As the push for building decarbonization accelerates, one solution is quietly gaining momentum: geothermal networks. In this two-part blog series, we sat down with Kai Palmer-Dunning, Senior Associate of Building Decarbonization at Clean Energy Works, to explore how this innovative approach works, why it’s gaining traction, and how it can support an equitable transition away from fossil fuels. In Part One, Kai breaks down the basics: what geothermal networks are, why they’re more cost-effective than individual systems, and where they’re already working in the real world.
Kai Palmer-Dunning is Senior Associate of Building Decarbonization at Clean Energy Works. He has experience working on topics related to building energy codes, building decarbonization policy, and environmental justice. Prior to Clean Energy Works, he was the Director of Equitable Building Transition at the Home Energy Efficiency Team (HEET), where he helped guide programs related to improving access to weatherization and building retrofits in environmental justice communities. He also helped expand awareness of networked geothermal as a gas transition pathway. In addition to his work at HEET, Kai served as a review board member for Boston’s building performance standard, BERDO. He is completing his B.S. in Environmental Science and Data Analytics at Southern New Hampshire University and plans to pursue a Masters of Architecture in Sustainable Design.
What are geothermal networks and how do they work?
Geothermal networks describe interconnected networks of buildings that use underground pipes to share thermal energy for heating and cooling. Geothermal networks are a non-emitting, clean way of heating and cooling because they use geothermal energy or waste heat. The buildings in a geothermal network all have ground source heat pumps, which make the system more efficient and allow it to be networked.
Because underground temperatures stay around 50–60℉ year-round, geothermal networks can move heat between buildings through a closed-loop system that is far more efficient than air-source heat pumps. The ground source heat pump in the building draws on this stable temperature for heating and dumps heat for cooling through heat exchange. Water or a water-glycol solution flows through the pipes, carrying thermal energy where it’s needed, either for heating or cooling.
Some systems rely solely on exchanging heat between buildings while others use boreholes connected to the loop as base energy load and thermal batteries to store energy when it isn’t needed. You may also hear other terms used to describe similar technologies.
What makes geothermal networks a more effective solution for decarbonizing buildings compared to individual ground source heat pumps (GSHP)?
Individual ground source heat pumps are extremely efficient systems, consuming 25-50% less energy than already efficient technology like air source heat pumps. However, the high upfront cost of installing individual ground source heat pumps can be out of reach for many households. Geothermal networks offer a more affordable solution by sharing the cost of underground infrastructure across multiple buildings. While households may still need to cover the cost of installing ductwork and a heat pump, the shared infrastructure, if owned by a utility, can be included in the utility’s rate base.
These networks also become more efficient as more buildings are connected, especially if those buildings have different heating and cooling needs. For example, a data center that generates excess heat can share that heat with nearby homes in the network, reducing waste and energy use for everyone.
Geothermal networks are considered a gas transition pathway. Why is that?
Many states are working to move away from methane gas as a fuel source for space and water heating in buildings due to the greenhouse gas emissions from this fuel source. States like Massachusetts, Illinois, New York, Colorado, and more are undertaking proceedings to figure out next steps to phase out gas systems. Geothermal networks offer a decarbonized means for heating and cooling, while using less electricity than air-source heat pumps. This can help lower energy costs and minimize challenges associated with load growth from electrification.
Can you share examples of successful geothermal network pilot programs or large-scale implementations? What made them work?
Several exciting geothermal network projects have been launched in the last few years. In Framingham, Massachusetts, Eversource is leading a 24-month pilot — the first utility-owned geothermal network project in the U.S. — serving 125 customers (24 residential and 5 commercial buildings) with three bore fields located on municipally-owned property. The project has gained widespread attention and support as the first utility-owned geothermal network project in the country, and its early success is thanks to strong support from the state’s utility commission, a focus on low-income households, and collaboration with local advocates and community groups.
Colorado Mesa University also offers a great example of a full-scale project. Since 2008, its geothermal loop system has provided heating and cooling to 16 campus buildings, meeting 90% of energy needs and saving over $1.5 million annually compared to conventional heating and cooling systems. The system continues to grow, with $6 million in new state funding and plans to expand service to other municipal buildings. It’s a powerful demonstration of how geothermal networks can scale effectively.
In Part 2, Kai dives deeper into the barriers to scaling, what equitable deployment looks like, the role of inclusive utility investments, and how policy, utilities, and community voices can work together to bring this solution to more places. Stay tuned!
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