Eversource Gas breaks ground on first networked geothermal installation

November 23, 2022

Framingham, Massachusetts is the site of the first gas-utility-run networked geothermal system, ever! Once complete, this network of water-filled pipes, heat pumps and boreholes will provide heating and cooling to a community of over 40 houses, apartments, and commercial buildings, including low-income housing.

How did we get here? 

HEET first pitched the idea of networked geothermal as a clean heat business model to gas utilities in winter of 2017. Then, along with Buro Happold Engineering, we launched a technical and economic feasibility study to determine how well networked geothermal could work in Massachusetts and how much it would cost. 

Thanks to the study’s exciting results, in 2019, Eversource Gas filed a request to build three geothermal networks in Massachusetts. The next year, the Department of Public Utilities granted Eversource approval to build one of those installations. 

Each step along the way has been a first and has required careful consideration (time!) from the Department of Public Utilities, from Eversource, and from the host city and participants. The site selection process itself had the excellent challenge of many sites vying to be chosen. For those interested in becoming the site of a future network, add your name here

A Growing Network of Interest

HEET is in conversation with gas utilities, municipalities, and others across the country, all interested in the potential of networked geothermal (Minnesota, Vermont, DC, Philadelphia and more). National Grid is announcing the first of four upcoming geothermal networks before the end of the year. The model has even gained the support of some gas worker unions such as the pipefitters.  

Why? Networked geothermal offers utilities a business model to phase out natural gas, while workers get to apply their skills to green technology, and the public gets non-combusting, healthier, safer and affordable heating and cooling.

Research Team

In preparation for utility-run systems like the one in Framingham to become a reality, HEET has convened top scientists and experts from across the country to evaluate networked geothermal as a viable pathway to zero-emissions heating and cooling. Massachusetts Clean Energy Center awarded HEET a $5 million grant for the multi-year research effort called ‘Learning from the Ground Up’, or LeGUp. Participating institutions include Boston University, MIT, Salem State University, University of California Berkeley, National Renewable Energy Laboratory and Lawrence Berkeley National Laboratory. 

Test Boreholes 

The first step in the Framingham networked geothermal installation was to drill three test boreholes for heat exchange. The holes go 600 feet down in the ground and contain a loop of pipe filled with water. Water picks up the temperature of the earth (about 55 degrees Fahrenheit all year here in Massachusetts). Water will then be piped to buildings, where a heat pump will transfer heat inside the building or pull heat back into the water, raising or lowering the indoor temperature.  

Measuring Temperature with Fiber Optic Cables 

Researchers Sumeet Sinha and Yaobin Yang attach a fiber optic cable to the water pipe.
The moment we got data back from 600 ft below ground!

Members of our LeGUp research team from UC Berkeley attached a fiber optic cable, or a wire that senses temperature, to the pipes in each borehole. This data gives us a more accurate understanding of the conductivity of the bedrock to help inform Eversource’s design.

The Result

This is what we’re getting excited about? A pipe sticking out of a pile of dirt? That’s right! When complete, you won’t even see this pipe stub. 

As our research team lead Asha said, “All the exciting stuff is happening underground.” But actually, a lot of exciting stuff happened above ground, too.  

What’s Next? 

Eversource will use the data from the test boreholes to finalize their design and then begin the construction phase, drilling more boreholes, laying pipes in the street and connecting them to local buildings.  

We’re excited to continue gathering data as more networked geothermal projects move forward throughout the state and use what is learned to optimize this technology for a wider scale transition from gas to geo. We’ll be sure to keep you updated on our data collection and analysis!