&EPA
United States	Air and Radiation Draft
Environmental Protection	6202J	November 1998
EPA Coalbed Methane Outreach Program Technical Options Series
ofiring Coal Mine Methane in Coal-Fired Utility and Industrial Boilers
Coal Stoker Boiler Equipped for Natural Gas Cofiring
(Photo Courtesy of Energy Systems Associates)
A Practical. Economical Use for Coal Mine
~	Reduces emissions of SO2, NOx, C02and methane (a potent greenhouse gas)
~	Reduces operating and maintenance costs, and improves stack opacity and ash quality
~	Ideal for medium-quality (below pipeline spec) gas that mines recover from gob areas
~	Commercially proven using conventional natural gas in the United States and elsewhere
~	Commercially proven with coal mine methane

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Cofiring is the
:ombustion of gas with
coal in the primary
combustion zone of a
coal-fired boiler
why Consider Cofiring Coal Mine Methane in Boilers?
Coal mine methane, like conventional natural gas, is an ideal boiler fuel because
it requires no storage or preparation for combustion. For years, gassy coal mines in
China, the Czech Republic, Poland, Russia, and Ukraine have taken advantage of
their abundant supply of methane by cofiring it with coal in their boilers to
produce heat and/or electricity. In addition to on-site use at the mine, mines can
pipe methane to nearby power plants or other industries for cofiring in their
boilers.
The benefits of coal
mine methane use in
coal boilers include
improved combustion
md boiler control, and
reduced pollution
The gas input to a boiler may vary from less than 10 percent to 100 percent of
total fuel input depending on boiler design, gas availability, and the needs of the
boiler operator. The required equipment is commercially available, meets all
applicable codes, and, in many cases, is already in place.
Because it contains no ash, virtually no sulfur, and is low in nitrogen, the firing of
coal mine methane in coal boilers reduces SO2, NOx, and particulate emissions.
These benefits are more important than ever before, because of new EPA
particulate emissions regulations. The improved combustion achieved with
cofiring can also improve carbon burnout and reduce opacity problems. Boiler
operators can inject coal mine methane into different areas of the boiler to
address a variety of boiler operational concerns, such as slag buildup. The ease
of boiler conversion and low capital cost of cofiring can represent a low-risk
approach to improving boiler performance. Coal-fired utility boilers in the U.S.
consumed more than 70 billion cubic feet of conventional natural gas in 1995.
These boilers used this gas for ignition, warm-up, and load carrying.
Many gassy coal mines are in close proximity to industrial boilers, and at least ten
gassy coal mines in the U.S. are within 20 miles of utility boilers. EPA's Coal Mine
Methane Outreach Program has prepared a report (available on request)
identifying several potential sites in the U.S. that could economically cofire coal
mine methane.
Cofiring Gas in Coal Boilers Can Result in...
•	Net Cost Savings - Low capital investment and rapid return on investment
•	Better Efficiency - Improved carbon burnout, lower excess air level
•	Reduced Emissions of NOx, SOx. particulates, CO2 and CPU (greenhouse gases)
•	Improved Operation - Easier startup, increased short-term peaking capacity
•	Lower Startup Costs compared to oil
•	Improved Ash Quality, making the ash a saleable commodity in many cases
Numerous gassy coal
mines in several
countries successfully
cofire methane in their
toilers to produce heat
and/or electricity
Economics of Cofiring Coal Mine Methane at a Coal Fired Power Plant
EPA analyzed the economics of cofiring coal mine methane in several coal-fired
power plants. A project in which 4 mmcf of methane per day replaces 3% of the
coal used in a 600 MW boiler located 17 miles from a mine would yield a net
present value (NPV) of more than $5 million and an internal rate of return (IRR) of
29%. These results are based on conservative cost estimates for gathering,
transportation, compression and boiler conversion. The model also recognizes
the economic benefits of NOx and SOx reduction achieved by cofiring methane.
If the same mine produces 6 mmcf of methane per day for use in the boiler, the
NPV is more than $10 million and the IRR is 44%. Economic benefits increase as
the volume of methane recoverable increases.

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Cofiring Zone
Combined
Coal and Natural
Gas Flames
Natural Gas
Combustion
OffiftireAir Sos Burpef c

h-h '..rnni

3T
lap View
Side View
Various types of boilers can cofire coal mine
methane, just as they would conventional
natural gas. Left, cofiring in a wall-fired utility
boiler. Above, cofiring in an industrial stoker
boiler.
(Illustrations from the Gas Research Institute
hrrmhi irp*c "Cnfirinn Crice* "s+i	Cr>mnp*+inn in n
The Gas Research Institute (GRI) has evaluated the use of cofiring at numerous utility and industrial
boilers. More than 370 utility boilers in the U.S. now have cofiring capability, and GRI and others
have documented the many benefits. The table below shows how the emission, operation, and
performance benefits of cofiring in three diverse cases - a municipal power plant, an institution, and
a manufacturing company- more than justify the cost.
Three Industrial Boiler Case Studies: Quantifiable Benefits
Industry/Institution Dover Light and Power Oberlin College 1 he Hoover Company
Boiler Type (all stoker)
1 7 MWe,
165,000 Ib/hr spreader
40,000 Ib/hr chain grate
75,000 Ib/hr chain
grate
% of Gas Cofired
8-15%
20%
40%
Benefits (Emissions
Reduction, Improved
Operation, Efficiency)
$0.29 / MmBtu
$1.67/MmBtu
$1.20/ MmBtu
Costs (Fuel Price
Increase, Annualized
Capital Cost)
$0.15 / MmBtu
$0.52 / MmBtu
$0.78 / MmBtu
Net Cost Savings
$0.14/MmBtu
$1.15/ MmBtu
$0.42 / MmBtu
Payback (simple)
1.4 years
1.8 years
3.1 years
Benefits Realized
•	Efficiency up 3-4%
•	Particulates down
33%
•	Recovered lost
capacity
•	Clean, fast light-off
•	Eliminated use of
separate boiler for
low steam demand
periods
•	Improved efficiency
•	Emissions
reductions
•	Load following
capability
•	Improved opacity
•	Gas-only startup
Cost data are approximations based on interpretation o
Cofiring".
: graphs from GRI brochure "industrial Boiler Gas

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For More	Infor
Utility plant operators, manufacturers, and institutions are seeking ways to cut costs, improve
performance, and comply with air quality regulations. Utilities and other industries recognize
the benefits of cofiring gas in coal-fired boilers, and the use of coal mine methane for this
purpose may be a profitable alternative to conventional natural gas.
To obtain more information about natural gas cofiring in utility boilers, contact:
John M. Pratapas
Principal Technology Development Manager
Gas Research Institute
8600 W. Bryn Mawr Ave.
Chicago, IL 60631-3562
(773) 399-8301
Fax: (773) 399-8170
email: jpratapa@gri.org
To obtain more information about natural gas cofiring in industrial boilers, contact:
Isaac Chan
GRI Project Manager
Industrial Business Unit
Gas Research Institute
8600 W. Bryn Mawr Ave.
Chicago, IL 60631-3562
(773) 399-5411
Fax: (773) 399-8170
Email: ichan@gri.org
Or contact EPA's Coalbed Methane Outreach Program for information about this and other profitable
uses for coal mine methane:
http://www.gri.org
Coalbed Methane Outreach Program
U.S. EPA
401 M Street, SW (6202J)
Washington, DC 20460 USA
(202) 564-9468 or (202) 564-9481
Fax: (202) 565-2077
e-mail:	fernandez.roger@epa.gov
schultz.karl@epa.gov
http://www.epa.gov/coalbed
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The mention of products or services in this case study does not constitute an endorsement by EPA.

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