Development of the giant steam field at The Geysers, California, largely by private industry, has continued steadily, with over 900 Mw of generation online, and nearly 500 Mw additional under construction or design. The area of the field is at least 15 mi² (40 km²); production depth is from 0.8 to about 1.9 mi (1.3 to about 3 km). Immediately adjacent to the east, exploration of hot water resources (to 482°F, 250°C) is underway. In Imperial Valley, California, several small plants (10 to 50 Mw) are either operating or under development. These are located in a sedimentary basin, essentially nonvolcanic, but having an extremely thin crust. Brine salinities remain a major problem.

Geothermal power plants are under construction or design in Utah and Nevada. On Hawaii island, a pilot 3 Mw plant is operational. Total US geothermal generation is now about 1,000 Mw.

Research into power generation from low-temperature fluids (302°F, 150°C) has resulted in construction of a 5 Mw binary-cycle experimental station at Raft River, Idaho, using federal funds. Federal funds also are used in research into energy extraction from hot dry rocks and from high-pressure methane-bearing sands at great depths along the Gulf Coast.

Low-temperature utilization to date has been limited mostly to demonstration projects using public funds in Idaho, South Dakota, Texas, Oregon, etc, heating buildings with waters of 122 to 212°F (50 to 100°C). This segment of the geothermal industry continues to need public support in order to become competitive.

Perhaps the most significant change has been the growth of interest and activity by electric utilities, especially publicly owned utilities in California. Several now are investing in exploration, singly or in joint ventures with traditional exploration companies. Tax-exempt status, lower burrowing costs, and lack of profit demands add to their competitiveness.

Current exploration interest is focused on the volcanic Cascade Range, Imperial Valley, areas in northern Nevada, the Coso Range of California, and the greater Geysers-Clear Lake region.

End_of_Article - Last_Page 973------------