Actually, it is practical, it does work and it has been implemented. What Dr. K neglected to mention in his article is that this is not a method for generating energy. It is a method for storing excess energy that has been fed into an electrica until it is needed. The excess energy is used to move the water uphill into a reservoir. When there is a large demand for energy that exceeds the systems generating capacity, the water is released to go back downhill powering a hydoroelectic generator. When the system is generating excess energy again, the process begins all over again. This is particularly useful for electrical grids that get a lot of excess energy generating during the day time by solar or that generates a lot of power by windmills on particularly windy days. You would know this if you were actually knowledgeable about the energy industry like you so often claim to be.