How many geothermal power plants are in CAISO?

CAISO has 15 operating utility-scale geothermal power plants with 2.2 GW of capacity, according to the EIA's monthly survey of power plants.

What is the largest geothermal power plant in CAISO?

Geysers Unit 5-20 in Sonoma County, California is the largest, at 1,236 MW. It came online in 1985.

How many geothermal power plants were built in CAISO in 2025?

0 geothermal power plants came online in CAISO in 2025, with 0 MW of capacity.

Who is developing geothermal power plants in CAISO?

Interconnection queues list each project under a project company, not the developer behind it. Cleanview researches the developer of every project and has them on paid plans.

Geothermal power plants in CAISO

CAISO has 15 operating geothermal power plants with 2.2 GW of capacity.

Operating15

Updated monthly. Last updated November 2026.

Under 50 MW50–249 MW250 MW and up

Updated monthly. Last updated November 2026.

CAISO had 14 geothermal power plants online in 2016 and 15 in 2026

2016’162017’172018’182019’192020’202021’212022’222023’232024’242025’252026’26

Geothermal power plants online at the end of each year. Source: EIA-860M, compiled by Cleanview.

The 10 largest geothermal power plants in CAISO

Operating, by capacity

#	Geothermal power plant	Location	Year online	Capacity
1	Geysers Unit 5-20	Sonoma County, California	1985	1,236 MW
2	Calistoga Power Plant	Lake County, California	1984	176 MW
3	Geothermal 1	Sonoma County, California	1983	110 MW
4	Geothermal 2	Sonoma County, California	1986	110 MW
5	Coso Finance Partners	Inyo County, California	1988	92 MW
6	Coso Power Developers	Inyo County, California	1989	90 MW
7	Coso Energy Developers	Inyo County, California	1989	90 MW
8	Sonoma California Geothermal	Lake County, California	1983	78 MW
9	Dixie Valley	Churchill County, Nevada	2012	71 MW
10	Bottle Rock Power	Lake County, California	1985	55 MW

Geothermal power plants that came online most recently in CAISO

Newest first

#	Geothermal power plant	Location	Year online	Capacity
1	CD4	Mono County, California	2022	44 MW
2	Dixie Valley	Churchill County, Nevada	2012	71 MW
3	Mammoth G3	Mono County, California	1990	15 MW
4	Mammoth G2	Mono County, California	1990	15 MW
5	Coso Power Developers	Inyo County, California	1989	90 MW
6	Coso Energy Developers	Inyo County, California	1989	90 MW
7	Aidlin Geothermal Power Plant	Sonoma County, California	1989	25 MW
8	Coso Finance Partners	Inyo County, California	1988	92 MW
9	Geothermal 2	Sonoma County, California	1986	110 MW
10	Geysers Unit 5-20	Sonoma County, California	1985	1,236 MW

The developer behind each project is on paid plans. See plans

How Cleanview tracks geothermal power plants

Operating geothermal power plants come from the EIA's monthly survey of power plants. Planned projects come from the grid operators' interconnection queues. We research who is developing each one, since a queue lists a project company, not its owner.

Questions about geothermal power plants in CAISO

How many geothermal power plants are in CAISO?: CAISO has 15 operating utility-scale geothermal power plants with 2.2 GW of capacity, according to the EIA's monthly survey of power plants.
What is the largest geothermal power plant in CAISO?: Geysers Unit 5-20 in Sonoma County, California is the largest, at 1,236 MW. It came online in 1985.
How many geothermal power plants were built in CAISO in 2025?: 0 geothermal power plants came online in CAISO in 2025, with 0 MW of capacity.
Who is developing geothermal power plants in CAISO?: Interconnection queues list each project under a project company, not the developer behind it. Cleanview researches the developer of every project and has them on paid plans.