coal gas: A fuel gas produced by thedestructive distillation of coal. In thelate-19th and early-20th centuriescoal gas was a major source of energyand was made by heating coal in theabsence of air in local gas works. Typically,it contained hydrogen (50%),methane (35%), and carbon monoxide(8%). By-products of the process werecoal tar and coke. The use of thistype of gas declined with the increasingavailability of natural gas, althoughsince the early 1970s interesthas developed in using coal in makingSNG.
