What is 'Filthy Five'

The Filthy Five was a series of power plants located in Massachusetts. The Filthy Five were constructed before 1977 and were therefore exempt from modern pollution laws for many years.


The Filthy Five emitted several times the amount of pollution created by modern plants at levels that exceeded those permitted under the revised Clear Air Act of 1990. However, these plants were exempt from modern pollution regulations because they were grandfathered in under the old laws. They produced large amounts of sulfur, carbon dioxide, nitrogen dioxide and mercury. The governor of Massachusetts came under political pressure to do something about these plants and issued an edict requiring them to adhere to modern pollution regulations. 

The last of the Filthy Five power plants was Brayton Point Power Station in Somerset, Massachusetts, which was a 1,500-megawatt plant and the largest coal-fired plant in New England. It went dark in May 2017 as part of a shutdown that had been underway for several years. Other members of the Filthy Five included Salem Harbor Power Station, which stopped burning coal on June 1, 2014. Having generated power since 1951, Salem Station succumbed to low natural gas prices, weak electricity demand growth and tightening Federal pollution controls. Then Governor Mitt Romney held a press conference in Salem in 2003 and declared, "That plant kills people." The Mt. Tom power plant in Holyoke shut down in July 2014.

Transition to cleaner energy

As in other areas of the country, the end of coal in Massachusetts resulted not only from persistent environmental activism, but from a number of economic factors, including stricter pollution regulations, cleaner energy alternatives and a changing market in which coal use had become costly and inefficient. Cleaner energy options such as natural gas have largely replaced coal as a primary source of energy in the region since the closure of the Filthy Five. Nearly 50 percent of New England's energy now comes from natural gas, while a third comes from nuclear power, according to ISO New England, the organization that oversees the regional power grid. The same trend applies nationwide. Coal’s share of U.S. electricity generation fell from 52 percent in 2000 to 37 percent in 2012, thanks to a boom in shale gas development. The Energy Information Administration projects that by 2035, natural gas will generate more electricity than coal.

This transition has not come without complications. Extended low temperatures during the winter of 2017 created extreme energy demand for heat for homes. However, natural gas pipeline capacity wasn’t sufficiently expanded to meet the demand. As the region’s natural gas delivery infrastructure increases, this concern should decrease.

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