An unusual sea creature is emerging from Loch Ness in Scotland: a monster-sized floating doughnut.
Wave energy startup AWS Ocean Energy recently tested this novel wave power device on the surface of the famous lake. Now, thanks to a recent investment from Alstom, a large French power equipment manufacturer, a 60-meter-diameter version could soon produce megawatts of power as it bobs in the open ocean.
The device is divided into cells, each consisting of inflatable rubber diaphragm and a bidirectional air turbine. Each cell faces toward oncoming waves. The diaphragm of each cell contracts under pressure from passing waves, forcing air through the turbines to generate electricity. The air is then fed either into a central collection chamber, or into the diaphragm of another cell elsewhere on the ring. Each time air passes through a turbine, whether exiting or entering a cell, electricity is generated.
“There is an exchange of air between cells which are out-of-phase,” says AWS chief executive Simon Grey. “This exchange is taking place via at least two turbines, exiting from one cell and entering another, and the ring main, at any given time.”
On June 21, Alstom made a “multimillion” dollar investment that will allow the Inverness, Scotland-based company to scale up AWS-III, it’s current generation of this wave energy device.
“AWS-III will generate two kilowatts for every ton of steel,” says Grey. “No other device comes within a factor of four of that.”
Philippe Gilson, ocean energy director for Alstom, says the size and modular nature of the device made it an attractive investment. “You get economy of scale and redundancy,” he says. “If one module fails, the others are still operating.”
AWS completed tests with a prototype of the wave-power device in Loch Ness in July 2010. The recent investment will allow the company to test a full-size, single-cell device in ocean waters in 2012. Grey says the hope is to then deploy a 60-meter-diameter floating ring with 12 wave-cell absorbers by the end of 2014. The full-scale device should generate 2.5 megawatts of power, more than twice as much as other wave energy devices deployed to date.
Vicky Coy, a senior consultant with the London-based engineering firm Arup, says the size of the planned device could be a liability. “There are only one or two places in the U.K. that can build something that big,” she says. “You would also have to have a large vessel to tow it into position, and finding ports that could accommodate it for servicing would be challenging.”