Coal power plant in Illinois, United States of America. Approximate location 37.619681, -88.952919.
CoalIllinoisUnited States of Americasubcritical
Marion Plant is a 392 MW coal power station in Illinois, United States of America. It is operated by Southern Illinois Power Cooperative Inc [100%]. Based on its capacity (estimated), it can supply roughly 491k homes (estimated). It ranks #1447 of 10,938 United States of America power plants by installed capacity. Commissioned in 1963, it is around 63 years old — an older, legacy facility. In context, coal supplies about 16.3% of United States of America's electricity; the national grid averages 384 gCO₂/kWh (43.0% low-carbon) (2025).
Plant data: WRI Global Power Plant Database (CC BY 4.0), id GEM_coa_marion_unite.
Known, modelled and calculated values are kept separate. Missing fields are shown as unavailable.
The public capacity above is the current source-record value. A 2026 tracker candidate lists 120 MW for Marion Plant, but it is not used as the public primary value until scope is verified (unit vs operating vs installed/project total).
The capacity and/or fuel fields on this page include a source-backed provenance label from GEM, an official registry, Wikidata, OSM, or a cross-source match.
capacity: GEM · 2026 · L100000103868; fuel: GEM GCPT
At 392 MW, Marion Plant is below the median coal plant in United States of America (558 MW). Technically it is described as subcritical. Coal plants burn pulverised coal to raise high-pressure steam for a turbine; they run as baseload but are the most carbon-intensive mainstream source and the first targeted for retirement or efficiency retrofits.
Capacity comparison computed from the WRI Global Power Plant Database; fuel-type context is general engineering background.
Installed capacity (MW), WRI Global Power Plant Database (CC BY 4.0).
Operated by Southern Illinois Power Cooperative Inc [100%].
This coal plant burns coal to raise high-pressure steam that spins a turbine-generator. It sits in a humid subtropical climate (Köppen Cfa) — Northern Hemisphere, latitude 37.6°N — which shapes how much energy it can produce and how its output varies through the year.
Monthly mean temperature
Heating degree-days here run 4% below the median power plant in this dataset — a proxy for how much extra energy heated equipment must replace through its surfaces in winter.
Climate heat-demand index: 48/100 — this site sits in the mid third of the power plants we cover by heating degree-days.
Climate normals: WorldClim 2.1 (1970–2000 monthly normals, 10 arc-min, CC BY 4.0); zone: Köppen-Geiger world climate classification (Kottek et al. 2006, 0.5° grid). Degree-days & heat-demand index computed by PowerAtlas — a modelled heat-demand proxy, not a measured site figure.
For a plant’s outdoor hardware — heat-recovery steam generators (HRSG), expansion joints, valves, flanges and their insulation — the local climate sets how fast unprotected steel and coatings degrade. This site sits in a moderately corrosive environment (estimated ISO 9223 class C3 — Medium), with humidity / wetness the leading environmental stress.
Higher environmental severity is exactly where protective removable insulation pays back most: a sheltered micro-climate slows corrosion, UV and thermal-cycling damage and extends outdoor hardware service life. This is an indicative site-climate context — not a condition assessment of any specific plant or operator.
Indicative estimate via the ISO 9223:2012 informative method (atmospheric corrosivity from temperature, time-of-wetness and airborne salinity), using WorldClim climate normals, the Köppen-Geiger class and coast distance. Indicative, not a measured corrosion rate.
The #474 largest coal power plant of 802 in United States of America by capacity.
United States of America has 802 coal power plants in this dataset, together about 621,194 MW of capacity.
Coordinates 37.619681, -88.952919 from WRI Global Power Plant Database (CC BY 4.0). View on OpenStreetMap.
Marion Plant is a 392 MW coal power plant in Illinois, United States of America, commissioned in 1963.
Its output is enough to supply roughly 490,560 homes (estimated).
Marion Plant is operated by Southern Illinois Power Cooperative Inc [100%].
