I love the simplicity of water / gravity energy storage. https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity https://en.wikipedia.org/wiki/Pumped-stor

I love the simplicity of water / gravity energy storage. https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricit... It obviously requires the right kind of terrain etc, but it is very very cool.