A Massachusetts town uses batteries to help its grid — and its schools

Some batteries serve to bolster utility power grids. Other batteries provide backup power to buildings in case the grid goes down. And sometimes, with effort and coordination, batteries can do both jobs at once.

That’s what’s happening in Wakefield, Massachusetts, a town of about 27,000 just north of Boston.

By next year, a site off a tree-lined road running between the town’s two high schools will host a 15-megawatt-hour grid-connected battery that will provide multiple benefits. On a day-to-day basis, it will help clean up the grid and keep utility costs in check by reducing the need for costly peak energy. It will also supply backup power to the schools during any power outages, eliminating the need for dirty diesel-fueled generators. Plus, the battery will help the schools afford to go solar and switch their HVAC to electric heat pumps. 

Getting the Energy Park Project off the ground took a lot of coordination between the two schools, city agencies, city-owned utility Wakefield Municipal Gas & Light Department (WMGLD), and a consortium of state municipal utilities contracted with a private-sector battery developer to build the project. 

But the payoff will be a cheaper and cleaner solution than what either the utility or the schools could have achieved on their own, said Peter Dion, WMGLD’s general manager. 

As a city-owned utility, WMGLD has a clear incentive to find solutions to these shared civic challenges, he noted. Unlike investor-owned utilities, which aim to earn a profit by serving city governments, schools, and other customers, municipal utilities contribute revenue to and receive funding from the budgets of the cities they serve. 

Investor-owned utilities must also win state regulators’ approval for novel projects that provide special treatment to individual customers. Beyond pilot projects, only a handful of U.S. utilities have taken major strides in supporting batteries that serve both customer and utility needs; Vermont utility Green Mountain Power’s bring-your-own-battery program is one noteworthy example. 

Municipal utilities, on the other hand, ​“can be more nimble” in collaborating on projects like these, Dion said. ​“We only answer to the citizens of Wakefield.” 

The path from all-electric school buildings to shared backup batteries 

The idea for Wakefield’s Energy Park was born out of a problem Dion started to tackle back in 2021: how to provide the energy needed for new buildings at Northeast Metropolitan Regional Vocational High School and Wakefield High School.

“They’re both undergoing a plan to build new schools on their properties,” Dion said. Those new school buildings will need heating, and though it would have been cheaper for the schools to use fossil gas, that route made less sense from WMGLD’s perspective. 

“The biggest driver of our costs on the gas side is the peak load on the coldest day of winter,” Dion explained, and the amount of gas those schools would use outside those coldest days wasn’t enough to recoup the cost of building the pipes to deliver it. 

The schools were also eager to explore all-electric buildings, both to meet state decarbonization mandates and because they wanted to be ​“as green as possible,” Dion said. Similar dynamics are leading regulators in many states with decarbonization goals to question the wisdom of investing in gas-delivery infrastructure and to push utilities to explore ​“non-pipeline alternatives” like electric heat pumps. 

The challenge? While heat pumps are far more energy-efficient than gas furnaces and boilers, they’re still more expensive upfront — and schools have limited capital budgets to cover those higher costs. Dion and the schools began to consider where they could shave some expenses from the new school buildings to make up the difference. 

That’s how batteries came into the picture, Dion said. Plans initially called for both schools to install diesel backup generators for the new buildings, which would have cost about $1.2 million apiece — a hefty price for equipment that only runs during emergencies. ​“From an environmental perspective and from a cost perspective, that’s not great.” 

Grid-connected batteries, by contrast, can pay back their costs by storing power when it’s cheap and plentiful and discharging it when it’s far more valuable — like the handful of hours per year when demand for electricity on New England’s regional grid reaches its peak. WMGLD deployed a 5-megawatt-hour grid battery in 2019, which it’s been using to cut the capacity costs it must pay grid operator ISO New England for those peak hours, Dion said. 

And while the batteries are meeting these grid needs, they can still be available for other purposes — like serving as backup power for buildings. 

That’s the proposal WMGLD brought to the city’s two high schools, Dion said, telling them, ​“We can eliminate about $1.2 million of your costs by building this Energy Park, and us being your backup generator.” 

Getting the details right 

Designing a utility battery that can both work for the grid and back up buildings isn’t necessarily simple. 

It helped that the two high schools WMGLD is working with are next door to each other, allowing the utility to build a shared grid circuit to connect them to the Energy Park. That simplifies the technical aspects of the project, Dion noted: ​“At each high school we’ll have an emergency transformer that will be live at all times, and at moments of lost power, that will be their emergency generator.” 

Still, the utility has had to plan ahead for the contingency that the battery might discharge most of its stored energy for grid purposes at the moment when the grid goes out. ​“Probability being what it is, the day we’ve drained it down to zero is the day we need it for emergency backup,” he joked. 

To deal with that possibility, WMGLD added a 2.5-megawatt fossil-gas-fired generator to the Energy Park as a secondary backup. That’s still cheaper than two diesel backup generators, he noted — and it will kick in only in the worst-case scenario. 

WMGLD will also retain at least 7.5 percent of its battery capacity at all times, which is enough for about an hour of backup power — plenty of time to get the generator going. During normal operations, the batteries will stand at 50 percent charge, enough for about six hours of backup power. Most distribution-grid outages last no more than an hour or two, he said. 

Some of that battery-charging power could come from the solar panels that WMGLD will install on the roofs of the new buildings. The utility has structured a deal that will take on the cost of that installation for the schools, in exchange for the schools agreeing to give all the solar power they don’t use back to the utility at no additional cost. 

That kind of arrangement would be tricky for investor-owned utilities, which are held to state regulations about whether they can own solar on customers’ properties and how the value of that solar power is compensated. 

As a municipal utility, WMGLD has more freedom to negotiate these kinds of structures, which will allow it to pay off the cost of the installation in nine or 10 years — partly because it can use the solar power to meet its own needs during summertime, when schools are closed and ​“solar value is the highest” for reducing summer electricity demand. 

All told, the package of batteries and solar is expected to reduce total energy-related carbon emissions at the two high schools by nearly half compared to the alternative. 

Can sharing batteries between utilities and customers scale up? 

WMGLD won’t build or own the batteries at the Energy Park — and it won’t pay for them either. That’s all being handled by Lightshift Energy, a Virginia-based energy-storage developer that’s raised $120 million in equity and project finance and has 4 gigawatts of projects in its pipeline. 

“We’ve spent a lot of time focused on distribution-connected storage,” said Mike Herbert, the company’s managing partner and co-founder, referring to batteries that connect to the lower-voltage grid circuits and substations that deliver power to customers rather than the high-voltage transmission grid. 

Wakefield’s Energy Park is among the first in a 50-megawatt portfolio of battery projects Lightshift is developing in partnership with the Massachusetts Municipal Wholesale Electric Company (MMWEC), a ​“joint action agency” that works with most of the state’s 40 municipal utilities to procure wholesale power supplies and raise project financing.

The portfolio is forecasted to save participating utilities more than $200 million in capacity and transmission costs, Herbert said. ​“If you’re a town of a few thousand people and looking at $20 million or so of savings for a 5-megawatt battery, it becomes a very compelling economic story.” 

While some of the country’s largest electricity providers are municipal utilities, such as the Los Angeles Department of Water and Power, most are small and inexperienced with battery installations, said Jason Viadero, MMWEC’s director of engineering and generation assets. They also typically lack the deep pockets of larger investor-owned utilities. 

That’s why most of the batteries deployed by the state’s municipal utilities have been backed by state grant funding to date, Viadero said. 

In contrast, MMWEC’s contract with Lightshift means the developer foots those upfront costs and recovers them through its shared-savings structure with utilities. 

Lightshift, in turn, can buy larger volumes of batteries, standardize the process of building and interconnecting them to the grid, and manage them through its software platform, Herbert said — all tasks that would be more expensive for individual utilities working on their own. 

Viadero noted that the cost factor is key. Municipal utilities in Massachusetts are currently dealing with rising wholesale electricity costs at the same time that they’re being asked to convert more and more customers from fossil fuels to electricity. ​“We don’t want to tell people to install a heat pump and then pay more than they’re paying for their gas heating,” he said. ​“If we can drive down the cost of our wholesale power by utilizing these batteries, that’s going to make a world of difference.” 

Not all of MMWEC’s battery projects can tie in backup power, but a growing number of cities are looking for ways to do it, Herbert noted. In Groton, Massachusetts, Lightshift is developing two 9-megawatt-hour systems for municipal utility Groton Electric Light Department — one at a substation and another on the property of an elementary school. 

Backup power will become increasingly important as more and more buildings switch from fossil fuels to electricity for heating. ​“We like tackling those use cases,” Herbert said. 

At the same time, Lightshift is hoping to scale up its shared-savings battery development model with municipal utilities in other regions. ​“At a regional scale, where you’re having trouble building new transmission, having trouble building new capacity, and you have rapid load growth, these projects have multiple benefits.”