Minnesota housing project to draw energy from water stored deep underground, 45 years on from city’s initial research

Nearly half a century ago, the US Department of Energy launched a clean energy experiment beneath the University of Minnesota with a simple goal: storing hot water for months at a time in an aquifer more than 100 metres below ground.

The idea of the seasonal thermal energy storage was to tuck away excess heat produced in summer, then use it in the winter to warm buildings.