One of the major challenges faced by wind and solar energy is that they aren't controllable in the same way coal, oil or nuclear energy is -- it gets dark at night and the wind doesn't alway blow.
Recently a MIT researcher demonstrted a more efficient way of using electricity to split water into hydrogen and oxygen for use in a fuel cell. The goal of this method would be to time shift the generation of electricity from wind or solar to when it would be needed.
An article about this method can be found at:
What do you think?