232nd largest plant in California · 2280th nationally
Marathon Bay Area Cogen is a natural gas power plant in California with a nameplate capacity of 114 MW. It generates roughly 624.2k MWh per year — enough to power about 59,450 average U.S. homes.
Its capacity factor of 63% puts it in the middle range — running steadily but not full-time. At 704 lb CO₂/MWh, its emission rate sits below the national grid average of roughly 800 lb/MWh.
Ghost bars are each month's theoretical maximum (114 MW nameplate × hours in the month). Filled bars are actual net generation reported to EIA Form 923. The gap between them is capacity factor made visible.
| Plant Name | Marathon Bay Area Cogen |
|---|---|
| Operator | Tesoro Marketing & Refining Co. Llc (Martinez) |
| City | Martinez |
| County | Contra Costa County |
| State | California |
| ZIP | 94553 |
| Coordinates | 38.02440, -122.05890 |
This plant highlighted in navy-ringed pin; other generators within 25 miles shown as fuel-colored dots.
| ID | Technology | Fuel | Capacity | Status | Online |
|---|---|---|---|---|---|
| TG1 | Natural Gas Fired Combined Cycle | Natural Gas | 40.0 MW | Operating | 1987 |
| TG2 | Natural Gas Fired Combined Cycle | Natural Gas | 40.0 MW | Operating | 1987 |
| TG3 | Natural Gas Fired Combined Cycle | Natural Gas | 33.5 MW | Operating | 1987 |
| Owner | Location | Share |
|---|---|---|
| Tesoro Refining And Marketing Co Llc | San Antonio, TX | 10000.0% |
Ownership reported to EIA Form 860. Percentages reflect reported generator-level ownership share, averaged when a plant has multiple generators.
| CO₂ | 219.6k metric tons |
|---|---|
| SO₂ | 1 metric tons |
| NOₓ | 590 metric tons |
| CO₂ Rate | 704 lb/MWh |
Annual totals and CO₂ rate reported by EPA eGRID for 2023. Reference averages are approximate U.S.-wide figures from the same dataset.
| NERC Region | WECC |
|---|---|
| Balancing Authority | California Independent System Operator |
Natural gas plants are the workhorse of the modern grid. Combined-cycle units achieve very high efficiency and can ramp up and down quickly to balance variable renewables. They emit roughly half the CO₂ per MWh of coal and far less of other pollutants, but they still release upstream methane during fuel extraction.