An underwater turbine destined to form part of a major green energy project is already using tidal power to produce electricity for homes on a remote Scottish island.
The 100ft-long device, which can provide enough energy to meet the electricity needs of 500 homes for a year, has completed its initial testing period.
Bosses at ScottishPower Renewables said the results gave them "great confidence" in the turbine which will be installed in the world's first tidal turbine array in the waters off Islay, in the west of Scotland.
The one-megawatt turbine was installed in the sea off Orkney last December in some of the worst weather experienced for more than decade. It is already providing power for homes and businesses on Eday, one of Orkney's northern isles.
ScottishPower Renewables plan to use the device in a 10-megawatt tidal array in the Sound of Islay. The firm received planning permission from the Scottish Government for it last year and it is hoped work can start next year and be completed by 2015.
Keith Anderson, chief executive of ScottishPower Renewables, said: "The concept of generating electricity from the natural movement of the tide is still relatively new - and test projects like this are vital to help us understand how we can fully realise the potential of this substantial energy source."
The performance of the turbine "has given us great confidence so far", he said.
"Engineers were able to install the device during atrocious weather conditions, and it has been operating to a very high standard ever since.
"We have already greatly developed our understanding of tidal power generation, and this gives us confidence ahead of implementing larger-scale projects in Islay and the Pentland Firth."
Mr Anderson went on: "Scotland has the best tidal power resources in Europe and that's why we are seeing world leading technologies tested here.
"This device is already providing renewable electricity for Orkney but the potential is there in our waters to make a significant contribution towards our overall energy needs and our carbon reduction targets."
The HS1000 tidal turbine has been developed by Andritz Hydro Hammerfest which is based in both Norway and Glasgow.
Managing director Stein Atle Andersen said the device is "an important step in our staged strategy for developing reliable and cost-efficient tidal energy converting devices and power plants".
Tests had "given comfort, concerning the device's capacity", he said.
"We are still early in the testing programme, with endurance, availability and reliability being the most imminent factors for asserting a proper basis for developing commercial tidal energy power plants. However, we are already well into design engineering for the first power plant."
WWF Scotland director Richard Dixon, said: "It's great news that this underwater turbine has not only successfully completed its initial testing phase but also been able to provide electricity for homes and businesses on the island.
"This news represents another step forward for the marine renewable industry in Scotland. There is a massive amount of power in our seas and Scotland is well placed to lead in developing the technologies to turn this potential into clean, green electricity.
"Alongside energy-saving measures, wave and tidal energy have a critical role to play in meeting the Government commitment to decarbonise our power supply by 2030.
"Given the huge renewable energy potential around our coast, and the strong skills in offshore engineering, marine energy offers a fantastic opportunity for Scotland.
"With careful planning, we can harness wave and tidal energy to help cut our climate emissions while safeguarding the nation's tremendous marine environment."
CORRECTION: The headline previously implied that the turbines have been installed at Islay, however, they will be installed at Islay in the future.