Eversource’s Framingham Geothermal Pilot Project Nearly Ready, on Schedule

By Eric Weld, MassLandlords, Inc.

Eversource is nearing the point at which it will flip the ON switch for its groundbreaking, regionally networked geothermal pilot project in Framingham. Once the pilot is operational, the utility will monitor its efficiency, cost and customer satisfaction over the course of two heating and cooling seasons to determine levels of success and next steps.

This borehole drill prepares to drill one of 90 holes in Framingham’s Concord Street neighborhood, where a network of pipes will be installed as part of the geothermal pilot project. Image: Eversource source photo.

In spring 2022, Eversource, New England’s largest electricity and natural gas utility, raised the bar in the global campaign to transition from fossil fuel combustion to more efficient energy sources. The utility announced a neighborhood-wide, networked geothermal pilot project on and around Concord Street, a mixed-use block near the center of the metrowest city.

The pilot is the first geothermal project of its kind in the nation, servicing a broad mix of building usages. It will serve 37 buildings in the neighborhood, a blend of 140 residential, commercial, educational and municipal customers who will receive their heating and cooling energy from a single closed underground loop.

While geothermal energy has been around for a long time, residential systems have until now mostly been installed one at a time, and at high upfront cost to the property owners. Also, some other multi-building geothermal projects are either in the works or already operational, many on college campuses, but none supply energy to such a range of customers.

The Concord Street neighborhood was chosen for the pilot partly because of its mixed use. In many ways, the neighborhood exemplifies the typical profile of mid-city utility customers: not only different building uses, but also diverse income levels and a mix of energy systems being used. If an energy transition could work en masse in this pilot project, it would bode well for its success in thousands of similar settings throughout the country.

Geothermal the Most Efficient Energy

Geothermal energy may be the future. It is the most efficient form of energy available because it derives heat from underneath the earth’s surface, where the temperature naturally remains a constant 50 to 60 degrees Fahrenheit year-round. In warm summer seasons, heat is drawn from buildings’ interiors, creating a cooling effect, and distributed underground.

Geothermal systems use less electricity than traditional HVAC because no energy is necessary to heat or cool air. Only the systems’ pumps, fans and compressors use electricity. Between one third and a quarter of energy used for heating and cooling in a geothermal system comes from electricity.

A Shared Energy Network

The Framingham project is installing a series of pipes in a large loop branching from Concord Street along Normandy Road and Berkshire Road. The system includes a horizontal main pipe traveling the distance of the large neighborhood loop, interspersed with vertical loops that jut 600 feet beneath the earth’s surface. A viscous liquid (called propylene glycol) will constantly course through the pipes. The liquid is naturally warmed by the underground temperature. The warmed liquid travels back up into the main and enters periodic horizontal service lines into buildings along the route, each equipped with ground source heat pumps (GSHPs) that convert the thermal energy into heat for warming their interiors.

In cooling mode, the coursing liquid will draw warm air out of building interiors, cooling their spaces, and transport it underground, where it is distributed before recirculating again.

The constant underground temperature is a key to the geothermal system’s efficiency. When surface temperatures are cold, the glycol draws heat from deep underground and transports it into buildings above. When the surface temperature is warm, the glycol disburses heat absorbed from above-ground buildings deep underground.

A Potential Model for the Future

The Eversource geothermal pilot has been approved by the state Department of Public Utilities to explore whether a large, networked geothermal system could be a cost-effective way to replace combustion systems like heating oil, natural gas or propane.

We already know that geothermal energy saves cost at the level of individual homes and businesses. Once operational, geothermal systems have been shown to save up to 70% per year on energy bills. The large cost of geothermal is stacked upfront, in the excavation and drilling for pipe network installation, and ductwork in building interiors, if needed. For this project, those costs are being covered by Eversource, so that participating customers will only reap the savings of an operational system.

Eversource is investing more than $10 million in the Framingham project, part of which will cover construction and installation, along with equipment in customers’ buildings. Local participation is voluntary among customers in buildings located along the loop route. Participating customers agree to pay a fixed monthly charge for their geothermal heating and cooling service, and provide feedback to Eversource. If the project is successful and geothermal service continues, customers’ gas – or other combustion source – bill would be replaced with a glycol bill, or equivalent.

A main objective of the Framingham pilot is to discover if the savings and efficiency of a geothermal energy system can be realized at utility scale.

“Over the course of the next two heating and cooling seasons, we will gather data on efficiency, cost, greenhouse gas reduction, and customer satisfaction – among other metrics – to help us determine next steps,” Chris McKinnon, an Eversource spokesperson, told MassLandlords.

If the Framingham project is determined successful after two heating and cooling seasons, Eversource would seek approvals for additional systems and a possible expansion of the Concord Street loop, McKinnon said.

If it is deemed successful, the Framingham project would also potentially pave the way for other utilities and companies to install similar regionally networked geothermal systems that could enormously boost global efforts to achieve zero fossil fuel combustion emissions.

Start Date: November 2023

Eversource plans to place the entire loop into service at the same time, said McKinnon, sometime in November. The utility is drilling some 90 boreholes for the main and deep underground pipes, as well as a pump house along the route of the loop. It is also working with customers to install GSHPs in each participating building, as well as any necessary ductwork and energy efficiency upgrades needed to accommodate geothermal.

Other similar interconnecting geothermal projects are in various planning stages elsewhere in the country, including one announced by National Grid. With its operational status planned for November, Eversource’s Framingham pilot will be the first to go live and start collecting data.