Eversource details decade of upgrades for Cambridge grid, unveils underground substation timetable and AMI rollout

Eversource told the Cambridge Health and Environment Committee that projected electrification will shift system demand and requires both near‑term operational measures and longer‑lead capital projects, including an underground substation in Cambridge and phased transmission and distribution upgrades.

Jason Wright, community relations at Eversource, opened the utility presentation and introduced a team that included Juan Martinez, director of system planning, Sofia Zhang, lead data scientist, Rick Branca from project engagement and Catherine Hori from distribution engineering. Martinez said the Electric Sector Modernization Plan (ESMP) translates state greenhouse‑gas targets into capacity needs: “as you electrify the system, right, we churn from a summer peaking system basically to a winter peaking system,” he said, noting that the crossover is projected between about 2033 and 2035.

Forecasting and local drivers: Sofia Zhang described a two‑track forecasting process that blends ISO/Massachusetts clean‑energy pathways with bottom‑up customer inputs from developers and account executives. The utility reported that Metro Boston demand could grow roughly 20% over the next ten years, driven primarily by commercial development and lab load; Cambridge’s recent five‑year cumulative growth rate was reported to have edged down from about 34% to 32%.

Major projects and timelines: Eversource described near‑term measures and long‑term projects for Cambridge:

- Near term: installation of a third transformer at Somerville (2026–2027) to relieve Prospect Street Station; interim operational transfers on distribution circuits. - Long term: the Greater Cambridge Energy Program, an underground substation that Eversource says is the nation’s first fully underground substation and is designed with expansion capacity so additional transformers can be added if demand grows. Rick Branca described the station and connected transmission projects, and listed multi‑year schedules for related works such as replacement of high‑pressure fluid‑filled lines with cross‑linked polyethylene (start dates and in‑service dates were given for planning and permitting purposes).

Branca said the underground modernization work is staged, with planning and outreach continuing; he also said customers will not lose service during the swap from old to new lines when the new lines are placed in service and the existing lines are decommissioned.

Distribution and residential impacts: Catherine Hori explained how electrification changes on‑the‑ground infrastructure: pad‑mount transformers, larger street‑level equipment and, in dense areas, more equipment inside or adjacent to buildings. She said a typical single‑family home currently using about 700 kWh monthly could see demand roughly double to triple when heat pumps and electric vehicles are added — a driver of many needed distribution upgrades.

Advanced metering: Eversource said its advanced metering infrastructure (AMI) program began in January 2025. The utility will add network devices to poles in late 2025 and plans neighborhood meter replacements beginning mid‑2027. Eversource said AMI will enable near‑real‑time interval data, automatic outage reporting and virtual meter connect/disconnect capabilities, and will be used over time to target proactive upgrades.

Public concerns and council questions: public commenters and councilors pressed Eversource and city staff on transformer siting and lead times. Patrick Barrett, a property owner, asked bluntly: “Where do I put my transformers? Where do I put my switch gear?” Eversource acknowledged long lead times for certain equipment after pandemic supply‑chain disruptions but said lead times have improved and that the utility stocks commonly used transformer sizes and can reassign inventory. City and Eversource officials discussed permitting and land access; Eversource said access to space (municipal parcels, conduits, easements) and streamlined permitting or letters of municipal support would accelerate projects.

Gas‑electric coordination: residents asked whether gas‑main replacement programs lock in additional fossil‑fuel infrastructure. Eversource described integrated energy planning between its gas and electric functions and said it is running pilots looking at customer affordability and the choices customers make; staff emphasized that gas mains are also being replaced for safety and leakage reduction under current pipeline replacement programs.

Bottom line: Eversource presented a staged strategy that pairs short‑term operational measures with long‑lead capital projects to add substation and transmission capacity and modernize distribution. The projects span the late 2020s into the mid‑2030s; councilors and staff pressed for municipal collaboration on permitting, site access and community outreach.