Boise plans to tap its geothermal network to heat 300 affordable homes

Boise operates the nation’s largest geothermal heating system, piping 177-degree underground water to about 100 buildings, including the Idaho State Capitol. The city plans to extend this network to a new affordable housing development with over 300 units, with construction expected to begin in spring 2027 and completion slated for 2028. The total project cost is approximately $140 million, funded in part by a $2.5 million grant from Micron Technology’s philanthropic arm. The expansion aligns with Boise’s goal of achieving carbon neutrality by 2050.

The geothermal network currently reduces thousands of tons of carbon emissions annually, equivalent to removing over 2,000 gas-powered cars from the road. A $1 million grant from the Bloomberg Philanthropies Mayors Challenge will also help upgrade the system and explore using the hot water for cooling applications. The city’s Housing Land Trust Program is partnering with J. Fisher Cos. to develop the affordable multifamily housing project in the Lusk District.

Because geothermal energy is free once the infrastructure is in place, residents could save up to 80% on utility bills compared to conventional heating. The project aims to provide clean, affordable heating to households that might otherwise face high energy costs. Mayor Lauren McLean emphasized the importance of partnerships in making housing more accessible while advancing sustainability goals.

Geothermal heating networks are expanding across the U.S., with 33 projects in various stages of planning, construction, or completion. Similar systems are being developed in Denver, Enfield, North Carolina, and Framingham, Massachusetts, where a utility-owned network serves 140 customers. Federal grants, such as the $8.6 million awarded to Framingham’s project, are supporting the growth of these climate-friendly energy solutions.