MINNEAPOLIS / ST. PAUL — Minnesota’s Iron Range is pocked with ponds – abandoned open pit mines – that could help energy providers more efficiently use intermittent renewable energy sources, such as wind, to meet state renewable energy mandates. A study released Friday by the University of Minnesota Duluth’s Natural Resources Research Institute shows that the water-laden pits have the potential to store wind energy using a process developed in Europe in the late 1800s.
The pumped-hydro storage process would use excess late-night wind energy to pump water uphill from the pits to a higher-elevation holding pond. Then, when electricity demand goes up during the day, the process reverses the flow and captures the energy in hydro turbines. For every 100 megawatts used to pump the water upward, the plant generates nearly 80 megawatts through the turbines. (more…)