Enormous new batteries keep appearing on the grid, making it devilishly tricky to keep track of which is the biggest in a given region. That’s certainly the case in New England, where acute power needs and robust state climate goals are fueling a buildout of big batteries that keep breaking capacity records.

Canary Media recently covered the inauguration of the 175-megawatt Cross Town battery in Gorham, Maine, which was the largest in New England when it began operating in late November. But that trophy has already passed to a 250-megawatt facility in Medway, Massachusetts, southwest of Boston and about 10 miles from the Patriots’ Gillette Stadium.

The Medway battery came online fully Feb. 25, according to developer VC Renewables, a subsidiary of global energy trader Vitol.

“To be fair, I don’t expect Medway to hold that title for very long, either,” said Tom Bitting, managing director at Advantage Capital, which supported the project with a $158 million tax equity deal. ​“There are other batteries being developed in New England that are bigger, but I think it is all just a sign that we need all of it, and there’s huge demand for it.”

For instance, Jupiter Power, a heavyweight in Texas’ booming grid storage market, is developing the 700-megawatt/2.8-gigawatt-hour Trimount battery plant at a former oil-storage site in Everett, Massachusetts, just north of Boston. Jupiter aims to finish the project in 2028 or 2029. Trimount is slated to be among the largest stand-alone batteries in the whole country — Vistra’s battery in Moss Landing, California, set that record with 750 megawatts/​3 gigawatt-hours, before much of that capacity burned up in a disastrous fire.

The wave of battery megaprojects marks a new chapter for the region, which until recently was focused on building small-scale batteries. Massachusetts encouraged this by requiring energy storage alongside many distributed solar projects that received payments through the state’s main solar incentive; this rule led to a buildout of systems in the range of 1 to 5 megawatts.

Bigger batteries started taking off in the late 2010s out West: in California, Arizona, and Nevada, where developers can sign long-term contracts to deliver grid capacity; and in Texas, where they can bid into a uniquely competitive market.

The first three big batteries in New England — Plus Power’s Cranberry Point and Cross Town, as well as Medway, which was previously developed by Eolian — won seven-year contracts in 2021 to provide capacity for the New England grid, but the grid operator subsequently shortened that kind of contract to one year. After that change, developers have struggled with the lack of long-term capacity revenue; they can still charge up when prices are low and sell when they’re high, but that’s an unpredictable revenue stream that financiers might not want to underwrite.

Massachusetts has succeeded in building a robust fleet of small-scale solar — on recent sunny spring days, it has generated close to 50% of the region’s demand. But leaders knew they needed batteries to keep cleaning up the grid in the hours when solar doesn’t produce. So they created a new policy driver for storage investment called the Clean Peak Standard, which officially took effect in 2020.

The rule orders utilities to serve a percentage of their peak-demand hours with clean electricity, and the target grows with each passing year. Companies that use batteries to save solar energy for the evening — when electricity consumption rises as people get home from work and school — earn credits that they can sell to utilities, providing some revenue certainty outside the wholesale market.

The administration of Gov. Maura Healey, a Democrat, views storage as a key lever to improve energy affordability, Undersecretary of Energy Michael Judge said, because it makes better use of existing grid infrastructure to meet peak demand.

“Store all that solar energy that we’re producing in the middle of the day and bring down the cost of operating the system for everyone,” he said. ​“You don’t have to run these peakers, and you get all the emissions benefits and integration of clean energy benefits, too.”

It took several years for the rule to actually spur batteries in the multihundred-megawatt range, but now that era has begun. Advantage Capital, for example, factored in revenues from the Clean Peak Standard when it analyzed and underwrote the investment in the Medway project, Bitting noted. A total of 725 megawatts of battery storage had qualified for the Clean Peak Standard as of early March, according to state data.

Stand-alone grid battery projects are also bolstered by a federal tax credit that can cut investment costs by 30%, an incentive that the Trump administration preserved in last summer’s budget law even as it slashed support for wind, solar, and electric vehicles.

Clean Peak cash alone doesn’t pay the bills; battery developers still need to make money in the marketplace. Though New England lacks long-term capacity contracts, storage companies in the region have at least two factors working in their favor: some of the nation’s highest electricity prices and growing demand for power.

“It’s very difficult to get additional generation online in an area with high population density, because regardless of what type of power generation you’re building, it requires a lot of space,” Bitting said. Batteries, though, can fit a lot of power into a relatively small footprint, without the smokestacks or pollution that make it hard to build new fossil-fueled plants in populous areas.

Batteries compete directly with gas power plants to serve the peak hours of demand, when prices are highest. That’s especially valuable in New England, where gas supplies are stretched thin between power generation and home heating on the coldest days of the year.

“When it’s cold, the households are going to continue to demand it,” Bitting said. ​“But if we can ease some of the peak on the utility side, that will provide a relief valve to supply.”

Jupiter Power’s colossal Trimount project will continue New England’s foray into large batteries, with the ability to discharge enough power for roughly 500,000 homes, per the developer. Trimount was the largest of four battery projects selected in December from Massachusetts’ statewide solicitation to bring on more Clean Peak power. Previously, battery owners could sell off their Clean Peak credits on a quarterly or annual basis. The new solicitation was designed to produce ​“cost-effective” long-term contracts for storage, giving developers more stable revenue to plan around. Furthermore, Healey doubled down on grid storage in a March 16 executive order that calls for another 5 gigawatts installed by 2035.

“That kind of policy signal, combined with the state’s grid reliability challenges and its decarbonization commitments, creates the conditions for investment at scale,” Hans Detweiler, senior director for development at Jupiter, said in an email.

Massachusetts officials also hope to speed development with new permitting rules, which run large battery applications through a state-level body instead of piecemeal local processes. Community members still get to weigh in, but the program has a clear 15-month timeline and allows just a single appeal to the state Supreme Court, to ensure a more timely resolution of conflicts in the permitting process.

The true test of all these policies will be whether the recent megabatteries kick off a trend, or remain bold outliers in the region’s energy system.

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Julian Spector

is a senior reporter at Canary Media. He reports on batteries, long-duration energy storage, low-carbon hydrogen, and clean energy breakthroughs around the world.