Surfing Energy's New Wave

The water comes in, the water goes out, propelled by the perpetual engine of the sun and moon. With 70% of the earth's surface covered by the restless tides and currents of the oceans, the idea of harnessing that movement to serve the planet's energy needs is too tempting to ignore.

Since the Middle Ages people have built tidal mills, trapping an incoming tide in a storage pond to turn a wheel as the water ebbs. But the dream has always been to tap the power of the ocean itself — to harness the force of...