Publications

Underground coal gasification (UCG) is a process in which coal is converted in situ to a combustible gas that can be used as a fuel, chemical feedstock and syngas. UCG is a process used to produce gas, primarily hydrogen, carbon monoxide, carbon dioxide, and methane by partially combusting underground coal in the presence of water and a controlled oxygen supply (Walker, 1999). According to Geological Survey Ministry of Energy and Mineral Resources (ESDM), Indonesia’s total coal recources are estimated at 65.4 billion tons and reserves of 2.6 to 12 billion tons. Presently, Indonesia is most likely to burn coal for conversion to electricity. Because the burning of coal produces pollutan gases such as CO2, SO2, NOx and CxHy, this use is inefficient. However, nearly 85% of known coal reserves are deemed uneconomic for surface mining because they are too remote, too deep, or below caloric threshold. It is in these regions that UCG has much to offer. The process of coal gasification in a surface, gasifier can be replicated underground by drilling into the coal seam, injecting air or oxygen, and gasifying the coal seam in situ. The produced gas is transported to the surface (Walker, 1999). UCG technology can recover up to 80% of the calorific value of coal, a significant increase over other coal extraction methods. When combined with CO2 storage in the depleted coal seams, UCG creates a source of energy that rivals nuclear reaction for low emissions and has lower unit costs than conventional gas-fired power stations. Keywords : underground coal gasification, syngas, UCG processes, coal seam.