The authors investigated the amount of carbondioxide and methane release from coal mines in Japan. As theresults, 99.5kg-CO_2/t-Coal (4.15g-CO_2/MJ-Coal) isdischarged by the extraction of coal. More than 90 percent ofcarbon dioxide discharge by the extraction is caused by energyconsumption. Methane emission from coal mine is 11.5kg-CH_4/t-Coal (0.480g-CH_4/MJ-Coal or 16.1m~3-CH_4/t-Coal).If GWP(Global Warming Potential) is considered, the methaneemission gives larger effect to the global warming than thecarbon dioxide emission. Comparing the obtained results withforeign data considering the emission by the transportation, it isknown that domestic coal has potential to be competitive toimported coal from the point of carbon dioxide emission.
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