United States
Environmental Protection Agency
Air and Radiation
October 1997
      EPA Coalbed Methane Outreach Program Technical Options Series
                   Colorado Greenhouse Facility Near Rifle, Colorado
     (Uses Waste Heat From Adjacent Natural Gas Fueled Cogeneration Plant To Grow Tomatoes)
    * 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
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
 Greenhouses may be
  able to use some of
   the mine's waste
  water for irrigation
Benefits for  Greenhouses, Coal Mine Operators,  and  the

  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

  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

  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
                                                             '  R  O  0  R A M
 The mention of products or services in this case study does not constitute an endorsement by EPA.