Page 202 - Advances In Productive, Safe, and Responsible Coal Mining

Coal mine methane: Control, utilization, and abatement 181

The amount of CMM generated at a specific mining operation depends on the pro-
ductivity of the coal mine, the gassiness of the coal seam and other underlying and/or
overlying formations, mining methods, operational variables, and geological condi-
tions. CMM can ordinarily be emitted into the mine environment and exhausted from
the mine shaft along with ventilation air. However, it may be captured by drilled bore-
holes that augment the mine’s ventilation system.
Large amounts of methane released during mining present concerns about adequate
mine ventilation to ensure worker safety, but they can also create opportunities to
generate energy if this gas is captured and utilized properly. The implementation
of cost-effective CMM utilization can yield substantial economical and environmental
advantages such as improved miners’ safety and mine productivity besides reduced
greenhouse gas (GHG) emissions.
With increasing worldwide coal production, more attention is being given to the
health, safety, and environmental impacts of methane released during coal mining.
Methane not only creates unsafe working conditions in underground mines, but also
heightens environmental concerns as it is a potent GHG. Recent research done by the
United Nations has shown that the impact of methane on the atmosphere is more far
reaching than was originally thought, and coal mines are the fourth largest source of
methane emissions after oil and gas, landfill, and livestock industries [1]. Conse-
quently, a major focus is currently being directed at minimizing methane emissions
from the entire coal industry value chain from production through utilization.
In order to minimize environmental impacts of coal mining, it is important to
ensure safe extraction, as well as control and abatement of CMM throughout the mine
life cycle. Currently, technological advances have made it possible to significantly
reduce CMM emitted even from the gassiest mines. Applying an engineering strategy
for control and useful utilization of CMM not only improves working conditions at
mines, but also provides an affordable and clean burning fuel.
This chapter focuses on everything that has anything to do with CMM capture and
utilization including methane chemistry, CMM-related disasters in coal mining, the
main factors affecting CMM accumulations in underground coal mines, methods
for capturing CMM using boreholes into and from coal mines, removing methane
from abandoned mines, benefits of capturing and controlling CMM, and the role of
CMM in energy production and environmental concerns. Recent advances are sum-
marized in an effort to help to the industry eliminate disasters and fatalities in coal
mining and also minimize the environmental impact of CMM emissions, which leads
to productive, safe, and responsible coal mining. It is hoped that those practical prin-
ciples discussed will be useful in reducing global methane emissions especially from
coal mines, and to advance the abatement, recovery, and use of CMM as a valuable
clean energy source.

10.2 Coal mine methane

The main component of the primary coal seam gas is methane in concentrations
of 80%–90%, which develops during the coalification or carbonization process.