Coalbed Methane Outreach Program

Coal Mine Methane Sources

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Coal mine methane (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.

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

Active Underground Mines

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Active Surface Mines

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Ventilation Air Methane (VAM)

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Abandoned Underground Mines

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