CDM Smith Staff
Geothermal heat pumps generally require less electrical energy to provide the same heating and cooling as conventional HVAC systems. Why is that? Because they tap into the nearly limitless natural supply of energy right under our feet. The City of Framingham, Massachusetts, a suburb of Boston, is one of a growing number of communities tapping into this efficient and sustainable energy source. With support from CDM Smith, Eversource, has embarked on an ambitious pilot project to take that technology a step further.
Thermal energy systems are growing among large, private entities that need to deliver reliable energy across an entire campus of varied building types. With a network of distributed energy, the owner, like a university or hospital, can use energy-efficient technologies like geothermal and sewer heat recovery to better manage and improve delivery.
The success of these energy districts has led Eversource to ask the question: What if we expanded those systems to serve an entire neighborhood, or even a town?
Taking cues from successful European examples, Eversource is piloting the first utility thermal energy network (UTEN) in North America. The project is a first-of-its-kind engineering effort that will retrofit a portion of the community from natural gas and delivered fuels over to a geothermal heat pump network operating on an ambient temperature loop.
“This is a highly complex project, connecting a diverse group of customers into a single geothermal pilot.” ~ Dan Flaherty, PE
Eversource, in consultation with CDM Smith, selected a one-pipe ambient loop approximately one mile long with three borefield areas (one central borefield with two recharge areas). The advantage of the one-pipe ambient temperature loop approach is that it offers greater expandability in the future and is lower cost to install initially compared to its two-pipe alternative. The project includes a central pumping facility and will retrofit a school building, a firehouse, low-income housing units controlled by the Framingham Housing Authority, and approximately 30 single-family homes.
The successful implementation of a geothermal energy network relies on efficient planning and sophisticated modeling techniques, says Jacky Kinson, lead mechanical engineer for CDM Smith.
“We not only modeled the energy loads for the buildings connected right now, but we also modeled the buildings that the utility would connect to in the future.”
Once Framingham emerged as the top candidate, CDM Smith and Eversource began a public outreach campaign, lauded by Eversource as the most successful public outreach campaign they have ever held, based on the high frequency of engagement.
Participants will pay a low fixed charge each month for access to the highly efficient geothermal network and will be responsible for the electricity to power the heat pump. However, their monthly energy costs should ultimately decrease because they will no longer be primarily paying for natural gas or high-cost delivery of fuels to heat and cool their homes and businesses.
The pilot is intended to run through two heating and cooling seasons, with a planned loop consisting of 45 buildings, 30 of which are residential homes. At the end of 2025, Eversource received funding from the U.S. Department of Energy that will allow it to increase the project to twice its current size.
Learn more at https://www.cdmsmith.com/projects/eversource-geothermal
