It’s official: The coal- and oil-fired Salem Harbor Station north of Boston, scheduled to be retired next year, will be replaced with a fast-ramping natural gas combined cycle plant.

The four-unit, 720-MW plant, which was built on the site of an existing coal terminal in the 1940s, was sold by previous owner Dominion Resources to Footprint Power, a New Jersey–based merchant power firm, last year. The two oldest units were shut down in 2011, and Dominion had repeatedly sought to retire the last two operating units because of emissions concerns, only to be turned down by ISO-NE. The plant’s fate was finally sealed by a settlement between Dominion and a coalition of environmental groups that set the plant for retirement in 2014. Dominion sold the plant to Footprint later that year.

Footprint then applied for a permit to remove the old plant and build a new gas-fired facility on the site. It cleared the February 2013 ISO-NE forward capacity auction to begin supplying power in June 2016, and will receive a five-year capacity payment to incentivize construction. Formal approval for the project from the Massachusetts Energy Facilities Siting Board was issued on October 11. The new plant will be Footprint’s first such project.

On November 1, Footprint and General Electric announced that the new plant would use GE’s FlexEfficiency 60 technology. The 674-MW plant will employ two 7F 5-series gas turbines in 1×1 configuration, and will include the first GE Rapid Response power islands to be deployed in New England. The plant’s fast-start capability will enable it to add 300 MW of power to the ISO-NE grid within 10 minutes, and it will be one of the cleanest and most efficient fossil plants in New England.

The new plant will occupy only 20 acres of the existing 65 acre site, opening up public access to approximately 40 acres of waterfront land. The remaining acreage will be redeveloped, and the plant will employ a low-profile design to reduce visual and noise impacts on the surrounding area. The three existing stacks, each nearly 500 feet high, will be replaced by a single 230-foot stack. The plant will employ air-cooled condensers, saving hundreds of millions of gallons of seawater that were needed to cool the old plant.

Though the new plant is expected to reduce regional emissions, it is likely to exacerbate New England’s heavy dependence on natural gas. Regional pipeline constraints are not expected to ease meaningfully until Spectra’s Algonquin Incremental Market (AIM) pipeline project comes online in 2016, the same year the new Salem plant will begin service.

Thomas W. Overton, JD, gas technology editor (@thomas_overton, @POWERmagazine)