Coal Mine Gas

Coal gas is present in fissures, faults and pores of coal seams and as adsorbed gas on the inner surface of coal and neighboring rock. It’s developed during the geochemical conversion of organic substances to coal. Coal mine gas is a problematic phenomenon associated with pit coal mining since the gas and air can form explosive mixtures. It is an explosive gas that needs to have ventilation or capture system when during and after mining. Dependent on the capturing time and method, three different types of coal mine gas can be identified:

  1. Coal Bed Methane (CBM)

    Coal Bed Methane or Coal Seam Gas (CSG) is from un-mined coal beds consists of more than 90% methane and can be harvested independently of coal mining. The gas composition is very stable which is able to be fed either directly into the natural gas network or a gas engine.

  2. Coal Mine Methane (CMM)

    Coal Mine Methane, a methane/air mixture released during active coal mining which must be vented and captured for safety reasons. CMM typically has an oxygen content from 5% to 15%. The methane content ranges from 25% to 60%. Since the gas proportion is not steady, thus complicating its use in gas engines.

  3. Abandoned Mine Methane (AMM)

    Coal mine gas continues to be released even after coal mines are shut down. Coal mine gas from abandoned mines typically contains no oxygen, but a considerable amount of carbon dioxide (3-20%), and its composition changes slowly compared to CMM. The methane content ranges from 40% to 80%.

Considering the safety, power demands at site for mining and to avoid the GHG (Green House Gas) releasing problems. Gas engine driven energy module may become to an efficient solution for issues listed above.

advantages

  • Electrical efficiency of more than 40%, and up to more than 80% efficiency in the case of combined heat and power
  • Alternative disposal of a problem gas while simultaneously harnessing it as an energy source
  • Increased worker safety due to installation or refurnishing of gas suction system
  • Additional revenues from feed-in tariffs or through carbon credit projects