New England’s last running coal plant — the Merrimack Generating Station in Bow — was unable to complete a scheduled re-do of an emissions test it failed in February, according to state regulators.
During February testing, Merrimack Station’s emissions of particulate matter were about 70% above what’s allowed in their permit, according to an August letter from state regulators that detailed that and other documented permit violations.
In a statement before the scheduled December re-test, Granite Shore Power, which owns Merrimack Station, said they had replaced the device meant to control particulate matter emissions.
The company said that device — a “mist eliminator tray” that is part of its scrubber — failed during the February emissions test, and that test “did not represent site-specific normal operations.” But, the company asserted, the test they failed did not result in “any excessive emissions.”
The New Hampshire Department of Environmental Services said in its August letter that during the test, particulate matter was emitted at the rate that exceeded the plant’s permitted rate by 73%. State regulators also said the plant emitted too much hydrogen chloride during that test to continue its status as a “low emitting electric generating unit.”
Particulate matter pollution takes the form of tiny pieces of solids and liquids in the air. Breathing in that pollution can be harmful to human health, irritating your eyes, nose, and throat, or for smaller particles, moving into your lungs or blood.
The plant has tried multiple times to re-do the emissions test since.
In October, a retest was not completed due to a boiler going offline because of a leak. In November, a retest was scheduled for the end of the month, according to state regulators, but was not completed.
Another retest was scheduled for early December, but not completed because of a problem connecting the plant to the electric grid, according to Raymond Walters, a field operations manager in the New Hampshire Department of Environmental Service’s air compliance division.
The plant produced a large plume on the days leading up to the scheduled December emissions test, indicating that it was operating on multiple days in early December. Walters said the plant must run in order to complete the emissions test.
“To be able to do this test, they have to have both units operating at 90% to 100% of full load conditions,” he said.
To bring just one unit up to full operation can take up to 12 hours, Walters said, and in order to demonstrate full load conditions the plant would need to operate for a couple of days.
Walters says regulators are waiting for the company that owns the plant, Granite Shore Power, to schedule another retest.
“There's nothing that we have in place that would stop them from operating,” he said, but “If they're operating and they can't show us that they were in compliance, they're considered to be not in compliance.”
If the plant was operating to produce power, and not to do testing, the state could take enforcement actions, Walters said.
In August, regulators said that the plant had operated for 114 hours out of compliance with their emissions limits after their failed February stack test. The plant operated for five days in July to complete a required audit for the regional electric grid operator.
The plant generally operates as a “peaker” facility, burning coal when there is a spike in demand for electricity, often on very cold days when people use more energy to heat their homes and businesses.
Catherine Corkery, head of the Sierra Club’s New Hampshire chapter, called on regulators to ensure the plant passes an emissions test before continuing operations.
"It is incredibly disheartening to see smoke rise above the Merrimack Station smoke stack day-after-day. Without properly passing a stack test, it is uncertain whether the coal plant is operating at permissible particulate matter levels,” she said in a press release. “Exposure to PM can cause or worsen cardiovascular disease, asthma, and diabetes. Heightened pollutants put our elderly, children, neighbors with chronic medical conditions, and Concord — one of the state’s most racially diverse communities — at great risk.”
In an interview with NHPR, Corkery said the testing issues speak to larger problems with the plant, saying she sees the delays as a sign of slow decline.
“We really want to have a new chapter at the power plant in Bow,” she said. “Something that could be really beneficial not only to the grid, but to the people who need the energy, with less pollution and more reliability and something that would be cheaper than coal.”
