The Twin Cities are bringing back an idea first tested by DOE under the University of Minnesota in the 1980s. (Inside Climate News)
That idea? Storing heat in an underground aquifer and using it to run a neighborhood’s entire heating and cooling system. St. Paul’s 112-acre Heights development will be the first US project in decades to deploy the tech at scale.
How it works: Six deep wells will tap a stable 50°F aquifer that serves as both the heat source and the seasonal battery. In summer, excess heat can be pushed underground. In winter, heat pumps draw it back up at far higher efficiency than air-source systems—no matter how hot or cold Minnesota gets above ground.
Worth noting: The US largely abandoned aquifer thermal storage after 1980s field trials, even as thousands of systems spread across Europe. Federal geothermal tax credits have reopened the door, though, covering roughly half the cost of the Heights system.