Natural-gas supplements are required today to meet peak-load demands near centers of consumption. They will be required on a much larger scale at some time in the future when the demand for gas exceeds the deliverability of domestic supplies.

Supplements for peak-load use include liquefied petroleum gases (LPG), particularly propane; liquefied natural gas; and high-Btu oil gas produced in cracking processes. The combustion characteristics of the supplemental gas determine the maximum concentration in the mixture distributed.

When it becomes necessary to supplement domestic supplies of natural gas to meet the demand, there will be two alternatives, (1) importation of liquefied natural gas, which is technically feasible today, and (2) production of synthetic high-Btu gas (primarily methane) from vast domestic reserves of coal and oil shale.

Two high-Btu-gas production processes are under development. In one, synthesis gas, principally carbon monoxide and hydrogen, produced by gasifying coal with oxygen and steam, is converted catalytically to methane (methanation process). In the other, coal or oil shale reacts directly with hydrogen to produce methane (hydrogasification process).