Sometime in May, two 53-foot-long storage containers, each fitted with roughly 950 lithium-ion batteries, are scheduled to be trucked to an industrial park in Rumford.  

The batteries for this $5 million project will be charged at night with cheaper electricity, when demand in New England is low. The next day, when homeowners turn on appliances and business ramps up, the region’s grid operators in Massachusetts can remotely dispatch those batteries and send enough power flowing to run 4,000 or so homes for up to two hours.

By calling on giant battery banks when needed, operators at ISO New England can reduce the use of more costly and pollution-emitting fossil fuel generators, soak up excess output from a fast-growing fleet of solar and wind projects, and help keep the region’s electric system stable and reliable.

At Rumford, and at a similar 4.99-megawatt project in Madison, the project’s owner earns money by selling the stored energy when it’s most advantageous. The company, New England Battery Storage of Boston, is planning a comparable project in Sanford and another one twice as large in South Portland.

Maine policymakers want to encourage such projects as another tool to help meet the state’s ambitious climate goals. On Tuesday, the legislative committee that handles energy and utility matters is scheduled to hear a bill meant to advance energy storage in the state. It would set a target of installing 100 megawatts by 2025.

But based on recent developments, that goal may be overtaken by market forces.


It was notable news in energy circles last month when Plus Power, a San Francisco-based battery plant builder, won two bids at ISO New England, which operates the region’s electric grid, to build giant battery storage projects. One of them would be located in Gorham. Rated at 175 megawatts, it would become the largest storage project in the region if and when it comes online as scheduled in 2024.

The Plus Power projects also are noteworthy because the grid operator selected them as part of an annual auction program meant to assure that the region has enough generating capacity three years from now at the lowest prices. Under new rules, ISO New England treats giant batteries as it would a power plant. In the most recent auction, nearly 600 megawatts of energy storage capacity was approved.

All this activity is heartening to Maine Sen. Eloise Vitelli, D-Arrowsic.

Vitelli headed up a legislative study group on energy storage in 2019. After hearing from developers and other stakeholders, the group recommended a modest, non-binding goal of 100 megawatts of new capacity by 2025.

Then the pandemic hit, and the bill languished until this week. Now Vitelli said she’s wondering if the state should aim higher.

“That was a year ago, and things are moving very fast in this industry,” she said. “We were being modest. I’d be more than open to amending the legislation to try to take advantage of the current situation.”


The energy storage boom is set to accelerate nationwide, according to a new, widely cited report by global energy consulting firm Wood Mackenzie. It noted that more battery storage facilities became operational in 2020 than in the previous six years combined. Most were large-scale installations by utility companies.

Not included were thousands of hard-to-count home-sized systems being bought by people with rooftop solar systems. They use the batteries to take advantage of rate-reduction programs at some utilities and as a buffer against storm-related blackouts.


Maine’s energy storage landscape has changed drastically over the past few years.

In 2016, NextEra Energy Resources installed a 16-megawatt battery at its Wyman Station oil-fired power plant in Yarmouth. It was the largest in New England at the time and helps the grid operator regulate the daily changes in supply and demand.

Hundreds of special-purpose batteries fill racks inside one of three shipping containers in Boothbay that make up New England’s first utility-scale electricity storage system, in a photo from 2015. Photo courtesy of Convergent Energy

Before that, a project roughly one-fifth the size of Wyman’s was installed in Boothbay. It’s part of a pilot program for storage to meet the need for power in the area without building a new transmission line.


Most recently, Brookfield Renewable Energy Partners, a Canadian company that operates hydroelectric dams in Maine, installed a 20-megawatt battery plant in the Millinocket area. A Brookfield executive said the economics were favorable because the dams already had the needed power connections to get on the grid.

In addition to Rumford, New England Battery Storage has a second project operating in Madison rated at 1.5 megawatts. That one helps lower the cost of peak-demand power for the local municipal electric company.

One attribute driving the move to battery storage is that power can be dispatched within milliseconds, said Jeff Perry, the company’s president and chief executive. That creates more flexibility for grid operators.

“The value of batteries is getting the power at the right time,” he said.

Specifically, grid operators use scheduled pricing and dispatch algorithm tools that economically suggest which power resources should charge and/or discharge to meet the supply-and-demand balance at a given moment.

Maine is a good place to site storage projects, Perry said. It has several locations where former makers of forest products have shut down, leaving behind strong electrical infrastructure. Perry said he has found it easy to permit battery projects, which have a relatively small footprint. And contrary to the experience of some large solar developers, he said he hasn’t had trouble connecting to Central Maine Power’s distribution system.


“It’s a pretty friendly environment for business,” Perry said of Maine.


Maine also is attractive for battery storage because of its geographical position relative to a growing fleet of solar and wind projects. That’s what attracted Plus Power, which is developing its Gorham project as Energy Storage Resources LLC.

A company spokeswoman declined last week to discuss project details with the Portland Press Herald. She said the company had just received approval from ISO New England and was working on permitting and design.

But Polly Shaw, Plus Power’s communications head, did confirm reports in industry media that locating between large wind farms in northern and eastern Maine and the Boston area’s electricity demand was key. The big battery plant will be able to relieve power constraints on the network better than gas-fired generation plants, which aren’t as nimble as batteries, take longer to build and can face opposition.

Plus Power’s second big battery is slated for Carver, Massachusetts, near Cape Cod. That’s not far from the landing point for cables from pending offshore wind projects in Massachusetts. The batteries could charge overnight on less-expensive wind power, then discharge during hours of peak demand and higher prices.


Energy planners in Maine anticipate similar large batteries could someday be sited at Wyman Station and the former Maine Yankee nuclear plant property, to soak up power from floating offshore wind farms there.

Pairing renewable power generation with storage increases the value of battery plants, according to a recent market assessment done for the Maine Governor’s Energy Office. That combination will be especially important in the winter, as Maine shifts more home and business heating to heat pumps, part of the process to phase out oil and gas and electrify the state’s economy.

“Pairing solar with storage improves the combined generation profile of these hybrid resources, enabling them to generate during evening peak demand, increasing their value to the system,” the reported noted.

Dan Burgess, who heads the governor’s energy office, said the assessment also found that adding storage to solar projects greatly increased the overall capacity of solar energy. Burgess noted that several solar projects waiting for interconnection agreements with CMP and Versant Power also feature storage, adding up to 250 megawatts. Not all those projects will get built, and not all will keep batteries in the mix.

“But it is a sign of interest,” Burgess said.

Burgess said the administration of Gov. Janet Mills may offer its own take on the current storage bill, but no decision had been made public yet. He said he looked forward to the bill’s hearing and fresh input from developers and stakeholders.

“The world is changing pretty quickly,” he said, referring to the Plus Power proposal. “A few weeks ago, we didn’t have a 175-megawatt project.”

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