14-02-2025
Massive battery energy-storage facility proposed in Killingly
Killingly — At the site of the scrapped Killingly Energy Center fossil fuel plant, a proposed $400 million battery energy-storage facility would house the state's largest reserve of clean energy, but residents' concerns over potential fire risks and technical roadblocks threaten its development.
The Windham Energy Center, owned by the Israel-based company Sunflower Sustainable Investments, would sit on roughly 20 acres of a 63-acre parcel at 189 Lake Road. According to project documents prepared for the Connecticut Siting Council, construction is expected to take about 14 months.
Jonathan Milley, a spokesperson for the Windham Energy Center, described the facility as 'exactly the kind of asset that Connecticut needs' if the state wants 'to try to maintain the lowest energy costs possible.'
Milley explained the site is positioned at the intersection of nuclear and offshore-wind transmission lines from the Millstone Nuclear Power Station and Brayton Point Renewable Energy Center.
'The way the New England grid operates, this project will be incentivized to purchase its energy when the prices are the lowest and discharge it when the prices are otherwise the highest,' Milley said, adding that the energy dispatched from the facility will replace higher-cost energy, lowering prices.
With a capacity of 325 megawatts, the proposed energy center would dwarf all other pending and approved battery energy-storage projects in the state. The Connecticut Siting Council has permitted just nine such facilities since 2023. The power capacities for those projects range from 4.9 megawatts to 18.
According to Milley, the Windham Energy Center could power 325,000 homes — more than 20% of the state's housing stock — for 2 hours. Milley said this capacity is sufficient to mitigate peak-period demand when energy costs are at their highest.
In 2021, the General Assembly set a target deployment of 1,000 megawatts of energy storage in the state by Dec. 31, 2030. To date, the Connecticut Siting Council has approved roughly 60 megawatts of storage.
'This is exactly the kind of project that the state has made it clear that they want,' Milley said.
The state's energy-storage legislation was seen as a step toward achieving Connecticut's clean energy goals. Environmental advocates have championed battery technology as essential for storing and delivering energy from wind, solar and other energy sources, but the systems have faced criticism for their potential fire risk if batteries are damaged or overheat, a phenomenon known as thermal runaway.
Fire risk and prevention
Last month, a fire at an energy storage plant in Northern California burned for days when lithium-ion batteries at the 750-megawatt facility caught fire.
'That is one of the biggest concerns,' Killingly Town Council Chair Jason Anderson said. 'What happens if there is a fire, and what kind of containment is necessary to prevent any kind of pollution?'
Since 2012, the Electric Power Research Institute has documented 26 incidents in which battery energy-storage systems have failed in the U.S. A 2023 report from EPRI explained that systems may fail as a result of thermal runaway, 'leading to venting of flammable and/or toxic gases and the possibility of fire or explosion.'
Once these reactions start, EPRI said, they are difficult to extinguish and can 'reignite hours, days, or even weeks later.' As a result, the industry has adopted a ''let it burn' philosophy' to allow fires to 'burn out in a controlled manner while protecting adjacent exposures,' EPRI said.
While Milley said the Windham Energy Center would essentially follow the let-it-burn protocol, he explained that batteries for this project would use lithium iron phosphate technology, which is much less susceptible to thermal runaway.
'The chemistry differences between the type of battery that caught fire in California versus the type that the industry is now using and that would be used for this project is almost as stark as the difference between the diesel engine and a gasoline engine,' Milley said. 'The reason the industry has gone to this lithium iron phosphate chemistry is to not only mitigate but practically eliminate the possibility of this kind of catastrophic fire.'
Milley added that while the Windham Energy Center batteries may be safer, 'that doesn't mean that there is no risk of fire whatsoever.'
In addition to following all fire and electrical codes, including establishing emergency response plans, Milley said, all batteries would be monitored 24/7 from a remote operation center. If a unit shows signs of thermal runaway, staff would immediately shut down the battery for inspection, he said.
In the event of a fire, Milley said, the facility is designed to contain the fire within the failed unit, allowing it to burn out.
Killingly Fire Marshal Randy Burchard said that if people understood the level of regulation behind battery energy-storage facilities, 'they probably wouldn't be worried as much.'
'A lot of people get a misconception of a battery system versus a lithium-ion battery that's in your house or within your car. It's a totally different animal,' Burchard said.
He explained that early detection, ventilation and fire suppression are key with these systems.
'As long as you can get the early detection there, there's really not much after that,' Burchard said. 'It's a different type of firefighting, and it comes down to training the local departments nearby.'
While Killingly will host the facility, Anderson, the Town Council chair, explained that the siting council will make the 'ultimate decision on whether this project goes forward or not.'
He added his chief concern is ensuring the town can weigh in 'to get the best project possible for the town of Killingly.'
Anderson said he would like to have an independent expert evaluate the project and provide a better understanding of how the facility might impact ratepayers.
'There isn't anything comparable, anywhere in the state of Connecticut, to the size of this one,' Anderson said. 'I am definitely in favor of the town looking to hire an expert.'
