Geothermal energy and the environment: The global experience

The conflict between energy supply and the environment is one of the critical issues of our time, and geothermal energy, often touted as plentiful and environmentally benign, has received a measure of attention as one possible answer to the problem. Some environmental issues, however, have been encountered during the development of the world's geothermal resources and these have had an impact on the speed of development. The environmental problems at each of the world's geothermal generating stations are discussed in this paper. The significant environmental impacts include conflicts in land use, air pollution, subsidence, water pollution, induced seismicity, blowouts, and noise, and every country has encountered some difficulty with one or more of these problems. Development plans have been slowed by environmental concerns in some countries. In the U.S.A., this problem has been the emission of hydrogen sulfide; in Japan, land use in national parks plus waste-water disposal; in El Salvador, waste-water disposal. Other environmental impacts which have not had an appreciable effect on development plans include: waste-water disposal and subsidence in New Zealand, land use and air pollution in Mexico. Italy has encountered no particular environmental barriers yet, but this may be a function of minimal monitoring. Collectively, the environmental difficulties at the operating power stations around the world have been minor compared to the actual disasters that have befallen other processes of generating electricity. Even the potential environmental hazard of geothermal energy development is much less. It cannot be compared to a massive oil spill, a strip mine, or a radiation leak. Nevertheless, geothermal development faces an array of rules and regulations which, in view of world-wide environmental experience, need not be so strict. Regulation is particularly tight in the United States, a country which would, with appropriately relaxed controls, stimulate a global acceleration in development. Instead, the U.S. lies smothered in rules, and electrical geothermal development everywhere remains mired in a role of insignificant contribution.