£1.3bn plan is seen as ‘pathfinder’ for six bigger plants, which could generate more than 10% of UK’s electricity

Plans for a pioneering tidal power lagoon in Swansea Bay are expected to be supported by a government-commissioned report this week, potentially unlocking a multibillion-pound series of projects harnessing electricity from the rise and fall of the tide around the UK.

When ministers last year ordered a review to see if the technology could affordably provide green energy to the UK, it was widely seen as a way to kill off an ambitious project at Swansea proposed by Tidal Lagoon Power.

But when the independent review by former energy minister Charles Hendry is published on Thursday, sources told the Guardian it will be broadly positive towards the £1.3bn prototype plan.

Swansea is seen as the “pathfinder” ahead of five major plants around the country, at Cardiff, Newport, Colwyn Bay in north Wales, the Cumbrian coast and Bridgwater Bay in Somerset. Together they could provide about a tenth of the UK’s electricity needs and help meet carbon targets.

Hendry has visited communities which would potentially be involved in or affected by the lagoons, which he said had attracted “high expectations”.



Tidal Lagoon Power has spent £35m on the Swansea project, which would see a U-shaped breakwater built across the bay and the incoming and outgoing tide passing through 16 turbines, generating enough power to supply 150,000 homes with electricity.



But the developer and government officials have not yet been able to reach agreement on a guaranteed price for electricity from the lagoon. Negotiations are continuing on a price that would be even higher than the one agreed for the new Hinkley Point C nuclear power station, and paid for by a levy on energy bills.

Shortly before the tidal review was commissioned in February 2016, the then prime minister, David Cameron, said his enthusiasm had been reduced because of fear of high costs.

Ben Caldecott, associate fellow at the liberal conservative thinktank Bright Blue, said: “The key thing is for tidal to demonstrate it can be a cost-competitive renewable technology without subsidy – if not today, then soon. Other renewable technologies have achieved this.”

Mark Elborne, president of General Electric UK, which is linking up with Tidal Lagoon Power to provide the generators in the Swansea turbines, said the government should take the long view on the technology.

“On the face of it some might say the cost per megawatt hour for Swansea Bay looks pricey. However, even as a one-off project the fact that it is only partially index-linked means it already comes in cheaper than Hinkley’s £92.50 per MWh. But the point is it is cannot and should not be seen as a one-off project, because it is not,” he said.

He added: “Swansea is a prototype for a series of much bigger lagoons across the UK. Because bigger lagoons are able to pass far greater volumes of water through their turbines they are guaranteed to generate far cheaper power.”

The company believes that if the six projects were completed at scale, they could together provide 12% of the UK’s electricity for about the same subsidy as onshore wind or solar power today.

Mike McNicholas, managing director of the infrastructure division at Atkins, another partner in the Swansea scheme, said tidal lagoons could demonstrate the UK was still capable of the sort of engineering ingenuity seen in the Victorian era.

“As an island, tidal lagoons are a game-changing solution for harnessing our most reliable and abundant natural asset – the tide.”

Industry also thinks that prospects for tidal power are rosier under a new ministerial team at the Department for Business of Energy and Industrial Strategy, and in the light of government backing for Hinkley and a third runway at Heathrow.

The Hendry review and government declined to comment.

