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. Similar batteries could soon supply power to customers in the Brunswick-Topsham area on high-demand days. Photo courtesy of Convergent Energy

On a scorching summer evening a few years from now, big batteries at locations that might include Bowdoin College or the Topsham Fair Mall could discharge for five hours or so into the area’s electric distribution system. Commercial air-conditioning units around Brunswick and Topsham may briefly cycle down to reduce power demand, along with refrigeration units at supermarkets and restaurants.

These and other measures will help assure that the lights stay on during periods of high power demand for roughly 8,000 Central Maine Power customers in Brunswick, Topsham and Harpswell.

CMP could achieve a similar level of reliability in this area by totally rebuilding an aging, 5-mile transmission line. But energy experts found that just installing new poles and wires would be a more expensive solution. Instead, they’ve come up with a strategy to trim power use at crucial moments. If it works, the old transmission line will come down.

Maintaining reliability without new transmission lines is called a “non-wires alternative.” The alternative plan ramping up soon in Brunswick and Topsham was approved this month at the Public Utilities Commission. It’s the first case under a 2019 law aimed at reducing future electric costs and, in this instance, projected to save customers $8.5 million over the project’s lifetime.

That’s not a big number by itself, and it’s a savings off bills years in the future. But the recent PUC approval is worth noting because it’s part of a new way of planning utility investments in Maine. It’s happening as New England faces the potential of spending billions of dollars to upgrade the grid to handle an accelerated shift to an electrified economy, a future of plug-in cars and heat pumps, powered largely by solar and wind generation.

Part of that planning process is making sure the state’s transmission and distribution systems can handle demand during the hottest and coldest hours of the year, when air conditioners are blasting or heaters are straining. Non-wires alternatives such as battery storage and energy efficiency hold the promise of maintaining reliability without building costly transmission capacity that’s rarely needed.


In this instance, power now flowing over the old transmission line will be rerouted to different, existing circuits that will undergo some cost-effective upgrades. That’s how electricity will get to the batteries, and to everything else.

Think of it like highway construction, said Michael Stoddard, executive director of Efficiency Maine, the state’s conservation agency. It’s expensive to build and maintain extra travel lanes on a highway that are only congested during holiday weekends.

“This is like being able to get away with one less lane on the highway,” Stoddard said.

Efficiency Maine Trust, CMP, the Office of Public Advocate and a consultant the office hired to help analyze the Brunswick-Topsham power line worked together to come up with the non-wires alternative. The next step, which will take a couple of years, is to put it all in place.


The existing power line runs through residential areas of Brunswick and a growing commercial section of Topsham. The impetus for the project dates to 2018, after CMP performed a survey of its transmission system. It found a half-century-old section between two substations, known as Section 31, was in poor condition.


The initial solution was to install 107 larger, stronger wooden poles in CMP’s 100-foot wide right-of-way, next to the old line. The cost of the job grew over time from roughly $9 million to $14 million and was expected to be in service this year.

But a 2019 law changed that trajectory. It requires utilities to work with state agencies to identify non-wires alternatives for projects above a certain size and cost. Section 31 met that standard.

The Public Advocate’s office hired DNV, a global consulting firm with an office in Portland. It worked with CMP to study the condition of Section 31, using drones to inspect pole tops and cross arms. They concluded that the line wasn’t in as bad shape as initially thought and that a rebuild could be deferred while a non-wires alternative was devised.

That was welcome news for some Brunswick homeowners who lived next to the power line corridor. Over the years, some of them had improperly put in gardens, fences and swing sets in CMP’s right-of-way. They feared losing part of their assumed backyards to a new set of poles and wires.

Staff graphic/Jake Laws

After studying several options, CMP and the parties arrived at a hybrid non-wires alternative. That means the solution isn’t strictly no-wires. It also incorporates cost-effective, conventional upgrades to some circuits and adds a new transformer to help meet reliability standards.

This alternative plan was spelled out in an agreement among CMP, the Public Advocate’s office, Efficiency Maine and the Brunswick neighbors. It was approved June 28 by the PUC. There was, however, an unintended consequence. Three solar farms being developed in the area with plans to interconnect along Section 31 were left out of the process and now face additional costs and delays. The PUC is expected to take up their concerns in a subsequent proceeding.



Now, the work begins.

Details are pending, but through a competitive bid process, a contractor will work with CMP and Efficiency Maine to figure out how to size and locate the battery storage. The agreement calls for storage capacity of 1.7 megawatts that can be discharged when needed – likely on the hottest hours of the summer – over a period of up to five hours. In New England, that period tends to be in the early evening. The region’s growing fleet of solar farms have tapered off by then, but people are still cranking the AC to stay cool.

Maine has several battery storage projects and new ones are being planned. A 4.99-megawatt battery storage project installed last year in Rumford contains 950 lithium-ion batteries and is designed to send enough power flowing to light 4,000 homes over two hours. Battery projects like these tend to charge up at night, when demand slackens and wholesale power costs fall.

In addition, Efficiency Maine will be working with scores of area businesses and institutions, such as hospitals, retailers, schools and factories, to upgrade HVAC systems and undertake efficiency measures, such as more-efficient lighting and industrial motors.



Although a new law set the Brunswick-Topsham project in motion, Maine does have some experience with non-wires alternatives.

In 2014, CMP and Portland-based Grid Solar worked on a pilot project in Boothbay designed to offset the need to rebuild a transmission line to the peninsula. The project involved a range of strategies: Changing out wasteful light bulbs in stores and other businesses; small solar arrays; a 500-kilowatt battery storage system; a diesel-fired generator for backup; an innovative air-conditioning system using ice and a variety of demand-response arrangements, in which companies agrees to turn down motors or non-critical equipment during peak hours.

The pilot provided important lessons for Maine, but after the area’s electric growth was less than forecasted, the project wasn’t extended and the results are inconclusive.

Once all the elements of the Brunswick-Topsham project are up and running, CMP and the parties will have two years to assess whether reliability standards are being met. If they are, the substation in Brunswick will be taken out of service and the existing power line taken down. If not, and no other cost-effect solutions are found, the line can be rebuilt as proposed.

Meanwhile, both the Public Advocate and CMP will look for future projects that meet the criteria for a possible non-wires alternative.

“We’re seeing multiple opportunities across our system,” said Charlotte Ancel, CMP’s vice president for regulatory matters.

Both parties also say that non-wires projects will complement a new law in Maine that requires utilities to undergo what’s called integrated grid planning. Seen as a climate-fighting tool, it’s meant to develop an electric grid that supports the transition to cleaner energy at the least cost to customers. The process will start this fall at the PUC.

“Think of it as thousands of smaller resources,” Ancel said, “choreographed for different conditions. When the sun’s shining, when the wind’s blowing, in July at 4 p.m. with the air conditioning on. All these processes are going to converge. That’s where we’re going.”

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