Nearing 500 buildings in Boise’s state capital find warmth by tapping into a clean and sustainable heat source, coming from beneath the ground. This unique method utilizes geothermal energy to provide nearly 500 businesses, government buildings, and homes, as well as hospitals and universities, such as City Hall and a Y.M.C.A, with heat that’s drawn directly from the ground’s hot water reservoirs, otherwise known as aquifers. The Idaho Statehouse stands as the only one in the United States to make use of geothermal heating, a system that also warms sidewalks in winter and boosts the temperatures of hot tubs. A series of localities adapting to environmental challenges through unique fixes unites under the title “50 States, 50 Fixes,” presenting Boise as one of the innovative participants this year.
Boise, abundant in natural hot springs due to its location in Idaho, has creatively utilized this hot water to establish the nation’s largest municipal geothermal system. The geothermal heating method is pollution-free, renewable, and dependable, and its viable in this city due to the presence of fault lines, which heat groundwater to around 77-degree Celcius, occurring naturally. Through a direct network of pipes reaching down into the buildings from the nearby hills’ wells, the hot water circulates, transferring its heat to adjacent pipe-water systems which warm each building.
Tina Riley, the geothermal development coordinator of Boise, pointed out the process of harnessing this resource by drawing water upwards, borrowing its heat for the buildings, and then returning it back into the aquifer. Over the past 40 years, the number of buildings powered by the city’s geothermal energy has risen six-fold. This shift towards cleaner energy sources has seen results, with 2024 calculations revealing a reduction of 6,500 metric tons of carbon dioxide emissions annually — equivalent to removing approximately 1,500 vehicles yearly.
Using geothermal resources for heating purposes was initiated in Boise in the 1890s, following the drilling of wells into aquifers providing hot water. The water heated various facilities, from public pools to homes in a region later known as the Boise Warm Springs Water District. The oil crisis in the 1970s prompted further development with the search for an affordable alternative to energy, thereby reviving interest in geothermal energy.
Today, Boise boasts four separate geothermal water systems: the city’s utility-run system, the Boise Warm Springs District system, and two systems serving the Capitol and U.S. Department of Veterans Affairs buildings. Each system operates with a focus on supplying geothermal heat at rates comparable to natural gas, yet proving more economical when used alongside heat pumps.
Scott Lewis, a technician in the Boise Warm Springs Water District, emphasized the cost-effectiveness of geothermal heating, particularly for older, non-weatherized Victorian homes. This method significantly reduces stress on the power grid, with the monthly operational cost for providing heat to over a million square feet at $1,800.
The geothermal network’s expansion and popularity are driven by both its cost-effectiveness and the environmental awareness of the community. With visitors from around the globe showing interest in Boise’s unique system, the city’s geothermal infrastructure has become an attractive feature that draws international attention.
Source: https://www.nytimes.com/2025/03/25/climate/boise-idaho-geothermal.html
