There’s a widely-held view that, to extract power from the Severn Estuary, you don’t have a choice: you have to build a large-scale barrage such as the Cardiff-Weston or the Shoots Barrage. If the environmental cost is catastrophic, it’s too bad we have to make sacrifices.

But we don’t. There are superior, lower impact alternatives that can do the same job, without the environmental damage.

A new generation of tidal turbine
A new generation of tidal turbines, being developed at Exeter University with funding from BERR (the Department of Business Enterprise and Regulatory Reform), has the potential to match the output of any barrage proposal - with very low environmental impact. And, crucially, without damming the river.

The moorable MRev Lift and Drag turbine is ideally suited to the Severn as it can be deployed in shallow depths and a wide range of flow speeds. Its compact size and flexibility means turbine arrays can be tailored precisely to a location. It also works on the flow and ebb (barrages only work on the ebb), producing a much smoother 24-hour power output cycle than barrages.

The turbine’s exceptional efficiency means that it could match the power output of any barrage proposal. And, unlike a barrage whose lifespan could be severely curtailed by silting, it could go on and on providing power, as a truly renewable energy source.

The problem with silty estuaries
Supporters of the Severn barrage often cite the small-scale success of La Rance in Brittany. Sure, it has worked well, but La Rance is not a silty estuary. Ask the Canadians about the Bay of Fundy and you get a different picture. Over there, silt has caused massive problems. No barrage proposal has satisfactorily addressed the massive problem of silting. In the case of the Severn, it would impede the efficiency of a barrage and reduce its useful working life. In short, barrage tidal power on a large-scale in a silty estuary is not a proven technology.

The need for transparency and scientific objectivity
As the debate moves on, one thing is absolutely essential. Tidal power solutions must be assessed on the grounds of technical efficiency, financial cost and environmental impact. It should be recognised that some of the engineering consultancies and sponsored “academics” involved in the consultation process have a vested interest in the construction of a multi-billion pound barrage. Can their advice be treated as wholly objective?

I must congratulate Jonathan Porritt for a beautiful and expensive presentation on BBC Wales “Week in / Week Out”. My fear is that one of the previous leaders in the environmental debate is being misled by the very commercial pressures that he wished to harness. Jonathan is presenting with great conviction and passion, the outmoded half-truths developers have been spouting for years to get a great construction project underway and feed the profits of their shareholders. This deception and manipulation deeply saddens me.

One has to ask, who is financing this slick presentation and how were they able to convince the BBC to present such a one sided and self-interested presentation on a national issue? This amounts simply to propaganda. I take my hat off to the consortium of construction companies who are straining at the leash to start pouring concrete into the river with their “get rich quick scheme”.

Clearly misleading

The barrage proposals were spoken of as “proven technology”. This is unfortunately simply untrue. There are no schemes like this any where in the world. Jonathan has fallen for one of the simple deceptions being pushed by industry that the tidal power plant in La Rance is comparable with plans for the Severn. Firstly the Rance River is tiny. The structure there is more like a bridge. And fundamentally, the water is crystal clear and not bit like the magnificent brown Severn. The important thing here and something the pro-barrage scientists continually gloss over is silt. Silt on a massive scale, silt that could render a barrage a dead lump of giant concrete in a stinking life-less river in a matter of decades. If anything has been proven about barrages, it is that they don’t work in silty estuaries. Scientists with years of experience on the Severn and similar estuaries worldwide are trying to warn us, but their voices are being brushed aside by the developers and Jonathan is blinkering himself and believing what he is told about the evidence.

In the program, much is made of Roger Falconer’s research in Cardiff University. I have no doubt that he is a well read and canny man. But his models have glaringly obvious flaws. The extensive plastic models are shown with steep sides and pumping clear water. This further promotes the myth that the Severn is like La Rance. So why is such a clever man, pushing these misleading models? What is his agenda? Could the fact that his research is sponsored by a Halcrow, a construction company be skewing his perspective? Is this the manipulative hand of industry influencing science for its own ends?

Old beliefs

Things have moved on since these old plans were first brought to the table. Jonathan, with his alarmist view of looming catastrophe, would do well to take his head out of the sand and look at the advances in technology. Devices now exist that would allow us to generate tidal power from the Severn forever, true renewable energy.

The pointless and emotive sacrifice of a fully functioning river system to the gods of climate change is a misguided indulgent “green” luxury. Jonathan’s “mega green” project is simply not what he is claiming. I fear his well-earned reputation as the “high priest” of environmentalism is being tarnished by a diet of manipulative misinformation.

The Sustainable Development Commission states that, because of siltation, a Severn barrage could lose half its capacity within just 10 years. The Government defines renewable energy as being inexhaustible. Can a barrage across the Severn be described as producing “renewable” energy if it “uses up” the resource, which is the funnel shaped estuary?

Government studies show that silty estuaries are not suitable for tidal range storage schemes like barrages and lagoons. In Canada, where similar schemes have been tried, whole estuaries have been become blocked with vast expanses of mud. How long could the Severn estuary produce power in this state?

If the Severn flowed with crystal clear water like La Rance in France, then a barrage might work. But La Rance’s geology is totally different with tidal power produced in an estuary with steep granite sides. Even so, silting problems here have meant this pilot scheme has not been rolled out.

Learning from a costly Canadian mistake

Prof Simon Haslett from Newport University has studied the Severn for over ten years, he said:

“The Canadians have been experimenting with tidal power generation in the Bay of Fundy for many years, building a barrage across one of its tributaries as long ago as 1984.

The consequences have convinced them that building a barrage is inefficient, has many undesirable environmental impacts and is unsightly.

For the Canadians the idea of a barrage is now history and doesn’t even get raised as an option during tidal power debates.”

It’s mud and it sticks

Dr Graham Daborn, a world-leading expert on estuaries, points out that estuarine silt can’t be modelled in the same way as sand - a non-sticky grain. As a living thing containing mini molluscs, bacteria and worms, silt deposits are stickier than sand and do not simply wash away. In fact, silt accumulations could be around 80 times stronger than traditional modelling predicts. He states that, “such accumulations would quickly fill up an estuary”.

The harnessing of truly renewable energy is possible in the Severn using tidal stream turbines. These are devices placed in the tidal current a little like underwater windmills. Canada is already embracing this leading edge technology in the Bay of Fundy - with turbines produced right here in the UK! The latest tidal stream devices are perfect for the shallow Severn.

To continue down the blinkered path of barrages and tidal storage solutions is fruitless. Not only is it exorbitantly expensive for the UK taxpayer, it is unlikely to work for long, it will destroy an irreplaceable resource and leave an indelible scar on our landscape. We need to help our Government embrace more effective, lower impact and truly renewable technologies.

Stuart Ballard
Save Our Severn

New silt modeling methods by Dr Graham Daborn, Acadia University Centre for Estuarine research, Nova Scotia, helps us understand just how fast mud is deposited. A Severn barrage could lead to the beaches of Wales and the South West being plastered with a living slime of mud.

Traditional models like those now being used on the Severn, treat silt in the same way as sand, a non-sticky grain. Silt however is a living thing. It is full of tiny life. These mini molluscs, bacteria and worms secrete mucus that hold the sediments together. Dr Daborn’s studies have shown that this produces deposits 80 times stronger than traditional models expect and which do not wash away. He states that, ’such accumulations would quickly fill up an estuary’.

The outdated models are being used right now to give misleading information to the company doing the feasibility study. Using incorrect modeling has lead to disasters in the past. Dr Daborn gives three examples in Canada where this has lead to barrages being constructed resulting in massive sediment deposits choking the river, leading to flooding and blocking harbours and destroying fisheries. Mud was deposited at a rate of 15cms per month. This mud now extends 11km down stream of the barrage and is still growing. On the Severn this would plaster the beaches of the SW and South Wales with a living slime of mud. The beaches would be gone.

Silt arrives in the Severn from both direction leading to choking mud downstream of a barrage and silting of the ‘head pond’ above it. Resulting in loss to the economies of coastal resorts and harbours and increased flooding above and below the barrage and loss of generating capacity.

It is time we admit the fact that the Severn Estuary is not suitable for a barrage. Research by Dr. Daborn and other experts from around the world shows it simply just would not work.

Full extract of Dr. Daborn’s barrage study can be seen here:

http://saveoursevern.org/dr-graham-daborns-report-on-silting/

Gloucestershire County Council are being lead headlong into a mire by misinformation about the proposed Severn barrage. Barry Dare, Council leader, is being misinformed and in turn is misleading people. He seems to be under the impression that a barrage would produce cheap electricity. Any electricity produced from a barrage would be very expensive. The study prepared by the National Trust and nine others NGOs released last week, states any electricity would be very expensive and would equate to bigger bills for all. Gloucester County Council should be calling on the Government to spend money earmarked for the Severn on a ‘Green Energy Zone’ - micro generation and insulation for all, encourage ‘Green Technology’ to the area, boost the regions economy and importantly provide proper flood management for Glos and Tewks. Studies have shown that a barrage would increase the chances of flooding in Glos and Tewks by reducing the rivers capacity to transport water away. It would also increase flooding down stream. Who would pay for dealing with this? A barrage is not suitable for the silty Severn and not the way to reach 15% renewables by 2020 there are cheaper better ways. Experts believe even the feasibility study is a waste of money especially as it being undertaken by one of companies proposing a barrage.

A group set up in support of the barrage proposal are making a host of misleading and exaggerated claims. They repeat the spurious claims from developers that a barrage is designed to provide flood defence and the amazing idea that the turbines would be so benign that not only can salmon pass through unharmed but also that a man can too!

Research has shown that up to 15 % of small salmon “smoults” returning to the sea are killed by these sort of turbines. What chance would adult breeding salmon have as they are swept up and down the estuary by the tides, having to face the grinding turbines more than once.

If their claims are true, then send me through the turbines! Let’s see if the whirring blades of high pressure turbines will leave me alive let alone unscathed. I’ll see you on the other side.

Barrages are not “green energy” and the claims for them continue to be exaggerated whilst ignoring scientific research from around the world.

Those backing the ill-conceived Severn barrage are in for a shock when they find they are not the leaders in tidal power technology. The Severn Tidal Power Group, the group of developers and engineers pushing for a barrage are trumpeting how they are pioneering the development of tidal power whilst dragging the same old antiquated schemes to the table. Mean while, Canada is forging ahead. Experience has shown the Canadian Governmant that tidal barrages just don’t work in silt laden estuaries and the environmental destruction and increased flooding is just too high a price to pay for so called ‘green energy’. STPG have had a march stolen on them by the Bristol based company, Marine Current Turbines. They have been steadily developing and proving cutting edge technology which has now been adopted by the Canadians for the Bay of Fundy. We should learn from this and demand that our estuary, river and adjoining country side be spared from the greed of the developers, spared from environmental disaster and our countryside and houses be spared from increased flooding. Tidal stream turbines are the solution to the question of tidal power from the Severn a barrage is not.

The WWF point out that:

‘wetlands are economically valuable biomes that provide goods and services upon which many communities and economies depend. Recognizing the economic importance of wetlands in addition to their biodiversity, scientific value, climate regulation, potential tourism, socio-cultural and other important wetland values is yet another good reason to reverse global wetland loss…

Dams disconnect rivers from their floodplains and wetlands. The damage to freshwater ecosystems can be devastating. They impact on the migratory patterns of fish, and flood riparian habitats, such as waterfalls, rapids, riverbanks and wetlands.

By slowing the movement of water, dams prevent the natural downstream movement of sediment to deltas, estuaries, flooded forests, wetlands, and inland seas, affecting species composition and productivity.

Dam operations also influence water quality. Water and sediment retention affect water quality and the waste processing capacity of rivers (the ability to break down organic pollutants). This could lead to production of toxic hydrogen sulphide gas that further degrades water quality.’

With thanks to Save the Ribble

There is wonder in technology and human ingenuity, but the most wonderful technology is one that leaves nature intact and thriving, while deriving benefits for human society. Invisible, replaceable, upgradeable, removable, sustainable and modular. Elegant not brutal, clever but not macho, evolving, not monolithic.

Morgan Parry
Head of WWF Cymru

Prof Simon Haslett, Head of Geography at Bath Spa University has been talking to the Gloucester Citizen and has this to say:

Canadian scientists are urging the British Government not to go ahead with the Severn Barrage. They have warned it could cause major environmental damage and waste millions of pounds of taxpayers’ money.

Concerns about the planned Severn Barrage came to light at a major environmental summit in Canada.

Bath Spa University scientist Prof Simon Haslett, who spoke at the conference, says Canadian scientists are alarmed about the scheme from their own experience of harnessing tidal power.

The head of geography in Bath Spa’s School of Science and the Environment is warning that Britain should not make the same mistakes.

Prof Haslett gave a briefing on the Government’s proposal to build a barrage across the Severn Estuary at the annual conference of the Atlantic Geoscience Society in Halifax, Nova Scotia.

His presentation was part of a special session on Canada’s own experiment with tidal power in the Bay of Fundy.

This has the highest tidal range in the world, even higher than the Severn Estuary.

But Canadian experts at the conference told him the Bay of Fundy scheme had caused serious environmental damage and they were shocked that a Severn Barrage was even being considered.

Prof Haslett said: “The Canadians have been experimenting with tidal power generation in the Bay of Fundy for many years, building a barrage across one of its tributaries as long ago as 1984.

“The consequences have convinced them that building a barrage is inefficient, has many undesirable environmental impacts and is unsightly.

“The UK needs to learn from their experience and not make the same mistakes.

“For the Canadians the idea of a barrage is now history and doesn’t even get raised as an option during tidal power debates.

“It’s so old that they are amazed the UK is even considering it.

“The Canadians now only use turbines that are placed in the tidal stream, so that electricity is generated both on the falling and rising tide.

“Some turbines are submerged on the seabed, so you can’t even see them - a bit like undersea wind farms.”

Prof Haslett has researched and written extensively on the Severn Estuary over the past 10 years.

“If the Canadians are right, we shouldn’t even waste any time and millions of pounds of taxpayers’ money considering a barrage,” he said.