Marion
Natural gas and coal power plant in Williamson County, Illinois. 249 MW of nameplate capacity across 5 generators, operated by Southern Illinois Power Coop.
Also known as Marion Power Plant · EIA plant 976
Analyst: free account, 1 question a day.
Key facts
- Capacity
- 249 MWNatural gas 150.0 · Coal 99.0
- Generators
- 5 operatingEIA-860M, August 2026
- Operating since
- June 1963First generator online
- Operator
- Southern Illinois Power CoopEIA operator ID 17632
- Grid
- MISOBalancing authority MISO
- Price nodes
- 3 MISO nodesResource nodes with prices
- Location
- Williamson County, IL37.6197, −88.9531
- EIA plant ID
- 976EIA plant page
Data as of EIA-860M August 2026 (published 2026-09-24). Capacity is nameplate, not live output.
How much power Marion produces
Free · EIA-923Net generation, 2025
767 GWh
767,048 MWh, final
Capacity factor, 2025
35.2%
2024: 34.1%
January to July 2026
487 GWh
Provisional
Range, 2015 to 2025
0.7–1.8
TWh a year. Low 2023, high 2015
| Year | Net generation, MWh | Capacity factor | Months reported |
|---|---|---|---|
| 2000 | 1,357,960 | Not reported | 12 of 12 |
| 2001 | 1,364,295 | Not reported | 12 of 12 |
| 2002 | 1,136,616 | Not reported | 12 of 12 |
| 2003 | 1,429,045 | Not reported | 12 of 12 |
| 2004 | 962,610 | Not reported | 6 of 12 |
| 2005 | 1,835,312 | Not reported | 12 of 12 |
| 2006 | 1,856,060 | Not reported | 12 of 12 |
| 2007 | 1,781,203 | Not reported | 12 of 12 |
| 2008 | Not reported | Not reported | 0 of 12 |
| 2009 | Not reported | Not reported | 0 of 12 |
| 2010 | 1,795,382 | Not reported | 12 of 12 |
| 2011 | 1,860,303 | 50.3% | 12 of 12 |
| 2012 | 1,739,521 | 46.9% | 12 of 12 |
| 2013 | 1,719,444 | 46.5% | 12 of 12 |
| 2014 | Not reported | Not reported | 0 of 12 |
| 2015 | 1,800,859 | 48.7% | 12 of 12 |
| 2016 | 1,655,061 | 44.6% | 12 of 12 |
| 2017 | 1,636,123 | 44.3% | 12 of 12 |
| 2018 | 1,718,914 | 46.5% | 12 of 12 |
| 2019 | 1,652,019 | 44.7% | 12 of 12 |
| 2020 | 911,493 | Not reported | 12 of 12 |
| 2021 | 459,783 | 31.7% | 8 of 12 |
| 2022 | 784,259 | 36.0% | 12 of 12 |
| 2023 | 708,926 | 32.5% | 12 of 12 |
| 2024 | 746,246 | 34.1% | 12 of 12 |
| 2025 | 767,048 | 35.2% | 12 of 12 |
| 2026 (provisional, partial year) | 486,780 | 38.4% | 7 of 7 |
* 2026 covers January to July and is provisional. Capacity factor is net generation divided by nameplate capacity times the hours of each reported month.
Power prices and basis
Free account · MISOEmissions
Free · EPA CAMPDCO₂, 2025
1.10M
US short tons. 2024: 1.16M
SO₂, 2025
2,285
US short tons
NOx, 2025
376
US short tons
CO₂ per MWh, calculated
1.44 t
About 2,878 lb per MWh
3 of 3 EPA units reported CO₂ in 2025 (123, 4, 5, 6), matched to EIA plant 976 through the EPA–EIA crosswalk. The per-MWh rate is EPA CO₂ divided by EIA-923 net generation. The two reporting boundaries can differ.
Water use
Free · EIA-923 cooling, USGSWithdrawal, 2024
49,595
million gallons
Consumption, 2024
993
million gallons
Source
Lake Egypt
Surface, Fresh. Once-through with cooling pond
Watershed stress
Moderate · 0.404
USGS SUI, HUC12 Lake of Egypt-South Fork Saline River
12 of 12 cooling months report withdrawal. SUI of the HUC12 containing the plant. Cooling-pond plants report water circulated through the pond as withdrawal, so withdrawal is far above consumption. Blank volumes are unreported, not zero.
Generators
Free · EIA-860M| Generator | Technology | Nameplate MW | Online since |
|---|---|---|---|
| 1 | Conventional Steam Coal | 33.0 | June 1963 |
| 2 | Conventional Steam Coal | 33.0 | August 1963 |
| 3 | Conventional Steam Coal | 33.0 | September 1963 |
| 5 | Natural Gas Fired Combustion Turbine | 75.0 | May 2003 |
| 6 | Natural Gas Fired Combustion Turbine | 75.0 | May 2003 |
Ownership and offtake
ProOwnership and offtake are part of Pro
Owners and their shares, parent companies, and power purchase agreements with their buyers. EIA-860M lists Southern Illinois Power Coop as the operator, which is not always the owner.
Modeled data
ProPro adds modeled values for this plant. Everything above stays free.
Generation potential vs reported
Monthly potential at seasonal net capability, next to EIA-923 output. Shows how much of the plant's capability was used.
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Power plants near Marion
Questions about Marion
How much power does Marion produce?
Marion reported 767,048 MWh (767 GWh) of net generation in 2025, a 35.2% capacity factor on 249 MW of nameplate capacity. From January to July 2026 it reported 487 GWh, which is provisional.
Where is Marion?
Marion is in Williamson County, Illinois, at 37.6197, −88.9531. It is in the Midcontinent Independent Transmission System Operator, Inc.. balancing area (MISO).
Who operates Marion?
EIA-860M for August 2026 lists Southern Illinois Power Coop as the operator (EIA operator ID 17632). The operator is not always the owner.
Is Marion a natural gas or a coal plant?
Both. Natural gas capacity totals 150 MW and coal capacity totals 99 MW.
When did Marion start operating?
Its first generator began operating in June 1963, according to EIA-860M.
Does InfraMap have power prices for Marion?
Yes. InfraMap has MISO day-ahead and real-time prices at 3 price nodes linked to Marion, with the hub price and node-to-hub basis. Prices are free with an InfraMap account; pricing node names are part of InfraMap Pro.
Sources
- EIA-860 2025 (final) and EIA-860M August 2026: plant, generators, capacity, operator and location
- EIA-923 monthly net generation, 2000 to July 2026 (2026 provisional)
- EPA CAMPD annual emissions through the EPA–EIA crosswalk, 1995 to 2025
- MISO day-ahead and real-time prices; node and hub assignments as of 2026-10-05
- EIA-923 cooling water 2024 and the USGS surface water supply and use index, Water years 2010-2020 (Oct 2009 to Sep 2020), mean of monthly values
- Plant names from OpenStreetMap, © OpenStreetMap contributors (ODbL)
Page updated 2026-10-04 from the InfraMap data build. Methodology · Data sources · EIA plant page