Harnessing wind and wave power
A study by Australian, American and Canadian scientists suggests that high-altitude wind power could provide a major source of renewable energy in years to come.
Their paper--in the March 1 edition of the journal IEEE Transactions on Energy Conversion--provides detailed technical specifications for a prototype flying wind turbine that could generate far more energy than a ground-based turbine.
The authors wrote that jet stream winds have 10 to 100 times the energy of winds close to the ground.
“This is the highest power density for a large renewable energy resource anywhere on earth,'' they wrote.
The flying wind turbine they described amounts to a tethered gyrocopter flying as a kite, whose spinning blades would generate both lift and electricity. The lift keeps the gyrocopter in the air and the electricity is transmitted down the tether to be used on the ground.
Carnegie Institution senior scientist Ken Caldeira, one of the study's co-authors, wrote in an e-mail that the paper “makes it clear that there is a case to be made that these kind of aircraft could be a major piece of the solution to the climate problem--just tapping into 1 percent of the energy in high altitude winds would be enough to power all of civilization.''
Rise & fall
Off the western coast of Scotland, on the Isle of Islay, science teacher Ray Husthwaite turns on the light in his classroom.
The electricity comes from a power cable that runs to the mainland. But it also comes from the ocean. A few miles from the school, wave action compresses and decompresses air in a chamber. The moving air powers a turbine, which generates electricity.
In a world addicted to fossil fuel, turning waves into watts might seem far-fetched. But as the U.S. and other countries look for alternatives to oil, natural gas and coal and try to curb global warming, ocean power gradually is joining the ranks of wind and solar power as a source of renewable energy.
Pacific Gas & Electric Co. caught the wave last month when it became the first California utility to file for permits to study the promise of sea power, a non-polluting but expensive and untested way to make energy.
PG&E's proposed projects could provide electricity for tens of thousands of homes, said Keely Wachs, spokesman for the San Francisco-based utility. '
In less than three years, U.S. energy regulators have received nearly five dozen applications for water-related energy projects. Although wave power does not create pollution, questions have been raised about potential harm to marine life, the coastline, fishing and boating operations and ocean views.
L A Times
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