Renewable Energy in Scotland - Tidal Power

Tidal Power

Unlike wind and wave, tidal power is an inherently predictable source. However the technology is in its infancy and numerous devices are in the prototype stages. Today it is known that a tall tubular tower with three blades attached to it is the typical profile of a wind turbine, but twenty-five years ago there were a wide variety of different systems being tested. This is the current situation with regard to tidal power. Some systems capture energy from the tides in a vertical direction. The tide comes in and raises the water level in a basin. As the tide lowers the water in the basin is discharged through a turbine. Tidal stream power captures energy from the flow of tides, usually using underwater plant resembling a small wind turbine. An example is Marine Current Turbines SeaGen 1.2 MW device at Strangford Lough in Northern Ireland, which is the largest tidal stream turbine in the world. To date the only installed tidal power plant of any size is the 240 MW rated barrage scheme at the Rance Estuary in Brittany, which has been operating successfully for more than 25 years, although there are a number of other much smaller projects around the world.

The Pentland Firth between Orkney and mainland Scotland has been described as the "Saudi Arabia of tidal power" and may be capable of generating up to 10 GW. In March 2010 a total of ten sites in the area, capable of providing an installed capacity of 1.2 GW of tidal and wave generation were leased out by the Crown Estates. Several other tidal sites with considerable potential exist in the Orkney archipelago. Tidal races on the west coast at Kylerhea between Skye and Lochalsh, the Grey Dog north of Scarba, the Dorus Mòr off Crinan and the Gulf of Corryvreckan also offer significant prospects.

In August 2010 the Atlantis Resources Corporation 's AK-1000 turbine, which has 18 metres (59 ft) blades was unveiled at Invergordon. It is claimed to be the largest tidal turbine ever built and will be tested by EMEC off Eday. In October 2010 MeyGen, a consortium of Morgan Stanley, Atlantis Resources Corporation and International Power, received a 25 year operational lease from the Crown Estate for a 400MW tidal power project in the Pentland Firth. However in 2011 the plans were in difficulty after Norwegian partners Statkraft pulled out of the project.

In 2010 it was announced that 10 Hammerfest Strom HS1000 Norwegian turbines, capable of generating 1 MW each, could be installed in the Sound of Islay and that the BiFab yard at Arnish had won a £2 million contract to build some of the structures' components. The following March this project, which will become largest tidal array in the world, was approved by the Scottish Government with 10 planned tidal turbines predicted to generate enough power for over 5,000 homes. It will be located off the west coast in the Sound of Islay which offers both high currents and shelter from storms. A single 1MW HS1000 was installed at EMEC off Eday, Orkney by the end of 2011.

The "world's first community-owned tidal power generator" is planned for Bluemull Sound in Shetland. This 30 kW Nova Innovation device is expected to be operational by the end of 2011. At the opposite end of the country a consultants' report into the possibility of a scheme involving the construction of a Solway Barrage, possibly south of Annan, concluded that the plans "would be expensive and environmentally sensitive."