Eversource may turn on its pilot program to set up a community-wide geothermal heat pump system in Framingham, Mass., this year. A lot of folks will be watching.

The project is pretty straightforward – it’s district heating that sends water instead of fossil fuels to lots of buildings and powers heat pumps instead of thermal units. The uncertainties that the pilot will be testing aren’t technical so much as financial and whether customers will like heat pumps as much as their gas-fired furnace and electric air conditioning.

I’m sure you know how ground-sourced heat pumps work: constant underground temperature carried to the surface by some liquid in pipes is used to reduce the energy that a heat pump needs to cool or heat a building. In this project a whole bunch of boreholes were drilled around a couple of neighborhoods, primarily under parking lots, that carry water via a couple of huge loops to electric heat pumps in the residential and commercial buildings that signed up. Eversource’s site discussing the project is here.

Eversource had a webinar recently updating the status. Most of the heat pumps are furnaces or boilers that send ducted air throughout the building, although minisplits are also possible. The existing heating system, usually gas, is disconnected, with an electric-resistance backup installed in case things go wrong.

Construction is continuing through the summer and by fall customers will be converted, so everybody online for the heating season this year. About 80% of residential homes along the route opted to participate, according to the webinar. Customers will be charged a flat monthly rate based on existing gas rates, with discounts available for low-income folks.

The project will run for two heating/cooling seasons to see how well it works, how customers like it and whether Eversource makes enough money to justify the expense. There will also be an independent monitoring agency, we were told, that among other things will help determine the extent of environmental benefits over using natural gas or other fossil-fuel heating.

i wrote about the project last year (article is here)

Framingham was chosen because it’s a relatively dense community, with lots of potential customers close together and because Eversource provides both its electricity and natural gas, which simplifies billing and customer acquisition. Creating a system like this would be tougher in places that have separate utilities for natural gas and electricity, like most of New Hampshire, because they’d fight over who got to profit or would trip over regulatory limits.