Quality of CMM
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Definition and Origin
"Coalbed Methane (CBM) is methane contained in coal seams, and is often referred to as virgin coalbed methane, or coal seam gas" (EPA Climate Change Glossary of climate change terms). It refers to the methane gas found in coal deposits.
Coal Mine Methane (CMM) is the subset of CBM that is released from the coal seams during the process of coal mining. The CMM described and discussed in this Wiki is an anthropogenic emission.
CMM resources
| CMM Ressource | extracting possibility | time of extracting | CH4 - content |
|---|---|---|---|
| Active Mine | Underground CMM extracting system | during mining | 25 % - 65 % |
| Surface borehole | during and after mining | 25 % - 95% | |
| Surface ventilation borehole | during mining | < 4% | |
| Abandoned Mine | Degassing pipes and abandoned shafts | post mining | 25 % - 85 % |
| New boreholes into old gallery | post mining | 25 % - 85 % | |
| Pre Mining (CBM) | boreholes into unworked coal layers | pre mining | > 90 % |
A Glossary of terms prepared by a workgroup of "Methane to Markets" provides numerous of explanations to the special wording in CMM utilisation. 
