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Kleen Energy Systems

Natural gas power plant · Middlesex County, Connecticut

Nameplate capacity
693 MW
Rank in Connecticut
#5
of 184 plants
In service since
2011
July 2011

Details

Primary fuel
Natural gas
Technology
Natural Gas Fired Combined Cycle
Operator
Kleen Energy Systems, LLC
County
Middlesex County
Generating units
3
Share of state capacity
6.30%
Rank among natural gas plants in Connecticut
#3 of 47
EIA plant code
56798

Generating units

Individual generating units at Kleen Energy Systems
UnitTechnologyNameplateSummerOnlineStatus
STNatural Gas Fired Combined Cycle295 MW268 MW2011Operating
U1Natural Gas Fired Combined Cycle199 MW177 MW2011Operating
U2Natural Gas Fired Combined Cycle199 MW177 MW2011Operating

Nameplate is the maximum rated output; summer capacity is what the unit can reliably deliver on a hot day, which is typically lower.

Similarly sized plants in Connecticut

Lake Road Generating PlantNatural gas840 MW
MiddletownOther786 MW
New Haven SteamOther642 MW
Milford Power ProjectNatural gas578 MW

About this data

From EIA’s inventory of operable generators, May 2026 release. Capacity is nameplate — the maximum rated output of the equipment, not what the plant actually generates over a year, which depends on how often it runs. A 693 MW solar plant and a 693 MW nuclear plant have the same entry here and produce very different amounts of electricity.

“In service since” is the earliest in-service date among the units still listed, so a site rebuilt around newer equipment can read as younger than the site itself. All Connecticut power plants · What Connecticut actually generates