The Wave of the Future?

How nickel stainless steels could help extract electric power from waves
By Dr. Dr. G. Crawford

Nickel Magazine, December 2007 -- The amount of electricity generated from renewable energy sources is increasing worldwide, and nickel-containing materials are playing an enabling role. Mention renewable energy and most people think of solar cells and windmills. It turns out, though, that a thousand times more energy is contained in ocean waves.

Waves are therefore a potentially more appealing source of renewable power. If only the energy could be extracted profitably. . . .

Perhaps it can be.

A prototype of a wave energy machine, AquaBuoy, has been tested in the Pacific Ocean, off Newport, Oregon, in the northwestern United States. Developed by a Canadian company, Finavera Renewables Inc. of Vancouver, AquaBuoy is a cylindrical device that floats vertically in the ocean and bobs up and down under the action of the waves. Only the top portion of the AquaBuoy is visible above the surface. The current prototype is half-scale; full-size units will be 13 metres in diameter, 48 metres long, and weigh about 65 tonnes.

The longer, submerged portion of the largely empty cylinder has a piston that moves up and down with the waves, pushing water alternately up and down through “accelerator tubes” to two-stroke hose pumps that pressurize the water and direct it to a Pelton turbine, one of the most efficient types of water turbines in high-force, low-flow situations. The turbine in turn powers an electric generator in the upper portion of the device. Power then flows through an underwater cable to on-shore users.

Each AquaBuoy has the potential to generate up to 250 kW in 4-to-5-metre waves.

Groups of them deployed off-shore in various arrays could produce tens of megawatts of renewable electricity.

In addition to the piston, accelerator tubes, pumps and Pelton turbine, various check valves, manifolds, and other piping, are all exposed to the corrosive effects of seawater. There is an obvious need for nickel-containing stainless steels and other nickel alloys for many, perhaps all, of these components.

Wave energy is limitless, and so therefore is the potential to harness it for power generation. It all hinges on reliable technology and economic costs. There will doubtless be a series of AquaBuoy prototypes, each improving on earlier versions, and assuming the technology proves reliable and the economics are acceptable, wave power could become a huge market for nickel steels and other nickel alloys.

Dr. G. Crawford is a Mississauga, Ontario-based consultant to the Nickel Institute.

Photos: Finavera Renewables Inc.

Finavera Renewables Inc. 595 Burrard Street, suite 3113 |Three Bentall Centre, PO Box 49071 Vancouver British Columbia Canada V7X 1G4 Tel: 1- 604-288-9051 Fax: 1- 604-684-2722 E-mail: info@finavera.com Web site: www.finavera.com

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