A power plant in Bow -- the largest coal-burning plant left in New England -- has been the target of protests and civil disobedience in recent weeks.
This month, activists from across New England have twice attempted to block trains carrying shipments of coal to the plant. Protests on the train tracks and at the plant have so far resulted in dozens of arrests.
The activists say Merrimack Station should close. Its owners argue that criticism is misplaced.
Here's what you should know about the protests and the plant's role in the regional power grid.
1. Merrimack Station is the largest of the three coal-fired power plants left on the New England grid.
New England has never been as heavy a user of coal as are regions that sit closer to coal reserves – like Appalachia and the Midwest. But the Northeast did at one point have several big coal plants supplying round-the-clock power – including Merrimack Station, built in the 1960s.
But a lot has changed since then. Big nuclear plants like Seabrook Station came online in the 1970s; air pollution and emissions rules grew tighter over time; and cheap natural gas boomed in the 1990s and 2000s.
As a result, over the past 20 years, amid a growing sense of urgency about combating climate change, all of New England’s biggest coal plants have shut down.
Some switched over to natural gas. Others were demolished. The site of one plant, razed in 2018, may one day host offshore wind infrastructure. Many coal plants just couldn’t compete while paying for required environmental upgrades.
That’s left three coal-fired power plants in the region.
Two are in New Hampshire, owned by Granite Shore Power: Merrimack Station in Bow, and the much smaller Schiller Station in Newington, which also burns oil and woodchips. The third is Bridgeport Station in Connecticut, which is being replaced with natural gas and will retire by 2021.
2. The power plant now runs more rarely than ever – though "rare" is relative.
Merrimack Station was built as a “baseload” plant – one that supplies a large, steady supply of power regardless of conditions on the grid. These days, it’s become what’s known as a “peaker” – a resource that only comes on when the grid is stressed and in need of extra electricity.
These days, New England’s grid mostly runs on natural gas and nuclear power. Merrimack Station is typically fired up only on the hottest days of the summer months – when air conditioning use drives up energy demand – and on the coldest days of winter – when natural gas supplies are put toward heating demand, and the electric grid needs a boost.
To put that in context: Twenty years ago, when bigger coal plants were still online, New England burned several million tons of coal a year to meet nearly a fifth of its total electric demand.
Last year, that was down to about half a million tons of coal burned to meet about 1 percent of total electric demand. At least half that coal was burned at Merrimack Station.
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Government data says in 2018, the plant ran most in January – serving its function during a historic cold snap that stretched the region’s oil and gas capacity to the brink. After that, Merrimack’s busiest months were February, April and December, with a bit more production in early and late summer. The plant was only totally shut down for three months out of the year.
In terms of emissions, Merrimack put out about 722,000 tons of carbon dioxide in 2018, compared to more than 3 million tons in 1995, according to the Environmental Protection Agency -- a bigger decrease than the average change in that period nationwide.
The EPA also says the plant's 2018 carbon emissions were equivalent to the annual emissions of nearly 140,000 passenger vehicles, or, for another comparison, to the annual electricity use of 114,000 homes.
Within its sector, Merrimack contributed about 1 percent of the region’s emissions from electric generation in 2018.
3. The plant is not the only front in New England where climate activists are protesting.
The president of Merrimack Station’s parent company, Jim Andrews, says he believes activists’ focus on the plant is misplaced.
He points out that home heating and automobiles are far bigger, more entrenched sources of fossil fuel emissions in the region than what Merrimack Station is contributing.
But the facility is not the climate protesters’ only target.
Many of the same groups that have fought against the plant are also organizing to oppose new natural gas infrastructure in Massachusetts and New Hampshire, rallying for offshore wind and solar power, and calling for more electric vehicle infrastructure and home efficiency funding in the region.
The campaign against Merrimack Station is just part of their bigger push to stamp out the last vestiges of coal and oil from New England’s grid.
4. Almost everyone agrees it's inevitable that the region will transition off of coal and oil. The big questions are when and how.
Jim Andrews, the president of Merrimack’s parent company, says New England is well on its way toward a future without these legacy fossil fuels.
He sees his plant as a bridge to getting there, and says they may even build energy storage systems on site in the future. Those systems could be used, like the plant itself, to provide a back-up source of cheap energy when demand or prices get too high.
As for when the power plant may close down entirely, he says the market will dictate that.
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If you're wondering whether the grid could survive without Merrimack Station, the answer is likely yes -- the system is full of redundancies and backups to account for the loss of a small slice of power.
But it might affect energy costs. Coal is not the region's only option to supply extra power on high-demand days, but right now, it is the cheapest. Using a more expensive alternative could potentially pass costs onto customers.
Still, economic conditions could change. Putting a price on carbon, an idea popular with many activists, energy economists and some policymakers, would make coal and all fossil fuels much more expensive.
There's also the cost of operating Merrimack Station. The plant made its most expensive recent environmental upgrade – a mercury scrubber to clean up its emissions – back when it was still owned by what's now Eversource, meaning ratepayers bore the cost. Now that the plant competes on the open market, any unexpected capital costs could change its economic outlook.
But protesters who have targeted the plant don’t want to wait. They say they’re going to spend this winter calling for the plant to close – and they have promised to risk arrest again in the coming months, attempting to delay or disrupt every shipment of coal the plant receives by rail.