POWER FROM THE SEA

The sea is a sea of energy. It has vast deposits of oil and gas beneath it, thermal gradients to power sea-solar power plants, tides to be harnessed by hydropower plants, and an inexhaustible supply of the fuel for the ultimate energy supply - deuterium for nuclear fusion.

And on top of all that (so to speak) it has waves. Their energy is now occasionally harnessed in minute amounts; for example, the US Coast Guard is about to power buoys by wave motion. which will pump air into an internal duct to spin a turbine. This generates electricity for lights, whistles and horns.

Chickenfeed, said researchers at the University of Edinburgh. who are used to bigger waves, and they looked into the possibilities of the real thing: 500 MW, enough electric power for 600,000 Americans. and for a lot more Scotsmen, who skimp more on electricity.

The energy would be harnessed by 10 semisubmersible steel and concrete structures, each 1 km (5/8 of a mile) in length, whose 20 to 40 cams or vanes would rotate on a horizontal axis. The investment cost, it is claimed, would be comparable to that of a nuclear plant of equal capacity. The structures might not withstand the vicious waves of the North Sea, but the project calls for installation (anchoring) off the Hebrides, to the west of Scotland in the North Atlantic.

The best way to transmit the energy to the mainland, according to the study, is to use the power for electrolysis of sea water and then pipe the hydrogen ashore - a conclusion in agreement with several US studies of solar sea power plants and offshore windmills.