Hawaii Taps Oceans For Renewable Energy

"Different technologies are being developed to tap the motion of the oceans. One approach is to convert wave action into electricity through a concrete tube in which an oscillating column of water first compresses and then decompresses air trapped in the column. The motion of the air in turn drives turbines, which generate electricity.Another approach is to rely on large buoys, which rise and fall with the action of the waves, propelling built-in pistons that drive generators on the ocean floor to generate electricity."