Energy Storage Delivers Back-Up Power in Vermont

When a major rain and wind storm knocked out power supplies for 115,000 Vermont households on Hallowe’en, the 1,100 Green Mountain Power customers participating in a home battery pilot project did just fine.

The homes had their batteries in place “thanks to pilot programs specifically designed to promote resilient backup power with energy storage,” Greentech Media reports. “The battery backup service lasted nine hours on average, but the longest instance stretched to 82 hours.”

When it launched its Grid Transformation Pilot a couple of years ago, Green Mountain (GMP) offered customers the option of paying a monthly fee to installs Tesla Powerwall batteries that would be owned and controlled by the utility. “The program previously generated more headlines by saving hundreds of thousands of dollars during annual system peak events,” including a single hour in 2018 when it cut the utility’s costs by nearly US$900,000, Greentech writes.

But the Hallowe’en power failure “offers a timely data point for other jurisdictions mulling the use of home batteries for resilience. Northern California community power purchasers…requested proposals for home batteries to keep customers powered during the region’s fire season safety shutoffs.” While “such a model remains cutting-edge,” Greentech adds, GMP “has shown it can be done effectively”.

“We think about our need to deliver reliability constantly,” said Chief Innovation Officer Josh Castonguay. “This has provided us with an amazing tool that can deliver reliability and also pay for itself.” As the grid decarbonizes and adapts to future climate risk, he sees residential storage becoming ever more important.

“I hope we get to a point where storage in a home is no different from a computer in a home,” he told Greentech.

A day after its account of the Vermont outage, Greentech was back with a report on the potential for electric vehicle batteries, working in tandem with photovoltaic solar arrays, to help households, businesses, and communities deal with forced power shutdowns.

“For much of any given day, EVs are parked in garages or at offices,” Greentech writes. “When paired with a power control system, the battery packs in those EVs are functionally little different than a stationary battery system.”

But “one big difference: EV battery packs are much larger,” often in the range of 40 to 65 kilowatt-hours, or up 100 kWh in some Tesla models. “By comparison, Tesla’s Powerwall home battery has a 13.5-kilowatt-hour nameplate capacity.”

If California is looking for guidance on how an emergency backup system might work, Greentech says officials should look no farther than Japan, where EVs have been supplying power to critical facilities in disaster zones for nearly a decade.

“Medical professionals at an evacuation centre were the first ones who approached us about possibly using them as backup batteries for heating and other purposes,” said Ryusuke Hayashi, senior manager of EV operations at Nissan, which supplied 66 first-generation Leaf electric vehicles following the Tohoku earthquake and tsunami on the country’s northeastern coast in 2011. “That experience triggered Nissan to accelerate development that enables EVs to share the energy stored in their batteries with homes, buildings, and communities.”

Greentech traces the early development of vehicle-to-home (V2H) platforms that connect EVs with local power systems. “Initially, what it’s going to offer is really an unparalleled resilience for homeowners and small businesses to be able to keep their homes powered through grid outages,” said John Sarter of Montreal-based start-up Ossiaco, which plans to enter the California market in March 2020.