Energy Advisor: Oceans may hold answer to electricity production
Published: December 12, 2004
Dear Energy Adviser: I understand that a Washington state company is conducting research on a machine that would generate electricity from the movement of ocean waves. How practical is this and when are we going to see it hit the market?
Answer: As world oil production peaks and begins to decline, and as the scientific community provides more evidence of global warming, efforts to harness other energy sources are increasing. In addition to other renewable energy technologies solar, wind and tidal power one area that looks very promising is harnessing the energy of motion from ocean waves.
According to the World Energy Council, a multinational energy organization, as much as 10 percent of the world's electrical demand could be someday produced from wave action.
The potential along the West Coast of the United States is approximately 440 terawatt-hours per year. That equals the total energy output of the nation's hydroelectric system and all the other currently developed forms of renewable energy, according to the U.S. Energy Information Agency.
The trick is harvesting that energy. Worldwide, there are few functioning wave-energy generators.
Seattle-based Aqua Energy Group, Ltd., has proposed a pilot study of a one-megawatt (1 million watts) wave-energy power plant in the Olympic Coast National Marine Sanctuary, just south of Cape Flattery. This project would be the first wave-energy project in North American waters, and would test the environmental impact and feasibility of near-shore wave-energy power plants.
Using floating wave energy converter devices called AquaBuoys which look similar to a fishing bobber with a long tail the project is expected to deliver enough electricity to power about 100 homes.
As the AquaBuoy bobs up and down, water is pushed up through the "tail" of the buoy, turning a turbine-driven generator. Power from each AquaBuoy is combined and sent to shore via a marine cable on the ocean bottom. The project is expected to begin within the next year or two.
Another wave-energy-based technology, developed by Ocean Power Delivery of Scotland, is the Pelamis Wave Energy Converter. The Pelamis device, currently undergoing ocean testing at the European Marine Energy Center in Orkney, Scotland, is a series of hollow tubes that float on the water's surface. As waves move past the Pelamis, it undulates up and down and back and forth in an action similar to a snake swimming. Generators at the joints of this device translate this movement into electricity.
While lagging behind wind and solar in commercial development, ocean wave power is a more promising resource than either.
One major advantage of wave energy is its consistency. Because waves are always being generated, power produced from them is much steadier and more predictable. Unlike wind and solar, wave power is produced around the clock, making it a much more attractive investment for utilities and other investors.
Another advantage of wave-energy generators is that they require less surface area than either wind or solar generators. A wave-generator farm anchored several miles offshore would have significantly less visual impact that a wind farm near a mountain pass.
While not the total answer to the world's energy demand, power produced from harnessing ocean waves could play an important role in meeting future energy needs.
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