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The recent cancellation of a Massachusetts networked geothermal project isn’t dampening enthusiasm for the emerging clean-heat strategy.
National Grid said this month it has abandoned a planned geothermal system in Lowell, Massachusetts, due to higher-than-expected costs. The news disappointed advocates who see networked geothermal as an important tool for transitioning from natural gas heat, but they pointed to many more reasons for optimism about the concept’s momentum.
The nation’s first utility-operated neighborhood geothermal network, a loop serving 36 buildings in the Massachusetts city of Framingham, is performing well and seeking to expand. It’ll soon be joined by a surge of pilot projects being developed across the country, testing different models and accelerating the learning curve. And a recent report forecasts as much as $5.2 billion in potential savings from leaning more heavily on geothermal energy than on air-source heat pumps.
“This is very promising,” said Ania Camargo, associate director of thermal networks for the Building Decarbonization Coalition. “Networked geothermal makes a lot of sense as a transition strategy.”
The idea for utility-operated networked geothermal systems, often also referred to as thermal energy networks, originated in Massachusetts. The concept grew out of conversations about the environmental and public health dangers posed by aging and increasingly leaky natural gas pipes.
In 2014, the state passed a law requiring gas companies to create plans to replace these leaky pipelines. These plans, however, are projected to cost nearly $42 billion to execute. Climate advocates began to question the wisdom of investing so much money in fossil fuel infrastructure when state policy was simultaneously pushing for electrification and renewable energy. At the same time, air-source heat pumps were catching on, a growing trend that would leave fewer and fewer gas consumers to foot the bill for pipeline repairs.
In 2017, Massachusetts clean energy transition nonprofit HEET proposed a solution: networked geothermal. The systems would be based on well-established geothermal technology, which circulates liquid through pipes that run deep into the ground, extracting thermal energy from the earth and carrying the heat back up to warm buildings. The same principle can provide cooling as well, transporting heat away from buildings and returning it to the ground.
Thermal energy networks scale up the process, connecting many buildings to one geothermal loop, allowing heating and cooling to be delivered to homes in much the same way gas and electricity are. At the same time, they offer a new business model for gas utilities grappling with states’ efforts to transition away from fossil fuels. Utilities liked the idea and jumped on board.
In 2023, the first two such systems broke ground in Massachusetts: National Grid launched one in Lowell, and Eversource began work on a system in Framingham.
The University of Massachusetts Lowell, which was a partner in National Grid’s now-canceled project, hopes to use the engineering and design work developed for the project as the basis for a future network, said Ruairi O’Mahony, senior executive director of the university’s Rist Institute for Sustainability and Energy.
Even the cancellation provides valuable insight by providing a case study of what didn’t work, said Audrey Schulman, executive director of HEETlabs, a climate solutions incubator that spun off from HEET. In this case, the problems included participating homes spread too far from each other and issues with the field where the boreholes were to be drilled. “We’re on an even better arc,” Schulman said. “If there’s a mistake made, we have to correct for it. We can’t have people paying for things that cost too much.”
Meanwhile, the Framingham network began hooking up its first customers in August 2024 and now has about 95% of its anticipated load up and running, said Eric Bosworth, clean technologies manager for Eversource. The system is performing well, keeping customers warm even when a recent cold snap dropped temperatures down to 6 degrees Fahrenheit, he said.
Plans are already underway to expand the system. The U.S. Department of Energy in December awarded Eversource, the city of Framingham, and HEET a $7.8 million grant to develop a second geothermal loop to be connected to the first network, in the process generating valuable information about expanding and interconnecting geothermal systems. The grant is still under negotiation with the federal agency, so it is unclear what the final terms will be. Still, Eversource hopes to have the second system installed in 2026.
“What we’re trying to prove out with Framingham 2.0 is, as we expand on an existing system, that we can do it more efficiently and bring down that cost per customer,” Bosworth said.
The widespread interest in networked geothermal systems within Massachusetts and throughout the U.S. is also promising, Camargo said. In Massachusetts, National Grid is continuing work on a different geothermal network pilot serving seven multifamily public housing buildings in the Boston neighborhood of Dorchester. Last year, HEET, with support from the Massachusetts Clean Energy Center, awarded $450,000 in grants to 13 communities to conduct geothermal feasibility studies. And a climate law passed in Massachusetts last year authorizes utilities to undertake networked geothermal projects without getting specific regulatory approval to veer out of their natural-gas lane.
New York has also embraced the idea with enthusiasm. In 2022, the state enacted a law allowing utilities to develop geothermal networks and requiring regulators to come up with guidelines for these new systems. So far, 11 projects have been proposed using a variety of approaches that will provide takeaways for the developers of future geothermal networks, Camargo said.
“New York is amazing,” she said. “They’re doing things in different ways to innovate.”
Across the country, between 22 and 27 geothermal networks have been proposed to utility commissions in Colorado, Maryland, Minnesota, and other states, she said. Eight states have passed legislation supporting utility construction of thermal energy networks, according to Building Decarbonization Coalition numbers, and another four or five are expected to file bills this year, Camargo said.
A report prepared by Synapse Energy Economics for HEETlabs and released last month concludes that geothermal networks offer significant financial benefits when compared with using air-source heat pumps. The analysis found that each system roughly the size of the Framingham network could generate from $1.5 million to $3.5 million in economic benefits, including avoided transmission and distribution costs from lowering peak demand. If 1,500 geothermal networks came online in Massachusetts, the savings could hit $5.2 billion, the analysis calculates.
These savings could be used to subsidize building retrofits, making the homes and offices connected to a geothermal network highly energy efficient to optimize the impact of the ground-source heat pumps, Schulman said.
Even with gathering momentum, challenges remain to the widespread adoption of geothermal networks.
Retrofitting buildings on the network is perhaps the thorniest, particularly in the Northeast where much of the building stock is older and draftier, said both utilities and advocates. In Framingham, an individual efficiency plan had to be created for each home and structure on the loop, a time- and money-consuming process. Going forward, a more streamlined, standardized procedure will likely be necessary, Camargo and Bosworth both said.
“Utilities have not traditionally worked inside the building, so who does it and who pays for it is something that still needs to get worked out,” Camargo said.
Cost is another concern, as the terminated Lowell project demonstrates. However, costs are likely to come down as engineers and installers gain experience in the process and develop smoother supply chains, Schulman said. The second loop planned for Framingham is already likely to be half the amount of the initial system, she said.
As these challenges are worked through, it is vital for Massachusetts to approach its role as a leader in geothermal networks with care, Schulman said.
“We need to think ahead and do this in an efficient and thoughtful way and show the country how it can be done,” she said.
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