430F98085
&EPA
United States
Environmental Protection Agency
Air and Radiation
6202J
Draft
October 1997
EPA Coalbed Methane Outreach Program Technical Options Series
USE OF COAL MINE METHANE IN GREENHOUSES
Colorado Greenhouse Facility Near Rifle, Colorado
(Uses Waste Heat From Adjacent Natural Gas Fueled Cogeneration Plant To Grow Tomatoes)
PROFITABLE OPPORTUNITIES FOR GREENHOUSE AND MINE OPERATORS
GREENHOUSES CAN...
* Use methane from coal mine pre-drainage and gob wells as a heating fuel
* Use electricity generated on-site or nearby from coal mine methane
* Use CO2-enriched coal mine ventilation air to maintain consistent temperatures and
stimulate plant growth
* Use coal mine waste water for irrigation at some locations
-------
Depending on
negotiations, coal
mine methane can be
cheaper than
conventional natural
gas for heating
Why Consider Using Coal Mine Methane in Greenhouses?
The cost of electricity
from a coal mine
generating power on
site could be as low
as $0.04 per kWh,
which is typically less
than commercial
power rates
M
I any coal mines in the United States and other countries emit high
volumes of methane. In the U.S., these volumes may range from less
than 0.5 million cubic feet per day (mmcf/d) to more than 10 mmcf/ti.
Greenhouses can use coal mine methane to meet their fuel requirements. At
least one greenhouse in the Midwest is using coal mine methane to produce
heat and electricity. Several gassy mines in the United 'States are capable of
meeting the heating and electricity requirements that most greenhouses have. A
greenhouse could purchase methane directly from the mine for use as a heating
fuel, A mine can usually sell methane at a negotiated price that is lower than
what the greenhouse would pay for conventional natural gas or other fuels.
Based on these points, greenhouses can reduce their operating costs, while the
mine benefits from sale of the methane. A greenhouse could also purchase
electricity from a coal mine that has existing electric generating capability.
While the primary driving forces for locating greenhouse operations near gassy
coal mines are the potential net energy savings for the use of methane for
heating and/or electricity production, there may be secondary financial benefits
as well. One secondary benefit is the potential for use of mine ventilation air in a
greenhouse to help stimulate plant growth. Ventilation air is rich in CO2 (2,000-
3,000 ppm in ventilation air as compared to 300-400 ppm in the atmosphere).
Ventilation air also remains at a fairly constant temperature year-round, which
can help maintain consistent greenhouse temperatures. Another potential benefit
is the use of mine wastewater for irrigation purposes in cases where the quality of
this water is suitable for greenhouse needs.
Some greenhouses
have been able to
reduce heating costs
by 87% using mine
ventilation air to
modify greenhouse
temperatures
Greenhouses may be
able to use some of
the mine's waste
water for irrigation
Benefits for Greenhouses, Coal Mine Operators, and the
Environment...
• New' Markets. Coal mines need a market for their methane, and
greenhouses have a large energy demand.
• Lower Prices. In many cases, gassy coal mines can supply methane to a
greenhouse at a lower cost than commercial retail gas or electricity prices.
• Increased Revenue. Coal mine operators gain additional, stable revenue
sources.
• Reduced Costs. The greenhouse operator would benefit from reduced
energy costs, water, and CO2.
• Environmental. Use of coal mine methane protects the global environment
by reducing emissions of methane, a greenhouse gas, to the atmosphere.
-------
Key Factors Affecting Coal Mine/Greenhouse Project Economics.
• For a project to be economic, the mine must generally be able to recover at least 0.3 mmcf/d of
methane
• Greenhouses with electricity needs of at least 5 million kWh/year and heating needs of at least 100
billion BTUs/year will be good candidates
• Projects with smaller greenhouses can be profitable given certain site-specific and market
conditions (e.g., high electricity rates, cold climate, and high water costs)
• Locating the greenhouses close to the mine can minimize fuel transport costs
Additional information on this topic can be found in the EPA report, Making Coal Mine Methane Work
for You: A Guide to Coal Mine/Greenhouse Projects, February 1998.
For More Information.
Greenhouse operators are seeking ways to improve economics by reducing fuel costs.
Meanwhile, increasing numbers of coal mine operators are initiating methane recovery projects in
an effort to increase mine safety and productivity, as well as gain additional revenues from
methane sales. The use of coal mine methane in greenhouses can provide financial benefits to
both parties.
EPA is analyzing the economic and financial benefits of coal mine methane use in greenhouses.
For more information about this and other profitable uses for coal mine methane, contact:
Coalbed Methane Outreach Program
U.S. EPA (6202J)
401 M Street, SW
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
METHANE
OUTREACH
' R O 0 R A M
The mention of products or services in this case study does not constitute an endorsement by EPA.
------- |