A £12bn scheme to build a series of tidal energy plants in Britain will be kickstarted on Friday as a planning application is submitted for the world's largest power-generating lagoon in South Wales.
The promoters want to follow up an initial £850m project for Swansea Bay with four even larger lagoons with a capacity of 7,300MW – enough to meet 10% of the UK's electricity needs.
Tidal Lagoon Power has put in a development consent order under the Planning Act 2008, but must convince the government to provide subsidies of £156 per MWh – even more than that going to offshore wind farms.
The project must also overcome scepticism about tidal power following the collapse of the much-larger Severn Barrage power generator in the same region.
"Our intention is to supply 10% of the UK's domestic electricity by building at least five full-scale tidal lagoons in UK waters by 2023, before the UK sees any generation from new nuclear," said Mark Shorrock, chief executive of Tidal Lagoon Power, who has launched successful wind and solar schemes.
The project, which envisages an area of 11.5 sq km cordoned off by a breakwater, would have an installed capacity of 320MW with an annual output of 420GWh and a design life of 120 years.
A 9.5km sea wall up to 20m high would need to be built, but Shorrock says only a little over half of this wall would be visible from the land at low tide, and barely a few metres showing at high tide.
The power will be generated as the incoming and outgoing tides – the daily equivalent of 100,000 Olympic swimming pools worth of water – pass through turbines.
Shorrock it was essential to build more than one tidal lagoon: "Economies of scale bring immediate advantage. A second lagoon will require a lower level of support than offshore wind, for a renewable power supply that is both long-lived and certain.
"A third lagoon will be competitive with the support received by new nuclear, but comes without the decommissioning costs and safety concerns," he added.
The second project would cost £2.3bn and be based in Colwyn Bay, with a third costing £4bn located in the upper Severn estuary. Two more at a cost of £4.5bn would follow, on as-yet-unspecified sites.
Shorrock, who has already constructed 280MW of wind and solar plants, says he has potential financial backing from the Macquarie Group's infrastructure funds and would like to bring in UK pension funds as investors.
He says the projects would be far cheaper and more productive than the £30bn Severn Barrage scheme which was first turned down by the government in 2010 amid huge opposition from many environmentalists.
The renewable energy entrepreneur says he has support from the local community and leading green activists for the Swansea Bay tidal lagoon, which as well as providing light and warmth for 120,000 local homes could also become a centre for sailing and other recreation.
Sean Christian, special sites spokesman for the bird and wildlife lobby RSPB, said he welcomed the fact that energy projects in the Severn estuary were now focused on tidal power lagoons rather than the more damaging shore-to-shore barrages.
"This technology will have less impact on fish and other wildlife than the barrage proposals, which conservationists have spent several years fighting in the estuary, and which the government has repeatedly rejected.
"However, it could still have major impacts on the estuary and its wildlife, and we will need to look at the details of each lagoon proposal closely. "
Tidal Lagoon Power has already built a potential team of British-based suppliers who would help with the scheme, including Alstom, Sheffield Forgemasters and Atkins. The equivalent of 1,850 full-time jobs are promised in the construction phase.
David Tonkin, chief executive for the UK and Europe at the engineering company Atkins, said: "The tidal lagoon concept represents a bold new addition to the energy mix. It is a great example of how innovative engineering could be used to harness our natural resources and provide clean, sustainable and predictable power for thousands of homes.
If given the go-ahead for planning and the subsidies, construction of the Swansea Bay lagoon is slated to begin in the first half of next year, with the first power being generated in 2018.
It would also be a major boost to local employment opportunities, especially while it is being constructed. Ian Isaac, who runs NSA Afan, a community-based regeneration organisation, said: "Swansea Bay tidal lagoon will be the first of its kind in the world and will make a statement for vision of future Welsh industry. Importantly, it will be an innovative approach to tackling high levels of unemployment in the area."
• This article was amended on 7 February 2014. Editing errors led to the earlier version referring to MW/h and GW/h instead of MWh and GWh.
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