South Texas Project
Matagorda County, Texas · EIA plant ID 6251 · Operator: STP Nuclear Operating Co
Nameplate2,709MWSummer 2,580 MW
Generators2in service
Net generation20,254GWh12 mo to Aug 2026
Capacity factor90%nuclear units, summer MW
Heat rate—thermal plants only
First online1988
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), nuclear 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.
Heat rate applies to fuel-burning (thermal) units only.
Annual data table
| Year | Net GWh | Capacity factor | Heat rate (Btu/kWh) |
|---|---|---|---|
| 2001 | 19,840.6 | 89.6% | — |
| 2002 | 19,049.6 | 86.0% | — |
| 2003 | 15,688.5 | 70.0% | — |
| 2004 | 21,372 | 95.0% | — |
| 2005 | 19,789.3 | 88.2% | — |
| 2006 | 21,368.3 | 95.3% | — |
| 2007 | 22,109.3 | 98.6% | — |
| 2008 | 21,492.7 | 95.6% | — |
| 2009 | 21,356.1 | 95.2% | — |
| 2010 | 21,126.8 | 94.2% | — |
| 2011 | 20,365.9 | 90.8% | — |
| 2012 | 18,544.1 | 82.5% | — |
| 2013 | 17,827.9 | 79.5% | — |
| 2014 | 20,651.7 | 92.1% | — |
| 2015 | 19,400.6 | 86.5% | — |
| 2016 | 21,694.3 | 96.5% | — |
| 2017 | 21,581.5 | 96.2% | — |
| 2018 | 20,687.6 | 92.3% | — |
| 2019 | 21,993.3 | 98.1% | — |
| 2020 | 21,958.8 | 96.9% | — |
| 2021 | 20,855 | 92.3% | — |
| 2022 | 21,919.9 | 97.0% | — |
| 2023 | 21,787.1 | 96.4% | — |
| 2024 | 18,926.5 | 83.5% | — |
| 2025 | 21,782.1 | 96.4% | — |
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 |
|---|---|---|---|---|---|---|---|---|
| 1 | Nuclear | ST | 1,354.3 | 1,300 | Aug 1988 | Operating | — | coming soon |
| 2 | Nuclear | ST | 1,354.3 | 1,280 | Jun 1989 | Operating | — | coming soon |
Owner / operator
Operator: STP Nuclear Operating Co. Ownership shares by in-service nameplate MW (EIA-860 Schedule 4; units not listed there are wholly owned by the operator).
| Constellation Nuclear | 44.0% | 1,192 MW |
| City of San Antonio - (TX) | 40.0% | 1,083 MW |
| Austin Energy | 16.0% | 433 MW |
Nearby plants
Within 80 km.
| Duffy BESS | — | 7.6 km |
| Eldora Energy LLC | — | 10.7 km |
| Isaac Solar | — | 10.8 km |
| Regis Palacios | 10 MW | 16.5 km |
| Peyton Creek Wind Farm LLC | 151 MW | 18.8 km |
| Ventures BESS | — | 20.6 km |