# Calistoga Power Plant

CAISO Geothermal · https://askthegrid.com/assets/facilities/calistoga-power-plant

Calistoga Power Plant is a geothermal facility with 176.4 MW of EIA-reported nameplate capacity in Lake County, California, registered as EIA Plant ID 50066. Calistoga Unit 19 is part of The Geysers, which Calpine describes as the largest complex of geothermal power facilities in the world. The facility uses dry or superheated steam and contributes to The Geysers’ role in supplying about half of California’s in-state geothermal power.

## Key facts

- Technology: Geothermal
- Power capacity: 176.4 MW
- Operating status: operating

## Grid and market context

- ISO/RTO: CAISO
- Balancing authority: CISO (CAISO)

## Source-backed facts

- Owner logo domain: calpine.com — Geothermal - Calpine · confidence: medium
- Identifiers: [{"value":"50066","system":"EIA plant code"},{"value":"50073","system":"FERC EIA directory ID"},{"value":"UNT1","system":"EIA/FERC generator ID"},{"value":"UNT2","system":"EIA/FERC generator ID"},{"value":"CISO (CAISO)","system":"ISO/RTO"},{"value":"ER99-1983-000","system":"FERC MBR docket"},{"value":"81-AFC-01","system":"California Energy Commission docket"},{"value":"GEYSERS CALISTOGA AGGREGATE","system":"CAISO market resource"},{"value":"Calpine Energy Services","system":"CAISO scheduling coordinator"}] — ALSTON&BIRD LLP · confidence: medium
- Identifiers: [{"value":"50066","system":"EIA plant code"},{"value":"50073","system":"FERC EIA directory ID"},{"value":"UNT1","system":"EIA/FERC generator ID"},{"value":"UNT2","system":"EIA/FERC generator ID"},{"value":"CISO (CAISO)","system":"ISO/RTO"},{"value":"ER99-1983-000","system":"FERC MBR docket"},{"value":"81-AFC-01","system":"California Energy Commission docket"},{"value":"GEYSERS CALISTOGA AGGREGATE","system":"CAISO market resource"},{"value":"Calpine Energy Services","system":"CAISO scheduling coordinator"}] — Curtailed · confidence: medium
- Identifiers: [{"value":"50066","system":"EIA plant code"},{"value":"50073","system":"FERC EIA directory ID"},{"value":"UNT1","system":"EIA/FERC generator ID"},{"value":"UNT2","system":"EIA/FERC generator ID"},{"value":"CISO (CAISO)","system":"ISO/RTO"},{"value":"ER99-1983-000","system":"FERC MBR docket"},{"value":"81-AFC-01","system":"California Energy Commission docket"},{"value":"GEYSERS CALISTOGA AGGREGATE","system":"CAISO market resource"},{"value":"Calpine Energy Services","system":"CAISO scheduling coordinator"}] — 2026 NQC List · confidence: medium
- Identifiers.7: {"value":"GEYSERS CALISTOGA AGGREGATE","system":"CAISO market resource"} — 2026 NQC List · confidence: high
- Identifiers.7: {"value":"GEYSERS CALISTOGA AGGREGATE","system":"CAISO market resource"} — Curtailed · confidence: high
- Identifiers.8: {"value":"Calpine Energy Services","system":"CAISO scheduling coordinator"} — ALSTON&BIRD LLP · confidence: medium
- Parties.1: {"relationship":"Plant utility/operator","name":"Geysers Power Co LLC","official_url":"https://geysers.com/"} — The Geysers · confidence: medium
- Parties.3: {"relationship":"CAISO scheduling coordinator","name":"Calpine Energy Services","official_url":"https://www.calpine.com/"} — ALSTON&BIRD LLP · confidence: medium
- Product url: https://toshiba.com/taes/geothermal-power-solutions/ — Geothermal Power Solutions | TAES · confidence: medium
- Product family: Geothermal Steam Turbine — Geothermal Power Solutions | TAES · confidence: medium
- Equipment models.0: {"manufacturer_domain":"toshiba.com","product_url":"https://toshiba.com/taes/geothermal-power-solutions/","count":2,"unit_mw":88.2,"name":"Toshiba geothermal steam turbine"} — Geothermal Power Solutions | TAES · confidence: medium
- Quality notes: ["The 176.4 MW figure applies to the EIA plant aggregate and its two generating units; the CEC Unit 19 record is a separate component-level record with differing capacity figures, including 97 MW listed project capacity and approximately 69 MW supplied as of January 2021.","The FERC record shows a March 1984 operating month for EIA plant 50066, while the CEC identifies April 1984 as Unit 19’s commercial-operation month. These dates should not be treated as identical component and aggregate records without further reconciliation.","The $77.9 million amount is acquisition consideration for Calistoga Power Plant, the Silverado steam fields, and related assets; it is not identified as construction or project financing.","The cited records identify continued operation and an oxidizer-blower replacement but do not identify a plant expansion, retirement, or repowering event."] — Asset Appendix Report - MBR Portal - FERC · confidence: medium
- Quality notes: ["The 176.4 MW figure applies to the EIA plant aggregate and its two generating units; the CEC Unit 19 record is a separate component-level record with differing capacity figures, including 97 MW listed project capacity and approximately 69 MW supplied as of January 2021.","The FERC record shows a March 1984 operating month for EIA plant 50066, while the CEC identifies April 1984 as Unit 19’s commercial-operation month. These dates should not be treated as identical component and aggregate records without further reconciliation.","The $77.9 million amount is acquisition consideration for Calistoga Power Plant, the Silverado steam fields, and related assets; it is not identified as construction or project financing.","The cited records identify continued operation and an oxidizer-blower replacement but do not identify a plant expansion, retirement, or repowering event."] — 2023 Annual Compliance Report - Calistoga (U19) · confidence: medium
- Financing summary: No separate construction or project-financing facility, lender, or financing terms are identified in the cited CEC and SEC records. Calpine’s SEC disclosure states that on 1999-10-19 it purchased the Calistoga Power Plant, Silverado steam fields, and related assets from FPL Energy and Caithness Corporation for $77.9 million; this is sale consideration for an acquisition package, not project financing. — Calpine Corporation Form 8-K · confidence: high
- Timeline.7: {"event":"Calpine acquisition","date":"1999-10-19","detail":"Calpine purchased the Calistoga Power Plant, Silverado steam fields, and related assets from FPL Energy and Caithness Corporation for $77.9 million."} — Calpine Corporation Form 8-K · confidence: high
- Timeline.9: {"event":"Operational status and maintenance","date":"2023-2024","detail":"The plant remained operational during the 2023 reporting period; the compliance record later added an oxidizer-blower replacement closeout and as-built package dated April 2024."} — 2023 Annual Compliance Report - Calistoga (U19) · confidence: high
- Quality notes.2: The $77.9 million amount is acquisition consideration for Calistoga Power Plant, the Silverado steam fields, and related assets; it is not identified as construction or project financing. — Asset Appendix Report - MBR Portal - FERC · confidence: high
- Quality notes.3: The cited records identify continued operation and an oxidizer-blower replacement but do not identify a plant expansion, retirement, or repowering event. — Calpine Corporation Form 8-K · confidence: medium
- Quality notes.3: The cited records identify continued operation and an oxidizer-blower replacement but do not identify a plant expansion, retirement, or repowering event. — 2023 Annual Compliance Report - Calistoga (U19) · confidence: medium
- Grid role: Baseload geothermal generation — Calistoga Geothermal Project - Unit 19 | California Energy Commission · confidence: medium

## Timeline

- 1982-02 — CEC certification
  The California Energy Commission certified Unit 19, originally known as Occidental Geothermal Power Plant No. 1.
  Source: Calistoga Geothermal Project - Unit 19 | California Energy Commission (https://www.energy.ca.gov/powerplant/steam-turbine/calistoga-geothermal-project-unit-19)
- 1996-11-04 — CEC license-transfer approval
  The CEC approved transfer of the license from First Trust of California, National Association to Santa Fe Geothermal, Inc.
  Source: Calistoga Geothermal Project - Unit 19 | California Energy Commission (https://www.energy.ca.gov/powerplant/steam-turbine/calistoga-geothermal-project-unit-19)
- 1997-04-18 — CEC transfer to Calistoga Geothermal Partners
  The CEC approved transfer from Santa Fe Geothermal, Inc. to Calistoga Geothermal Partners, LP; ESI subsequently renamed the operating entity Silverado Geothermal Resources, Inc., which sold the plant to Calistoga Geothermal Partners.
  Source: Calistoga Geothermal Project - Unit 19 | California Energy Commission (https://www.energy.ca.gov/powerplant/steam-turbine/calistoga-geothermal-project-unit-19)

## Sources

- [Geothermal - Calpine](https://www.calpine.com/clean-and-reliable-power/our-assets/geothermal/) — calpine.com · tier other
- [Asset Appendix Report - MBR Portal - FERC](https://mbrweb.ferc.gov/SearchMBRAssetAppendix/AssetAppendixDetails?AssetAppendixId=11507) — mbrweb.ferc.gov · tier regulatory
- [Source](https://www.caiso.com/documents/july22_2008largegeneratorinterconnectionagreementamonggeyserspowercompany_pg_eandcaisoindocketno_er08-1292.pdf) — caiso.com · tier other
- [Curtailed](https://www.caiso.com/documents/curtailed-non-operational-generator-am-report-20250505.xlsx) — caiso.com · tier other
- [2026 NQC List](https://www.caiso.com/documents/net-qualifying-capacity-report-for-compliance-year-2026.xlsx) — caiso.com · tier other
- [Calistoga Geothermal Project - Unit 19 | California Energy Commission](https://www.energy.ca.gov/powerplant/steam-turbine/calistoga-geothermal-project-unit-19) — energy.ca.gov · tier regulatory
- [The Geysers](https://geysers.com/) — geysers.com · tier other
- [About The Geysers](https://geysers.com/about/) — geysers.com · tier other
- [2023 Annual Compliance Report - Calistoga (U19)](https://efiling.energy.ca.gov/GetDocument.aspx?tn=257433) — efiling.energy.ca.gov · tier regulatory
- [Geothermal Power Solutions | TAES](https://toshiba.com/taes/geothermal-power-solutions/) — toshiba.com · tier other
- [Calpine Corporation Form 8-K](https://www.sec.gov/Archives/edgar/data/916457/000089161801501784/f75423e8-k.htm) — sec.gov · tier regulatory
- [DOCKETED](https://efiling.energy.ca.gov/GetDocument.aspx?tn=227761&DocumentContentId=59116) — efiling.energy.ca.gov · tier regulatory

## Data quality

- The 176.4 MW figure applies to the EIA plant aggregate and its two generating units; the CEC Unit 19 record is a separate component-level record with differing capacity figures, including 97 MW listed project capacity and approximately 69 MW supplied as of January 2021. The FERC record shows a March 1984 operating month for EIA plant 50066, while the CEC identifies April 1984 as Unit 19’s commercial-operation month. These dates should not be treated as identical component and aggregate records without further reconciliation. The cited records identify continued operation and an oxidizer-blower replacement but do not identify a plant expansion, retirement, or repowering event.

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