煤气
Gasification of coal or lignite or pet coke produces syngas or coal gas or coke oven gas which is a mixture of hydrogen, carbon monoxide and carbon dioxide gases. Coal gas can be converted into synthetic natural gas (SNG) by using Fischer–Tropsch process at low pressure and high temperature. Coal gas can also be produced by underground coal gasification where the coal deposits are located deep in the ground or uneconomical to mine the coal. CNG and LNG are emerging as economical alternatives to diesel oil with the escalation in international crude oil prices. Synthetic natural gas production technologies have tremendous scope to meet the transport sector requirements fully using the locally available coal in India. Dankuni coal complex is producing syngas which is piped to the industrial users in Calcutta. Many coal based fertiliser plants which are shut down can also be retrofitted economically to produce SNG as LNG and CNG fetch good price by substituting imports. Recently, Indian government fixed the natural gas price at producer end as US on net calorific value (NCV) basis, which is at par with the estimated SNG price from coal.