# Kleen Energy Systems

ISO-NE asset profile · https://askthegrid.com/assets/facilities/kleen-energy-systems

Kleen Energy Systems, LLC - Middlesex County - ISONE

Kleen Energy Systems is a natural-gas-fired combined-cycle power plant located at 1349 River Road, Middletown, Connecticut (Middlesex County). The plant comprises two Siemens SGT6-5000F combustion turbine generators and one Siemens condensing steam turbine generator, with two Vogt heat-recovery steam generators with duct burners. On February 7, 2010, a natural-gas explosion during construction killed six workers and injured many others, causing significant damage. Repairs proceeded, and the facility entered commercial operation in July 2011. The facility is marketed as 620 MW (FERC nameplate capacity totals 693 MW across three units).

## Metrics

- **Nameplate capacity:** 693 MW — Canonical EIA plant baseline.
- **Registry anchor:** Plant 56798 — plant-56798

## Facts

- **Technology:** Natural Gas Fired Combined Cycle
- **Operator:** Kleen Energy Systems, LLC

## Related parties

- **Owner / operator:** Kleen Energy Systems, LLC — Legal asset owner and permit applicant ([source](http://www.kleenenergyct.com))
- **Owner / asset manager:** ArcLight Capital Partners, LLC — Ultimate owner; funds managed by ([source](https://arclight.com))
- **Operator / O&M provider:** Alpha Generation Services, LLC (AlphaGen) — Manager and operator ([source](https://www.alphagen.com))
- **O&M provider / equipment supplier:** Siemens Energy, LLC — Turbine supplier and major maintenance service provider ([source](https://www.siemens-energy.com))
- **Equipment supplier:** Vogt Power International — HRSG and control equipment supplier ([source](https://www.vogtpower.com))
- **Former owner:** Ares Management, LLC — Former majority owner
- **Former owner:** Energy Investors Fund — Early investor
- **Investor / equity investor:** Kyushu Electric Power Co., Inc. — Equity investor and owner
- **Former owner / investor / equity investor:** Sojitz Corporation — Equity investor and former owner
- **Former owner / investor / equity investor:** Osaka Gas Co., Ltd. — Equity investor and former owner
- **Investor / equity investor:** Chugoku Electric Power Co., Inc. — Equity investor and owner
- **Regulator / regulatory counterparty:** Connecticut Siting Council — State regulatory authority ([source](https://portal.ct.gov/csc))

## Sources

- [hartfordbusiness.com](http://hartfordbusiness.com/article/new-ownership-for-middletown-power-plant) — hartfordbusiness.com · public_source — Source retained for exact-record publication review.
- [cga.ct.gov](https://cga.ct.gov/2010/rpt/2010-R-0092.htm) — cga.ct.gov · authoritative — Source retained for exact-record publication review.
- [mbrweb.ferc.gov](https://mbrweb.ferc.gov/SearchMBRAssetAppendix/AssetAppendixDetails?AssetAppendixId=11646) — mbrweb.ferc.gov · authoritative — Source retained for exact-record publication review.
- [mbrweb.ferc.gov](https://mbrweb.ferc.gov/SearchlkpEIA/Index?page=342) — mbrweb.ferc.gov · authoritative — Source retained for exact-record publication review.
- [portal.ct.gov](https://portal.ct.gov/-/media/csc/1_dockets-medialibrary/media_do200_299/docket_225c/do225_225atod_pe1549companychangesackltr20250429_a.pdf?rev=bd11b8b9669a4b6f990f072d33646d3f&hash=EC1EF99E77717FEEA842DF55F998F33B) — portal.ct.gov · authoritative — Source retained for exact-record publication review.
- [portal.ct.gov](https://portal.ct.gov/-/media/deep/air/permits/titlev/kleen_energy/p104-0131.pdf?rev=e526de42d61846d3b892bce074671966&hash=2DCD51FC9D0401E0748B5799963F3625) — portal.ct.gov · authoritative — Source retained for exact-record publication review.

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Canonical page: https://askthegrid.com/assets/facilities/kleen-energy-systems
Website: [Kleen Energy Systems, LLC](http://www.kleenenergyct.com)

Source: Ask the Grid — https://askthegrid.com/