ST. PAUL, Minn.—Nearly half a century ago, the U.S. 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 several hundred feet below ground.  The idea of the so-called seasonal thermal energy storage was to tuck away … Continue reading Decades After the U.S. Government Conducted Research Beneath This City, a Promising Clean Energy Technology Returns to Its Roots