Geothermal Energy: Status in 1987

Richard F. Dondanville

The geothermal industry produces natural earth heat for use directly or through electrical generation. Although energy recovery from hot, dry rock has been studied, all commercial geothermal systems produce from porous, permeable, water-bearing reservoirs.

Most existing hydrothermal reservoirs hot enough to produce electricity have a shallow magmatic heat source. The restricted distribution of cooling magma chambers has limited the geographic availability of geothermal electricity.

Worldwide geothermal electrical generating capacity was 293 megawatts (MW) in 1958, 675 MW in 1970, 1,362 MW in 1976, and 2,828 MW in 1981. By 1987, worldwide capacity is 4,553 MW divided among 18 countries. That capacity, operating continuously, would consume 66 million bbl of oil per year. The six leading countries (United States, 2,048 MW; Philippines, 887 MW; Italy, 500 MW; Mexico, 425 MW; Japan, 228 MW; and New Zealand, 167 MW) have a combined capacity of 4,255 MW.

By 1990, total capacity will approximate 6,100 MW divided among 27 countries. Biggest increases will be in the United States (515 MW), Indonesia (220 MW), and New Zealand (136 MW).

Direct heat use ranges from casual bathing in hot springs to organized space heating systems where prolific, moderate-temperature reservoirs exist.

An estimate of direct heat use capacity in the 18 countries which exceed 10 megawatts thermal (MWt) is 7,049 MWt. That capacity, operating 60% of the time, represents an equivalent of 21 million bbl of oil per year. The six leading countries (Japan, 2,686 MWt; Hungary, 1,001 MWt; Iceland, 889 MWt; USSR, 402 MWt; China, 393 MWt; and United States, 339 MWt) have a combined capacity of 5,710 MWt.

AAPG Search and Discovery Article #91038©1987 AAPG Annual Convention, Los Angeles, California, June 7-10, 1987.