A small island nation off the coast of Spain is run on 100% renewable power. El Hierro isn't the only country capable of this level of sustainability, but is unique in that it uses a combination of wind energy and a volcanic crater to do this. While other states might be close, El Hierro will be the first to fully supply its population of 10,000 with wind and hydroelectric energy.
In addition to a wind farm being installed in the north of the island, a volcano's crater will act as an energy storage device. This volcanic reservoir will provide renewable energy on calmer, less windy days as electricity is generated from partial draining and the resulting kinetic energy from water running down the volcano. Together, these two processes will work similarly to a Rube Goldberg machine.
The Island Nation of El Hierro Runs Sustainably on 100% Renewable Power
Alyson Wyers — May 9, 2014 — Eco
References: goronadelviento.es & fastcoexist