Coal-bed methane (CBM) drainage – Environment-friendly & safer system for coal mines operation:
Over the past few decades, emissions of methane from coal mines have increased significantly because of higher productivity, greater comminuting of the coal product, and the trend towards recovery from deeper coal seams. Under current coal mine regulations of many countries, methane must be controlled at the working faces and at other points in the mine layout. This has traditionally been performed using a well-designed ventilation system. However, this task is becoming more difficult to achieve economically in modern coal mines. In addition, scientists have established that methane released to the atmosphere is a major greenhouse gas, in contributing to potential global warming. In order to improve mine safety and decrease downtime as a result of methane in the mine openings, many mines are now using a degasification system to extract much of the coal-bed methane from their seams before or during mining. Geologists are aware of the depositional environments that can produce coal-bed methane, reducing the cost of extensive exploration.
Methane drainage offers the added advantages of reducing the ventilation costs, reducing the development costs of the mine, reducing the global warming threat, and allowing a waste product to be productively utilized. Coal-bed methane is produced domestically, reducing our need to import energy. And most importantly, methane is a relatively clean-burning source of energy, much cleaner than coal. All of these factors combine to make coal-bed methane a locally-produced, affordable source of energy.
This byproduct can be gathered to produce three levels of benefits to a mining company, depending on the market potential of the methane. The benefit levels are as follows:
(1) The methane is gathered from the coal seam to reduce ventilation costs, downtime costs, production costs, and shaft development costs or to benefit from increased coal resources. All of these benefits are achieved internal to the mining operation and can be easily analyzed by the mining company.
(2) The coal-bed methane is extracted from the seams to be mined and is utilized as a local energy resource to heat buildings, dry coal output from the coal preparation facility, generate electrical power, power vehicles by compressing the gas, or other local uses.
(3) The extracted methane can be upgraded, if necessary, or immediately compressed and introduced into a commercial gas pipeline system. This may provide the highest possible benefit to the mining company providing that the methane is of high quality and the mine location is near a gas pipeline. With this option, the value of the methane as an energy resource may be very large and it can make a significant contribution to profits.
Many have their opinion that, coal-bed methane production results in changes to the land, to surface water, and to ground-water systems. These changes should be monitored and managed in order to reduce their impact. Although they are being challenged, they remain a starting point. With care, it seems that the environmental costs of coal-bed methane can be reduced.
Thus, in general, extraction of coal-bed methane provide lot of economical benefits in running coal mines, apart from providing cleaner environment by preventing release of major greenhouse gas, methane, in the atmosphere and recovering extra energy source as well.