Boise geothermal expansion targets 300 affordable homes

By Daniel Okafor

Semiconductor company Micron Technology gave Boise $2.5 million last week to help fill a funding gap for a geothermal heat-network extension serving more than 300 affordable housing units, part of a roughly $140 million project in the Lusk District.

How much geothermal capacity does Boise already have?

Boise’s city-operated geothermal heating system moves naturally warmed, 177°F water from underground to about 100 buildings, including the Idaho State Capitol. The city calls it the country’s largest geothermal heating system.

Boise says the operating network cuts thousands of tons of carbon emissions every year, equivalent to taking more than 2,000 gas-powered cars off the road. It also supports the city’s goal of becoming carbon-neutral by 2050.

That operating base matters: the proposed expansion would add housing capacity rather than create Boise’s geothermal system from scratch.

Where does the funding come from?

The $2.5 million Micron donation helps fill the city-identified gap for extending the network to the planned affordable housing development. Separately, in February, the Bloomberg Philanthropies Mayors Challenge awarded Boise $1 million to upgrade its geothermal system for affordable housing and explore a new use for the network.

City communications senior manager Maria Ortega said some early-stage technologies could potentially harness hot water from the system to provide cooling. That work remains exploratory rather than an announced cooling project with a construction schedule or operating capacity.

“Boise has been Micron’s headquarters for 48 years, and investing in this community means investing in the people who call it home,” April Arnzen, executive vice president and chief people officer at Micron and president of its philanthropic arm, the Micron Foundation, said in a statement.

Announced support stands at $2.5 million from Micron and $1 million from Bloomberg Philanthropies, against a project price of about $140 million. That support materially advances the extension, although the development remains much larger than the two awards.

When will residents get the network?

The Housing Land Trust Program has partnered with J. Fisher Cos. on the affordable multifamily housing project in the Lusk District. The partners expect to break ground in spring 2027 and have the development ready for residents in 2028.

According to the city, renewable geothermal energy itself is free, and the network could save residents up to 80% on utility bills.

“Building more homes that Boiseans can afford takes partners who are willing to roll up their sleeves and invest in solutions,” Mayor Lauren McLean said. “Thanks to Micron’s investment, we are one step closer to bringing clean geothermal heat to hundreds of affordable homes in Boise.”

For residents, the practical test is whether the project opens on schedule in 2028 and delivers the city’s projected bill savings.

What does the national market show?

The nonprofit Building Decarbonization Coalition counts 33 scattered U.S. geothermal projects that are planned, under construction or completed. The coalition says borehole-based systems can form part of thermal networks that move heat among buildings and provide gas utilities with a climate-compatible business model.

Denver plans to harvest heat from the earth and sewage to supply downtown buildings. The tiny rural town of Enfield, North Carolina, secured seed funding earlier this year for a geothermal network intended to lower residents’ energy costs.

In Framingham, Massachusetts, about 140 customers are the first in the U.S. to receive heating and cooling from a geothermal network owned by gas and electric utility Eversource Energy. Last December, that project received an $8.6 million federal grant to double in size.

The 33-project count shows a U.S. market spanning announced, construction-stage and operating developments, although geothermal heat networks still serve a limited number of communities.

What milestone comes next?

The next construction milestone is the planned spring 2027 groundbreaking in the Lusk District, followed by resident readiness in 2028. Until then, the city’s $2.5 million Micron donation and $1 million Bloomberg award must translate into a financed construction program, while the cooling work remains an early-stage study.

The spring 2027 groundbreaking is the milestone that decides whether the 2028 housing schedule holds.