Six vast underwater turbines are to be lowered into the tidal currents of the Pentland firth in the first phase of one of the largest tidal energy schemes in Europe.
Permission to install the six squat machines, which look like underwater propellers, has been granted by Scottish ministers as a demonstration project to prove they work, with more than 50 of the machines eventually due to be installed on the seabed off Caithness.
The fast-moving waters off Scotland’s northern coasts and islands are seen as among the most valuable in the world for tidal and wave power, with Scottish ministers claiming there is enough capacity to replace three coal-fired power stations the size of the UK’s largest, at Drax in Yorkshire.
Approval for the scheme was applauded by environmentalists. Richard Dixon, director of Friends of the Earth Scotland, said it was great news for the renewable industry. “Harnessing the huge energy in the tides of the Pentland Firth is a major engineering challenge, but this scheme will prove technologies and techniques which will be important in future tidal energy schemes around the world,” he said.
Tidal energy has two main advantages over wind power: it is more predictable and it does not attract criticism from people who object to the visual impact of wind turbines on land. However, it is much more expensive because the technology is less developed.
The first phase of the project by MeyGen, a joint venture between the giant US investment bank Morgan Stanley, the French-owned energy firm International Power and the Australian turbine manufacturer Atlantis Resources Corporation, will generate up to 9MW to prove the technology works.
The consent granted by Fergus Ewing, the Scottish energy minister, will allow MeyGen to slowly enlarge the scheme to hit 86MW by the end of the decade, enough to power about 46,000 homes – about 40% of homes in the Highlands.
Ewing said: “We must tackle climate change. We need to reduce our reliance on fossil fuels through better and more efficient uses of energy. Marine energy – a homegrown technology with huge potential – is part of the solution.”
Environment campaigners said the decision increased pressure on ministers in both the UK and Scottish governments to support the industry by investing far more in the electricity grid and in financial support to help cut the considerably higher costs faced by renewables schemes in northern Scotland.
Lang Banks, director of the environment group WWF Scotland, said he was stunned by apparently dismissive remarks by Ed Davey, the UK energy and climate change secretary about the prospects of extra subsidies for northern tidal and wave schemes.
Davey announced at the Liberal Democrat conference that onshore windfarms on Orkney, Shetland and the Western Isles would get a higher guaranteed price for their electricity than onshore windfarms anywhere else in the UK, to help meet their higher costs.
But asked by the Guardian if the same subsidies would be given to wave and tidal projects and offshore wind developments in the same areas in future, he said no, and described the question as hypothetical.
Banks said that Davey was undermining confidence in the industry, coming on the same day that the Lib Dems agreed to billions of pounds of support for new nuclear power stations.
“It’s really, really important that governments give clear signals about what they want to do to build confidence in new renewable technologies. In the week Davey gave that support to nuclear power, it’s unacceptable that he’s not offering the same clear signals to real zero-carbon projects like wave and tidal,” Banks said.
The MeyGen scheme will be Europe’s largest tidal array project – a type of scheme where turbines are clustered across an area of seabed. Eventually MeyGen wants to dramatically expand it to 398MW, making it one of the world’s biggest renewables projects.
Until that much larger scheme gets permission from the Crown Estate and Scottish ministers, it will not be the largest of all Europe’s tidal power plants: the La Rance tidal barrage built across the Rance river in Brittany, northern France, nearly 40 years ago has a peak rating of 240MW from its 24 turbines.