Nelson Energy is a small Minneapolis based development company which over the last 20 years has focused on the addition of hydropower to existing nonpowered dams. Nelson has licensed five conventional hydropower projects, totaling 138 MW in Minnesota, Iowa and Louisiana. Both the Red Rock project and Lower St. Anthony Falls are operational while the three Louisiana projects are being developed by Natel Energy in cooperation with Nelson. Nelson’s current development focus is closed loop pumped storage projects utilizing underground reservoirs excavated with TBM’s. These projects can be sited in topographically challenged parts of the country which cannot support conventional pumped storage developments. This concept, which studies have shown is cost competitive with batteries and conventional aboveground pumped storage, was a prize-winning entry into the DOE contest to identify innovative techniques to bring cost-effective pumped storage online.