FAQs
How does geothermal heat produce electricity?
Once geothermal waters reach the surface, the steam is sent to the power plant and used to drive generators to produce electricity, and the brine and gases are re-injected back into the injection zone below the water table. Combined, Puna Geothermal Venture’s five production wells normally produce an average of two million pounds of geothermal fluid per hour. Like wells in other volcanic regions (Indonesia, Philippines and Iceland), PGV’s wells are considered prolific in comparison to other types of geothermal wells in the industry.
There are three types of power-generating plants: dry steam, flash steam and binary cycle. Dry steam plants, first used in Italy more than 100 years ago, route the steam directly to a power plant to produce electricity. Dry steam plants are used in places such as The Geysers in California, where steam is close to the surface. Flash steam power plants cause the fluid to rapidly vaporize, driving turbines that in turn drive a generator. Binary-cycle plants are similar and the most advanced. Their closed-loop circulation system means that no excess gases or fluids reach the open air. PGV’s power plant utilizes the closed-loop binary system.
Where is geothermal energy found in the U.S. and worldwide?
Most geothermal reserves are found in the western states, Alaska and Hawaii. States such as California boast reserves of shallow steam. Nevada, Oregon, Idaho, Arizona and Utah are all areas of rapid geothermal growth.
The Hawaiian Islands lie above a geothermal “hot spot” that has been volcanically active for millions of years. Based on geothermal exploration conducted in the 1970s, the slopes of Kilauea Volcano on Hawaii Island have the most potential for generating electricity and direct utilization. Maui has been listed as a possible site, too.
Worldwide, geothermal power is being generated in more than 20 countries including Canada, Icelend, Italy, France, New Zealand, Mexico, Nicaragua, Costa Rica, Russia, The Phillipines, Indonesia, China, Japan, the rift valley of Africa and the U.S.
Early geothermal exploration in Hawaii.
The Hawaii Geothermal Assessment Program of 1978 initiated studies of potential geothermal sources statewide. The most viable locations were on Hawaii Island, primarily in the Kilauea East Rift Zone. A public-private partnership dug the first geothermal well in Puna in 1976, tapping volcanic steam for energy. The project developed into a two-year experimental 3-megawatt power plant that went online in July 1981. The plant’s output was sorely needed at the time, due to islandwide energy shortages, so it continued for eight years. Since the project was never intended as a commercial operation, the plant was not built with the best available control technology. Inadequate maintenance took its toll on the plant, costs began to exceed revenues produced, and disposal systems for excess gases and brine did not meet community or regulatory standards. Production ceased in 1989.