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MEMORANDUM

DATE: July 1, 2014

TO: Air and Radiation Docket EPA-HQ-OAR-2012-0401

SUBJECT: Additional Detail on the Calculation of the Cellulosic Converted Fraction, 

and Attribution of Batch RINs for D-code Dependent Feedstocks

This memorandum provides additional information about the implications for cellulosic fuel producers 

processing biomass with an adjusted cellulosic content below EPA’s cellulosic content threshold of 75%.

This memorandum may also be informative to biofuel producers who generate a single type of fuel by 

simultaneously processing multiple feedstocks. All cellulosic biofuel processes using biomass feedstocks

must employ a process with the demonstrated capability of converting cellulosic material to biofuel. 

However, fuel produced using a single type of biomass with an adjusted cellulosic content greater than 

75% (e.g., corn stover or switchgrass) will be allowed to generate cellulosic renewable identification 

numbers (RINs) for the entire fuel volume, while producers using a single type of biomass with an 

adjusted cellulosic content below 75% will have to apportion different D-codes to the RINs produced 

based on the amount of cellulosic and non-cellulosic fuel produced. In practice, such producers will treat 

a single type of biomass material as two separate feedstocks – one cellulosic feedstock and one noncellulosic feedstock – and allocate RINs using existing regulations for generating fuels using multiple 

feedstocks. For most producers this apportionment will be straight-forward, but for producers 

simultaneously processing cellulosic and non-cellulosic feedstocks in a single reactor using a biochemical 

process, the apportionment will be more complicated and require additional record keeping and 

reporting requirements. The regulatory framework EPA established to verify that the number of 

cellulosic RINs generated by such processes corresponds to the volume of the cellulosic biofuel 

produced involves verifying that the calculated converted fraction (CF) applied to each portion of the 

feedstock material (cellulosic and non-cellulosic) is accurate. Establishing the accuracy of these 

determined CF values requires obtaining reasonably accurate feedstock and process data, which are 

used to perform a mass balance accounting of the various feedstock materials. This allows portions of 

the final fuel to be attributed either to the cellulosic or non-cellulosic portions of the biomass used as

feedstock. This memorandum explains: 1) why EPA has established separate requirements for various 

types of processes, 2) what types of data can be considered reasonably accurate to form the basis for 

calculating cellulosic and non-cellulosic CF values for feedstocks, and 3) how accurate feedstock CF 

values can be used in existing regulations to apportion RINs for a single type of fuel produced from 

multiple feedstocks (including single types of biomass that have less than 75% adjusted cellulosic 

content, and are treated as two feedstocks under EPA regulations).
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I. Background

a. The cellulosic content threshold, and the implications for feedstocks with lower cellulosic 

contents

EPA is finalizing a cellulosic content threshold for feedstocks to qualify for cellulosic RINs for the total 

volume of fuel produced.1 If a feedstock has an average adjusted cellulosic content of at least 75%, all of 

the fuel produced from the feedstock is eligible to generate cellulosic RINs2. “Adjusted cellulosic 

content” is the percent of organic matter that is cellulosic material (cellulose, hemicellulose, and lignin). 

In other words, the “adjusted cellulosic content” is adjusted so as not to include the inorganic (ash) 

components of the feedstock. This adjustment is appropriate because the inorganic portion of 

feedstock is not converted biofuel.

Where a biofuel producer is seeking to generate cellulosic RINs from a single type of biomass, but the 

biomass contains less than 75% adjusted cellulosic content, the biomass must be treated as two 

separate feedstocks; one cellulosic and the other non-cellulosic. In such cases, as well as in situations 

where biofuel producers convert two or more different types of biomass simultaneously, producers are

eligible to generate cellulosic RINs for a percentage of the fuel produced, based on the cellulosic 

converted fraction and the equations in 40 CFR 80.1426(f)(3)(vi). The purpose of this memorandum is 

to provide details on how the cellulosic converted fraction can be calculated, and examples of methods 

that may be used to generate the data needed to calculate the cellulosic converted fraction.

b. Registration, reporting and record keeping requirements for thermochemical and 

biochemical processes

EPA is requiring all producers of cellulosic RINs converting cellulosic biomass to complete additional 

registration requirements. These additional requirements are designed to demonstrate that the process 

being registered is capable of performing cellulosic biomass conversion. Additionally, as part of the 

engineering review, the relevant unit process equipment to perform the described conversion to biofuel

will be confirmed to be both in place and operational.

Process technology plays a key role in how much of the final fuel product is derived from cellulose, 

hemicellulose, or lignin. The two basic processes for converting cellulosic feedstocks into biofuel are

thermochemical and biochemical. Thermochemical processes mainly consist of pyrolysis – in which 

cellulosic biomass is decomposed with temperature to form bio-oils that can be further processed to 

produce a finished fuel – and gasification – in which cellulosic biomass is decomposed to form synthesis 

gas (“syngas”) that with further catalytic processing can produce a finished fuel product. 

Thermochemical processes typically convert all of the organic components of the feedstock into finished 

fuel, and the portion of the finished fuel derived from cellulosic material is proportional to the cellulosic 

content of the organic fraction of the feedstock. Therefore, EPA’s additional registration requirements 

for thermochemical producers are intended to demonstrate how much of the feedstock is cellulosic, and 

 

1

See Notice of Final Rulemaking placed in docket EPA-HQ-OAR-2012-0401.

2

One of the requirements for all cellulosic biofuel pathways converting cellulosic biomass is that the producer uses 

a method that produces fuel from the cellulosic portion of the feedstock. 
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that the conversion equipment to be used in the process is both in place and operational at the time of 

registration. 

By contrast, the biochemical process first requires the release of sugars from biomass and then the use 

of microorganisms to convert the sugars into fuels. The amount of cellulosic material converted to fuel 

will depend on the details of the process, such as the types and combinations of enzymes used. 

Variations from process to process will establish different hydrolysis efficiencies for cellulosic and noncellulosic carbohydrates. Thus, for biochemical processes, the cellulosic portion of the fuel will not 

necessarily be proportional to the cellulosic composition of the feedstock.

For in situ processes, where cellulosic and non-cellulosic material are simultaneously hydrolyzed to 

intermediate sugars or converted to fuel, the registration, reporting, and recordkeeping requirements, 

as well as the method for determining the cellulosic converted fraction, are different depending on 

whether the cellulosic biomass is converted by a biochemical or a thermochemical process. EPA’s 

additional registration and record keeping requirements for in situ biochemical producers of cellulosic 

fuel are intended to establish and monitor the relative conversion efficiencies for both the cellulosic and 

non-cellulosic portions of the feedstock in order to ensure that RIN assignments have been made 

appropriately. 

II. Definition of the cellulosic Converted Fraction

EPA defines the converted fraction (CF) to be the average mass percent (typically a yearly average) 

representing that portion of the feedstock that is converted into renewable fuel. The CF is calculated by 

dividing the dry mass of the feedstock that is converted to renewable fuel by the dry mass of the 

feedstock that is capable of being converted to fuel. Calculating separate CF and cellulosic CF values 

among in situ biochemical processes can be complicated because the mass of the resulting fuel 

corresponding to the non-cellulosic and cellulosic portions cannot be directly measured. However, 

existing EPA regulations detail how RINs can be allocated where multiple feedstocks are being 

simultaneously processed. This memo provides more detail on how the formulas in 80.1426(f)(3)(vi) 

should be used to calculate RINs. 

III. Description of possible process configurations for biochemical and “in situ” biochemical processes

Biochemical processes typically employ engineered yeast strains to ferment aqueous sugars into 

alcohols that can be separated and used as biofuels. Release of sugars from complex carbohydrates is 

facilitated by enzymatic treatment in a process called hydrolysis. The polymeric linkages in these 

carbohydrates can be cellulosic or non-cellulosic, and this distinction determines which enzymatic 

treatment will result in hydrolyzing the chemical bonds linking the sugars together. In this case, enzymes 

can be viewed as keys that un-lock the sugars, and only the proper key will fit a particular chemical 

bond’s lock. Released sugars will be converted to biofuel in the same manner regardless of whether 

they were derived from cellulosic or non-cellulosic carbohydrates. Therefore, hydrolysis is the critical 

step controlling the fraction of the finished fuel that can be considered to be derived from cellulosic 
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material. Determining the extent to which the cellulosic portion of a feedstock was hydrolyzed can be 

quantified in a number of ways, but this validation is more difficult for processes that perform in situ

hydrolysis of both the cellulosic and non-cellulosic feedstock portions. This is due to the fact that the 

fraction of sugars or fuel derived from either type of carbohydrate cannot be measured directly, but 

rather requires a mass balance accounting to identify the source of the sugars or fuel. Figure 1 shows a 

simplified example of a biochemical process performing in situ biochemical hydrolysis, and Figure 2 

shows a separated hydrolysis scenario. 

Figure 1 – Simplified schematic of a biochemical biofuel process with in situ hydrolysis

Figure 2 – Simplified schematic of a biochemical biofuel process with separated hydrolysis 
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To determine the relative amounts of cellulosic and non-cellulosic feedstock that are hydrolyzed, a mass 

balance accounting of the converted feedstock and resulting products and co-products is required.

There are a number of ways to perform a mass balance accounting for the converted portion of the 

cellulosic feedstock. It will be easier for producers using separated hydrolysis because the cellulosic 

conversion can be quantified directly from the cellulosic hydrolysis unit as indicated by the dashed 

boundary line in Figure 2. In this case, complex analysis of the inputs and outputs is not required 

because the aqueous sugars in the hydrolysis unit’s effluent are assumed to be derived from cellulosic 

carbohydrates. Similarly, if cellulosic hydrolysis occurred as a separate step, and the resulting 

intermediates from that step were segregated and fermented separately, then all of the resulting fuel 

from this process would be cellulosic. A direct accounting for the converted cellulosic fraction will allow 

RINs to be easily attributed.

By contrast, in situ processes require a more complex mass balance accounting to confirm the portions 

of the biofuel resulting from cellulosic hydrolysis relative to non-cellulosic hydrolysis. Assessment 

methods can be designed in a number of ways, but would typically account for cellulosic conversion by 

either quantifying overall biofuel increases relative to non-cellulosic treatment, or by directly analyzing 

the structural make-up of the feedstock and residual materials, as well as the overall fuel yield, in order 

to determine relative feedstock conversion. EPA is allowing producers to design analytical protocols 

specific to their process configuration as long as the mass balance accounting calculation method is 

verified by an independent third party engineer, these calculations can independently identify both a 

cellulosic and non-cellulosic CF, the data used to perform the calculations is regularly reported along 

with the calculated CF values, and the data itself is collected and reported in a scientifically reasonable 

manner.

IV. Expectations for data collection and analysis

a. General requirements regarding data used to calculate CF

EPA is providing clarifying information on the type of methods that may be used to generate data to 

calculate the cellulosic converted fraction. Data used to calculate the cellulosic CF must be obtained 

using an analytical method certified by a voluntary consensus standards body (VCSB), or using a nonVCSB method that would produce reasonably accurate results. If a VCSB-approved method is not used

to generate the data required to calculate the cellulosic CF for a given process, then the producer will 

need to show that the method used is an adequate means of generating the data by providing peer 

reviewed references to the third party engineer performing the engineering review at registration. An 

example of an appropriate VCSB test method certified by a voluntary consensus standards body for 

assessing the cellulosic content of a feedstock is ASTM E1758, entitled, “Determination of 

Carbohydrates in Biomass by High Performance Liquid Chromatography.” Since this ASTM test method 

has been adjudicated through the voluntary consensus standards body process we are confident in its 

use in practice. An example of another type of method would be a non-voluntary consensus standards 

body test method such as the National Renewable Energy Laboratory (NREL) Laboratory Analytical 
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Procedure to measure structural carbohydrates3and is an example of such a methodology that is 

commonly presented in peer-reviewed literature.4 Since this NREL method has not been adjudicated 

through the voluntary consensus standards body process, the user of these types of non-VCSB test 

methods will be required to provide peer reviewed references to the third party engineer performing 

the engineering review at registration to show that the non-VCSB method used is an adequate means of 

generating the data. These are examples of test methods that quantify the amount of cellulose, 

hemicellulose, and/or lignin in biomass. Data from these analyses can be used in a mass balance 

equation to determine the cellulosic CF. In the next sections we describe these methods in more detail, 

as well as some other methods that can be used to determine the cellulosic fraction of a feedstock. This 

information, in turn, can be used to calculate the cellulosic CF of the finished fuel.

b. Structural Carbohydrate Analysis

One method of determining the cellulose and hemicellulose content of biomass is using a High 

Performance Liquid Chromatography (HPLC) structural carbohydrate analysis, also known as a dietary 

fiber analysis. This type of structural carbohydrate analysis has been commonly used by researchers 

who are interested in the composition of a feedstock that will be used for biofuel.

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 For this type of test,

acid hydrolysis is used to break down both cellulose and hemicellulose into monomeric sugars (i.e., 

cellulose is converted to glucose; hemicellulose is converted to xylose, galactose, arabinose, and 

mannose). The concentrations of these sugars are measured using HPLC. The glucose concentration 

can be used as a measure of the cellulose concentration in the plant, and the sum of the xylose, 

galactose, arabinose, and mannose concentrations can be used as a measure of the hemicellulose 

concentration. The sample can also be analyzed for acetyl content, which is part of hemicellulose. 

Examples of this type of procedure are the National Renewable Energy Lab (NREL) Laboratory Analytical 

Procedure, “Determination of Structural Carbohydrates and Lignin in Biomass” and ASTM E1758, 

“Determination of Carbohydrates in Biomass by High Performance Liquid Chromatography.” Although 

this type of method has been successfully used to measure cellulose and hemicellulose for many 

feedstocks, an important caveat is that the results obtained are highly dependent on the exact methods 

used, and small changes to the procedures can have a large effect on the results.6In addition, the NREL 

 

3

“Determination of Structural Carbohydrates and Lignin in Biomass,” National Renewable Energy Laboratory. 

Available at: http://www.nrel.gov/biomass/analytical_procedures.html

4

See e.g. Sluiter, J.B. et al. (2010) Compositional Analysis of Lignocellulosic Feedstocks. 1. Review and Description 

of Methods. Journal of Agricultural and Food Chemistry, 58, 9043-9053. Templeton, D.W. et al. (2010) 

Compositional Analysis of Lignocellulosic Feedstocks. 2. Method Uncertainties. Journal of Agricultural and Food 

Chemistry, 58, 9054-9062. 

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E.g. Guo, G. et al., 2009. “Characterization of enzymatic saccharification for acid-pretreated lignocellulosic 

materials with different lignin composition.” Enzyme and Microbial Technology, 45:80-87; Dahlberg, J. et al., 2011. 

“Compositional and agronomic evaluation of sorghum biomass as a potential feedstock for renewable fuels.” 

Journal of Biobased Materials and Bioenergy, 5:1-7; Fedenko, J.R. et al. 2013. “Biomass production and 

composition of perennial grasses grown for bioenergy in a subtropical climate across Florida, USA.” Bioenergy 

Research, 6:1082-1093.

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For example, using a sample particle size that is smaller than recommended can cause a low bias in measured 

carbohydrate content. For more details about how procedure changes can affect the results, see the Laboratory 

Analytical Procedures, “Summative Mass Closure” and “Determination of Structural Carbohydrates and Lignin in 
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and ASTM procedures warn that biases may be introduced if the sample has a high protein content, or if 

extractives have not been removed. 

Because the HPLC structural carbohydrate analysis only measures cellulose and hemicellulose, a 

separate method is needed to measure the lignin concentration. A procedure for measuring the lignin 

concentration is detailed in the NREL method cited above, as well as in ASTM E1721 “Determination of 

Acid-Insoluble Residue in Biomass.” Briefly, the acid hydrolysis step that breaks down the cellulose and 

hemicellulose also separates lignin into an “acid soluble” portion and an “acid insoluble” portion. The 

concentration of acid soluble lignin can be measured using a UV-Visible spectrophotometer. The 

concentration of acid insoluble lignin can be measured gravimetrically. 

In addition to the HPLC structural carbohydrate method, near infrared spectroscopy (NIRS) can be used 

to determine the structural carbohydrate composition, as well as the presence of other components.

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NIRS measures the chemical bonds in a biomass sample, which can be used to determine its

composition. This method is rapid and non-destructive. In order for measurements to be made using 

NIRS, the spectra must be calibrated using other methods, such as an HPLC compositional analysis. 

c. Detergent Fiber Analysis

For a determination of the total fiber content of biomass, a neutral detergent fiber (NDF) test can be 

used. The NDF method dissolves non-fiber components such as proteins, lipids, and sugars. The 

leftover material is the total fiber, which can be measured gravimetrically. This method is detailed in 

AOAC 2002.04 Amylase-Treated Neutral Detergent Fiber in Feeds.

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 This method is commonly used for 

determining the forage potential of biomass.

The NDF method can be used along with an acid detergent fiber (ADF) test and an acid detergent lignin 

(ADL) test to determine the amount of cellulose, hemicellulose and lignin, rather than just the total fiber 

content. The ADF method breaks down hemicellulose, so that cellulose and lignin remain. The 

measurement of ADF can be subtracted from the measurement of NDF to determine the concentration 

of hemicellulose in the sample. The ADL test measures the lignin concentration by breaking down both

cellulose and hemicellulose using sulfuric acid and ignition. The ADL measurement can be subtracted 

from the ADF measurement to determine cellulose concentration. The detergent fiber analyses are

much simpler than the HPLC structural carbohydrate analysis. However, these two types of methods do 

not always give the same results. For example, one study showed that the detergent fiber methods 

overestimate cellulose and hemicellulose and underestimate lignin relative to the structural 

 

Biomass,” National Renewable Energy Laboratory. Available at: 

http://www.nrel.gov/biomass/analytical_procedures.html

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E.g. Sanderson, M.A. et al., 1996. “Compositional analysis of biomass feedstocks by near infrared reflectance 

spectroscopy.” Biomass and Bioenergy, 11(5):365-370; Vogel, K.P. et al., 2011. “Quantifying actual and theoretical 

ethanol yields for switchgrass strains using NIRS analyses.” Bioenergy Research, 4:96-110.

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See also, Mertens, D.R., 2002. “Gravimetric determination of amylase-treated neutral detergent fiber in feeds 

with refluxing in beakers or crucibles: Collaborative study.” Journal of AOAC International, 85(6):1217-1240.
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carbohydrate analysis.9 Another study has shown that NDF and ADF cannot be used to accurately 

determine glucan and xylan content of the fiber portion of a feedstock.

10 Even though the detergent 

fiber analyses do not give the same measurements of cellulose, hemicellulose, or lignin as the HPLC 

structural carbohydrate analysis, the NDF method does give a good measure of the sum of cellulose, 

hemicellulose, and lignin. For cases where only the total cellulosic content (cellulose, hemicellulose, and 

lignin) or the adjusted cellulosic content is required, rather than separate measurements of cellulose, 

hemicellulose and lignin, the NDF method is appropriate. 

d. Quantification of Starch Content 

Measurement of the starch content can be used to indirectly determine the cellulosic converted 

fraction. 11 To measure the starch content, enzymes are used to convert the starch to maltodextrin and 

then to glucose. A subsequent reaction forms a dye in proportion to the amount of glucose present. The 

absorbance of this dye is measured with a spectrophotometer. Standards are used to calibrate the 

spectrophotometer measurements and determine the starch content of the initial sample. Because 

both starch and cellulosic material can be converted to fuel, a measure of the starch content of the 

feedstock and residual material after conversion can give information about how much starch was 

converted to fuel, which would help determine the cellulosic converted fraction. 

V. Allocating RINs using the 1426 equations

a. Description of how EPA views cellulosic and non-cellulosic components of a feedstock as 2 

separate feedstocks for RIN allocation

For simplicity, EPA selected to specify that if a single plant’s average adjusted cellulosic content is less 

than 75%, then the feedstock is considered to be two feedstocks – specifically a cellulosic and noncellulosic feedstock. This designation allows the equations in Table 4 to 80.1426 to be used to allocate 

both cellulosic and non-cellulosic RINs for the resulting mixed batch of fuel. This will require a separate 

converted fraction (CF) to be calculated for both the cellulosic and non-cellulosic fractions. 

b. Calculation of the cellulosic CF and identification of the volume of D3-RINs

The converted fraction (CF) is a unitless average mass percent representing that portion of the feedstock 

that is converted into renewable fuel. This is calculated by dividing the mass of the feedstock that is 

converted to renewable fuel by the mass of the feedstock that is capable of being converted to fuel. For 

in situ biofuel producers, this calculation will require some type of material balance accounting because 

the fuel will be a mixture of both cellulosic and non-cellulosic fuel.

 

9

Dien, B.S., et al., 2006. “Chemical composition and response to dilute-acid pretreatment and enzymatic 

saccharification of alfalfa, reed canarygrass, and switchgrass.” Biomass and Bioenergy, 30:880-891.

10 Wolfrum, E.J., et al., 2009. “Correlating detergent fiber analysis and dietary fiber analysis data for corn stover 

collected by NIRS.” Cellulose, 16:577-585.

11 e.g. Megazyme Total Starch Assay (Amylglucosidase/alpha-Amylase Method); AOAC Official Method 996.11, 

“Starch (Total) in Cereal Products, Amylglucosidase-alpha-Amylase Method”; AACC Method 76.13, “Total Starch 

Assay Procedure (Megazyme Amyloglucosidase/alpha-Amylase Method)”
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There are several possible combinations of system boundaries and analytical methods that could be

used to perform a mass balance accounting of cellulosic conversion, which would offer the data needed 

to calculate the corresponding cellulosic biofuel production via an in situ process. Thus, there are

different ways to obtain the data to be used to calculate the CF values need to perform RIN allocation. 

We will present an example of how to use data characterizing feedstock composition, cellulosic 

conversion and certain process parameters to allocate RINs. In this example we assume that an in situ

process is simultaneously processing corn starch and cellulosic polysaccharides associated with corn 

kernel fiber to produce ethanol.

Data characterizing the corn composition (Table 1) and process specific data to elucidate the relative 

starch and cellulosic converted fraction (CF) will be required to appropriately allocate RINs. For this 

example, the validation protocol for obtaining the cellulosic CF requires performing an analytic process 

that involves 1) removing starch, 2) quantifying an initial level of cellulosic polysaccharides prior to 

hydrolysis, 3) quantifying a final level of cellulosic polysaccharides following hydrolysis, and 4) 

identifying the cellulosic ethanol by calculating the difference between the initial and final levels of 

cellulosic polysaccharides. In this example, the CF is determined to be the identified cellulosic ethanol 

(Step 4) divided by the theoretical ethanol yield for the total initial amount of cellulosic polysaccharides. 

Once the amount of ethanol resulting from the cellulosic polysaccharides has been identified, data 

characterizing the combined feedstock composition can be used to identify the cellulosic portion of the 

feedstock. An analysis of a representative sample of the feedstock would be used to characterize the 

corn composition (Table 1). Feedstock characteristics (Table 1), accurate CF values for cellulosic and noncellulosic conversion, and the total volume (cellulosic plus non-cellulosic volume) can be used to allocate 

RINs for the example batch (Table 2).

Table 1 – Relevant feedstock characteristics and composition

Corn Composition

Kernel Mass (M), lb wet 61.2 lb/bu

Corn Moisture (m), % wet 15%

Kernel Mass, lb dry 52.0 lb/bu

Starch, % of kernel dry 75.0%

Cellulosic polysaccharides, % of kernel dry 4.0%

 

RIN allocation for the cellulosic and non-cellulosic portions of the biofuel can be performed by applying 

the RIN volume (VRIN ) equation.

 =  ∙  ∙



 + 

Where EV is the equivalence value for the renewable fuel (in this case it is 1 since the fuel is ethanol), VS

is the standardized volume of the renewable fuel produced, and FE is the feedstock energy value. Note 
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that this equation will be applied separately to calculate the RIN volume for each D-code. The feedstock 

energy (FE) is characterized by the FE equation.

 =  ∙ (1 − ) ∙  ∙ 

Where M is the mass of the feedstock, m is the feedstock moisture content, CF is the converted fraction

and E is the energy content of the components of the feedstock converted to fuel (Table 2). 

Table 2 – Example: assumed inputs, intermediate values, and calculations

Example in situ RIN Allocation Calculation

Assumed feedstock for example (M), lb wet

Total standardized volume of fuel (VS), gal

1,000,000

64,158 Note: 77,000 Btu/gal ethanol

Starch Cellulose Comments

Feedstock, thousand lb dry / batch 637.5 34

Account for moisture content 

and composition (Table 1).

Energy Content (E), Btu/lb dry 7,600 7,600

Theoretical feedstock energy 

assuming complete conversion12.

Converted Fraction (CF) 0.95 0.35

Calculated using method

approved at registration13.

Feedstock Energy (FE), thousand Btu 4,602,750 90,440

Obtained by multiplying the dry 

feedstock, E, and CF.

RIN Volume (VRIN), gallons 62,922 1,236

Number of D6 and D3 RINs that 

would be assigned respectively 

for this example batch.

For the example presented, 1,000,000 pounds of wet corn feedstock was processed to produce 64,158 

gallons of ethanol. Based on the feedstock characteristics (determined using an appropriate analytical 

method as discussed previously) for the given reporting period, the wet feedstock was composed of 

637,500 pounds of starch and 34,000 pounds of cellulose on a dry mass basis. By establishing and using 

the dry mass of these components for subsequent calculation, the moisture content term in the FE

equation simplifies to 1. Multiplying the dry mass of each feedstock by its corresponding converted 

fraction (CF) and energy content (E) yields the feedstock energy (FE). Using the resulting FE values for 

starch and cellulose respectively, and applying the VRIN equation for allocating RIN volumes to batches 

with these two feedstocks yields the RIN volume for each type of D-code. Note that since the fuel

produced is ethanol, the energy equivalence value (EV) is 1.

 

12Energy content values (E) can be determined per the prescribed ASTM E 870 or ATME E 711 for gross calorific 

value methods (CFR 80.1426 (7) (v) (A). These default values for E are from CFR 80.1426 (7) (vi). 

13 CF values are typically an annual mass percent average, but for in situ processes generating D3 RINs, a new CF 

will have to be calculated for every 500,000 cellulosic RINs generated or every year – whichever comes first. The 

same CF is used for all RIN allocation between each required update.
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This example shows how information about the wet feedstock mass, total fuel output, feedstock 

characteristics, and calculated process parameters can be used to allocate separate RINs for an in situ

process converting both starch and cellulose to ethanol.