# Mystic Generating Station

ISO-NE asset profile · https://askthegrid.com/assets/facilities/mystic-generating-station

Constellation Mystic Power LLC - Middlesex County - ISONE

Mystic Generating Station Units 8 and 9 (EIA plant 1588) is a retired natural-gas-fired combined-cycle facility in Middlesex County, Massachusetts, near Boston. The asset comprised two combined-cycle units with a total capacity of 1,744.4 MW, consisting of four Mitsubishi M501G gas turbines (278.6 MW each) and two tandem-compound steam turbines (315 MW each). Uniquely among U.S. natural-gas generators, Mystic 8 and 9 were directly connected to the adjacent Everett LNG import regasification facility, which supplied 100% of their natural gas. The units operated as merchant generators and later as intermediate-duty resources. Originally scheduled to retire in May 2022, they were retained through a two-year ISO New England cost-of-service agreement to maintain fuel security and grid reliability for the Boston metropolitan area. Both units were retired on May 31, 2024, after 21 years of service. The separate Mystic Units 1–7 site, which operated older oil-fired steam turbines and a peaking unit, is a distinct asset not included in this record.

## Metrics

- **Nameplate capacity:** 1744.4 MW — Canonical EIA plant baseline.
- **Registry anchor:** Plant 1588 — plant-1588

## Facts

- **Technology:** Natural Gas Fired Combined Cycle
- **Operator:** Constellation Mystic Power LLC

## Related parties

- **Balancing authority / market operator / regulator:** ISO New England Inc. — ISO/RTO and cost-of-service counterparty ([source](https://www.iso-ne.com/))
- **Former owner:** EBG Holdings LLC — Interim owner following lender acquisition
- **Equipment supplier:** Mitsubishi Heavy Industries, Ltd. (Mitsubishi Power) — Gas-turbine, steam-turbine, and generator OEM

## Sources

- [mhi.com](http://mhi.com/technology/review/sites/g/files/jwhtju2326/files/tr/pdf/e415/e415258.pdf) — mhi.com · public_source — Source retained for exact-record publication review.
- [mbrweb.ferc.gov](https://mbrweb.ferc.gov/SearchlkpEIA/Index?page=270) — mbrweb.ferc.gov · authoritative — Source retained for exact-record publication review.
- [concordnh.gov](https://www.concordnh.gov/Archive.aspx?ADID=3112) — concordnh.gov · authoritative — Source retained for exact-record publication review.
- [constellationenergy.com](https://www.constellationenergy.com/about/locations/mystic-generating-station.html) — constellationenergy.com · public_source — Source retained for exact-record publication review.

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Canonical page: https://askthegrid.com/assets/facilities/mystic-generating-station
Website: [Constellation Mystic Power LLC](https://www.constellationenergy.com/about/locations/mystic-generating-station.html)

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