Networked geothermal
District heating and cooling system using shared geothermal loops
From Wikipedia, the free encyclopedia
Networked geothermal is a type of district heating and cooling system in which a shared water loop exchanges are heated with the ground, usually through shallow geothermal boreholes, connecting multiple building-level heat pumps.[1][2]
Unlike conventional district heating systems that distribute steam or high-temperature water from a central plant, geothermal energy networks (GEN) generally circulate water at relatively low or ambient temperatures. Individual buildings use water-source heat pumps to raise or lower temperatures for space heating, cooling, and sometimes domestic hot water.[3][4] In technical and policy literature, geothermal networks are commonly described as a form of thermal energy network or as part of fifth-generation district heating and cooling.[3][5]
Terminology
The terminology used for geothermal networks varies by jurisdiction and source. In engineering literature, similar systems are described as geothermal district energy systems, ambient-temperature loop districts, or are grouped within fifth-generation district heating and cooling systems.[3][5]
In U.S. media, policy, and utility contexts, such systems have also been described as networked geothermal.[6][7]
Design and operation
A geothermal network typically consists of a shared buried pipe loop carrying water or water-antifreeze solution, a set of geothermal boreholes or other ground heat exchangers, pumps and controls, and building-level energy transfer equipment, usually water-source heat pumps.[3][4]
In many designs, the network loop operates near ground temperature rather than at the higher temperatures used in earlier district heating systems. Buildings needing heat extract it from the loop through heat pumps, while buildings needing cooling reject heat back into the loop. Because heating and cooling loads may occur at different times across a district, some systems are designed to exchange heat between buildings and to use the ground for thermal energy storage or seasonal thermal energy storage.[3][5]
Development
District-scale geothermal heating and cooling systems predate the recent use of the term geothermal network, but the concept received increased attention in the 2020s as part of building decarbonization policy in the United States.[4][8]
In Massachusetts, Eversource Energy developed a pilot geothermal network in Framingham, Massachusetts. A 2025 PBS NewsHour report described it as a one-mile system connecting about three dozen homes and municipal buildings to a shared geothermal bore field.[7] Independent reporting by Grist also described the Framingham project as a networked geothermal system serving residential and commercial buildings through shared underground infrastructure.[6] The Framingham project was presented in reporting as an early test of whether gas utilities could shift part of their business from natural gas distribution to shared thermal infrastructure.[9]
Policy and regulation
In the United States, geothermal networks have increasingly been discussed in relation to utility regulation, labor transition, and building electrification. In 2022, New York enacted the Utility Thermal Energy Network and Jobs Act, establishing a legal and regulatory framework for utility thermal energy networks.[10] The legislation described thermal energy networks as ambient-temperature water loops connecting multiple buildings and energy sources, with building owners connecting through water-source heat pumps.[10]
In July 2024, the New York State Public Service Commission adopted initial rules for utility thermal energy networks.[11] Maryland enacted legislation in 2024 authorizing thermal energy network systems.[12] Massachusetts issued state guidance for networked geothermal projects in 2024.[13]
Applications
Geothermal networks have been proposed or deployed in university campuses, mixed-use developments, housing complexes, and neighborhood-scale utility pilots.[4][8] According to PBS NewsHour, the Framingham pilot served detached houses as well as a school administration building, a fire station, and a public housing development.[7]
These systems are used mainly for space heating, air conditioning, domestic hot water, and load balancing between buildings with different thermal demands.[3]
Limitations and considerations
The performance and economics of geothermal networks depend on local geology, drilling conditions, load diversity, building retrofit requirements, and financing structure.[3][5] Other issues discussed in the literature include capital cost, street excavation and siting constraints, coordination among property owners and utilities, and the regulatory treatment of thermal service.[14][11]