This story was originally published by Lisa Prevost in Energy News Network.
Green Mountain Power’s new “resiliency zone” initiative is using outage and other data to pinpoint places in need of local grid upgrades. Its first projects consist of microgrids that will power remote villages during outages.
Tropical Storm Irene caused widespread devastation when it roared into Vermont in the summer of 2011. And few communities fared worse than the remote mountain town of Rochester.
Tucked between the two main ranges of the Green Mountains, Rochester was cut off in every direction for days after flood waters destroyed access roads and other infrastructure. The town’s 1,000-or-so residents, stuck on what had essentially become an island, had no power, internet or phone service.
“People had to queue up in front of the grocery store and be escorted in with flashlights,” recalled Jeffrey Gephart, the town’s energy coordinator. “And somebody had to round up a pump and generator, cordon off the gas station and pump people their 5- or 10-gallon allotment.”
Such extremes promise to get worse in the face of climate change, especially for a town that, because of its valley location, is especially prone to “significant weather,” Gephart said. With that in mind, the local utility, Green Mountain Power, is building a microgrid that will power the central village during outages.
“When the village has an interruption, the system will act like an emergency generator,” Gephart said. So for residents in more rural locations who are also without power, “there will be access to food and some electricity there.”
The project is part of Green Mountain Power’s new “resiliency zone” initiative, aimed at making the electric grid more durable in some of the state’s most vulnerable communities. The utility will do three or four projects a year to start, “but we will eventually accelerate that schedule given the pace of climate change,” said Kristin Carlson, vice president for strategy and external relations.
The testing ground for the program was the western Vermont town of Panton, a rural community of about 700 residents on Lake Champlain. Green Mountain Power spent several years working out the complexities of setting up a microgrid there powered by a 5-megawatt solar array and a 4-megawatt battery system. In operation for about a year now, the microgrid covers 62 customers, including some town offices, homes, businesses and small farms.
The town hasn’t yet experienced a storm severe enough to cause the microgrid to kick in. But there are benefits that accrue to the broader grid nonetheless — the utility can tap the microgrid’s stored solar power during peak periods, when energy prices are higher, in order to lower costs for all utility customers.
“We are thinking differently about resiliency, as a two-way system,” Carlson said. “It’s a constant sharing and balancing and flowing.”
The Panton microgrid is believed to be the first in the country to be backed up solely by renewable energy, and not by fossil fuels.
“It was a couple of years of engineering work,” said Josh Castonguay, vice president of engineering and innovation. “We kept solving one problem after another, and finally got to the point of getting this fully functioning microgrid. Now, we are carrying all that stuff forward.”
The utility, which serves about 270,000 residential and business customers, is pinpointing the communities most in need of resiliency zones by looking at outage data, broadband availability, and CDC vulnerability data. The communities receiving the first round of microgrids — each of which will be customized to meet local needs — are Rochester, Brattleboro and Grafton.
In planning the microgrids, the utility carefully considers which types of customers make the most sense to cover, Castonguay said. The size of the microgrid has to be limited by definition, “as the bigger you make it, the more things can go wrong, which is what you’re trying to protect against.”
The microgrid in Rochester will look much like the one in Panton, only not as big. The solar array and the battery will each have a 1 MW capacity. The solar array will be sited on an abandoned gravel pit close to the village, and the panels will be elevated high enough to allow cattle from a local organic farm to graze underneath, Gephart said.
In Grafton, a village in southern Vermont, the focus is on about 60 residents who live “up in the woods” and experience a higher number of outages and poor cellular connectivity, Castonguay said. The approach there is to provide the residents with home battery storage devices as a backup source.
As it has done for several years through a separate home battery leasing program, the utility will draw on those batteries when they are not needed by the homeowners.
“We’ve built up a lot of knowledge as to how to leverage these batteries,” Castonguay said.
In Brattleboro, a former mill town in the Connecticut River valley bordering New Hampshire, the utility is targeting about 200 manufactured homes that are part of the Tri-Park Cooperative Housing Corporation, the largest manufactured home community in the state and a major source of affordable housing.
The Whetstone Brook, a tributary of the Connecticut River, flows through town and once powered the mills. But it is also a source of flooding, and during Irene, “it took out a huge swath of manufactured homes,” said Stephen Dotson, Brattleboro’s sustainability coordinator. “We really saw we had to change how resilient we were in a number of ways. With flood mitigation, of course, but also to deal with power outages.”
Many Tri-Park members are elderly, and/or without family support, transportation or cell phones, said Kay Curtis, a former board member who said she expressed her concern about these residents to town and utility officials.
“I was concerned about them losing power and not having the resources to leave or protect themselves,” Curtis said in an email exchange. “Some are unable to navigate the steps to leave their homes. I personally visited an elderly resident during a power outage and told her not to leave her bed until the power came back on. The temperature in her home had dipped to 40 degrees.”
Green Mountain Power approached the town about a resiliency zone, and has since negotiated an easement with the cooperative that will allow them to install a battery storage unit that will kick in if the power goes out.
The $50,000 lease payment for the easement will go into a fund to help residents make their homes more energy efficient.
The section of the cooperative the microgrid will serve, called Mountain Home Park, has been subject to periodic flooding for decades, said Mary Houghton, a board member. The cooperative is working on a major redevelopment plan that includes the relocation of homes that are situated directly in the floodway. But it’s an expensive proposition that will take time, she said.
“The goal is to provide people with assistance and make it as easy as possible to move,” Houghton said. “It’s a very pretty location by a stream, and it’s lovely until it floods.”