San Francisco-based California Energy Co. plans to build a geothermal power plant at Roosevelt Hot Springs in southeastern Utah.

The project could employ up to 300 during construction and 100 when operating, officials said.The 20-to 25-megawatt plant will be located some 100 miles east of Salt Lake City.

California Energy's president David L. Sokol said Monday the plant will represent an investment of between $300 million and $500 million. He said that, while no buyer has been lined up for the power, development work should begin this summer.

The project is made possible by California Energy's completed purchase last week of Chevron's geothermal leases at six sites in Utah and Nevada for $51 million.

These leases include the rights to the geothermal springs at Roosevelt Hot Springs. California Energy also purchased about 20,000 surface acres in the vicinity.

California Energy spokesman David Cox said Utah Power & Light Co. already operates a 20-megawatt geothermal power plant at Roosevelt Hot Springs. The UP&L plant will continue operation, he said.

California energy, however, now owns about 70 percent of the steam that propels UP&L's turbines.

The steam is created by molten rock lying beneath an underground reservoir.