The economics of different nuclear systems to meet the low-temperature heat demand are compared. The comparison concentrates on substitute or synthetic natural gas (SNG) produced from coal and nuclear high-temperature heat. The market potential as well as the economic benefit for the Federal Republic of Germany (FRG) has been assessed under realistic boundary conditions. In spite of the relatively high investment costs, it is expected that SNG can be competitively used in the FRG. If a price escalation rate of natural gas slightly above the general inflation rate is assumed, a large public benefit can be expected.