Catching waves: A U.K.-based company has come up with a simple design for a device that harnesses wave power: a water-filled rubber tube floating just under the ocean’s surface. Waves create bulges inside the tube that travel along it and drive a turbine attached at the other end.
Engineering and Physical Sciences Research Council, UK
New technology could provide a way to harness wave energy.
The ocean's waves have enough energy to provide two trillion watts of electricity, according to the Department of Energy's office of Energy Efficiency and Renewable Energy. Extracting that enormous resource of power, however, has proved to be a herculean challenge.
A new device being developed by U.K.-based Checkmate SeaEnergy could help tap a portion of this wave power. The device, aptly named the Anaconda, is a long, water-filled rubber tube closed at both ends. It currently exists as a small laboratory-scale model, but it could eventually be 200 meters long and seven meters in diameter. At such a size, it will be capable of generating one megawatt of power at about 12 cents a kilowatt-hour, which is competitive with electricity costs from other wave-power technologies.
The one-megawatt Anaconda, which will use about 110 tons of rubber, should be lighter and cheaper than other wave-exploiting designs, says John Chaplin, a civil-engineering professor at the University of Southampton, in the United Kingdom, who is testing the lab-scale device. It is also simpler, with fewer moving parts and hinges, which means less maintenance. Since it is a pliant rubber tube, it should be able to survive severe weather conditions. "We don't really know how Anaconda works in big waves yet, but intuitively, it seems likely that it's going to be able to survive big waves," Chaplin says.
The Anaconda will face plenty of competition from other wave-power devices that have already reached commercial-scale deployment. Scotland-based Pelamis Wave Power's snakelike device was the first to provide power to the grid when it was installed off the coast of Orkney, Scotland, in 2004. In October 2007, Pelamis deployed three of its 750-kilowatt devices--770-ton, 120-meter-long chains of metal cylinders--off the coast of Portugal. Other companies, such as Finavera Renewables of Vancouver, AWS Ocean Energy of Scotland, and Ocean Power Technologies of Pennington, NJ, are testing bobbing buoy-type devices. In addition, others are developing technology to exploit tidal energy.
The Anaconda floats horizontally just below the ocean's surface, tethered to the ocean floor at one end, facing oncoming swells, with a turbine attached, at the other. A wave hitting the tube creates a bulge in the water inside. The bulge travels down the tube with a speed that depends on the diameter of the tube, wall thickness, and elasticity of the material, Chaplin says. The tube is designed so that the speed of the bulge is the same as the speed of the wave. The wave travels outside the tube alongside the bulge, making the bulge bigger and bigger, so that it drives the turbine with maximum power.
But the future of the wave energy industry could depend on the incentives introduced by the U.K. government.
The same principle can be used to harvest energy from winds that are on higher altitudes.
A giant balloon floats on 10-20 km (or higher) anchored from the ground with a cable. On every 100 meters a "rubber snake" that floats too (filled with helium or other gas) is moving and produces "energy". Instead of a big and heavy "magnetic engine" can be used a "pressure generator" (or another principle) ... so every snake that is placed along the cable produces a small "pressure" that travels to the ground and spins a giant "generator"...
While a cost at $.12 a kWh may be competitive with other wave energy sources its more then 2 time the cost of coal at $.05 a kWh whole sale.
While research into clean renewable energy sources is desirable. It would be foolish to replace existing energy sources with a renewable energy source at more then twice the cost.
To make huge investments into commercial scale power plants using energy sources that have the uncompetitive cost would be incrementally destructive for your business or governmental entity.
For all those who are impatient with the speed at which new technology comes to market let this be the lesson that it needs to make business sense first, Else your business or government will fail.
I'd like to add: if $.12 kwh wholesale is competitive for your locality's energy market then by all means add this to your energy infrastructure.
Manufacturing in the United States is in trouble. That's bad news not just for the country's economy but for the future of innovation.
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mkogrady
423 Comments
Submersed Units
How deep are these anchored? If rather shallow, then large swells and hurricane energy could snap these like one does a whip. I suspect that at deeper levels, these may pick up the C or P-Waves and ocillate at a slower - yet predictable pattern and be protected from surface wave damage.
Also - are these to be anchored in oceans or are the great lakes a seasonable alternative? These bodies of water are subject to waves too, just not as large. Superior, Michigan and Huron all pick up good sized swells - some in the 15 to 20 foot range, and a scaled anaconda unit could provide power to the mid wesk and even parts of Canada and New York.
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