Eversource plans novel networked geothermal for heating and cooling

New England utility Eversource has broken ground on a US ‘first-of-its-kind’ networked geothermal system in Framingham, Massachusetts.

The company intends to pilot the system to investigate if it is a viable way to provide heating and cooling to homes and businesses instead of or in combination with traditional energy sources like natural gas, and if it can be expanded or replicated in other communities.

The project, which was approved in 2020, involves the drilling of over 100 boreholes with 37 buildings in the pilot – 32 residential and five commercial – for a total of about 140 customers within an area about 0.5km square.

Eversource intends to evaluate the pilot programme through two full heating and cooling seasons to determine if the technology is a cost-effective option that could be used as part of the clean energy transition in Massachusetts.

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“We all know that our state and our region face significant climate challenges and our geothermal project in Framingham is a great example of how we’ll build that clean energy future in addition to our investments in technologies like solar, battery storage, electric vehicle charging station and more,” said Eversource President, CEO and chairman Joe Nolan.

“While we aim to be a leader and a catalyst, we need collaboration and partnership to achieve the clean energy future that everyone wants. We’re here today because so many stakeholders are willing to support this test of a promising new technology.”

Test boreholes drilled last September along the pilot route enabled determination of the amount of heat that can be taken out and put into the ground, with the results feeding into thermal capacity modelling and system sizing, and drilling is now set to begin at the three locations for the system’s wells.

At the same time the main, which will be filled with propylene glycol for heat transport, will be installed along with the ‘Ts’ and equipment such as geothermal heat pumps to each of the participating buildings.

Eversource says that while geothermal heat pump systems are in use throughout the US and the world, its pilot is the first of its kind that is networked with multiple geothermal heat pumps connected through a shared horizontal piping system with the intent of optimising the various building loads to reduce the overall size of the loop.

The utility says Framingham was selected as a location with about 100 neighbouring residential, commercial and industrial customers in a relatively dense urban environment.

Participants also had to be existing Eversource customers.

Eversource provides electricity, gas and water services to about 4.4 million customers in Massachusetts, Connecticut and New Hampshire.