One of the problems facing the distributed renewable power is that sometimes zapping the electricity down wires isn't your best choice, either for reasons of efficiency or of convenience. The Paul Scherrer Institute (PSI) and the Swiss Federal Institute of Technology Zurich have come up with a novel solution, at least for solar power: store it in a metal ore.
Solar heat is used to crack zinc from zinc oxide; the metal can then be readily moved around. The zinc can then be used in zinc-air batteries or to help crack hydrogen from water vapor. In both cases, the reaction with oxygen creates zinc oxide, which can then be used by the solar heater.
The first trials of the solar power-plant have used thirty-percent of available solar energy and produced forty-five kilos of zinc an hour, exceeding projected goals. During further tests this summer a higher efficiency is expected. Industrial size plants, for which this is a prototype, can reach efficiency levels of fifty- to sixty-percent. The success of this solar chemistry pilot project opens the way for an efficient thermo-chemical process whereby the sun's energy can be stored and transported in the form of a chemical fuel. In this process the zinc is combined with coal, coke or carbon biomass which acts as a reactive agent, yet in this reactor only a fifth of the usual amount of agent is used. The sun's rays are concentrated on this mixture by a system of mirrors and the zinc forms as a gas which is then condensed to a powder.
So the question for you engineering types out there: at what point does this become preferable to storing the power in batteries?
