“The novel thing here is the utility coming in and deploying a system that connects up with a number of private individuals to a shared system,” said Eric Bosworth, manager of clean technologies at Eversource.

While a shared system has been utilized before on college campuses or in hospitals, this is the first time in the United States that a utility company has ever installed geothermal across a neighborhood.

“As an energy provider, we are always looking for ways to provide clean or decarbonized energy to our customers, and this is an option that seems to make a lot of sense,” Bosworth said.

The Framingham Project

HEET first approached Eversource with the concept of a network geothermal project around 2018. They presented to Eversource why it makes sense for utilities, where the skills overlap, and encouraged them to explore the idea. A lot of the installation and operations involved in network geothermal loops fit in very well with a utility company’s traditional skill set and traditional business model.

“So, as we talk about what the energy systems of the future are going to look like, it makes a lot of sense to explore something that is kind of a natural translation of what we already do day-to-day; the only difference is we're moving water through the neighborhood at a zero-carbon system versus some of our traditional utility offerings,” Bosworth said.

Audrey Schulman, co-founder of HEET and executive director of the recently formed HEET spinoff, HEETlabs, told Inside Climate News that the commissioning of the project in June of 2024 was a dream come true, and a greater impact than she could’ve ever imagined.

“It was a joint effort between [HEET] and ourselves to talk about the technology, come up with a concept that may work, which we ultimately then present it back to the department,” Bosworth said. “And they're not the only ones, certainly from a stakeholder standpoint, that have been involved in this project. It was a great collaboration between ourselves, folks in the geothermal industry, advocacy groups, and stakeholders — even groups like the MassCEC have been critical to the success of projects like this.”

Approved by the Massachusetts Department of Public Utilities in 2020, the $14 million Framingham project broke ground in 2023 and connects five commercial buildings and 31 residential homes through one geothermal system.

“At a very high level, it is a one-mile shared pipe that runs throughout the neighborhood in Framingham, Massachusetts,” Bosworth said. “It connects approximately 135 individual customers to this shared loop. To give you an idea of overall scope, it's about 375 tons of peak heating or cooling load, depending on the season.”

The thermal energy that feeds this network comes from approximately 94 holes drilled 600-700 feet underground.

“These types of projects are key to advancing electrification and decarbonization,” said Gage Foley, sales engineer at APA HVAC Technologies, one of AAON/BASX’s rep companies who supplied the AAON products to the Framingham project. “By using geothermal heat pumps, it allows Eversource to analyze the technology in reference to other low-carbon options, offering insights for future projects. Projects like this help pave the way for cleaner HVAC solutions and progress in the industry.”

The Install

Eversource went with one of their standard MSA gas contractors for the job, R.H. White Construction in Auburn, Massachusetts. The company does many, many miles of gas pipe replacement for Eversource every year, and they acted as the general contractor on the project.

FUTURE OF GEOTHERMAL: If more utility companies follow Eversource’s suit, decarbonization goals could be reached that much quicker. (Courtesy of Eversource)

R.H. White had never done geothermal drilling before, so any work that was not a day-to-day activity for the construction company like drilling work or home and building conversion work, was subcontracted out.

When it came to deciding what type of equipment would be installed, the majority of it is just HDPE pipe, the exact same resin that would be used in a water or gas system.

“Where possible, we used American-made products to comply with the domestic content requirements for federal tax incentives,” Bosworth said.

All of the HDPE pipe generally came from the same vendor, Centennial Plastics, and it was readily available. Some of the other equipment used in the project included Bell & Gossett circulating pumps and heat exchangers. The heat pumps used were from various manufacturers including Samsung, WaterFurnace, and AAON.

What manufacturers were used depended on which building within the Framingham project they’d be installed in and how the application looked.

“In most cases, we were using one vendor of heat pump,” Bosworth said. In other circumstances that required, for example, the install a very specific niche split system, they then used a different manufacturer of heat pumps. The commercial units came from a third heat pump vendor.

AAON in particular provided four RN Series water-source heat pump (WSHP) rooftop units.

“These units came equipped with digital scroll compressors for the lead stage and two-stage compressors for the lag stage, where applicable,” Foley, sales engineer at APA HVAC Technologies, one of AAON/BASX’s rep companies who supplied the AAON products to the Framingham project. “The units were provided with backup SCR electric heat. For mounting, systems were provided with adapter curbs or spring isolation roof curbs.”

Deciding on what products AAON provided was driven by the pilot initiative which is the Framingham project.

“They required high efficiency, compact, WSHP rooftop systems, for a range of applications that could be used for retrofitting the existing building,” said Foley. “The AAON units fit perfectly, with modulating, high-efficiency compressors, WSHP capability, and small footprint.”

These products offered a high-quality, cost-effective geothermal WSHP.

“As a pilot project, this allows Eversource to study the efficiency of a geothermal retrofit, helping to guide decarbonization projects in the future,” Foley said.

Since AAON provided package rooftop systems, they were quick to install.

“Due to a request for early startup, we were able to provide a ‘pre-startup’ to get the systems running while they wrapped up the final requirements prior to startup,” Foley said.

Challenges

Like with any project of this scale, there are bound to be a few hiccups along the way.

According to Bosworth, the project saw the standard challenges that come with any large construction project when the neighborhood is being disrupted by pipes being installed in the street or the opening and closing of roads. Then, of course, there were challenges with the supply chain and lead time — not to mention the initial proposal and budget were approved pre-COVID, and construction began post.

“You can imagine what that was like in terms of timelines and cost,” Bosworth said. “But in addition to that, I think one of the unique things to network geothermal is specifically this application.”

That’s because the vendor ecosystem is not as built out as some traditional offerings. So, Bosworth said, things like drilling services may be limited in area, especially as geothermal technology continues to grow in popularity.

There are only so many spaces to drill.

“There's going to be some time for the companies that actually perform the drilling to ramp up workforce, ramp up equipment, and really be able to deploy these on the utility scale,” Bosworth said.