- Docket Number
- 110 MW
- Sonoma County
- Steam Turbine
- Project Status
- Operational (Geothermal)
- Project Type
- Application for Certification
The Socrates Geothermal project (Unit 18) is in Sonoma County near the Sonoma/Lake County line, in the Geysers Known Geothermal Resource Area along the ridgeline of the Mayacamas Mountains with moderately steep terrain, approximately 15 miles west of the town of Cobb. Unit 18, originally known as Pacific Gas & Electric Company’s (PG&E) Geysers Unit 18 Geothermal Project was certified by the California Energy Commission (CEC) in May 1980 and began commercial operation in November 1982.
Unit 18 is a dry-steam geothermal plant and was designed to provide up to 110 MW; however, due to reduced steam pressures, the plant currently supplies approximately 50 megawatts of base-load electricity to northern California's power grid. The major structures of the proposed facility are a turbine building, cooling tower, electrical switchyard, and a hydrogen sulfide abatement facility. The turbine building would house the steam turbine generator and other associated equipment required for electrical power production. The mechanical draft cooling tower would dissipate to abate hydrogen sulfide (H2S) emissions using a Stretford System which scrubs heat from the H2S from the vent gas stream from the condenser and catalytically oxidizes the gas to eliminate Sulfur.
In April 1999, the CEC granted a transfer of ownership of Socrates Geothermal (Unit 18), the former PG&E Geysers Unit 18 Geothermal Project to Geysers Power Company, LLC, a wholly owned subsidiary of the Calpine Corporation.
Power Plant Certification and Exemption Processes
As required by the Warren-Alquist Act, the Energy Commission monitors Commission-certified energy projects throughout construction, operation, and closure to ensure compliance with the conditions of certification imposed by the Commission’s Final Decision for approving the projects.