Old Mines Could House New Energy

Abandoned open pit mines on Minnesota’s Iron Range could be repurposed to work like a battery to store wind energy during low periods of demand, according to a new study by the University of Minnesota Duluth’s Natural Resources Research Institute.

Using a process developed in Europe during the late 1800s, the process involves using excess late-night wind energy to pump water uphill from the pits to a higher-elevation holding pond. When electric demand rises during the day, the upland water is released, flowing back through hydro turbines to generate electricity, the Duluth institute explained in its announcement. Only about 20 percent of efficiency is lost through the process.

“The altered landscape of the Iron Range makes it ideal for this purpose,” Don Fosnacht, institute center director and the study’s lead investigator, said in a news release. “There are over 100 mining pits, and those near ridges or cliffs would provide the necessary water reservoir prospects to allow the concept to be practically implemented.”

Minnesota Power has a wind farm in Mountain Iron called Taconite Ridge, but the system could also be used by other power generators.

“Minnesota Power will continue to assess energy storage development and the role pumped hydro might play in its long-range plans to best serve our customers,” said Al Rudeck, vice-president of strategy and planning for Minnesota Power. “This study provides a good basis for that continued assessment.”

“We feel that this technology could be a very good fit with our existing wind power and increasing renewable energy requirements,” said Rick Lancaster, vice president, generation, at Great River Energy.

The study was funded by the University’s Initiative for Renewable Energy and the Environment (part of the Institute on the Environment) with additional contributions from Minnesota Power and Great River Energy. It weighs a variety of considerations necessary to implement the concept using existing reservoirs on the Iron Range.

This story first appeared on BusinessNorth.com.