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113.5 MW Natural Gas operating in Contra Costa, CA — California Independent System Operator
113.5 MW
Nameplate Capacity
3
Generators
units
Natural Gas Fired Combined Cycle
Technology
1987
Operating Since
Coordinates
38.0244, -122.0589
County
Contra Costa, CA
Nearby Plants
| Field | EIA | GEM | Wikidata |
|---|---|---|---|
| Operator | Tesoro Marketing & Refining Co. LLC (Martinez) | — | — |
| Owner(s) | Tesoro Refining and Marketing Co LLC | — | — |
| Status | Operating | — | — |
Marathon Bay Area Cogen is a natural gas-fired combined cycle power plant located in Contra Costa County, California. The plant has a total capacity of 113.5 MW distributed across three generators. It began operating in 1987 and is owned and operated by Tesoro Marketing & Refining Co. LLC (Martinez). The plant operates within the California Independent System Operator (CAISO) balancing authority and the Western Electricity Coordinating Council (WECC) NERC region.
In the most recent year with available data, Marathon Bay Area Cogen generated 585,121 MWh of electricity, achieving a capacity factor of 64.2%. In terms of size, the plant ranks 72nd out of 76 power plants in California and 907th out of 945 plants nationally.
Generated from EIA, GEM, and public data sources
ISO/RTO
CAISO
Market
ISO/RTO Member
NERC Region
WECC — Western Electricity Coordinating Council
Balancing Authority
California Independent System Operator (CISO)
Grid Voltage
230.0 kV
Regulatory Status
NR — Non-Regulated
Entity Type
Independent Power Producer
Sector
IPP CHP
56.3K MWh
Latest Month
585.1K MWh
Annual Generation
64.2%
Capacity Factor
CO₂ Intensity
704 lb/MWh
NOx
2 lb/MWh
SO₂
0.003 lb/MWh
CH₄
0.013 lb/MWh
N₂O
0.001 lb/MWh
Capacity Factor
62.8%
Annual Net Gen
624 GWh
CO₂eq
704 lb/MWh
Subregion
WECC California
2013
$965/kW
Est. Construction Cost
Total estimated cost: $109.5M
Market Position
ISO/RTO Market
CAISO
LMP Node
FOSTERW_7_N004
Pricing Hub
TH_NP15_GEN-APND
Location Type
Pricing Node
Node Source
EIA-860 direct report
Last updated 2026-03-26
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