A Severn Barrage with the potential to generate around 7% of the UK’s energy needs has been ruled out by an independent commission which instead is recommending over the long-term a series of commercially viable tidal lagoons.

Last year the cross-border Western Gateway Partnership set up an independent commission to assess the potential for renewable projects in the Severn Estuary.

The final report from the Severn Estuary Commission said a barrage, that would create reliable and clean energy from one of the world’s highest tidal ranges, should not be pursued at this stage, due to its environmental impact, legislative challenges and disruption to ports, such as Bristol, and other commercial activities.

Rather than a tidal barrage, for which there have been numerous proposals over the years, it says that a series of commercial tidal lagoons could be developed - although at this stage not specifying any numbers or potential locations.

The commission said the focus should be on an initial commercially viable demonstration tidal lagoon project, which depending on its scale could range in cost from £2bn to £40bn. It said it would also provide environmental monitoring to help shape any further lagoon projects.

With UK electricity demand set to more than double by 2050, the commission have called for urgent investment for what they said could be the last opportunity to realise the clean tidal energy potential of the Severn Estuary. It is calling on the UK and Welsh governments to align their policies underpinned by a tidal range energy national (UK) policy statement, which it said would further establish clear policy backing, confirm government commitment, enhance investor confidence and enable public sector investment in environmental research and monitoring.

The commission, chaired by Dr Andrew Garrad, a leading pioneer of the modern wind energy industry, spent a year engaging with more than 500 individuals and over 200 organisations, to gauge the potential for finally harnessing the power of the UK’s largest tidal range following proposals going back decades.

Plans for the £1.3n Swansea Bay Tidal Lagoon were rejected by the then UK Government of Theresa May in 2018 on a value for money assessment with regards to the required contract for difference subsidy. The company behind what would have been effectively a proof of concept lagoon, Tidal Lagoon Power, planned a series of larger lagoons in the estuary, including one off the coast of Cardiff.

The commission’s report calls for the use of the regulated asset base (RAB) financing model to help de-risk the construction phase of the demonstration project. This would see investors receiving a guaranteed return on investment for the lifetime of the lagoon, with the cost recovered through energy prices charged to consumers. The RAB finance model was used to fund construction of the Thames Tideway Tunnel and is being proposed for the planned Sizewell C nuclear power station project.

The report from the commission, consisting of nationally and internationally recognised engineers, financiers, scientists and other experts, also recommends that:

  • Both the UK and Welsh Government back the development of a commercially viable demonstration tidal lagoon in the Severn Estuary, which if successful would pave the way for further projects securing economic growth and long-term energy resilience and making the UK a global hub for tidal range energy:
  • Improving cross-border working and planning to ensure any new development can be strategically delivered to ensure best outcomes for the area; and
  • A public sector led initial development approach and the establishment a project delivery vehicle using existing organisations.

Dr Garrad said: “This last year has been an eye-opening experience for all of us on the commission, understanding the huge potential of this source of renewable energy and also the international environmental importance of the estuary. Indeed, what sets this commission aside from previous studies is the emphasis that it has placed on the environment.

“Electricity demand will increase with the widespread uptake of electric vehicles, electrification of heating, industry and proliferation of data centres. We urgently need to get serious about how we can make use of our natural resources to meet this demand whilst also tackling our carbon emissions.

“Given the likely timelines for developing a project of this scale, we need to act now to ensure we can deliver the energy when it is needed and at the same time safeguard the environment.”

At this stage the commission has not given a figure on the level of energy output potential for a demonstration lagoon or any further projects, but that it would be be significant.

Welsh Cabinet Secretary for Economy, Energy and Planning, Rebecca Evans said: “We want to make Wales a world centre for emerging tidal technologies, and the Severn Estuary is a source of immense potential energy as one of the highest tidal ranges in the world. I welcome the work of the Severn Estuary Commission and I look forward to working with the UK Government and the Western Gateway to make sure that we can harness its potential whilst also protecting this unique asset.”

Sarah Williams-Gardener, chair of the Western Gateway, said: “After many years of debate, we now know that the huge potential of tidal energy in the Severn can and should play a key part in our energy supply.

“We need urgent action to make the most of this opportunity. A lagoon project (demonstration) could not only deliver predictable renewable energy, it could also add up to £12bn gross value added to the UK economy and 220,000 job years in the construction phase.

“I am very grateful to the work of this commission to explore this huge opportunity for the UK. On behalf of our board of local authorities, I look forward to working with both UK and Welsh Government to make this a reality.”

The Western Gateway Partnership, which is backed by local authorities and the private and education sector from Carmarthenshire to Swindon, was established to champion the economies and investment potential of south Wales and the west of England.

It is now facing the loss of its key funding contribution of £1m a year from the UK Government. However, the partnership said that its stakeholders are committed to backing efforts to realise commercially viable tidal lagoon energy generation in the estuary.