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Martha's Vineyard switches to electric buses with solar and battery backup

The Vineyard's bus fleet is half electric, with a resilient, clean power source sited at the depot.

Julian Spector
Julian Spector
2 min read
Martha's Vineyard switches to electric buses with solar and battery backup

Martha’s Vineyard is joining the roster of islands that are building clean energy and electric transportation simultaneously.

The bus fleet at the seaside destination off the coast of Massachusetts will reach 50 percent electric in June, with a total of 16 e-buses. And the Vineyard Transit Authority has installed a solar and battery storage array on its own property to ensure continuity of service even if the island's grid goes down.

"An all-electric fleet of buses, vans, and service vehicles will ensure greater service reliability, lower maintenance and fuel costs, and create greater resilience when the power goes out. And we will be powering the buses from locally generated solar energy," VTA administrator Angie Gompert said at the unveiling of the microgrid May 14, according to The Vineyard Gazette.

Fuel security is top of mind for the East Coast after the Colonial Pipeline hack froze shipments of gasoline to the region earlier this month. Switching to electric vehicles eliminates risk from fuel price fluctuations and pipeline disruptions. But then a fleet’s resiliency depends on access to electricity.

VTA addressed that risk with 467 kilowatts (AC) of solar power and 1.5 megawatt-hours of battery storage, developed and installed by Borrego Solar. That effort received federal and state government grants to deliver resilient backup power. Then Enel X, the commercial energy subsidiary of the Italian energy giant, approached with an offer to get even more out of the battery.

"VTA is proving that [fleet electrification] works, it’s cheaper to operate, and there are ways to provide risk mitigation and revenue streams that were historically unavailable," said David Funk, senior manager for business development at Enel X, which now owns and operates the solar-battery facility.

In terms of risk mitigation, Enel owns the energy equipment, so VTA didn’t need to put a pile of cash on the line. VTA locked in a fixed rate for power produced over the next 20 years, which happens to be 30 percent cheaper than the cost of grid power on the island.

For additional revenue streams, Enel will bid the battery into demand response markets and enroll it in Massachusetts’ Clean Peak program, which rewards power plants that serve high-demand hours without emitting carbon. Enel and VTA will share the battery’s market revenue, which Enel believes will add up to $1 million over its operating life.

It's a convergence of mutually supportive emerging energy technologies. Solar alone would cease operating in a grid outage; batteries alone couldn't recharge in a blackout; electric buses without backup power would be vulnerable to the grid going down. Enel didn't build those items, but its control systems act as "that glue to bring these pieces together," said Philip Martin, vice president for energy storage at Enel X.

Islands are generally attractive markets for early clean-energy adoption. The geographical isolation gives distributed clean energy a competitive edge relative to connected mainland grids. For electric buses in particular, the limited distances make it easier to assuage range anxiety.

Martha's Vineyard has access to different sorts of resources than many other islands. And Massachusetts' policies to enact a low-carbon grid and support energy storage in particular helped deliver this outcome.

But the equipment will have to survive harsh nor'easters and frigid winters. Proving the concept in those conditions could help other islands decide to electrify, Funk noted.

Even outside of island contexts, customer conversations about solar and storage now often veer into vehicle electrification, Martin added.

(Article image courtesy of Enel X)

fleet electrificationelectric vehiclesSolarenergy storageEV chargingEnel X

Julian Spector

Julian reports on the rise of clean energy. He worked at Greentech Media for nearly five years, and before that he reported for CityLab at The Atlantic.