Background: Raccoon Mountain pumped store is one of the largest in the United States holding the equivalent to 12% of the total energy used in Tennessee in one day. Both nuclear and solar PV need energy storage to maximize the return on investment. Pumped storage of water is the most cost effective massive energy storage method known today. Construction at Raccoon Mountain began in 1970 and was completed in 1978. The reservoir constructed at the top of the mountain has 528 acres of water surface. The dam at Raccoon Mountain’s upper reservoir is 230 feet high and 8,500 feet long. It’s the largest rockfill dam ever built by TVA. Raccoon Mountain Pumped-Storage Station is a hydroelectric facility. It has four generating units with a net dependable capacity of 1,652 megawatts. Net dependable capacity is the amount of power a plant can produce on an average day, minus the electricity used by the plant itself. Several units at the 600 MW Raccoon Mountain pump storage facility were taken offline in 2010 due to rotor cracks.
Update on the status of the repair work at that plant by Bill Johnson. In an interview with Power Engineering Mr. Johnson, President of TVA, said that all four of those units were taken out of service after the discovery of cracks in the rotors. “There’s a similar plant in Europe where the cracks were first discovered, and when we inspected here we found the same thing. We are having new rotors manufactured in Europe. I would expect the first unit to be back online around July of this year, and the other three probably in the next ten to twelve months. We’re actively working on that. While the plant was down, we’ve done a lot of other things: replaced transformers, did some other things, but I would hope that we’ll see the first unit coming back in the July timeframe.”