SURROUNDED by strong seas and winds, Scotland has 25 per cent of Europe's tidal resources and 10 per cent of its wave potential.

One of the biggest energy suppliers - ScottishPower Renewables - wants to convert that natural power into clean electricity, with banks of gigantic, high-tech underwater turbines turning the sea's tidal movement into green energy.

It is developing a system that will be the largest demonstration tidal power project in the world, putting the company at the forefront of similar tidal power developers globally.

By building at least 40 underwater turbines in various places off the Scottish coast, the tidal farm sites would have a combined output of 60 megawatt (MW), enough to power 40,000 homes in Scotland and Northern Ireland.

It is thought that, if fully accessed, Scotland's tidal resources could contribute to more than 30 per cent of its energy demand. One of the benefits of tidal power is that it is extremely predictable compared with other forms of green energy.

Experts believe that thousands of jobs could be created in this sector as the technology is exported across the world, with an estimated market of some 40 billion pounds.

Scotland's government recently stated: "... kick-starting the sector is vital if we are to create a significant industry based in Scotland and meet our long-term renewables targets."

The high-tech underwater turbines are 30 metres tall and can work as deep as 100m. The 20m blades would turn at least 10m below the surface to avoid shipping; the energy zones would be off-limits to trawlers for safety reasons.

According to Keith Anderson, the director of Scottish Power Renewables, "Tidal power is completely renewable, being driven by the gravity of the sun and moon, with no carbon dioxide emissions, plus the added benefit of being entirely predictable.

"The rapid technological advance of tidal power has been startling and is now allowing us to progress plans for substantial projects delivering major environmental and economic benefits," he added.

ScottishPower Renewables' partner in the scheme is Hammerfest Strøm UK, a subsidiary of the Norwegian tidal power developer Hammerfest Strøm.

Hammerfest has received a grant of 3.9m pounds from the UK's Carbon Trust for the construction and testing of a 1MW tidal power device off the Orkney islands, northern Scotland.

Hammerfest Strøm's underwater turbines are mounted on the sea bed to capture "tidal stream" power, different to "tidal barrage" power, because there is no need to impound the water.

This is expected to bring significant environmental advantages by avoiding impacts on sensitive inter-tidal zones around coasts. In the future, arrays of multiple devices are anticipated that could each generate 50-100MW.

The tidal turbine is expected to be fully operational near Orkney by 2011. Hammerfest Strøm UK has already completed the design and pre-engineering and is now tendering for fabrication and installation.

After a test period, the company will work with ScottishPower Renewables that has plans to install the device as part of a 10MW tidal power array off the coast of Islay, south-west Scotland, by 2012.

Hammerfest Strøm's device is designed based on a 300kW prototype that has been installed in Kvalsundet, Norway, for the last six years. The prototype device was the first turbine in the world to convert kinetic energy in tidal waters to electricity and deliver to the grid in 2004.

ScottishPower's Keith Anderson added: "We firmly believe that the tidal turbine developed by Hammerfest Strøm is the most advanced and rigorously tested device anywhere in the world.

"The grant from the Carbon Trust will enable the first deployment of the turbine in Scottish waters, where we have ambitious plans to further utilise the device at a number of locations to take advantage of the fantastic tidal resources that Scotland has to offer."

The tidal power resource is estimated at some 150 billion kilowatt-hour per year globally (representing capital investment of about 40bn pounds sterling). The UK share has been estimated at 13 bn kilowatt-hour and more than 80 per cent of this is located in Scottish waters.

ScottishPower Renewables is part of Iberdrola Renovables, a Spanish multinational corporation, that is the largest wind energy company in the world with an installed capacity of almost 11,000MW at the end of 2009, and a pipeline of 57,400MW. ScottishPower Renewables had more than 800MW of installed capacity at the end of 2009, and a pipeline of 5,115MW.

Image: Waves of energy: a Scottish company wants to convert the huge natural power of the sea into clean electricity, with banks of super high-tech, underwater turbines turning the sea's tidal movement into green energy. Image by Scottish Power Limited