Marion
Williamson County, Illinois · EIA plant ID 976 · Operator: Southern Illinois Power Coop
×173 MW coal retired since 2020 (latest Nov 2020)
Nameplate249MWSummer 260 MW
Generators5in service
Net generation817GWh12 mo to Aug 2026
Capacity factor36%gas/coal/oil units, summer MW
Heat rate16,011Btu/kWhfossil units, electric fuel, HHV
First online1963Runs as intermediate
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) |
|---|---|---|---|
| 2001 | 1,364.3 | — | — |
| 2002 | 1,136.6 | — | — |
| 2003 | 1,429 | 42.5% | 11,356 |
| 2004 | 1,913.6 | 50.7% | 12,036 |
| 2005 | 1,835.3 | 48.7% | 12,766 |
| 2006 | 1,856.1 | 49.3% | 12,889 |
| 2007 | 1,781.2 | 47.3% | 12,426 |
| 2008 | 1,523.7 | 40.3% | 12,152 |
| 2009 | 1,734.2 | 46.0% | 11,663 |
| 2010 | 1,795.4 | 47.7% | 11,781 |
| 2011 | 1,860.3 | 49.4% | 11,928 |
| 2012 | 1,739.5 | 46.1% | 12,117 |
| 2013 | 1,719.4 | 45.6% | 11,609 |
| 2014 | 1,726.7 | 45.8% | 11,545 |
| 2015 | 1,800.9 | 47.8% | 11,440 |
| 2016 | 1,655.1 | 43.8% | 11,577 |
| 2017 | 1,636.1 | 43.4% | 11,482 |
| 2018 | 1,718.9 | 45.6% | 11,430 |
| 2019 | 1,652 | 43.9% | 11,531 |
| 2020 | 911.5 | 25.8% | 12,131 |
| 2021 | 669.4 | 29.4% | 13,289 |
| 2022 | 784.3 | 34.4% | 15,586 |
| 2023 | 708.9 | 31.1% | 15,303 |
| 2024 | 746.2 | 32.7% | 15,768 |
| 2025 | 767 | 33.7% | 16,030 |
Fuel capability
Gas-fired turbines (CT/GT/CA/CS) that can also burn liquid fuel. EIA-860 Schedule 3 for capability, EIA-923 for actual burn.
StatusLikely still dual fuel
Liquid fuel burned · 36 mo57,803 MMBtu
Last month with liquid burnApr 2026
Switch while operatingYes
Net summer MW on gas140
Net summer MW on oil140
Time gas → oilup to 1 h (EIA 1H)
Time oil → gasup to 1 h (EIA 1H)
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 | Conventional Steam Coal | ST | 33 | 40 | Jun 1963 | Operating | — | coming soon |
| 2 | Conventional Steam Coal | ST | 33 | 40 | Aug 1963 | Operating | — | coming soon |
| 3 | Conventional Steam Coal | ST | 33 | 40 | Sep 1963 | Operating | — | coming soon |
| 5 | Natural Gas Fired Combustion Turbine | GT | 75 | 70 | May 2003 | Operating | — | coming soon |
| 6 | Natural Gas Fired Combustion Turbine | GT | 75 | 70 | May 2003 | Operating | — | coming soon |
| 4 | Conventional Steam Coal | ST | 173 | 170 | Oct 1978 | Retired Nov 2020 | — | coming soon |
Owner / operator
Operator: Southern Illinois Power Coop. Ownership shares by in-service nameplate MW (EIA-860 Schedule 4; units not listed there are wholly owned by the operator).
| Southern Illinois Power Coop | 100.0% | 249 MW |
Nearby plants
Within 80 km.
| SV CSG Barrass Farms II LL | 2 MW | 15.1 km |
| East Marion IL 1, LLC | 4 MW | 15.3 km |
| Spillertown CSG 1 LLC | 5 MW | 16 km |
| SV CSG Gander Farms 1 A | 2 MW | 16.4 km |
| Blue Branch Solar | — | 17 km |
| Spillertown CSG 2 LLC | 5 MW | 17.2 km |