- About CMOP
- Methane Emissions from Coal Mines
- Ventilation Air Methane (VAM)
- Abandoned Mine Methane
- International Emissions of CMM
- Recovery and Use of Coal Mine Methane
- Benefits of Capturing and Using Coal Mine Methane
EPA's Coalbed Methane Outreach Program (CMOP) is a voluntary program with a goal of reducing methane emissions from coal mining activities.
CMOP's mission is to promote the profitable recovery and utilization of coal mine methane (CMM). Coal mine methane is a potent greenhouse gas that contributes to climate change if emitted to the atmosphere. CMM can also create an explosive hazard inside mines. But if CMM is recovered safely and used for energy, it is a valuable, clean-burning fuel source.
Since 1994, CMOP has worked cooperatively with the coal mining industry in the U.S. and internationally to reduce CMM emissions. By helping to identify and implement methods to recover and use CMM instead of emitting it to the atmosphere, CMOP has played a key role in the United States' efforts to reduce greenhouse gas emissions and address global climate change.
Our program goals:
- Reduce greenhouse gas emissions
- Achieve the profitable recovery and use of CMM
- Promote use of a clean energy source
Methane Emissions from Coal Mines
CMM refers to methane released from the coal and surrounding rock strata due to mining activities. In underground mines, it can create an explosive hazard to coal miners, so it is removed through ventilation systems. In some instances, it is necessary to supplement the ventilation with a degasification system consisting of a network of boreholes and gas pipelines. In abandoned mines and surface mines, methane might also escape to the atmosphere through natural fissures or other diffuse sources.
Sources of CMM
Source: U.S. Emissions Inventory, 1990 - 2012
Coal mine methane is emitted from five sources:
- Degasification systems at underground coal mines (also commonly referred to as drainage systems). These systems may employ vertical and/or horizontal wells to recover methane in advance of mining (known as "pre-mine drainage") or after mining (called "gob" or "goaf" wells)
- Ventilation air from underground mines, which contains dilute concentrations of methane
- Abandoned or closed mines, from which methane may seep out through vent holes or through fissures or cracks in the ground
- Surface mines, from which methane in the coal seams is directly exposed to the atmosphere
- Fugitive emissions from post-mining operations, in which coal continues to emit methane as it is stored in piles and transported
The EPA annually publishes estimates of these emissions along with an explanation of the methodologies used in the U.S. Emissions Inventory, 1990 - 2012.
Ventilation Air Methane
Methane is an explosive gas that is a hazard to underground miners. To ensure mine safety, fresh air is circulated through underground coal mines using ventilation systems to dilute in-mine concentrations of methane to levels well below explosive levels. Mine safety authorities in each country regulate these concentrations. Typically, methane concentrations in ventilation air range from 0.1 percent to 1.0 percent.
Ventilation air methane (also known as VAM) refers to the very dilute methane that is released from underground mine ventilation shafts. VAM represents over half of all coal mining emissions in the United States and worldwide. With few exceptions, it is simply released to the atmosphere.
It is technically possible to convert the dilute methane in ventilation air to useful energy. The economic feasibility of these projects on a commercial scale is being demonstrated. For more information, see
- Coal Mine Ventilation Air Emissions: Project Development Planning and Mitigation Technologies (PDF, Aug. 2010) (8 pp, 556K, About PDF)
- New Publications of interest: VAM technology demonstration projects
Abandoned Mine Methane
When coal mines are no longer operated to produce coal, they are known as closed (or "abandoned") mines. Even though active mining no longer occurs, these closed mines can still produce significant methane emissions from diffuse vents, fissures, or boreholes. This methane can be deliberately extracted and used to generate power or for other end uses.
There are several thousand abandoned coal mines in the U.S. Of these, EPA has identified some 400 abandoned mines that are considered "gassy" and has developed profiles of successful projects at abandoned mines and mines that may be good candidates for project development.
The EPA developed a methodology to estimate fugitive methane emissions from abandoned mines. This methodology is incorporated in the 2006 IPCC Guidelines for National Greenhouse Gas (PDF) (78 pp, 674K, About PDF)
- Abandoned mine methane emissions inventory methodology, including abandoned coal mine database (PDF) (90 pp, 2.0MB, About PDF)
International CMM Emissions
Coal mine methane emissions are globally distributed among the world's key coal-producing countries. Methane is a well-mixed gas in the atmosphere and emissions reductions anywhere in the world are important to reducing the total global burden of CMM emissions.
Source: Global Anthropogenic Non-CO2 Greenhouse Gas Emissions, 1990 - 2030
For many years, CMOP has been actively engaged in helping to promote recovery and utilization of coal mine methane in many key coal-producing countries, including China, India, Kazakhstan, Mongolia, Poland, the Russian Federation, and Ukraine.
Benefits of Capturing and Using Coal Mine Methane
There are numerous benefits to capturing and using coal mine methane, including:
- Reducing greenhouse gas emissions
- Conserving a local source of valuable, clean-burning energy
- Enhancing mine safety by reducing in-mine concentrations of methane
- Providing revenue to the mine
Recovery and Use of Coal Mine Methane
Technology is readily available to recover methane (CH4) – the major component of natural gas – from coal mines. Specific CMM end-uses depend on the gas quality, especially the concentration of methane and the presence of other contaminants.
Worldwide, CMM is most often used for power generation, district heating, boiler fuel, or town gas, or it is sold to natural gas pipeline systems.
CMM can also be used in many other ways:
- Coal drying
- Heat source for mine ventilation air
- Supplemental fuel for mine boilers
- Vehicle fuel as compressed or liquefied natural gas (LNG)
- Manufacturing feedstock
- Fuel source for fuel cells
According to the U.S. Emissions Inventory, 1990 - 2012, nearly all CMM captured and used from active U.S. mines is injected into the natural gas pipeline system.
As outlined in EPA's report on the Global Mitigation of Non-CO2 Greenhouse Gases (PDF) (410 pp, 5.87MB, About PDF), the global potential for economically viable methane recovery and use projects is significant, even in the absence of a price signal for methane emissions. As the breakeven price for methane reductions rises, the mitigation potential grows.