917.    ---------------.   [FIELDNER, A. C.]  Nation’s Reserve of Solid Fuels and Its Relation to the Future Supply of Gaseous and Liquid Fuels.  Rept. to Federal Power Commission, June 1946, 12 pp.; Gas, vol. 22, 1946, pp. 70, 75, 78; Gas Age, vol. 98, No. 6, 1946, pp. 37-40, 42; Coal-Heat, vol. 50, November 1946, pp. 30-34; Mech. Eng., vol. 69, 1947, pp. 221-226, 228.

     Reserves of mineral fuels in the United States are estimated as follows:  Coal, 3.2 trillion tons; petroleum, 20.8 billion bbl.; natural gas, 135 trillion cu. ft.  In terms of equivalent heating value, (coal taken at 13,000 B.t.u.), coal comprises 98.8% of the mineral-fuel energy reserves, oil shale 0.8%, petroleum 0.2%, and natural gas 0.2%.  The coal reserves are distributed among the different ranks of coal on the basis of energy content in the following proportions:  Anthracite, 0.6%; low-volatile bituminous coal, 2.2%; high-volatile bituminous coal, 54.2%; subbituminous coal, 23.1%; lignite, 18.7%.  The ultimate reserves of oil and gas are, therefore, very small as compared to the reserves of coal and lignite, and as the supply of oil and natural gas declines, it will be necessary to resort to coal either by direct substitution or by conversion of it to liquid and gaseous form.  Fuel gases from coal by carbonization or complete gasification have been in commercial use for a long time, and recently processes have been developed for the conversion of coal to liquid fuel by the direct hydrogenation of coal or hydrogenation of tars or gases produced from coal.  For coal hydrogenation by the Bergius process, most of the high-volatile bituminous coals, the subbituminous coals, and the lignites are suitable, while for the Fischer-Tropsch process, almost any carbonaceous material that can be reacted with steam to produce CO and H₂ is a potential source of liquid fuel.  Furthermore it is not believed that the cost of producing liquid fuels by either of these processes will be in any sense prohibitive.  From reports of German developments and from British and American estimates, it appears that, in general, gasoline can be produced by the hydrogenation of solid fuels for about $0.10-$0.15 per gal. more than from petroleum, and by the Fischer-Tropsch process for $0.06-$0.08 per gal. more.