Mariposa Energy Project
Diamond Generating CorporationAlameda County
Mariposa Energy Project is a natural gas-fired power facility with 199.6 MW of EIA-reported operating capacity in Alameda County, California, registered as EIA Plant ID 57483. Diamond Generating Corporation owns and operates the plant. The plant's generating configuration is four GE LM6000 PC-SPRINT natural-gas-fired simple-cycle combustion turbine generators. Commercial operation began in October 2011. The facility interconnects at Kelso Substation at 230 kV.
Mapped infrastructure geometry associated with this asset.
Natural Gas Fired Combustion Turbine
Mariposa Energy Project is operating.
230 kV · Pacific Gas and Electric Company (PG&E)
EIA plant 57483 · Inventory for Sep 2026.
| Generator | Technology | Status | Power (MW) | Energy (MWh) |
|---|---|---|---|---|
| CTG1 | Natural Gas Fired Combustion Turbine | Operating | 49.9 | Unknown |
| CTG2 | Natural Gas Fired Combustion Turbine | Operating | 49.9 | Unknown |
| CTG3 | Natural Gas Fired Combustion Turbine | Operating | 49.9 | Unknown |
| CTG4 | Natural Gas Fired Combustion Turbine | Operating | 49.9 | Unknown |
Similar plants ranked by technology, capacity, and distance.
Current generator records and technology attributes reported through EIA-860.
| Generator | Capacity | Technology | Operation | Status |
|---|---|---|---|---|
| CTG1 | 49.9 MW 49.9 MW summer | Natural Gas Fired Combustion Turbine GT | Oct 2012 | Operating |
| CTG2 | 49.9 MW 49.9 MW summer | Natural Gas Fired Combustion Turbine GT | Oct 2012 | Operating |
| CTG3 | 49.9 MW 49.9 MW summer | Natural Gas Fired Combustion Turbine GT | Oct 2012 | Operating |
| CTG4 | 49.9 MW 49.9 MW summer | Natural Gas Fired Combustion Turbine GT | Oct 2012 | Operating |
Monthly EIA generation history and recent market-resource behavior where linked telemetry is available.
Deterministic links to ERCOT market resources, price records, outage disclosures, queue records, and nearby infrastructure. Candidate joins remain labeled until corroborated.
Source-backed project transactions, agreements, land records, permits, and environmental disclosures. Portfolio and adjacent-project facts remain explicitly scoped.
Parties, market resources, and identifiers tied to this asset, with owner, operator, developer, EPC, compliance provider, and interconnecting entity roles kept separate.
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Project milestones and public references behind the asset profile.
Mariposa Energy LLC filed an Application for Certification with the California Energy Commission to construct and operate the natural-gas-fired simple-cycle peaking facility.
CAISO
CAISO · Alameda County
Monthly generation is reported through EIA-923. Capacity factor uses the current EIA nameplate capacity and is shown only for complete calendar years.
| Largest reported plants | Capacity | State | |
|---|---|---|---|
| Mariposa Energy ProjectCurrent | 199.6 MW | CA | |
| Indigo Energy Facility | 149.7 MW | CA | |
| Larkspur Energy Facility | 99.8 MW | CA |
Portfolio membership follows the latest EIA-860 reporting entity. It does not imply ultimate ownership.
View full reporting portfolioThe Bay Area Air Quality Management District's Final Determination of Compliance described Mariposa Energy LLC as the entity that would construct, own, and operate the project, with Diamond Generating Corporation as its owner and Mitsubishi Corporation as ultimate corporate parent.
The California Energy Commission certified the Mariposa Energy Project under Docket 09-AFC-03.
The CEC states that the facility began commercial operation in October 2011.
EIA-860 lists generator CTG1, generator CTG2, generator CTG3, generator CTG4 with this operating date.
Answered from the published record above. Questions whose inputs this profile does not carry are omitted rather than estimated.
Mariposa Energy Project reports 199.6 MW natural gas of operating nameplate capacity. These technology ratings do not establish a common export limit. Source: EIA Sep 2026.
Mariposa Energy Project is a Natural Gas Fired Combustion Turbine facility in Alameda County, CA, participating in the CAISO market.
Mariposa Energy Project is in Alameda County, CA, inside the CAISO balancing area.
Mariposa Energy Project is operated by Diamond Generating Corporation according to the EIA generator inventory. Reporting membership does not by itself establish ultimate ownership.
Mariposa Energy Project reported 30.1 GWh over the twelve months to 2026-07. Figures are net generation as filed to EIA-923.
Mariposa Energy Project interconnects at Kelso Substation, on the Pacific Gas and Electric Company (PG&E) system.
By capacity, Mariposa Energy Project ranks #250 of 829 operating plants of the same technology nationally. It ranks #15 of 136 in CA.
Plants within 25 km, nearest first, regardless of technology. Proximity is straight-line distance between mapped plant coordinates; it does not by itself establish a shared point of interconnection.