Inductor
Inductors are a type of storage which tries to keep current flowing through it consistently by storing electricity when current is high, and discharging when current is low. When current passes through it, it will store a little of it within a magnetic field at the cost of some voltage. If the current dies out, the inductor try to keep the flow going by releasing its its charge. It acts similar to capacitor, though you will lose all your saved power if you disconnect it and unlike a capacitor the released current faces the same way as the input current did.
These require copper wires and a Ferromagnetic Core. The amount of copper wire inserted will set its inductance and the core will determine how much energy is wasted from the process.
Tips on usage
Inductors will store a LOT of power if you give them a very fast current. If you want to use an inductor for storage purposes, be sure to step up the current as much as you can get away with. Remember to step it down before reintroducing the power into your network, or you may instantly incinerate your wires with the tremendous amperage.