Mystic Generating Station

Mystic Generating Station is a major fossil fuel-fired power station located on the Mystic River in Massachusetts. Owned by Exelon Generation, it is a critical source of electricity for the New England power grid, particularly serving the Greater Boston area. The facility has a long operational history marked by significant technological evolution and increasing environmental scrutiny.

History

The site's history dates to the early 20th century, with the original Boston Edison Company plant beginning operations in the 1940s. Major expansion occurred in the 1960s and 1970s with the construction of larger, more efficient units. The station's ownership transferred through utility deregulation, eventually becoming part of Exelon following its acquisition of Constellation Energy. In 2014, the older, oil-fired Units 4-7 were permanently retired as part of a settlement with the U.S. Environmental Protection Agency and the Conservation Law Foundation.

Description and operations

The currently operational portion consists of two combined-cycle gas turbine units, designated **Unit 8** and **Unit 9**. These units primarily burn liquefied natural gas (LNG) delivered via the adjacent Distrigas terminal, with ultra-low-sulfur diesel as a backup fuel. With a combined capacity of 1,413 megawatts, the plant utilizes heat recovery steam generators to maximize efficiency. The facility is a key participant in the ISO New England wholesale electricity market, often providing essential grid reliability during periods of high demand, such as winter cold snaps.

Environmental impact and regulations

Operations have been subject to extensive regulation under the Clean Air Act and oversight by the Massachusetts Department of Environmental Protection. The retirement of the older units significantly reduced emissions of sulfur dioxide, nitrogen oxides, and particulate matter. Ongoing operations are governed by stringent air quality permits, and the plant utilizes selective catalytic reduction technology to control emissions. Its location in an environmental justice community has drawn attention from advocacy groups like the Mystic River Watershed Association.

Future and decommissioning

In 2021, Exelon announced plans to retire the station by June 2024, citing unfavorable market conditions in the ISO New England capacity market. This decision prompted concerns from grid operators about regional energy security, leading to a reliability-must-run contract extension for Unit 9 through mid-2024. The future of the prime waterfront site, including its LNG import infrastructure, is a subject of discussion among city planners, community groups, and state agencies. Full decommissioning and site remediation will follow the cessation of operations.

See also

* Brayton Point Power Station * Salem Harbor Power Plant * Energy policy of Massachusetts * List of power stations in Massachusetts

Category:Power stations in Massachusetts Category:Buildings and structures in Everett, Massachusetts Category:Buildings and structures in Charlestown, Boston