Revisiting the Case for Tidal Energy on the Severn in three Parts:
- The Severn Estuary Commission’s new Report.
- Tidal Energy on the Severn vs. Nuclear Power.
- The RSPB: Irretrievably Stuck in the Mud.
Part 1: The Seven Estuary Commission’s new Report
Over the years, I’ve been hugely critical of what I call the ‘all of the above’ brigade – made-up largely of nuclear enthusiasts who don’t want to be seen trashing renewables in public but are desperate to keep new nuclear (both big and small) in the mix to meet future electricity demand here in the UK – even though it’s abundantly clear that nuclear cannot compete with renewables on cost, construction time or even reliability.
We now have a wonderful opportunity to do a properly rigorous analysis of ‘nuclear vs renewables’ – this time, with the focus on tidal energy rather than wind or solar as is usually the case.
On March the 19th, the Severn Estuary Commission published its final ‘Report and Recommendations’ on the potential to develop tidal energy in the Severn Estuary. Set up by the Western Gateway Partnership (made up of 28 Local Authorities on both sides of the Estuary plus other key stakeholders), the Commission has handsomely met the brief it was given: review the historical record; don’t get lost in the weeds; tell us what tidal energy from the Severn can deliver, by when, at what sort of cost, for the region and for the UK as a whole; and what needs to happen next.
(You can check out the Commission’s report here: https://www.severncommission.co.uk/final-recommendations/)
This is a big moment for tidal energy in the UK. People have been talking about the extraordinarily exciting prospects for tidal on the Severn for more than 100 years, yet nothing has ever happened, with every proposal killed off by a combination of vested interests, political indifference, intransigent opposition from misguided environmental organisations (particularly the RSPB: see Part 3), and a shocking lack of vision.
And that lack of vision might just have something to do with the realisation (amply confirmed by the Commission’s report) that if the UK Government ever got serious about tidal power on the Severn, we’d finally be able to consign the nuclear industry’s ‘all of the above’ PR narrative to the dustbin – and with it, the monstrosity of Sizewell C (see Part 2).
But let’s just double back for a moment to the Commission’s principal recommendations – including, regrettably, that now is not the time to be pushing for a large-scale barrage on the Severn. In their opinion, a barrage would be too costly and too vulnerable to an unholy combination of NGOs (who genuinely do care a lot about the environment and climate change) and the powerful commercial interests of Bristol Port (who really do not, and are only too happy to be associated with the climate-denying lobbying of the Global Warming Policy Foundation and its ilk). Odd bedfellows, but I can understand why the Commission decided not to take them on.
Instead, the Commissioners have enthusiastically recommended that the UK Government should urgently find ways of supporting the potential for tidal lagoons in the Estuary rather than a full barrage – notionally with a far lower impact on the environment and therefore much more ‘NGO friendly.’
When the Sustainable Development Commission (which I was Chair of at the time) looked at the same combination of factors in its ‘Turning the Tide’ report in 2007), we seriously considered going down the same road in our recommendations to the Department of Energy and Climate Change (DECC). In the end, we decided that would be a deeply compromised copout: if a barrage is the best way of securing the Severn’s astonishing potential for cost-effective, predictable, environment-enriching tidal energy, over the next 120 to 150 years, then we concluded we had to go for it.
I don’t want to be too critical of the Severn Estuary Commission in revisiting the same dilemma. It’s well-judged enthusiasm and well-argued case for urgently prioritising investment in the Severn’s tidal resource is timely and very welcome. With the powerful support of the Crown Estate (a critical partner in this process, and the critical partner in any future delivery strategy), as well as the Western Gateway Partnership for as long as it’s still around, it will not be possible for Ed Miliband as Secretary of State at the Department for Energy Security (DESNZ) and Net Zero to kick this into the long grass.
That, however, will still be his senior civil servants’ favoured option. Just as it was back in 2010 when the Government’s Severn Tidal Power Feasibility Study relied on wholly inadequate ecological data to flag up ‘insuperable’ environmental problems, accused the Sustainable Development Commission of suffering from “chronic optimism bias”, and then essentially rigged the cost-benefit analysis to “prove” a barrage would be completely uneconomic.
The Severn Estuary Commission’s new report tactfully sets to one side what was, in retrospect, a very shoddy piece of work; it acknowledges that the ecological data currently available is still wholly inadequate, and that a new and comprehensive Environmental Impact Assessment needs to be urgently commissioned by DESNZ; it convincingly argues that a potential 9 GW of clean, totally predictable electricity from the Severn ( 7% of our current electricity use) could be developed within a very reasonable period of time (5 to 9 years for construction); and that by using a Regulated Asset Base method for financing, that construction would provide extraordinary value for money over the very long lifespan of any new tidal asset.
It also confronts the environmental challenge head on, advocating first for a ‘Commercial Demonstration Project’ (as the world’s first ‘tidal range lagoon’) to help fill some of the yawning data gaps and to assess what kind of ‘compensatory habitat’ might be required to offset any damage done to the Severn’s highly protected environment. Above all, it stresses the “risks of inaction” if these environmental challenges are still deemed to be insuperable. With the Welsh Government already fully on board, it urges the UK Government (which is, at best, “faintly favourable”, in the words of Andrew Garrad, the Commission’s Chair at the report’s launch, the Report’s launch) to commit to developing a new National Policy Statement for tidal energy.
These are very welcome recommendations for all those who will be very keen to respond to such a challenge – including those involved in the West Somerset Lagoon, which is probably the most highly developed of current proposals.
The response to the Commission’s report has been broadly positive. Peter Hain’s damning criticism (“very underwhelming, disappointing and confused”) seemed to be unnecessarily harsh – but then he’s always been a full-on advocate for a full-on barrage. As have I! It’s impossible to imagine any large-scale infrastructure investment in the UK capable of so convincingly demonstrating ‘Imperative Reasons of Over-Riding Public Interest’.
The real worry of all involved is that this critically important report will just ‘fall between the gaps,’ especially as the Western Gateway Partnership will soon cease to exist as part of Labour’s revamp of local government. That means there will be no one body charged with pushing forward on all fronts to see the Commission’s recommendations implemented.
I believe they’re right to be concerned on that score. Not least because DESNZ today remains completely in thrall to the nuclear lobby, which will see any major new infrastructure development on the Severn as a direct threat to its own cherished hopes for a new power station at Sizewell C – for all its confected enthusiasm for ‘all of the above.’ Behind the scenes, nuclear lobbyists will already be doing everything they can to kill off prospects for tidal energy on the Severn.
Part 2: Tidal Energy on the Severn vs. Nuclear Power
The biggest threat to the potential for tidal energy on the Severn is the Government’s obsessive support for nuclear power – including the prospect of a massive new power station at Sizewell C on the Suffolk coast (with a Final Investment Decision said to be “imminent”), as well as ‘in principle’ support for so-called ‘ Small Modular Reactors.’
DESNZ recently confirmed that an utterly astonishing £6.4 billion of UK taxpayers’ money has already been handed over to EDF to support Sizewell C since 2022 – and that’s BEFORE any Final Investment Decision! Notionally designated to enable ‘ preparatory groundworks,’ placing advance orders for equipment and so on, it’s almost impossible to imagine how EDF can have spent that amount of money. Inspired no doubt by the HS2 fiasco, EDF’s obvious game plan here has been to spaff enough public money all along the Suffolk coast so that Ministers will be too embarrassed to cancel the whole bloody thing.
(By the way, just to get this in perspective, £6.4 billion is roughly the same amount as the Government has committed to its entire Warm Homes retrofit scheme, and more than four times the total it claims will be saved (£1.4 billion) by cruelly axing Winter Fuel Payments for millions of pensioners and disabled people in 2024) As Sizewell C put it:
“With all the financial turmoil at present, it’s bewildering that the Government is essentially bypassing the Spending Review and pre-empting a Final Investment Decision, by committing so many billions to Sizewell C, despite its high cost and significant construction risk. Consumers need to know that Ministers still refuse to reveal what the project’s headline cost would be, yet every household will pay a nuclear tax on their bills through Sizewell C’s lengthy construction”.
The two reactors at Sizewell C are planned as a look-alike for Hinkley C on the Somerset coast. These are now at least six years late, with an estimated final cost of around £90 billion. EDF’s most recent estimate of construction cost for Hinkley C is £46 billion (in 2023 money), on top of which you have to include financing costs (the interest on the huge sums of capital required), which EDF has acknowledged could be roughly the same as the construction cost. Hardly surprising then that EDF has refused to publish any cost estimate for Sizewell C, let alone a target completion date, but it’s unlikely to cost anything less than Hinkley C – this is an industry that has demonstrated time after time that there is never any ‘learning’ carried over from one project to the next.
Beyond that, EDF is now seeking to further reduce its stake in Sizewell C. This was originally 20%. It’s now 14.6%. It wants to reduce that further to 10% – which is hardly a ringing endorsement for its own reactors! And we already know that these will be the last reactors of this kind that will ever be built: any new reactors EDF builds (in France or anywhere else) will be based on a new design.
It’s not possible, at the moment, to estimate how much a large tidal lagoon on the Severn might cost – it all depends on location, scale, construction cost, cost of capital etc. But I think we can safely assume that we’d be getting a shed load of clean, predictable green electrons from the Severn for anything approximating to £30 billion – let alone £90 billion!
When it comes to comparing nuclear and tidal, there are other critical issues to be taken into account. For instance, after 120 years of low-maintenance operation of any lagoon/barrage, there will be no waste to deal with over the next 1000 years (as will be the case with the waste generated by both Hinkley C and Sizewell C), and very low decommissioning costs, contrasting with the tens of billions required to decommission both Hinkley and Sizewell.
In any sane world, with evidence-based policymaking, Ministers would look at that choice (nuclear versus tidal), and make a rational decision, with taxpayers, energy security and cost-effective decarbonisation all properly taken into account.
But we don’t live in such a world. Decision-making on energy policy is neither dispassionate not even remotely transparent, partly because the Government’s pro-nuclear obsession is all wrapped up in the UK’s strategic need to “maintain the strongest possible nuclear industry here in the UK”. And that’s primarily to underpin our so-called ‘independent’ nuclear deterrent. In the final reckoning, decisions taken here are more about kilotons rather than kilowatts.
On top of which, we have to take account of the neanderthal pro-nuclear enthusiasts in the GMB. Which just happens to give the Labour Party huge sums of money every year.
Weirdly, the RSPB also deserves a shout-out here. It’s implacable hostility to harnessing the potential of the Severn Estuary’s incredible 14-metre tidal range has allowed the whole debate about environmental costs and benefits of any new investment to be profoundly mischaracterised, scaring off a whole generation of politicians in the process.
Which, over the years, has had the inevitable indirect consequence of green-lighting the insane nuclear projects at Hinkley Point and (possibly) Sizewell C.
Part 3: The RSPB Irretrievably Stuck in the Mud
Listening to Andrew Garrad on, Chair of the Severn Estuary Commission, launching its report 19th March, it was clear that the Commission had had early discussions with the RSPB, and had decided then and there that discretion would definitely be the better part of valour in addressing the critical environmental issues involved. Better to keep them sort-of on-board rather than guaranteeing a perpetuation of its implacable hostility by recommending a barrage. And they just about achieved that objective: RSPB’s main comment on launch was “tidal lagoons pose significant risks to nature.” Very measured!
I hope Andrew and his canny Commissioners don’t come to regret that judgement call. When any serious proposals for lagoons emerge, my bet is that the RSPB will be as negative and intransigent as it’s always been, stuck deep in the mud of its own mind-numbing, myopic prejudices.
Yes, the Severn Estuary is indeed a very special place, including a designated Ramsar Site, a Special Protected Area, a Special Area of Conservation, and several sites of Special Scientific Interest. The biodiversity of the Severn Estuary is impressive and important. The potential damage to all that (particularly to the estuary’s intertidal areas) has been judged historically to be so significant as to make it all but impossible to compensate for that damage, as required by Habitats Directive regulations and (latterly, here in the UK) by Biodiversity Net Gain requirements. Infeasibly huge sums of money have been suggested as the cost of creating compensatory new habitats.
But one can overdo all this. The Estuary is also an extraordinarily hostile environment, with tides racing in and out twice a day, scouring those ‘precious’ intertidal areas so brutally that not much invertebrate life that can survive, and that means there’s a lot less food for birds. It’s different higher up the Estuary (especially by the time one gets up to Slimbridge), but the further down one goes, the more impoverished those intertidal areas become . Heretical though this will sound to a lot of environmentalists, much of the Severn Estuary is far from being the kind of ‘biological wonderland’ that NGOs make it out to be.
What’s more, as the Commission points out on a couple of occasions, the Estuary is already increasingly affected by climate change with rising sea levels and water temperatures. Its salt marshes are already eroding badly. There’s absolutely no doubt that the environmental quality of the Estuary will be progressively degraded over the next two or three decades.
So imagine for a moment that the RSPB could extricate itself from the mud. A barrage (or even a couple of large lagoons) coming on stream by 2035 would still be generating “ predictable, low-carbon energy, independent of weather conditions” (as the Commission puts it) in 2050. By then, given what we now know about melting ice sheets, the projected rise in average sea levels will be between 1 metre and 1.5 metres – and it could be even higher in the Severn Estuary.
Astonishingly, however, the Commission’s report seems to have very little in it about the whole question of flood defences – despite the fact that Natural England and Natural Resources Wales are already required to bring forward proposals to compensate for habitat on the Estuary likely to be lost through rising sea levels.
Back in 2010, when DECC last looked at the issue of rising sea levels, (with ranges at that time measured in centimetres rather than metres!), it estimated that 100,000 homes and 100 key infrastructure assets would be at risk. It is now absolutely critical that a new Environmental Impact Assessment is commissioned by DESNZ to determine what the consequences might be of a 1 metre or a 1.5 metre sea level rise. The scale of the economic damage that would result from this is all but incalculable.
There’s a weird thing going on here: everything else about this decades-old debate about tidal energy keeps moving on: for instance, significant technology improvements, including modular methods of construction would reduce construction risk, and very efficient, low-head bi-directional turbines means that impacts on fish populations can be dramatically reduced; ideas about funding mechanisms (with a Regulated Asset Base approach) now offer real promise; the increasing importance of arguments about energy security post the invasion of Ukraine by Russia, and the absolute imperative of reducing our dependence on imported fossil fuels; our improved understanding of the speed with which the climate is now changing etc. It’s all change, all the time.
But the RSPB changes not one jot! When the Sustainable Development Commission published ‘Turning the Tide’ back in 2007, RSPB’s then CEO Barbara Young refused even to discuss our recommendations in any civilised way, threatening to be the first volunteer to blow up any barrage (and herself) should the Government have been insane enough to accept our proposals! Nearly 20 years on, the organisation is as firmly stuck in the intertidal mud today as it was back then.
With many other environmentalists taking their lead from the RSPB, I suspect it will still prove to be a real struggle to move things forward here, with the kind of urgency that is now required, even though the Severn Estuary Commission has focused its more modest proposals on tidal lagoons rather than on a barrage. Which means, in all probability, that we’ll end up with Sizewell C – a massively destructive new development just a few miles down the road from the RSPB’s wonderful reserve at Minsmere.
I don’t say any of this lightly. I’ve fought as hard as anyone for the protection of the natural world, for the recognition of what makes Nature so special (culturally, as well as ‘in and of itself’), and for setting aside as much of Nature as we can ‘beyond economic development’. But we’re talking here of a part of the natural world that is going to be devastated by human-induced climate change, unless we address that challenge now.
Which points to a very different leadership role for the RSPB. Given the Estuary’s inevitable degradation, it could take the lead on rethinking the whole ‘Biodiversity Net Gain’ story, acknowledging the potential benefits of a smaller but much richer intertidal area (with increased densities of invertebrates, waders and so on.) And beyond that, it could help shape what could undoubtedly be the most ambitious wetland creation scheme anywhere in Europe, building on the huge success of the RSPB’s Newport Wetlands Reserve created back in the 1990s to compensate for the loss of extensive mud flats caused by completion of the Cardiff Bay barrage.
The RSPB’s role as nay-sayer-in-chief has been hugely problematic over many decades. But we live now in extraordinary times – which the Seven Estuary Commission must hope will summon up extraordinary new leaders, even in the most improbable places.
Jonathon Porritt, April 2025
