# Zion Energy Center

PJM Natural Gas Fired Combustion Turbine · https://askthegrid.com/assets/facilities/zion-energy-center

Zion Energy Center is a natural gas-fired power facility with 596.7 MW of EIA-reported nameplate capacity in Lake County, Illinois, registered as EIA Plant ID 55392. Zion Energy LLC owns and operates the plant. It operates in the PJM market as a dual-fuel peaking facility.

## Key facts

- Technology: Natural Gas Fired Combustion Turbine
- Power capacity: 596.7 MW
- Operating status: operating

## Grid and market context

- ISO/RTO: PJM
- Balancing authority: PJM Interconnection, LLC (PJM)
- Substation: Zion Energy Center Substation
- Point of interconnection: Zion Energy Center Substation
- Transmission owner: Commonwealth Edison (ComEd)
- Interconnection voltage: 345 kV

## Source-backed facts

- Owner logo domain: constellationenergy.com — Constellation Completes Calpine Transaction, Powering America's Clean Energy Future · confidence: medium
- Identifiers: [{"value":"55392","system":"EIA plant ID"},{"value":"CTG1","system":"EIA generator ID"},{"value":"CTG2","system":"EIA generator ID"},{"value":"CTG3","system":"EIA generator ID"},{"value":"PJM","system":"ISO/RTO"},{"value":"02-1319-000","system":"FERC EWG docket"},{"value":"ER02-1319-000","system":"FERC tariff docket"},{"value":"Y2-103","system":"PJM interconnection queue"},{"value":"Y3-013","system":"PJM interconnection queue"},{"value":"ZION 1","system":"PJM market resource"},{"value":"ZION 2","system":"PJM market resource"},{"value":"ZION 3","system":"PJM market resource"}] — eLibrary | Document Information · confidence: medium
- Identifiers: [{"value":"55392","system":"EIA plant ID"},{"value":"CTG1","system":"EIA generator ID"},{"value":"CTG2","system":"EIA generator ID"},{"value":"CTG3","system":"EIA generator ID"},{"value":"PJM","system":"ISO/RTO"},{"value":"02-1319-000","system":"FERC EWG docket"},{"value":"ER02-1319-000","system":"FERC tariff docket"},{"value":"Y2-103","system":"PJM interconnection queue"},{"value":"Y3-013","system":"PJM interconnection queue"},{"value":"ZION 1","system":"PJM market resource"},{"value":"ZION 2","system":"PJM market resource"},{"value":"ZION 3","system":"PJM market resource"}] — PJM evaluates expansion of gas-fired Zion Energy Center in Illinois · confidence: medium
- Identifiers: [{"value":"55392","system":"EIA plant ID"},{"value":"CTG1","system":"EIA generator ID"},{"value":"CTG2","system":"EIA generator ID"},{"value":"CTG3","system":"EIA generator ID"},{"value":"PJM","system":"ISO/RTO"},{"value":"02-1319-000","system":"FERC EWG docket"},{"value":"ER02-1319-000","system":"FERC tariff docket"},{"value":"Y2-103","system":"PJM interconnection queue"},{"value":"Y3-013","system":"PJM interconnection queue"},{"value":"ZION 1","system":"PJM market resource"},{"value":"ZION 2","system":"PJM market resource"},{"value":"ZION 3","system":"PJM market resource"}] — Sheet1 · confidence: medium
- Description: Zion Energy Center is a 596.7 MW natural-gas-fired power plant in Zion, Lake County, Illinois. The plant began operation in June 2002 and consists of three operating combustion-turbine generators, CTG1 through CTG3, each with 198.9 MW of nameplate capacity. The facility is a dual-fuel peaking plant capable of using natural gas or distillate fuel oil and is located within the PJM market. — Power plant profile: Zion Energy Center, US · confidence: medium
- Parties.1: {"relationship":"Current parent owner","name":"Constellation Energy Corporation","official_url":"https://www.constellationenergy.com"} — Constellation Completes Calpine Transaction, Powering America's Clean Energy Future · confidence: medium
- Parties.2: {"relationship":"Original developer and former parent owner","name":"Calpine Corporation","official_url":"https://www.calpine.com"} — PJM evaluates expansion of gas-fired Zion Energy Center in Illinois · confidence: medium
- Parties.3: {"relationship":"Gas-turbine and electric-generator OEM","name":"GE Power Systems","official_url":"https://www.gevernova.com/gas-power"} — Power plant profile: Zion Energy Center, US · confidence: medium
- Parties.6: {"relationship":"Power offtaker","name":"Alliant Energy","official_url":"https://www.alliantenergy.com"} — Power plant profile: Zion Energy Center, US · confidence: medium
- Parties.7: {"relationship":"Power offtaker","name":"We Energies","official_url":"https://www.we-energies.com"} — Power plant profile: Zion Energy Center, US · confidence: medium
- Site acres: 114 — Source · confidence: medium
- Product url: https://www.gevernova.com/gas-power/products/gas-turbines/7f — 7F Heavy Duty Gas Turbine | 7F.04/7F.05 | GE Vernova · confidence: medium
- Manufacturer domain: gevernova.com — 7F Heavy Duty Gas Turbine | 7F.04/7F.05 | GE Vernova · confidence: medium
- Equipment models: [{"manufacturer_domain":"gevernova.com","product_url":"https://www.gevernova.com/gas-power/products/gas-turbines/7f","count":3,"unit_mw":198.9,"name":"MS7001FA / PG7241 (FA) gas turbine"}] — 7F Heavy Duty Gas Turbine | 7F.04/7F.05 | GE Vernova · confidence: medium
- Product family: MS7001FA / PG7241 (FA) — 7F Heavy Duty Gas Turbine | 7F.04/7F.05 | GE Vernova · confidence: medium
- Equipment models.0: {"manufacturer_domain":"gevernova.com","product_url":"https://www.gevernova.com/gas-power/products/gas-turbines/7f","count":3,"unit_mw":198.9,"name":"MS7001FA / PG7241 (FA) gas turbine"} — 7F Heavy Duty Gas Turbine | 7F.04/7F.05 | GE Vernova · confidence: medium
- Description: Zion Energy Center is a 596.7 MW natural-gas-fired simple-cycle peaking facility in Zion, Lake County, Illinois, with three operating combustion-turbine generators and distillate fuel oil as an alternate fuel. Zion Energy LLC owns and operates the facility; its parent ownership transitioned from Calpine to Constellation through parent-level transactions rather than a separately disclosed project sale. Calpine began construction in August 2001, and plant records identify initial operation in June 2002. A further 160 MW simple-cycle unit entered commercial operation in June 2003, with GE Power Systems equipment and Kenny Construction Company as general contractor. — Source · confidence: medium
- Quality notes: ["The disclosed 2018 and 2026 transaction values relate to parent-level Calpine acquisitions, not a separately priced Zion Energy Center sale consideration.","Historical capacity reports differ: Calpine reported 495 MW during development, the 2003 addition report described 480 MW, a 2006 filing reported 546 MW, and current EIA-derived data reports 596.7 MW; these appear to be different reporting snapshots of the same facility.","A 2015 PJM study evaluated a proposed 90 MW turbine uprate and 3x1 combined-cycle configuration, but the cited material does not establish that the proposal was completed. Current plant data continues to describe an operating three-generator combustion-turbine facility.","No retirement date or completed repowering event is identified; the facility is reported as operating as of the current data record."] — Source · confidence: medium
- Quality notes: ["The disclosed 2018 and 2026 transaction values relate to parent-level Calpine acquisitions, not a separately priced Zion Energy Center sale consideration.","Historical capacity reports differ: Calpine reported 495 MW during development, the 2003 addition report described 480 MW, a 2006 filing reported 546 MW, and current EIA-derived data reports 596.7 MW; these appear to be different reporting snapshots of the same facility.","A 2015 PJM study evaluated a proposed 90 MW turbine uprate and 3x1 combined-cycle configuration, but the cited material does not establish that the proposal was completed. Current plant data continues to describe an operating three-generator combustion-turbine facility.","No retirement date or completed repowering event is identified; the facility is reported as operating as of the current data record."] — PJM evaluates expansion of gas-fired Zion Energy Center in... · confidence: medium
- Timeline.2: {"event":"Construction began","date":"2001-08","detail":"Calpine's SEC filing described Zion as a 495 MW simple-cycle facility and stated that construction began in August 2001."} — Source · confidence: high
- Timeline.5: {"event":"PJM uprate and combined-cycle proposal studied","date":"2015-05-20","detail":"PJM studied Zion's request to uprate its three combustion turbines by 30 MW each, or 90 MW total, as a 3x1 combined-cycle facility under queue project Y3-013. The cited study does not establish completion of the proposed uprate or repowering."} — PJM evaluates expansion of gas-fired Zion Energy Center in... · confidence: medium
- Timeline.8: {"event":"Constellation completed Calpine acquisition","date":"2026-01-07","detail":"Constellation announced completion of its acquisition of Calpine from Energy Capital Partners. The transaction transferred Calpine's generation portfolio, including the parent-level ownership chain associated with Zion Energy LLC, to Constellation."} — Constellation Completes Calpine Transaction, Powering America's Clean Energy Future · confidence: medium
- Commercial parties.1: {"relationship":"Current parent owner","name":"Constellation Energy Corporation","detail":"Current parent of the Calpine generation portfolio after completing the Calpine acquisition on January 7, 2026.","official_url":"https://www.constellationenergy.com"} — Constellation Completes Calpine Transaction, Powering America's Clean Energy Future · confidence: medium
- Commercial parties.3: {"relationship":"2018 parent-level acquirer and 2026 seller of Calpine","name":"Energy Capital Partners","detail":"Led the consortium that acquired Calpine in March 2018 and sold Calpine to Constellation in the January 2026 closing.","official_url":"https://www.ecpgp.com"} — Constellation Completes Calpine Transaction, Powering America's Clean Energy Future · confidence: medium
- Commercial parties.9: {"relationship":"Power offtaker","name":"Alliant Energy","detail":"Identified as one of the project's power offtakers.","official_url":"https://www.alliantenergy.com"} — Source · confidence: medium
- Commercial parties.10: {"relationship":"Power offtaker","name":"We Energies","detail":"Identified as one of the project's power offtakers.","official_url":"https://www.we-energies.com"} — Source · confidence: medium
- Quality notes.1: Historical capacity reports differ: Calpine reported 495 MW during development, the 2003 addition report described 480 MW, a 2006 filing reported 546 MW, and current EIA-derived data reports 596.7 MW; these appear to be different reporting snapshots of the same facility. — Source · confidence: high
- Quality notes.1: Historical capacity reports differ: Calpine reported 495 MW during development, the 2003 addition report described 480 MW, a 2006 filing reported 546 MW, and current EIA-derived data reports 596.7 MW; these appear to be different reporting snapshots of the same facility. — Source · confidence: high
- Quality notes.2: A 2015 PJM study evaluated a proposed 90 MW turbine uprate and 3x1 combined-cycle configuration, but the cited material does not establish that the proposal was completed. Current plant data continues to describe an operating three-generator combustion-turbine facility. — PJM evaluates expansion of gas-fired Zion Energy Center in... · confidence: medium
- Interconnection voltage kv: 345 — Source · confidence: high
- Status date: 2026-02-06 — Table of Operating Power Plants and Projects Under Construction as of: Friday, February 6, 2026 · confidence: high
- Status detail: Calpine's operating-plant table dated 2026-02-06 lists Zion Energy Center as an operating RFC/Illinois simple-cycle plant. PJM resource records include ZION 1, ZION 2, and ZION 3 in the COMED zone as dual-fuel gas combustion-turbine resources. No qualifying whole-plant or unit retirement, mothball, standby, or fuel-conversion date is identified in the current records reviewed. — Table of Operating Power Plants and Projects Under Construction as of: Friday, February 6, 2026 · confidence: medium
- Status detail: Calpine's operating-plant table dated 2026-02-06 lists Zion Energy Center as an operating RFC/Illinois simple-cycle plant. PJM resource records include ZION 1, ZION 2, and ZION 3 in the COMED zone as dual-fuel gas combustion-turbine resources. No qualifying whole-plant or unit retirement, mothball, standby, or fuel-conversion date is identified in the current records reviewed. — Zion energy center - Global Energy Monitor · confidence: medium
- Grid role: Simple-cycle peaking generation — Source · confidence: high
- Operating status: operating — Table of Operating Power Plants and Projects Under Construction as of: Friday, February 6, 2026 · confidence: high
- Operating status: operating — Zion energy center - Global Energy Monitor · confidence: high

## Timeline

- 2018-03-08 — Calpine acquired by ECP-led consortium
  An affiliate of Energy Capital Partners and a consortium including Access Industries and Canada Pension Plan Investment Board completed the acquisition of Calpine from its stockholders. Calpine stockholders were to receive $15.25 per share; ECP describes the take-private as a $17 billion transaction that closed in March 2018. This was an indirect parent-level ownership change for Zion, not a separately priced Zion sale.
  Source: Consortium Led by Energy Capital Partners Completes Acquisition of Calpine Corporation; Announces Management Roles and Board of Directors | Energy Capital Partners I ECP (https://www.ecpgp.com/about/news-and-insights/press-releases/2018/consortium-led-by-energy-capital-partners-completes-acquisition-of-calpine-corporation-announces-management-roles-and-board-of-directors)
- 2025-01-10 — Constellation agreed to acquire Calpine
  Constellation announced a cash-and-stock agreement to acquire Calpine at an equity purchase price of approximately $16.4 billion, comprising 50 million Constellation shares and $4.5 billion cash plus assumed Calpine net debt of approximately $12.7 billion.
  Source: Constellation to Acquire Calpine; Creates America’s Leading Producer of Clean and Reliable Energy to Meet Growing Demand for Customers and Communities (https://www.constellationenergy.com/news/2025/constellation-to-acquire-calpine-creates-americas-leading-producer-of-clean-and-reliable-energy-to-meet-growing-demand-for-customers-and-communities.html)

## Sources

- [Constellation Completes Calpine Transaction, Powering America's Clean Energy Future](https://www.constellationenergy.com/news/2026/01/constellation-completes-calpine-transaction-powering-americas-clean-energy-future.html) — constellationenergy.com · tier other
- [Zion energy center - Global Energy Monitor](https://www.gem.wiki/Zion_energy_center) — gem.wiki · tier other
- [eLibrary | Document Information](https://elibrary.ferc.gov/eLibrary/docinfo?accession_Number=20090124-2440&sid=3f2fa233-444b-4e87-a5c4-0277499c4be4) — elibrary.ferc.gov · tier regulatory
- [PJM evaluates expansion of gas-fired Zion Energy Center in ...](https://www.power-eng.com/gas/turbines/pjm-evaluates-expansion-of-gas-fired-zion-energy-center-in-illinois/) — power-eng.com · tier other
- [Sheet1](https://www.pjm.com/-/media/DotCom/markets-ops/rpm/rpm-auction-info/2025-2026/2025-2026-rpm-existing-resource-list-post.xlsx) — pjm.com · tier other
- [Calpine: America's Premier Competitive Power Company](https://www.calpine.com/) — calpine.com · tier other
- [Zion Station (Retired) | Constellation Energy Locations](https://www.constellationenergy.com/about/locations/zion-station.html) — constellationenergy.com · tier other
- [Power plant profile: Zion Energy Center, US](https://www.power-technology.com/data-insights/power-plant-profile-zion-energy-center-us/) — power-technology.com · tier other
- [Source](https://power-eng.com/gas/turbines/pjm-evaluates-expansion-of-gas-fired-zion-energy-center-in-illinois) — power-eng.com · tier other
- [Source](https://power-technology.com/data-insights/power-plant-profile-zion-energy-center-us) — power-technology.com · tier other
- [7F Heavy Duty Gas Turbine | 7F.04/7F.05 | GE Vernova](https://www.gevernova.com/gas-power/products/gas-turbines/7f) — gevernova.com · tier other
- [Source](https://www.sec.gov/Archives/edgar/data/916457/000089161802001569/f80168e10-k.htm) — sec.gov · tier regulatory
- [Source](https://www.sec.gov/Archives/edgar/data/916457/000089161807000155/f27583e10vk.htm) — sec.gov · tier regulatory
- [Consortium Led by Energy Capital Partners Completes Acquisition of Calpine Corporation; Announces Management Roles and Board of Directors | Energy Capital Partners I ECP](https://www.ecpgp.com/about/news-and-insights/press-releases/2018/consortium-led-by-energy-capital-partners-completes-acquisition-of-calpine-corporation-announces-management-roles-and-board-of-directors) — ecpgp.com · tier other
- [Constellation to Acquire Calpine; Creates America’s Leading Producer of Clean and Reliable Energy to Meet Growing Demand for Customers and Communities](https://www.constellationenergy.com/news/2025/constellation-to-acquire-calpine-creates-americas-leading-producer-of-clean-and-reliable-energy-to-meet-growing-demand-for-customers-and-communities.html) — constellationenergy.com · tier other
- [Constellation closes $22B Calpine acquisition | CEG 8-K Filing](https://www.stocktitan.net/sec-filings/CEG/8-k-constellation-energy-corp-reports-material-event-3aa05f50caaa.html) — stocktitan.net · tier other
- [Source](https://www.atcllc.com/oasis/Customer_Notices/ATCNetworkCustomerMeeting052411_Carpenter.pdf) — atcllc.com · tier other
- [Table of Operating Power Plants and Projects Under Construction as of: Friday, February 6, 2026](https://www.calpine.com/wp-content/uploads/2026/02/CPN-PORT-1_Q12026.pdf) — calpine.com · tier other

## Data quality

- The disclosed 2018 and 2026 transaction values relate to parent-level Calpine acquisitions, not a separately priced Zion Energy Center sale consideration. Historical capacity reports differ: Calpine reported 495 MW during development, the 2003 addition report described 480 MW, a 2006 filing reported 546 MW, and current EIA-derived data reports 596.7 MW; these appear to be different reporting snapshots of the same facility. A 2015 PJM study evaluated a proposed 90 MW turbine uprate and 3x1 combined-cycle configuration, but the cited material does not establish that the proposal was completed. Current plant data continues to describe an operating three-generator combustion-turbine facility. No retirement date or completed repowering event is identified; the facility is reported as operating as of the current data record.

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Canonical page: https://askthegrid.com/assets/facilities/zion-energy-center

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