MEMORANDUM

Subject:	Analysis of the Types of Engines Used to Estimate the CAA
Section 112(k) Area Source Inventory for Stationary Reciprocating
Internal Combustion Engines

From:		Melanie King, Energy Strategies Group

To:		EPA Docket EPA-HQ-OAR-2008-0708

Date:		January 5, 2010

Section 112(c)(3) of the Clean Air Act (CAA) requires that EPA list
categories or subcategories of area sources sufficient to ensure that
area sources representing 90 percent of the area source emissions of the
30 HAP that present the greatest threat to public health in the largest
number of urban areas are regulated.  EPA listed the stationary
reciprocating internal combustion engine area source category under
112(c)(3) and (k) as one of the categories needed to ensure that 90
percent of such area source emissions are regulated.  In response to
comments received on the proposed NESHAP for existing stationary RICE
located at area sources (74 FR 9697), EPA analyzed the types of engines
that were included in the area source category listing for stationary
RICE.  As a result of this analysis, EPA determined that emissions from
existing stationary emergency engines located at residential,
commercial, and institutional facilities were not included in the 1990
baseline emissions inventory that was used as the basis for the listing
of source categories needed to ensure that 90 percent of area source
emissions are regulated.  Residential, commercial,and institutional
emergency stationary RICE include emergency stationary RICE used in
residential establishments such as homes or residences, commercial
establishments such as office buildings, hotels, or stores, or
institutional establishments such as medical centers, research centers,
and institutions of higher education.  Therefore, EPA determined that
these engines at these locations will not be subject to this area source
standard.  A detailed description of the analysis to determine the
engines that were the basis for the inventory is provided below.

Summary of the information used in estimating the 1990 112(k) Area
Source Inventory for Stationary RICE

The emissions for stationary RICE used to estimate the 1990 112(k) area
source inventory were calculated using national estimates for fuel
consumption (in units of  J/yr) of natural gas and distillate oil for
engines used for two purposes:

1) engines used by utilities for electricity generation  

2) engines used in industrial applications

EPA extrapolated fuel consumption information for the year 1990 from
estimates of consumption for the years 1978 and 1985 in an EPA report
(Reference 1).  The 1990 fuel consumption estimates were multiplied by a
J/Btu conversion and then multiplied by a lb/MMBtu emission factor in
order to determine the tons emitted per year for each HAP.  This was
done for each fuel type (natural gas and distillate oil). 

The EPA report does not have any further description of what type of
engines are included in the fuel consumption data.  The EPA-RTP Library
was able to obtain some of the references for the fuel consumption data.
 None of the references have any information on what size of engines are
included.  The primary references for the 1978/1985 data for the engines
used by utilities for electricity generation do not provide any
additional detail about what engines are included.  The reference for
the 1978 data for the engines used in industrial applications indicates
that the data is for engines used for the following applications:     

oil and gas pipelines 

natural gas processing plants

oil and gas exploration

crude oil production

natural gas production

agricultural

industrial process

municipal water and sewage

The Library was unable to obtain the reference for the 1985 data for
industrial application engines.  

Detailed description of fuel consumption data

The fuel consumption numbers that were used are shown in Table 1.  The
1978 and 1985 fuel consumption data were obtained from Reference 1.  EPA
extrapolated the estimates for 1990 from the 1978 and 1985 estimates.  

Table - Fuel consumption (1015 J/yr) for stationary reciprocating
engines

Year	Engines used for electricity generation	Engines used in industrial
applications

	Natural Gas	Distillate Oil	Natural Gas	Distillate Oil

1978	25a	31a	1004d	62d

1985	15b	43b	1093e	73e

1990	26c	34c	1171f	72f

aThe 1978 fuel consumption numbers were determined by subtracting
National Electric Reliability Council (NERC) estimates of 1976 fuel
consumption for utility turbines (Reference 2) from Federal Power
Commission (FPC) data for 1976 fuel consumption by internal combustion
plants owned by utilities (Reference 3).  The 1978 fuel consumption for
electricity generation reciprocating engines was assumed to be equal to
the 1976 numbers “as reciprocating engine generating capacity for the
two years are about equal.” 

bThe 1985 fuel consumption estimates for reciprocating engines used by
utilities for electricity generation were determined using NERC
estimated fuel requirements for 1985 (Reference 2).  The NERC estimates
were for fuel consumption for combustion turbines.  The 1985 estimates
were a 40.8% decrease in fuel consumption for gas-fueled turbines from
the 1978 figures.  The EPA report estimated that the fuel consumption
for natural gas-fired engines would decrease by the same percentage as
for turbines (40.8%).  Based on estimates from the FPC (Reference 4),
the EPA report estimated that the total diesel engine capacity would
increase by 2.1% from 1976-1985.  The fuel consumption for
distillate-fired engines would therefore increase by 37.2% from 1978 to
1985 due to the increased capacity and the decreased consumption of
natural gas.

cThe 1990 consumption estimates were “assumed” by Fred Porter of EPA
and it doesn’t say how he “assumed” those numbers.

dThe 1978 fuel consumption data for industrial engines was estimated
from 1971 fuel consumption data from an EPA report (Reference 5) and the
ratios of domestic natural gas and crude oil production figures for
those two years (References 6-8).  The 1971 fuel consumption data was
for engines used in the following applications:

Application	Engine uses listed for application

Oil and gas pipelines



	Natural gas processing plants	drive gas compressors and refrigeration
compressors

Oil and gas exploration	drive electric generators, drawworks, drilling
mud pumps, rotary drilling rigs

Crude oil production	drive beam pumps, gas lift compressors, hydraulic
pump power pumps

Natural gas production	drive repressuring compressors

Agricultural

	drive agricultural water pumps

Industrial process

	drive industrial process equipment and plant air compressors

Municipal water and sewage

	drive municipal water and sewage pumps



eProjected 1985 fuel consumption rates for industrial internal
combustion sources were estimated based on 1985 domestic natural gas and
crude oil supply rates from the Federal Energy Administration (Reference
8).  Assumptions used are that fuel consumption rates are proportional
to domestic natural gas production and that fuel consumption rates for
distillate oil fueled engines are proportional to domestic crude oil
production.  Exception is that fuel consumed by gas reciprocating
engines for crude oil production is assumed to be proportional to the
domestic crude oil production rate.

fFuel consumption for 1990 was extrapolated for industrial engines
assuming that the growth rate in fuel consumption from 1978 to 1985 was
the same as the growth rate from 1985 to 1990.  A compound growth rate
was assumed.  Distribution between gas and oil fired engines was assumed
to be the same in 1990 as in 1978.

References

Emissions Assessment of Conventional Stationary Combustion Systems:
Volume II.  Internal Combustion Sources.  EPA-600/7-79-029c.  February
1979.

Fossil and Nuclear Fuel for Electric Utility Generation Requirements and
Constraints.  1977-1986.  National Electric Reliability Council,
Princeton, New Jersey.  August 1977.

FPC News Release No. 23009.  Federal Power Commission, Washington, D.C. 
March 25, 1977.

FPC News Release No. 22673.  Federal Power Commission, Washington, D.C. 
October 15, 1976.

McGowin, C.R.  Stationary Internal Combustion Engines in the United
States.  Report prepared by the Shell Development Co. for the U.S.
Environmental Protection Agency.  EPA Report No. R2-73-210.  April 1973.
 120 p.  NTIS PB-221 457.

1974 Gas Facts.  American Gas Association.  Arlington, VA.  1975.  

Dupres, W.G., Jr. and J.S. Corsentino.  United States Energy through the
Year 2000 (Revised) Bureau of Mines, U.S. Department of the Interior. 
December 1975.

National Energy Outlook, Federal Energy Administration.  February 1976.

 1990 Emissions Inventory of Forty Potential Section 112(k) Pollutants,
Supporting Data for EPA’s Section 112(k) Regulatory Strategy.  May 21,
1999.

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