Hydro has named the concept turbine Hywind, saying it hopes to be able to develop wind farms able to harness the wind at its full strength – out at sea.

The company has been testing the model at a Norwegian research and development institute, Sintek Marintek, using data collected from the Trondheim ocean basin over 30 years to simulate the wave and wind conditions Hywind is likely to experience.

Deep-sea wind farming had been considered unfeasible due to the difficulty in securing the turbine.

Hydro's long experience in the oil and gas industries, particularly in the North Sea, led them to explore the potential of a floating windmill secured to the ocean floor with the same technology used for deep-sea platforms.

Although trials are continuing, the company announced last week that it was proposing to test the technology in deep water off the Norwegian west coast.

"Deep waters close to land, as well the proximity of established shipyards and supplier industries, make the sea off Karmoy on the west coast of Norway the perfect location for the world's first floating windmill," said the head of Hydro's New Energy unit, Alexandra Bech Gjorv.

Bech Gjorv said a key advantage of the proposed site was the ability to test the Hywind project in deep waters that were visible from the shoreline, simplifying the logistics of any maintenance or inspections required during the research demonstration.

The demonstration 3MW Hywind turbine is 200m long – 120m of which will be submerged. Its tip-to-tip rotor diameter is about 90m.

Depending on the success of the demonstration, Hydro intends to build 5MW Hywind turbines with a rotor diameter of up to 120m.

"The future goal is to have large-scale offshore wind parks with up to 200 turbines capable of producing up to 4 terawatt hours per year and delivering renewable electricity to both offshore and onshore activities," Bech Gjorv said.

Hydro estimated 4TWh was enough energy to power 200,000 typical Norwegian households.

"This goal is far in the future, but if we're to succeed in 10-15 years, we have to start the work today," she said.

The 3MW demonstration Hywind is expected to be operational some time in 2007.