Marathon Bay Area Cogen
Natural gas power plant · Contra Costa County, California
Details
- Primary fuel
- Natural gas
- Technology
- Natural Gas Fired Combined Cycle
- Operator
- Tesoro Marketing & Refining Co. LLC (Martinez)
- County
- Contra Costa County
- Generating units
- 3
- Share of state capacity
- 0.11%
- Rank among natural gas plants in California
- #73 of 309
- EIA plant code
- 10342
Generating units
| Unit | Technology | Nameplate | Summer | Online | Status |
|---|---|---|---|---|---|
| TG1 | Natural Gas Fired Combined Cycle | 40 MW | 35 MW | 1987 | Operating |
| TG2 | Natural Gas Fired Combined Cycle | 40 MW | 35 MW | 1987 | Operating |
| TG3 | Natural Gas Fired Combined Cycle | 34 MW | 34 MW | 1987 | Operating |
Nameplate is the maximum rated output; summer capacity is what the unit can reliably deliver on a hot day, which is typically lower.
Similarly sized plants in California
| Border Hybrid Energy Center | Natural gas | 115 MW |
| Daggett 1 | Battery storage | 114 MW |
| Separator (Etiwanda) BESS | Battery storage | 113 MW |
| Valentine Solar, LLC | Solar | 111 MW |
About this data
From EIA’s inventory of operable generators, May 2026 release. Capacity is nameplate — the maximum rated output of the equipment, not what the plant actually generates over a year, which depends on how often it runs. A 114 MW solar plant and a 114 MW nuclear plant have the same entry here and produce very different amounts of electricity.
“In service since” is the earliest in-service date among the units still listed, so a site rebuilt around newer equipment can read as younger than the site itself. All California power plants · What California actually generates