The Energy Storage increases your energy storage capacity by 6000.
Great for powering weapons that consume large amounts of energy.
It's also useful for storing excess energy for later use, and to reduce energy stalls when wind speed is low or if you lose your generators.
Energy Storages explode for high damage in a large area when killed, even higher when self-destructed. You can exploit this by deliberately building it as a bomb right where enemies may invade from.