1 MEMORANDUM

TO: Hillary Ward, U.S. Environmental Prot ection Agency, OAQPS/Sector Policies and Programs Division, Fuel and Incineration Group



### FROM: Eastern Research Group, Inc. (ERG)

DATE: April 2014

SUBJECT: Methodology for Estimating Cost and Emi ssion Impacts of MSW Landfill Regulations

Introduction

The EPA is reviewing the new source performance standards (NSPS) for municipal solid waste (MSW) landfills and issuing an Advanced Notice of Proposed Rulemaking (ANPRM) for a review of the emission guidelines (EG) for MSW landfills (40 CFR part 60, subpart WWW and 40 CFR part 60, subpart Cc, respectively). Currently, the regulations require any landfills of at least 2.5 million megagrams (Mg) and 2.5 cubic meters in design cap acity with estimated nonmethane organic compounds (NMOC) emissions of at least 50 megagrams (Mg) per year to collect and control landfill gas (LFG). As part of the proposed revisions, a Microsoft ® Access database was developed to calculate the cost and emission impacts associated with varying certain cont rol parameters and applying these parameters to a dataset of existing and model future landfills. The development of the dataset is discussed in another
memorandum. 1 The purpose of this memorandum is to summarize the methodology for the evaluations.

1. General Assumptions

The emission reductions and costs associated w ith the requirements of the current rule are
considered the baseline and each alte rnative was compared to this b aseline. All existing landfills that accepted waste after November 1987 2 as well as future landfills that are predicted to open in the 5-year period of January 2014 through December 2018 are included in the analysis. Annual estimates of
emission reductions and costs were estimated for each landfill and alternative control scenario over the 10-year period (2014-2023) following the proposed revi sions to the NSPS. Costs were estimated using a 7 percent interest rate, which is consiste nt with EPA guidance for cost evaluations.

The alternatives differ from the baseline by variati ons in the emission rate thresholds, the design capacity thresholds, the initial lag time to install gas collection and control systems (GCCS), and the expansion lag time for GCCS. A description of each variable is presented below:

 The emission rate threshold in the current rule is 50 Mg per year NMOC. The alternatives
include lower NMOC thresholds.

1 ERG. 2014. Summary of Landfill Dataset Used in th e Cost and Emission Analysis of Landfill Regulations

2 The designated facility under the EG is each existing MS W landfill that has accepted waste since November 8,
1987.2  The design capacity threshold in the current rule is 2.5 million Mg and 2.5 cubic meters. Other landfill design capacity thresholds were evaluated as alternatives.

 The initial lag time is the time period between when th e landfill exceeds the emission threshold and when GCCS are required to be installed. Th e current rule allows a 30-month initial lag time, which was modeled as a 3-year lag time since th e first-order decay equation used to model emissions is on an annual, instead of monthly, basis. Further, because th e current rule requires annual NMOC emission reports to be submitted by 6 months into the following calendar year, the landfill would get 30 months afte r the submittal of its first NMOC emission report showing an exceedance to install the GCCS, which is appr oximately 36 months after the excess emissions occurred. Shorter initial lag times were examined among the alternatives.

 The expansion lag time is the amount of time allotted for the landfill to expand the GCCS into waste being placed in new areas of the landfill. The current rule allows 2 years after initial waste placement in closed areas and 5 years after initia l waste placement in active areas of the landfill; so the actual lag time varies by landfill dependi ng how quickly expansion areas are filled and closed. Based on input received during public out reach, most modern large landfills do not reach final grade within 2 years and a majority of la ndfills are complying with the 5 year provision. Therefore, a 4-year expansion lag time was assu med to represent the baseline. A shorter lag time
was examined as an alternative.

2. Estimating Emission Impacts

2.1 Waste Estimates

First, the quantity of waste maintained in each la ndfill was estimated for each year of the analysis,
based on one of two methods:
1. When a landfill’s annual waste acceptance rate (WAR) and waste in place (WIP) values were
available in the landfill dataset and associated with a particular year, those values were extrapolated to estimate the landfill’s WAR and WIP for each year. This estimation method was designated Option A in the database tabl e of Calculated Inputs_Annual Waste

 When a Landfill_WIP and Landfill_WIP_Y ear are reported, the WAR up until the
Landfill_WIP_Year is estimated base d on the following relationship: WAR = Landfill_WIP / (Landfill_WIP_Ye ar - Landfill _Year_Open+1).

 The WAR after the Landfill_WIP_Year is based on the following relationship: WAR = (Landfill_Design_Cap_tons - Landfill _WIP) / (Landfill_Closure_Year - Landfill _WIP_Year+1).

2. When WIP and WAR values were not availabl e in the landfill dataset, the annual WAR was estimated using the landfill open and closure years and the landfill capacity and assuming a

constant WAR over the lifetime of the landfill. This estimation method was designated Option D in the database table of Calculated Inputs_Annual Waste.

 WAR = Landfill_Design_Cap_tons / (Landfill_Cl osure_Year - Landfill _Year_Open+1) Next, the annual WIP was calculated by summing the WAR over time. The EPA is aware of historical WAR data from GHGRP, and it plans to incorporate these data in a future iteration of the model. The EPA also noted that some respondents to the voluntary survey provided historical waste acceptance rates that will be consider ed in the next iteration of the analysis.
2.3 2.2 Emission Equations

After the annual quantity of waste was estimated for each landfill, a first order decay equation (Equation 1) was used estimate annual methane em issions from each landfill for each year during the period of 2014-2023.

Eq. 1 : kt 0 t 4 e M L k CH     

Where:
CH 4t = Methane, ft 3 in year t k = Methane generation rate, year -1

L 0 = Potential methane generation capacity, ft 3 methane per ton M = Mass of waste accepted in year t, tons t = Analysis year (year 1 through 50), year The volume of LFG produced by a landfill was estimated using Equation 2.

Eq. 2 : LFG t = CH 4t × 2

Where:
LFG t = Landfill gas, ft 3 in year t
CH 4t = Methane, ft 3 in year t 2 = Multiplier to convert methane to LFG (assuming that LFG is 50 percent methane), unitless

The mass of NMOC emissions produced by each landfill was estimated based on the amount of LFG produced at the landfill, as shown in Equation 3.

Eq. 3 : NMOC t = LFG t ÷ 35.32 × 595 × 3.6E -9

Where:
NMOC t = NMOC in year t, Mg in year t
LFG t = Landfill gas, ft 3 in year t 35.32 = Conversion, ft 3 per m 3 595 = Concentration of NMOC in LFG, ppm NMOC by volume as hexane 3.6E-9 = Conversion factor, Mg NMOC per m 3 LFG

The mass of methane emissions produced by each landfill was estimated based on the volume of methane produced at the landfill, as shown in Equation 4a.

Eq. 4a : Mg CH 4 = CH 4t × 0.0423 ÷ 2000 ÷ 0.90718

Where: Mg CH 4 = Methane in year t, Mg in year t
CH 4t = Methane, ft 3 in year t (From Equation 1) 0.0423 = Density of methane, lb per ft 3 2000 = Conversion, lb per short ton 0.90718 = Conversion, short ton per Mg4 The mass of methane emissions, in terms of carbon dioxide equivalents, produced by each landfill was estimated using the Equation 4b.

Eq. 4b : Mg CO 2 eq = Mg CH 4 × GWP CH4

Where: Mg CO 2 eq t = Methane emissions as carbon dioxide equivalents, Mg in year t Mg CH 4t = Methane, Mg in year t (From Equation 4a)
GWP CH4 = 25, Global Warming Potential of Methane

2.3 NSPS/EG and AP-42 Default Values for Calculating Emissions 3

The current NSPS requires the use of Tier 1 defa ult value for the potential methane generation capacity (L 0 ) and methane generation rate (k) to determ ine when the landfill exceeds the 50 Mg NMOC per year emission rate threshold. The NSPS L 0 is equal to 5458 ft 3 methane per ton of waste and the NSPS k values are 0.05 per year for areas receiving 25 inches or more of rainfall per year and 0.02 per year for areas receiving less than 25 inches of rainfall. While th e NSPS offers a conservatively high Tier 1 default NMOC concentration, the regulations allow the use of Tier 2 tests to determine NMOC concentration. (Many landfills have conducted Tier 2 tests and gotte n values that are consistent with the AP-42 average NMOC concentration of 595 ppmv.) Therefore, the combination of the Tier 1 defaults for k and L 0 and the NMOC concentration of 595 ppmv were used to represent how landfills currently calculate NMOC emissions to determine if they have to install c ontrols under the NSPS. Because the use of these values
result in estimates of LFG and NMOC that are in acc ordance with the current NSPS; in this evaluation
these estimates were called LFG NSPS/EG and NMOC NSPS/EG . NSPS defaults tend to overestimate actual emissions at most landfills (due to the conservatively high L 0 and k values). EPA has collected and compiled available emission factor data for landfills in the report Compilation of Air Pollutant Emission Factors (AP-42). 4 The AP-42 L 0 is equal to 3210 ft 3 methane per ton of waste. The AP-42 k values are 0.04 per year for areas receiving 25 inches or more of rainfall per year and 0.02 per year for areas receiving less than 25 inches of rainfall. The use of these values, in combination with the NMOC concentration of 595 pp mv, result in estimates of LFG and NMOC that are in accordance with the AP-42; in this evaluation these estimates were called LFG AP-42 and NMOC AP-42

.

As previously mentioned, for this evaluation, LFG NSPS/EG and NMOC NSPS/EG were used to
determine when landfills would inst all controls. To determine when landfills may remove controls, the
current rules allow landfills to measure the actual co llected gas flow rate as well as the concentration (instead of relying on Tier 1 default L 0 and k defaults). Because the AP-42 values for L 0 and k produce results that more closely match actual gas flow rates and emissions, LFG AP-42 and NMOC AP-42 were used in this analysis to determine wh en landfills would remove controls.

Landfill-Specific k Factors

As noted above, the k values depend on the amount of precipitation at the landfill. For this evaluation, precipitation data by climate divi sion from the National Oceanic and Atmospheric Administration (NOAA) were obtained and av eraged over the period of 2000 to 2009. 5 These average

3 The modeling requirements for existing sources under the state and federal plans implementing the EG are similar
to those for new sources under the current NSPS.

4 USEPA AP-42, Fifth Edition, Volume I Chapter 2: Solid Waste Disposal.

http://www.epa.gov/ttn/chief/ap42/ch02/index.html

5 NOAA climate division data are available online a t: http://www7.ncdc.noaa.gov/CDO/CDODivisionalSelect.jsp#

and are available for download at ftp://ftp.ncdc.noaa.gov/pub/data/cirs

.5 precipitation factors of each climate division were ma tched to the county-level location of each landfill. The k factors were assigned to each landfill based on the resulting amount of precipitation at each landfill.

2.4 Emission Reductions

To estimate emission reductions, the amount of LFG, methane and NMOC emitted at each landfill was estimated using the equations in Section 2.1. After the emissions at each landfill exceed the
NMOC emission rate threshold of each control scenar io, the model assumed that the collection equipment was installed and operational at the landfill after the in itial lag time of the control scenario. For example,
if the landfill exceeded the NMOC emission threshold in year 1, and the initial lag time was 3 years, the landfill would begin collecting gas in year 4. As the landfill was filled over time, the model assumed the landfill would expand the GCCS into new areas of w aste placement in accordance with the expansion lag time of the control scenario. If the landfill was not expa nding the gas collection system (i.e., by installing wells in new areas of waste placement) every year, the landfill may have produced more emissions than could be collected until the gas collection system was expanded.

Once the landfill reached the maximum gas productio n and the gas production started to decrease, the analysis assumed that the GCCS would collect a ll of the emitted gas. To determine the amount of LFG, methane and NMOC collected, the analysis used the LFG AP-42 and NMOC AP-42, estimates with the appropriate lag times. This was the best estimate of actual gas collected. See Table 1 for an example of the collected gas estimate at a la ndfill where the initial lag time was 3 years and the expansion lag time was 4 years.

Table 1. Example of Collected NMOC Estimate at a Landfill with an Initial Lag Time of 3 Years and an Expansion Lag Time of 4 Years

Year NMOC NSPS/EG NMOC AP-42 Collected NMOC

1 50.2 27.7 0.0

2 50.4 27.9 0.0

3 50.6 28.0 0.0

4 50.8 28.2 28.2

5 51.0 28.3 28.2

6 51.1 28.5 28.2

7 51.3 28.6 28.2

8 51.5 28.7 28.7

9 51.6 28.9 28.7

10 51.7 29.0 28.7

11 51.9 29.1 28.7

12 52.0 29.2 29.2

13 52.1 29.3 29.2
14 52.2 29.4 29.2

15 52.3 29.5 29.2

The emission reductions are equal to the amount of collected NMOC and methane that is combusted. The amount of collected NMOC and methane destroyed by combustion controls was estimated by multiplying the amount of collected gas by a destruction efficiency of 98 percent. The 98 percent destruction efficiency accounts for the fact that combustion is not 100 percent efficient.

3. Cost Equations

The cost equations used in this regulatory evaluation were derived from EPA’s Landfill Gas Energy Cost Model (LFGcost), version 2.3, whic h was developed by EPA’s Landfill Methane Outreach Program (LMOP). LFGcost estimates costs for gas collection, flare and energy recovery systems and was6 developed based on cost data obtained from equipment vendors and consulting firm s that have installed and operated numerous gas collecti on and control systems. LFGcost encompasses the types of costs included in the EPA Office of Air Quality Planni ng and Standards (OAQPS) control cost manual including capital costs, annual costs, and r ecovery credits. Total capital costs include purchased equipment costs, installation costs, engineering and de sign costs, costs for site preparation and buildings, costs of permits and fees, and working capital. Total annual costs include direct costs, indirect costs, and recovery credits. Direct annual costs are those that are proportional to a facility-specific metrics such as the facility’s productive output or size. Indirect annua l costs are independent of facility-specific metrics and may include categories such as administrative charg es, taxes, or insurance. Recovery credits are for materials or energy recovered by the control system.

For this evaluation, all costs are presented in 2012$. The costs included in LFGcost are in 2008$ and were escalated to 2012$ using an escalation factor of 1 percent for capital costs and 2.5 percent for
O&M costs.

The analysis presents the annuali zed capital cost of flares, wells, wellheads (including piping to collect gas) and engines over the lifetime of the e quipment. It was assumed that the equipment would be replaced when its lifetime was over, so the annuali zed capital costs were incurred as long as the landfill still had controls in place. In order to calculate the annualization factors, it was assumed that flares, wells, well heads, and engines had a 15-year lifetime. In add ition, there was a mobilization/installation charge to bring well drilling equipment on site each time the gas collection system was expanded. Because the landfill would be drilling wells to expand the control system during the expansion lag year, it was assumed that this capital installation cost had a lifetime equal to the expansion lag time.

A number of the capital costs equations depend on the number of wells at each landfill. In order to estimate the number of wells at each landfill, the nu mber of acres that have been filled with waste for each landfill for each year were estimated. It was assu med that the percent of design area filled (acres) would track the ratio of waste in place/design capacity (e.g., if a landfill had a waste-in-place amount equivalent to 40 percent of design capacity, then 40 pe rcent of the planned acreage would be filled). In addition, it was assumed that each landfill would inst all one well per acre, consistent with the guidelines provided in the LFGcost model, and that the num ber of wells would increase periodically based on expansion lag time. See Table 2 for an example of the number of wells estimated annually at a landfill where the initial lag time is 3 years and the expansion lag time is 4 years.

Table 2. Example of Number of Wells at a Landfill with an Initial Lag Time of 3 Years and an Expansion Lag Time Equal to 4 Years (and the landf ill reaches the emission rate threshold in year 1)

Year Acreage Number of Wells

1 98.2 0

2 102.9 0

3 107.5 0

4 112.1 112

5 116.8 112

6 121.4 112

7 126.1 112

8 130.7 131
9 135.4 131

10 140 131

11 140 131

12 140 140

13 140 1407 Year Acreage Number of Wells

14 140 140

15 140 140

3.1 Capital Costs

The equations used in this evaluation to cal culate capital costs for flares, wells, wellheads (including gas collection piping), mobilization/insta llation, and engines are presented below. All costs equations are shown on an individual landfill and year basis.

Flare Capital Costs

Flares are the primary control device used at la ndfills. All landfills required to comply with the
control scenario were assumed to in stall flares; even landfills using engines would have flares as the backup control device for periods when the engines are no t operating. The capital flare costs were estimated using the equation below, which was based on the insta lled cost of the knockout, blower, and flare system
as determined in LFGcost. The flares were sized ba sed on the maximum LFG flow rate over the 15-year flare lifetime, which could be as late as 2037 for projec ts that were expected to begin operation in 2023.

Eq. 5 : 4 61

. 0

max 15yr

y 15, capital ) 01

. 1 ( 100

, 4 525,600 LFG

z Flare          

 

Where:
Flare capital = Installed annualized cost of knockout, blower, and flare system, 2012$

z 15,y = Annualization factor where x=15 yrs and y=interest rate (0.07), unitless
LFG 15yrmax = Maximum LFG collected for 15 year project period, ft 3 per year 525,600 = Conversion factor, minutes per year $4,100 = Installed capital cost of knockout, blower, and flare system, 2008$ per

ft 3 /min LFG (1.01) 4 = Adjustment from 2008$ to 2012$, unitless 6

Well Capital Costs

The well capital costs were based on a dollar per foot of well depth installed estimate from LFGcost. As shown in the equation below, wells were assumed to have a depth of 10 feet less than the landfill depth. The method used to estimate the numbe r of wells at the landfill each year is described
above.

Eq. 6 : Well capital = z 15,y × (Depth – 10) × 90 × Wells annual × (1.01) 4

Where:
Well capital = Installed annualized cost of wells, 2012$

z 15,y = Annualization factor where x=15 yrs and y=interest rate (0.07), unitless Depth = Landfill waste depth, feet
10 = feet $90 = Installed capital cost of one well, 2008$ per foot of well depth

6 Escalation equation uses a formula of (1+escalation/100) t , where capital cost escalation is assumed to be 1 percent

and t is equal to 4 years8 Wells annual = Number of wells operated each year (1.01) 4 = Adjustment from 2008$ to 2012$, unitless

Wellhead Capital Costs

The capital wellhead cost covered the equipmen t associated with each well, including the wellhead and gathering lines (and associated sumps) connecting the wells, and was dependent on the number of wells. The capital wellhead costs at each landfill were estimated using a dollar per wellhead
installed cost from LFGcost and the number of wells at each landfill.

Eq. 7 : Wellhead capital = z 15,y × 15,000 × Wells annual × (1.01) 4

Where:
Wellhead capital = Installed annualized cost of wellheads, 2012$

z 15,y = Annualization factor where x=15 yrs and y=interest rate (0.07), unitless $15,000 = Installed capital cost of one wellhead, 2008$ per well

Wells annual = Number of wells operated each year (1.01) 4 = Adjustment from 2008$ to 2012$, unitless

Mobilization/ Installation Costs for Wellfield Expansion

The cost occurs each time the gas collection sy stem (i.e., wellfield) was expanded into new areas of the landfill, so the frequency was dependent on the expansion lag time. This cost was independent of the number of wells being added. It included costs su ch as planning and set-up, mobilization costs to get the well drilling rig on site, and limited engineering/mana gement costs. This cost was estimated using the following equation:

Eq. 8 : Installation capital = z x,y × 25,000 × (1.01) 4

Where:
Installation capital = Mobilization/installation annualized cost, 2012$

z x,y = Annualization factor where x=expansion lag time in yrs and y=interest rate (0.07), unitless $25,000 = Mobilization/Installation costs, per occurrence, 2008$ (1.01) 4 = Adjustment from 2008$ to 2012$, unitless

Engine Capital Costs

Engines were assumed to be installed only at la ndfills that produced enough LFG to power the engine and only when the electricity buyback rates al lowed the operation of the engine to be profitable. Standard engines used at landfills have approxima tely 1 MW capacity, which equates to 195 million ft 3 per year of collected LFG (at 50 percent methane). Th erefore, engines were assumed to be installed at
landfills that had at least 195 million ft 3 per year of collected LFG for at least 15 years, which could be as late as 2037 for engines there were installed in 2023.

The engine capital and operation and maintena nce (O&M) equations were calculated and summed to determine at what electricity buyback rate an engine would be profitable. The profitable electricity buyback rate was greater than $0.0457 pe r kWh at 7 percent interest. It was assumed engines were only installed in states with bu yback rates exceeding those values.9 Multiple engines may be present at a landfill wh en there is sufficient gas flow to support additional engines. As noted above , one engine required 195 million ft 3 per year of collected LFG. To have two engines on site, the landfill must ha ve had double that amount of LFG (390 million ft 3 per year) for at least 15 years after the project start date, which could be as late as 2037 for projects starting in
2023.

The capital costs for engines were based on the cap ital costs for standard reciprocating enginegenerator sets in LFGcost. These costs included gas compression and treatment to remove particulates and moisture (e.g., a chiller), reciprocating engine a nd generator, electrical interconnect equipment, and site work including housings, utilities, and total facility engi neering, design, and permitting.

Eq. 9 : Engine capital = z 15,y × 1,850,000 × (1.01) 4 × Engine multiplier

Where: Engine capital = Installed annualized cost of engines, 2012$

z 15,y = Annualization factor where x=15 yrs and y=interest rate (0.07), unitless $1,850,000 = Installed capital cost of one reciprocating engine-generator set, 2008$ per engine (1.01) 4 = Adjustment from 2008$ to 2012$, unitless Engine multiplier = Number of engines needed

3.2 Operation and Maintenance (O&M) Costs

The equations used in this evaluation to calcula te O&M costs for flares, wells, electricity, and engines are presented below. All cost equations are shown on an individual land fill and year basis. These costs for all landfills were summed by year and the resulting annual sums were used to estimate NPV

costs. To accurately estimate annual electricity costs a nd engine revenue from the generation and sale of electricity, two electricity prices were needed. Landfil ls must purchase electricity to operate the blowers
used to collect LFG. EPA used comme rcial average retail electricity prices by State from the U.S. Energy
Information Administration to estimate el ectricity purchase prices at the landfill.

Landfills utilizing engines generate revenue from the sale of the LFG-produced electricity. The amount of revenue generate d depends primarily on the buyback ra te negotiated between the landfill (or third party developer) and the electric company purchasing the LFG-generated power. Average (mean) wholesale prices for each state from the U.S. Energy Information Administration (EIA) were used to estimate electricity buyback rates 7 . These wholesale prices generally fit in the range of typical buyback prices for LFG of $0.025 - $0.07/kWh, as discussed in LMOP’s Project Development Handbook. Additionally, LFGcost uses a default buyback rate of $0.06/kWh and the U.S. average of the wholesale prices used is $0.058/kWh.

EIA wholesale data were not available for th ree States (HI, RI & WV). For these States, electricity purchase price data from EIA were used to estimate buyback rates. 8 The buyback rates were estimated by first determining the ratio of each State’s purchase price to the overall average U.S. purchase. This ratio was then multiplied by the calcula ted average U.S. whole price to estimate a buyback

7 U.S. DOE/EIA. Form EIA-861 Database . Final Data File for 2009 (File 1.xls). http://www.eia.doe.gov/cneaf/electricity/page/eia861.html

8 U.S. DOE/EIA. Electric Sales, Revenue, and Average Pr ice 2009. Table 4. Average Retail Price for Bundled and Unbundled Consumers by Sector, Census Division, and State, 2009. Nov 2010. http://www.eia.doe.gov/electricity/esr/table4.html10 rate. Electricity price data for the U.S. territories of Guam, Puerto Rico, and the Virgin Islands were not found. Therefore, an LFGcost scenario was created using economic inputs expected on an island to estimate a buyback rate of $0.12/kWh utilized by all three territories.

Flare O&M Costs

An estimate of the flare O&M costs from LFGcost was used to estimate th e flare annual costs, as shown in the equation below:

Eq. 10 : Flare O&M = 4,500 × (1.025) 4

Where:
Flare O&Ml = Flare annual O&M costs, 2012$ $4,500 = Annual O&M flare cost, 2008$ (1.025) 4 = Adjustment from 2008$ to 2012$, unitless 9

Well O&M Costs

An estimate of the well O&M costs from LFGcost was used to estimate the well annual costs, as shown in the equation below:

Eq. 11 : Well O&M = 2,250 × Wells annual × (1.025) 4

Where:
Well O&Ml = Well annual O&M costs, 2012$ $2,250 = Annual O&M well costs, 2008$ per well

Wells annual = Number of wells operating each year (1.025) 4 = Adjustment from 2008$ to 2012$, unitless

Electricity O&M Costs

The electricity cost of operating the blowers was ca lculated using the electricity usage of blowers and the electricity purchase price.

Eq. 12 : Electricity O&M = 0.002 × Electricity purchase × LFG collected

Where: Electricity O&M = Electricity annual O&M costs, 2012$ 0.002 = Electricity usage by blowers, kWh per ft 3 LFG Electricity purchase = Electricity purchase price, 2012$ per kWh

LFG collected = Amount of LFG collected, ft 3 per year

Engine O&M Costs

For landfills with engines installed, the O&M cost s of the engine were estimated using the annual costs for standard reciprocating engine-generator sets from LFGcost, and taking into account the amount of time that the engine was operating each year and the number of engines on site.

9 Escalation equation uses a formula of (1+escalation/100) t , where O&M cost escalation is assumed to be 2.5

percent and t is equal to 4 years.11 Eq. 13 : Engine O&M = 0.02 × 1,000 × 8,760 × 0.93 × (1.025) 4 × Engine multiplier

Where: Engine O&M = Engine annual O&M costs, 2012$ 0.02 = Annual O&M engine cost, 2008$ per kWh 1,000 = Amount of electricity as kW produced by a 1 MW engine, kW per engine 8,760 = Conversion factor, hours per year
0.93 = Fraction of time that the engine is online, unitless (1.025) 4 = Adjustment from 2008$ to 2012$, unitless Engine multiplier = Number of engines

Engine Revenue Costs

For landfills with engines installed, the revenue of the electricity produced by the engines was calculated using the equation below. This equation assumed that all electricity generated was sold to the grid (instead of some of the electricity generated being used to power the GCCS).

Eq. 14 : Engine

revenue = 1,000 × 8,760 × 0.93 × Electricity buyback × Engine multiplier

Where: Engine

revenue = Engine annual revenue, 2012$ 1,000 = Amount of electricity as kW produced by a 1 MW engine, kW per engine 8,760 = Conversion factor, hours per year
0.93 = Fraction of time that the engine is online, unitless Electricity buyback = Electricity buyback rate, 2012$ per KWh Engine multiplier = Number of engines

4. Summary

This memorandum summarizes the emission reduction and cost equations used to evaluate the cost and emission impacts of various control scenario s considered under the review of the NSPS and EG. The EPA determined which landfills met the design capacity and emission rate thresholds for each regulatory option, then calculated the emission reduc tions and costs for each landfill for each year from 2014 through 2023 under each control scenario using the equations described in this memorandum. The results of applying this methodology to the landfills dataset are discussed in other memoranda and are
detailed in the database. 10, 11, 12, 13

10 ERG. 2014. Cost and Emissions Impacts Resulting from the La ndfills NSPS Review.

11 ERG. 2014. Modeling Database Containing Inputs and Results of Proposed Revisions to MSW Landfill NSPS.

12 ERG. 2014. Preliminary Cost and Emissions Impacts Analysis for Review of the MSW Landfills Emission
Guidelines.

13 ERG. 2014. Modeling Database Containing Inputs an d Preliminary Impacts for Re view of the MSW Landfill
Emission Guidelines.