Dynegy said Monday it will close as of June 1 its 1,488-MW coal-fired Brayton Point power plant in Somerset, Massachusetts.
The Houston-based company said the decision to shut Brayton Point was made in 2013, before Dynegy owned the facility.
In a statement, the company said it is "working with the town, our union partners and the community to ensure the smoothest transition possible."
The facility, which was built and became operational in the 1960s, serves the southeast New England zone in the ISO New England market, and represents a large share of Dynegy's 6,543-MW ISO-New England and New York ISO portfolio.
Dynegy, which has become the focus of possible takeover discussions, owns a total of 31,410 MW across the country.
Dynegy took possession of the four-unit facility via a $3.3 billion acquisition of 10 power plants with combined capacity of 6,300 MW of capacity from Equipower, a unit of Energy Capital Partners, in April 2015.
ECP bought the Brayton Point facility from Dominion in March 2013. In September 2013, ECP said the Brayton plant would be shut in May 2017, citing low electricity prices as well as high costs to meet environmental standards and maintain aging facilities.
Meanwhile, in 2014, Dominion sold the Salem Harbor coal-fired power plant to project developer Footprint Power, which is building a 674-MW gas-fired facility on the site.
Footprint said on its website that the new Salem Harbor facility, located northeast of Boston, is scheduled to begin operation in June.
As of January, ISO-NE had 30,500 MW of generating capacity, with 40% being natural gas-fired, 31% nuclear, 9.7% renewables and 7.1% hydro.
Coal-fired generation represented 2.4% of total generation, the ISO said.
According to ISO-NE, since 2013 "more than 4,200 MW of primarily coal, oil and nuclear generating capacity have retired or announced retirement by mid-2020."
