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Coal mine methane: Control, utilization, and abatement 193

can be economically applied for CMM projects are under construction. As an inter-
esting example, there is one vehicle fuel project at the Furong Mine in Sichuan, China,
which uses CMM to fuel buses.
CMM can be used in boilers for space and water heating. For example, CMM has
the potential to be used onsite or nearby a gassy mine for residences that require hot
water. Furthermore, it is desirable to heat ventilation air in the winter before pumping
into the mine. Conversely, heat exchangers may be used to cool the air in deep, high-
temperatures mines.
CMM may also be used as a chemical feedstock, such as in methanol or carbon
black production. Other practical applications are coking coal development, fuel
for aluminum hydroxide roasting furnace systems and glassworks factories, a fuel
source for fuel cells, and a feedstock for producing dimethyl ether (C 2 H 6 O) [17].
In addition, CMM is sometimes used in coal preparation plants to fuel thermal dryers
that heat the air used to remove surface moisture from coal.
Hence, capturing CMM not only mitigates concerns for climate change, but also
delivers other important cobenefits, including improvement of mine safety and pro-
ductivity, localized energy production, and improvement in local air quality. More-
over, CMM has the potential to provide a cleaner burning fuel for use at the mine
or for sale.
Specific CMM end uses depend on the gas quality, especially the concentration of
methane and the presence of other contaminants. One problem with CMM is great
variability in its composition; VAM may contain 0.1%–1% methane, whereas
CMM drained from the unmined seams prior to mining may contain 60% to more than
95% methane. CMM drained from fractured formations above gob area may also con-
tain 30%–95% methane depending on borehole locations and other operational and
completion parameters [18]. Since pipeline grade natural gas must be at least 96%
pure methane, lower-quality mine gas must be upgraded for distribution by removing
water and inert gases.
Technology is now readily available to recover high-quality CMM that can be used
as fuel while simultaneously reducing mining hazards. In 2008, over 200 CMM
projects developed in 14 countries capturing more than 3.5 billion cubic meters
(124 billion cubic feet) per year [19,20]. Hence, CMM recovery is a clean technology
that can reduce mining costs and make operations much safer and more economical by
turning a safety hazard into a valuable energy resource.

10.5 CMM abatement

As a whole, methane emissions related to coal mining can be categorized into five
groups based on emission sources: (i) vented VAM, (ii) AMM that is seeping out,
(iii) surface mine emissions, (iv) emissions from degasification systems, and
(v) fugitive emissions from postmining operations. The greatest amounts of post-
mining methane emissions occur when coal is crushed and sized, which results in
increased surface area allowing the methane to rapidly desorb and be emitted to
the atmosphere especially during transportation.