Geysers Unit 5-20
Geysers Unit 5-20 is a geothermal plant in Sonoma County, California, operated by Geysers Power Co LLC. Among the 66 geothermal plants in the country it is the largest. Counting by its oldest working unit (1971), it is the oldest of the 66 geothermal plants still running in the United States. It is the biggest of California’s 32 geothermal plants. Its oldest working unit dates from 1971, earlier than at any other geothermal plant in California.
Nameplate capacity, 2025
1,236 MW
644 MW net summer capacity
12 operable units
- Geothermal1,236 MW100%
Unit by unit, 1971 to 2025
operating in 2025retiredbar height follows unit size
Unit U5 Geothermal, 59.4 MW, 1971
Unit U6 Geothermal, 59.4 MW, 1971
Unit U7 Geothermal, 59.4 MW, 1972
Unit U8 Geothermal, 59.4 MW, 1972
Unit U10 Geothermal, 55 MW, 1973–2006
Unit U9 Geothermal, 55 MW, 1973–2006
Unit U11 Geothermal, 119 MW, 1975
Unit U12 Geothermal, 119 MW, 1979
Unit U13 Geothermal, 140 MW, 1980
Unit U14 Geothermal, 124 MW, 1980
Unit U17 Geothermal, 124 MW, 1982
Unit U18 Geothermal, 124 MW, 1983
Unit U16 Geothermal, 124 MW, 1985
Unit U20 Geothermal, 124 MW, 1985
Among California’s plants
Largest plants in the state by nameplate capacity, with the plants ranked next to this one.
- 1Diablo Canyon2,323 MW
- 2Dynegy Moss Landing Power Plant Hybrid1,848 MW
- 3Haynes1,739 MW
- 4Castaic1,682 MW
- 5Ormond Beach1,612 MW
- 6Geysers Unit 5-20this plant
- 7La Paloma Generating Plant1,156 MW
- 8AES Alamitos LLC1,115 MW
Other rankings
- All US power plants
- 209th of 14,286
- Power plants in California
- 6th of 1,870
- Plants in the California ISO balancing area
- 4th of 1,637
- Plants run by Geysers Power Co LLC
- 1st of 4
- Biggest single unit, among California’s plants
- 115th of 1,870
Operable units
| Unit | Technology | Nameplate | Summer | Online | Status |
|---|---|---|---|---|---|
| U5 | Geothermal | 59.4 MW | 45 MW | 1971 | Operating |
| U6 | Geothermal | 59.4 MW | 45 MW | 1971 | Operating |
| U7 | Geothermal | 59.4 MW | 40 MW | 1972 | Operating |
| U8 | Geothermal | 59.4 MW | 40 MW | 1972 | Operating |
| U11 | Geothermal | 119 MW | 68 MW | 1975 | Operating |
| U12 | Geothermal | 119 MW | 51 MW | 1979 | Operating |
| U14 | Geothermal | 124 MW | 60 MW | 1980 | Operating |
| U13 | Geothermal | 140 MW | 65 MW | 1980 | Operating |
| U17 | Geothermal | 124 MW | 60 MW | 1982 | Operating |
| U18 | Geothermal | 124 MW | 60 MW | 1983 | Operating |
| U16 | Geothermal | 124 MW | 60 MW | 1985 | Operating |
| U20 | Geothermal | 124 MW | 50 MW | 1985 | Operating |
Retired units
Retired capacity here totals 110 MW, mostly geothermal units.
| Unit | Technology | Nameplate | In service |
|---|---|---|---|
| U10 | Geothermal | 55 MW | 1973–2006 |
| U9 | Geothermal | 55 MW | 1973–2006 |
Grid and site
- Balancing area
- California ISO
- Reliability region
- Western Electricity Coordinating Council
- Highest grid connection voltage
- 230 kV
- Water source
- Wells
- Nearest town on record
- Middletown
- Operator type
- Independent producer
- Coordinates
- 38.777°N, 122.745°W
Closest plants
| Plant | Runs on | Capacity | Distance |
|---|---|---|---|
| Calistoga Power Plant | Geothermal | 176 MW | 0.8 mi north |
| Sonoma California Geothermal | Geothermal | 78 MW | 1.1 mi northwest |
| West Ford Flat | Battery storage | 25 MW | 1.5 mi northeast |
| Geothermal 1 | Geothermal | 110 MW | 2.2 mi southeast |
| Geothermal 2 | Geothermal | 110 MW | 2.6 mi southeast |
| Bear Canyon | Battery storage | 13 MW | 3.0 mi east |
| Bottle Rock Power | Geothermal | 55 MW | 4.2 mi north |
| Aidlin Geothermal Power Plant | Geothermal | 25 MW | 8.3 mi northwest |