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- Combustion
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- Under construction
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- 10 · 100 · 1,000 MW
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- Combustion
- Wind & solar
- Under construction
- Operating
Marion: location and 4 exact-grade projects within 25 km. Basemap: Protomaps, © OpenStreetMap contributors, ODbL.
Marion
Power plant · Gas, combustion turbine
Key facts
Power plant · Gas, combustion turbineran 35% of 2025 Operating- Capacity
- Capacity: sourceEIA-860M · Open licenseMW
- Commissioned
- 1963
- Net generation, 2025
- 767,048 MWh
- Grid
- 161 kV, 67 kV to Southern Illinois Elec Coop (MISO)
- Location
- Williamson County, Illinois
- Operated by
- Southern Illinois Power CoopSourceEIA-860M Preliminary Monthly Electric Generator Inventory
Output
- Gas
- Coal
- Oil
Details
Who’s behind it
- Owner
- Southern Illinois Power CoopSource100.0%, EPA Greenhouse Gas Reporting Program — facility register with parent-company shares (Envirofacts pub_dim_facility; FLIGHT), as of 31 Dec 2023
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- Technology
- Gas, combustion turbine source: “Natural Gas Fired Combustion Turbine”
- Age
- 63 years since 1963
- Unused energy
- 1,414 GWh 2025Unused energyA lead, not a guarantee: MW × hours × (1 − capacity factor) for the latest year (EIA-923), gas, coal and oil plants only. Air-permit run-hour caps, heat rate (cost to run) and capacity-market or reliability obligations can rule it out.
- Heat rate
- 16,030 Btu/kWh 2025
All 7 attributes from EIA-860M Preliminary Monthly Electric Generator Inventory
| Attribute | Value |
|---|---|
| Gem |
|
| EPA greenhouse gas reporting (GHGRP) |
|
| Fuel burned (MMBtu), 2025 | 12,295,617 |
| Capacity factor, 2025 | 0.352 |
| Heat rate (Btu/kWh), 2025 | 16,029.8 |
| Net generation (MWh), 2025 | 767,048.0 |
| Balancing authority code | MISO |
Retirement
EIA-860M September 2026StatusSome generators have retired; the rest of the plant is still in service. As of EIA-860M for September 2026.- Capacity retired
- 173 MW
- Generators retired
- 1
- Capacity still in service
- 249 MW
| Generator | Technology | Nameplate | State | Date |
|---|---|---|---|---|
| 4 | Conventional Steam Coal | 173 MW | Retired | November 2020 |
Grid
EIA-860 2025Grid fieldsAs the plant reported them to EIA-860 for 2025 (Schedule 2).- Grid voltage at the plant
- 161 kV, 67 kV
- Transmission or distribution system owner
- Southern Illinois Elec Coop
- Balancing authority
- Midcontinent Independent Transmission System Operator, Inc..
- NERC region
- SERC
Transmission lines within 25 km (10)
Can the connection be reused?
A plant that retires usually leaves its substation, transmission connection and interconnection agreement behind, and those may be reusable by a new project at the same site. FERC Order No. 845 lets an interconnection customer use surplus interconnection service at an existing site, and some transmission providers' tariffs let a replacement resource take over a retiring unit's interconnection service, usually within a set time after the retirement. Whether any such right still exists here, who holds it and on what terms depends on the owner, the transmission provider and timing; this page does not establish any of that.
Timeline
- Stated Unit 4 scheduled to retire, 173 MW · EIA-860M
- In service · EIA-860M
Sources
6 sourcesSources EIA-860M · GEM · LBNL · EIA · EIA-860M Preliminary Monthly Electric Generator Inventory · EPA Greenhouse Gas Reporting Program — facility register with parent-company shares (Envirofacts pub_dim_facility; FLIGHT)
Sources
- EIA-860M Preliminary Monthly Electric Generator Inventory
- Global Energy Monitor — Global Integrated Power Tracker (unit-level power plants, eight technologies, all statuses)Global Integrated Power Tracker, Global Energy Monitor, September 2026 release (https://globalenergymonitor.org/projects/global-integrated-power-tracker), CC BY 4.0. Modified by Inframation: TransitionZero-sourced rows removed; statuses and technologies mapped to Inframation's vocabulary; figures aggregated. Copyright © Global Energy Monitor. Global Integrated Power Tracker, September 2026 release. Distributed under a Creative Commons Attribution 4.0 International License.
- LBNL — A Harmonized Geospatial Dataset of U.S. Transmission Lines: Linking FERC Form 1 and HIFLD, 1994-2024 (OEDI submission 8742)Yin, Nait Belaid & Heleno (2026), Lawrence Berkeley National Laboratory, OEDI, CC BY 4.0: A Harmonized Geospatial Dataset of U.S. Transmission Lines: Linking FERC Form 1 and HIFLD, 1994-2024. Modified by Inframation: HIFLD-side fields only, names re-cased, coordinates rounded.
- EIA Open Data bulk file — Electricity (ELEC.zip; monthly plant net generation and fuel consumption since 2001)Source: U.S. Energy Information Administration, Electricity bulk data (Form EIA-923 monthly plant series)
- EIA-860M Preliminary Monthly Electric Generator Inventory
- EPA Greenhouse Gas Reporting Program — facility register with parent-company shares (Envirofacts pub_dim_facility; FLIGHT)
Around this plant
Nearby
within 25 km| Project | Kind | Away | MW |
|---|---|---|---|
| Spillertown CSG 1 LLC Under construction | Solar | 16.0 km | 5 |
| Blue Branch Solar Under construction | Solar | 17.0 km | 35.9 |
| Spillertown CSG 2 LLC Under construction | Solar | 17.2 km | 5 |
| SV CSG Corbell Under construction | Solar | 17.9 km | 2 |