Part of the difficulty of renewable energy sources like wind and solar is what to do when the energy isn't present. After all, the wind isn't always blowing and night comes pretty consistently, but our energy needs don't diminish.
One of the solutions that has been proposed in large-scale solar installations is the use of compressed air. When energy is available during the daytime, air is pumped into caves in the ground, like old mines. Then during the night, this air is released in a thin stream to turn turbines and generate electricity. The technique has been used before, but needs some more proving.
A UK professor has a tweak on this idea for water-based wind, wave, or tidal energy factories. Seamus Garvey, a long-time proponent of compressed air technology, proposes storing compressed air in huge undersea bags when winds and tides are high, and then pumping this air out when it is needed.
Power company E.ON has invested 300,000 Euros to allow him to build two prototypes. Professor Garvey says that the prototypes will be complete in 18 months. We'll definitely be keeping an eye on his progress.