Eversource has received tentative approval by a Massachusetts siting board to build one of the first underground substations in the U.S.
The estimated $1.5 billion project, dubbed the Greater Cambridge Energy Program, calls for eight new 115 kV transmission lines housed in five underground duct banks, primarily below public roadways, linking the new substation to four existing substations located in Somerville, East Cambridge, Cambridgeport, and Brighton.
The substation site was identified in collaboration with the City of Cambridge, the Cambridge Redevelopment Authority, community stakeholders, and the developer of a large mixed-use project that includes the substation site. The Massachusetts Institute of Technology opposed the project in what the Cambridge Day newspaper called a “nasty” fight between the institution and utility.
In its decision to tentatively approve the project, Massachusetts Energy Facilities Siting Board said the project will allow Eversource to meet rapidly growing electricity demand in the area, which is being driven by new development and electrification efforts.
If formally approved by the siting board, Eversource expects to complete the substation and transmission line project in 2029. It is expected to include three 90 MVA 115/14 kV transformers, twenty-two 115 kV circuit breakers, six 115kV series inductors, six 14 kV, 9.6 MVAR capacitor banks and associated switchgear.
Eversource plans to build the substation in an underground vault located approximately 110 feet below the surface. The first underground substation in the U.S. was built by Anaheim Public Utilities in 2006.
