A 30-meter- turbine anchored to the seafloor off the Scottish coast is proving that tidal farms are a turn closer to being a viable renewable energy source.
Scottish Power completed preliminary trials of the giant undersea turbine in the fast-flowing coastal waters off the Orkney Islands. It found that the turbine produced one megawatt of electricity, enough to power 500 homes and businesses.
"We're very pleased with the initial results and we've operated at full power already," says Alan Mortimer, head of innovation at Scottish Power Renewables.
If the next stage of testing goes according to plan, Mortimer says that work will soon begin on a fleet of the turbines -- manufactured by Norwegian company Andritz Hydro -- and will be installed at another site in the Sound of Islay off the west coast of Scotland.
Although there are examples of similar stand-alone operations in Norway and the UK, the Sound of Islay turbines would be the first large group of its kind anywhere in the world. When fully operational it is estimated to produce electricity for 5,000 homes.
Other countries with strong tidal resources and potential sites for tidal power farms include Argentina, Chile, the U.S. and Canada.
Compared to offshore wind farms, tidal energy devices like the turbine trialed in Scotland are completely hidden from view.
They are criticized for being potentially harmful to marine life, but Mortimer contends that because the turbine's propellers move relatively slowly, the impact on fish and other forms of sea life is minimal.
Scottish Power says that it already has planning consent and a lease for the seabed where the tidal farm will be built. However the main obstacle to the implementation of more tidal farms remains the cost.
"We have publicly stated that we expect the capital costs of the Islay project to be around £70 million ($110 million)," says Mortimer, which equates to roughly $11 million per turbine.
The 10 megawatts of power that will be generated by the Sound of Islay turbine farm pales into insignificance when compared to the output of a large nuclear or coal power station, which according to American hydro energy non-profit the Ocean Energy Council, can produce up to 100 times as much electricity.
Mortimer is quick to point out that he believes such challenges are inevitable in developing new technologies and that costs would fall and efficiencies improve as the fledgling industry develops.
"The estimate for the UK in terms of wave and tidal is that it could eventually produce in excess of 10% of the country's electricity requirements," says Mortimer. "That's definitely big enough to make it of interest for us to pursue it."