Unique HPP away from water

Very unusual hydroelectric plant is located near the town Lestervill, Missouri. To the nearest source of water - about 80 kilometers. How, then, does it work and is it necessary at all?

This power plant consists of two spaced apart from each other and only the parts of the peak moments in the electrical load. A water tank opens, and water flows down to the turbine. Once the load in the network falls, the water using the residual power back into the tank. Thus, it appears that the HPP can be considered a self-contained battery. The cost of the project at the time of launch in 2010, the year amounted to about half a billion dollars. The tank holds about 5 billion cubic meters of water.