Producing electricity, from the sea

Press, 5 August 1980, Page 17

Producing electricity, from the sea

A test system to explore the feasibility of producing electricity from the energy stored in ocean waves will be developed by Lockheed Missiles and Space, Co., under a twoyear, $593,000 contract awarded . by the United States Department of Energy’s Solar Energy Research Institute. Called Dam-Atoll, the system to be built will be a l/50th scale model (5 feet in diameter) of a fullsize system that Lockheed estimates would be capable of producing from one to two megawatts. Dam-Atoll receives its name from its dam-like convex shape and its theory of operation, which uses wave action similar to that observed around small coral islands (atolls). Looking at a Dam-Atoll unit from the side, it resembles an open umbrella

with a short, straight handle. The unit operates almost totally submerged, with only the upper 10 per cent above water. As waves approach, they wrap .around the Dam-Atoll unit and enter a central core from all points. The waves actually change direction at the trailing edge of the unit and enter the rear of Dam-Atoll moving in the opposite direction to that in which they were originally travelling. Vanes on the top of Dam-Atoll channel waves into the 60-foot deep central core, creating a vortex or whirlpool in the core to. turn turbine blades and produce electricity. A continuous input of water in the core is maintained by the time lag provided by the waves’ wrapping action. As the old waves enter at the

rear and complete a wave cycle, new waves approach and enter in front to continue the process. Tom Higgins, the Lockheed programme director, says that a typical mile of ocean waves contains enough energy to reproduce approximately 64 megawatts. Given this energy potential, a string of 500 to 1000 Dam-Atoll units placed in a highactivity wave area, such as the Pacific north-west, might generate as much power as the Hoover Dam. “The total power delivered daily to the shores of the world’s oceans is almost equal to the total energy content of the world’s daily oil production,” Higgins says. “Ocean energy renews itself;, oil does not” Lockheed intends to conduct tests of . the scale model at its Ocean Laboratory in San Diego, wherg

ocean waves can be simulated in a 320-foot long tank. Higgins says an operational unit might be made of steel or reinforced concrete. Domelike steel structures similar in size to full-scale Dam-Atoll units already have been produced and are being used in the Middle-East to store oil underwater. Models of these structure also were tested in the Lockheed wave tank. One of the phenomena associated with Dam-Atoll is that a calm stretch of water approximately equal to the diameter of the Dam-Atoll is produced on the leeward side of the unit. By stringing a group of Dam-Atoll units together, a deep water harbour could be formed to unload petroleum and natural gas away from populated areas, .