The movement of water in the world's oceans stores huge amounts of energy.
Now a team of engineers in the Scottish Highlands is setting out to prove they can harness it.They are pinning their hopes on Osprey 1 - a shovel-shaped submersible about to be positioned on the seabed off the north coast of Scotland.
Allan Thomson, managing director of Applied Research and Technology (ART), which designed the device, says Osprey - a near-acronym for Ocean Swell Powered Renewable Energy - will soon be generating 2 megawatts of electricity. "That is enough to supply about 2,000 homes," he says.
The place they have chosen to put Osprey is within sight of Dounreay, where Britain's first experimental "fast-breeder" nuclear reactor was built 40 years ago.
Thomson says Osprey is the world's first commercial wave-power generator and says it will be much cheaper and more adaptable than installations harnessing energy from the ebb and flow of tides.
ART towed Osprey to the turbulent waters near Dounreay and sank it about 300 yards offshore Aug. 10. It is now being wired into Britain's national electricity grid.
The technology Osprey uses is disarmingly simple. It is held in place on the seabed by its own weight and operates by trapping the swell of the ocean inside a "collector" vessel.
As the swell rises and falls inside the collector, air is pushed out and sucked in through the top of the structure, turning a turbine in the process. The turbine connects to a generator, feeding power into the grid.
So far, the project, which has been in the making for five years, has cost 3.5 million pounds ($5.6 million). Funding has come partly from a European Union development fund and partly from commercial companies. The British government has contributed nothing.
Thomson is confident that Osprey will work as planned, but some scientists express doubts. Donald Macdonald, a researcher at London's Imperial College of Science and Technology, says a likely enemy will be the sheer force of winds in the north of Scotland. "Once or twice a year, it blows a real gale up there, and virtually nothing remains unless it's a granite lighthouse," he says.
But Thomson is confident that Osprey will survive the gales.
David Elliott, head of the technical policy group at Britain's Open University, is also an enthusiast of the project. He recalls that from 1974 to 1982, the British government spent $23.83 million investigating wave power. Elliott says the emphasis was on large-scale generators well out to sea.
The government concluded that the technology involved was too complex and costly. "Since then, it has shown zero interest in wave power," Elliott says. "The government's focus should have been on smaller, low-cost projects" such as Osprey, he argues.
Elliot points out that the Osprey is very portable. "An individual device can simply be towed to the site where it is needed and its ballast tanks filled to lower it to the sea bed. "When its work there is completed, the ballast can be removed and Osprey refloated and towed to another site."
"Arrays" of Ospreys could even be put in position and their total generating capacity tapped for use onshore. "If you really need electricity and have no other easily available alternative, you will find Osprey an ideal energy source," he says.
Countries in northerly and southerly latitudes seem best suited to the application because they have the largest ocean swells. "You need about 500 miles of open sea to make it work," Thomson says. "America, Africa, Australia, New Zealand and other Pacific countries offer the best prospects."
Osprey's simple construction and operation, Thomson says, could make it ideal for Third World countries. It will appeal to governments keen to avoid depleting the Earth's resources or causing irreparable damage to the environment. The environmental group Friends of the Earth in London supports Osprey, saying anything that promises to make renewable energy a continuing resource is to be applauded.
The addition of a wind-power attachment on top could double Osprey's generating capacity, Thomson says.
What ART still has to prove, Macdonald says, is that Osprey is capable of producing electricity economically.
One thing is not in question: There is a huge amount of energy locked up in the oceans. Britain's Department of Energy estimates the country's total theoretically usable wave energy is 12 gigawatts - roughly equal to Scotland's power supply. Worldwide, the total exploitable wave energy resource is conservatively estimated at 400 gigawatts.