You are right, this is basically a gravity energy storage. It's the same idea as moving a 14m3 blob of water 100m up and down. Unfortunately, gravity storages h

You are right, this is basically a gravity energy storage. It's the same idea as moving a 14m3 blob of water 100m up and down. Unfortunately, gravity storages have really bad energy densities. Let's see. E = mgh E is the energy, m the mass, g the gravitational acceleration, h the difference in height. m = 14e3kg g = 10m/s2 h = 100m E = 14e6J = 3.9kWh The only gravity storages that have been proved to be scalable so far are hydroelectric. And they have huge lakes behind them.