USE OF MINE VENTILATION EXHAUST AS COMBUSTION AIR IN GAS-FIRED TURBO-ELECTRIC GENERATORS

Methane liberated in coal mines is a potential safety hazard, because it is explosive at relatively low concentrations (5%-15%) in air. To m anage methane, underground mines are ventilated with large quantities of air and, in some cases, the gas is also drained with gob wells and predrained with vertical and horizontal wells, The ventilation air is used to dilute methane emissions to levels veil below the explosive li mit, and the diluted stream is discharged to the atmosphere, Unfortuna tely, this waste stream may contain as much as 60% of the total gas en ergy that was originally in the coal, Also, methane is considered by s ome to be 24.5 times more detrimental than CO2 in contributing to the greenhouse effect, The volume of the waste stream, the high electric p ower demands of a mine, and the greenhouse effect of methane provide a strong incentive for converting the waste-methane chemical energy to the electrical or mechanical equivalent, A preliminary economic assess ment of a proposed test-turbine installation at the Jim Walter Resourc es Blue Creek Mine Number 5 (JWR No. 5) shows that such a project make s good sense economically, even without considering the emission-reduc tion benefits, This unit could produce enough power to drive a ventila tion fan, provide a profitable rate of return, and produce a 2% reduct ion in emissions, A market study indicates that there is the potential to generate 706-816 MW of power from mine ventilation gas in the U.S. Worldwide, if only 10% of the estimated mine ventilation emissions ca n be used for power generation, this technology has potential for the generation of 1689-1953 MW of capacity, with a commensurate reduction in emissions.