Nantucket Gets Largest Back-Up Energy Source in New England

Back up generator helps make the island more resilient, defers need for new transmission

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National Grid launched one of the largest battery energy storage resources in the Northeast United States. Built on the island of Nantucket, Mass., the facility will ensure electric reliability for customers during peak summer months and defer the need for construction of an additional underwater supply cable to the island.

To meet Nantucket’s rapidly growing demand, National Grid developed an integrated plan, IslandReady, to upgrade the island’s electricity infrastructure. A critical component of this plan entailed the development and construction of a 6 MW/48 MWh battery energy storage system (BESS), the largest of its kind in New England. The BESS was built by Tesla. In addition, a new 15 MW generator and power control house was installed. The project cost approximately $81 million.

“Both energy storage and a back-up generator are vital components to ensuring resilience and reliability on Nantucket during the busiest summer months,” said Rudy Wynter, president and COO of National Grid’s Wholesale Networks and US Capital Delivery group.  “Battery storage is key to unlocking the state’s and the island’s clean energy future.  We are pleased to now operate the largest battery facility in New England to ensure that Nantucket has safe, reliable power.”

The BESS, combined with the new, upgraded 15 MW diesel generator, has the capacity to supply the island with energy during peak summer months if one of the two underwater cables currently serving Nantucket experienced an outage. The BESS has a 48 MWh capacity, meaning it can provide 6 MW of capacity for up to eight hours. 

“Energy storage projects like National Grid’s Battery Energy Storage System are a critical part of unlocking the full potential of clean energy and increasing the resiliency of the electrical grid,” said Department of Energy Resources Commissioner Judith Judson. “The Baker-Polito Administration is committed to working with utilities to expand energy storage throughout the Commonwealth to deliver ratepayers with the financial and environmental benefits associated with the technology.”

The demand for electricity on Nantucket — particularly during the busy summer season — has grown significantly in just the last 10 years, from 37 MW in 2008 to nearly 49 MW in 2018. Nantucket has approximately 11,000 year-round residents, and the population swells to more than 50,000 during peak summer months. The energy demand growth is projected to grow for the foreseeable future.  Nantucket receives its power from two undersea transmission supply cables roughly 30 miles in length connected to the mainland, which were installed in 1989 and 2005.

National Grid plans its network to ensure reliability. The BESS and back-up generator will serve to maintain electricity supply in case of cable failure. This project ensures that there is adequate back-up supply on the island for the years to come, ensuring reliability, and saving customers’ money. 

“This project is helping Nantucket and the state meet energy policy goals,” Wynter said.  “We’re proud to support a project that works toward a cleaner energy future.”

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