It would be one of the biggest projects of its kind, perhaps since the fens themselves were drained. But would a proposed tidal barrage across the Wash protect us from climate change, or further harm the environment? CHRIS BISHOP reports
First dreamed up in the 1960s, proposals to build a hydroelectric barrage across the Wash have resurfaced from its muddy waters. And this time they seem to have a rising tide beneath them.
Port Evo, the company behind the Centre Port plan, says the structure could generate enough electricity to power 600,000 homes, protect low-lying areas from flooding and bring a new deep-sea container port which would boost the economy.
It has been quietly canvassing politicians, landowners including the King's Sandringham Estate, Whitehall departments and businesses.
The message was simple, according to one local councillor who joined a Zoom call: Sooner or later, we are going to have to do this.
"I think they're right, you know," he said afterwards. "I think they should just get on and start building it."
Proposals for a similar barrage were abandoned soon after they were unveiled in 2008.
Almost 15 years later, the logic is stark and straightforward. Climate change is accelerating, along with rising sea levels.
Parts of the Fens - which were drained centuries ago - are 5m or more below sea level and, along with coastal towns like King's Lynn and Boston, will become increasingly vulnerable as North Sea storm surges become more frequent and extreme.
Port Evo says the 11-mile-long barrage, stretching from Hunstanton to Skegness, could be the historic Hanseatic ports' salvation.
But while a barrage might tick a lot of boxes, those behind it will have to swim against a strong tide of opposition - and overcome government reluctance to bankroll similar schemes.
Conservationists, from the Wash-side farm which hosts the BBC's flagship Springwatch nature programme to powerful voices like the RSPB and Norfolk Wildlife Trust, are all singing from the same song sheet.
While Centre Port insists its plans will ultimately protect the internationally-important Wash and its wildlife, naturalists fear they will have "catastrophic impacts" on them.
Now the National Trust, another big hitter in the conservation stakes, has labelled the barrage "deeply concerning".
Victoria Egen, its general manager for the Norfolk coast, said: "We know that nature is already close to breaking point, and we should be doing all that we can to protect it.
“The Wash is one of the most important estuaries in the UK. Straddling Lincolnshire and Norfolk, the area’s vast salt marshes and mudflats are an important site for migratory, over-wintering and breeding wetland birds.
"Climate change is the biggest threat we all face, and we acknowledge the need for green energy. However, this has to be done in the right place and in the right way, so that it doesn’t impact what we’re ultimately trying to save."
Sam Owen, director of Port Evo, said: "Our mission statement is to save the Wash from climate change impacts.
"These could easily overtop the existing sea defences with catastrophic impacts on the Fens. A breach at King's Lynn on the Great Ouse could see a tide of water running downhill to Cambridge.
"A detailed study of the Wash and its sea life will be undertaken as part of the feasibility study.
"The turbines are fish-friendly and a sea lock will be open at low and high tides to facilitate access for seals and marine life."
Power firm Centrica has invested a five-figure sum in the feasibility study, which will cost £2m.
Greg McKenna, its managing director, said: “We’re excited to help Centre Port explore their ambitious plans for the Wash.
"The project represents one of the largest tidal power schemes anywhere in the world and would provide a reliable source of green energy to the UK.
"The first step is to understand the role such a scheme would play in an area of the country particularly vulnerable to the effects of climate change.”
As energy supply security creeps up the political agenda, proposals for a tidal barrage across the Severn Estuary, between South Wales and Somerset, are also back on the agenda.
The scheme was shelved after a decade of debate in 2013, after the House of Commons Energy and Climate Change Committee concluded that the project "has not demonstrated sufficient value as a low-carbon energy source to override regional and environmental concerns".
Those concerns included its impact on Atlantic salmon and shad, a threatened migratory fish which run up the Severn to spawn, along with birds.
Now a new panel of experts has been formed by Cardiff council, to assess whether technology and political will have moved on.
A £1.3bn hydroelectric scheme proposed for Swansea Bay was given planning permission in 2015.
But that barrage was abandoned in 2018 after the government refused to provide financial support to guarantee the price developers would receive for its electricity.
Industry experts say harnessing the tides to generate electricity will require a more long-term view.
In June, industry journal Energy Monitor published a report into why the tidal power industry has stalled.
Roger Falconer, professor of water and environmental engineering at Cardiff University, explained: “You only need to invest in a few wind turbines or solar panels to get a return, but it will take five years to build a barrage or lagoon, involving a massive concrete pour and significant investment, and this is a lot for politicians to stomach."
Just three large-scale hydroelectric tidal barrages have ever been built. The first opened at La Rance, in Brittany, in 1966. It was followed by two similar schemes in South Korea.
La Rance is still generating power 60 years later, has paid for itself several times over and supplies cheaper electricity than France's bevy of nuclear power plants.
So the numbers can add up if you give them time.
Port Evo appears confident it can obtain the £2bn needed to build the barrage from investors - perhaps the most money that has been poured into the Wash since King John supposedly lost his treasure in its waters.
But the scheme's true environmental costs remain unknown, along with which side is right when it comes to safeguarding the future of the Wash.
And those are almost certainly the sums which will have to add up before a barrage ever happens.
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