GENERATION

The World's First Wave-Energy Generator

Anyone who has ever paddled into the ocean and been knocked sideways by the power of a wave might have wondered: "If only that power could be harnessed and turned into energy".

For more than five decades, engineers have had the same thought, working on plans for generating electricity from wave power. In the 1950s, for example, a company based in the United Kingdom devised a plan to harness waves off the coast of Mauritius.

But, until very recently, such schemes have remained just a good idea. Now, in a remarkable development, the ocean's waves are being tapped commercially for the first time.

From the coast of a beautiful Scottish isle, Islay, waves are being harnessed to feed the world's first commercial wave-power station. Late last year, the station successfully began to feed electricity into the UK's national grid.

Known as Limpet (short for land-installed marine-powered energy transformer), the system has been developed by an Inverness-based renewable energy company, Wavegen, and Queen's University Belfast, Northern Ireland. The European Union has helped with funding.

The Limpet device is a half-megawatt commercial wave-energy converter, providing power to the national grid with enough electricity for about 400 homes. Limpet harnesses the Atlantic Ocean waves that pound the Islay coastline with the aid of two basic devices: a collector chamber to capture the wave energy, and a turbo-generator to transform its power into electricity.

The wave-energy collector is in the form of a partially submerged shell into which sea water is free to enter and leave. External wave action causes the water level in the collector to oscillate. As the water enters or leaves, the level of water in the collector chamber rises or falls in sympathy.

The turbo generator then comes into play. This makes use of Wells turbines. "These have the unique property," said Wavegen, "of turning in the same direction regardless of which way the air is flowing across the turbine blades".

Thus, the turbines continue turning on both the rise and fall of wave levels in the collector chamber. The turbine drives the generator which converts this power into electricity. The system has been developed after 20 years of collaborative academic research, and 10 years after Queen's University Belfast (QUB) installed a small research wave-energy station on Islay in 1990. The successful operation of this plant led to the Limpet project.

Established in 1992 by Allan Thomson and Professor Alan Wells, inventor of the Wells turbine, Wavegen has pioneered the research, development and manufacture of wave power systems. The power station has secured a 15-year agreement with the major public electricity suppliers in Scotland. But the development of Limpet has much wider implications.

Oceans cover about three quarters of earth's surface and represent a vast natural energy resource in the form of waves. The World Energy Council estimates the energy that could be harvested from these oceans is the equivalent of twice the planet's electricity production.

The Limpet system is designed to operate right on the shoreline. Alternatively, units may be incorporated in rubble mounds or breakwaters to provide self-financing coastal protection schemes, providing power or potable water to communities.

The new power station in Scotland opens the door for wave power to make a serious contribution to energy supplies and help to reduce emissions of climate-changing greenhouse gases. The European Union is funding research and demonstration activities to bring renewable energy source into the energy market.