Eversource Breaks Ground on Largest U.S. Underground Substation

Executives from Eversource and their partners break ground on the Greater Cambridge Energy Program substation project in January. (Photo: Eversource)

In late January, Eversource broke ground on a $1.8-billion project in Cambridge, Mass., that, upon completion, will include the largest underground electrical substation in the United States.

The Greater Cambridge Energy Program substation will occupy 35,000 square feet and feature eight new 115-kilovolt transmission lines, which will span more than 8 miles and power portions of Cambridge, Boston, Somerville, and surrounding communities. The facility will be more than 100 feet underground at the site of a former parking garage and underneath what will be a new public green space.

“By taking a collaborative approach with the community and local leaders, this critical energy infrastructure meets several needs for our customers and the region’s energy supply while helping to enable the clean energy transition,” said Eversource Chairman, President, and CEO Joe Nolan.

By placing the facility underground, Eversource hopes to minimize its footprint within the city while enhancing grid resilience and insulating lines from above-ground threats such as extreme weather. Eversource has spent years designing the facility and conducting community engagement efforts with customers, local leaders, and other stakeholders, having started public outreach efforts in 2019. The company has since partnered with the city of Cambridge, the Cambridge Redevelopment Authority, and real estate investment company BXP to bring the project to life.

“This region is experiencing a surge of new residential and commercial development, while at the same time moving away from fossil fuels. This generates a growing demand for a reliable electrical grid,” said Cambridge City Manager Yi-An Huang. “The Greater Cambridge Energy Program helps address the increased energy needs in the region, enhance the resiliency and reliability of the grid to reliably serve customers in our community, and support the decarbonization goals of both Cambridge and the Commonwealth.”

Eversource designed the substation to help meet the needs of customers now and in the future, particularly as the economy continues to electrify. For example, the company estimates that the substation will allow it to handle all of its East Cambridge residential customers who are converting their traditional heating systems to electric heat pumps while cutting the area’s reliance on natural gas in half.

“The Greater Cambridge Energy Program is a creative solution that helps shape a more sustainable and resilient energy future for our customers,” said Nolan.

The undergrounding of substations is not a new concept in the United States, with the first such project opening in Anaheim, Calif., in 2006. Upon its completion, the Cambridge substation will be more than twice the size of the underground substation in Anaheim.

Eversource anticipates that it will be able to operate at least some of the facility by 2029 and that it will be fully operational by 2031, creating and supporting an estimated 500 full-time jobs.