Green Mountain Power is working to install grid-scale energy storage facilities in Georgia, Springfield, Bethel, Middlebury, Bristol and Barre, almost doubling their storage capacity across the state.
New large battery storage facilities will provide 25 megawatts of energy storage, adding to an existing 30 megawatts the utility already maintains throughout Vermont, Green Mountain Power announced this week.
The batteries act like generators, providing a backup when the grid goes down due to, for example, the increasing number of extreme weather events in Vermont and around the globe.
They also kick in during periods of high energy usage, which lowers prices for ratepayers, according to Kristin Carlson, vice president of external affairs at the utility.
Without them, in times of high usage, Green Mountain Power has historically made one-time energy purchases from the regional grid, operated by ISO New England. Those purchases are more expensive and contain more fossil fuel sources, such as natural gas, than the company’s long-term purchasing contracts. Customers benefit from the savings when GMP can avoid these short-term purchases, Carlson said.
One battery storage facility is already running in Barre, and others are expected to come online in the next two years.
In July, during waves of intense heat when many Vermonters were likely staying indoors and using air conditioners, Green Mountain Power used its existing storage to avoid purchasing energy from the regional market. According to Carlson, battery storage saved the utility’s 270,000 ratepayers around $1.2 million.
“We didn’t have to ask customers to reduce power use during that time,” Carlson said. “They could use the energy they needed to stay comfortable and safe during the heat without limitations.”
The facilities could also expand the capacity for additional in-state renewable energy, according to Peter Sterling, executive director of Renewable Energy Vermont.
“Storage really is the technology that will unlock the opportunity for clean and local power,” Sterling said. “Until we have more energy storage, we can’t really maximize the amount of solar we’re able to generate.”
Sterling often hears an argument that renewable energy companies shouldn’t work to bring more solar online because Vermonters use most of their energy at night, when solar energy isn’t being locally produced.
“This completely flips that argument on its back,” he said. “The reason to keep deploying more renewable energy is, now we can store it and use it when the sun isn’t shining, so we don’t have to buy dirty power from the grid at night.”
Still, the storage facilities are “not a free lunch,” said Annette Smith, executive director of Vermonters for a Clean Environment.
She pointed to the tension taking place between the pressing need to address a changing climate and the environmental and human impacts in the U.S. and across the globe that come from mining materials for batteries, such as lithium.
Battery storage facilities also come with some risks, she said, referencing a large fire caused by a 182.5-megawatt facility in California earlier this month, which caused officials to tell some California residents to shelter in place. A battery storage facility also caught fire in Australia in July of 2021, caused by a coolant leak.
Smith would like to see utilities wait to deploy battery storage until emerging technology addresses the dangers and humanitarian concerns associated with lithium-ion batteries.
“Is this the right technology to be deploying on a large scale at this time? I don’t think it is, but I don’t think we’re far away from having better technologies,” she said.
Carlson said Green Mountain Power is taking appropriate safety measures and are monitoring the systems around the clock.
The utility plans to recycle the batteries at the end of their 10-20 year lifespan and reuse their components, Carlson said. In terms of equity, she said the energy savings from community battery storage projects may particularly benefit lower-income Vermonters.
“That sharing component of everyone benefiting is really critical to having a sustainable and equitable energy transformation,” she said.