Mark One Power Station
Brazoria County, Texas · EIA plant ID 65372 · Operator: City of San Antonio - (TX)
Nameplate484MWSummer 357 MW
Generators8in service
Net generation416GWh12 mo to Aug 2026
Capacity factor13%gas/coal/oil units, summer MW
Heat rate10,586Btu/kWhfossil units, electric fuel, HHV
First online2022Runs as peaking
The 12-month figures include preliminary EIA-923 months, which EIA revises. Final data runs through Dec 2025.
Monthly net generation
EIA-923, all units at the plant. Net of station use; storage can go negative.
FinalPreliminary
Capacity factor by year
Net MWh ÷ (summer MW × hours), gas/coal/oil units. Each year uses that year's EIA-860 ratings; the hollow dot is the latest 12 months.
Heat rate by year
Electric fuel MMBtu × 1000 ÷ net MWh (Btu/kWh, HHV), fossil units only; CT + CA counted as one combined-cycle block.
Annual data table
| Year | Net GWh | Capacity factor | Heat rate (Btu/kWh) |
|---|---|---|---|
| 2022 | 34.3 | 8.8% | 10,621 |
| 2023 | 115.1 | 4.9% | 10,084 |
| 2024 | 329.3 | 12.9% | 10,196 |
| 2025 | 352.7 | 11.3% | 10,477 |
Generators
EIA-860 (annual) with EIA-860M updates through Sep 2026. EIA-923 reports generation by plant, prime mover and fuel, not by unit, so unit-level output isn't shown.
| Gen ID | Technology | Prime mover | Nameplate MW | Summer MW | Online | Status | Planned retirement | OEM / model |
|---|---|---|---|---|---|---|---|---|
| CTG-1 | Natural Gas Fired Combustion Turbine | GT | 60.5 | 44.6 | Nov 2022 | Operating | — | coming soon |
| CTG-2 | Natural Gas Fired Combustion Turbine | GT | 60.5 | 44.6 | Nov 2022 | Operating | — | coming soon |
| CTG-3 | Natural Gas Fired Combustion Turbine | GT | 60.5 | 44.6 | Nov 2022 | Operating | — | coming soon |
| CTG-4 | Natural Gas Fired Combustion Turbine | GT | 60.5 | 44.6 | Nov 2022 | Operating | — | coming soon |
| CTG-5 | Natural Gas Fired Combustion Turbine | GT | 60.5 | 44.6 | Nov 2022 | Operating | — | coming soon |
| CTG-6 | Natural Gas Fired Combustion Turbine | GT | 60.5 | 44.6 | Nov 2022 | Operating | — | coming soon |
| CTG-7 | Natural Gas Fired Combustion Turbine | GT | 60.5 | 44.6 | Oct 2024 | Operating | — | coming soon |
| CTG-8 | Natural Gas Fired Combustion Turbine | GT | 60.5 | 44.6 | Oct 2024 | Operating | — | coming soon |
Owner / operator
Operator: City of San Antonio - (TX). Ownership shares by in-service nameplate MW (EIA-860 Schedule 4; units not listed there are wholly owned by the operator).
| Mark One Generating, LLC | 100.0% | 484 MW |
Nearby plants
Within 80 km.
| Winmil Clean Energy Center (BESS) | 12 MW | 0.2 km |
| Myrtle Storage | 150 MW | 0.3 km |
| Myrtle Solar, LLC | — | 0.4 km |
| Gambit Energy Storage - Angleton Storage | 100 MW | 6.7 km |
| Angleton | 10 MW | 6.7 km |
| Cradle Solar | — | 7.6 km |