# Perryman

PJM Natural Gas Fired Combustion Turbine, Petroleum Liquids · https://askthegrid.com/assets/facilities/perryman

Perryman is a natural gas-fired power facility with 492.3 MW of EIA-reported nameplate capacity in Harford County, Maryland, registered as EIA Plant ID 1556. Constellation Power Source Generation, LLC owns and operates the plant. Its 2014–2015 Unit 6 expansion used two dual-fuel Pratt & Whitney FT4000 turbines connected to one generator; the mechanical contractor described the arrangement as a first-of-its-kind Pratt & Whitney design for that size range.
PERRYMAN13 KVCT 1; PERRYMAN13 KVCT 4; PERRYMAN33 KVCT 51; PERRYMN613.8 KV PERYMAN6 · 115 kV · Baltimore Gas & Electric Co (BGE).

## Key facts

- Technology: Natural Gas Fired Combustion Turbine, Petroleum Liquids
- Power capacity: 492.3 MW
- Operating status: operating

## Grid and market context

- ISO/RTO: PJM
- Balancing authority: PJM Interconnection, LLC (PJM)

## Source-backed facts

- Owner logo domain: constellationenergy.com — Perryman Generating Station | Constellation Energy Locations · confidence: medium
- Description: Perryman is an operating gas-and-oil generating plant in Harford County, Maryland, with five operating generators totaling 492.3 MW of nameplate capacity. The plant operates in the PJM market and is reported as operated by Constellation Power Source Generation, LLC; its first unit entered service in January 1972. Constellation identifies the facility at 900 Chelsea Road in Aberdeen and describes it as a dual-fuel plant with oil-fired combustion turbines and a natural-gas unit. — Perryman Generating Station | Constellation Energy Locations · confidence: medium
- Identifiers.7: {"value":"PERRYMAN 6","system":"PJM capacity-market resource"} — Source · confidence: high
- Identifiers.8: {"value":"PERRYMAN CT 1","system":"PJM capacity-market resource"} — Source · confidence: high
- Identifiers.9: {"value":"PERRYMAN CT 3","system":"PJM capacity-market resource"} — Source · confidence: high
- Identifiers.10: {"value":"PERRYMAN CT 4","system":"PJM capacity-market resource"} — Source · confidence: high
- Identifiers.11: {"value":"PERRYMAN CT 51","system":"PJM capacity-market resource"} — Source · confidence: medium
- Parties.1: {"relationship":"Public owner/operator brand","name":"Constellation Energy","official_url":"https://www.constellationenergy.com/"} — Perryman Generating Station | Constellation Energy Locations · confidence: high
- Unit configuration: Five operating combustion-turbine units: four oil-fueled units and one natural-gas-fueled unit, with dual-fuel gas/oil capability. — Perryman Generating Station | Constellation Energy Locations · confidence: medium
- Unit count: 5 — Perryman Generating Station | Constellation Energy Locations · confidence: medium
- Construction scope: The documented 120-MW Perryman expansion installed two dual-fuel Pratt & Whitney FT4000 turbines in simple-cycle configuration, rated at 60 MW each, with one shared generator, a 2-into-1 stack and SCR, balance-of-plant equipment, and mechanical piping. The Maryland permit identifies three identical Westinghouse model 501 simple-cycle combustion turbines burning distillate oil. Maryland DNR describes the broader facility as having six physical simple-cycle combustion turbines—three oil-fired and three natural-gas-fired—which reflects the two-turbine FT4000 block. — Constellation Perryman 2024 IssuedT5 Permit · confidence: medium
- Construction scope: The documented 120-MW Perryman expansion installed two dual-fuel Pratt & Whitney FT4000 turbines in simple-cycle configuration, rated at 60 MW each, with one shared generator, a 2-into-1 stack and SCR, balance-of-plant equipment, and mechanical piping. The Maryland permit identifies three identical Westinghouse model 501 simple-cycle combustion turbines burning distillate oil. Maryland DNR describes the broader facility as having six physical simple-cycle combustion turbines—three oil-fired and three natural-gas-fired—which reflects the two-turbine FT4000 block. — 9677 Perryman Reliability Modification fact sheet · confidence: medium
- Product url: https://app.prattwhitney.com/2012-02-09-FT4000-SWIFTPAC-Featured-in-Cogeneration-On-Site-Power-Production — FT4000 SWIFTPAC Featured in Cogeneration & On-Site Power Production · confidence: high
- Kind: thermal — Perryman Generating Station | Constellation Energy Locations · confidence: high
- Kind: thermal — 9677 Perryman Reliability Modification fact sheet · confidence: high
- Equipment models.1: {"manufacturer_domain":"prattwhitney.com","product_url":"https://app.prattwhitney.com/2012-02-09-FT4000-SWIFTPAC-Featured-in-Cogeneration-On-Site-Power-Production","count":2,"unit_mw":60,"name":"Pratt & Whitney FT4000 SWIFTPAC"} — Projects - Frank Lill and Son, Victor, NY · confidence: high
- Description: Perryman is a five-generator, dual-fuel gas-and-oil generating station in Aberdeen, Harford County, Maryland, operated by Constellation Power Source Generation, LLC. Four units are oil-fueled combustion turbines, while the gas-capable fifth unit was added in 1995. The station's original units entered service in 1972, and Exelon Generation added the 120 MW Perryman 6 expansion, which began commercial operation on June 28, 2015. Ownership transitioned from the Constellation corporate group into Exelon's generation business through the March 2012 merger and back into the independent Constellation generation business through Exelon's February 2022 separation; no separate project sale was identified. — Perryman Generating Station | Constellation Energy Locations · confidence: medium
- Description: Perryman is a five-generator, dual-fuel gas-and-oil generating station in Aberdeen, Harford County, Maryland, operated by Constellation Power Source Generation, LLC. Four units are oil-fueled combustion turbines, while the gas-capable fifth unit was added in 1995. The station's original units entered service in 1972, and Exelon Generation added the 120 MW Perryman 6 expansion, which began commercial operation on June 28, 2015. Ownership transitioned from the Constellation corporate group into Exelon's generation business through the March 2012 merger and back into the independent Constellation generation business through Exelon's February 2022 separation; no separate project sale was identified. — Exelon Generation's New Maryland Natural Gas Power Plant Now Operational · confidence: medium
- Quality notes: ["Reported capacity depends on the metric and reporting snapshot: Constellation's location page describes a 404 MW facility, the 2015 Perryman 6 announcement reported 475 MW of full generating capacity after the expansion, and the EIA-based directory reports 492.3 MW of nameplate capacity. These figures should not be treated as interchangeable.","The current five-generator configuration is consistent with the documented February 1, 2016 deactivation of Perryman Unit CT 2; The documented 2012 and 2022 ownership changes were corporate transactions rather than separately priced Perryman asset sales.","The Unit 6 expansion is described as a 120 MW project using two turbines and one generator, while the EIA-based generator record reports GT6 at 141 MW nameplate capacity; these are different project and rating descriptions."] — Perryman Generating Station | Constellation Energy Locations · confidence: medium
- Quality notes: ["Reported capacity depends on the metric and reporting snapshot: Constellation's location page describes a 404 MW facility, the 2015 Perryman 6 announcement reported 475 MW of full generating capacity after the expansion, and the EIA-based directory reports 492.3 MW of nameplate capacity. These figures should not be treated as interchangeable.","The current five-generator configuration is consistent with the documented February 1, 2016 deactivation of Perryman Unit CT 2; The documented 2012 and 2022 ownership changes were corporate transactions rather than separately priced Perryman asset sales.","The Unit 6 expansion is described as a 120 MW project using two turbines and one generator, while the EIA-based generator record reports GT6 at 141 MW nameplate capacity; these are different project and rating descriptions."] — Exelon Generation's New Maryland Natural Gas Power Plant Now Operational · confidence: medium
- Quality notes: ["Reported capacity depends on the metric and reporting snapshot: Constellation's location page describes a 404 MW facility, the 2015 Perryman 6 announcement reported 475 MW of full generating capacity after the expansion, and the EIA-based directory reports 492.3 MW of nameplate capacity. These figures should not be treated as interchangeable.","The current five-generator configuration is consistent with the documented February 1, 2016 deactivation of Perryman Unit CT 2; The documented 2012 and 2022 ownership changes were corporate transactions rather than separately priced Perryman asset sales.","The Unit 6 expansion is described as a 120 MW project using two turbines and one generator, while the EIA-based generator record reports GT6 at 141 MW nameplate capacity; these are different project and rating descriptions."] — Constellation Power Source Generation, LLC, Docket Nos.... · confidence: medium
- Quality notes: ["Reported capacity depends on the metric and reporting snapshot: Constellation's location page describes a 404 MW facility, the 2015 Perryman 6 announcement reported 475 MW of full generating capacity after the expansion, and the EIA-based directory reports 492.3 MW of nameplate capacity. These figures should not be treated as interchangeable.","The current five-generator configuration is consistent with the documented February 1, 2016 deactivation of Perryman Unit CT 2; The documented 2012 and 2022 ownership changes were corporate transactions rather than separately priced Perryman asset sales.","The Unit 6 expansion is described as a 120 MW project using two turbines and one generator, while the EIA-based generator record reports GT6 at 141 MW nameplate capacity; these are different project and rating descriptions."] — Source · confidence: medium
- Financing summary: No plant-specific project financing, acquisition financing, debt facility, lender, acquisition price, or sale consideration was disclosed. Perryman 6 was described as a merchant natural-gas plant constructed pursuant to Exelon's Maryland merger commitment. An SEC filing reported $24 million of capital expenditures and $6 million of development costs as of December 31, 2013 for pursuit of Maryland generation commitments overall, but did not allocate those amounts specifically to Perryman 6. — FINANCIAL ARRANGEMENTS BEHIND NEW GENERATING CAPACITY · confidence: medium
- Financing summary: No plant-specific project financing, acquisition financing, debt facility, lender, acquisition price, or sale consideration was disclosed. Perryman 6 was described as a merchant natural-gas plant constructed pursuant to Exelon's Maryland merger commitment. An SEC filing reported $24 million of capital expenditures and $6 million of development costs as of December 31, 2013 for pursuit of Maryland generation commitments overall, but did not allocate those amounts specifically to Perryman 6. — Source · confidence: medium
- Timeline.4: {"event":"EPC contract for Unit 6 expansion","date":"2013-07-26","detail":"Exelon's Generation business executed an engineering, procurement and construction contract to expand the Perryman site with 120 MW of new natural-gas-fired generation, with commercial operation expected in 2015."} — Source · confidence: high
- Timeline.6: {"event":"Commercial operation — Perryman 6","date":"2015-06-28","detail":"Exelon Generation announced that the 120 MW Perryman 6 natural-gas generating unit began commercial operation on June 28, 2015."} — Exelon Generation's New Maryland Natural Gas Power Plant Now Operational · confidence: high
- Timeline.7: {"event":"Deactivation — Perryman Unit CT 2","date":"2016-02-01","detail":"Perryman Unit CT 2, reported at approximately 51 MW, was deactivated effective February 1, 2016."} — Constellation Power Source Generation, LLC, Docket Nos.... · confidence: high
- Quality notes.0: Reported capacity depends on the metric and reporting snapshot: Constellation's location page describes a 404 MW facility, the 2015 Perryman 6 announcement reported 475 MW of full generating capacity after the expansion, and the EIA-based directory reports 492.3 MW of nameplate capacity. These figures should not be treated as interchangeable. — Perryman Generating Station | Constellation Energy Locations · confidence: high
- Quality notes.0: Reported capacity depends on the metric and reporting snapshot: Constellation's location page describes a 404 MW facility, the 2015 Perryman 6 announcement reported 475 MW of full generating capacity after the expansion, and the EIA-based directory reports 492.3 MW of nameplate capacity. These figures should not be treated as interchangeable. — Exelon Generation's New Maryland Natural Gas Power Plant Now Operational · confidence: high
- Quality notes.1: The current five-generator configuration is consistent with the documented February 1, 2016 deactivation of Perryman Unit CT 2; generator counts should not be inferred from capacity totals. — Constellation Power Source Generation, LLC, Docket Nos.... · confidence: high
- Quality notes.2: The documented 2012 and 2022 ownership changes were corporate transactions rather than separately priced Perryman asset sales. — FINANCIAL ARRANGEMENTS BEHIND NEW GENERATING CAPACITY · confidence: medium
- Quality notes.2: The documented 2012 and 2022 ownership changes were corporate transactions rather than separately priced Perryman asset sales. — Source · confidence: medium
- Commercial parties.1: {"relationship":"Current public owner/operator brand","name":"Constellation Energy","detail":"Constellation identifies Perryman as owned and operated by Constellation and describes the facility as a five-unit peaking station in Aberdeen.","official_url":"https://www.constellationenergy.com/"} — Perryman Generating Station | Constellation Energy Locations · confidence: high
- Commercial parties.6: {"relationship":"Combustion-turbine OEM","name":"Pratt & Whitney","detail":"The Unit 6 expansion used two dual-fuel Pratt & Whitney FT4000 turbines in simple-cycle configuration.","official_url":"https://www.prattwhitney.com/"} — Exelon Generation's New Maryland Natural Gas Power Plant Now Operational · confidence: high
- Acquisition detail: On 2012-03-12, Exelon completed its merger with Constellation Energy Group. Constellation became a wholly owned subsidiary of Exelon, and Perryman was subsequently operated within Exelon Generation. This was a corporate-parent transaction, not a documented sale of the Perryman plant itself. — Exelon Generation's New Maryland Natural Gas Power Plant Now Operational · confidence: medium
- Interconnection voltage kv: 115 — Harford to Perryman - BGE · confidence: medium
- Grid role: Peaking and flexible generation used to provide power during periods of high demand. — Perryman Generating Station | Constellation Energy Locations · confidence: high

## Timeline

- 2012-03-12 — Corporate acquisition and ownership transition
  Exelon and Constellation Energy completed their merger effective March 12, 2012. Exelon's SEC filing states that generation subsidiaries acquired from Constellation were contributed to Exelon's Generation business; this is the documented predecessor-owner transition for Perryman, not a separately priced plant sale.
  Source: Source (https://www.sec.gov/Archives/edgar/data/1109357/000119312514051838/R12.htm)
- 2013-07-26 — EPC contract for Unit 6 expansion
  Exelon's Generation business executed an engineering, procurement and construction contract to expand the Perryman site with 120 MW of new natural-gas-fired generation, with commercial operation expected in 2015.
  Source: Source (https://www.sec.gov/Archives/edgar/data/1109357/000119312514051838/R12.htm)
- 2015-06-28 — Commercial operation — Perryman 6
  Exelon Generation announced that the 120 MW Perryman 6 natural-gas generating unit began commercial operation on June 28, 2015.
  Source: Exelon Generation's New Maryland Natural Gas Power Plant Now Operational (https://www.prnewswire.com/news-releases/exelon-generations-new-maryland-natural-gas-power-plant-now-operational-300106253.html)
- 2022-02-02 — Corporate separation into independent Constellation
  Exelon completed the separation of Constellation Energy, described by Exelon as its former power-generation and competitive-energy business. The transaction was a corporate separation and not a disclosed Perryman-specific asset sale.
  Source: Exelon Completes Separation of Constellation, Moving Forward as Nation’s Premier Transmission and Distribution Utility Company (https://www.exeloncorp.com/newsroom/exelon-completes-separation-of-constellation)
- 2025-03-18 — Withdrawal of Perryman 6 deactivation notice
  Constellation withdrew the Perryman 6 deactivation notice and stated that the unit would be capable of returning to operation no later than the fourth quarter of 2025; the filing stated that Perryman 3 would continue operating.
  Source: March 18, 2025 Mr. Michael Bryson Senior Vice President, Operations PJM Interconnection, LLC PO Box 1525 Southeastern, PA 19399-1525 Via (https://www.pjm.com/-/media/DotCom/planning/gen-retire/deactivation-notices/perryman-6-unit-1-deactivation-withdrawal.pdf)

## Sources

- [Perryman Generating Station | Constellation Energy Locations](https://www.constellationenergy.com/about/locations/perryman-generating-station.html) — constellationenergy.com · tier other
- [https://www.pjm.com/-/media/DotCom/etools/capacity...](https://www.pjm.com/-/media/DotCom/etools/capacity-exchange/erpm-designated.csv) — pjm.com · tier other
- [Constellation Perryman 2024 IssuedT5 Permit](https://mde.maryland.gov/programs/permits/AirManagementPermits/Test/Constellation%20Perryman%202024%20IssuedT5%20Permit.pdf) — mde.maryland.gov · tier regulatory
- [March 18, 2025 Mr. Michael Bryson Senior Vice President, Operations PJM Interconnection, LLC PO Box 1525 Southeastern, PA 19399-1525 Via](https://www.pjm.com/-/media/DotCom/planning/gen-retire/deactivation-notices/perryman-6-unit-1-deactivation-withdrawal.pdf) — pjm.com · tier other
- [Innovative Angles](https://www.franklillandson.com/app-projects/perryman-generating-station) — franklillandson.com · tier other
- [9677 Perryman Reliability Modification fact sheet](https://dnr.maryland.gov/pprp/Documents/9677-Perryman-Reliability-Modification-factsheet.pdf) — dnr.maryland.gov · tier regulatory
- [FT4000 SWIFTPAC Featured in Cogeneration & On-Site Power Production](https://app.prattwhitney.com/2012-02-09-FT4000-SWIFTPAC-Featured-in-Cogeneration-On-Site-Power-Production) — app.prattwhitney.com · tier other
- [Projects - Frank Lill and Son, Victor, NY](https://www.franklillandson.com/projects?page=2&prop_ModuleId=2137) — franklillandson.com · tier other
- [Exelon Generation's New Maryland Natural Gas Power Plant Now Operational](https://www.prnewswire.com/news-releases/exelon-generations-new-maryland-natural-gas-power-plant-now-operational-300106253.html) — prnewswire.com · tier other
- [Constellation Power Source Generation, LLC, Docket Nos. ...](https://www.ferc.gov/sites/default/files/2020-05/E-6_75.pdf) — ferc.gov · tier regulatory
- [Source](https://www.sec.gov/Archives/edgar/data/1109357/000119312514051838/R12.htm) — sec.gov · tier regulatory
- [FINANCIAL ARRANGEMENTS BEHIND NEW GENERATING CAPACITY](https://www.publicpower.org/system/files/documents/Financial_Arrangements_Behind_New_Generating_Capacity_2018_1.pdf) — publicpower.org · tier other
- [Exelon Completes Separation of Constellation, Moving Forward as Nation’s Premier Transmission and Distribution Utility Company](https://www.exeloncorp.com/newsroom/exelon-completes-separation-of-constellation) — exeloncorp.com · tier other
- [Harford to Perryman - BGE](https://www.bge-tsrep.com/projects/harford-to-perryman-115-kv-line-rebuild/) — bge-tsrep.com · tier other

## Data quality

- Reported capacity depends on the metric and reporting snapshot: Constellation's location page describes a 404 MW facility, the 2015 Perryman 6 announcement reported 475 MW of full generating capacity after the expansion, and the EIA-based directory reports 492.3 MW of nameplate capacity. These figures should not be treated as interchangeable. The current five-generator configuration is consistent with the documented February 1, 2016 deactivation of Perryman Unit CT 2; generator counts should not be inferred from capacity totals. The documented 2012 and 2022 ownership changes were corporate transactions rather than separately priced Perryman asset sales. The Unit 6 expansion is described as a 120 MW project using two turbines and one generator, while the EIA-based generator record reports GT6 at 141 MW nameplate capacity; these are different project and rating descriptions.

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