Merrimack Station, which is New England’s last running coal plant, will stop operating in 2028.

Granite Shore Power announced the closure of the Bow plant as part of a settlement agreement signed Wednesday, resolving litigation brought by the Conservation Law Foundation and the Sierra Club. Granite Shore Power will commit to shutting down coal-fired generators at the Schiller Station in Portsmouth by 2025. Currently, that plant has the capability to burn coal but hasn’t used its coal-fired generation since 2020.

Merrimack Station is a peaker plant, used to provide power on the region’s hottest or coldest days. In New England, coal makes up less than one percent of the region’s energy.

Granite Shore Power says the two plants will become “renewable energy parks.” Schiller Station is set to host a battery storage system that can provide power to the grid when there’s a lot of demand, and could serve as storage for offshore wind power.

Merrimack Station is expected to host about 100 megawatts of solar, along with more battery storage. As of 2023, New Hampshire has about 260 megawatts of solar power in total.

“I think we're undertaking a bold step forward and making good on a promise to transition our coal fired plants to clean energy facilities,” said Jim Andrews, the president and CEO of Granite Shore Power. “I think these facilities will pave the way for New Hampshire to be a leader in the clean energy economy.”

Andrews said he’d been planning to transition the plants away from coal-fired generation since Granite Shore Power bought them in 2018.

For Tom Irwin, a Vice President at the Conservation Law Foundation, the company’s commitment to stop burning coal symbolized a win for advocates. He said the settlement agreement was a result of “hard-fought litigation.”

“It's a big moment. Coal is the dirtiest form of energy that we have. It’s essential to address the climate crisis that we get off fossil fuels and make that transition to a clean energy economy,” he said.

Catherine Corkery, the head of New Hampshire’s Sierra Club chapter, said she was excited about the closure of the plants – not only for the environment, but also for public health.

“It remained a very significant health risk,” she said. “The largest single source of pollution in New Hampshire is going away. That's a real accomplishment for public health and for kids that have asthma and parents who have kids who have asthma.”

Advocates have called for the closure of one of Merrimack Station for years , with dozens of people being arrested after protesting Granite Shore Power’s use of coal in 2019 and 2023.

The group No Coal No Gas has called on the owners of the plant not to transition to gas, like many other plants in the US have done. Andrews said he had no current plans to use gas at the plants, but the company intends to “optimize the grid for reliability,” which he said would require a “balanced mix of generation.”

The plant has faced regulatory scrutiny in the past year. New Hampshire state regulators have ordered the plant to comply with state emissions regulations by the end of this month. Merrimack hasn’t been able to test its emissions since February 2023, when it exceeded one emissions limit by about 70%, according to state regulators. As of February 2024, it had operated for more than 500 hours in violation of its permit.

Read more about the plant’s emissions compliance here . 

Merrimack Station has tried on four separate occasions to retake the emissions test, but has canceled each attempt due to issues including boiler leaks and an electrical breaker issue.

Andrews said the plant would demonstrate to state officials that they were operating in compliance with their permit, and continue meeting their obligations to provide power to the regional grid. The plant has an obligation to provide power to New England through 2026, but may extend that through 2027.

According to the Sierra Club, the closure of the Merrimack and Schiller plants will make New Hampshire the 16th state to eliminate coal. New England will be the second U.S. region to transition away from coal, after the Pacific Northwest.

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