 $80,000 

Plant Engineer $65,000 1 $65,000 

Maintenance Supervisor $60,000 1 $60,000 

Lab Manager $50,000 1 $50,000 

Shift Supervisor $37,000 5 $185,000 

Lab Technician $25,000 2 $50,000 

Maintenance Technician $28,000 8 $224,000 

Shift Operators $25,000 20 $500,000 

Yard Employees $20,000 32 $640,000 

General Manager $100,000 1 $100,000 

Clerks & Secretaries $20,000 5 $100,000 

Total Salaries (1998 $) $2,054,000 

Total Salaries (2000 $) $2,150,000 

Factor

General Overhead 60% Of Total Salaries $1,293,000 

Maintenance 2% Of Installed Equipment Cost $2,273,000 

Insurance & Taxes 1.5% Of Total Installed Cost $1,819,000 

Model: I0203I, 2000 $ 

The salaries are on a 1998 basis and will need to be indexed to other cost years when appropriate. 

The index to adjust these costs is taken from the Bureau of Labor Statistics71 and is given in Table 

33. The available data were regressed to a simple equation. The resulting regression equation 

can be used to extrapolate to out years. 

Table 33. Labor Index 71 

Year Index Year Index

1980 8.3 1992 14.51 

1981 9.12 1993 14.82 

1982 9.96 1994 15.13 

1983 10.58 1995 15.62 

1984 11.07 1996 16.17 

1985 11.56 1997 16.57 

1986 11.98 1998 17.09 

1987 12.37 1999 17.38 

1988 12.71 2000 17.93 

1989 13.09 

1990 13.54 

1991 14.04 

III.1.4 Discounted Cash Flow Analysis and the Selling Cost of Ethanol 

Once the major three cost areas have been determined—(1) total project investment, (2) variable 

operating costs, and (3) fixed operating costs—a discounted cash flow analysis can be used to 

determine the minimum selling price per gallon of ethanol produced. The discounted cash flow 

analysis program iterates on the selling cost of ethanol until the net present value of the project is 

zero. This analysis requires that the discount rate, depreciation method, income tax rates, plant 

life, and construction start-up duration be specified. The minimum ethanol selling price is the 

66 
selling price of ethanol that makes the net present value of the biomass to ethanol process equal to 

zero with a 10% discounted cash flow rate of return over a 20 year plant life. 

The discount rate for this analysis was set at 10%. This rate was selected based on the 

recommendation by Short et al.72 in his description of how to perform economic evaluations of 

renewable energy technologies for DOE. His view is that “In the absence of statistical data on 

discount rates used by industrial, transportation and commercial investors for investments with 

risks similar to those of conservation and renewable energy investments, it is recommended that 

an after tax discount rate of 10%... be used.” 

For this analysis, we assumed that the plant would be 100% equity financed. This, along with our 

other financial assumptions, is of course subject to change for a specific project. For this analysis 

these parameters were chosen to provide a standard method that was not clouded by the infinite 

possibilities of financing, but are certainly not the final word in project financing. Figure 17 

illustrates the dependence of minimum ethanol selling price on both the percentage of equity 

financing and the after tax discount rate (IRR), based on 7.5% interest on a 10-year loan. 

$0.80 

$0.90 

$1.00 

$1.10 

$1.20 

$1.30 

$1.40 

$1.50 

$1.60 

$1.70 

0% 20% 40% 60% 80% 100% 

Equity (%) 

Minimum Ethanol Selling Price (

$/gal) 

20%IRR 

15%IRR 

10%IRR 

Figure 17. Effect of Varying IRR and Equity on Minimum Ethanol Selling Price 

(Loan Rate=7.5%, Loan Term=10 years) 

To determine the depreciation amount for the calculation of federal taxes to be paid, Short et al.73 

recommends the use of the IRS Modified Accelerated Cost Recovery System (MARCS). Within 

the MARCS system is the General Depreciation System (GDS), which allows both the 200% and 

150% declining balance (DB) methods of depreciation. This offers the shortest recovery period 

and the largest tax deductions. IRS publication 534 (IRS 1993) indicates that steam production 

plants should use a 20-year recovery period. The IRS indicates that other property not 

specifically described in the publication should be depreciated using a 7-year recovery period. 

Short et al.74 indicates that property listed with a recovery period less than 10 years should use the 

200% DB depreciation method and that a 20-year recovery period property should use the 150% 

DB depreciation. 

67 
State taxes are not considered, primarily because the location of the plant has not been determined 

and tax rates vary quite drastically (from 0% to 12%). Short et al72 suggested using the highest 

federal tax bracket, which is 39% for large corporations. 

Return on investment is calculated on a per gallon basis. Income tax is averaged over the plant 

life and that average is calculated on a per gallon basis. The amount of income tax to be paid by a 

potential ethanol producer varies annually due to changes in the volume of product produced and 

the allowable depreciation deduction. In fact, no income tax is paid in the first three years of 

operation because the depreciation deduction is greater than the net income. 

The construction time is important to the cash flow analysis because there is generally no income 

during construction but huge sums of money are being expended. Perry and Green75 indicate that 

small projects (less than $10 million investment) can be constructed in fewer than 18 months and 

that larger projects can take up to 42 months. An overview76 of petroleum refining economics 

indicates that large refineries (of the order of $1.5 billion investment) can be constructed in 24 

months. Certainly this ethanol process is much smaller than the petroleum refinery, so using a 

construction time of more than 24 months is conservative and fits within these references. DeltaT’s experience with grain-to-ethanol plants indicates that it will require a little more than 2 years 

to complete a project of this size. An important difference between this type of facility and a 

refinery are the large number of field-erected vessels in this process. Their on-site construction 

and proximity will cause the construction time to be a little longer. Table 34 summarizes the 

schedule for construction and the cash flow during that time. 

68 
Table 34. Construction Activities and Cash Flow 

Project

Start

Month 

Project

End 

Month 

Activity Description % of Project 

Cost

0 6 Project plan and schedule established, conceptual and 

basic design engineering, permitting completed. Major 

equipment bid packages issued, engineering started on 

selected sub-packages, P&IDs complete, preliminary 

plant and equipment arrangements complete. 

8.00% 

6 18 All detailed engineering including foundations, structure, 

piping, electrical, site, etc. complete; all equipment and 

instrument components purchased and delivered; all site 

grading, drainage, sewers, rail, fire pond, foundation, 

and major structural installation complete; 80% of all 

major process equipment set (all except longest lead 

items), all field fabricated tanks built, and the majority 

of piping and electrical materials procured. 

60.62% 

18 30 Complete process equipment setting, piping, and 

instrumentation installation complete; all electrical 

wiring complete; all building finishing and plumbing 

complete; all landscaping complete; pre-commissioning 

complete; and commissioning, start-up, and initial 

performance test complete. 

31.38% 

TOTAL 100.00% 

Notes: 

1. The above presumes no utility or process equipment orders placed prior to month seven. 

2. Expenditures based on typical 60 MM gal/yr grain-to-ethanol facility. 

Perry and Green75 indicate that for a moderately complex plant start-up should be about 25% of 

the construction time - or 6 months, in this case. Delta-T’s experience with start-up demonstrates 

that a large grain-to-ethanol plant could be started in less time, but a biomass ethanol plant is 

more complex than a grain ethanol plant. Considering that this design is for the “nth” operating 

plant, we assumed a start-up time of 6 months. The start-up period is not completely wasted, 

however. We expect that an average of 50% production could be achieved during that period 

with about 75% expenditure of variable expenses and 100% of fixed expenses. 

Peters and Timmerhaus63 define working capital as money available to cover (1) raw materials 

and supplies in inventory 2) finished product in storage, (3) accounts receivable, (4) cash on hand 

for monthly payments such as wages and maintenance supplies, (5) accounts payable, and (6) 

taxes payable. They indicate that working capital is usually 10%-20% of the total capital 

investment. This flow of money is required over the life of the plant, beginning in the start-up 

phase to make product that generates revenue to use in purchasing more materials and supplies. 

For this project, 10% would be about $18 million. On-site ethanol storage capacity is seven days; 

assuming the product can be made, shipped and payment received in 30 days is conservative. 

One month’s raw materials, labor, maintenance, taxes and overhead is $4 million. Therefore, a 

lower number seems reasonable. Garrett

6

 suggests that using a fraction of the yearly operating 

cost, typically 10-35% is more relevant. Using these percentages results in a working capital 

range of $5 to $16 million. We chose to use $10 million, or 5% of the total capital investment. 

69 
Table 35 summarizes the parameters used in the discounted cash flow analysis. 

Table 35. Discounted Cash Flow Parameters 

Plant Life 20 years 

Discount Rate 10% 

General Plant Depreciation 200% DB 

General Plant Recovery Period 7 years 

Steam Plant Depreciation 150% DB 

Steam Plant Recovery Period 20 years 

Federal Tax Rate 39% 

Financing 100% equity 

Construction Period 

1st 6 Months Expenditures 

Next 12 Months Expenditures 

Last 12 Months Expenditures 

2.5 years 

8% 

61% 

31% 

Working Capital 5% of Total Capital Investment 

Start-Up Time 

Revenues 

Variable Costs 

Fixed Costs 

6 months 

50% 

75% 

100% 

Using the discounted cash flow parameters in Table 35, plus the cost information in Table 29, 30 

and 32, the resulting minimum ethanol selling price of pure ethanol is $1.07/gal (see Table 36). 

Using the total project investment estimate margin of +25%/-10%, the impact on the cost of 

ethanol would be a low of $1.02/gal and a high of $1.19/gal. Samples of the discounted cash 

flow, operating costs, and summary worksheets are in Appendix D. 

Table 36. Summary of Yields, Rates, and Conversion Costs 

Feedstock Rate (dry metric tons/day) 2,000 

Ethanol Yield (gal/dry US ton feedstock) 89.7 

Ethanol Production (MM gal/yr) 69.3 

Total Equipment Cost (MM $) 113.7 

Total Project Investment (capital) (MM $) 197.4 

Non-feedstock Raw Materials (MM $/yr) 12.7 

Waste Disposal (MM $/yr) 2.0 

Fixed Costs (MM $/yr) 7.5 

Excess Electricity Generated (kWh/gal ethanol) 2.28 

On-Line Time (hr/yr) 8,406 

Minimum Ethanol Selling Price $1.07 /gal (+$0.12/-$0.05) 

Model: I0203I, 2000 $ 

The $1.07/gal can be further broken down into the cost of each process area. Figure 18 illustrates 

the contribution to the overall cost by process area and capital, operations, and fixed costs. 

70 
Storage 

Utilities 

Boiler/Turbogenerator 

Wastewater Treatment 

Distillation and Solids 

Recovery 

Cellulase 

Saccharification 

& Fermentation 

Pretreatment / 

Conditioning 

Feed Handling 

Biomass 

-20% -10% 0% 10% 20% 30% 40% 

Raw Materials Process Electricity 

Fixed Costs 

31% 

5% 

19% 

8% 

9% 

12% 

2% 

8% (Net) 

4% 

1% $1.07/gallon +$0.12/-$0.05 

Capital Recovery Charge 

Grid Electricity Total Plant Electricity 

Figure 18. Cost Contribution Details from Each Process Area (% of Ethanol Selling Price) 

These costs are probably still too high for a company to start constructing a grass-roots plant 

based on undemonstrated technology. Plants that are being engineered today have some niche 

that allows them a special advantage in the short term for a small market segment. This could be 

feedstock costs (very low or negative for environmental wastes), used equipment (making use of 

related equipment that has been shut down), co-location with existing facilities (biomass 

combustors and waste treatment facilities), or a combination of these. It is not expected that grass 

roots, large-scale cellulosic biomass-to-ethanol plants will be built until after these first pioneer 

plants. 

III.1.5 The Cost of Sugar 

Sugars are an intermediate product in the formation of ethanol. Hemicellulose is hydrolyzed to 

form xylose, arabinose, galactose, and mannose in the pretreatment area. Cellulase enzyme 

saccharifies the cellulose into glucose. For this analysis enzymatic hydrolysis is assumed to be 

operated in a near sterile way and nearly to completion so that a transferable sugar stream is 

produced as product. 

To analyze the cost of the intermediate sugar stream the following areas were removed from the 

biomass-to-ethanol process model and economics: wastewater treatment (a cost was kept for 

treatment of the pretreatment flash vapor), fermentation, distillation and stillage treatment, and 

storage. Also, a counter-current washer was added after the saccharification area to separate 

lignin for combustion from the dilute mixed sugar stream. Mass balances and capital and 

operating costs were determined for the sugar process and the minimum sugar transfer price was 

calculated to be 6.4¢/lb. Table 37 shows the sugar stream composition. As in the design case for 

71 
ethanol, all of the hydrolysis (90% of theoretical) is assumed to occur in the saccharification 

tanks. In reality, glucose levels in the saccharification step may limit the extent of hydrolysis. 

Table 37. Mixed Sugar Stream Concentration From Saccharification 

Sugar Concentration (g/L) 

Glucose 65 

Xylose 38 

Arabinose 5.2 

Mannose 2.7 

Galactose 3.4 

Total 114.3 

Model: R0204E 

In some cases the lignin stream can be sold either to a nearby plant that converts lignin into 

higher value byproducts or a larger more cost-efficient biomass power facility. Selling the lignin 

at the same price as the feedstock (on a lower heating value basis) reduces the sugar price to 

5.6¢/lb. 

IV. Sensitivity Analysis 

The cost of ethanol as determined in the previous section was derived using technology that has 

been developed or is currently being developed. The process targets in the design represent what 

must be achieved to obtain the $1.07 per gallon reported. When any target is not met, the cost is 

affected to varying degrees. In addition, uncertainty about equipment design and installation and 

construction costs will impact the economics. Some process targets can be met through research 

of the core technologies: feedstock collection, pretreatment, saccharification (enzyme 

development) and fermentation (ethanologen development). Others, like feedstock composition 

variability are not as controllable. The key is to understand the impact of those types of 

parameters that are likely to vary, and how they might be controlled to a definable range. For 

example, corn stover may need to be stored covered, or be used within a certain window after 

harvesting to avoid carbohydrate degradation. Equipment and operating costs are another area 

that research is less able to affect, since demand will affect the price of the ingredient or 

equipment. Discussed here are process targets that have been identified as key ones to understand 

and achieve. In most cases, values used for the sensitivities are picked from current experimental 

data, to demonstrate the effect of technology advancement (or lack of) on the economic viability 

of the process. 

IV.1 Stover Composition, Cost, and Handling 

Different parts of the corn have different compositions. The relative proportions of the various 

anatomical parts present in a given lot of feedstock will be affected by the genetics of the corn, 

environmental factors, harvest, and storage practices. These variations can have a significant 

effect on cost through yield alone, and preliminary observations suggest that variation in the 

solids composition of anatomical fractions of a plant can have an effect on pretreatment 

efficiency13. 

Improved harvesting methods, weather, and demand are some of the factors that will affect the 

stover cost. The results of a small stover collection program in 1997-1998 by Iron Horse Custom 

Farming of Harlan, Iowa, reported stover collection costs between $31-$36 per dry U.S. ton9

. 

Studies by contractors for DOE have reported a range of $35-$46 per dry U.S. ton with current 

72 
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collection methods77. ORNL has reported that almost all of the collectable stover becomes 

available for $55 per dry U.S. ton11. If these prices remain the norm due to any of the factors 

mentioned above, then the production cost of ethanol could be as high as $1.35/gal using stover 

purchased at $55 per dry U.S. ton. 

Bale handling in the plant is currently envisioned to require a large complement of yard workers 

to move the bales from the trucks to storage or the feedstock handling area. Harris estimated 4 

laborers per shift. If the number can be reduced from 32 to 8 (2 per shift) the resulting cost 

savings is $0.02/gal. Such a reduction might occur from improved handling equipment or 

practices. 

IV.2 Pretreatment Yields and Cost 

Conversion of the hemicellulosic portion of the stover is important when it contains almost half 

(44%) of the available sugars. Xylan makes up 72% of the hemicellulosic sugars. Table 38 

shows the effect of pretreatment yield on overall yield and ethanol selling price. If no more 

improvement is made in yields than the current data25 shows, then there is a $0.11/gal increase in 

the ethanol selling price. 

Table 38. Effect of Pretreatment Yields on Minimum Ethanol Selling Price 

Pretreatment

Hemicellulose to

Monomer Yield 

Overall 

Ethanol

Yield

(gal/dry U.S. 

ton)

Change in 

Overall 

Yield (%) 

Ethanol

Selling Price 

($/gal) 

Change in price 

from design case 

($/gal) 

67.5% 80.4 -10 $1.18 +$0.11 

80% 85.5 -5 $1.12 +$0.05 

90% 89.7 $1.07 

95% 91.6 +2 $1.05 -$0.02 

While the equipment designed for continuous dilute acid pretreatment of the stover is similar to 

hydrolyzers used in the pulp and paper and rendering industries, the solids handling for stover 

may be significantly different, causing a more expensive reactor. Conditions in the reactor may 

require more exotic metallurgy than Inconel. These are not first of a kind costs, but a more 

expensive reactor design overall. If the costs are 50% higher (or lower) than currently envisioned 

(about $17MM installed equipment cost), the ethanol selling price will change by $0.04/gal. 

IV. 3 Gypsum 

Solid-liquid separation prior to overliming and neutralization allows gypsum to be removed from 

the process and prevents deposits in the high temperature product recovery equipment. If this 

step is removed, there is a savings of $0.03/gal due primarily to capital reduction (-$7.2MM in 

conditioning/neutralization, +2.1MM in saccharification/fermentation and distillation) and a 

slight yield increase (0.4 gal/ton) from sugars that exited with the gypsum waste stream. These 

effects are easy to quantify. The impact of having the gypsum in the process is more difficult to 

translate to cost. Without the separation, gypsum in the saccharification feed stream (306) goes 

from 28 kg/hr (0.1%) to 5,100 kg/hr (1%). It is 0.06% of the solids with the separation and 

becomes 10% of the solids if the separation is removed. About this same concentration goes to 

the stripper column and the first evaporator effect; high solids recovery in the solids recovery 

separation step keeps most of the gypsum out of the second and third effects. The gypsum ends 

73 
up in the combustor, lowering the feed’s lower heating value 15% (4,179 to 3,552 Btu/lb). The 

gypsum will affect the SOx production in the combustor, but whether positively due to the 

calcium, negatively due to the sulfur, or some combination of both is unknown at this time. The 

unreacted portion will go with the ash to waste disposal. 

IV.4 Saccharification and Fermentation Yields and Costs 

If the enzyme cost is higher or lower than estimated in this analysis, it will have a direct effect on 

the ethanol selling price. Since the cellulase subcontracts are in the second year, it is early to 

have a preparation to test for efficacy and determine loading. There are several possible tradeoffs to minimize the overall effect of a higher than expected enzyme cost per ethanol gallon. One 

of them is residence time. Doubling the residence time in the saccharification tanks (from 1.5 

days) will increase the TPI by $4.4MM and the ethanol selling price by $0.01/gal. For every 5 

FPU/ g cellulose increase in loading, the ethanol selling price increases $0.04/gal, so for the cost 

of doubling the residence time, only a minimal increase in loading can be achieved. 

If increasing the residence time can minimize the enzyme loading, the overall MESP can be 

minimized using a sensitivity analysis with empirical data. An example of that sensitivity 

analysis was run on an unoptimized corn stover pretreatment (P010129CS). That pretreatment 

was run at 165°C for 8 min. with an acid concentration of 1.37% and is described in a paper by 

Schell78. The enzymatic digestibilities of the resulting hydrolyzed solids were measured in an 

SSF using Iogen (Ottawa, Canada) cellulase enzyme (lot no. BRC 191095) and a Saccharomyces 

cerevisiae D5A in shake flasks. The flasks were loaded with 5.65% cellulose (equivalent to 

approximately 17% total solids). Since the enzyme is not representative of what will be produced 

by the DOE/enzyme manufacturer partnerships, the pretreatment conditions were not optimized, 

and the enzymatic digestibility measurements do not match process conditions (e.g., 

saccharification without fermentation vs. SSF with only glucose fermented) this study is only an 

example. It is not intended to show the ideal enzyme loading/residence time combination but 

rather to show how that optimization could be determined. 

Yields from the SSF were calculated by dividing the final ethanol concentration by the theoretical 

ethanol concentration from cellulose after subtracting out ethanol added with the inoculum. The 

resulting yield is probably a conservative estimate of cellulose conversion because it does not 

include other fermentation products; however, it is close to what can be achieved in the process. 

Figure 19 shows ethanol yields for five enzyme loadings (5, 10, 15, 20, and 25 FPU/g cellulose) 

at multiple SSF times (ranging from 7 hours to 168 hours). Since only SSF data are available, for 

modeling purposes we assumed that the sacccharification and fermentation times are each half of 

the SSF time. In the design case, the enzyme loading is 12 FPU/g cellulose, the saccharification 

time is 36 hours, the fermentation time is 36 hours (the equivalent SSF time is 72 hours), and the 

cellulose hydrolysis yield is 90%. Those parameters are discussed in section II.3.4 and were 

achieved using a more optimum pretreatment than was used for this study; therefore, the design 

case has better results than those shown in Figure 19. 

74 
100 

90 

80 

70 

60 

50 

40 

30 

20 

10 

5 

10 

15 

20 

25 Loading 

(FPU/g) 

0 

0 20 40 60 80 100 120 140 160 

Time (Hours) 

Figure 19. SSF Yields for Multiple Enzyme Loadings 

Each of the enzyme loading, residence time, and yield combinations shown in Figure 19 were 

entered into the process model, and the model was run to calculate the corresponding MESPs. 

Those MESPs are shown in Figures 20 and 21. Figure 20 portrays the MESP at each time point 

with each of the enzyme loadings. It shows that the residence time should be at or above 144 

hours and that the effect of increasing residence time is large until it reaches about 120 hours. 

Figure 21 portrays the MESP at each enzyme loading with each time point. It shows that the 

optimum enzyme loading is about 10 FPU/g cellulose. Both figures show the decreasing effect 

additional fermentation time (as additional fermentation capacity) has on the ethanol selling price. 

These results are highly dependent upon the corn stover, pretreatment conditions, enzyme 

cocktail, saccharification/fermentation design, and enzyme cost so the optimums will probably 

change if any of those process options are different. Yield (%) 

75 

180 
MESP ($/gal) MESP ($/gal) $1.60 

$1.50 

$1.40 

$1.30 

$1.20 

$1.10 

$1.00 

$1.60 

$1.50 

$1.40 

$1.30 

$1.20 

$1.10 

$1.00 

5 

10 

15 

20 

25 

Loading 

(FPU/g) 

0 20 40 60 80 100 120 140 160 180 

Time (Hours) 

Figure 20. MESPs for Multiple Enzyme Loadings 

120 

144 

168 

Residence 

Time 

(hours) 

0 5 10 15 20 25 30 

Loading (FPU/g cellulose) 

Figure 21. MESPs for Multiple Residence Times 

Hemicellulase activity in the enzyme preparation may also reduce costs by allowing for a milder 

pretreatment. Again, the work is at an early stage, but some of the commercial preparations show 

76 
hemicellulase activity. NREL is investigating opportunities in hemicellulase and other 

“accessory” enzymes. 

Finding or engineering an organism to ferment hemicellulosic sugars is key to economic yields 

from stover. If an organism is developed, it may metabolize xylose and the minor sugars slower 

than, or after, glucose. If the minor sugars (arabinose, mannose, galactose) are not converted, 

there is a $0.09/gal increase ($0.04, $0.03, $0.02/gal, respectively) in the ethanol selling price. 

Table 39 shows other yield effects from a less than robust multi-fermentation organism(s). 

Increasing the residence time to 3 days has the same minimal effect on the ethanol selling price as 

increasing saccharification time, $0.01/gal, so using it to increase ethanol yield can offset 

organism efficiency. 

IV.5 Energy Production 

Solids combustion (coal) is well known. Biomass co-firing has become industry practice among 

power generators to reduce emissions, and biomass power generation has been in California for 

several years. Aside from biomass, pulverized coal and coal slurries are the fuels most similar to 

the lignin residue from the ethanol process. A circulating fluidized bed combustor has been 

identified as the most likely combustor for this feed without drying it. If a CFBC requires 

additional drying or feed handling equipment for the residue, the cost may increase. Conversely, 

a cheaper type of combustor, like a modified pile or grate burner may be adequate. If the 

combustor costs (currently $20.6MM installed equipment cost) change by 50%, the ethanol price 

is affected by $0.05/gal. A 30% change translates to a $0.03/gal effect. 

A $0.041/kWh credit is assumed for excess electricity produced by the plant and sold “to the 

grid”, which is usually an avoided use credit. If the value of the electricity were only 

$0.02/kWh79, the ethanol selling price would be $1.12/gallon; if the value were $0.06/kWh, the 

ethanol selling price would be $1.02/gallon. The value of power is highly regional and fluctuates 

almost by the hour. There is the uncertainty of the plant’s ability to meet contracts or get a good 

price by supplying more at peak demand. A worst case scenario would be no revenue for the 

excess power, implying that the excess steam would be vented or used for some other nonrevenue producing work. There may be some cost benefit in using the excess steam to heat the 

plant buildings. No net revenue for electricity means $0.09/gal increase. Assuming the plant 

could purchase electricity for $0.04/kW makes the ethanol selling price $1.16/gal (with the 

turbogenerator removed from the design), which again hinges on the electricity cost variations. 

Given these two choices, in-house electricity production makes sense as a way to keep the costs 

controlled unless capital costs are controlling the decision. 

If there were a value for the lignin residue outside of the plant, purchasing electricity and 

producing steam with a gas boiler would also reduce the capital costs. 

77 
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Table 39 summarizes the sensitivity results by their cost impact. 

Table 39. Summary of Sensitivity Results by Cost Impact 

Design Parameter Values Overall 

Yield

(gal/dry 

U.S. ton)

Change 

in

Overall 

Yield

(%) 

Ethanol

Selling 

Price

($/gal) 

Change in 

price from

design 

case 

($/gal) Design Case Sensitivity 

Xylose/minor sugar 

fermentation yields 85%/85% 50%/0% 72.0 -20 $1.31 +$0.24 

Stover cost 

$30/dry U.S. ton 

$50/dry U.S. 

ton 89.7 $1.29 +$0.22 

Hemicellulose sugar 

fermentation yields 85% 50% 77.4 -14 $1.22 +$0.15 

Minor sugar (arabinose, 

mannose, galactose) 

fermentation yields 85% 0% 81.1 -10 $1.17 +$0.10 

Pretreatment yield 90% 67.5% 80.4 -10 $1.18 +$0.11 

Electricity credit $0.041 kWh 0 $1.16 +$0.09 

$0.02/kWh 89.7 $1.12 +$0.05 

$0.06/kWh 89.7 $1.02 -$0.05 

Electricity source Produced Purchased $1.16 +$0.09 

Pretreatment yield 90% 80% 85.7 -4 $1.12 +$0.05 

Enzyme loading 12 FPU/g 

cellulose 

17 FPU/g 

cellulose 

89.7 $1.12 +$0.05 

Glucose yield 95% 85% 84.4 -6 $1.12 +$0.05 

Combustor cost $20.6MM +50% $1.12 +$0.05 

Pretreatment reactor cost $17MM +50% $1.11 +$0.04 

Glucose yield 95% 90% 87.0 -3 $1.10 +$0.03 

Saccharification or 

fermentation residence 

time 

1.5 days 3 days 89.7 $1.08 +$0.01 

Pretreatment yield 90% 95% 91.6 +2 $1.05 -$0.02 

Stover handling labor 8/shift 2/shift 89.7 $1.05 -$0.02 

Combustor cost $20.6MM -30% $1.04 -$0.03 

Solid-liquid separation 

before overliming 

Yes No 90.1 +0.5 $1.04 -$0.03 

Pretreatment reactor cost $17MM -50% $1.03 -$0.04 

IV.6 Monte Carlo Analysis 

IV.6.1 Overview 

Monte Carlo analysis is a probabilistic analysis method that couples results with the uncertainty 

of values entered into a model. The basic uncertainty of parameter values can be represented 

with random distribution functions and the results can be shown as probability curves. 

Since all parameter values have some uncertainty, reporting a single result set is an 

oversimplification of the potential results. The single result set is valid for the input set of data if 

78 
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all values are absolutely accurate; however, a probability curve better represents real results based 

on uncertainty of the input parameters. The Monte Carlo analytical method allows the user to 

select one or more input parameters and define the probability curve of values for those 

parameters. It then utilizes random selection (according to the probability assigned) to set a value 

for each parameter, calculates the result, records the results, and repeats the process of selection, 

calculation, and recording numerous times. The final results can be reported in several different 

types of curves; the most common are histograms and probability curves. 

The primary use of Monte Carlo simulation has been for financial decisions, although a few 

groups have begun to use it in the scientific arena. As early as 1986, NREL staff proposed 

utilization of Monte Carlo analysis as a management technique for biomass-to-ethanol research80. 

They used cumulative probability curves to compare potential processes and focused on their 

overlaps and MESP with 50% probability. Akerberg and Zacchi show a probability curve of the 

production cost of lactic acid from starch81 to emphasize that a single production cost is 

insufficient. 

As a preliminary Monte Carlo analysis for this process model, we selected several economic 

parameters, defined their probability curves, and calculated the resulting probability curves for 

ethanol selling price and total project investment. Utilizing Crystal Ball82 as an add-in to Excel83 

simplified the task of curve definition and recording and reporting of results. Process 

performance parameters were not varied during this analysis because of the difficulty of running 

an ASPEN simulation for each iteration. We plan to develop a method for Monte Carlo analysis 

of process parameters so that we can link economic results to research uncertainty as well as 

economic uncertainty. 

IV.6.2 Parameter Estimates 

Probability curves were defined for the following 5 parameters: stover cost, value of excess 

electricity, enzyme price, pretreatment reactor purchase price, and project contingency. Three of 

the parameters (stover cost, value of excess electricity, and enzyme price) affect operating costs 

directly. The other two (pretreatment reactor purchase price and project contingency) affect the 

capital investment and fixed operating costs that are scaled off of capital investment. Table 40 

shows the distributions of the five parameters. 

Table 40. Input Parameter Distribution for Monte Carlo Analysis 

Stover cost Value of

Excess 

Electricity 

Enzyme

Price 

Pretreatment

Reactor

Purchase

Price 

Project

Contingency 

Distribution 

Function 

Triangular Normal Triangular Lognormal Triangular 

Most 

Probable* 

$30/dry US ton $0.04/kWh $0.10/gal 

ethanol 

$2,457,000 3% 

Standard 

Deviation 

$0.008/kWh $500,000 

Minimum $25/dry US ton $0.02/kWh $0.07/gal 

ethanol 

$0 2% 

Maximum $50/dry US ton Infinite $0.20/gal 

ethanol 

Infinite 25% 

* Mean for normal and lognormal distributions 

79 
In all cases, the most probable input is the value in the standard model and has been reported in 

previous sections. 

Two thousand iterations were run using the above probability distributions. For each iteration, all 

5 parameters were randomly varied according to the defined distribution for each value and 

results were calculated and recorded. 

IV.6.3 Results 

The minimum ethanol selling price, total project investment, and Lang factor results were 

recorded. All results are based only upon the minimal number of varied values shown above. 

Obviously, a better analysis can be done once process performance parameters can be 

investigated in addition to the economic parameters that are currently being reported. 

Figure 22 is a histogram of the minimum ethanol selling price and shows that the 90% confidence 

interval of the MESP is $1.06/gal to $1.29/gal. Figure 23 is the probability curve of the MESP 

and shows that the MESP has a 7% probability of being $1.07/gal or less and that it has a 50% 

probability of being $1.17/gal or less. 

2,000 Trials 

Forecast: MESP

2,000 Trials Frequency Chart 8 Outliers

.016 32 

.012 24 

.008 16 

.004 8 

.000 0 1.36 

1.36 

1.00 1.09 1.18 1.27 1.36 

Certainty is 90.00% from 1.06 to 1.29 

Figure 22. Histogram of the Minimum Ethanol Selling Price 

80 
Forecast: MESP 2,000 Trials 

2,000 Trials Cumulative Chart 8 Outliers 

1.000 2000 

.750 

.500 1000 

.250 500 

.000 0 

1.00 1.09 1.18 1.27 1.36 

Figure 23. Probability Curve of the Minimum Ethanol Selling Price 

Figure 24 is a histogram for the total project investment and shows that the 90% confidence 

interval for the TPI is $192,000,000 to $223,000,000. 

Forecast: TPI 

2,000 Trials Frequency Chart 17 Outliers 

.025 49 

.018 36.75 

.012 24.5 

.006 12.25 

.000 0 

184,000,000 196,000,000 208,000,000 220,000,000 232,000,000 

Certainty is 90.10% from 192,000,000 to 223,000,000 

Figure 24. Histogram of the Total Project Investment 

81 
V. Planned Improvements and Extensions to the Model 

The process design and economic model that we have described here is not a static tool. Not only 

will the information contained in the model will be continually improved, but the scope of 

technologies and the capabilities for calculation will also be expanded. The following gives a 

brief overview of the work currently underway or planned. 

V.1 Water Balance and Optimization 

Efficient water usage in a process can reduce the overall costs significantly. Alternate treatment 

schemes can reduce wastewater treatment costs, such as a fractionated approach where waste 

streams are treated differently by type. These may prove more efficient than the current system. 

Water recycle to the process will also be evaluated to determine the optimal approach to using the 

varying degrees of treated water available. 

V.2 Fermentation pH Control 

Biologically catalyzed processes can have a very narrow band of optimum operating conditions. 

The metabolic pathways of an organism are dependent on temperature, pH, inhibitors, and many 

other parameters. Two of the by-products of ethanol fermentation, acetic acid and lactic acid, 

cause a lowering of pH. In addition, some contaminant microorganisms may produce additional 

organic acids. Current process models do not address neutralizing the acids made during 

fermentation to ensure the optimum pH is maintained. 

V.3 Air Emissions 

There are several areas where air emissions are a concern. VOCs, and ethanol are produced 

during fermentation. Adequate treatment of these gases in the existing scrubber and by other 

means needs to be assured. Combustion of lignin residue generates SOx, NOx, and particulates. 

The mechanisms and amounts of these gases generated should dictate whether alternative or 

improved treatment is necessary. For example, emissions that exceed EPA limits for a biomassto-ethanol plant will require further attention. 

V.4 Greenhouse Gas Emissions 

Carbon dioxide is a by-product of fermentation. Combustion of the lignin residue produces N2O, 

CO and CO2 that are considered greenhouse gases. Greenhouse gas emissions from the 

bioethanol facility are comprised of carbon dioxide (CO2), nitrous oxide (N2O) and methane 

(CH4). There are many other compounds that have some potential for causing global warming, 

but these three are the most potent. CO2 is the dominant greenhouse gas in emitted by the plant. 

It is generated as a result of lignin residue combustion in the boiler and as a byproduct of the 

fermentation of glucose to ethanol in the fermentors. Because CO2 is by far the largest 

contributor to climate change effects, it is used as the standard for rating the relative global 

warming potential of other greenhouse gases. In other words, CO2 is assumed to have a global 

warming potential (GWP) of 1. While N2O emissions are much lower globally (and in this plant), 

they have a very high GWP. One gram of N2O is equivalent to 360 grams of CO2. Methane is 

also a potent greenhouse gas. One gram of methane is equivalent to 24 grams of CO2. NOx and 

other air pollutants can effect climate change, but their impacts are small relative to the GWP of 

CO2. 

82 
V.5 Lignin Gasification and Gas Turbine Power Generation 

Another alternative to simply burning the lignin to generate steam and power is to gasify the 

lignin and use a gas turbine to generate power in combination with a steam turbine. This 

technology, termed integrated gasification combined cycle (IGCC) power generation, is currently 

being pursued by the DOE Biomass Power Program for use on biomass feedstocks. The current 

base case will be modified to incorporate this technology so that a comparison can be made 

between it and conventional lignin combustion. 

V.6 Physical Properties of Corn Stover 

As NREL works more with corn stover, we expect our knowledge base of its composition and 

properties to expand. This information will be incorporated into the mass and energy balance 

models to improve its predictive capabilities and provide a better picture of the energy balance of 

the process. 

References and Notes 

1

 Wooley, R., M. Ruth, J. Sheehan, K. Ibsen, “Lignocellulosic Biomass to Ethanol Process 

Design and Economics Utilizing Co-Current Dilute Acid Prehydrolysis and Enzymatic 

Hydrolysis Current and Futuristic Scenarios,” NREL report TP-580-26157, July 1999. 

http://www.ott.doe.gov/biofuels/process_engineering.html 

2 “Wastewater Treatment Options for the Biomass-To-Ethanol Process,” NREL Subcontract 

AXE-8-18020-01, Merrick & Company, Aurora, CO, February 24, 1998. 

http://www.ott.doe.gov/biofuels/process_engineering.html 

3 “Steam and Electricity Generation Options For the Biomass-To-Ethanol Process,” NREL 

Subcontract ACO-8-18019-01, Reaction Engineering International, Salt Lake City, UT, March 

16, 1998. http://www.ott.doe.gov/biofuels/process_engineering.html 

4 ASPEN PlusTM, Release 10.2, Aspen Technology, Inc., Cambridge, MA, February 2000. 

5 Wooley, R.J. and V. Putsche, “Development of an ASPEN PLUS Physical Property Database 

for Biofuels Components,” NREL, Golden, CO, Report MP-425-20685, April 1996. 

http://www.afdc.doe.gov/pdfs/3955.pdf 

6

 Garrett, D.E., Chemical Engineering Economics, Van Nostrand Reinhold, New York, 1989. 

7

 Riley, C. and D. Schell. Technical and Economic Analysis of an Enzymatic Hydrolysis Based 

Ethanol Plant. Solar Energy Research Institute Internal Report. Golden, CO, 1991. 

8

 Sheehan, J. et al. Is ethanol from corn stover a sustainable fuel? A Case Study in Cyber 

Farming. National Renewable Energy Laboratory, Golden, CO. In Press. 

9

 Glassner, D., J. Hettenhaus, T. Schechinger, “Corn Stover Collection Project,” in BioEnergy 

’98—Expanding Bioenergy Partnerships: Proceedings, Volume 2, Madison, WI, pp 1100-1110, 

1998. http://www.afdc.doe.gov/pdfs/5149.pdf. 

10 Ruth, M., “Large Scale Ethanol Facilities and Short Cut for Changing Facility Size,” Internal 

Report, National Renewable Energy Laboratory Technical Memo, October 1999. 

11 Walsh, M.E., et al, ”Biomass Feedstock Availability in the United States: 1999 State Level 

Analysis”, Bioenergy Information Network, Bioenergy Feedstock Development Program, Oak 

Ridge National Laboratory, January 2000. http://bioenergy.ornl.gov/resourcedata/ 

83 
12 Two separate batches of corn stover were received from B/MAP in May and November 2001. 

Sample analysis from totes 10,7,11 and 6 were used from the May batch. Sample analysis for 

Sunds runs P011211CS and B/MAP sample 112901CS were used from the November batch. 

13 Thomas, S. et al, “Estimating the Effects of Compositional Variation on Biomass Conversion 

Process economics,” Internal Report, National Renewable Energy Laboratory C milestone 

report to DOE, October 2001. 

14 Templeton, D.; Hames, B.; Ruth, M.; Wiselogel, A.; McMillan, J. “Determine Compositional 

Stability of Corn Stover during Outdoor Storage: Year One Results,” NREL milestone report 

to DOE, April 2000. 

15 Templeton, D., B. Hames, J. McMillan, “Compositional and Storage Stability Study: Year 2 

Results,” Internal Report, National Renewable Energy Laboratory P milestone report to DOE, 

July 2001. 

16 “Baled Feedstock Handling System,” report no. 99-10600/13, NREL Subcontract ACO-9-

29067-01, Harris Group Inc., Seattle, WA, October 11, 2001. 

http://www.ott.doe.gov/biofuels/process_engineering.html 

17 “Continuous Acid Hydrolysis Reactor,” report no. 99-10600/17, NREL Subcontract ACO-9-

29067-01, Harris Group Inc., Seattle, WA, January 22, 2001. 

http://www.ott.doe.gov/biofuels/process_engineering.html 

18 Hayden, J.G., and J.P. O’Connell, “A Generalized Method for Predicting Second Virial 

Coefficients,” IEC Process. Des. Dev., 14(3), 209, 1975. 

19 “Liquid/Solid Separation’” report no. 99-10600/14, NREL Subcontract ACO-9-29067-01, 

Harris Group Inc., Seattle, WA, March 6, 2001. 

20 Ranatunga, T.D., J. Jervis, R.F. Helm, J.D. McMillan, and C. Hatzis. “Identification of 

Inhibitory Components Toxic Toward Zymomonas mobilis CP4(pZB5) Xylose Fermentation,” 

Appl. Biochem. Biotechnol. 67: 185-198, 1997 defines the hold time to be 30 minutes. The 

time is increased to 1 hr in the model to allow for reduced heating rates and different reaction 

kinetics in a large continuous stirred-tank reactor (CSTR). 

21 H. Majdeski, Delta-T, Williamsburg, VA, personal experience in the flue gas desulfurization 

industry, 1998. 

22 Letter to B. Bunner, Delta-T Corporation, Williamsburg, VA, from A. Bowser, KomlineSanderson Limited, Peapack, NJ, August 1998. 

23 ICARUS Process Evaluator, Version 4.0, ICARUS Corporation, Rockville, MD, June 30, 1997. 

24Jechura, J. “Correlation of Metal Corrosion Data,” Internal Report, National Renewable Energy 

Laboratory Technical Memo, March 2001. 

25Near-term Ethanol prehydrolysis run in NREL’s Sunds reactor. Run #P001207CS Carbon 

Balance Point 2. Limited discussion of this run in “Preliminary Investigation of Corn Stover 

Pretreatment Using Dilute Sulfuric Acid” by D. Schell, Internal Report, National Renewable 

Energy Laboratory, July 2001. 

26Nguyen, Q., “Summary of Corn Stover Pretreatment using the 4-L Steam Gun,” run number 

CS000914-02, Internal Report, National Renewable Energy Laboratory Technical Memo, 

March 2002. 

27 The Sunds reactor in the PDU has been run at approximately 30% solids in several recent runs, 

most recently in March 2002, run number P020311CS #5. Compositional analysis of pretreated 

84 
material from these runs suggests that some of the lignin is being solublized; although rigorous 

mass balances to determine the lignin fate have not been completed to date. 

28 Leonard, R.H. and G.J. Hainy, Industrial and Engineering Chemistry, vol. 37 no. 4, pp. 390-

395, 1945. 

29 Ranatunga, T.D., J. Jervis, R.F. Helm, J.D. McMillan, and R.J. Wooley, “The overliming of 

dilute acid pretreated lignocellulosics, Part 1. The fate of inorganics, uronic acids and ether 

soluble organics,” submitted to Enzyme and Microbial Technology, 1999. 

30 Walker, L.P. and D.B. Wilson, “Enzymatic Hydrolysis of Cellulose: An Overview,” 

Bioresource Technology 36:3-14, 1991. 

31 Zhang, M., C. Eddy, K. Deanda, M. Finkelstein, and S. Picataggio, “Metabolic Engineering of 

a Pentose Metabolism Pathway in Zymomonas mobilis,” Science, 267:240-243, 1995. 

32Kadam, K., “Evaluation of Potential Strains for Corn stover to Ethanol Conversion,” Internal 

Report, National Renewable Energy Laboratory Technical Memo, December 2001. Several 

research groups’ papers are listed in the bibliography that discuss different strain work. 

33McMillan, J.; Tucker, M.; Hayward, T.; Newman, M.; Ruth, M.; Farmer, J. “Demonstrate 

process technology meeting or exceeding process qualifier performance in the mini-pilot 

biochemical conversion system and assess continuous SSCF performance to recommend future 

work,” Internal Report, National Renewable Energy Laboratory C milestone to DOE, October 

1997. Duplicate SSCF runs were demonstrated in the mini pilot fermentation system using an 

initial total solids loading of almost 20%. 

34 This is the titer of the enzyme used in the NREL pilot facility, purchased from Iogen in 1995. 

35 McMillan, J.D., M.P. Tucker, T.K. Hayward, C. Hatzis, and D. Glassner. “Process Qualifier 

Milestone,” Internal Report, National Renewable Energy Laboratory, Golden, CO, 31 August 

1996, Experiment PD 23 #3. 

36 McMillan, J.D., M.P. Tucker, T.K. Hayward, C. Hatzis, and D. Glassner. “Process Qualifier 

Milestone,” Internal Report, National Renewable Energy Laboratory, Golden, CO, 31 August 

1996, Experiment PD 23 #3. PD 23 #3 utilized a 24-hr residence time for seed production. 

37 Kern, D.Q., Process Heat Transfer, McGraw-Hill, New York, 1950, pp. 720-723. 

38 The seed reaction yields were assumed to be the same as fermentation yields in the ethanol 

production fermentors with increased cell mass production. Therefore the cell mass production 

was increased to 4% from both glucose and xylose and the xylose to products yield was 

reduced to allow more xylose to be converted to cell mass. 

39 The CSL loading used in McMillan, J.D., M.P. Tucker, T.K. Hayward, C. Hatzis, and D. 

Glassner, Process Qualifier Milestone, August 31, 1996, experiment PD 23 #3 was 1% clarified 

CSL. The experiment titled Nutrient Screen #2 for recombinant Zymo 39676pZB4L conducted 

by the Enzymatic Process Development (EPD) team during fiscal year 1998 showed that 0.25% 

CSL was as effective as 1% CSL, so 0.25% CSL is used in the model. 

40 Diammonium phosphate (DAP) is an inorganic nutrient typically added to SSCF experiments 

for nitrogen augmentation. It is typically provided at a concentration of 0.33 g/L as evident by 

Newman, M. “Three dry nutrient supplements obtained from the Marcor Corporation were 

tested and growth curves compared to media containing liquid CSL using the adapted strain 

rZymomonas39676 (pZB 4L)”, Internal Report, National Renewable Energy Laboratory, 

Golden, CO, 20 September 2000. Notebook #2301, pp. 80-84. EPD experiment #EPD0007. 

85 
41 A loss of 3% of the fermentable sugars to non-ethanol products, such as lactic acid, is estimated 

based on conversations with corn ethanol producers who indicate they can tolerate a 

contamination loss less then 3%. 

42 G. Brodl, P. Tetarenko, Vogelbusch, USA, personal communications with M. Ruth, 1998. 

43 Combs, N., McMillan, J. “LAP Procedures #8 - SSF Experimental Protocols: Lignocellulosic 

Biomass Hydrolysis and Fermentation,” Published Procedure, 30 October 2001. 

http://www.afdc.doe.gov/pdfs/4691.pdf. The LAP analysis resulted in 87.2% measured 

conversion of insoluble glucan to ethanol. Assuming 3% loss of converted sugars to nonethanol pathway products (e.g., cell mass and glycerol), the insoluble glucan to glucose 

conversion is 90%. The other yields were measured in a full mass-balanced experiment on 

yellow poplar that is listed in the reference. 

44 Dowe, N., “EPD0005: A Material Balance of the SSCF Using Whole In-house Cellulase Broth 

and Partially Washed Pretreated Yellow Poplar,” Internal Report, National Renewable Energy 

Laboratory Experimental Report, March 2002. 

45 Aersten, F., and G. Street, Applied Chemical Process Design, Plenum Press, New York, 1978. 

46 “Wastewater Treatment Options for the Biomass-To-Ethanol Process,” NREL Subcontract 

AXE-8-18020-01, Merrick & Company, Aurora, CO, February 24, 1998. 

http://www.ott.doe.gov/biofuels/process_engineering.html pp. 9-10. Three samples were 

analyzed for components and tested (in triplicate) for COD. The COD calculated from 

composition was 28,398 mg/L and the average measured CID was 27,199 mg/L. 

47 http://my.ohio.voyager.net/~combs/arr/fp/tankcars.html 

48 “Baled Feedstock Handling System,” report no. 99-10600/13, NREL Subcontract ACO-9-

29067-01, Harris Group Inc., Seattle, WA, October 11, 2001. Found in Appendix G, vendor is 

Northwest Handling Systems, Inc. http://www.ott.doe.gov/biofuels/process_engineering.html 

49 “Biomass-To-Ethanol Total Energy Cycle Analysis,” NREL Subcontract RCN 213-185-01-00 

Final Report, Radian Corporation, Austin, TX, November 22, 1991. 

http://www.ott.doe.gov/biofuels/process_engineering.html 

50 Fluidized Bed Combustion and Gasification: A Guide for Biomass Waste Users, Southeastern 

Regional Biomass Energy Program, FBT, Inc and Tennessee Valley Authority, Muscle Shoals, 

AL, July 1994. http://www.ott.doe.gov/biofuels/process_engineering.html 

51 K. Ibsen, personal experience based on literature survey focused toward biomass residue 

combustion, 1998. 

52 “Economic Feasibility Study of an Acid Hydrolysis-Based Ethanol Plant,” NREL subcontract 

ZX-3-03096-2 Final Report, Badger Engineers, Inc., Cambridge, MA, April 1987. 

http://www.ott.doe.gov/biofuels/process_engineering.html 

53 “ASPEN Modeling of the NREL Boiler/Turbogenerator Systems,” NREL Consultant 

Agreement CXL-8-18051-01, Final Report, V. Putsche, February 1998. 

54 Babcock & Wilcox, 1978, Steam: It’s Generation and Use Thirty-ninth Edition. Babcock & 

Wilcox Company, New York, NY, p. 34/10-16. 

55 Phillippek, C. et al, 1997. “NOx Formation and Reduction During Combustion of Wet Sewage 

Sludge in the Circulating Fluidized Bed,” 1997 Fluidized Bed Combustion vol. 2, ASME 1997. 

86 
56Process Plant Construction Estimating Standards, electronic version section 100-374, 

Richardson Engineering Services, Inc., Mesa, AZ, 1999. 

57 “Biomass to Ethanol Process Evaluation,” NREL Final Subcontract Report, Chem Systems, 

Tarrytown, NY, Appendix V, December 1994. 

http://www.ott.doe.gov/biofuels/process_engineering.html 

58 W. Campbell, Foster Wheeler Corporation, Cost Quotation, Proposal 0-02-43731, to V. 

Putsche, NREL, September 30, 1994. 

59 “Technical and Economic Evaluation: Wood to Ethanol Process,” SERI Subcontract Report, 

Chem Systems, Tarrytown, NY, August 1990. 

http://www.ott.doe.gov/biofuels/process_engineering.html 

60 Sheehan, J., “Analysis of Regional Conditions for Cooling Water Used in Ethanol Production 

Technology,” Internal Report, National Renewable Energy Laboratory, Golden, CO, January 

1998. 

61 MacFarlane, B., “Calculation of an Overall Carbon Balance for the Ethanol Production 

Process,” Internal Report, National Renewable Energy Laboratory Technical Memo, June 

2001. 

62 MacFarlane, B., “Calculation of the Overall Energy Balance for the Ethanol Production 

Process,” Internal Report, National Renewable Energy Laboratory Technical Memo, December 

2001. 

63 Peters, M.S. and K.D. Timmerhaus, Plant Design and Economics for Chemical Engineers, 4th 

Edition, McGraw-Hill, Inc., New York, 1991. 

64 “Biomass to Ethanol Process Evaluation,” NREL Final Subcontract Report, Chem Systems, 

Tarrytown, NY, December 1994. http://www.ott.doe.gov/biofuels/process_engineering.html 

65 Walas, S. M., Chemical Process Equipment Selection and Design, Butterworth Publishing, 

1988. 

66 “Process Design and Cost Estimate of Critical Equipment in the Biomass to Ethanol Process,” 

NREL Final Subcontract Report, Harris Group Inc., Seattle, WA, March 2001. 

67 Energy Information Administration, Annual Energy Outlook 2001 with Projections to 2020. 

U.S. Department of Energy, Washington, DC, 2000. http://www.eia.doe.gov/oiaf/aeo/ 

68 “Chemical Engineering Plant Cost Index,” Chemical Engineering, January 2001. 

69 “Biomass to Ethanol Process Evaluation,” NREL Final Subcontract Report, Chem Systems, 

Tarrytown, NY, p. VI-3, December 1994. 

70 “U.S. Producer Price Indexes – Chemicals and Allied Products/Industrial Inorganic Chemicals 

Index,” from the Chemical Economics Handbook, published by SRI Consulting, a division of 

SRI International, Menlo Park, CA, October 1997. 

71Bureau of Labor Statistics Data Web site (www.stats.bls.gov), National Employment, Hours, 

and Earnings Catalog, Industry: Chemicals and Allied Products. Series ID: EEU32280006, 

Years: 1980 - 2000, annual average. Data extracted on March 1, 2001. 

72 Short, W., D.J. Packey, and T. Holt, “A Manual for the Economic Evaluation and Energy 

Efficiency and Renewable Energy Technologies,” National Renewable Energy Laboratory, 

Golden, CO, Report TP-462-5173, p.7, March 1995. 

87 
73 Short, W., D.J. Packey, and T. Holt, “A Manual for the Economic Evaluation and Energy 

Efficiency and Renewable Energy Technologies,” National Renewable Energy Laboratory, 

Golden, CO, Report TP-462-5173, p. 19, March 1995. 

74 Short, W., D.J. Packey, and T. Holt, “A Manual for the Economic Evaluation and Energy 

Efficiency and Renewable Energy Technologies,” National Renewable Energy Laboratory, 

Golden, CO, Report TP-462-5173, pp. 20-21, March 1995. 

75 Perry, R. H., and D. W. Green, Perry’s Chemical Engineers’ Handbook, 7th Edition, McGrawHill, New York, pp. 9-76, 1997. 

76 Gary, J. H., and G. E. Handwerk, Petroleum Refining, Technology and Economics, 3rd Edition, 

Marcel Dekker, Inc., New York, 1994. 

77 Ibsen, K. “Publish results of Bridge to Corn Ethanol Subcontracts,” Internal Report, National 

Renewable Energy Laboratory P milestone, February 2001. 

78 Reported as runs #1 and #2 in Schell, D.J., J. Farmer, M. Newman, and J.D. McMillan. “Dilute 

Sulfuric Acid Pretreatment of Corn Stover in a Pilot-Scale Reactor: Investigation of Yields, 

Kinetics, and Solids Enzymatic Digestibilities” presented at the Twenty-Fourth Symposium on 

Biotechnology for Fuels and Chemicals (Gatlinburg, TN, April-May 2002) and submitted to the 

conference proceedings which will be published in the Spring 2003 edition of Applied 

Biochemistry and Biotechnology. 

79 Comments from ethanol producers to J. Ashworth at the Enzyme Sugar Platform gate review 

meeting held in 2002 suggest that $0.02/kWh is in the range for long term power purchase and 

sales contracts in key states (Nebraska, Kansas). $0.06/kWh is below the industrial rate of 

many East coast utilities currently, so it represents a reasonable high-end value. 

80 Douglas, Larry J. “Monte Carlo Simulation as a Research Management Tool.” TAPPI 

Proceedings of the 1986 Research and Development Conference. pp. 65-71. 

81 Akerberg, Christina; and Zacchi, G. “An economic evaluation of the fermentation production 

of lactic acid from wheat flour.” Bioresource Technology 75 (2000) 119-126. 

82Crystal BallTM, Release 2000.1 Professional Edition, Decisioneering, Inc., Denver, CO, 

September 2000. 

83 Excel TM, Release 2000, Microsoft Corporation, Seattle, WA, 2000. 

88 
Appendix A 

NREL Biofuels Process Design Database 

Description and Summary 
Appendix A NREL Process Design Database Description and Summary 

NREL’s Process Engineering Team has developed a database of primary information on all of the 

equipment in the benchmark model. This database contains information about the cost, reference year, 

scaling factor, scaling characteristic, design information and back-up cost referencing. The information is 

stored in a secure database in the Biotechnology Center for Fuels and Chemicals and can be directly linked 

to the economic portion of the model. In addition to having all of the cost information used by the model, it 

has the ability to store documents pertaining to the piece of equipment. These include sizing and costing 

calculations and vendor information when available. 

The following summarizes the important fields of information contained in the database. A partial listing 

of the information is attached for each piece of equipment. Additional information from the database is 

contained in the equipment cost listing in Appendix B. 

Equipment Number:AB Unique identifier, the first letter indicates the equipment type and the first 

number represents the process area, e.g., P-301 is a pump in Area 300 

Equipment Name:AB Descriptive name of the piece of equipment 

Associated PFD: PFD number on which the piece of equipment appears, e.g., PFD-P110-A101 

Equipment Category:A Code indicating the general type of equipment, e.g., PUMP 

Equipment Type:A Code indicating the specific type of equipment, e.g., CENTRIFUGAL for a 

pump 

Equipment Description:A Short description of the size or characteristics of the piece of equipment, e.g., 

20 gpm, 82 ft head for a pump 

Number Required:B Number of duplicate pieces of equipment needed 

Number Spares:B Number of on-line spares 

Scaling Stream:B Stream number or other characteristic variable from the ASPEN model by 

which the equipment cost will be scaled 

Base Cost:B Equipment cost 

Cost Basis:A Source of the equipment cost, e.g., ICARUS or VENDOR 

Cost Year:B Year for which the cost estimate is based 

Base for Scaling:B Value of the scaling stream or variable used to obtain the base cost of the 

equipment 

Base Type: Type of variable used for scaling, e.g., FLOW, DUTY, etc. 

Base Units: Units of the scaling stream or variable, e.g., KG/HR, CAL/S 

Installation Factor:B Value of the installation factor. Installed Cost = Base Cost x Installation 

Factor 

Installation Factor Basis: Source of the installation factor value, e.g., ICARUS, VENDOR 

Scale Factor Exponent:B Value of the exponential scaling equation 

Scale Factor Basis: Source of the scaling exponent value, e.g., GARRETT, VENDOR 

Material of Construction:A Material of Construction 

Notes: Any other important information about the design or cost 

Document: Complete, multi-page document containing design calculations, vendor 

literature and quotations and any other important information. This is stored 

as an electronic document and can be pages from a spreadsheet other 

electronic sources or scanned information from vendors. 

Design Date: Original date for the design of this piece of equipment 

Modified Date: The system automatically marks the date in this field whenever any field is 

changed 

A These fields are listed for all pieces of equipment in this Appendix. B These fields are part of the equipment cost listing in Appendix B. 
NREL Biofuels Process Design Database Summary 

Equipment 

Number Equipment Name Equipment Category Equipment Type Equipment Description Cost Basis Install. Factor Basis Scale Factor Basis Material of Construction 

PFD-P110-A101 

C-101 Bale Transport Conveyor CONVEYOR BELT Bale Transport Conveyor, 400 ft long, 8' wide, 50 HP motor HARRIS00 HARRIS00 DEFAULT CS 

C-102 Bale Unwrapping Conveyor CONVEYOR BELT Bale Unwrapping Conveyor, 90 bale / hr HARRIS00 HARRIS00 DEFAULT CS 

C-103 Belt Press Discharge Conveyor CONVEYOR BELT Belt Press Discharge Conveyor, 3' wide X 50' long. HARRIS00 HARRIS00 DEFAULT CS 

C-104 Shredder Feed Conveyor CONVEYOR BELT Shredder Feed Conveyor, 8' wide X 30' long. 6001 lbs 31 fpm HARRIS00 HARRIS00 DEFAULT CS 

M-101 Truck Scales SCALE TRUCK-SCALE Truck Scales; 10' X 50' 50tn HARRIS00 HARRIS00 DEFAULT CONCRETE 

M-102 Truck Unloading Forklift VEHICLE LOADER Truck Unloading Propane Gas Forklift HARRIS00 HARRIS00 ASSUMED 

M-103 Bale Moving Forklift VEHICLE LOADER Bale Moving Propane Gas Forklift HARRIS00 HARRIS00 ASSUMED 

M-104 Corn Stover Wash Table SIZE-REDUCTION Corn Stover Wash Table (55 ton/hr) HARRIS00 HARRIS00 DEFAULT A283 

M-105 Shredder SIZE-REDUCTION Shredder (28 ton/hr) HARRIS00 HARRIS00 DEFAULT ALLOY STEEL 

M-106 Concrete Feedstock-Storage Slab MISCELLANEOUS CONCRETE-SLAB Concrete Feedstock-Storage Slab 350' X 538' HARRIS00 HARRIS00 HARRIS00 CONCRETE 

M-107 Polymer Feed System MISCELLANEOUS MISCELLANEOUS Polymer Feed System HARRIS00 HARRIS00 DEFAULT CS 

P-101 Wash Table Pump PUMP CENTRIFUGAL 2500 gpm, 50 ft head. HARRIS00 HARRIS00 GARRETT CS; RUBBER 

P-102 Wash Water Pump PUMP CENTRIFUGAL 5000 gpm, 50 ft head. HARRIS00 HARRIS00 GARRETT CS; SS316 

P-103 Clarifier Underflow Pump PUMP RECIPROCATING Clarifier Underflow Pump MOD SRL 2X3-10 100 GPM -- 50 TDH HARRIS00 HARRIS00 GARRETT CS; RUBBER 

P-104 Clarified Water Pump PUMP CENTRIFUGAL 5000 gpm, 50 ft head. HARRIS00 HARRIS00 GARRETT CS; SS316 

P-105 Belt Press Sump Pump PUMP SLURRY Belt Press Sump Pump VJC 1.5X2.11 100 GPM -- 40 TDH HARRIS00 HARRIS00 GARRETT CS 

S-101 Clarifier Thickener SEPARATOR Clarifier Thickener 5000 GPM mechanism HARRIS00 HARRIS00 DEFAULT CS 

S-102 Belt Press S/L SEPARATION FILTER-PRESS Belt Press 1.5 meter HARRIS00 HARRIS00 DEFAULT 304SS; FILTER 

S-103 Magnetic Separator SEPARATOR MAGNET Tramp iron magnet separator. VENDOR DELTA-T98 DEFAULT 

T-101 Wash Water Tank TANK VERTICAL-VESSEL Wash Water Tank (20' Diameter X 22' Tall, 50,000 gal) HARRIS00 HARRIS00 GARRETT CS 

T-102 Clarifier Thickener Tank TANK CLARIFER Clarifier Thickener Tank (80' diameter) HARRIS00 HARRIS00 GARRETT CEMENT 

PFD-P110-A201-3 

A-201 In-line Sulfuric Acid Mixer MIXER STATIC Static Mixer, 248 gpm total flow. ICARUS DELTA-T98 ICARUS SS304 

A-205 Hydrolysate Mix Tank Agitator AGITATOR FIXED-PROP Top-Mounted, 1800 rpm, 50 hp ICARUS DELTA-T98 GARRETT SS 

A-209 Overliming Tank Agitator AGITATOR FIXED-PROP Top Mounted, 1800 rpm, 25 hp ICARUS DELTA-T98 GARRETT SS 

A-224 Reacidification Tank Agitator AGITATOR FIXED-PROP Top-Mounted, 1800 rpm, 93 hp ICARUS DELTA-T98 GARRETT SS 

A-232 Reslurrying Tank Agitator AGITATOR FIXED-PROP Top-Mounted, 1800 rpm, 50 hp ICARUS DELTA-T98 GARRETT SS 

C-201 Hydrolyzate Screw Conveyor CONVEYOR SCREW 18" dia. X 33' long, 7600 cfh max flow ICARUS DELTA-T98 GARRETT SS316 

C-202 Hydrolysate Washed Solids Belt Conveyor CONVEYOR BELT 4' X 60' belt conveyor HARRIS00 HARRIS00 GARRETT 

C-225 Lime Solids Feeder CONVEYOR ROTARY-VALVE 8" dia., 140 cfh, 7000 lb/hr max flow ICARUS DELTA-T98 A285C 

H-200 Hydrolyzate Cooler HEATX SHELL-TUBE Fixed Tube Sheet,1990 sf, 27" dia. X 20' long ICARUS DELTA-T98 GARRETT 304SS;CS 

H-201 Beer Column Feed Economizer HEATX SHELL-TUBE Floating Head, 6266 sf, 48" dia x 23' long ICARUS DELTA-T98 GARRETT 304SS 

H-205 Pneumapress Vent Condensor HEATX SHELL-TUBE Fixed Tube Sheet, 120 sf, CS construction ICARUS DELTA-T98 GARRETT CS 

H-244 Waste Vapor Condensor HEATX SHELL-TUBE Floating Head, 6266 sf, 48" dia x 23' long ICARUS DELTA-T98 GARRETT 304SS 

M-202 Prehydrolysis/Screw Feeder/Impregnator Reactor REACTOR SCREW Vertical Screw, 10 min residence time VENDOR CHEMSYST94 GARRETT HASTELLOY-C 200;SS316L 

P-201 Sulfuric Acid Pump PUMP CENTRIFUGAL 4 gpm, 245 ft. head ICARUS DELTA-T98 GARRETT SS304 

P-205 Pneumapress Feed Pump PUMP CENTRIFUGAL Goulds Mod 3196 ^X8-13 1000 gpm 60 ft TDH 25 hp 1200 RPM HARRIS00 HARRIS00 GARRETT SS316 

P-209 Overlimed Hydrolyzate Pump PUMP CENTRIFUGAL 687 gpm, 150 ft. head ICARUS DELTA-T98 GARRETT 304SS 

P-211 Primary Filtrate Pump PUMP CENTRIFUGAL Goulds Mod 3410 10X12-17 1000 GPM 60 ft TDH HARRIS00 HARRIS00 GARRETT SS316 

P-213 Wash Filtrate Pump PUMP CENTRIFUGAL Goulds Mod 3410 10X12-17 6000 GPM 200 ft TDH HARRIS00 HARRIS00 GARRETT SS316 

P-222 Filtered Hydrolyzate Pump PUMP CENTRIFUGAL 721 gpm, 150 ft head ICARUS DELTA-T98 GARRETT 304SS 

P-223 Lime Unloading Blower FAN CENTRIFUGAL 7425 cfm, 6 psi, 22275 lb/hr DELTA-T98 DELTA-T98 GARRETT C.S. 

P-224 Fermentation Feed Pump PUMP ROTARY-LOBE 737 gpm, 200 ft head VENDOR ICARUS VENDOR 304SS 

P-239 Reacidified Liquor Pump PUMP CENTRIFUGAL 720 gpm, 100 ft head ICARUS DELTA-T98 GARRETT SS304 

S-205 Pneumapress Filter SEPARATOR PNEUMAPRESS MOD 30-12-316 285 GPM 360 SQ FT AREA HARRIS00 HARRIS00 DEFAULT SS316 

S-222 Hydroclone & Rotary Drum Filter S/L SEPARATOR ROTARY-DRUM Hydrocyclone and Vacuum Filter VENDOR DELTA-T98 GARRETT EPOXY LINED 

S-227 LimeDust Vent Baghouse SEPARATOR FABRIC-FILTER 8333 cfm, 1389 sf, 6 cfm/sf ICARUS DELTA-T98 ICARUS A285C;POLYESTER 

T-201 Sulfuric Acid Storage TANK VERTICAL-VESSEL 6444 gal., 24 hr. residence time, 90% wv DELTA-T98 DELTA-T98 GARRETT PLASTIC 

T-203 Blowdown Tank TANK VERTICAL-VESSEL 14500 gal., 11' dia x 30' high, 10 min. res. time, 75% wv, 15 psig ICARUS ICARUS GARRETT SS316 

T-205 Hydrolysate Mixing Tank TANK FLAT-BTM-STORAGE Modeled after Tank T-232 in Enzyme Process. 15 min. res. Time ICARUS DELTA-T98 GARRETT SS304 

T-209 Overliming Tank TANK VERTICAL-VESSEL 46200 gal., 16' dia. X 32' high, 1 hr. res. time, 90% wv, 15 psig ICARUS DELTA-T98 GARRETT SS304 

T-211 Primary Filtrate Tank TANK VERTICAL-VESSEL 12'6" D X 13' high 12,000 gal HARRIS00 HARRIS00 GARRETT SS316 

T-213 Wash Filtrate Tank TANK VERTICAL-VESSEL 10' D X 11' high 6000 gal HARRIS00 HARRIS00 GARRETT SS316 

T-220 Lime Storage Bin TANK LIVE-BTM-BIN 4455 cf, 14' dia x 25' high, 1.5x rail car vol., atmospheric ICARUS DELTA-T98 ICARUS CS 

T-224 Reacidification Tank TANK FLAT-BTM-STORAGE 185200 gal., 32' dia x 32' high, 4 hr. res. time, 90% wv, atmospheric ICARUS DELTA-T98 GARRETT SS304 

T-232 Slurrying Tank TANK FLAT-BTM-STORAGE 24770 gal., 13' dia. X 25' high, 15 min. res. time, 90% wv, atmospheric ICARUS DELTA-T98 GARRETT SS304 

Note: Equipment sizes listed are for a base case and may have been scaled up or down in the final cost estimation. Appendix A - Page 1
NREL Biofuels Process Design Database Summary 

Equipment 

Number Equipment Name Equipment Category Equipment Type Equipment Description Cost Basis Install. Factor Basis Scale Factor Basis Material of Construction 

PFD-P110-A301-2 

A-300 Ethanol Fermentor Agitator AGITATOR FIXED-PROP Side Mounted, 2 per vessel, 75 hp each, 0.15 hp/1000 gal DELTA-T98 DELTA-T98 SS304 

A-301 Seed Hold Tank Agitator AGITATOR FIXED-PROP Top Mounted, 1800 rpm, 23 hp, 0.1 hp/1000 gal DELTA-T98 DELTA-T98 GARRETT SS304 

A-304 4th Seed Vessel Agitator AGITATOR FIXED-PROP Top Mounted, 1800 rpm, 6 hp, 0.3 hp/1000 gal ICARUS DELTA-T98 GARRETT SS 

A-305 5th Seed Vessel Agitator AGITATOR FIXED-PROP Top Mounted, 1800 rpm, 19 hp, 0.1 hp/1000 gal DELTA-T98 DELTA-T98 GARRETT SS 

A-306 Beer Surge Tank Agitator AGITATOR FIXED-PROP Top Mounted, 1800 rpm, 4 hp, 0.3 hp/1000 gal ICARUS DELTA-T98 GARRETT SS304 

A-310 Saccharification Tank Agitator AGITATOR FIXED-PROP Side Mounted, 2 per vessel, 75 hp each, 0.15 hp/1000 gal DELTA-T98 DELTA-T98 SS304 

F-300 Ethanol Fermentor TANK FLAT-BTM-STORAGE 962,651 gal. each, 7 day residence total, 90% wv, API, atmospheric VENDOR DELTA-T98 MULTI-UNIT SS304 

F-301 1st Seed Fermentor REACTOR VERTICAL-VESSEL 20 gal, jacketed, agitated, 1.3' dia., 2' high, 15 psig ICARUS DELTA-T98 SS304 

F-302 2nd Seed Fermentor REACTOR VERTICAL-VESSEL 194 gal., jacketed, agitated, 3' dia., 4' high, 2.5 psig ICARUS ICARUS SS304 

F-303 3rd Seed Fermentor REACTOR VERTICAL-VESSEL 1950 gal., jacketed, agitated, 6.5' dia, 8' high, 2.5 psig ICARUS DELTA-T98 SS304 

F-304 4th Seed Fermentor REACTOR FLAT-BTM-STORAGE 19444 gal., 12' dia x 23' high, atmospheric ICARUS DELTA-T98 GARRETT SS304 

F-305 5th Seed Fermentor REACTOR FLAT-BTM-STORAGE 194500 gal., API, atmospheric VENDOR DELTA-T98 GARRETT SS304 

H-300 Fermentation Cooler HEATX PLATE-FRAME 2393 sf, 300 BTU/hr sf F ICARUS DELTA-T98 GARRETT SS304 

H-301 Hydrolyzate Heater HEATX PLATE-FRAME 773 sf, 300 BTU/hr sf F DELTA-T98 DELTA-T98 GARRETT SS304 

H-302 Saccharified Slurry Cooler HEATX PLATE-FRAME 3765 sf total, 1255 sf each, 300 BTU/hr sf F DELTA-T98 DELTA-T98 GARRETT SS304 

H-304 4th Seed Fermentor Coils HEATX IMMERSED-COIL 27 sf, 1" sch 40 pipe, 105 BTU/hr sf F ICARUS DELTA-T98 ICARUS SS 

H-305 5th Seed Fermentor Coils HEATX IMMERSED-COIL 307 sf, 3" sch 40 pipe, 92 BTU/hr sf F ICARUS DELTA-T98 ICARUS SS 

H-310 Fermentation Cooler HEATX PLATE-FRAME 2393 sf, 300 BTU/hr sf F ICARUS DELTA-T98 GARRETT SS304 

P-300 Fermentation Recirculation and Transfer Pump PUMP CENTRIFUGAL 1060 gpm, 150 ft head ICARUS DELTA-T98 GARRETT SS304 

P-301 Seed Hold Transfer Pump PUMP ROTARY-LOBE 172 gpm, 150 ft head VENDOR CHEMSYST94 VENDOR SS304 

P-302 Seed Transfer Pump PUMP ROTARY-LOBE 1231 gpm total, 615 gpm each, 100 ft head VENDOR CHEMSYST94 VENDOR SS304 

P-306 Beer Transfer Pump PUMP CENTRIFUGAL 1632 gpm each, 171 ft head ICARUS DELTA-T98 GARRETT SS304 

P-310 Saccharification Recirculation and Transfer Pump PUMP CENTRIFUGAL 1060 gpm, 150 ft head ICARUS DELTA-T98 GARRETT SS304 

T-301 Seed Hold Tank TANK FLAT-BTM-STORAGE 233,333 gal., API atmospheric VENDOR DELTA-T98 GARRETT SS304 

T-306 Beer Storage Tank TANK FLAT-BTM-STORAGE 456617 gal., 45' dia x 40' high, 4 hr res. Time, 90% wv, atmospheric ICARUS DELTA-T98 GARRETT SS304 

T-310 Saccharification Tank TANK FLAT-BTM-STORAGE 962,651 gal. each, 7 day residence total, 90% wv, API, atmospheric VENDOR DELTA-T98 MULTI-UNIT SS304 

PFD-P110-A501-5 

A-530 Recycled Water Tank Agitator AGITATOR FIXED-PROP 5 hp, 50 rpm, VENDOR DELTA-T98 GARRETT CS 

C-501 Lignin Wet Cake Screw CONVEYOR SCREW 14" Dia X 100' Long ICARUS DELTA-T98 GARRETT CS 

D-501 Beer Column COLUMN DISTILLATION 13.5' dia, 32 Actual Trays, Nutter V-Grid Trays ICARUS DELTA-T98 ICARUS SS304 

D-502 Rectification Column COLUMN DISTILLATION 11.5' dia.(rect)., 4' dia. (strip) x 18" T.S., 60 act. Trays, 60% eff., Nutter V-Grid trays DELTA-T98 DELTA-T98 ICARUS SS 

E-501 1st Effect Evaporation HEATX SHELL-TUBE 22280 sf each., 135 BTU/hr sf F DELTA-T98 DELTA-T98 GARRETT SS316 

E-502 2nd Effect Evaporation HEATX SHELL-TUBE 22278 sf., 170 BTU/hr sf F DELTA-T98 DELTA-T98 GARRETT SS316 

E-503 3rd Effect Evaporation HEATX SHELL-TUBE 22278 sf each., 170 BTU/hr sf F DELTA-T98 DELTA-T98 GARRETT SS316 

H-501 Beer Column Reboiler HEATX SHELL-TUBE Fixed TS, 13899 sf, 41" dia., 20' long, 178 BTU/hr sf F DELTA-T98 DELTA-T98 GARRETT SS304;CS 

H-502 Rectification Column Reboiler HEATX SHELL-TUBE Thermosyphon, 1089 sf, 20" dia., 20' long, 130 BTU/hr sf F ICARUS DELTA-T98 GARRETT SS304;CS 

H-504 Beer Column Condenser HEATX SHELL-TUBE Floating Head, 880 sf, 20" dia., 22' long, 92 BTU/hr sf F DELTA-T98 DELTA-T98 GARRETT SS304;CS 

H-505 Rectification Column Condenser HEATX SHELL-TUBE Fixed TS, 4146 sf, 39" dia, 20' long, 157 BTU/hr sf F DELTA-T98 DELTA-T98 GARRETT SS304;CS 

H-512 Beer Column Feed Interchange HEATX PLATE-FRAME 909 sf, 200 BTU/hr sf F DELTA-T98 DELTA-T98 GARRETT SS 

H-517 Evaporator Condenser HEATX SHELL-TUBE Fixed TS, 8223 sf, 39" dia., 20' long, 220 BTU/hr sf F DELTA-T98 DELTA-T98 GARRETT SS304;CS 

M-503 Molecular Sieve (9 pieces) MISCELLANEOUS PACKAGE Superheater, twin mole sieve columns, product cooler, condenser, pumps, vacuum source. VENDOR DELTA-T98 SS 

P-501 Beer Column Bottoms Pump PUMP CENTRIFUGAL 5053 gpm, 150 ft head ICARUS ICARUS GARRETT SS 

P-503 Beer Column Reflux Pump PUMP CENTRIFUGAL 12 gpm, 140 ft head DELTA-T98 DELTA-T98 GARRETT SS 

P-504 Rectification Column Bottoms Pump PUMP CENTRIFUGAL 154 gpm, 158 ft head DELTA-T98 DELTA-T98 GARRETT SS 

P-505 Rectification Column Reflux Pump PUMP CENTRIFUGAL 437 gpm, 110 ft head DELTA-T98 DELTA-T98 GARRETT SS 

P-511 1st Effect Pump PUMP CENTRIFUGAL 2393 gpm each, 110 ft head ICARUS DELTA-T98 GARRETT SS 

P-512 2nd Effect Pump PUMP CENTRIFUGAL 1261 gpm, 110 ft head ICARUS DELTA-T98 GARRETT SS 

P-513 3rd Effect Pump PUMP CENTRIFUGAL 412 gpm each, 110 ft head ICARUS DELTA-T98 GARRETT SS 

P-514 Evaporator Condensate Pump PUMP CENTRIFUGAL 617 gpm, 125 ft head ICARUS DELTA-T98 GARRETT SS304 

P-515 Scrubber Bottoms Pump PUMP CENTRIFUGAL 69 gpm, 104 ft head DELTA-T98 DELTA-T98 GARRETT SS 

P-530 Recycled Water Pump PUMP CENTRIFUGAL 790 gpm, 150 ft head ICARUS DELTA-T98 GARRETT CS 

S-505 Pneumapress Filter SEPARATOR PNEUMAPRESS 3@MOD 30-10-316 285 GPM 300 SQ FT AREA & 1@MOD 30-11-316 314 GPM 314 SQ FT AREA HARRIS00 HARRIS00 DEFAULT SS316 

T-503 Beer Column Relfux Drum TANK HORIZONTAL-VESSEL 346 gal, 15 min res. Time, 50% wv, 3' dia., 6.5' long, 25 psig ICARUS DELTA-T98 GARRETT SS304 

T-505 Rectification Column Reflux Drum TANK HORIZONTAL-VESSEL 13106 gal, 15 min res time, 50% wv, 9' dia, 27.5' long, 25 psig ICARUS DELTA-T98 GARRETT SS304 

T-512 Vent Scrubber COLUMN ABSORBER 7' dia x 25' high, 4 stages, plastic Jaeger Tri-Packing DELTA-T98 DELTA-T98 GARRETT SS304;PLASTIC 

T-514 Evaporator Condensate Drum TANK HORIZONTAL-VESSEL 10233 gal, 10 min res. Time, 75% wv, 9' dia., 21.5' long, 1 psig ICARUS DELTA-T98 GARRETT SS304 

T-530 Recycled Water Tank TANK FLAT-BTM-STORAGE 13218 gal, Residence time 20 min, 2.5 psig VENDOR DELTA-T98 VENDOR CS 

Note: Equipment sizes listed are for a base case and may have been scaled up or down in the final cost estimation. Appendix A - Page 2
NREL Biofuels Process Design Database Summary 

Equipment 

Number Equipment Name Equipment Category Equipment Type Equipment Description Cost Basis Install. Factor Basis Scale Factor Basis Material of Construction 

PFD-P110-A601-2 

A-602 Equalization Basin Agitator AGITATOR FIXED-PROP 38 hp each, Fixed Prop, 0.1 hp/1000 gal ICARUS DELTA-T98 GARRETT SS 

A-606 Anaerobic Agitator AGITATOR FIXED-PROP Fixed Prop, 41 hp, 0.05 hp/1000 gal ICARUS DELTA-T98 GARRETT SS 

A-608 Aerobic Lagoon Agitators AGITATOR SURFACE-AERATOR Twister Surface Aerators, 50 HP ea VENDOR MERRICK98 GARRETT CS 

C-614 Aerobic Sludge Screw CONVEYOR SCREW 9" Dia X 25' Long ICARUS DELTA-T98 GARRETT CS 

H-602 Anaerobic Digestor Feed Cooler HEATX SHELL-TUBE TEMA BES Type, Floating Head ICARUS DELTA-T98 VENDOR SS316;CS 

M-604 Nutrient Feed System MISCELLANEOUS PACKAGE 5 Tanks and Pumps VENDOR VENDOR CS 

M-606 Biogas Emergency Flare MISCELLANEOUS MISCELLANEOUS Flare and Pilot VENDOR VENDOR DEFAULT SS 

M-612 Filter Precoat System MISCELLANEOUS MISCELLANEOUS Tank, Agitator, Pump MERRICK98 CS 

P-602 Anaerobic Reactor Feed Pump PUMP CENTRIFUGAL 876 gpm, 150 ft head ICARUS DELTA-T98 GARRETT CS 

P-606 Aerobic Digestor Feed Pump PUMP CENTRIFUGAL 830 gpm, 150 ft head ICARUS DELTA-T98 GARRETT CS 

P-608 Aerobic Sludge Recycle Pump PUMP SLURRY 2.5 gpm, 150 ft head ICARUS DELTA-T98 GARRETT SS316 

P-610 Aerobic Sludge Pump PUMP SLURRY 25.3 gpm, 150 ft head ICARUS DELTA-T98 GARRETT SS316 

P-611 Aerobic Digestion Outlet Pump PUMP CENTRIFUGAL 828 gpm, 150' head ICARUS DELTA-T98 GARRETT CS 

P-614 Sludge Filtrate Recycle Pump PUMP CENTRIFUGAL 22 gpm, 150' head ICARUS DELTA-T98 GARRETT CS 

P-616 Treated Water Pump PUMP CENTRIFUGAL 803 gpm, 100 ft head ICARUS DELTA-T98 GARRETT CS 

S-600 Bar Screen SEPARATOR SCREEN 0.5" Mech. cleaned Screen CH2MHL91 DELTA-T98 ASSUMED CS 

S-614 Belt Filter Press S/L SEPARATOR FILTER-PRESS BELT THICKNESS VENDOR VENDOR VENDOR 304SS;BUNA N 

T-602 Equalization Basin TANK FLAT-BTM-STORAGE 377516 gal, Residence time 7.2 hr, VENDOR VENDOR GARRETT CONCRETE 

T-606 Anaerobic Digestor TANK FLAT-BTM-STORAGE 810250 gal each, space velocity 12g COD/L/DAY VENDOR VENDOR GARRETT EPOXY-LINED 

T-608 Aerobic Digestor REACTOR LINED-PIT 19500000 gal, 16.3 day residence time MERRICK98 MERRICK98 POLYMER LINED 

T-610 Clarifier SEPARATOR CLARIFIER 195289 gal, Residence time 3.9 hr. VENDOR VENDOR GARRETT CONCRETE 

PFD-P110-A701 

A-701 Denaturant In-line Mixer MIXER STATIC Static Mixer, total flow 341 gpm ICARUS DELTA-T98 ICARUS SS304 

A-720 CSL Storage Tank Agitator AGITATOR FIXED-PROP Top Mounted, 1800 rpm, 23 hp, 0.1 hp/1000 gal DELTA-T98 DELTA-T98 GARRETT SS304 

A-760 CSL/DAP Day Tank Agitator AGITATOR FIXED-PROP Top Mounted, 1800 rpm, 5 hp, 0.5 hp/1000 gal ICARUS DELTA-T98 GARRETT SS304 

C-755 DAP Solids Feeder CONVEYOR ROTARY-VALVE 8" dia., 140 cfh, 7000 lb/hr max flow ICARUS DELTA-T98 A285C 

P-701 Ethanol Product Pump PUMP CENTRIFUGAL 324 gpm, 112 ft head ICARUS DELTA-T98 GARRETT CS 

P-703 Sulfuric Acid Pump PUMP CENTRIFUGAL 215 gpm, 150 ft head ICARUS DELTA-T98 GARRETT SS316 

P-704 Firewater Pump PUMP CENTRIFUGAL 2500 gpm, 50 ft head ICARUS DELTA-T98 GARRETT CS 

P-710 Gasoline Pump PUMP CENTRIFUGAL 17 gpm, 200 ft head ICARUS DELTA-T98 GARRETT CS 

P-720 CSL Pump PUMP CENTRIFUGAL 431 gpm, 150 ft head ICARUS DELTA-T98 GARRETT CS 

P-750 Cellulase Pump PUMP CENTRIFUGAL 2500 gpm, 50 ft head ICARUS DELTA-T98 GARRETT CS 

P-755 DAP Unloading Blower FAN CENTRIFUGAL 7425 cfm, 6 psi, 22275 lb/hr DELTA-T98 DELTA-T98 GARRETT CS 

P-760 CSL/DAP Pump PUMP CENTRIFUGAL 431 gpm, 150 ft head ICARUS DELTA-T98 GARRETT CS 

S-755 DAP Vent Baghouse SEPARATOR FABRIC-FILTER 8333 cfm, 1389 sf, 6 cfm/sf ICARUS DELTA-T98 ICARUS A285C;POLYESTER 

T-701 Ethanol Product Storage Tank TANK FLAT-BTM-STORAGE 604,133 gal, 7 day res time total, 90% wv, 51' dia x 40' high, atmospheric ICARUS DELTA-T98 GARRETT A285C 

T-703 Sulfuric Acid Storage Tank TANK FLAT-BTM-STORAGE 18697 gal, 120 hr res time, 90% wv, 12' dia x 22' high, atmospheric ICARUS ICARUS GARRETT SS316 

T-704 Firewater Storage Tank TANK FLAT-BTM-STORAGE 600,000 gal, 4 hr res time, 51' dia x 40' high, atmospheric ICARUS DELTA-T98 GARRETT A285C 

T-709 Propane Storage Tank TANK HORIZONTAL STORAGE 2000 gal, 10 day res time, 90% wv, 4' dia x 23.6' length, 250 psig ICARUS DELTA-T98 GARRETT A515 

T-710 Gasoline Storage Tank TANK FLAT-BTM-STORAGE 63,593 gal, 168 hr res time, 90% wv, 19' dia x 32' high, atmospheric ICARUS DELTA-T98 GARRETT A285C 

T-720 CSL Storage Tank TANK FLAT-BTM-STORAGE 71,918 gal, 120 hr res time, 90% wv, 20' dia x 32' high, atmospheric ICARUS ICARUS GARRETT SS304 

T-750 Cellulase Storage Tank TANK FLAT-BTM-STORAGE 130,115 gal, 48 hr res time, 90% wv, 27' dia x 37' high, atmospheric ICARUS ICARUS GARRETT SS304 

T-755 DAP Storage Bin TANK LIVE-BTM-BIN 1425 cf, 9' dia x 19.5' high, 1.5x vessel vol. Req. for 7-day res time, atmospheric ICARUS DELTA-T98 ICARUS CS 

T-760 CSL/DAP Day Tank TANK FLAT-BTM-STORAGE 10,000 gal, 24 hr res time, 90% wv, 9.5' dia x 18.9' high, atmospheric ICARUS ICARUS GARRETT SS304 

PFD-P110-A801-4 

H-801 Burner Combustion Air Preheater MISCELLANEOUS MISCELLANEOUS 37000 sf combustion air/exhaust interchanger ICARUS NREL-ESTM DEFAULT 

H-811 BFW Preheater HEATX SHELL-TUBE Floating Head, 500 SF ICARUS DELTA-T98 GARRETT SS304 

M-803 Fluidized Bed Combustion Reactor MISCELLANEOUS MISCELLANEOUS 900 to 1250 psig/950F Circ. Fluid Bed VENDOR DELTA-T98 VENDOR CS 

M-804 Combustion Gas Baghouse SEPARATOR FABRIC-FILTER Pulse Shaker, 545000 cfm, 135,135 SF VENDOR VENDOR MULTI-UNIT A285C;FABRIC 

M-811 Turbine/Generator GENERATOR STEAM-TURBINE 52-61 MW; 281000 KG/HR STEAM VENDOR DELTA-T98 VENDOR 

M-820 Hot Process Water Softener System MISCELLANEOUS PACKAGE 1000 gpm flow, 24" dia softener. Includes filters, chemical feeders, piping, valves RICHARDSON NREL-ESTM MULTI-UNIT 

M-830 Hydrazine Addition Pkg. MISCELLANEOUS PACKAGE 150 gal tank, agitator, 2 metering pumps CHEMSYST94 CHEMSYST94 DEFAULT 

M-832 Ammonia Addition Pkg MISCELLANEOUS PACKAGE 150 gal tank, agitator, 2 metering pumps CHEMSYST94 CHEMSYST94 DEFAULT 

M-834 Phosphate Addition Pkg. MISCELLANEOUS PACKAGE 150 gal tank, agitator, 2 metering pumps CHEMSYST94 CHEMSYST94 DEFAULT 

P-804 Condensate Pump PUMP CENTRIFUGAL 272 gpm 150' head ICARUS DELTA-T98 GARRETT SS316 

P-811 Turbine Condensate Pump PUMP CENTRIFUGAL 175 gpm, 150 ft head. ICARUS DELTA-T98 GARRETT SS304 

P-824 Deaerator Feed Pump PUMP CENTRIFUGAL 650 gpm, 115 ft head. ICARUS DELTA-T98 GARRETT SS304 

P-826 BFW Pump PUMP CENTRIFUGAL 500 gpm, 2740 ft head. VENDOR DELTA-T98 GARRETT SS316 

P-828 Blowdown Pump PUMP CENTRIFUGAL 29 gpm, 150 ' head ICARUS DELTA-T98 GARRETT CS 

P-830 Hydrazine Transfer Pump PUMP CENTRIFUGAL 5 gpm, 75 ft head DELTA-T98 DELTA-T98 GARRETT CS 

T-804 Condensate Collection Tank TANK VERTICAL-VESSEL 1600 gal, Residence time 1.5 minutes, atmospheric ICARUS DELTA-T98 GARRETT A285C 

T-824 Condensate Surge Drum TANK HORIZONTAL-VESSEL 11,400 gal, 24' x 9'dia, 15psig, Residence time 11 min. ICARUS DELTA-T98 GARRETT SS304 

T-826 Deaerator TANK HORIZONTAL-VESSEL 18,170 gal hold tank, 150 psig design pressure, 10 min residence time VENDOR CHEMSYST94 GARRETT CS;SS316 

T-828 Blowdown Flash Drum TANK HORIZONTAL-VESSEL 424 gal, 4.5' x 4'dia, 15 psig ICARUS DELTA-T98 GARRETT CS 

T-830 Hydrazine Drum TANK VERTICAL-VESSEL 260 gal, 4.9' x 3'dia., 10psig ICARUS DELTA-T98 GARRETT SS316 

Note: Equipment sizes listed are for a base case and may have been scaled up or down in the final cost estimation. Appendix A - Page 3
NREL Biofuels Process Design Database Summary 

Equipment 

Number Equipment Name Equipment Category Equipment Type Equipment Description Cost Basis Install. Factor Basis Scale Factor Basis Material of Construction 

PFD-P110-A901-3 

M-902 Cooling Tower System COOLING-TOWER INDUCED-DRAFT 71000 gpm, 147.8 x E6 kcal/hr, 5 cell DELTA-T98 DELTA-T98 GARRETT FIBERGLASS 

M-904 Plant Air Compressor COMPRESSOR RECIPROCATING 450 cfm, 125 psig outlet ICARUS DELTA-T98 GARRETT CS 

M-910 CIP System MISCELLANEOUS MISCELLANEOUS Designed by Delta-T. Same cost as sum of previous units. DELTA-T98 DELTA-T98 NREL-ESTM CS 

P-902 Cooling Water Pumps PUMP CENTRIFUGAL 41000 gpm, 70 ft head. ICARUS DELTA-T98 GARRETT CS 

P-912 Make-up Water Pump PUMP CENTRIFUGAL 1083 gpm, 75 ft. head ICARUS DELTA-T98 GARRETT CS 

P-914 Process Water Circulating Pump PUMP CENTRIFUGAL 1199 gpm ea, 75 ft. head ICARUS DELTA-T98 GARRETT CS 

S-904 Instrument Air Dryer DRYER PACKAGE 400 SCFM Air Dryer, -40F Dewpoint RICHARDSON DELTA-T98 DEFAULT CS 

T-902 Pretreatment Pressure Filter Press Air Receiver TANK HORIZONTAL-PRESSURE 1000 gal HARRIS00 HARRIS00 GARRETT CS 

T-904 Plant Air Receiver TANK HORIZONTAL-VESSEL 900 gal., 200 psig ICARUS DELTA-T98 GARRETT CS 

T-905 Product Recovery Pressure Filter Press Air Receiver TANKHORIZONTAL-PRESSURE 1000 gal HARRIS00 HARRIS00 GARRETT CS 

T-914 Process Water Tank TANK FLAT-BTM-STORAGE 756000 gal. 8 hr res time ICARUS DELTA-T98 GARRETT CS 

Note: Equipment sizes listed are for a base case and may have been scaled up or down in the final cost estimation. Appendix A - Page 4
Appendix B

Individual Equipment Costs Summary
Individual Equipment Cost Summary 

Equipment 

Number 

Number 

Required 

Number 

Spares Equipment Name Scaled On 

Size 

Ratio 

(Base/ 

Current) 

Original 

Equip Cost 

(per unit) Base Year 

Total Original 

Equip Cost 

(Req'd & 

Spare) in Base 

Year 

Scaling 

Exponent 

Scaled Cost in 

Base Year 

Installation 

Factor 

Installed Cost in 

Base Year 

Installed Cost 

in 2000$ 

C-101 2 Bale Transport Conveyor Flow 1.00 $400,000 2000 $800,000 0.6 $799,996 1.62 $1,295,994 $1,295,994 

C-102 2 Bale Unwrapping Conveyor Flow 1.00 $150,000 2000 $300,000 0.6 $299,999 1.19 $356,998 $356,998 

C-103 1 Belt Press Discharge Conveyor Flow 1.00 $50,000 2000 $50,000 0.6 $50,000 1.89 $94,500 $94,500 

C-104 4 Shredder Feed Conveyor Flow 1.00 $60,000 2000 $240,000 0.6 $239,999 1.38 $331,198 $331,198 

M-101 2 Truck Scales Flow 1.00 $34,000 2000 $68,000 0.6 $68,000 2.47 $167,959 $167,959 

M-102 4 1 Truck Unloading Forklift Flow 1.00 $18,000 2000 $90,000 1 $89,999 1 $89,999 $89,999 

M-103 4 Bale Moving Forklift Flow 1.00 $18,000 2000 $72,000 1 $71,999 1 $71,999 $71,999 

M-104 2 Corn Stover Wash Table Flow 1.00 $104,000 2000 $208,000 0.6 $207,999 2.39 $497,118 $497,118 

M-105 4 Shredder Flow 1.00 $302,000 2000 $1,208,000 0.6 $1,207,994 1.38 $1,667,032 $1,667,032 

M-106 1 Concrete Feedstock-Storage Slab Flow 1.00 $450,655 2000 $450,655 1 $450,651 2.2 $991,433 $991,433 

M-107 1 Polymer Feed System Flow 1.00 $30,000 2000 $30,000 0.6 $30,000 2.28 $68,400 $68,400 

P-101 2 1 Wash Table Pump Flow 1.00 $20,000 2000 $60,000 0.79 $60,000 3.87 $232,199 $232,199 

P-102 2 1 Wash Water Pump Flow 1.00 $15,000 2000 $45,000 0.79 $45,000 5.19 $233,549 $233,549 

P-103 1 1 Clarifier Underflow Pump Flow 1.00 $6,000 2000 $12,000 0.79 $12,000 13.41 $160,919 $160,919 

P-104 1 1 Clarified Water Pump Flow 1.00 $15,000 2000 $30,000 0.79 $30,000 7.07 $212,099 $212,099 

P-105 1 1 Belt Press Sump Pump Flow 1.00 $19,000 2000 $38,000 0.79 $38,000 2.92 $110,959 $110,959 

S-101 1 Clarifier Thickener Flow 1.00 $135,000 2000 $135,000 0.6 $134,999 1.51 $203,849 $203,849 

S-102 1 Belt Press Flow 1.00 $100,000 2000 $100,000 0.6 $100,000 1.25 $124,999 $124,999 

S-103 1 Magnetic Separator Flow 0.61 $13,863 1998 $13,863 0.6 $10,335 1.3 $13,435 $13,594 

T-101 1 Wash Water Tank Flow 1.00 $50,000 2000 $50,000 0.51 $50,000 2.8 $139,999 $139,999 

T-102 1 Clarifier Thickener Tank Flow 1.00 $135,000 2000 $135,000 0.51 $134,999 3.04 $410,398 $410,398 

A100 Subtotal* $4,135,518 $4,131,968 1.81 $7,475,036 $7,475,195 

*Sections are subtotaled and an average "Installation Factor" is back-calculated for the section. Appendix B - Page 1 of 8
Individual Equipment Cost Summary 

Equipment 

Number 

Number 

Required 

Number 

Spares Equipment Name Scaled On 

Size 

Ratio 

(Base/ 

Current) 

Original 

Equip Cost 

(per unit) Base Year 

Total Original 

Equip Cost 

(Req'd & 

Spare) in Base 

Year 

Scaling 

Exponent 

Scaled Cost in 

Base Year 

Installation 

Factor 

Installed Cost in 

Base Year 

Installed Cost 

in 2000$ 

A-201 1 In-line Sulfuric Acid Mixer Flow 1.83 $1,900 1997 $1,900 0.48 $2,542 1 $2,542 $2,592 

A-205 1 Hydrolyzate Mix Tank Agitator Flow 0.63 $36,000 1997 $36,000 0.51 $28,421 1.2 $34,105 $34,775 

A-209 1 Overliming Tank Agitator Flow 1.62 $19,800 1997 $19,800 0.51 $25,349 1.3 $32,953 $33,601 

A-224 1 Reacidification Tank Agitator Flow 1.63 $65,200 1997 $65,200 0.51 $83,599 1.2 $100,318 $102,291 

A-232 1 Reslurrying Tank Agitator Flow 1.19 $36,000 1997 $36,000 0.51 $39,423 1.2 $47,308 $48,238 

C-201 1 Hydrolyzate Screw Conveyor Flow 1.00 $59,400 1997 $59,400 0.78 $59,518 1.3 $77,373 $78,895 

C-202 1 Hydrolysate Washed Solids Belt Conveyor Flow 0.95 $80,000 2000 $80,000 0.76 $77,213 1.45 $111,959 $111,959 

C-225 1 Lime Solids Feeder None $3,900 1997 $3,900 $3,900 1.3 $5,070 $5,170 

H-200 1 Hydrolyzate Cooler Area 0.27 $45,000 1997 $45,000 0.51 $23,266 2.1 $48,859 $49,820 

H-201 2 1 Beer Column Feed Economizer Area 1.16 $132,800 1997 $398,400 0.68 $441,162 2.1 $926,441 $944,658 

H-205 1 Pneumapress Vent Condensor Area 0.84 $15,385 2000 $15,385 0.68 $13,620 2.1 $28,603 $28,603 

H-244 2 1 Waste Vapor Condensor Area 0.24 $132,800 1997 $398,400 0.68 $152,180 2.1 $319,578 $325,863 

M-202 3 Prehydrolysis/Screw Feeder/Reactor Flow 1.03 $2,457,487 2000 $7,372,462 0.6 $7,494,911 2.29 $17,163,347 $17,163,347 

P-201 1 1 Sulfuric Acid Pump Flow 2.00 $4,800 1997 $9,600 0.79 $16,577 2.8 $46,416 $47,328 

P-205 2 1 Pneumapress Feed Pump Solids Flow 0.95 $15,416 2000 $46,248 0.79 $44,579 3.34 $148,893 $148,893 

P-209 1 1 Overlimed Hydrolyzate Pump Flow 1.62 $10,700 1997 $21,400 0.79 $31,377 2.8 $87,855 $89,583 

P-211 1 1 Primary Filtrate Pump Flow 1.02 $32,549 2000 $65,098 0.79 $65,931 3.56 $234,716 $234,716 

P-213 1 1 Wash Filtrate Pump Flow 0.99 $49,803 2000 $99,606 0.79 $98,809 2.71 $267,772 $267,772 

P-222 1 1 Filtered Hydrolyzate Pump Flow 1.64 $10,800 1997 $21,600 0.79 $31,862 2.8 $89,214 $90,968 

P-223 1 Lime Unloading Blower Flow 4.38 $47,600 1998 $47,600 0.5 $99,594 1.4 $139,432 $141,078 

P-224 2 1 Saccharification Feed Pump Flow 1.19 $61,368 1998 $184,104 0.7 $208,550 2.8 $583,941 $590,837 

P-239 1 1 Reacidified Liquor Pump Flow 1.63 $10,800 1997 $21,600 0.79 $31,745 2.8 $88,886 $90,633 

S-205 3 Pneumapress Filter Solids Flow 0.95 $1,575,000 2000 $4,725,000 0.6 $4,594,911 1.05 $4,824,657 $4,824,657 

S-222 1 Hydroclone & Rotary Drum Filter Flow 1.39 $165,000 1998 $165,000 0.39 $187,567 1.4 $262,594 $265,695 

S-227 1 LimeDust Vent Baghouse Flow 4.37 $32,200 1997 $32,200 1 $140,707 1.5 $211,061 $215,211 

T-201 1 Sulfuric Acid Tank Flow 2.00 $5,760 1996 $5,760 0.71 $9,411 1.4 $13,175 $13,603 

T-203 1 Blowdown Tank Flow 1.03 $64,100 1997 $64,100 0.93 $65,987 1.2 $79,184 $80,741 

T-205 1 Hydrolyzate Mixing Tank Flow 0.63 $44,800 1997 $44,800 0.71 $32,237 1.2 $38,684 $39,445 

T-209 1 Overliming Tank Flow 1.62 $71,000 1997 $71,000 0.71 $100,144 1.4 $140,201 $142,958 

T-211 1 Primary Filtrate Tank Flow 1.02 $36,000 2000 $36,000 0.71 $36,414 2.45 $89,214 $89,214 

T-213 1 Wash Filtrate Tank Flow 0.99 $18,000 2000 $18,000 0.71 $17,870 3.68 $65,763 $65,763 

T-220 1 Lime Storage Bin Flow 4.37 $69,200 1997 $69,200 0.46 $136,370 1.3 $177,281 $180,767 

T-224 1 Reacidification Tank Flow 1.63 $147,800 1997 $147,800 0.51 $189,507 1.2 $227,409 $231,881 

T-232 1 Slurrying Tank Flow 1.19 $44,800 1997 $44,800 0.71 $50,839 1.2 $61,007 $62,207 

A200 Subtotal* $14,472,363 $14,636,094 1.83 $26,775,812 $26,843,763 

*Sections are subtotaled and an average "Installation Factor" is back-calculated for the section. Appendix B - Page 2 of 8
Individual Equipment Cost Summary 

Equipment 

Number 

Number 

Required 

Number 

Spares Equipment Name Scaled On 

Size 

Ratio 

(Base/ 

Current) 

Original 

Equip Cost 

(per unit) Base Year 

Total Original 

Equip Cost 

(Req'd & 

Spare) in Base 

Year 

Scaling 

Exponent 

Scaled Cost in 

Base Year 

Installation 

Factor 

Installed Cost in 

Base Year 

Installed Cost 

in 2000$ 

A-300 10 Ethanol Fermentor Agitator None $19,676 1996 $196,760 $196,760 1.2 $236,112 $243,782 

A-301 1 Seed Hold Tank Agitator Flow 0.99 $12,551 1996 $12,551 0.51 $12,492 1.2 $14,990 $15,477 

A-304 2 4th Seed Vessel Agitator Flow 0.99 $11,700 1997 $23,400 0.51 $23,289 1.2 $27,947 $28,497 

A-305 2 5th Seed Vessel Agitator Flow 0.99 $10,340 1996 $20,680 0.51 $20,582 1.2 $24,699 $25,501 

A-306 2 Beer Surge Tank Agitator Flow 1.18 $48,700 1998 $97,400 0.51 $105,852 1.2 $127,023 $128,523 

A-310 10 Saccharification Tank Agitator None $19,676 1996 $196,760 $196,760 1.2 $236,112 $243,782 

F-300 5 Ethanol Fermentor None $493,391 1998 $2,466,955 $2,466,955 1.2 $2,960,346 $2,995,308 

F-301 2 1st Seed Fermentor None $14,700 1997 $29,400 $29,400 2.8 $82,320 $83,939 

F-302 2 2nd Seed Fermentor None $32,600 1997 $65,200 $65,200 2.8 $182,560 $186,150 

F-303 2 3rd Seed Fermentor None $81,100 1997 $162,200 $162,200 2.8 $454,160 $463,090 

F-304 2 4th Seed Fermentor Flow 0.99 $39,500 1997 $79,000 0.93 $78,320 1.2 $93,984 $95,832 

F-305 2 5th Seed Fermentor Flow 0.99 $147,245 1998 $294,490 0.51 $293,097 1.2 $351,717 $355,871 

H-300 5 1 Fermentation Cooler Heat Duty 1.97 $4,000 1997 $24,000 0.78 $40,684 2.1 $85,437 $87,117 

H-301 1 1 Hydrolyzate Heater Area 2.49 $19,040 1996 $38,080 0.68 $70,858 2.1 $148,802 $153,636 

H-302 3 Saccharified Slurry Cooler Area 0.85 $25,409 1998 $76,227 0.78 $67,038 2.1 $140,779 $142,441 

H-304 1 4th Seed Fermentor Coil Heat Duty 1.51 $3,300 1997 $3,300 0.83 $4,658 1.2 $5,589 $5,699 

H-305 1 5th Seed Fermentor Coil Heat Duty 1.51 $18,800 1997 $18,800 0.98 $28,238 1.2 $33,886 $34,552 

H-310 5 1 Fermentation Cooler Heat Duty 0.07 $4,000 1997 $24,000 0.78 $3,054 2.1 $6,413 $6,539 

P-300 5 1 Fermentation Recirc/Transfer Pump Heat Duty 1.97 $8,000 1997 $48,000 0.79 $82,000 2.8 $229,600 $234,115 

P-301 1 1 Seed Hold Transfer Pump Flow 0.99 $22,194 1998 $44,388 0.7 $44,100 1.4 $61,740 $62,469 

P-302 2 Seed Transfer Pump Flow 0.99 $54,088 1998 $108,176 0.7 $107,474 1.4 $150,464 $152,241 

P-306 1 1 Beer Transfer Pump Flow 1.18 $17,300 1997 $34,600 0.79 $39,360 2.8 $110,209 $112,376 

P-310 5 1 Saccharification Recirc/Transfer Pump Heat Duty 0.07 $8,000 1997 $48,000 0.79 $5,954 2.8 $16,671 $16,998 

T-301 1 Seed Hold Tank Flow 0.99 $161,593 1998 $161,593 0.51 $160,829 1.2 $192,995 $195,274 

T-306 1 Beer Storage Tank Flow 1.18 $237,700 1998 $237,700 0.71 $266,897 1.2 $320,276 $324,059 

T-310 5 Saccharification Tank None $493,391 1998 $2,466,955 $2,466,955 1.2 $2,960,346 $2,995,308 

A300 Subtotal* $6,978,615 $7,039,007 1.3 $9,255,176 $9,388,577 

*Sections are subtotaled and an average "Installation Factor" is back-calculated for the section. Appendix B - Page 3 of 8
Individual Equipment Cost Summary 

Equipment 

Number 

Number 

Required 

Number 

Spares Equipment Name Scaled On 

Size 

Ratio 

(Base/ 

Current) 

Original 

Equip Cost 

(per unit) Base Year 

Total Original 

Equip Cost 

(Req'd & 

Spare) in Base 

Year 

Scaling 

Exponent 

Scaled Cost in 

Base Year 

Installation 

Factor 

Installed Cost in 

Base Year 

Installed Cost 

in 2000$ 

A-530 1 Recycled Water Tank Agitator Flow 1.45 $5,963 1998 $5,963 0.51 $7,197 1.3 $9,356 $9,467 

C-501 1 Lignin Wet Cake Screw Flow 0.44 $31,700 1997 $31,700 0.78 $16,837 1.4 $23,571 $24,035 

D-501 1 Beer Column 

Diameter 

Squared 1.13 $478,100 1998 $478,100 0.68 $520,236 2.1 $1,092,496 $1,105,399 

D-502 1 Rectification Column Flow 1.25 $525,800 1996 $525,800 0.68 $613,596 2.1 $1,288,553 $1,330,413 

E-501 2 1st Effect Evaporation Area 1.70 $544,595 1996 $1,089,190 0.68 $1,560,371 2.1 $3,276,779 $3,383,230 

E-502 1 2nd Effect Evaporation Area 1.70 $435,650 1996 $435,650 0.68 $624,111 2.1 $1,310,634 $1,353,211 

E-503 2 3rd Effect Evaporation Area 1.70 $435,650 1996 $871,300 0.68 $1,248,222 2.1 $2,621,267 $2,706,422 

H-501 1 1 Beer Column Reboiler Heat Duty 1.19 $158,374 1996 $316,748 0.68 $357,008 2.1 $749,716 $774,072 

H-502 1 Rectification Column Reboiler Heat Duty 1.18 $29,600 1997 $29,600 0.68 $33,192 2.1 $69,703 $71,074 

H-504 1 Beer Column Condenser Heat Duty 0.37 $29,544 1996 $29,544 0.68 $15,042 2.1 $31,588 $32,614 

H-505 1 Start-up Rect. Column Condenser Heat Duty 1.39 $86,174 1996 $86,174 0.68 $107,911 2.1 $226,613 $233,975 

H-512 1 1 Beer Column Feed Interchanger Area 1.18 $19,040 1996 $38,080 0.68 $42,690 2.1 $89,650 $92,562 

H-517 1 1 Evaporator Condenser Heat Duty 1.75 $121,576 1996 $243,152 0.68 $355,539 2.1 $746,633 $770,888 

M-503 1 Molecular Sieve (9 pieces) Flow 1.20 $2,700,000 1998 $2,700,000 0.7 $3,075,992 1 $3,075,992 $3,112,319 

P-501 1 1 Beer Column Bottoms Pump Flow 1.20 $42,300 1997 $84,600 0.79 $97,723 2.8 $273,623 $279,004 

P-503 1 1 Beer Column Reflux Pump Heat Duty 0.37 $1,357 1998 $2,714 0.79 $1,239 2.8 $3,469 $3,510 

P-504 1 1 Rectification Column Bottoms Pump Flow 1.19 $4,916 1998 $9,832 0.79 $11,316 2.8 $31,685 $32,059 

P-505 1 1 Rectification Column Reflux Pump Heat Duty 1.39 $4,782 1998 $9,564 0.79 $12,418 2.8 $34,772 $35,182 

P-511 2 1 1st Effect Pump Flow 1.09 $19,700 1997 $59,100 0.79 $63,251 2.8 $177,103 $180,585 

P-512 1 1 2nd Effect Pump Flow 1.28 $13,900 1997 $27,800 0.79 $33,843 2.8 $94,759 $96,622 

P-513 2 1 3rd Effect Pump Flow 0.83 $8,000 1997 $24,000 0.79 $20,748 2.8 $58,095 $59,237 

P-514 1 1 Evaporator Condensate Pump Flow 1.69 $12,300 1997 $24,600 0.79 $37,312 2.8 $104,475 $106,529 

P-515 1 Scrubber Bottoms Pump Flow 2.41 $2,793 1998 $2,793 0.79 $5,604 2.8 $15,692 $15,878 

P-530 1 1 Recycled Water Pump Flow 1.45 $10,600 1997 $21,200 0.79 $28,372 2.8 $79,441 $81,003 

S-505 4 Pneumapress Filter Solids Flow 0.85 $1,418,750 2000 $5,675,000 0.6 $5,142,942 1.04 $5,348,660 $5,348,660 

T-503 1 Beer Column Relfux Drum Heat Duty 0.37 $11,900 1997 $11,900 0.93 $4,727 2.1 $9,927 $10,122 

T-505 1 Rectification Column Reflux Drum Heat Duty 1.39 $45,600 1997 $45,600 0.72 $57,855 2.1 $121,496 $123,885 

T-512 1 Vent Scrubber Flow 1.37 $99,000 1998 $99,000 0.78 $126,355 2.1 $265,346 $268,480 

T-514 1 Evaporator Condensate Drum Flow 1.44 $37,200 1998 $37,200 0.93 $52,286 2.1 $109,800 $111,097 

T-530 1 Recycled Water Tank Flow 1.45 $14,515 1998 $14,515 0.745 $19,106 1.4 $26,748 $27,064 

A500 Subtotal* $13,030,419 $14,293,042 1.49 $21,367,640 $21,778,596 

*Sections are subtotaled and an average "Installation Factor" is back-calculated for the section. Appendix B - Page 4 of 8
Individual Equipment Cost Summary 

Equipment 

Number 

Number 

Required 

Number 

Spares Equipment Name Scaled On 

Size 

Ratio 

(Base/ 

Current) 

Original 

Equip Cost 

(per unit) Base Year 

Total Original 

Equip Cost 

(Req'd & 

Spare) in Base 

Year 

Scaling 

Exponent 

Scaled Cost in 

Base Year 

Installation 

Factor 

Installed Cost in 

Base Year 

Installed Cost 

in 2000$ 

A-602 1 Equalization Basin Agitator Flow 0.52 $28,400 1997 $28,400 0.51 $20,286 1.2 $24,343 $24,822 

A-606 1 Anaerobic Agitator Volume 1.03 $30,300 1997 $30,300 0.51 $30,730 1.2 $36,875 $37,601 

A-608 16 Aerobic Lagoon Agitator Power 0.26 $31,250 1998 $500,000 0.51 $253,438 1.4 $354,813 $359,004 

C-614 1 Aerobic Sludge Screw Flow 0.22 $5,700 1997 $5,700 0.78 $1,768 1.4 $2,475 $2,524 

H-602 1 Anaerobic Digestor Feed Cooler Area 0.43 $128,600 1997 $128,600 0.74 $68,759 2.1 $144,393 $147,232 

M-604 1 Nutrient Feed System None $31,400 1998 $31,400 $31,400 2.58 $81,012 $81,969 

M-606 1 Biogas Emergency Flare Flow 0.24 $20,739 1998 $20,739 0.6 $8,877 1.68 $14,914 $15,090 

M-612 1 Filter Precoat System None $3,000 1998 $3,000 $3,000 1.4 $4,200 $4,250 

P-602 1 1 Anaerobic Reactor Feed Pump Flow 0.52 $11,400 1997 $22,800 0.79 $13,539 2.8 $37,910 $38,656 

P-606 1 1 Aerobic Digestor Feed Pump Flow 0.52 $10,700 1997 $21,400 0.79 $12,775 2.8 $35,771 $36,475 

P-608 1 Aerobic Sludge Recycle Pump Flow 0.22 $11,100 1997 $11,100 0.79 $3,356 1.4 $4,699 $4,791 

P-610 1 Aerobic Sludge Pump Flow 0.22 $11,100 1997 $11,100 0.79 $3,356 1.4 $4,699 $4,791 

P-611 1 1 Aerobic Digestion Outlet Pump Flow 0.52 $10,700 1997 $21,400 0.79 $12,707 2.8 $35,579 $36,278 

P-614 1 1 Sludge Filtrate Recycle Pump Flow 0.22 $6,100 1997 $12,200 0.79 $3,681 2.8 $10,306 $10,509 

P-616 1 1 Treated Water Pump Flow 0.53 $10,600 1997 $21,200 0.79 $12,772 2.8 $35,760 $36,463 

S-600 1 Bar Screen Flow 0.52 $117,818 1991 $117,818 0.3 $96,663 1.2 $115,996 $126,526 

S-614 1 Belt Filter Press COD 0.26 $650,223 1998 $650,223 0.72 $248,935 1.8 $448,083 $453,375 

T-602 1 Equalization Basin Flow 0.52 $350,800 1998 $350,800 0.51 $250,578 1.42 $355,821 $360,023 

T-606 1 Anaerobic Digestor Volume 1.03 $881,081 1998 $881,081 0.51 $893,571 1.04 $929,314 $940,289 

T-608 1 Aerobic Digestor Volume 0.52 $635,173 1998 $635,173 1 $330,629 1 $330,629 $334,534 

T-610 1 Clarifier Flow 0.52 $174,385 1998 $174,385 0.51 $124,991 1.96 $244,981 $247,875 

A600 Subtotal* $3,678,819 $2,425,810 1.34 $3,252,573 $3,303,075 

*Sections are subtotaled and an average "Installation Factor" is back-calculated for the section. Appendix B - Page 5 of 8
Individual Equipment Cost Summary 

Equipment 

Number 

Number 

Required 

Number 

Spares Equipment Name Scaled On 

Size 

Ratio 

(Base/ 

Current) 

Original 

Equip Cost 

(per unit) Base Year 

Total Original 

Equip Cost 

(Req'd & 

Spare) in Base 

Year 

Scaling 

Exponent 

Scaled Cost in 

Base Year 

Installation 

Factor 

Installed Cost in 

Base Year 

Installed Cost 

in 2000$ 

A-701 1 Denaturant In-line Mixer Flow 1.32 $1,900 1997 $1,900 0.48 $2,173 1 $2,173 $2,216 

A-720 1 CSL Storage Tank Agitator Flow 0.03 $12,551 1996 $12,551 0.51 $2,143 1.2 $2,572 $2,655 

A-760 1 CSL/DAP Day Tank Agitator Flow 0.93 $12,795 2001 $12,795 0.51 $12,348 1.2 $14,817 $14,582 

C-755 1 DAP Solids Feeder None $3,900 1997 $3,900 $3,900 1.3 $5,070 $5,170 

P-701 2 1 Ethanol Product Pump Flow 1.33 $7,500 1997 $22,500 0.79 $28,200 2.8 $78,959 $80,512 

P-703 1 1 Sulfuric Acid Pump Flow 2.00 $8,000 1997 $16,000 0.79 $27,628 2.8 $77,359 $78,881 

P-704 1 1 Firewater Pump Flow 1.33 $18,400 1997 $36,800 0.79 $46,120 2.8 $129,137 $131,676 

P-710 1 1 Gasoline Pump Flow 1.15 $4,500 1997 $9,000 0.79 $10,041 2.8 $28,114 $28,667 

P-720 1 1 CSL Pump Flow 0.64 $8,800 1997 $17,600 0.79 $12,376 2.8 $34,652 $35,333 

P-750 1 1 Cellulase Pump Flow 1.00 $18,400 1997 $36,800 0.79 $36,803 2.8 $103,049 $105,075 

P-755 1 DAP Unloading Blower Flow 1.06 $47,600 1998 $47,600 0.5 $49,014 1.4 $68,620 $69,431 

P-760 1 1 CSL/DAP Pump Flow 0.64 $8,800 1997 $17,600 0.79 $12,376 2.8 $34,652 $35,333 

S-755 1 DAP Vent Baghouse Flow 0.30 $32,200 1997 $32,200 1 $9,595 1.5 $14,392 $14,675 

T-701 2 Ethanol Product Storage Tank Flow 1.33 $165,800 1997 $331,600 0.51 $383,637 1.4 $537,092 $547,654 

T-703 1 Sulfuric Acid Storage Tank Flow 2.00 $42,500 1997 $42,500 0.51 $60,470 1.2 $72,564 $73,991 

T-704 1 Firewater Storage Tank Flow 1.33 $166,100 1997 $166,100 0.51 $192,175 1.4 $269,045 $274,335 

T-709 1 Propane Storage Tank Flow 1.35 $24,834 2001 $24,834 0.72 $30,825 1.4 $43,155 $42,470 

T-710 1 Gasoline Storage Tank Flow 1.15 $43,500 1997 $43,500 0.51 $46,684 1.4 $65,358 $66,643 

T-720 1 CSL Storage Tank Flow 0.64 $88,100 1997 $88,100 0.79 $61,949 1.4 $86,729 $88,434 

T-750 1 Cellulase Storage Tank Flow 0.74 $125,900 2001 $251,800 0.79 $198,278 1.4 $277,589 $273,186 

T-755 1 DAP Storage Bin Flow 1.06 $33,384 2001 $33,384 0.44 $34,255 1.3 $44,532 $43,826 

T-760 1 CSL/DAP Day Tank Flow 0.93 $30,084 2001 $30,084 0.79 $28,470 1.4 $39,858 $39,226 

A700 Subtotal* $1,216,864 $1,251,396 1.6 $1,975,238 $1,956,244 

*Sections are subtotaled and an average "Installation Factor" is back-calculated for the section. Appendix B - Page 6 of 8
Individual Equipment Cost Summary 

Equipment 

Number 

Number 

Required 

Number 

Spares Equipment Name Scaled On 

Size 

Ratio 

(Base/ 

Current) 

Original 

Equip Cost 

(per unit) Base Year 

Total Original 

Equip Cost 

(Req'd & 

Spare) in Base 

Year 

Scaling 

Exponent 

Scaled Cost in 

Base Year 

Installation 

Factor 

Installed Cost in 

Base Year 

Installed Cost 

in 2000$ 

H-801 1 Burner Combustion Air Preheater Heat Duty 0.49 $1,049,900 1997 $1,049,900 0.6 $687,152 1.5 $1,030,728 $1,050,995 

H-811 1 BFW Preheater Area 0.48 $58,400 1997 $58,400 0.68 $35,477 2.1 $74,502 $75,967 

M-803 1 Fluidized Bed Combustion Reactor Flow 0.54 $24,900,000 1998 $24,900,000 0.75 $15,716,316 1.3 $20,431,211 $20,672,504 

M-804 1 Combustion Gas Baghouse Flow 0.55 $2,536,300 1998 $2,536,300 0.58 $1,784,255 1.5 $2,676,383 $2,707,991 

M-811 1 Turbine/Generator Flow 0.66 $10,000,000 1998 $10,000,000 0.71 $7,422,186 1.5 $11,133,279 $11,264,763 

M-820 1 Hot Process Water Softener System Flow 0.77 $1,381,300 1999 $1,381,300 0.82 $1,114,233 1.3 $1,448,503 $1,461,483 

M-830 1 Hydrazine Addition Pkg. Flow 0.83 $19,000 1994 $19,000 0.6 $16,995 1 $16,995 $18,196 

M-832 1 Ammonia Addition Pkg Flow 0.83 $19,000 1994 $19,000 0.6 $16,995 1 $16,995 $18,196 

M-834 1 Phosphate Addition Pkg. Flow 0.83 $19,000 1994 $19,000 0.6 $16,995 1 $16,995 $18,196 

P-804 2 Condensate Pump Flow 1.94 $7,100 1997 $14,200 0.79 $23,987 2.8 $67,162 $68,483 

P-811 2 Turbine Condensate Pump Flow 0.42 $7,800 1997 $15,600 0.79 $7,819 2.8 $21,892 $22,322 

P-824 2 Deaerator Feed Pump Flow 0.59 $9,500 1997 $19,000 0.79 $12,557 2.8 $35,161 $35,852 

P-826 5 BFW Pump Flow 0.34 $52,501 1998 $262,505 0.79 $111,259 2.8 $311,526 $315,205 

P-828 2 Blowdown Pump Flow 0.86 $5,100 1997 $10,200 0.79 $9,089 2.8 $25,448 $25,949 

P-830 1 Hydrazine Transfer Pump Flow 0.83 $5,500 1997 $5,500 0.79 $4,749 2.8 $13,297 $13,559 

T-804 1 Condensate Collection Tank Flow 0.52 $7,100 1997 $7,100 0.71 $4,472 1.4 $6,261 $6,384 

T-824 1 Condensate Surge Drum Flow 0.78 $49,600 1997 $49,600 0.72 $41,541 1.7 $70,619 $72,008 

T-826 1 Deaerator Flow 0.72 $165,000 1998 $165,000 0.72 $129,664 2.8 $363,059 $367,346 

T-828 1 Blowdown Flash Drum Flow 0.87 $9,200 1997 $9,200 0.72 $8,327 2.8 $23,316 $23,775 

T-830 1 Hydrazine Drum Flow 0.83 $12,400 1997 $12,400 0.93 $10,432 1.7 $17,734 $18,083 

A800 Subtotal* $40,553,205 $27,174,501 1.4 $37,801,069 $38,257,258 

*Sections are subtotaled and an average "Installation Factor" is back-calculated for the section. Appendix B - Page 7 of 8
Individual Equipment Cost Summary 

Equipment 

Number 

Number 

Required 

Number 

Spares Equipment Name Scaled On 

Size 

Ratio 

(Base/ 

Current) 

Original 

Equip Cost 

(per unit) Base Year 

Total Original 

Equip Cost 

(Req'd & 

Spare) in Base 

Year 

Scaling 

Exponent 

Scaled Cost in 

Base Year 

Installation 

Factor 

Installed Cost in 

Base Year 

Installed Cost 

in 2000$ 

M-902 1 Cooling Tower System Heat Duty 0.70 $1,659,000 1998 $1,659,000 0.78 $1,250,136 1.2 $1,500,163 $1,517,880 

M-904 2 1 Plant Air Compressor Flow 1.00 $278,200 2000 $834,600 0.34 $834,598 1.3 $1,084,977 $1,084,977 

M-910 1 CIP System Flow 1.00 $95,000 1995 $95,000 0.6 $95,036 1.2 $114,043 $117,934 

P-902 1 1 Cooling Water Pump Flow 0.67 $332,300 1997 $664,600 0.79 $484,432 2.8 $1,356,409 $1,383,080 

P-912 1 1 Make-up Water Pump Flow 0.76 $10,800 1997 $21,600 0.79 $17,470 2.8 $48,917 $49,879 

P-914 2 1 Process Water Circulating Pump Flow 0.75 $11,100 1997 $33,300 0.79 $26,453 2.8 $74,067 $75,524 

S-904 1 1 Instrument Air Dryer Flow 0.61 $15,498 1999 $30,996 0.6 $23,108 1.3 $30,040 $30,309 

T-902 3 Prehydrolysis Filter Air Receiver Flow 0.89 $17,000 2000 $51,000 0.72 $46,942 1.2 $56,331 $56,331 

T-904 1 Plant Air Receiver Flow 0.61 $13,000 1997 $13,000 0.72 $9,139 1.3 $11,880 $12,114 

T-905 4 Product Recovery Filter Air Receiver Flow 1.04 $17,000 2000 $68,000 0.72 $69,887 1.2 $83,865 $83,865 

T-914 1 Process Water Tank Flow 0.75 $195,500 1997 $195,500 0.51 $168,502 1.4 $235,903 $240,542 

A900 Subtotal* $3,666,596 $3,025,703 1.5 $4,596,596 $4,652,435 

Total Equipment Cost $87,764,599 $73,987,116 1.52 $112,513,533 $113,669,816 

*Sections are subtotaled and an average "Installation Factor" is back-calculated for the section. Appendix B - Page 8 of 8
Appendix C

Chemical Costs and Sources
Chemical Cost and Sources 

Raw Material Cost ($/lb) in 2000 $ Reference 

Clarifier Polymer 1.2500 Harris Group, 2000 

Sulfuric Acid 0.0124 $25/ton, Chemical Marketing Reporter, 2001 

Hydrated Lime 0.0348 $70/ton, Chemical Marketing Reporter, 2001 

Corn Steep Liquor 0.0804 Analysis of CSL market, Ruth, M. Report to Process Engineering Team, 5 June 1998 

Purchased Cellulase Enzyme 0.0552 Set to $0.10/gal ethanol, based on purchased, delivered enzyme 

Diammonium Phosphate 0.0706 $142/ton, Chemical Marketing Reporter, 2001 

Propane 0.0022 $0.734/gal, 1999 average from DOE Energy Information Administration 

Makeup Water 0.0001 $1/1000 gal, Middle of range $0.35-$1.50/1000 gal in Peters/Timmerhaus, pg. 815 

Boiler Chemicals 1.3497 Radian Report, Cases 

Cooing Tower Chems 1.0204 Unknown 

WasteWater Chems 0.1579 Merrick Report Appendix G 

WasteWater Polymer 2.5510 Merrick Report Appendix G 

Gasoline Denaturant 0.0967 $0.555/gal, Analysis of Corn ethanol producers' cost, 1999 average 

Utility 

Solid Disposal 0.0094 $20/ton, Chem Systems Report 1993 

Co-product credit 

Electricity $0.041/kWh Chem Systems Report, 1994 

Appendix C 
Appendix D

Discounted Cash Flow Rate of Return Summary
Discounter Cash Flow Rate of Return Appendix D 

Year -2 -1 0 1 2 3 4 5 6 7 8 9 10 

$15,794,024 $118,455,184 $63,176,098 

Working Capital $9,871,265 

Fixed Capital Investment 

Ethanol Sales $55,407,468 $73,876,624 $73,876,624 $73,876,624 $73,876,624 $73,876,624 $73,876,624 $73,876,624 $73,876,624 $73,876,624 

By-Product Credit $4,824,203 $6,432,270 $6,432,270 $6,432,270 $6,432,270 $6,432,270 $6,432,270 $6,432,270 $6,432,270 $6,432,270 

Total Annual Sales $60,231,670 $80,308,894 $80,308,894 $80,308,894 $80,308,894 $80,308,894 $80,308,894 $80,308,894 $80,308,894 $80,308,894 

Annual Manufacturing Cost 

Raw Materials $20,272,908 $23,169,038 $23,169,038 $23,169,038 $23,169,038 $23,169,038 $23,169,038 $23,169,038 $23,169,038 $23,169,038 

Ion Exchange Resin $0 $0 

Baghouse Bags $349,682 $349,682 

Other Variable Costs $12,932,287 $14,779,757 $14,779,757 $14,779,757 $14,779,757 $14,779,757 $14,779,757 $14,779,757 $14,779,757 $14,779,757 

Fixed Operating Costs $7,540,360 $7,540,360 $7,540,360 $7,540,360 $7,540,360 $7,540,360 $7,540,360 $7,540,360 $7,540,360 $7,540,360 

Total Product Cost $41,095,237 $45,489,155 $45,489,155 $45,489,155 $45,489,155 $45,838,837 $45,489,155 $45,489,155 $45,489,155 $45,489,155 

Annual Depreciation 

General Plant 

DDB $37,422,543 $26,730,388 $19,093,134 $13,637,953 $9,741,395 $6,958,139 $4,970,099 

SL $18,711,271 $15,592,726 $13,365,194 $11,933,209 $11,364,961 $11,364,961 $11,364,961 

Remaining Value $93,556,357 $66,825,969 $47,732,835 $34,094,882 $24,353,487 $17,395,348 $12,425,249 

Actual $37,422,543 $26,730,388 $19,093,134 $13,637,953 $11,364,961 $11,364,961 $11,364,961 

Steam Plant 

DDB $4,983,480 $4,609,719 $4,263,990 $3,944,191 $3,648,377 $3,374,749 $3,121,642 $2,887,519 $2,670,955 $2,470,634 

SL $3,322,320 $3,234,891 $3,158,511 $3,093,483 $3,040,314 $2,999,777 $2,972,993 $2,961,558 $2,961,558 $2,961,558 

Remaining Value $61,462,926 $56,853,206 $52,589,216 $48,645,025 $44,996,648 $41,621,899 $38,500,257 $35,612,738 $32,941,782 $30,471,149 

Actual $4,983,480 $4,609,719 $4,263,990 $3,944,191 $3,648,377 $3,374,749 $3,121,642 $2,961,558 $2,961,558 $2,961,558 

Net Revenue ($23,269,590) $3,479,632 $11,462,614 $17,237,595 $19,806,401 $19,730,348 $20,333,136 $31,858,181 $31,858,181 $31,858,181 

Losses Forward ($23,269,590) ($19,789,958) ($8,327,344) $0 $0 $0 $0 $0 $0 

Taxable Income ($23,269,590) ($19,789,958) ($8,327,344) $8,910,250 $19,806,401 $19,730,348 $20,333,136 $31,858,181 $31,858,181 $31,858,181 

Income Tax $0 $0 $0 $3,474,998 $7,724,496 $7,694,836 $7,929,923 $12,424,690 $12,424,690 $12,424,690 

Annual Cash Income $19,136,433 $34,819,739 $34,819,739 $31,344,741 $27,095,242 $26,775,222 $26,889,816 $22,395,048 $22,395,048 $22,395,048 

Discount Factor 1.21 1.1 1 0.909090909 0.826446281 0.751314801 0.683013455 0.620921323 0.56447393 0.513158118 0.46650738 0.424097618 0.385543289 

Annual Present Value $220,991,534 $17,396,757 $28,776,644 $26,160,585 $21,408,880 $16,824,014 $15,113,915 $13,798,727 $10,447,455 $9,497,687 $8,634,261 

Total Capital Investment + Interest $19,110,770 $130,300,702 $73,047,363 

Net Present Worth $0 

If income taxable income < 0, tax = $0

Loan Interest subtracted from taxable income.

Loan payment subtracted from annual cash income

Interest on construction loan added to investment

NPV of Income Tax $60,794,932 $0 $0 $0 $2,373,470 $4,796,305 $4,343,534 $4,069,304 $5,796,210 $5,269,282 $4,790,256 

NPV of Ethanol Income $612,163,202 $50,370,425 $61,055,061 $55,504,601 $50,458,728 $45,871,571 $41,701,428 $37,910,389 $34,463,990 $31,330,900 $28,482,637 
Discounter Cash Flow Rate of Return Appendix D 

Year 11 12 13 14 15 16 17 18 19 20

Fixed Capital Investment

Working Capital ($9,871,265)

Ethanol Sales $73,876,624 $73,876,624 $73,876,624 $73,876,624 $73,876,624 $73,876,624 $73,876,624 $73,876,624 $73,876,624 $73,876,624 

By-Product Credit $6,432,270 $6,432,270 $6,432,270 $6,432,270 $6,432,270 $6,432,270 $6,432,270 $6,432,270 $6,432,270 $6,432,270 

Total Annual Sales $80,308,894 $80,308,894 $80,308,894 $80,308,894 $80,308,894 $80,308,894 $80,308,894 $80,308,894 $80,308,894 $80,308,894 

Annual Manufacturing Cost 

Raw Materials $23,169,038 $23,169,038 $23,169,038 $23,169,038 $23,169,038 $23,169,038 $23,169,038 $23,169,038 $23,169,038 $23,169,038 

Ion Exchange Resin $0 $0 

Baghouse Bags $349,682 $349,682 

Other Variable Costs $14,779,757 $14,779,757 $14,779,757 $14,779,757 $14,779,757 $14,779,757 $14,779,757 $14,779,757 $14,779,757 $14,779,757 

Fixed Operating Costs $7,540,360 $7,540,360 $7,540,360 $7,540,360 $7,540,360 $7,540,360 $7,540,360 $7,540,360 $7,540,360 $7,540,360 

Total Product Cost $45,838,837 $45,489,155 $45,489,155 $45,489,155 $45,489,155 $45,838,837 $45,489,155 $45,489,155 $45,489,155 $45,489,155 

Annual Depreciation 

General Plant 

DDB 

SL 

Remaining Value 

Actual 

Steam Plant 

DDB $2,285,336 $2,113,936 $1,955,391 $1,808,736 $1,673,081 $1,547,600 $1,431,530 $1,324,165 $1,224,853 $1,132,989 

SL $2,961,558 $2,961,558 $2,961,558 $2,961,558 $2,961,558 $2,961,558 $2,961,558 $2,961,558 $2,961,558 $2,961,558 

Remaining Value $28,185,812 $26,071,877 $24,116,486 $22,307,749 $20,634,668 $19,087,068 $17,655,538 $16,331,373 $15,106,520 $13,973,531 

Actual $2,961,558 $2,961,558 $2,961,558 $2,961,558 $2,961,558 $2,961,558 $2,961,558 $2,961,558 $2,961,558 $2,961,558 

Net Revenue $31,508,499 $31,858,181 $31,858,181 $31,858,181 $31,858,181 $31,508,499 $31,858,181 $31,858,181 $31,858,181 $31,858,181 

Losses Forward $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 

Taxable Income $31,508,499 $31,858,181 $31,858,181 $31,858,181 $31,858,181 $31,508,499 $31,858,181 $31,858,181 $31,858,181 $31,858,181 

Income Tax $12,288,315 $12,424,690 $12,424,690 $12,424,690 $12,424,690 $12,288,315 $12,424,690 $12,424,690 $12,424,690 $12,424,690 

Annual Cash Income $22,181,743 $22,395,048 $22,395,048 $22,395,048 $22,395,048 $22,181,743 $22,395,048 $22,395,048 $22,395,048 $22,395,048 

Discount Factor 0.350493899 0.318630818 0.28966438 0.263331254 0.239392049 0.217629136 0.197844669 0.17985879 0.163507991 0.148643628 

Annual Present Value $7,774,565 $7,135,753 $6,487,048 $5,897,316 $5,361,197 $4,827,393 $4,430,741 $4,027,946 $3,661,769 $3,328,881 

Total Capital Investment + Interest ($1,467,301) 

Net Present Worth 

NPV of Income Tax $4,306,979 $3,958,889 $3,598,990 $3,271,809 $2,974,372 $2,674,295 $2,458,159 $2,234,690 $2,031,536 $1,846,851 

NPV of Ethanol Income $25,893,306 $23,539,369 $21,399,426 $19,454,024 $17,685,476 $16,077,706 $14,616,096 $13,287,360 $12,079,418 $10,981,289
Ethanol Production Process Engineering Analysis

Corn Stover Design Report Case, process P110: 2010 plant start-up 

Dilute Acid Prehydrolysis with Saccharification and Co-Fermentation 

All Values in 2000$ 

Minimum Ethanol Selling Price $1.07 

Ethanol Production (MM Gal. / Year) 69.3 Ethanol at 68°F 

Ethanol Yield (Gal / Dry US Ton Feedstock) 89.7 

Feedstock Cost $/Dry US Ton $30 

Internal Rate of Return (After-Tax) 10% 

Equity Percent of Total Investment 100% 

Capital Costs 

Feed Handling $7,500,000 

Pretreatment $19,000,000 

Neutralization/Conditioning $7,800,000 

Saccharification & Fermentation $9,400,000 

Distillation and Solids Recovery $21,800,000 

Wastewater Treatment $3,300,000 

Storage $2,000,000 

Boiler/Turbogenerator $38,300,000 

Utilities $4,700,000 

Total Installed Equipment Cost $113,700,000 

Added Costs $83,700,000 

(% of TPI) 42% 

Total Project Investment $197,400,000 

Loan Rate N/A 

Term (years) N/A 

Capital Charge Factor 0.176 

Denatured Fuel Prod. (MMgal / yr) 72.5 

Denatured Fuel Min. Sales Price $1.04 

Denaturant Cost ($/gal denaturant) $0.555 

Maximum Yields (100% of Theoretical) 

Ethanol Production (MM Gal/yr) 87.0 

Theoretical Yield (Gal/ton) 112.7 

Current Yield (Actual/Theoretical) 80% 

Operating Costs (cents/gal ethanol) 

Feedstock

Biomass to Boiler

CSL

Cellulase

Other Raw Materials

Waste Disposal

Electricity

Fixed Costs

Capital Depreciation

Average Income Tax

Average Return on Investment

33.4 

0.0 

2.8 

10.1 

5.5 

2.9 

-9.3 

10.9 

14.3 

10.6 

25.4 

106.8 

Operating Costs ($/yr) 

Feedstock

Biomass to Boiler

CSL

Cellulase

Other Raw Matl. Costs

Waste Disposal

Electricity

Fixed Costs

Capital Depreciation

Average Income Tax

Average Return on Investment

Excess Electricity (KWH/gal)

Plant Electricity Use (KWH/gal)

Plant Steam Use (kg steam/gal)

Boiler Feed -- LHV (Btu/lb)

Boiler Feed -- Water Fraction

$23,200,000 

$0 

$1,900,000 

$7,000,000 

$3,800,000 

$2,000,000 

-$6,400,000 

$7,500,000 

$9,900,000 

$7,300,000 

$17,600,000 

$73,800,000 

2.28 

1.42 

16.7 

2,870 

0.518 

Appendix D 
Variable and Fixed Operating Costs 

Production 

Rate (MM 

gal/yr) 69.27 24,686 

Feedstock Dry 

Tons/yr 772168 

gal/ton 90 

Hours per 

Year 8,406 

Variable Operating Costs 

Costing 

Code Raw Material 

Stream 

No. kg/hr lb/hr 

Quoted 

Price 

(cents / 

ton) 

Year of 

Price 

Quote 

2000 Cost 

(cents / 

ton) 

2000 Cost 

($/lb) $/hour 

MM$/yr 

(2000) 

Cents/Gallon 

Ethanol (2000) 

F-1 Feedstock STRM010 98,039 216,176 2550 2000 2550.00 0.0128 2756.25 23.17 33.45 

F-1 Feedstock STRM084 0 0 2550 2000 2550.00 0.0128 0.00 0.00 0.00 

S-11 Clarifier Polymer STRM010 28 63 250000 2000 250000.00 1.2500 78.24 0.66 0.95 

R-5 Sulfuric Acid STRM071 3,288 7,251 2500 2001 2485.99 0.0124 90.13 0.76 1.09 

R-4 Hydrated Lime STRM074 2,395 5,280 7000 2001 6960.77 0.0348 183.77 1.54 2.23 

R-3 Corn Steep Liquor STRM073 1,306 2,879 15000 1998 16087.17 0.0804 231.57 1.95 2.81 

R-7 Purchased Cellulase STRM075 6,824 15,046 10823 1999 11044.07 0.0552 830.86 6.98 10.08 

R-8 Ammonium Phosphate STRM075 163 360 14200 2001 14120.42 0.0706 25.42 0.21 0.31 

S-12 Propane 3 20 45 436 1999 444.90 0.0022 0.10 0.00 0.001 

S-8 Makeup Water STRM090 189,649 411,562 24 1990 23.30 0.0001 48.67 0.40 0.58 

S-1 Boiler Chemicals STRM092 1.0 2 280000 1991 269932.90 1.3497 2.98 0.03 0.04 

S-2 Cooling Tower Chems STRM092 1.9 4 200000 1999 204081.02 1.0204 4.28 0.04 0.05 

S-4 WasteWater Chems STRM063 57.9 128 30956 1999 31587.66 0.1579 20.18 0.17 0.24 

S-5 WasteWater Polymer STRM063 0.2 0.43 500000 1999 510202.54 2.5510 1.10 0.01 0.01 

Subtotal 4272.73 35.92 51.85 

Waste Streams 

W-2 Disposal of Steam 809 STRM080 4,492 9,906 1820 1993 1872.61 0.0094 92.75 0.78 1.13 

W-3 Disposal of Stream 229 STRM022 7,217 15,913 1820 1993 1872.61 0.0094 148.99 1.25 1.81 

Subtotal 241.74 2.03 2.93 

By-Product Credits KW $/KW $/kWh 

P-1 Electricity WKNET 18,747 na 0.040 1999 0.041 765.20 6.43 9.29 

Subtotal 765.20 6.43 9.29 

Total Variable Operating 

Costs 3,749.29 31.52 45.50 

Fixed Operating Costs 

Plant Manager 80000 1 80,000 

Plant Engineer 65000 1 65,000 

Maintenance Supr 60000 1 60,000 

Lab Manager 50000 1 50,000 

Shift Supervisor 37000 5 185,000 

Lab Technician 25000 2 50,000 

Maintenance Tech 28000 8 224,000 

Shift Operators 25000 20 500,001 

Yard Employees 20000 32 640,001 

General Manager 100000 1 100,000 

Clerks & Secretaries 20000 5 100,000 

Total Salaries 2,054,002 2.15 3.11 

Overhead/Maint 60% 

of Labor & 

Supervison 1,292,976 1.29 1.87 

Maintenance 2% 

Equipment 

Cost 2,273,396 2.27 3.28 

Insurance & Taxes 1.5% 

of Total 

Installed Cost 1,819,029 1.82 2.63 

Total Fixed Operating Costs 7.54 10.89 

Total Cash Cost 39.06 56.38 

Appendix D 
Appendix E

Process Parameters
Process Area Process Parameter Model Value 

Minimum Ethanol Selling Price ($/gal) $1.07 

Feedstock Feedstock Flow (dry metric ton/day) 2000 

Feedstock Cost ($/dry US ton) $30 

Cellulose Fraction 37.4% 

Xylan Fraction 21.1% 

Arabinan Fraction 2.9% 

Mannan Fraction 1.6% 

Galactan Fraction 2.0% 

Lignin Fraction 18.0% 

Pretreatment Reactor Residence Time 2 min 

Acid Concentration 1.1% 

Temperature 190°C 

Xylan to Xylose Yield 90% 

Mannan to Mannose Yield 90% 

Galactan to Galactose Yield 90% 

Arabinan to Arabinose Yield 90% 

Type of Conditioning Overliming 

Saccharification Cellulase Purchase Price ($/gal total ethanol) $0.10 

Cellulase Purchase Price ($/gal cellulose-derived ethanol) $0.17 

Residence Time 1.5 days 

Temperature 65°C 

Cellulose to Glucose Yield 90% 

Co-Fermentation Residence Time 1.5 days 

Temperature 41°C 

Glucose to Ethanol Yield 95% 

Xylose to Ethanol Yield 85% 

Arabinose to Ethanol Yield 85% 

Mannose to Ethanol Yield 85% 

Galactose to Ethanol Yield 85% 

Contamination Loss 3% 

Overall Cellulose to Ethanol Yield 85.5% 

Utilities Electricity Credit ($/kWh) $0.041 

On-line Time (hr/yr) 8406 

Model: I0203I 
Appendix F

Process Flow Diagrams

Note: Larger format (11” x 17”) versions of these Process Flow Diagrams are available upon request from 

Kelly_Ibsen@nrel.gov 
COMPONENT UNITS 101 102 103 104 105 107

Total Flow kg/hr 98,039 43,017 11,400 1,009 128,676 28

Insoluble Solids% 77.4% 0.0% 0.0% 0.0% 59.0% 0.0%

Soluble Solids% 7.6% 0.1% 0.1% 0.1% 5.8% 0.0%

TemperatureC 20 74 74 74 45 20

Pressure atm 1.00 3.00 1.00 1.00 1.00 1.00

Vapor Fraction 0.00 0.00 0.00 0.00 0.00 0.00

Ethanol kg/hr 3181 22

Water kg/hr 14,706 42,546 11,275 970 45,007

Glucose (SS) kg/hr

Xylose (SS) kg/hr 0 0 0 0

Arabinose (SS) kg/hr0

Other Sugars (SS) kg/hr

Cellobiose (SS) kg/hr

Glucose Oligomers (SS) kg/hr

Xylose Oligomers (SS) kg/hr0000

Other Oligomers (SS) kg/hr

Corn Steep Liquor (SS) kg/hr 58 15 1 41

Others (Soluble Solids) kg/hr 7,417 7,417

Acetic Acid kg/hr 325 867 232

Sulfuric Acid kg/hr 0 0 0 0

Furfural kg/hr 48 13 1 34

HMF kg/hr7205

Carbon Dioxide kg/hr

Methane kg/hr

Oxygen kg/hr

Nitrogen kg/hr

Others kg/hr 2 0 28 1 28

Cellulose (IS) kg/hr 31,187 31,187

Xylan (IS) kg/hr 17,570 17,570

Arabinan (IS) kg/hr 2,435 2,435

Other Sugar Polymers (IS) kg/hr 2,919 2,919

Cellulase (IS) kg/hr

Biomass (IS) kg/hr

Zymo (IS) kg/hr

Lignin (IS) kg/hr 15,002 15,002

Gypsum (IS) kg/hr

Ca(OH)2 (IS) kg/hr

Others (Insoluble Solids) kg/hr 6,804 6,804

Enthalpy Flow (millions) Kcal/hr -170.1 -160.0 -42.4 -3.8 -284.0 -0.1

Average Density g/ml 1.4709 0.9442 0.9443 0.9443 1.3433 0.9983

Work Stream No. kW Work Stream No. kW

WC101 55.93 WP102 74.09

WC102 11.18 WP103 2.94

WC103 2.80 WP104 37.05

WC104 11.18 WP105 1.18

WM104 83.90 WS101 5.59

WM105 1118.56 WS102 4.19

WM107 25.00 WS103 0.00

WP101 37.06

I0203I.xls

Eq. No. Equipment Name Req.Spare Equipment Type Mat Const.

C-101 Bale Transport Conveyor2 BELT CS

C-102 Bale Unwrapping Conveyor2 BELT CS

C-103 Belt Press Discharge Conveyor1 BELT CS

C-104 Shredder Feed Conveyor4 BELT CS

M-101 Truck Scales2 TRUCK-SCALE CONCRETE

M-102 Truck Unloading Forklift41 LOADER

M-103 Bale Moving Forklift4 LOADER

M-104 Corn Stover Wash Table2 A283

M-105 Shredder4 ALLOY STEEL

M-106 Concrete Feedstock-Storage Slab1 CONCRETE-SLAB CONCRETE

M-107 Polymer Feed System1 MISCELLANEOUS CS

P-101 Wash Table Pump 2 1 CENTRIFUGAL CS; RUBBER

P-102 Wash Water Pump21 CENTRIFUGAL CS; SS316

P-103 Clarifier Underflow Pump11 RECIPROCATING CS; RUBBER

P-104 Clarified Water Pump11 CENTRIFUGAL CS; SS316

P-105 Belt Press Sump Pump11 SLURRY CS

S-101 Clarifier Thickener1 CS

S-102 Belt Press1 FILTER-PRESS 304SS; FILTER

S-103 Magnetic Separator1 MAGNET

T-101 Wash Water Tank1 VERTICAL-VESSEL CS

T-102 Clarifier Thickener Tank1 CLARIFER CEMENT
Heat Stream No. MM kcal/hr Work Stream No. kW

QH201 -0.19 WC201 37.08

QH201B -22.31 WM202 699.80

QH244 3.64 WP201 1.16

COMPONENT UNITS 105 211 212 214 215 216 217 218 220 233 501 502 520 520A 710

Total Flow kg/hr 128,676 99,344 2,104 101,447 11,507 37,234 278,865 53,152 225,713 1,185 449,353 449,353 53,152 53,152 3,288

Insoluble Solids% 59.0% 0.0% 0.0% 0.0% 0.0% 0.0% 17.2% 0.0% 21.3% 0.0% 5.0% 5.0% 0.0% 0.0% 0.0%

Soluble Solids% 5.8% 0.1% 0.0% 0.1% 0.0% 0.0% 12.6% 0.1% 15.6% 0.0% 3.6% 3.6% 0.1% 0.1% 0.0%

TemperatureC 45 74 20 74 164 268 190 101 101 20 95 41 30 100 20

Pressure atm 1.00 3.00 3.40 4.00 4.42 13.00 12.05 1.00 1.00 3.40 4.00 0.90 1.00 1.00 1.00

Vapor Fraction 0.00 0.00 0.00 0.00 1.00 1.00 0.00 1.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Ethanol kg/hr 22 71 71 93 73 20 24,825 24,825 73 73

Water kg/hr 45,007 98,256 98,256 11,507 37,234 189,218 52,244 136,974 374,828 374,828 52,244 52,244

Glucose (SS) kg/hr 2,426 2,426 82 82

Xylose (SS) kg/hr000 17,9690 17,969 909 90900

Arabinose (SS) kg/hr00 2,4900 2,490 217 21700

Other Sugars (SS) kg/hr 2,919 2,919 254 254

Cellobiose (SS) kg/hr 230 230 360 360

Glucose Oligomers (SS) kg/hr 291 291 1,853 1,853

Xylose Oligomers (SS) kg/hr000 5000 500 646 64600

Other Oligomers (SS) kg/hr 750 750 969 969

Corn Steep Liquor (SS) kg/hr 41 133 133 174 48 126 1,459 1,459 48 48

Others (Soluble Solids) kg/hr 7,417 7,417 7,417 9,581 9,581

Acetic Acid kg/hr 232 751 751 3,426 268 3,158 5,258 5,258 268 268

Sulfuric Acid kg/hr 0 0 2,104 2,104 2,1040 2,104 1,185 154 154 0 0 3,288

Furfural kg/hr 34 111 111 727 449 278 576 576 449 449

HMF kg/hr5 17 17 114 70 43 90 90 70 70

Carbon Dioxide kg/hr 440 440

Methane kg/hr

Oxygen kg/hr00

Nitrogen kg/hr00

Others kg/hr 1 44 5 0 5 4,276 4,276 0 0

Cellulose (IS) kg/hr 31,187 28,567 28,567 1,365 1,365

Xylan (IS) kg/hr 17,570 439 439 439 439

Arabinan (IS) kg/hr 2,435 61 61 61 61

Other Sugar Polymers (IS) kg/hr 2,919 73 73 73 73

Cellulase (IS) kg/hr 650 650

Biomass (IS) kg/hr00

Zymo (IS) kg/hr 1,088 1,088

Lignin (IS) kg/hr 15,002 14,251 14,251 14,252 14,252

Gypsum (IS) kg/hr 28 28

Ca(OH)2 (IS) kg/hr

Others (Insoluble Solids) kg/hr 6,804 4,620 4,620 4,620 4,620

Enthalpy Flow (millions) Kcal/hr -284.0 -369.5 -4.1 -373.6 -36.2 -115.2 -809.0 -166.8 -642.2 -2.3 -1488.8 -1510.9 -198.6 -195.0 -6.4

Average Density g/ml 1.3433 0.9442 1.8166 0.9489 0.0022 0.0053 0.9973 0.0006 1.1246 1.8166 0.9585 0.9520 0.9903 0.9195 1.8166

Eq. No. Equipment Name Req.Spare Equipment Type Mat Const.

A-201 In-line Sulfuric Acid Mixer1 SS304

C-201 Hydrolyzate Screw Conveyor1 SCREW SS316

H-201 Beer Column Feed Economizer 2 1 SHELL-TUBE 304SS

H-244 Waste Vapor Condensor21 SHELL-TUBE 304SS

M-202 Prehydrolysis/Screw Feeder/Reactor3 VESSEL W/ PADDLESALLOY 825-CLAD; SS316L

P-201 Sulfuric Acid Pump11 CENTRIFUGAL SS304

T-201 Sulfuric Acid Tank1 VERTICAL-VESSEL PLASTIC

T-203 Blowdown Tank1 VERTICAL-VESSEL SS316

I0203I.xls
Heat Stream No. MM kcal/hr Work Stream No. kW

QH200 2.44 WC202 26.76

QH205 0.13 WP205 159.88

WP211 14.27

WP213 221.34

WP224 83.85

WS205 96.02

WT205 15.42

WT232 30.24

COMPONENT UNITS 219 220 221 230 232 240 250 252 253 255 256 259 260 261 262

Total Flow kg/hr 207,096 225,713 138,563 265,125 428,764 268,762 428,764 130,913 76,182 87,456 130,199 4,687 5,094 4,894 200

Insoluble Solids% 0.2% 21.3% 0.2% 0.0% 11.2% 0.1% 11.2% 0.2% 0.2% 54.9% 0.0% 0.0% 0.0% 0.0% 0.0%

Soluble Solids% 1.7% 15.6% 19.7% 13.1% 9.0% 13.0% 9.0% 1.7% 1.7% 2.7% 5.9% 0.0% 0.0% 0.0% 0.0%

TemperatureC 46 101 101 53 51 50 51 46 46 50 55 40 50 38 38

Pressure atm 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 9.51 1.00 1.00 1.00

Vapor Fraction 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1.00 1.00 1.00 0.00

Ethanol kg/hr 28 20 15 36 47 36 47 18 101 21000

Water kg/hr 200,466 136,974 106,622 225,312 335,811 226,537 335,811 126,722 73,744 36,755 119,915 404 205 199

Glucose (SS) kg/hr 19 2,426 1,888 2,263 2,432 2,275 2,432 127 163 387

Xylose (SS) kg/hr 210 17,969 13,987 16,806 18,087 16,898 18,087 132 77 1,204 2,910

Arabinose (SS) kg/hr 50 2,490 1,938 2,342 2,528 2,355 2,528 32 18 167 417

Other Sugars (SS) kg/hr 59 2,919 2,272 2,745 2,962 2,760 2,962 37 22 196 488

Cellobiose (SS) kg/hr 83 230 179 266 312 267 312 52 31 15 88

Glucose Oligomers (SS) kg/hr 427 291 227 539 716 542 716 270 157 20 315

Xylose Oligomers (SS) kg/hr 149 500 389 558 646 561 646 94 55 34 171

Other Oligomers (SS) kg/hr 223 750 584 837 969 841 969 141 82 50 257

Corn Steep Liquor (SS) kg/hr 145 126 98 208 270 209 270 91 53 8 111 0 0 0

Others (Soluble Solids) kg/hr 2,209 7,417 5,773 8,271 9,581 8,316 9,581 1,397 813 497 2,543

Acetic Acid kg/hr 1,341 3,158 2,458 3,773 4,477 3,794 4,477 848 493 210 1,336111

Sulfuric Acid kg/hr 36 2,104 1,637 154 1,985 154 22 13 141 34800

Furfural kg/hr 301 278 217 448 576 450 576 190 111 17 233210

HMF kg/hr 47 43 34 70 90 70 90 30 173 36000

Carbon Dioxide kg/hr 29 18 29 19 29 19 11 19

Methane kg/hr

Oxygen kg/hr000000000 984 984 9840

Nitrogen kg/hr000000000 3,703 3,702 3,7020

Others kg/hr 95254 603 954 607 954 602 3500 603000

Cellulose (IS) kg/hr7 28,567 1431 28,432 143 28,43243 28,429

Xylan (IS) kg/hr 2 439 2 0 439 2 439 1 1 438

Arabinan (IS) kg/hr 0 61 0 0 61 0 61 0 0 61

Other Sugar Polymers (IS) kg/hr 0 73 0 0 73 0 73 0 0 73

Cellulase (IS) kg/hr 81 81 81 51 30 51

Biomass (IS) kg/hr000000

Zymo (IS) kg/hr 136 136 136 86 50 86

Lignin (IS) kg/hr 71 14,251 71 0 14,252 71 14,252 45 26 14,225

Gypsum (IS) kg/hr0 28 28 28 0 0 0

Ca(OH)2 (IS) kg/hr

Others (Insoluble Solids) kg/hr 23 4,620 230 4,620 23 4,620 158 4,612

Enthalpy Flow (millions) Kcal/hr -755.7 -642.2 -425.6 -874.2 -1389.4 -883.9 -1389.4 -477.7 -278.0 -237.2 -455.8 0.0 -1.3 -0.6 -0.8

Average Density g/ml 0.9793 1.1246 0.9974 1.0158 1.0720 1.0207 1.0720 0.9793 0.9793 1.3246 0.9855 0.0106 0.0010 0.0011 0.9808

Eq. No. Equipment Name Req.Spare Equipment Type Mat Const.

A-205 Hydrolyzate Mix Tank Agitator1 FIXED-PROP SS

A-232 Reslurrying Tank Agitator1 FIXED-PROP SS

C-202 Hydrolysate Washed Solids Belt Conveyor 1 BELT CS

H-200 Hydrolyzate Cooler1 SHELL-TUBE 304SS;CS

H-205 Pneumapress Vent Condensor1 SHELL-TUBE CS

P-205 Pneumapress Feed Pump21 CENTRIFUGAL SS316

P-211 Primary Filtrate Pump 1 1 CENTRIFUGAL SS316

P-213 Wash Filtrate Pump 1 1 CENTRIFUGAL SS316

P-224 Saccharification 21 ROTARY-LOBE 304SS

S-205 Pneumapress Filter3 PNEUMAPRESS SS316

T-205 Hydrolyzate Mixing Tank1 FLAT-BTM-STORAGESS304

T-211 Primary Filtrate Tank1 VERTICAL-VESSEL SS316

T-213 Wash Filtrate Tank1 VERTICAL-VESSEL SS316

T-232 Slurrying Tank1 FLAT-BTM-STORAGESS304

I0203I.xls

Feed Pump
Heat Stream No. MM kcal/hr Work Stream No. kW

WC225 0.84

WP209 57.59

WP222 57.01

WP223 28.74

WP239 38.64

WS222 30.34

WT209 25.97

WT224 104.41

COMPONENT UNITS 227 228 229 230 233 239 240

Total Flow kg/hr 2,395 271,157 7,217 265,125 1,185 272,342 268,762

Insoluble Solids% 100.0% 1.7% 80.0% 0.0% 0.0% 2.1% 0.1%

Soluble Solids% 0.0% 12.9% 2.6% 13.1% 0.0% 12.9% 13.0%

TemperatureC 50 53 53 20 53 50

Pressure atm 1.00 1.00 1.00 1.00 3.40 1.00 1.00

Vapor Fraction 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Ethanol kg/hr 36 0 36 36 36

Water kg/hr 226,537 1,225 225,312 226,537 226,537

Glucose (SS) kg/hr 2,275 12 2,263 2,275 2,275

Xylose (SS) kg/hr 16,898 91 16,806 16,898 16,898

Arabinose (SS) kg/hr 2,355 13 2,342 2,355 2,355

Other Sugars (SS) kg/hr 2,760 15 2,745 2,760 2,760

Cellobiose (SS) kg/hr 267 1 266 267 267

Glucose Oligomers (SS) kg/hr 5423 539 542 542

Xylose Oligomers (SS) kg/hr 561 3 558 561 561

Other Oligomers (SS) kg/hr 8415 837 841 841

Corn Steep Liquor (SS) kg/hr 2091 208 209 209

Others (Soluble Solids) kg/hr 8,316 45 8,271 8,316 8,316

Acetic Acid kg/hr 3,794 21 3,773 3,794 3,794

Sulfuric Acid kg/hr 1,185 1,985

Furfural kg/hr 4502 448 450 450

HMF kg/hr 700 70 70 70

Carbon Dioxide kg/hr 19 0 18 19 19

Methane kg/hr

Oxygen kg/hr00000

Nitrogen kg/hr 0 0 0 0 0

Others kg/hr 6073 603 607 607

Cellulose (IS) kg/hr 143 142 1 143 143

Xylan (IS) kg/hr22022

Arabinan (IS) kg/hr00000

Other Sugar Polymers (IS) kg/hr 0 0 0 0 0

Cellulase (IS) kg/hr

Biomass (IS) kg/hr

Zymo (IS) kg/hr

Lignin (IS) kg/hr 71 710 71 71

Gypsum (IS) kg/hr 3,485 5,537 28 5,565

Ca(OH)2 (IS) kg/hr 2,395 895

Others (Insoluble Solids) kg/hr 23 230 23 23

Enthalpy Flow (millions) Kcal/hr -7.6 -892.6 -20.7 -874.2 -2.3 -894.9 -883.9

Average Density g/ml 2.3430 1.0397 2.0146 1.0158 1.8166 1.0422 1.0207

Eq. No. Equipment Name Req. Spare Equipment Type Mat Const.

A-209 Overliming Tank Agitator1 FIXED-PROP SS

A-224 Reacidification Tank Agitator1 FIXED-PROP SS

C-225 Lime Solids Feeder1 ROTARY-VALVE A285C

P-209 Overlimed Hydrolyzate Pump11 CENTRIFUGAL 304SS

P-222 Filtered Hydrolyzate Pump 1 1 CENTRIFUGAL 304SS

P-223 Lime Unloading Blower1 CENTRIFUGAL C.S.

P-239 Reacidified Liquor Pump11 CENTRIFUGAL SS304

S-222 Hydroclone & Rotary Drum Filter1 ROTARY-DRUM EPOXY LINED

S-227 LimeDust Vent Baghouse1 FABRIC-FILTER A285C;POLYESTER

T-209 Overliming Tank1 VERTICAL-VESSEL SS304

T-220 Lime Storage Bin1 LIVE-BTM-BIN CS

T-224 Reacidification Tank1 FLAT-BTM-STORAGESS304

I0203I.xls
Heat Stream No. MM kcal/hr Work Stream No. kW

QF301 0.21 WP301 16.95

WP302 16.95

WT301 23.40

WT304 11.70

WT305 39.00

COMPONENT UNITS 303 304 304C 310 310A

Total Flow kg/hr 43,559 41,391 2,415 28 219

Insoluble Solids% 5.0% 5.7% 0.0% 0.0% 0.0%

Soluble Solids% 15.7% 4.6% 0.0% 0.0% 100.0%

TemperatureC 41 41 41 20 20

Pressure atm 1.00 1.00 1.00 1.00 1.00

Vapor Fraction 0.00 0.00 1.00 0.00 0.00

Ethanol kg/hr5 2,335 70

Water kg/hr 33,919 33,881 76

Glucose (SS) kg/hr 3,119 103

Xylose (SS) kg/hr 1,809 156

Arabinose (SS) kg/hr 253 32

Other Sugars (SS) kg/hr 296 37

Cellobiose (SS) kg/hr 36 36

Glucose Oligomers (SS) kg/hr 185 185

Xylose Oligomers (SS) kg/hr 65 65

Other Oligomers (SS) kg/hr 97 97

Corn Steep Liquor (SS) kg/hr 27 224 0 219

Others (Soluble Solids) kg/hr 958 958

Acetic Acid kg/hr 448 527 1

Sulfuric Acid kg/hr 15 150

Furfural kg/hr 58 571

HMF kg/hr 9 9 0

Carbon Dioxide kg/hr 3 40 2,235

Methane kg/hr

Oxygen kg/hr00 32

Nitrogen kg/hr000

Others kg/hr 95 292 0 28

Cellulose (IS) kg/hr 136 136

Xylan (IS) kg/hr 44 44

Arabinan (IS) kg/hr66

Other Sugar Polymers (IS) kg/hr77

Cellulase (IS) kg/hr 65 65

Biomass (IS) kg/hr 0 0

Zymo (IS) kg/hr 14 193

Lignin (IS) kg/hr 1,425 1,425

Gypsum (IS) kg/hr33

Ca(OH)2 (IS) kg/hr

Others (Insoluble Solids) kg/hr 462 462

Enthalpy Flow (millions) Kcal/hr -141.7 -137.7 -5.1 -0.1 -0.8

Average Density g/ml 1.0754 1.0176 0.0016 1.0096 0.9983

Eq. No. Equipment Name Req.Spare Equipment Type Mat Const.

A-301 Seed Hold Tank Agitator1 FIXED-PROP SS304

A-304 4th Seed Vessel Agitator2 FIXED-PROP SS

A-305 5th Seed Vessel Agitator2 FIXED-PROP SS

F-301 1st Seed Fermentor2 VERTICAL-VESSEL SS304

F-302 2nd Seed Fermentor2 VERTICAL-VESSEL SS304

F-303 3rd Seed Fermentor2 VERTICAL-VESSEL SS304

F-304 4th Seed Fermentor2 FLAT-BTM-STORAGESS304

F-305 5th Seed Fermentor2 FLAT-BTM-STORAGESS304

H-304 4th Seed Fermentor Coil1 IMMERSED-COIL SS

H-305 5th Seed Fermentor Coil1 IMMERSED-COIL SS

P-301 Seed Hold Transfer Pump 1 1 ROTARY-LOBE SS304

P-302 Seed Transfer Pump2 ROTARY-LOBE SS304

T-301 Seed Hold Tank1 FLAT-BTM-STORAGESS304

I0203I.xls
Heat Stream No. MM kcal/hr Work Stream No. kW

QF300A 0.09 WP300 345.20

QF300 2.40 WP306 119.04

QH301 -4.89 WP310 122.90

QH302 8.49 WT300 438.73

WT306 113.64

WT310 445.89

COMPONENT UNITS 232 301A 301B 302 303 304 306 308 311 311A 312 502 551 590 591

Total Flow kg/hr 428,764 428,764 435,588 392,029 43,559 41,391 412,222 22,420 136 1,087 6,824 449,353 37,130 9,490 9,490

Insoluble Solids% 11.2% 11.2% 5.0% 5.0% 5.0% 5.7% 5.5% 0.0% 0.0% 0.0% 8.3% 5.0% 0.0% 0.0% 0.0%

Soluble Solids% 9.0% 9.0% 15.7% 15.7% 15.7% 4.6% 4.0% 0.0% 0.0% 100.0% 0.0% 3.6% 0.0% 0.0% 0.0%

TemperatureC 51 65 65 41 41 41 41 41 20 20 20 41 39 164 148

Pressure atm 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 0.90 0.90 4.42 4.42

Vapor Fraction 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.00 0.00 1.00 0.00

Ethanol kg/hr 47 47 47 43 5 2,335 24,032 668 24,825 793

Water kg/hr 335,811 335,811 339,188 305,269 33,919 33,881 338,544 710 6,255 374,828 36,284 9,490 9,490

Glucose (SS) kg/hr 2,432 2,432 31,193 28,074 3,119 103 82 82

Xylose (SS) kg/hr 18,087 18,087 18,087 16,279 1,809 156 909 909

Arabinose (SS) kg/hr 2,528 2,528 2,528 2,275 253 32 217 217

Other Sugars (SS) kg/hr 2,962 2,962 2,962 2,666 296 37 254 254

Cellobiose (SS) kg/hr 312 312 360 324 36 36 360 360

Glucose Oligomers (SS) kg/hr 716 716 1,853 1,668 185 185 1,853 1,853

Xylose Oligomers (SS) kg/hr 646 646 646 581 65 65 646 646

Other Oligomers (SS) kg/hr 969 969 969 872 97 97 969 969

Corn Steep Liquor (SS) kg/hr 270 270 270 243 27 224 1,4563 1,087 1,4594

Others (Soluble Solids) kg/hr 9,581 9,581 9,581 8,623 958 958 9,581 9,581

Acetic Acid kg/hr 4,477 4,477 4,477 4,029 448 527 5,2516 5,2587

Sulfuric Acid kg/hr 154 154 154 139 15 15 1540 1540

Furfural kg/hr 576 576 576 518 58 57 5687 5768

HMF kg/hr 90 90 90 8199 891 901

Carbon Dioxide kg/hr 29 29 29 263 40 406 20,799 440 34

Methane kg/hr

Oxygen kg/hr0000000 22600

Nitrogen kg/hr0000000000

Others kg/hr 954 954 954 859 95 292 4,2760 136 4,2760

Cellulose (IS) kg/hr 28,432 28,432 1,365 1,228 136 136 1,365 1,365

Xylan (IS) kg/hr 439 439 439 395 44 44 439 439

Arabinan (IS) kg/hr 61 61 61 55 6 6 61 61

Other Sugar Polymers (IS) kg/hr 73 73 73 66 7 7 73 73

Cellulase (IS) kg/hr 81 81 650 585 65 65 650 568 650

Biomass (IS) kg/hr 0 0 0 0 0 0 00

Zymo (IS) kg/hr 136 136 136 122 14 193 1,088 1,088

Lignin (IS) kg/hr 14,252 14,252 14,252 12,827 1,425 1,425 14,252 14,252

Gypsum (IS) kg/hr 28 28 28 25 3 3 28 28

Ca(OH)2 (IS) kg/hr

Others (Insoluble Solids) kg/hr 4,620 4,620 4,620 4,158 462 462 4,620 4,620

Enthalpy Flow (millions) Kcal/hr -1389.4 -1384.5 -1408.7 -1275.5 -141.7 -137.7 -1372.7 -47.5 -0.4 -4.1 -24.2 -1510.9 -138.2 -29.8 -34.7

Average Density g/ml 1.072 1.059 1.052 1.075 1.075 1.018 1.015 0.002 1.010 0.998 1.040 0.952 0.975 0.002 0.865

Eq. No. Equipment Name Req.Spare Equipment Type Mat Const.

A-300 Ethanol Fermentor Agitator 10 FIXED-PROP SS304

A-306 Beer Surge Tank Agitator2 FIXED-PROP SS304

A-310 Saccharification Tank Agitator 10 FIXED-PROP SS304

F-300 Ethanol Fermentor5 FLAT-BTM-STORAGESS304

H-300 Fermentation Cooler51 PLATE-FRAME SS304

H-301 Hydrolyzate Heater 1 1 PLATE-FRAME SS

H-302 Saccharified Slurry Cooler3 PLATE-FRAME SS304

H-310 Fermentation Cooler 5 1 PLATE-FRAME SS304

P-300 Fermentation Recirc/Transfer Pump51 CENTRIFUGAL SS304

P-306 Beer Transfer Pump11 CENTRIFUGAL SS304

P-310 Saccharification Recirc/Transfer Pump 5 1 CENTRIFUGAL SS304

T-306 Beer Storage Tank1 FLAT-BTM-STORAGESS304

T-310 Saccharification Tank5 FLAT-BTM-STORAGESS304

I0203I.xls
I0203I.xls

Eq. No. Equipment Name Req. SpareEquipment Type Mat Const.

D-501 Beer Column1 DISTILLATION SS304

H-501 Beer Column Reboiler 1 1 SHELL-TUBE SS304;CS

H-504 Beer Column Condenser1 SHELL-TUBE SS304;CS

H-512 Beer Column Feed Interchanger11 PLATE-FRAME SS

P-501 Beer Column Bottoms Pump 1 1 CENTRIFUGAL SS

P-503 Beer Column Reflux Pump 1 1 CENTRIFUGAL SS

T-503 Beer Column Relfux Drum1 HORIZONTAL-VESSELSS304

COMPONENT UNITS 501 506 508 510 518 518A 594 595

Total Flow kg/hr 449,353 449,353 491 62,329 386,533 386,533 65,505 65,505

Insoluble Solids% 5.0% 5.0% 0.0% 0.0% 5.8% 5.8% 0.0% 0.0%

Soluble Solids% 3.6% 3.6% 0.0% 0.2% 4.2% 4.2% 0.0% 0.0%

TemperatureC 95 100 60 113 123 117 164 148

Pressure atm 4.00 4.76 1.86 1.91 2.10 2.10 4.42 4.42

Vapor Fraction 0.00 0.00 1.00 1.00 0.00 0.00 1.00 0.00

Ethanol kg/hr 24,825 24,825 60 24,583 182 182

Water kg/hr 374,828 374,828 20 36,990 337,819 337,819 65,505 65,505

Glucose (SS) kg/hr 82 82 0 0 82 82

Xylose (SS) kg/hr 909 909 0 0 909 909

Arabinose (SS) kg/hr 217 21700 217 217

Other Sugars (SS) kg/hr 254 25400 254 254

Cellobiose (SS) kg/hr 360 36000 360 360

Glucose Oligomers (SS) kg/hr 1,853 1,85300 1,853 1,853

Xylose Oligomers (SS) kg/hr 646 64600 646 646

Other Oligomers (SS) kg/hr 969 96900 969 969

Corn Steep Liquor (SS) kg/hr 1,459 1,4590 145 1,314 1,314

Others (Soluble Solids) kg/hr 9,581 9,581 0 0 9,581 9,581

Acetic Acid kg/hr 5,258 5,258 0 259 4,998 4,998

Sulfuric Acid kg/hr 154 154 0 0 154 154

Furfural kg/hr 576 576 0 278 298 298

HMF kg/hr 90 90 0 43 46 46

Carbon Dioxide kg/hr 440 440 411 29

Methane kg/hr

Oxygen kg/hr000000

Nitrogen kg/hr0000

Others kg/hr 4,276 4,27601 4,275 4,275

Cellulose (IS) kg/hr 1,365 1,365 1,365 1,365

Xylan (IS) kg/hr 439 439 439 439

Arabinan (IS) kg/hr 61 61 61 61

Other Sugar Polymers (IS) kg/hr 73 73 73 73

Cellulase (IS) kg/hr 650 650 650 650

Biomass (IS) kg/hr 0 0 0 0

Zymo (IS) kg/hr 1,088 1,088 1,088 1,088

Lignin (IS) kg/hr 14,252 14,252 14,252 14,252

Gypsum (IS) kg/hr 28 28 28 28

Ca(OH)2 (IS) kg/hr

Others (Insoluble Solids) kg/hr 4,620 4,620 4,620 4,620

Enthalpy Flow (millions) Kcal/hr -1488.8 -1486.6 -1.0 -147.3 -1304.9 -1307.1 -205.9 -239.7

Average Density g/ml 0.9585 0.9534 0.0029 0.0014 0.9513 0.9570 0.0022 0.8653

Heat Stream No. MM kcal/hr Work Stream No. kW

QCD501 0.37 WP501 312.41

QH512 -2.18 WP503 0.51

QRD501 -33.76
I0203I.xls

Heat Stream No. MM kcal/hr Work Stream No. kW

QRD502 -4.21 WP504 9.31

WP505 12.77

WP515 6.10

COMPONENT UNITS 304C 308 508 510 511 516 521 523 524 550 551 592 593

Total Flow kg/hr 2,415 22,420 491 62,329 33,232 37,643 8,546 25,325 35,912 24,107 37,130 8,164 8,164

Insoluble Solids% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0%

Soluble Solids% 0.0% 0.0% 0.0% 0.2% 0.0% 0.4% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0%

TemperatureC 41 41 60 113 92 121 70 41 26 29 39 164 148

Pressure atm 1.00 1.00 1.86 1.91 1.70 4.29 1.53 1.00 1.00 0.90 0.90 4.42 4.42

Vapor Fraction 1.00 1.00 1.00 1.00 1.00 0.00 0.00 1.00 0.00 1.00 0.00 1.00 0.00

Ethanol kg/hr 70 668 60 24,583 30,740 19 6,176 7974 793

Water kg/hr 76 710 20 36,990 2,492 36,868 2,370 806 35,912 434 36,284 8,164 8,164

Glucose (SS) kg/hr000

Xylose (SS) kg/hr 0 000

Arabinose (SS) kg/hr 0 000

Other Sugars (SS) kg/hr000

Cellobiose (SS) kg/hr 0 00

Glucose Oligomers (SS) kg/hr000

Xylose Oligomers (SS) kg/hr0000

Other Oligomers (SS) kg/hr 0 00

Corn Steep Liquor (SS) kg/hr030 145 145404

Others (Soluble Solids) kg/hr000

Acetic Acid kg/hr 1 6 0 259 2597 0 7

Sulfuric Acid kg/hr00000000

Furfural kg/hr170 278 278808

HMF kg/hr 0 1 0 43 431 0 1

Carbon Dioxide kg/hr 2,235 20,799 411 29 29 23,444 23,410 34

Methane kg/hr

Oxygen kg/hr 32 226 0 00 258 258 0

Nitrogen kg/hr00000000

Others kg/hr 0 0 0 110 0 0

Cellulose (IS) kg/hr

Xylan (IS) kg/hr

Arabinan (IS) kg/hr

Other Sugar Polymers (IS) kg/hr

Cellulase (IS) kg/hr

Biomass (IS) kg/hr

Zymo (IS) kg/hr

Lignin (IS) kg/hr

Gypsum (IS) kg/hr

Ca(OH)2 (IS) kg/hr

Others (Insoluble Solids) kg/hr

Enthalpy Flow (millions) Kcal/hr -5.1 -47.5 -1.0 -147.3 -44.6 -137.3 -17.5 -53.6 -136.0 -51.4 -138.2 -25.7 -29.9

Average Density g/ml 0.0016 0.0016 0.0029 0.0014 0.0023 0.8964 0.7943 0.0016 0.9925 0.0016 0.9750 0.0022 0.8653

Eq. No. Equipment Name Req.Spare Equipment Type Mat Const.

D-502 Rectification Column1 DISTILLATION SS

H-502 Rectification Column Reboiler1 SHELL-TUBE SS304;CS

H-505 Start-up Rect. Column Condenser1 SHELL-TUBE SS304;CS

P-504 Rectification Column Bottoms Pump11 CENTRIFUGAL SS

P-505 Rectification Column Reflux Pump11 CENTRIFUGAL SS

P-515 Scrubber Bottoms Pump1 CENTRIFUGAL SS

T-505 Rectification Column Reflux Drum1 HORIZONTAL-VESSELSS304

T-512 Vent Scrubber1 ABSORBER SS304;PLASTIC
I0203I.xls

Eq. No. Equipment Name Req.Spare Equipment Type Mat Const.

M-503 Molecular Sieve (9 pieces)1 PACKAGE SS

COMPONENT UNITS 511 511C 515 515A 517 519 521 522 596 597

Total Flow kg/hr 33,232 33,232 24,686 8,546 8,546 24,686 8,546 8,546 621 621

Insoluble Solids% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0%

Soluble Solids% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0%

TemperatureC 92 116 38 116 35 92 70 70 164 148

Pressure atm 1.70 1.70 1.00 1.70 0.14 1.44 1.53 1.53 4.42 4.42

Vapor Fraction 1.00 1.00 0.00 1.00 0.00 1.00 0.00 0.00 1.00 0.00

Ethanol kg/hr 30,740 30,740 24,564 6,176 6,176 24,564 6,176 6,176

Water kg/hr 2,492 2,492 122 2,370 2,370 122 2,370 2,370 621 621

Glucose (SS) kg/hr

Xylose (SS) kg/hr

Arabinose (SS) kg/hr

Other Sugars (SS) kg/hr

Cellobiose (SS) kg/hr

Glucose Oligomers (SS) kg/hr

Xylose Oligomers (SS) kg/hr

Other Oligomers (SS) kg/hr

Corn Steep Liquor (SS) kg/hr

Others (Soluble Solids) kg/hr

Acetic Acid kg/hr

Sulfuric Acid kg/hr

Furfural kg/hr

HMF kg/hr

Carbon Dioxide kg/hr

Methane kg/hr

Oxygen kg/hr

Nitrogen kg/hr

Others kg/hr

Cellulose (IS) kg/hr

Xylan (IS) kg/hr

Arabinan (IS) kg/hr

Other Sugar Polymers (IS) kg/hr

Cellulase (IS) kg/hr

Biomass (IS) kg/hr

Zymo (IS) kg/hr

Lignin (IS) kg/hr

Gypsum (IS) kg/hr

Ca(OH)2 (IS) kg/hr

Others (Insoluble Solids) kg/hr

Enthalpy Flow (millions) Kcal/hr -44.6 -44.3 -35.6 -14.8 -17.8 -29.7 -17.5 -17.5 -2.0 -2.3

Average Density g/ml 0.0023 0.0022 0.7753 0.0017 0.8308 0.0022 0.7943 0.7943 0.0022 0.8653

Heat Stream No. MM kcal/hr Work Stream No. kW

QH503 2.96 WM503 171.59

QH506 -0.32

QH507 0.24

QH509 5.86
I0203I.xls

COMPONENT UNITS 102 211 251 518A 525 526 527 528 529 530 531 532 533 534A 535 580 860

Total Flow kg/hr 43,017 99,344 71,466 386,533 303,646 82,887 82,887 116,868 77,752 77,752 39,922 76,946 76,946 237,585 23,759 194,620 4,858

Insoluble Solids% 0.0% 0.0% 0.0% 5.8% 7.4% 0.0% 0.0% 0.8% 0.0% 0.0% 2.4% 0.0% 0.0% 0.0% 0.0% 0.5% 0.0%

Soluble Solids% 0.1% 0.1% 0.1% 4.2% 5.2% 0.4% 0.4% 8.8% 0.0% 0.0% 25.8% 0.0% 0.0% 0.1% 0.1% 5.3% 0.0%

TemperatureC 74 74 74 117 87 87 87 71 71 71 64 64 64 74 74 40 115

Pressure atm 3.00 3.00 3.00 2.10 0.60 0.60 0.61 0.31 0.31 0.32 0.21 0.21 0.23 2.00 1.00 3.20 1.68

Vapor Fraction 0.00 0.00 0.00 0.00 0.00 1.00 0.00 0.00 1.00 0.00 0.00 1.00 0.00 0.00 0.00 0.00 0.97

Ethanol kg/hr 31 71 51 182 39 143 143 3 24 24 0 2 2 170 17 27

Water kg/hr 42,546 98,256 70,684 337,819 255,932 81,887 81,887 99,813 77,243 77,243 23,957 75,856 75,856 234,985 23,499 177,056 4,858

Glucose (SS) kg/hr 82 82 57 57 57

Xylose (SS) kg/hr 0 0 0 909 909 0 0 629 0 0 629 0 0 0 0 629

Arabinose (SS) kg/hr 0 0 0 217 217 0 0 150 150 0 0 150

Other Sugars (SS) kg/hr 254 254 176 176 176

Cellobiose (SS) kg/hr 360 360 249 249 249

Glucose Oligomers (SS) kg/hr 1,853 1,853 1,282 1,282 1,282

Xylose Oligomers (SS) kg/hr 0 0 0 646 646 0 0 447 0 0 447 0 0 0 0 447

Other Oligomers (SS) kg/hr 969 969 670 670 670

Corn Steep Liquor (SS) kg/hr 58 133 96 1,314 996 319 319 319 32

Others (Soluble Solids) kg/hr 9,581 9,581 6,628 6,628 6,628

Acetic Acid kg/hr 325 751 540 4,998 4,689 309 309 2,827 418 418 1,757 1,070 1,070 1,796 180 3,244

Sulfuric Acid kg/hr 0 0 0 154 154 0 0 107 0 0 107 0 0 0 0 107

Furfural kg/hr 48 111 80 298 100 197 197 13 56 56 2 12 12 265 27 69

HMF kg/hr7 17 12 46 16 31 31299022 414 11

Carbon Dioxide kg/hr

Methane kg/hr

Oxygen kg/hr0

Nitrogen kg/hr

Others kg/hr243 4,275 4,27322 2,85222 2,8475591 2,854

Cellulose (IS) kg/hr 1,365 1,365 20 20 20

Xylan (IS) kg/hr 439 439777

Arabinan (IS) kg/hr 61 61111

Other Sugar Polymers (IS) kg/hr 73 73111

Cellulase (IS) kg/hr 650 650 244 244 244

Biomass (IS) kg/hr00000

Zymo (IS) kg/hr 1,088 1,088 408 408 408

Lignin (IS) kg/hr 14,252 14,252 214 214 214

Gypsum (IS) kg/hr 28 28000

Ca(OH)2 (IS) kg/hr

Others (Insoluble Solids) kg/hr 4,620 4,620 69 69 69

Enthalpy Flow (millions) Kcal/hr -160.0 -369.5 -265.8 -1307.1 -1018.2 -262.3 -307.3 -374.4 -247.0 -290.0 -88.4 -243.9 -286.5 -883.7 -88.4 -665.5 -15.5

Average Density g/ml 0.944 0.944 0.944 0.957 1.003 0.000 0.932 0.983 0.000 0.948 1.085 0.000 0.954 0.944 0.944 0.999 0.001

861

4,858

0.0%

0.0%

115

1.68

0.00

4,858

-18.0

0.947

Stream No. MM kcal/hr Stream No. kW

QCD502 24.58 WP511 198.53

QE501A2 2.49 WP512 55.37

QE502B 44.05 WP513 23.68

QE503B 42.11 WP514 40.33

QH517 42.58

Eq. No. Equipment Name Req.Spare Equipment Type Mat Const.

E-501 1st Effect Evaporation2 SHELL-TUBE SS316

E-502 2nd Effect Evaporation1 SHELL-TUBE SS316

E-503 3rd Effect Evaporation2 SHELL-TUBE SS316

H-517 Evaporator Condenser11 SHELL-TUBE SS304;CS

P-511 1st Effect Pump 2 1 CENTRIFUGAL SS

P-512 2nd Effect Pump11 CENTRIFUGAL SS

P-513 3rd Effect Pump 2 1 CENTRIFUGAL SS

P-514 Evaporator Condensate Pump11 CENTRIFUGAL SS304

T-514 Evaporator Condensate Drum1 HORIZONTAL-VESSELSS304
I0203I.xls

COMPONENT UNITS 219 516 525 559 571 572 573 574 560 580

Total Flow kg/hr 207,096 37,643 303,646 5,921 44,075 259,493 64,873 104,579 5,999 194,620

Insoluble Solids% 0.2% 0.0% 7.4% 0.0% 48.3% 0.5% 0.5% 0.0% 0.0% 0.5%

Soluble Solids% 1.7% 0.4% 5.2% 0.0% 4.9% 5.3% 5.3% 0.0% 0.1% 5.3%

TemperatureC 46 121 87 40 38 40 40 20 38 40

Pressure atm 1.00 4.29 0.60 9.51 3.20 3.20 3.20 1.00 3.20 3.20

Vapor Fraction 0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.00 1.00 0.00

Ethanol kg/hr 28 19 393 3690 27

Water kg/hr 200,466 36,868 255,932 19,783 236,075 59,019 104,579 74 177,056

Glucose (SS) kg/hr 19 82 6 76 19 57

Xylose (SS) kg/hr 2100 909 70 838 210 629

Arabinose (SS) kg/hr 500 217 17 200 50 150

Other Sugars (SS) kg/hr 59 254 20 235 59 176

Cellobiose (SS) kg/hr 83 360 28 332 83 249

Glucose Oligomers (SS) kg/hr 427 1,853 144 1,709 427 1,282

Xylose Oligomers (SS) kg/hr 1490 646 50 596 149 447

Other Oligomers (SS) kg/hr 223 969 75 894 223 670

Corn Steep Liquor (SS) kg/hr 145 145 996 9924

Others (Soluble Solids) kg/hr 2,209 9,581 743 8,838 2,209 6,628

Acetic Acid kg/hr 1,341 259 4,689 363 4,326 1,0811 3,244

Sulfuric Acid kg/hr 360 154 12 142 360 107

Furfural kg/hr 301 278 1008 93 230 69

HMF kg/hr 47 43 16 1 14 4 0 11

Carbon Dioxide kg/hr 29 29

Methane kg/hr

Oxygen kg/hr00 1,2430 1,243

Nitrogen kg/hr00 4,6781 4,677

Others kg/hr 952 1 4,273 468 3,805 9510 2,854

Cellulose (IS) kg/hr7 1,365 1,337 27 7 20

Xylan (IS) kg/hr2 439 430927

Arabinan (IS) kg/hr0 61 60101

Other Sugar Polymers (IS) kg/hr0 73 72101

Cellulase (IS) kg/hr 81 650 325 325 81 244

Biomass (IS) kg/hr00 0 0 00

Zymo (IS) kg/hr 136 1,088 544 544 136 408

Lignin (IS) kg/hr 71 14,252 13,967 285 71 214

Gypsum (IS) kg/hr0 28 27100

Ca(OH)2 (IS) kg/hr

Others (Insoluble Solids) kg/hr 23 4,620 4,528 92 23 69

Enthalpy Flow (millions) Kcal/hr -755.7 -137.3 -1018.2 0.0 -136.2 -887.3 -221.8 -396.6 -0.2 -665.5

Average Density g/ml 0.9793 0.8964 1.0034 0.0106 1.3326 0.9990 0.9990 0.9983 0.0036 0.9990

Eq. No. Equipment Name Req.Spare Equipment Type Mat Const.

A-530 Recycled Water Tank Agitator1 FIXED-PROP CS

C-501 Lignin Wet Cake Screw1 SCREW CS

P-530 Recycled Water Pump 1 1 CENTRIFUGAL CS

S-505 Pneumapress Filter4 PNEUMAPRESS SS316

T-530 Recycled Water Tank1 FLAT-BTM-STORAGECS

Heat Stream No. MM kcal/hr Work Stream No. kW

WC501 28.16

WP530 59.41

WS505 113.91

WT530 6.83
I0203I.xls

COMPONENT UNITS 262 520 535 612 613 615 618 630 821 944

Total Flow kg/hr 200 53,152 23,759 97,264 97,264 625 96,697 58 5,715 14,439

Insoluble Solids% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0%

Soluble Solids% 0.0% 0.1% 0.1% 0.1% 0.1% 0.0% 0.1% 0.0% 0.0% 0.0%

TemperatureC 38 30 74 59 35 35 35 20 309 28

Pressure atm 1.00 1.00 1.00 2.00 2.00 1.00 1.00 1.00 96.26 1.00

Vapor Fraction 0.00 0.00 0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.00

Ethanol kg/hr0 73 17 90 9006

Water kg/hr 199 52,244 23,499 96,094 96,094 28 96,414 5,715 14,439

Glucose (SS) kg/hr

Xylose (SS) kg/hr00000

Arabinose (SS) kg/hr00000

Other Sugars (SS) kg/hr

Cellobiose (SS) kg/hr

Glucose Oligomers (SS) kg/hr

Xylose Oligomers (SS) kg/hr0000

Other Oligomers (SS) kg/hr

Corn Steep Liquor (SS) kg/hr0 48 32 80 80 0 80

Others (Soluble Solids) kg/hr

Acetic Acid kg/hr 1 268 180 449 449 0 31

Sulfuric Acid kg/hr00000

Furfural kg/hr0 449 27 476 4760 33

HMF kg/hr0 70 4 74 74 0 5

Carbon Dioxide kg/hr 273 25

Methane kg/hr 3241

Oxygen kg/hr00000

Nitrogen kg/hr00000

Others kg/hr 0 0 1 1 1 0 58 58

Cellulose (IS) kg/hr

Xylan (IS) kg/hr

Arabinan (IS) kg/hr

Other Sugar Polymers (IS) kg/hr

Cellulase (IS) kg/hr

Biomass (IS) kg/hr 43

Zymo (IS) kg/hr

Lignin (IS) kg/hr

Gypsum (IS) kg/hr

Ca(OH)2 (IS) kg/hr

Others (Insoluble Solids) kg/hr

Enthalpy Flow (millions) Kcal/hr -0.8 -198.6 -88.4 -362.3 -364.6 -1.0 -365.0 -0.2 -19.9 -54.6

Average Density g/ml 0.9808 0.9903 0.9442 0.9604 0.9846 0.0009 0.9841 0.9983 0.6925 0.9906

Heat Stream No. MM kcal/hr Work Stream No. kW

QH602 2.26 WM604 4.14

WP602 22.57

WP606 22.45

WS600 0.42

WT602 14.37

WT606 31.06

Eq. No. Equipment Name Req.Spare Equipment Type Mat Const.

A-602 Equalization Basin Agitator1 FIXED-PROP SS

A-606 Anaerobic Agitator1 FIXED-PROP SS

H-602 Anaerobic Digestor Feed Cooler1 SHELL-TUBE SS316;CS

M-604 Nutrient Feed System1 PACKAGE CS

M-606 Biogas Emergency Flare1 MISCELLANEOUS SS

P-602 Anaerobic Reactor Feed Pump 1 1 CENTRIFUGAL CS

P-606 Aerobic Digestor Feed Pump11 CENTRIFUGAL CS

S-600 Bar Screen1 SCREEN CS

T-602 Equalization Basin1 FLAT-BTM-STORAGECONCRETE

T-606 Anaerobic Digestor1 FLAT-BTM-STORAGEEPOXY-LINED
I0203I.xls

COMPONENT UNITS 618 620 621 623 624 625 626 627 631

Total Flow kg/hr 96,697 40,204 97,095 218 95,805 1,290 39,531 1,0720

Insoluble Solids% 0.0% 0.0% 0.1% 30.0% 0.0% 5.1% 0.0% 0.0% 0.0%

Soluble Solids% 0.1% 0.0% 0.1% 0.1% 0.1% 0.1% 0.0% 0.1% 0.0%

TemperatureC 35 21 21 21 21 21 20 21 20

Pressure atm 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00

Vapor Fraction 0.00 1.00 0.00 0.00 0.00 0.00 1.00 0.00 0.00

Ethanol kg/hr 6 0 1 0 1 00

Water kg/hr 96,414 627 96,881 152 95,658 1,222 1,070

Glucose (SS) kg/hr

Xylose (SS) kg/hr000000

Arabinose (SS) kg/hr0

Other Sugars (SS) kg/hr

Cellobiose (SS) kg/hr

Glucose Oligomers (SS) kg/hr

Xylose Oligomers (SS) kg/hr

Other Oligomers (SS) kg/hr

Corn Steep Liquor (SS) kg/hr 80 1 80 0 79 11

Others (Soluble Solids) kg/hr

Acetic Acid kg/hr 31030300

Sulfuric Acid kg/hr

Furfural kg/hr 33030300

HMF kg/hr5000000

Carbon Dioxide kg/hr 25 112 0 0 0 00

Methane kg/hr 1 1 0 0 0 00

Oxygen kg/hr0 8,235 1 0 1 0 8,3020

Nitrogen kg/hr0 31,228 1 0 1 0 31,2300

Others kg/hr 580 580 58110

Cellulose (IS) kg/hr

Xylan (IS) kg/hr

Arabinan (IS) kg/hr

Other Sugar Polymers (IS) kg/hr

Cellulase (IS) kg/hr

Biomass (IS) kg/hr 43 65 65 65

Zymo (IS) kg/hr

Lignin (IS) kg/hr

Gypsum (IS) kg/hr

Ca(OH)2 (IS) kg/hr

Others (Insoluble Solids) kg/hr

Enthalpy Flow (millions) Kcal/hr -365.0 -2.3 -367.9 -0.6 -363.2 -4.7 0.0 -4.1 0.0

Average Density g/ml 0.9841 0.0012 0.9976 1.1481 0.9973 1.0228 0.0012 0.9973 0.9983

Eq. No. Equipment Name Req.Spare Equipment Type Mat Const.

A-608 Aerobic Lagoon Agitator 16 SURFACE-AERATORCS

C-614 Aerobic Sludge Screw1 SCREW CS

M-612 Filter Precoat System1 MISCELLANEOUS CS

P-608 Aerobic Sludge Recycle Pump1 SLURRY SS316

P-610 Aerobic Sludge Pump1 SLURRY SS316

P-611 Aerobic Digestion Outlet Pump 1 1 CENTRIFUGAL CS

P-614 Sludge Filtrate Recycle Pump11 CENTRIFUGAL CS

P-616 Treated Water Pump11 CENTRIFUGAL CS

S-614 Belt Filter Press1 FILTER-PRESS 304SS;BUNA N

T-608 Aerobic Digestor1 LINED-PIT POLYMER LINED

T-610 Clarifier1 CLARIFIER CONCRETE

Heat Stream No. MM kcal/hr Work Stream No. kW

WC614 1.25

WM612 0.90

WP608 0.29

WP610 0.17

WP611 22.24

WP614 0.25

WP616 21.95

WS614 11.64

WT608 159.77

WT610 2.07
COMPONENT UNITS 310 310A 311 311A 312 515 701 703 710 713 723 735 750 755

Total Flow kg/hr 28 219 136 1,087 6,824 24,686 1,019 25,705 3,288 9,080 20 1,306 6,824 163

Insoluble Solids % 0.0% 0.0% 0.0% 0.0% 8.3% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 8.3% 0.0%

Soluble Solids % 0.0% 100.0% 0.0% 100.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 100.0% 0.0% 0.0%

Temperature C 20 20 20 20 20 38 20 20 20 20 20 20 20 2 0

Pressure atm 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00

Vapor Fraction 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1.00 0.00 0.00 0.00

Ethanol kg/hr 24,564 24,564

Water kg/hr 6,255 122 122 9,080 6,255

Glucose (SS) kg/hr

Xylose (SS) kg/hr

Arabinose (SS) kg/hr

Other Sugars (SS) kg/hr

Cellobiose (SS) kg/hr

Glucose Oligomers (SS) kg/hr

Xylose Oligomers (SS) kg/hr

Other Oligomers (SS) kg/hr

Corn Steep Liquor (SS) kg/hr 219 1,087 1,306

Others (Soluble Solids) kg/hr

Acetic Acid kg/hr

Sulfuric Acid kg/hr 3,288

Furfural kg/hr

HMF kg/hr

Carbon Dioxide kg/hr

Methane kg/hr

Oxygen kg/hr

Nitrogen kg/hr

Others kg/hr 28 136 1,019 1,019 20 163

Cellulose (IS) kg/hr

Xylan (IS) kg/hr

Arabinan (IS) kg/hr

Other Sugar Polymers (IS) kg/hr

Cellulase (IS) kg/hr 568 568

Biomass (IS) kg/hr

Zymo (IS) kg/hr

Lignin (IS) kg/hr

Gypsum (IS) kg/hr

Ca(OH)2 (IS) kg/hr

Others (Insoluble Solids) kg/hr

Enthalpy Flow (millions) Kcal/hr -0.1 -0.8 -0.4 -4.1 -24.2 -35.6 -0.5 -36.4 -6.4 -34.4 0.0 -5.0 -24.2 -0.5

Average Density g/ml 1.0096 0.9983 1.0096 0.9983 1.0403 0.7753 0.6876 0.7872 1.8166 0.9983 0.0018 0.9983 1.0403 1.0096 I0203I.xls

Eq. No. Equipment Name Req.Spare Equipment Type Mat Const.

A-701 Denaturant In-line Mixer 1 STATIC SS304

A-720 CSL Storage Tank Agitator 1 FIXED-PROP SS304

A-760 CSL/DAP Day Tank Agitator 1 FIXED-PROP SS304

C-755 DAP Solids Feeder 1 ROTARY-VALVE A285C

P-701 Ethanol Product Pump 2 1 CENTRIFUGAL CS

P-703 Sulfuric Acid Pump 1 1 CENTRIFUGAL SS316

P-704 Firewater Pump 1 1 CENTRIFUGAL CS

P-710 Gasoline Pump 1 1 CENTRIFUGAL CS

P-720 CSL Pump 1 1 CENTRIFUGAL CS

P-750 Cellulase Pump 1 1 CENTRIFUGAL CS

P-755 DAP Unloading Blower 1 CENTRIFUGAL CS

P-760 CSL/DAP Pump 1 1 CENTRIFUGAL CS

S-755 DAP Vent Baghouse 1 FABRIC-FILTER A285C;POLYESTER

T-701 Ethanol Product Storage Tank 2 FLAT-BTM-STORAGEA285C

T-703 Sulfuric Acid Storage Tank 1 FLAT-BTM-STORAGESS316

T-704 Firewater Storage Tank 1 FLAT-BTM-STORAGEA285C

T-709 Propane Storage Tank 1 HORIZONTAL STORAGE A515

T-710 Gasoline Storage Tank 1 FLAT-BTM-STORAGEA285C

T-720 CSL Storage Tank 1 FLAT-BTM-STORAGESS304

T-750 Cellulase Storage Tank 2 FLAT-BTM-STORAGESS304

T-755 DAP Storage Bin 1 LIVE-BTM-BIN CS

T-760 CSL/DAP Day Tank 1 FLAT-BTM-STORAGESS304

Work Stream No. kW Work Stream No. kW

WC755 0.06 WP750 0.48

WP701 5.24 WP755 1.96

WP703 0.40 WP760 0.29

WP704 0.00 WT720 3.09

WP710 0.43 WT760 3.61

WP720 0.29
I0203I.xls

COMPONENT UNITS 261 560 804 804A 804B 804D 809 809A 810

Total Flow kg/hr 4,894 5,999 260,116 271,009 271,009 355,828 4,492 355,828 351,336

Insoluble Solids% 0.0% 0.0% 0.0% 0.0% 0.0% 1.3% 100.0% 1.3% 0.0%

Soluble Solids% 0.0% 0.1% 0.0% 0.0% 0.0% 0.3% 0.0% 0.3% 0.3%

TemperatureC 38 38 24 26 204 278 164 164

Pressure atm 1.00 3.20 1.00 1.01 1.01 0.97 0.97 0.97

Vapor Fraction 1.00 1.00 1.00 1.00 1.00 0.99 0.00 0.99 1.00

Ethanol kg/hr 0 0 0 0 0 0 0

Water kg/hr 205 74 3,382 3,661 3,661 67,617 67,617 67,617

Glucose (SS) kg/hr111

Xylose (SS) kg/hr7 7 7

Arabinose (SS) kg/hr2 2 2

Other Sugars (SS) kg/hr222

Cellobiose (SS) kg/hr333

Glucose Oligomers (SS) kg/hr 14 14 14

Xylose Oligomers (SS) kg/hr5 5 5

Other Oligomers (SS) kg/hr777

Corn Steep Liquor (SS) kg/hr0444 996 996 996

Others (Soluble Solids) kg/hr 74 74 74

Acetic Acid kg/hr 1 1 1 1 21 21 21

Sulfuric Acid kg/hr000222

Furfural kg/hr1022000

HMF kg/hr 0 0 0 0 0 0 0

Carbon Dioxide kg/hr 65,570 65,570 65,570

Methane kg/hr333

Oxygen kg/hr 984 1,243 59,411 61,638 61,638 10,273 10,273 10,273

Nitrogen kg/hr 3,702 4,677 197,324 205,703 205,703 206,283 206,283 206,283

Others kg/hr 0 0 0 0 402 402 402

Cellulose (IS) kg/hr 14 13 140

Xylan (IS) kg/hr4440

Arabinan (IS) kg/hr 1 1 1 0

Other Sugar Polymers (IS) kg/hr 1 1 1 0

Cellulase (IS) kg/hr6660

Biomass (IS) kg/hr1110

Zymo (IS) kg/hr 10 9 100

Lignin (IS) kg/hr 142 140 1422

Gypsum (IS) kg/hr 28 27 280

Ca(OH)2 (IS) kg/hr

Others (Insoluble Solids) kg/hr 4,342 4,290 4,342 52

Enthalpy Flow (millions) Kcal/hr -0.6 -0.2 -10.9 -11.7 0.2 -347.1 -12.0 -359.0 -347.0

Average Density g/ml 0.0011 0.0036 0.0012 0.0012 0.0007 0.0407 3.1415 0.0409 0.0012

Heat Stream No. MM kcal/hr Work Stream No. kW

QH801 11.86 WCOMBFAN 119.95

WM804 176.00

Eq. No. Equipment Name Req.Spare Equipment Type Mat Const.

H-801 Burner Combustion Air Preheater1 MISCELLANEOUS

M-804 Combustion Gas Baghouse1 FABRIC-FILTER A285C;FABRIC
I0203I.xls

COMPONENT UNITS 531 571 615 623 803 804B 804D 812 812B 813A 813B 814 815 815A 815E 816 816A

Total Flow kg/hr 39,922 44,075 625 218 84,215 271,009 355,828 184,771 14,240 190,485 190,485 37,234 95,287 16,665 16,486 16,486 16,486

Insoluble Solids % 2.4% 48.3% 0.0% 30.0% 26.5% 0.0% 1.3% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0%

Soluble Solids % 25.8% 4.9% 0.0% 0.1% 14.8% 0.0% 0.3% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0%

Temperature C 64 38 35 21 55 204 278 510 268 139 177 268 164 164 46 46 46

Pressure atm 0.21 3.20 1.00 1.00 1.00 1.01 0.97 86.06 13.00 98.31 97.63 13.00 4.42 4.42 0.10 0.10 4.20

Vapor Fraction 0.00 0.00 1.00 0.00 0.00 1.00 0.99 1.00 1.00 0.00 0.00 1.00 1.00 1.00 0.87 0.00 0.00

Ethanol kg/hr 0 3 0 0 3 0 0

Water kg/hr 23,957 19,783 28 152 43,893 3,661 67,617 184,771 14,240 190,485 190,485 37,234 95,287 16,665 16,486 16,486 16,486

Glucose (SS) kg/hr 57 6 63 1

Xylose (SS) kg/hr 629 70 0 699 7

Arabinose (SS) kg/hr 150 17 167 2

Other Sugars (SS) kg/hr 176 20 196 2

Cellobiose (SS) kg/hr 249 28 277 3

Glucose Oligomers (SS) kg/hr 1,282 144 1,426 14

Xylose Oligomers (SS) kg/hr 447 50 497 5

Other Oligomers (SS) kg/hr 670 75 746 7

Corn Steep Liquor (SS) kg/hr 992 0 0 992 4 996

Others (Soluble Solids) kg/hr 6,628 743 7,372 74

Acetic Acid kg/hr 1,757 363 0 0 2,120 1 21

Sulfuric Acid kg/hr 107 12 118 0 2

Furfural kg/hr 2 8 0 0 9 2 0

HMF kg/hr 0 1 0 0 1 0 0

Carbon Dioxide kg/hr 273 0 0 65,570

Methane kg/hr 324 0 0 3

Oxygen kg/hr 0 0 0 0 61,638 10,273

Nitrogen kg/hr 1 0 0 1 205,703 206,283

Others kg/hr 2,847 468 0 0 3,315 0 402

Cellulose (IS) kg/hr 20 1,337 1,358 14

Xylan (IS) kg/hr 7 430 437 4

Arabinan (IS) kg/hr 1 60 61 1

Other Sugar Polymers (IS) kg/hr 1 72 73 1

Cellulase (IS) kg/hr 244 325 568 6

Biomass (IS) kg/hr 0 0 65 65 1

Zymo (IS) kg/hr 408 544 952 10

Lignin (IS) kg/hr 214 13,967 14,181 142

Gypsum (IS) kg/hr 0 27 28 28

Ca(OH)2 (IS) kg/hr

Others (Insoluble Solids) kg/hr 69 4,528 4,597 4,342

Enthalpy Flow (millions) Kcal/hr -88.4 -136.2 -1.0 -0.6 -225.2 0.2 -347.1 -554.1 -44.2 -699.8 -692.4 -115.6 -300.3 -52.5 -53.9 -62.1 -62.1

Average Density g/ml 1.0845 1.3326 0.0009 1.1481 1.2092 0.0007 0.0407 0.0259 0.0055 0.9320 0.8963 0.0055 0.0023 0.0023 0.0001 0.9898 0.9899

Eq. No. Equipment Name Req. Spare Equipment Type Mat Const.

H-811 BFW Preheater 1 SHELL-TUBE SS304

M-803 Fluidized Bed Combustion Reactor 1 MISCELLANEOUS CS

M-811 Turbine/Generator 1 STEAM-TURBINE

P-811 Turbine Condensate Pump 2 CENTRIFUGAL SS304

Heat Stream No. MM kcal/hr Work Stream No. kW

QBOILER 118.35 WKNET -18747.45

QH811 -0.64 WP811 3.89

QM811 8.22 WPLANT 11717.68

WTOTAL -30465.14

821 823 840 860

5,715 14,240 0 4,858

0.0% 0.0% 0.0% 0.0%

0.0% 0.0% 0.0% 0.0%

309 190 25 115

96.26 12.32 1.00 1.68

0.00 0.00 1.00 0.97

5,715 14,240 4,858

0

-19.9 -51.6 0.0 -15.5

0.6925 0.8763 0.0007 0.0010
I0203I.xls

COMPONENT UNITS 591 593 595 597 811 811A 811B 812E 813 813A 815A 816A 821 823 861

Total Flow kg/hr 9,490 8,164 65,505 621 54,456 119,364 173,8200 190,485 190,485 16,665 16,486 5,715 14,240 4,858

Insoluble Solids% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0%

Soluble Solids% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0%

TemperatureC 148 148 148 148 26 115 87 137 139 164 46 309 190 115

Pressure atm 4.42 4.42 4.42 4.42 3.40 1.70 3.40 3.30 3.30 98.31 4.42 4.20 96.26 12.32 1.68

Vapor Fraction 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.00

Ethanol kg/hr

Water kg/hr 9,490 8,164 65,505 621 54,456 119,364 173,820 190,485 190,485 16,665 16,486 5,715 14,240 4,858

Glucose (SS) kg/hr

Xylose (SS) kg/hr

Arabinose (SS) kg/hr

Other Sugars (SS) kg/hr

Cellobiose (SS) kg/hr

Glucose Oligomers (SS) kg/hr

Xylose Oligomers (SS) kg/hr

Other Oligomers (SS) kg/hr

Corn Steep Liquor (SS) kg/hr

Others (Soluble Solids) kg/hr

Acetic Acid kg/hr

Sulfuric Acid kg/hr

Furfural kg/hr

HMF kg/hr

Carbon Dioxide kg/hr

Methane kg/hr

Oxygen kg/hr

Nitrogen kg/hr

Others kg/hr

Cellulose (IS) kg/hr

Xylan (IS) kg/hr

Arabinan (IS) kg/hr

Other Sugar Polymers (IS) kg/hr

Cellulase (IS) kg/hr

Biomass (IS) kg/hr

Zymo (IS) kg/hr

Lignin (IS) kg/hr

Gypsum (IS) kg/hr

Ca(OH)2 (IS) kg/hr

Others (Insoluble Solids) kg/hr

Enthalpy Flow (millions) Kcal/hr -34.7 -29.9 -239.7 -2.3 -206.3 -441.6 -647.9 -700.4 -699.8 -52.5 -62.1 -19.9 -51.6 -18.0

Average Density g/ml 0.8653 0.8653 0.8653 0.8653 0.9970 0.9467 0.9670 0.9283 0.9320 0.0023 0.9899 0.6925 0.8763 0.9466

Heat Stream No. MM kcal/hr Work Stream No. kW

WP804 20.46

WP824 11.44

WP826 719.27

WP828 1.80

Eq. No. Equipment Name Req. Spare Equipment Type Mat Const.

M-820 Hot Process Water Softener System1 PACKAGE

P-804 Condensate Pump2 CENTRIFUGAL SS316

P-824 Deaerator Feed Pump2 CENTRIFUGAL SS304

P-826 BFW Pump5 CENTRIFUGAL SS316

P-828 Blowdown Pump2 CENTRIFUGAL CS

T-804 Condensate Collection Tank1 VERTICAL-VESSEL A285C

T-824 Condensate Surge Drum1 HORIZONTAL-VESSELSS304

T-826 Deaerator1 HORIZONTAL-VESSELCS;SS316

T-828 Blowdown Flash Drum1 HORIZONTAL-VESSELCS
I0203I.xls

COMPONENT UNITS

Total Flow kg/hr

Insoluble Solids%

Soluble Solids%

TemperatureC

Pressure atm

Vapor Fraction

Ethanol kg/hr

Water kg/hr

Glucose (SS) kg/hr

Xylose (SS) kg/hr

Arabinose (SS) kg/hr

Other Sugars (SS) kg/hr

Cellobiose (SS) kg/hr

Glucose Oligomers (SS) kg/hr

Xylose Oligomers (SS) kg/hr

Other Oligomers (SS) kg/hr

Corn Steep Liquor (SS) kg/hr

Others (Soluble Solids) kg/hr

Acetic Acid kg/hr

Sulfuric Acid kg/hr

Furfural kg/hr

HMF kg/hr

Carbon Dioxide kg/hr

Methane kg/hr

Oxygen kg/hr

Nitrogen kg/hr

Others kg/hr

Cellulose (IS) kg/hr

Xylan (IS) kg/hr

Arabinan (IS) kg/hr

Other Sugar Polymers (IS) kg/hr

Cellulase (IS) kg/hr

Biomass (IS) kg/hr

Zymo (IS) kg/hr

Lignin (IS) kg/hr

Gypsum (IS) kg/hr

Ca(OH)2 (IS) kg/hr

Others (Insoluble Solids) kg/hr

Enthalpy Flow (millions) Kcal/hr

Average Density g/ml

Eq. No. Equipment Name Req.Spare Equipment Type Mat Const.

M-830 Hydrazine Addition Pkg.1 PACKAGE

M-832 Ammonia Addition Pkg1 PACKAGE

M-834 Phosphate Addition Pkg.1 PACKAGE

P-830 Hydrazine Transfer Pump1 CENTRIFUGAL CS

T-830 Hydrazine Drum1 VERTICAL-VESSEL SS316

Heat Stream No. MM kcal/hr Work Stream No. kW

WM830 10.00

WM832 10.00

WM834 10.00

WP830 0.02
I0203I.xls

COMPONENT UNITS 259 559 940 941 942 944 945 949

Total Flow kg/hr 4,687 5,921 12,256,909 158,828 9,330 14,439 12,256,909 135,059

Insoluble Solids% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0%

Soluble Solids% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0%

TemperatureC 40 40 37 28 28 28 28 28

Pressure atm 9.51 9.51 4.08 1.00 1.00 1.00 4.08 0.04

Vapor Fraction 1.00 1.00 0.00 0.00 0.00 0.00 0.00 1.00

Ethanol kg/hr

Water kg/hr 12,256,909 158,828 9,330 14,439 12,256,909 135,059

Glucose (SS) kg/hr

Xylose (SS) kg/hr

Arabinose (SS) kg/hr

Other Sugars (SS) kg/hr

Cellobiose (SS) kg/hr

Glucose Oligomers (SS) kg/hr

Xylose Oligomers (SS) kg/hr

Other Oligomers (SS) kg/hr

Corn Steep Liquor (SS) kg/hr

Others (Soluble Solids) kg/hr

Acetic Acid kg/hr

Sulfuric Acid kg/hr

Furfural kg/hr

HMF kg/hr

Carbon Dioxide kg/hr

Methane kg/hr

Oxygen kg/hr 984 1,243

Nitrogen kg/hr 3,703 4,678

Others kg/hr

Cellulose (IS) kg/hr

Xylan (IS) kg/hr

Arabinan (IS) kg/hr

Other Sugar Polymers (IS) kg/hr

Cellulase (IS) kg/hr

Biomass (IS) kg/hr

Zymo (IS) kg/hr

Lignin (IS) kg/hr

Gypsum (IS) kg/hr

Ca(OH)2 (IS) kg/hr

Others (Insoluble Solids) kg/hr

Enthalpy Flow (millions) Kcal/hr 0.0 0.0 -46287.8 -601.1 -35.3 -54.6 -46390.7 -432.8

Average Density g/ml 0.0106 0.0106 0.9819 0.9906 0.9906 0.9906 0.9906 0.0000

Eq. No. Equipment Name Req.Spare Equipment Type Mat Const.

M-902 Cooling Tower System1 INDUCED-DRAFT FIBERGLASS

M-904 Plant Air Compressor21 CENTRIFUGAL

P-902 Cooling Water Pump 1 1 CENTRIFUGAL CS

S-904 Instrument Air Dryer11 PACKAGE CS

T-902 Prehydrolysis Filter Air Receiver3 HORIZONTAL-PRESSURE CS

T-904 Plant Air Receiver1 HORIZONTAL-VESSELCS

T-905 Product Recovery Filter Air Receiver4 HORIZONTAL-PRESSURE CS

Heat Stream No. MM kcal/hr Work Stream No. kW

QCWCAP 102.94 WM902 657.67

WM904 1110.89

WP902 1258.33

WS904 7.36
I0203I.xls

COMPONENT UNITS 251 524 574 624 811 904 905 906 941 943

Total Flow kg/hr 71,466 35,912 104,579 95,805 54,456 186,649 263,552 145 158,828 96,281

Insoluble Solids% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0%

Soluble Solids% 0.1% 0.0% 0.0% 0.1% 0.0% 0.0% 0.1% 0.0% 0.0% 0.0%

TemperatureC 74 26 20 21 26 26 38 20 28 26

Pressure atm 3.00 1.00 1.00 1.00 3.40 1.00 1.00 1.00 1.00 1.00

Vapor Fraction 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Ethanol kg/hr 511 52

Water kg/hr 70,684 35,912 104,579 95,658 54,456 186,649 262,624 145 158,828 96,281

Glucose (SS) kg/hr

Xylose (SS) kg/hr000

Arabinose (SS) kg/hr00

Other Sugars (SS) kg/hr

Cellobiose (SS) kg/hr

Glucose Oligomers (SS) kg/hr

Xylose Oligomers (SS) kg/hr00

Other Oligomers (SS) kg/hr

Corn Steep Liquor (SS) kg/hr 96 79 175

Others (Soluble Solids) kg/hr

Acetic Acid kg/hr 5403 543

Sulfuric Acid kg/hr00

Furfural kg/hr 803 83

HMF kg/hr 120 13

Carbon Dioxide kg/hr00

Methane kg/hr00

Oxygen kg/hr11

Nitrogen kg/hr11

Others kg/hr3 58 60

Cellulose (IS) kg/hr

Xylan (IS) kg/hr

Arabinan (IS) kg/hr

Other Sugar Polymers (IS) kg/hr

Cellulase (IS) kg/hr

Biomass (IS) kg/hr

Zymo (IS) kg/hr

Lignin (IS) kg/hr

Gypsum (IS) kg/hr

Ca(OH)2 (IS) kg/hr

Others (Insoluble Solids) kg/hr

Enthalpy Flow (millions) Kcal/hr -265.8 -136.0 -396.6 -363.2 -206.3 -706.8 -993.6 -0.5 -601.1 -364.6

Average Density g/ml 0.9442 0.9925 0.9983 0.9973 0.9970 0.9925 0.9811 0.9983 0.9906 0.9925

Eq. No. Equipment Name Req. Spare Equipment Type Mat Const.

P-912 Make-up Water Pump 1 1 CENTRIFUGAL CS

P-914 Process Water Circulating Pump21 CENTRIFUGAL CS

T-914 Process Water Tank1 FLAT-BTM-STORAGECS

Heat Stream No. MM kcal/hr Work Stream No. kW

WP912 20.85

WP914 58.67
I0203I.xls

COMPONENT UNITS 906 909 914 916

Total Flow kg/hr 145 145 63 63

Insoluble Solids% 0.0% 0.0% 0.0% 0.0%

Soluble Solids% 0.0% 0.0% 0.0% 0.0%

TemperatureC 20 121 20 20

Pressure atm 1.00 1.00 1.00 1.00

Vapor Fraction 0.00 1.00 0.00 0.00

Ethanol kg/hr

Water kg/hr 145 145 63 63

Glucose (SS) kg/hr

Xylose (SS) kg/hr

Arabinose (SS) kg/hr

Other Sugars (SS) kg/hr

Cellobiose (SS) kg/hr

Glucose Oligomers (SS) kg/hr

Xylose Oligomers (SS) kg/hr

Other Oligomers (SS) kg/hr

Corn Steep Liquor (SS) kg/hr

Others (Soluble Solids) kg/hr

Acetic Acid kg/hr

Sulfuric Acid kg/hr

Furfural kg/hr

HMF kg/hr

Carbon Dioxide kg/hr

Methane kg/hr

Oxygen kg/hr

Nitrogen kg/hr

Others kg/hr

Cellulose (IS) kg/hr

Xylan (IS) kg/hr

Arabinan (IS) kg/hr

Other Sugar Polymers (IS) kg/hr

Cellulase (IS) kg/hr

Biomass (IS) kg/hr

Zymo (IS) kg/hr

Lignin (IS) kg/hr

Gypsum (IS) kg/hr

Ca(OH)2 (IS) kg/hr

Others (Insoluble Solids) kg/hr

Enthalpy Flow (millions) Kcal/hr -0.5 -0.5 -0.2 -0.2

Average Density g/ml 0.998 0.001 0.998 0.998

Heat Stream Mmkcal/hr Work Stream No. kW

QH910 -0.09 WM910 257.36

Eq. No. Equipment Name Req.Spare Equipment Type Mat Const.

M-910 CIP System1 MISCELLANEOUS CS
Appendix G

Changes from the 1999 Design Report
The following section describes the major changes that have been made since the 1999 design 

report. In general, the process changes came from a new feedstock, better design and cost 

information, the need to portray the current state of research in enzyme production, and the 

change to target yields for pretreatment and co-fermentation that can be achieved in the next 

several years. Other minor changes (to the mass and energy balance model) had a small 

combined cost effect. 

Corn Stover Feedstock 

The change in feedstock from yellow poplar hardwood chips to corn stover is a major one. There 

are fewer carbohydrates in corn stover than hardwood, so the theoretical of ethanol yield per ton 

of feedstock is lower. The feedstock cost of $30 per dry short ton is an increase from wood chips 

at $25 per dry short ton. The cost represents our current understanding of the expected harvesting 

capabilities, transportation and farmer costs required to obtain stover in 2010. ORNL has been 

instrumental in providing us with information on feedstock costs to use in the process model, and 

continues to work towards a better understanding of the availability and cost of stover. 

It is assumed that the bales would be stored in several locations until needed. The cost of offsite 

storage for the once-per-year harvest of stover was not included in this design. 

The change from a loose, piled feedstock like wood chips to baled stover presented several 

changes in the feedstock receiving and handling area, including moving the bales, breaking them 

up, and making the stalks and other long pieces small enough to feed to the pretreatment reactors. 

Corn stover also contains a higher percentage of dirt and less moisture than wood chips, so dust 

and debris were issues. The Harris group looked at several designs for moving, unbaling, 

washing, and shredding baled corn stover, and picked one based on its performance in existing 

similar applications. The total installed cost of $7.5MM for stover handling equipment was 

$2.6MM higher than that for wood chips. The stover handling equipment was also sized on a dry 

feed rate unlike the wood chip handling equipment, which was sized on a total feed rate basis. It 

is conceivable that this system is overdone, and the washing and size reduction could be reduced 

as we learn to handle or minimize the dirt picked up in harvesting and gain a better understanding 

of the effect of particle size. 

Labor for the baled feedstock was a significant change - eight forklift operators per shift for corn 

stover versus two bulldozer drivers for chips. Because the bales are trucked in and must be 

unloaded, a substantial amount of bale moving is anticipated. 

Pretreatment Reactor and Yields 

The Harris Group contacted several vendors for design and cost information to augment the 

information we obtained from Sunds through Delta-T. Anco-Eaglin and Andritz provided 

detailed estimates. Both companies specified lower cost metallurgy for the wetted parts (Incoloy 

825 clad steel and Incoloy 825, respectively) than Sunds originally did (Hastelloy C-2000) for the 

pretreatment conditions. Harris contracted with a corrosion lab and corrosion consultant to 

conduct testing on these materials. The lower cost of the Anco-Eaglin system provided a savings 

of about $5.5MM in purchased and $2.5MM in installed equipment cost over the Sunds unit. The 

reason for this decrease in savings as the installation factor is applied is that the Anco-Eaglin 

system has a larger installation factor of 2.29 versus a factor of 1.5 for the Sunds unit. Yield 

targets were increased from 75 to 90% for hemicellulose to monomer conversion. 
Solid-Liquid Separation Equipment 

A significant portion of the Harris Group’s work was with solid-liquid separation vendors in an 

attempt to optimize the design of equipment for both separation of prehydrolyzate slurry and 

post-distillate slurry. As a result of vendor testing over a wide range of separator types, a 

Pneumapress pressure filter was chosen for the prehydrolyzate slurry application based on its 

performance in solid recovery, cake dryness, and washing ability. When compared against the 

other quotes (for horizontal belt filters), the Pneumapress filter’s estimated installed cost was 

$2.2MM more than the closest cost quote, but $18.5MM less than the highest quote. However, 

its separation and washing efficiencies were superior to the horizontal belt filters. The installed 

cost of the Pneumapress system was about $4MM higher than our current estimate for a belt filter 

press ($6.3MM installed cost for the Pneumapress and peripherals compared to $2.1MM for the 

belt filter press), however, it allows for washing with a minimal amount of liquid, and has been 

verified through vendor testing. 

For the post-distillate solids, the Pneumapress system used here is again about $4MM more 

expensive than the prior centrifuge cost ($6.4MM versus $2.4MM), but also allows the removal 

of the solids dryer ($2.2MM). The flue gas, previously used for drying, can now be used in a 

combustion air preheater ($1.1MM). Also, Harris’ estimated installed cost for a centrifuge 

system in this application (including all extraneous equipment such as pumps, conveyors, etc.) 

was $0.7MM more expensive than that of the Pneumapress system. Because this data was based 

on vendor tests, we consider it more reliable than the previous separation equipment costs used 

Enzymatic Hydrolysis (Saccharification) and Co-Fermentation 

Based on our current understanding of what production of the first commercially available 

enzyme preparation for lignocellulosic biomass will entail, a cost of $0.10 per gallon of ethanol 

was used for enzyme delivered to the plant from a local enzyme facility. This is a major change 

from the previous design, which assumed on-site fermentation of the enzyme using T. Reesei 

fungi (previously Area 400 in the design). The installed capital ($15.5MM) and operating costs 

associated with that production were about $0.30 per gallon ethanol. The electrical demand of 

the plant is roughly halved without the enzyme production fermenters. Chilled water demand is 

also greatly reduced by removing cellulase production. 

In preparation for an improved thermal tolerant enzyme, the SSCF process was separated into 

separate saccharification and co-fermentation. The saccharification yield target was increased 

and the fermentation yield target for glucose was also increased. 

Other Changes 

1. Distillation column costing

Both the beer column and rectification distillation column capital costs are now scaled by the 

square of the diameter (previously just the diameter), to better represent the size (and hence cost) 

by a variable that is proportional to cross-sectional flow. 

2. Solids Dryer Testing

In the current design, the solids fed to the boiler are not being dried, due to the high efficiency of 

the Pneumapress unit. The previous design used a centrifuge, and required a dryer to get the total 

boiler feed moisture content low enough to support combustion. A rotary drum dryer, similar to 

those used to dry the Distiller’s Dried Grains (DDG) in the corn ethanol industry was used with 
the hot flue gas as the heat source. The cost of the dryer was about $2.2MM, and was 

incorporated into the design (replacing the rotary drum dryer) until the Pneumapress unit replaced 

it and the centrifuge in this new design. 

Summary of Significant Changes 

1999 Design Report 2002 Design Report Ethanol Selling 

Price ($/gal) 

1999 Reported Cost 

(Model: R9906A, 1997 $) $1.44 

Feedstock Hardwood Chips Corn Stover +$0.06 

Feedstock Cost $25 per dry ton $30 per dry ton +$0.07 

Feedstock Handling 

Installed Cost $4.9MM $7.5MM +$0.02 

Feedstock Handling Labor 2 per shift 8 per shift +0.02 

Pretreatment Reactor Hastelloy C-2000 Incoloy 825 clad steel -$0.01 

Pretreatment Targets and 

Conditions 

75% Hemicellulose to 

Monomer Yield 

190°C 0.5% acid, 10 

minutes 

90% Hemicellulose to 

Monomer Yield 

190°C, 1.1% acid, 2 

minutes -$0.06 

Conditioning Ion exchange and 

overliming Overliming only -$0.08 

Solid-Liquid Separation 

Equipment 

Belt Filter 

Press/Centrifuge 

Pneumapress Pressure 

Filters +$0.01 

Enzyme Produced on-site for 

$0.30 per gallon ethanol 

Purchased for $0.10 per 

gallon ethanol -$0.20 

Enzymatic Hydrolysis and 

Fermentation Configuration 

SSCF Saccharification and CoFermentation -$0.01 

Fermentation Targets 73.6% Cellulose to 

Ethanol Yield 

85.5% Cellulose to 

Ethanol Yield 

-$0.15 

85% Xylose to Ethanol 

Yield 

85% all Hemicelluosic 

Sugars to Ethanol Yield 

-$0.10 

Cost Year Change 1997 2000 +$0.04 

Other Minor Model Fixes +$0.02 

2002 Reported Cost 

(Model: I0203I, 2000 $ $1.07 
Appendix H

Chemical Formulas for Biomass Compounds
Chemical Formulas for Biomass Compounds 

Compound Name Chemical Formula Notes 

Acetate C2H4O2 

Arabinan C5H8O4 Use Xylan Properties 

Arabinose C5H10O5 Use Xylose properties 

Cellobiose C12H22O11 Use Glucose properties 

Cellulose C5H10O5 

Corn Steep Liquor (CSL) Unknown Modeled as water 

Furfural C5H4O2 

Galactan C6H10O5 Use Cellulose properties 

Galactose C6H12O6 Use Glucose properties 

Glucose C6H12O6 

HydroxyMethylFurfural (HMF) C5H4O2 Use Furfural properties 

Lignin C10H13.9 O1.3 

Mannan C6H10O5 Use Cellulose properties 

Mannose C6H12O6 Use Glucose properties 

Soluble Lignin C10H13.9 O1.3 Use Glucose properties for 

liquid-liquid interactions 

Tar C5H8O4 Use Xylan Properties 

Xylan C5H8O4 

Xylose C5H10O5 

Z. mobilis CH1.8 O0.5 N0.2 
Appendix I 

Physical Property Model and 

Parameters for Distillation 
Physical property models and parameters are important throughout a rigorous mass and energy 

balance model such as the one used here. This is even truer for distillation calculations involving 

azeotropes such as the separation of ethanol from water. The physical property optioni

 selected 

for this ASPEN model uses the NRTLii activity coefficient (g i ) model for the liquid phase 

fugacity, fi 

λ , calculation. The vapor phase is modeled using the ideal gas law, which makes the 

vapor fugacity coefficient equal to one. The vapor phase fugacity coefficient is not nearly as 

important as the liquid phase fugacity because of the low-pressure operation. 

The liquid phase equation for liquid fugacity is: 

fi = xi g i fi 

*,λ 

The pure component liquid fugacity, fi 

*,λ , reduces to the pure component vapor pressure, pi *,λ , at 

low pressures (the Poynting correction is unity). The NRTL activity coefficient model and vapor 

pressure models used by ASPEN are given below. Tables 11 and 12 give the ethanol and water 

parameters for those equations. 

x jt jiG ji x j

Gij 

 ∑ xmtmjGmj  

m 

∑ xkGki 

ln g i = + j

j ∑ xkGkj  

tij 

∑ xkGkj 

 

k k  k  

Where: 

Gij = exp( aijt ij ) 

tij = aij + ij 

T 

b

+ eij ln T + fijT 

aij = cij + dij (T − 273.15) 

tii = 0 

Gii = 1 

aij ≠ a ji 

bij ≠ bji 

cij = c ji 

dij = d ji 

Vapor Pressure Correlation 

*, ln pi = C1i + 

C2i + C4i

T + C5i ln T + C6iT C 7 i

T + C3i 
NRTL Activity Coefficient Model Parameters iii 

aij 0 

aji 0 

bij -55.1698 

bji 670.4442 

cij 0.3031 

dij 0 

eij 0 

eji 0 

fij 0 

fji 0 

Lower Temperature Limit 348.15 

Upper Temperature Limit 373.15 

Note: i – ethanol, j – water 

Vapor Pressure Model Parameters iii 

Eq. Parameters Ethanol Water 

C1 74.475 73.649 

C2 -7164.3 -7258.2 

C3 0 0 

C4 0 0 

C5 -7.3270 -7.3037 

C6 3.1340E-06 4.1653E-06 

C7 2 2 

Lower Temperature Limit 159.05 273.16 

Upper Temperature Limit 513.92 647.13 

Temperature Units, Kelvins 

Pressure Units, Pascals 

i

 “ASPEN PlusTM, Reference Manual–Volume 2, Physical Property Methods and Models,” Release 9.3, 

Aspen Technology, Inc., Cambridge, MA, 1996.

ii Renon, H., and J.M. Praustniz, “Local Composition in Thermodynamic Excess Functions for 

Liquid Mixtures,”AIChE J., 14(1), 135, 1968.

iii “ASPEN PlusTM, Reference Manual–Volume 3, Physical Property Data,”Release 9.3, Aspen 

Technology, Inc., Cambridge, MA, 1996.
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1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE 

June 2002 

3. REPORT TYPE AND DATES COVERED 

Technical Report 

4. TITLE AND SUBTITLE 

Lignocellulosic Biomass to Ethanol Process Design and Economics Utilizing Co-Current Dilute 

Acid Prehydrolysis and Enzymatic Hydrolysis for Corn Stover 

5. FUNDING NUMBERS 

TA: BFP2.A410 

6. AUTHOR(S) 

A. Aden, M.Ruth, K. Ibsen, J. Jechura, K. Neeves, J. Sheehan, B. Wallace 

L. Montague, A. Slayton, J. Lukas 

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 

Biotechnology Center for Fuels and Chemicals 

National Renewable Energy Laboratory 

Golden, CO 80401 

Harris Group 

Seattle, WA 98109 

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REPORT NUMBER 

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National Renewable Energy Laboratory 

1617 Cole Blvd. 

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13. ABSTRACT (Maximum 200 words) 

This report is an update of NREL’s ongoing process design and economic analyses of processes related to developing ethanol from 

lignocellulosic feedstocks. 

14. SUBJECT TERMS 

process design; economic analyses; acid prehydrolysis; enzymatic hydrolysis 

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