Plugging in the giant generator that is our seas

WHIPPED up white and spitting salty spray, the waves that crash against our coastline are charged with hidden energy. Driven by winds and currents across thousands of miles of the Atlantic, they pound beaches and cliffs with enough raw power per foot for 100 homes.

This is a giant generator waiting to be tapped, one rivalled only by Chile and Australia for its potential to produce more than three times our annual power requirements. The question is: how do we turn it on? And what will be the environmental cost?

Next year, at Billiacroo Bay, near Stromness in the Orkney Islands, a quiet stretch of water facing the open Atlantic, four giant metal "sausages", each 520ft long will be towed 2km offshore, where they will float, quietly harvesting the waves. The "Pelamis" generators, named after a type of sea-snake, bob up and down with the action of the water pushing hydraulic rams into a generator, which, in turn pressurises oil that is used to drive a turbine.

The £25 million wave-power farm will, in time, be the world's largest and is expected to generate 3MW of electricity by 2010, enough to power 3,000 homes on the Orkney Islands.

ScottishPower hopes that by 2020 the farm could expand to produce 600MW a year.

The power company is working with Ocean Power Delivery, the Edinburgh firm that devised the Pelamis, and the European Marine Energy Centre, which is monitoring what is largely an experiment. While the Pelamis is among the most advanced of such projects, it will not be the only generator in the sea.

Earlier this year the Scottish Government, or Executive as it then was, invested £13 million in the development of eight systems designed to generate electricity from the seas. There is genuine hope that Scotland could become the marine renewables capital of the world and grab a major slice of a market potentially worth billions of pounds.

Nicol Stephen, the former deputy first minister, said: "This is as significant for Scotland's future and arguably more significant for the planet's future than the discovery of North Sea oil."

Yet as Neil Kermode, managing director of the European Marine Energy Centre at Stromness, which is trialling three of the systems, explained: "We're at the early stages and we need to discover what systems work best. If you compare us to the aviation industry, we're still at the Wright brothers stage."

While the Pelamis floats on the surface there are also plans to sink into the deep to harvest tidal currents, deemed the most reliable form of marine energy.

In ten years' time if you were to sink down into the deep blue waters of the Pentland Firth, the narrow channel between the mainland and Orkney, Scottish Power hopes you would see a forest of as many as 1,000 sunken "windmills", generators fixed to the sea bed and rising up 30m as they collect energy from the fast-flowing tidal stream.

The company believes as much as 1,000MW could be collected from the Firth and is in partnership with a Norwegian company which has pioneered the generators in Fjords.

Alan Mortimer, head of renewables development at ScottishPower, said: "What is really exciting abut this site is that its completely predictable."

Given the nutrients stirred up by the strong currents and the whales these attract, it could also be classified as a nationally important marine area and there may be concerns about the creation of an obstacle course of sunken steel pillars.

Yet Mr Mortimer believes that with careful negotiation everyone will benefit.

"If it is handled sensibly there should not be too much overlap with ecologically sensitive areas. We think conflict can be avoided," he said.

It is a sentiment shared by Jason Ormiston, chief executive of Scottish Renewables, who said it was important for the industry to continue to conduct research into the effects of new machinery on the environment and wildlife. He said: "We are still a long way from any large-scale implementation, but any wave or tidal farms will be subject to strict scrutiny and environmental impact studies."

Yet applying untested technology means dipping a toe into uncharted waters.

Ian Boyd of the sea mammal research unit at St Andrews University explained: "There is considerable uncertainty about how offshore wind, tide and wave farms might affect marine wildlife, and this presents us with some important challenges and ethical dilemmas.

"Development needs to go hand-in-hand with adaptation of the designs and approaches. It is likely that much marine wildlife will not be affected significantly but some, like marine mammals, could be sensitive to some types of development.

"We need to be prepared to treat these developments as experiments and ready to make the tough decision that some approaches might not work from an environmental perspective."

FROM WAVES TO WATTS

IN THE Western Isles, another means of harnessing wave power is to be trialled.

Npower Renewables wishes to install a giant concrete "Limpet" to an excavated rock face at Barvas, on the coastline west of Stornoway.

The movement of waves is used to push air in and out of a concrete chamber. This air is passed through a turbine to generate electricity. Npower has applied for planning permission and hopes to generate four megawatts a year by the end of 2010.