The Swansea Bay Tidal Lagoon is “hideously expensive” and offshore versions of the technology could provide power at a quarter of the price.
That’s according to Dale Vince, the founder and CEO of UK renewable energy firm Ecotricity, who has called on the government to resist pressure to back the £1.3 billion facility.
Mr Vince claims Tidal Lagoon Power’s proposed facility in Wales could see energy bill payers overcharged by billions of pounds for the next 100 years.
He said similar facilities based offshore could cost as little as £90 per megawatt hour for 25 years rather than £90 per megawatt hour for 90 years as is currently proposed for Swansea Bay.
Ofgem has said tidal lagoons like Swansea are “more about their potential role in facilitating regional regeneration” than producing power and the cost should not be added to national energy bills.
Mr Vince believes the site could damage wildlife and the environment, killing 25% of sea fish and salmon in the area and using rocks from protected regions in its construction.
He said: “Our new report shows that tidal energy shouldn’t be pursued at the cost that the backers of Swansea Bay are proposing.
“Done properly, tidal lagoons can provide power at almost a quarter of the cost of this proposal and lower than the cost of nuclear.”
A spokesperson from Tidal Lagoon Power told ELN: “Swansea Bay Tidal Lagoon is the pathfinder for a new global industry that can pull down the price of electricity for consumers while allowing them to interact with and learn from the source of that electricity like never before.
“Investors want to fund tidal lagoons, British industry wants to supply them, coastal communities want to host them and with permission to proceed from UK Government we can be on site in Swansea Bay next year.”
Ecotricity has recently launched a bid for seats on the board of rival firm Good Energy.