Security and Energy from the Severn Estuary


Artist's Impression of the Integrated Severn Estuary Barrier

I have been bothered for some time about the Severn Estuary, which is wide open to storm surges, yet which at the same time has the potential to solve much of the UK's energy problems… Unfortunately, there have been many attempts to set up a barrage scheme to generate energy in the past, and these have rather dominated the issue, so that the notion of a Severn Barrier has been overlooked.†

So, let's get writing, and see if we can restore some sanity.


The Rt. Hon. Ed Davey, MP

Secretary of State for Energy and
Climate Change

The Rt. Hon. Patrick McLoughlin, MP

Secretary of State for Transport


Prospects for the Severn Estuary

Global warming and sea level rise are emerging as major environmental issues. Latest estimates indicate a mean sea level rise of 11mm over the last two decades. By the end of the century – if rising were to continue at the same rate – the mean sea level will have risen, globally, by about 1 metre. Not a lot, you might think, but it can amount to a considerable rise in the level of monthly spring tides, particularly in a natural funnel like the Severn Estuary.

Fast forward 100 years. Global warming has had the predicted effect. Sea levels have indeed risen by 1 meter, or more. Precious inter-tidal bird habitats from a century before have long been washed away, and mean temperatures across the globe have risen by several degrees. Increased thermal energy in the atmosphere has lead to fiercer storms, widespread flooding and deeper depressions—which in turn raise the sea level very considerably. One such depression is hovering over the Irish Sea, raising the local sea level much further, and whipping up a fierce southwesterly gale driving up the Severn Estuary, coinciding with a spring tide.

Result? A gigantic sea surge. Sea defences are overwhelmed at Barry, Penarth, Cardiff, Bristol City and Docks, Clevedon, Weston-super-Mare, Burnham-on-Sea, Watchet, Minehead and many others. The Somerset Levels, that low-lying area between the Mendips and the Quantocks, is inundated yet again with salt water and silt, further ruining this extensive area of farmland. Glastonbury Tor is an island again, as in medieval times…

It need not happen. Like the Thames before it, the Severn Estuary needs a Severn Estuary Barrier. A Barrier is designed to hold back high tide levels and storm surges, to protect up-river habitats, human and natural…as does the Thames Barrier.

Importantly, such a barrier would support major road and rail links between S. Wales and N. Devon, together with energy and fresh water supplies, the future need for which can now be foreseen.

Energy from the Severn Estuary – Pros and Cons

You will be aware of continuing interest in the use of the phenomenal tide in the Severn Estuary to generate energy; the tidal reach is reputedly the second highest in the world, offering sufficient potential green “Moon-power” to generate at least one fifth of the UK’s total energy needs, so comparing very favourably with offshore and onshore wind, and even nuclear energy.

Over the years there have several studies into the best way to tap into this potential energy bounty. The current proposition is for a so-called barrage, from Lavernock Point, Cardiff to Brean Down, Weston-super-Mare. The proposal has met with some opposition, notably from conservationists, concerned about the effects it might have on intertidal wading birds: objections may have also arisen owing to the projected costs of some £26billion (sic.) Unsurprisingly, perhaps, the current barrage proposal appears to have been “kicked into the long grass…”

A prior option, siting a barrage further out into the Severn Estuary, would potentially double the amount of energy to be generated under the current barrage proposal, according to a 1981 study under Professor Hermann Bondi, Chief Scientific Adviser to the then Department of Energy (1977-80).

Siting a Severn Estuary Barrier

To be effective, a Barrier has to connect between hills on both sides of the estuary. So, a good location for a Severn Estuary Barrier would be the hills between Minehead and Linton on the south side of the estuary, and between Porthcawl, Bridgend and Llantwit Major on the north side. A suitable site would employ hills on either side of the Estuary to prevent rising waters from going around the ends of the barrier, as it can do, potentially, for the Thames Barrier.

A Severn Estuary Barrier in the suggested location is going to be longer and higher than the currently proposed barrage, but then it has so much more potential.† In addition to being a Barrier to excessive spring and surge tides, it may:

®†††† Serve as a major generator of some one fifth (sic) †- or more - of the UK’s electricity needs

®†††† Carry an extension to the M4 from Bridgend across the Severn Estuary to North Devon, drastically reducing the drive time between, say, Swansea and Exmoor, N. Devon, Cornwall, etc.

®†††† Carry a much needed railway line.

®†††† Serve as an aqueduct, carrying fresh water from ‘wet’ Wales in the north, to the drier South West – part of the national freshwater pipeline infrastructure project which will be essential to address droughts brought on by climate change.

This Integrated Severn Estuary Barrier would be a major infrastructure project, offering employment over several decades to scientists, civil engineers, electrical engineers, hydraulic engineers and many, many more. But, how to afford it?

† † † † † † † † † † † † † † † † † † † † † † † † † † † † Financing and Economics

One solution is to build the barrier in phases, starting with submerged electrical energy generators. These tidal generators will generate sufficient electrical power to fund the rest of the barrier project, shown in the bulleted list above. †So, after the initial investment, the remainder of the project should be effectively self-funding… and that initial investment might be sought from energy companies. The remainder of this major infrastructure project could be spread out over as much, perhaps, as twenty-five years or more, making the per annum investment relatively modest, while providing much needed employment for many in an area of the country without much industry.

May I commend this Integrated Severn Estuary Barrier project to your joint attention? I believe it has the potential to satisfy a number of current, outstanding UK environmental and economic issues.

Derek Hitchins

Consultant Systems Architect

I got a reply, of sorts…

Dear Mr Hitchins,

Thank you for your e-mail of 7 December about Severn Barrage to Edward Davey. I have been asked to respond on his behalf and I apologise for the delay.

I would start by commending you on very interesting document and I thank you for this.

We are clear that the UK needs a mix of electricity generation capacity which is capable of delivering reliable and affordable low-carbon energy, and which can contribute to our energy security. We recognise that tidal barrages can have a role to play in this energy mix, provided the associated economic and environmental benefits and drawbacks can be reconciled.

†The outcome of a two-year, cross-Government Severn tidal power feasibility study was published on the DECC website in October 2010. Our conclusion from that study was that the Government does not see a strategic case for public investment in a Severn tidal power scheme at present, but that we would not rule out privately funded schemes: and this conclusion still stands. Before Government could take a view as to whether or not to support a barrage project, the proposal would need to provide strong, robust evidence that it has assessed the economic and environmental benefits and impacts.

†The Government is committed to harnessing the potential of marine energy to create a successful new industry in the UK. We have one of the most comprehensive support for marine energy in the world here in the UK - we provide R&D support for prototypes through the Technology Strategy Board, the Energy technology Institute and and Research Councils; we provide grant funding to demonstrate commercial-scale devices through DECC; and we have more than doubled support for wave and tidal stream under the Renewables Obligation.

Yours sincerely,

Daniel McHugh


You might think that this reply fairly comprehensively misses the point, notably about the need for a Severn Barrier (not simply a barrage) to address the major problems of extensive flooding. The Thames has a barrier, which is in very regular use - 300% more than when first built. The Thames Barrier came about because of the devastating storm surge in 1953 that inundated the east coast of England (see, which alerted politicians to the danger facing London via the Thames. It seems that Bristol and other centres of industry and population around the Severn Estuary will have to undergo a similar disaster before politicians wake up to the dangers.

You might think that—I couldn't possibly comment!

I have recently copied this letter, as above, to Owen Patterson—the Environment Secretary, who may have become concerned after the recent extreme weather conditions creating havoc in the west of England. Watch this space…

© D K Hitchins 2016