Joliet 9 — United States of America

Joliet 9 is a 360.4 MW gas power station in Illinois, United States of America. It is operated by Midwest Generations EME LLC. Based on its capacity (estimated), it can supply roughly 406k homes (estimated). It ranks #1439 of 10,884 United States of America power plants by installed capacity. Commissioned in 1959, it is around 67 years old — an older, legacy facility. In context, gas supplies about 40.0% 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 USA0000874.

Data provenance

Source of the capacity and fuel values:

capacity: Wikidata P2109; fuel: WRI GPPD

In context: how this plant compares

At 360.4 MW, Joliet 9 is well above the median gas plant in United States of America (121.2 MW). Technically it is described as Steam. Gas plants burn natural gas either in open-cycle turbines for fast peaking, or in combined-cycle units that recover exhaust heat in an HRSG to reach roughly 55–62% efficiency — the cleanest-burning fossil option.

Capacity comparison computed from the WRI Global Power Plant Database; fuel-type context is general engineering background.

Key facts

Generation trend

1,303 GWh in 2013 and 44 GWh in 2017 (−97%)

Highest and lowest year

2013: 1,303 GWh; 2017: 44 GWh

Share of United States of America gas capacity

less than 0.1% of 789,950 MW across 2,165 plants in this dataset

Age among peers

43 of 1,973 dated gas plants in United States of America are older

Calculated from the capacity and generation records in this dataset (WRI Global Power Plant Database (CC BY 4.0)).

Reported generation trend

Annual generation (GWh), WRI Global Power Plant Database (CC BY 4.0).

Owner

Operated by Midwest Generations EME LLC.

Local climate & thermal context

This gas plant burns natural gas in a turbine — often in a combined-cycle setup — to generate electricity. It sits in a hot-summer humid continental climate (Köppen Dfa) — Northern Hemisphere, latitude 41.5°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 38% above 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: 73/100 — this site sits in the top third of the power plants we cover by heating degree-days.

A gas turbine here also runs ~0% below its ISO (15°C) rating at this annual mean (typical CCGT curve, estimate).

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.

Site climate & environmental severity

This site sits in a moderately corrosive environment (estimated ISO 9223 class C3 — Medium), with thermal cycling the leading environmental stress.

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.

How it compares & nearby plants

The #710 largest gas power plant of 2165 in United States of America by capacity.

United States of America has 2165 gas power plants in this dataset, together about 789,950 MW of capacity.

Nearby power plants

• Joliet 29 · Gas · 1,320 MW · Illinois
• Jake Energy Storage Center · Storage · 19.8 MW · Illinois
• Joliet 29 Generating Station · Coal · 1,320 MW · Illinois
• Joliet 9 Generating Station · Coal · 360.4 MW · Illinois
• IKEA Joliet Rooftop PV System · Solar · 2 MW · Illinois
• Elwood Energy LLC · Gas · 1,344 MW · Illinois

Location

Coordinates 41.4931, -88.1153 from WRI Global Power Plant Database (CC BY 4.0). View on OpenStreetMap.

Frequently asked questions