Massachusetts utility Eversource is commissioning what it calls a first-in-the-nation utility-led thermal energy network—a pilot project in the Boston suburb of Framingham that connects 24 single family homes, 100 city housing apartment units, some public structures and five commercial buildings to provide 135 total customers with heating and cooling from a renewable source.

Eversource said it will decide if utility-scale geothermal networks can “feasibly and affordably” be expanded or replicated in other “densely populated and mixed-use areas of New England” after it finishes analyzing the network’s performance during two heating and cooling seasons. The pilot will help determine if such a system can replace legacy energy sources—such as natural gas, air source heat pumps or delivered fuels such as heating oil and propane—or be used in tandem with existing heating and cooling systems.  

Customer conversions will continue through the summer as Eversource starts collecting data on the network in July. 

Auburn, Mass.-based R.H. White Construction served as the general contractor on the estimated $14-million project that broke ground in June 2023, while CDM Smith was design engineer of record.

Project challenges included “customer conversions and finding locations for system pumping assets," Daniel Flaherty, a mechanical engineer at CDM Smith, told ENR in an email. "With effective collaboration between Eversource, CDM Smith and the Framingham community, we've been able to handle those challenges and create a first-of-its-kind system that points the way to a clean energy future."

Each customer is connected to an approximately one-mile loop of pipes that uses the earth's consistent underground temperature to deliver heating and cooling.

"This is a highly complex project, connecting a diverse group of customers into a single geothermal pilot,” Flaherty said. 

The pilot was approved by the Massachusetts Dept. of Public Utilities in 2020 and involved collaboration among public, private and non-profit groups, including HEET—a national organization focused on the potential of a thermal energy transition.

“Massachusetts is on the cutting edge of leading an unprecedented clean energy transition in New England, and our networked geothermal pilot exemplifies the collaboration that is essential to achieving decarbonization goals,” Joe Nolan, Eversource chairman, president and CEO said in a statement. “Over the next two years, we look forward to closely evaluating how this technology can be cost-effectively leveraged in other communities as part of a comprehensive approach to combatting the climate crisis.”

Utility National Grid, which serves New York and Massachusetts, also has efforts underway to determine if a geothermal network can substitute for residential and commercial natural gas service. It launched in April a two-year Networked Geothermal Pilot Program demonstration in Lowell, Mass. to use Information gathered from the borehole drilling to inform design of a networked system.

Plans for a geothermal network, led by National Grid, are also underway in Boston.  In January, Boston Mayor Michelle Wu announced plans for the city’s first-ever utility networked geothermal system, also led by National Grid, to deliver renewable heating and cooling to 346 families in the Franklin Field affordable housing community in Boston's neighborhood of Dorchester.

The New York State Dept. of Public Service in April approved nine additional utility projects that could generate energy from renewable sources including geothermal boreholes, wastewater or surface water. 

Massachusetts and New York are among 13 states weighing benefits of geothermal energy through pilot projects or legislation to allow gas utilities to boost networked heating and cooling capabilities.