Filthy Five

Filthy Five

Investopedia / Mira Norian

What are the Filthy Five?

The Filthy Five refers to five power plants that were located in Massachusetts. The Filthy Five were constructed before 1977 and were therefore exempt from modern pollution laws for many years.

Key Takeaways

  • The Filthy Five was a name given to collectively to five coal-fired power plants in Massachusetts.
  • The plants had been in operation for decades using older, dirty technology, but were permitted to continue operation under the federal Clean Air Act.
  • The last of the Filthy Five ceased operation in 2017.

Understanding the Filthy Five

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 legacied 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. The Salem Station generated power beginning in 1951, but shuttered due to low natural gas prices, low demand for electricity, and tightening Federal pollution rules.

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. The share of U.S. electricity generate by coal fell from 52 percent in 2000 to 37 percent in 2012 as a result of shale gas development. The Energy Information Administration predicts that natural gas will produce more electricity than coal by 2035.

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.

Article Sources
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  1. General Accounting Office. "Status of Implementation and Issues of the Clean Air Act Amendments of 1990," Page 27. Accessed Mar. 5, 2021.

  2. "Salem Harbor Revitalization Task Force," Pages 4-5, 11-12, 28, 38-39. Accessed Mar. 5, 2021.

  3. ISO New England. "Reliable Electricity. Competitive Prices. Clean-Energy Transition." Accessed Mar. 5, 2021.

  4. Energy Information Administration. "Electricity Explained." Accessed Feb. 3, 2021.

  5. Energy Information Agency. "Analysis of Impacts of a Clean Energy Standard as requested by Chairman Hall." Accessed Mar. 5, 2021.

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