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50 responses to “Dam Fuel Poverty”

    • Debra

      Around 15 years ago, I worked as an energy advisor in an area of Birmingham with massive levels of fuel poverty. It’s depressing to realise that after so much time not much has changed.

      I do like your idea of providing free renewable energy, but I think it would need to be coupled with home energy efficiency improvements. People in fuel poverty tend to live in some of the hardest to heat homes, so they simply have higher fuel bills. Making energy efficiency improvements would make it easier to lift them out of fuel poverty and mean that as a nation we’d be wasting less fuel. And that would benefit all of us. thing.

    • Damon Hart-Davis

      Rather than the vanilla main Barrage suggestion, I like some of the twin-tidal-pool alternatives that I have seen mentioned which are probably less environmentally intrusive (eg no blockage of transport and on fish-fingers!) and can potentially generate power on-demand 24-hours per day, albeit at the cost of lower extractable energy in this case.

      Rgds

      Damon

    • Xena

      Not knowing a great deal about what the severn barrage actually is, it would be really useful to have info on what it would involve to build it. Is it a damn, a whole load of turbines, mixture of both? I’m really interested to read about it and understand more…

    • Justin Noe

      Should the plan get the go ahead and the impact to the ecology of the area be minimal why would ecotricity not be interested in building the wind turbines? Planning permision would be easy and it would save the project money.
      Perhaps the worry is over any negative publicity.

    • paul

      Thanks for pointing that out Xena! We have now added a few links on the bottom of Dale’s post to more information about the Severn Barrage. I hope you find this useful.

    • Chris

      Unfortunately I think we’ll have to realise that local ecologies will be ruined anyway if we don’t do something about the global issue. Add to that, the sustainability issue is really as big a problem as the environmental issue.

      This article has some interesting facts and figures. Apparently by 2010 the UK will import 50% of all our gas and by 2020 we will import a whopping 80%! Ouch.

      http://www.parliament.uk/documents/upload/POSTpn230.pdf

    • Adi

      Interesting angle – Yes totally support the Barriage – could last longer than 100 years too.
      I looked into this a few years back and found that a large Construction firm had done about 73 surveys to aid decision making about 15 years ago. The chap I spoke to said that a large new factor is now present to assist the other issues surrounding it: I.e. flood alleviation for Gloucester! This maybe the required extra reasoning to help it go ahead. The elver migration (and other migrations) is an important point but a side channel could achieve that. The Mud flats is not really an issue for the birds as many already using Norfolk Broads instead as climate already changing and arguably there may be more (albeit new) flats created by the construction.

      Tidal lagoons have been put forward as an alternative by the Green Party locally (which really annoyed me as its spineless like usual).
      because they produce an absolute fraction of what the barriage would.

      Good Call Dale

      Adi

      now

    • Paul Mobbs

      Yeah, but electricity generation in the UK grew by 5% between 2000 and 2007; ergo you could build the barrage and within a decade we’d be back to square 1. Now, I’m all for stopping the economy growing because it would really benefit the environment, but I challenge you to get anyone who supports the barrage to give the same commitment (I have; so some reason they’re not keen to sign up to the idea!).

      If we look at the future challenges, especially peak oil, climate change and population growing faster than food production, we don’t need a policy to produce more energy — we need a policy to use MUCH less.

      We know how to make energy — in that wonderful Pythonesque term, “it’s a doddle!”. What we don’t know how to do is reduce out energy use in order to adapt to a depleting resource base and escalating carbon emissions. And from my own experience, those in the mainstream won’t even consider this option because it doesn’t fit with the current consensual delusion of the growth economy.

      If you really want to make a difference stop promoting the “more” economy and start advocating the only option that works in engineering and physical terms — having less.

    • Adi

      Hi Paul,

      Its not about “more” its about “replacing” (and reducing a bit – as you suggest). Lets be frank: no amount of conservation measures is going to solve the problem of restraining global warming to within a 2C rise – given the time we have and the momentum of energy consuming demand. Some reduction (conserving) tied in with replacing fossil fuel generation and an optimistic outcome with Obama at the Copenhagen 2009 international commitment “crunchtime” meeting, just might do it.
      Copenhagen (and the resulting carbon reduction commitments if it works) could be the last chance for up to 60% of Nature’s species. At least Poznan meeting wasn’t a complete disaster, so the barriage ought to be seen in that context I believe.
      Adi

    • Brian

      I have to say I agree with Adi. Afterall how can a rapidly shrinking economy work in reality? Sack half the population?! Add to that, although I can see the flaws of capitalism & unregulated profiteering, it’s not all due to greed & waste. Some economic growth is down to population growth and advancements. Some advancements none of us would want to give up! Plus, consuming less in itself may drive the economy through developments like energy saving technologies. Consuming less is also very difficult to regulate as everyone has very different ideas about what is necessary. I’m just saying it sounds a little idealist if sound in theory.

    • Neil Law

      I must admit that I’m staggered at the naivety in this whole proposal. There is no credible evidence that any tidal range-based proposal will even work in the Severn Estuary. In fact, there has only been one tidal range project which could feasibly be categorized as a success,and that is La Rance. That plant exists in a very low silt environment, which the Severn Estuary certainly is not. I urge you to talk to the Canadians, who have been trying for decades with tidal range, and seem to think we’re insane to be contemplating such a thing in such an environment. Have a look at some of their experiences. Have a look at Moncton causeway, have a look at Windsor, and give closer scrutiny than was offered by Black and Veatch in “Turning the Tide” to Annapolis Royal. A barrage will not work for more than something like 5 to 15 years, and people need to start getting their facts straight, and looking at where the misinformation is coming from. In my opinion, it seems to originate from people with a vested interest in large construction projects.

      The potential for disaster is enormous, and it is therefore imperative that we look at tapping this undoubtedly large supply of power in a way which genuinely IS renewable. Unfortunately that rules out all currently available forms of tidal range generation.

      Tidal stream technology is advancing rapidly, and may provide some answers. Already there are turbines available which can now be sited in relatively shallow waters, and that was not the case even 2 years ago.

      I urge you to look again at this. You are making a desparate mistake, which I sincerely believe you will come to regret. Please look at what has happened in other highly silt-laden estuaries where barrages have been built. Try speaking to the likes of Dr Graham Daborn, who has studied these events and will be able to give you chapter-and-verse reasons why tidal range is not an option for this estuary.

      Thanks. Sorry about the rant, but I am as sincere about this as I believe you to be, or I wouldn’t have bothered posting at all.

    • Martin

      Without getting into the rights or wrongs of the barrage – I do have a probelm with the way fuel poverty is defined. Say I earn £1000 and spend £90 a week on fuel, according to the government definition I am not in fuel poverty. So if I leave some appliances on, don’t switch lights off at night etc my fuel bill goes up to £110 a month then I am now in fuel poverty – and under this scheme entitled to cheap or free electricity – there must be a better way of defining this as you can see what everyone might do….

    • Sophie

      Not so sure about the severn barrage – although i do believe that feasibility studies have been carried out by at least one of the big 6. Would it not be more beneficial to explore this method by looking at current installations within the UK? For example, the Thames Barrier, which is nearing the end of its engineering life span, I am sure a proposal of installing some kind of turbine in the individual gates would be better. Also the barrier is currently being lowered increasingly and this will only happen more frequently due to the effects of climate change.

    • Neil Law

      Sophie,

      I don’t doubt that there are places where tidal range generation CAN work, because that is precisely what La Rance suggests. However, Moncton, Windsor, and several other plant clearly demonstrate that it is certainly not always a renewable resource,and when used inappropriately it represents just another way of stuffing up our world,as well as representing a potentially great danger to the lives of people as well as the ecosystem.

      Potentially, turbines could be placed in existing structures such as the Thames Barrier, if it doesn’t cause a problem with siltation and such.

      But we have one of the most extreme tide environments in the world. There must be a way of tapping into it. Is there no way of placing a tidal stream turbine in a position such as Corryvreckan? The amount of energy there must be off the scale. And what about other situations with extreme tidal races, such as locations within the Menai Straits?

    • Sam

      @ Neil,

      the worry about impact, in terms of silt, from a turbine point of view is probably unneccassary since the foundation footprint is usually no more than 20m radius.

      it is usually the more extreme and intense energy sources that are near impossible to harness, better to have a steady and controllable tide.

    • Neil Law

      Maybe I’m not understanding this point, Sam. I am a lay person in terms of the engineering, but I was concerned about the barrage because it seems to make little sense, so I just followed a line of inquiry via google using keywords like “Macrotidal estuary” ” Tidal Power” “Tidal Range” and so on. That led me into an e-mail conversation with people who have done work studying what went wrong in some of the Bay of Fundy projects, and I have now been looking into this specific issue for something like 18 months. I still see no credible evidence that the Severn Estuary will end up as anything other than another Moncton. The tidal range will reduce to some extent, and taking energy from the water will cause silt to drop out of suspension. The fine particles will be acted upon by things like phytoplankton and benthic diatoms, as they were in Moncton, and we will end up with a headpond AND an outer estuary rapidly filling with mud, because the tide will no longer have sufficient energy to resuspend it before it consolidates.

      Please tell me how this is inaccurate? I would (sincerely) love to know.

      And what is so bad about tidal stream generation that we can’t use that instead?

      Neil

    • Sam

      i understand that the barrage has a lot of questions hanging over it in terms of ecology and feasibility. Only in terms of energy, and harnessing it effeciently, is the severn estuary probably a good location, in comparison to the locations you mention.
      but that’s just an opinion based on other forms of power, i’m not well versed with tidal.

      You mentioned turbines for the Thames barrier and possible concerns, i believe (purely from a turbine affecting ecology point of view) there wont be a massive impact.

      theres no doubt that the barrage will change things ecologically, from the sound of what you’re saying theres a good chance it will be v. bad, but the blog is trying to avoid that side of the argument. (me too since i havent go a lot of knowledge in that area)

    • Neil Law

      Thanks for the reply Sam.

      Obviously, this is something that I’m passionate about, and the press commentary in the last 24 hours is how I came by this website. I have absolutely no wish just to end up wittering on in some sort of nimbyist tones, because having had a look around the website, I think I probably share a lot of values regarding renewable resources with other people hereabouts. But I get very alarmed when people I would normally regard as natural allies go into print supporting something I regard as almost entirely dangerous not only to ecosystems, but to humans as well.

      I’m Joe-nobody, and I found out quite a bit about tidal energy, and the history of it just by number crunching and being willing to get in people’s faces enough to ask questions of busy academics, elver fishermen, historians, and anyone else who would reply. What surprises me is the difference between what I found out, and what research carried out by large corporations who have a lot invested in this managed to find out.

      And yes, by the way, I am cynical about their approach. I would far rather see something that would work being built.

    • Adi

      Hi Neil,

      By your own admission, you say you don’t know the engineering side. Well neither do I much this but here are my thoughts:

      Assuming the design was made to harness the tidal power on the down flow (so flow through turbines is regulated over the whole period of downstream flow – Eg over 12 hours between tides). The upstream flow therefore must be allowed by open gates to allow the huge body of water to get upstream – so that later is can be harnessed slowly (in a regulated fashion) on its downstream journey. It occurs to me that therefore with good design the upstream surge of a barriage can still flush/suspend deposition of silt to some extent on its way upstream. Similarly, once the barriage was built, a huge reservoir of water would be available to periodically flush silt downstream – with flushing power possibly greater than what would naturally flow due to a greater head (height) of water pushing it down. Even if these two options didn’t work, a barriage might still be the right thing: i.e. harness the inflow current as the tidal waters go downstrean (like normal) but also have the combined benefit of a flood alleviation sysytem – flooding has caused massive problems in the gloucestershire area and is going to get worse as sea levels rise!
      The disadvantage of the last option (inflow downstream) is you couldn’t regulate it to provide a steady amount of electricity in that scenario.

      I just don’t believe that there is not an engineering solution to the silting. I do share your concern about the management of the regulation of the flow rates though – as mismanagement of flow rates to optimise electricity production on the short term could cause build of silt. So the criteria of open/shutting gates after a good design is built is what would concern me. This is a management issue NOT an issue about whether the barriage could deliver or not.

      I’m all for the barriage still but would want to see water handling regulations.

      Regards

      Adi

    • Neil Law

      Adi, thanks for the response. It’s much appreciated.

      As I said, I had gone out of my way to get in people’s faces to get hold of the information I needed. My primary stimulus for this was the flooding of July last year..more of that later.

      The most detailed information I received was from Dr Daborn, of the Acadia Centre for Estuarine Research. he very kindly took the time to explain to me how silting had become such a problem for other barrages, and why he is convinced it will kill an Severn barrage. There are a couple of factors to take account of. Firstly, the tide is not an even, measured in and out.. you can’t represent it as a smooth sine wave on a graph, because the inflow is much faster and more powerful than the outflow…remember the Severn has a tidal bore,which is a large part of the tide arriving all at once.. The huge silt load it carries is effectively punched inland with great force, and then the tide recedes more slowly. In the upper areas of the estuary, say from Sharpness to Epney, this has reached a natural equilibrium, where the force of the mean river flow at low tide is sufficient to keep the existing channels clear. But when silt is rammed upstream, then falls out of suspension at slack tide, it takes at least the same force to re-suspend it as it took to carry it there in the first place.

      That energy simply isn’t there on the receding tide,especially one which is slowed by passing through turbines. Then the mucus secretions of marine microorganisms get to work on the fine particles carried both downstream from the soils (mostly of Worcs and Gloucs in this case) and from soils freed up by coastal erosion outside the barrage..and this position is critical. When fine particles and these diatoms and phytoplankton come together in this way, they make the liquid mud which kills barrages. When that dries, it is 80 times more resistant to erosion than the sands and gravels that the engineering models account for in their mapping of siltation effects. For the engineers, this is simply off the radar!

      Secondly Dr Daborn pointed out that if you slow the current in either direction by 50%, and barrages do at least that much, often more, then you reduce the capacity for carrying silt by an order of magnitude. In this case we are talking about an 8-fold reduction. This also represents an 8-fold reduction in its ability to carry silt, so the silt drops out, and coagulates. And the stuff is like velcro. Once it’s there, other silt will stick to it. A cycle of siltation kicks off which is very difficult to control.

      Dredging? Not an answer, apparently.. after all, those engineers who built Windsor and Moncton didn’t just sit back watching their project go down the tubes. You and I both thought of dredging as an option, so did they. Dredging is very costly, and the need for it will never end. It is also relevant to suggest that it currently uses quite a bit by way of fuel, and the areas most in need of dredging are those which a vessel will find most difficult to access… the shallows, where the current is slackest. If you gouge out an area, you may well create an area of accelerated water flow, with higher energy. Energy can’t be created or destroyed.. you need to think about where might now have less energy.. and more than that, you need to be aware of scouring.. the opposite of siltation. When the speed increases in a localised area the water will scour/erode new sources. Unfortunately, these are fairly unlikely to be the old silt deposits, because once they have been around for a while, they are incredibly persistent. It will more likely be areas of dry land/coastline. So every cut of the dredger will need careful planning.

      I take it you haven’t done any google search for Moncton? Look at a few images. The siltation occured OUTSIDE the barrage. As I said earlier, where the material comes from is important. We have to worry about both river-borne silts, and soils from Somerset and North Devon that will be pushed up against the outside of the barrage and there it will remain.

      I think I’ve waffled enough. There is a lot of misinformation about flooding as well. It does not prevent events such as last year’s floods to have a barrage in place, although it WOULD reduce the impact of the cataclysmic events such as the great flood of 1607. There are only very particular times at which it would help reduce river-borne flood events. At many other times it would make things worse.

      Neil

    • Linda Moore

      Thank you for the opportunity to reply to this blog; much appreciated.

      I agree with Neil: you’re making a mistake. Huge engineering projects are tempting because they appear to offer an economy of scale at a time when a very rapid level of change is needed; however, I can’t think of a single example where the costs predicted have been realistic in even the short term… and I have seen and commented on hundreds of schemes, both energy-related and otherwise, as an ecologist, over the last 20 years. Messing around with the most powerful river in the country, with huge tidal ranges, huge and variable silt loading, fishing and navigation issues, and a vast area of internationally-protected ecosystem, is not justifiable. Especially given the uncertainty over the success of such a scheme.

      I am also very worried about the lack of concern for the ecology here. To state baldly that “the only losers are the Big Six” is quite extraordinary, because the environmental damage would be colossal, even without considering the enormous amount of aggregates that would be required for the project. Don’t ever forget that the damage caused on the ground is a fraction of the impact of big engineering projects. All that stuff has to come from somewhere: gravel and sand extraction, Portland cement, imported structural materials… lots of carbon involved there, and lots of towns and villages with trucks going through day after day, week after week. Is Dale suggesting that every reputable conservation body is either mistaken or not worth considering? Given the fuss that we would likely be making if a foreign government proposed something so damaging to a large area of protected ecosystem, I find this amazing.

      Please don’t fall for the promise of ecological mitigation! Even when it works as predicted (rarely) and when money remains to carry it out (almost never – it’s always the first thing to be squeezed out when costs rise) it can’t replace an established habitat on such a scale.

      Saying that the system would be damaged by climate change in any case is an argument for *not* doing anything which would stress the environment to this degree… estuarine systems are very good at adapting to everything except confinement. They need to be left unimpeded. Note also that flooding from strictly tidal sources (like the “tsunami” of 1606) is not normally such a problem for the county as “filling up”, i.e. caused by rainfall. Flash flooding is *not* improved by any form of barrage; it doesn’t come from offshore and might even be made worse by impeding the flow out of the estuary.

      The above comments seem fairly obvious to me, and I don’t think I’m alone in that respect. We mustn’t let our strong desire for a solution to the problem of unsustainable electricity production corner us into supporting yet another huge, unpredictable scheme with many hidden costs – and ecological damage which would be prohibitively expensive, or impossible, to remedy.

    • Neil Law

      The project at Strangford Lough ..now that is something which seems much more likely to do the job.Barrage design doesn’t seem to have advanced significantly in decades, but TST’s are leaping ahead almost week by week..I like…I support.

    • John Connett

      I can thoroughly recommend the following book:

      David J.C. MacKay. “Sustainable Energy – without the hot air”. UIT Cambridge, 2008. ISBN 978-0-9544529-3-3. Available free online from http://www.withouthotair.com.

      I have just read Chapter 14, “Tide”, which has a good coverage of tidal power including barrages. This includes two Severn barrage proposals, one at Weston-super-Mare and the other further down the estuary.

      All of the reasoning is backed by calculation. Not a particularly easy read but well worth the effort.

      Definitely a positive step in “cutting UK emissions of twaddle – twaddle about sustainable energy”.

    • Neil Law

      I’ll get hold of it and have a read. If I could manage research report 3 in “turning the tide”, I can probably manage most things.
      🙂

    • Neil Law

      I’ve downloaded it, and I’ve read the tidal power section. I’m sorry, readable as it is, it forms no basis for understanding the practical appliance of the thinking. I technology cannot said to be “proven”(barrages) when there is one entirely successful barrage ever built, and several disasters.

      The basics about tidal circulation around the Atlantic Basin is well set out , though,and I wish I had learned by reading that section , rather than the soporific stuff i was presented with.

      In the case of tidal range, it is very important to recognise the importance of apparently subtle variations in long term tide cycles. There are several of these, each with their own characteristics, such as the Nodal and Saros cycles, both of which are in the region of 18 years long. Overall they give rise to variations in max spring tide height for a given year of only 3 or 4%, but there have been some very relevant findings about relative fish stocks varying in number along with those cycles in the Minas basin, and a relatively small variation in tide height can give a disproportionately large variation in available energy… for an example of this, look up the max tide heights at Avonmouth over a 25 year period on the website of Proudman’s Oceanographic research.. look at the heights for this year, and compare not only with the height for 2015, but also for how many really big tides there will be.

      Extra height of tide equals extra water captured in a tidal range facility. Given the likely shape of the bed ..a flattened “V” shape,,the profile of the Severn estuary in all dimensions, a higher tide of ,lets say, only a foot more water means a massive increase in potential energy stored, because the area in which it is stored gets wider, the higher the tide is. But equally, tides such as we have had this year, at the bottom of a cycle, will produce a great deal less energy for the same reason.

      So much as it would be good to simplify tidal energy, when you do so, you sacrifice truth to simplicty, and that isn’t helpful.

      Then there is the question of siltation… why is it not mentioned? It isn’t a constant, and it has killed several barrage schemes.Again, over simplifying has removed truth.

      Tidal stream. I didn’t notice any mention of the turbine off Lynmouth. Did I just miss it?

      Overall, I like the style, but the content is poor, and that saddens me. This is the kind of misinformation that has got us to the place where people think it’s a great idea to commit an act of monumental vandalism in the name of protecting the planet in some way.

    • Adi

      Trouble is: if we do nothing we could lose up to 60% of all species anyway! So to lose a few locally only is a small price to pay. The time for dithering about perfect solutions is gone.

      Neil, most of your concerns don’t worry me except the build up of silt OUTSIDE – the inside build up is managable in my opinion. How about asking the engineering company that originally proposed the barrier in the 80’s about the build up of silt fronm the outside? They did numerous studies. (I’ll try and dig out the contact I spoke to who was still there 3 years ago). Also what is the power potential of inflow turbine systems (or other alternative tidal harnessing like lagoons)? If it isn’t a great deal less- fine, but I suspect it is massively less.

      As an ecologlost I find that we are our own worst enemy particularly on renewables. In the name of environment people complain about wind turbines.. in Iceland a huge dam project I visited a few years back – which could have saved vast amounts of carbon going into the air was fought by environmentalists. Biofuel, the most flexible and storable of all renewables has been thrown out by many environmentalists because they fail to be able to differentiate between that which is sustainably sourced and that which isn’t.
      And so on..

      Neil another point: If the gulf stream stops as soon as it is feared it could, you wont have any of the long term tide cycles to worry about! Even if the barriage is built the gulf stream is likely to stop anyhow – potentially rendering those concerns void.

      Dale, could someone find out why the interested engineering companies seem to think the silt build up Outside isn’t a problem?

      Tidal and Biomass and Wind and Solar and Wave must all play parts in the package of solutions for the future. Tidal has got to be easier than an equivalent amount of capacity from wave power (which could power 12.5% of current UK demand whilst tidal could power 15%).

      Adi

    • Neil Law

      Adi, there’s no dithering here. Energy and cash spent on building the worlds biggest white elephant is a bad idea in any climate, at any time.

      I’m by no means suggesting we do nothing, or build nothing. Tidal stream turbines can now be used in the Severn estuary, so why did the govt rule that option out?

      Maybe because the engineering interests on the SDC have no investment in it..call me cynical, but how closely have you been monitoring their activities? There are some things I have been made aware of which I wouldn’t post anywhere, because I can’t afford lawyers. But here’s something to ponder: The Shoots barrage was originally backed by Parsons-Brinckerhoff. The technical specs for report no 3 within ” Turning the Tide” was carried out by Black and Veatch, a member of the Parsons-Brinckerhoff group. Parsons-Brinckerhoff were then awarded the contract to run the feasibility study for the govt..

      Come on guys. You don’t have to be a crazy conspiracy theorist to think it’s worthwhile asking a few difficult questions here. The process is meant to be transparent, right? All of the “technical experts” on barrages who contributed to the SDC document that I’m aware of.. and I’m not claiming to have checked them ALL out, are people who seem to have a (possible..alleged) vested interest in building a barrage.

      So start building your knowledge again, if that’s where it comes from. Why are the canadians, the most experienced people in the world with tidal range…why are they no longer considering most of these sorts of scheme? Look for a few people with no axe to grind. If we screw this up, we could be killing the estuary, and that is only the beginning of it. We are messing with tidal flows. Where are the modelswhich show how they will be altered? Where, given that a large proportion of the tide will “bounce ” off the structure, where will that water go? Where will have an enhanced tide? Are those areas prepared for seaborne flood events? Are they prepared for heavy duty coastal erosion?

      Adi, did you mean the Thames barrier? I’m not sure that’s relevant. The problem with the Severn does not exist on all rivers. It has an extreme silt load, and sources of new silt material available in abundance on both sides of any potential structure. It is dissimilar to the Thames in that respect, and that is critical.

      Power generation on an inflowing tide is possible, but not efficient. It reduces the amount of water that will enter the embayment, and it acts under lower pressure, or at least, the operators would have to wait until nearer high tide so that there is a decent head of water outside the barrage to load the pressure on, but there is a strong element of “diminishing returns” here. On the other hand, it would extend the effective generating period.This is covered in research report 3 of the SDC report, and I don’t have any evidence to contradict their findings.

      You cannot ignore those fluctuations in the tidal patterns, they too form part of the equation. For example, I believe the biggest tide of the last year about a metre at Sharpness smaller than that of the previous year (not sure about that, but I think it’s in the ball-park). Now going back to my previous post about water levels, that actually represents a massive reduction in power generation potential.And those spring tides only occur for a couple of days every two weeks. Today, the tidal range was only 6 metres at Sharpness, and about 7 metres at Bristol. As a silt alleviation method, I believe it is proposed that the turbines be set a little higher up the barrage wall. I don’t know how high, but let’s say a modest 2 metres. Then factor in that Prof Roger Falconer, who seems very much pro-barrage, says that a barrage will reduce the tidal range to some extent.. I don’t know his figures, but I think you can see where I’m going with it…how much tide will actually be generating power, even on a big spring tide?

      Why did this proposal even get this far?

      There are other options which are available now, today. Why are we not looking at them the way we’ve been looking/wasting time on tidal range?

      Tidal fence? No. Good idea, but almost as bad for siltation as a barrage. Go to Sharpness on one of the days when they have to clear their breakwater (which is effectively a fence) of silt. See it for yourself.

      Tidal stream turbines: many won’t work in most of the Severn estuary because it is too shallow for them, but there are designs that will, and that can be placed in numerous locations. Lower maintenance, less environmental damage,no obstruction to shipping (thus removing the fairly powerful anti-barrage lobby of the Bristol Port Company)..what’s wrong with that?

      The tidal reef structure is one I find fascinating. In theory, it seems to be sound thinking. It operates on a low head of water, so the natural flows are less obstructed. For the most part it’s under the water, so there’ll be less nimbyism on the score of ruining anyone’s view. I don’t know if it will cause a siltation problem, but as the stated aim is to extract less energy from more water over a longer period, I would imagine that silt WOULD be an issue, but on a much reduced scale.

      One last point. If/when the gulf stream stops, and we get a tad chilly over here, silt will be much less of a problem. It will still occur, but the flocculation process which makes it such a problem will be interrupted, as those organisms won’t beable to have the same effect on the mud at greatly reduced temperatures. It isn’t a problem where ice, or glacial melt-waters are prevalent.

      Personally, Strangford Lough is where we should be looking for inspiration.

      Tidal stream turbines are the way forward, barring any new advances in tidal range technology.

    • adi

      Thanks for your thoughts – I’ve not been following the SDC or vested interests and even if someone did profit from it – good luck to them as long as its the right thing. Trouble with this – is its a huge project to study and I don’t have the time. I’ll try to get clarity on the siltation from Proffessor Twidell – whose opinion I trust and it may outweigh the concerns mentioned by your proffessor. If not, then some kind of “inflow” system seems the next best and you might be right but lets get the views on the table from those still in favour who may have addressed the siltation concerns first. Glad you want something to proceed though, its just how much less energy would the UK get if a barriage didn’t go ahead (I recall the lagoon option was a pathetic contribution to the barriage).

      Merry Christmas anyhow

      Adi

    • Neil Law

      I’m very much in favour of that approach…get the info out there. For me, a barrage is a complete non-starter, because of all those tidal power plant ever built, only one has been anything like a total success. The others have been partial or total disasters.

      When I gained the opinions that I went looking for, I put them into a submission to the Severn SEA. Unfortunately, not being an academic myself, and having only a couple of weeks to do what should have taken 6 months, my submission was full of typos, and didn’t cover half the topics I wanted to include.

      However, the info from Prof Haslett and Dr Daborn was good quality, so I passed it on to Stuart Ballard of Saveoursevern.org, as he seemed better at getting information out there than I am.

      He was already posting information about Moncton on his website, but this quotes Dr Daborn’s report to a proposed project in Australia, which he believes is similar to the Severn, with the exception that what is said about mangrove is pretty much transferrable to areas of saltmarsh.
      http://saveoursevern.org/dr-graham-daborns-report-on-silting/
      With respect Adi, as you say, you haven’t had time to follow all the developments. That is an approach which I characterise as irresponsible,as you are a strong advocate for a barrage without having (apparently) scratched below the surface.
      I don’t know Dale’s approach, but if it is similar to your own, then I say again, it was highly irresponsible to go into print without doing the background work. You seem to be trying to make a round peg fit a square hole..the evidence is right there…barrages don’t as a rule, work.

      My biggest fear is that we take this huge risk and build something enormous which goes belly up, then Joe public says “stuff renewables..huge cost…didn’t work…lets go nuclear” etc.

      But on the other hand, I welcome the chance to exchange views with anyone who is as passionate about renewables as you seem to be. I’m right with you on that.

      Cheers

      Neil

    • adi

      Hi Neil,

      I take your point that it could put people off if it failed (note thought that R & D usually follows a path of a few failures before success).

      What is odd though is that you continue to only represent the side which objects to the Severn barriage. If you are right and there is no technical solution I’ll be right behind you but you have not demonstrated to me that you have looked around for solutions to the siltation.
      That could also potentially be irresponsible – what if there were really a solution you were unaware of and yet you played a part in preventing it by putting people off?

      Let just a agree that we both want that tidal power to be harnessed in an effective way and if I get time to research what solutions to siltation there are which go beyond previous experiences/models then I’ll post these up later.

      Adrian

    • Neil Law

      Adi, I’m looking where the evidence points, nothing else.

      Direct the Professor to the link I provided above on Dr Daborn’s conclusions. He suggests that the critical error is that in these situations, engineers tend to disregard the impact of particle size and biological factors.

      When someone can show me why we won’t have another Moncton here, I’ll be a lot closer..not quite all the way, but a lot closer to believing that a barrage is a good option.

      Seagen is looking good,and could be used right now from the available evidence.

      Have a great christmas.

      Neil

    • Rupert Armstrong Evans

      As the builder of the first ‘Tidal Stream Turbine’ in the UK and the designer of the ‘Severn Tidal Reef’ I can tell you a little of how the project came about. I consider it a tragedy that that ‘greens’ should be fighting ‘greens’ when it appeared that there was an engineering solution. I took as my starting point that the scheme should be as environmentally benign as possible, with no significant impact on wading birds, migratory fish or shipping. A tall order but posssible! Most of the potential damage arrises because of the high differential in water level required by conventional turbines. I first wanted to establish the validity of a low head structure (that tracks the full tidal range) and W S Atkins has just completed a report commissioned by the RSPB that confirms tha the ‘Reef’ could generate more power than any of the other options under consideration. They went on to say that it could be £2bn cheaper (costed using conventional technology) than the Cardiff-Weston Barrage. I regret that I don’t agree with Dale Vince in supporting the barrage scheme as the ‘Reef’ should be a far greener option and now has the support of many of the environmental groups. It is a very important project and I only hope people are prepared to cooperate rather than fight.

    • Neil Law

      Rupert,

      Your proposal intrigues me,I have to say. I managed to get an understanding of silt transportation issues only with the help of Dr Daborn,but that was in reference to barrages. I must admit I haven’t the faintest idea how the reef would work in this respect. Have you taken any account of the Moncton scenario? Or do you have any reason for believing that sedimentation will not be a problem?

      I get the general idea that the reef extracts less energy from more water,but will this mean that there will be specific areas which are more likely to show a significant amount of deposition?

      Regards,and happy new year

      Neil

    • Richard Ash

      I was very disturbed to to hear about this blog post (which has been widely reported, almost entirely without the note on ecological impact), and reading this doesn’t do anything to allay my fears.

      To link generation of less than 5% of UK electricity consumption with elimination of Fuel Poverty is disingenuous. Fuel Poverty is a major issue, but is almost entirely due to the abysmal quality of our national housing stock and the appalling quality of the heating systems fitted to many of them. To fix this would be neither cheap nor easy, but it would be a very effective way to invest government money, because the energy savings would last for years, and free up sustainable energy production for other essential uses (for those who doubt the effect of energy efficiency work – we replaced a 20 year old boiler and controller with a new one, and saved 60% on our gas bill straight off, despite heating the house all day).

      Siltation is only one of the issues that a barrage has to address. Equally important is the vast energy cost of the concrete and other materials needed to construct such a barrage. Studies have suggested that the carbon cost of making the cement needed may well exceed the emissions from generating the whole of the barrage’s electricity (over it’s predicted life) from fossil fuels directly (no-one has yet managed to make cement economically without carbon fuels of some sort). As the recent Mersey Estuary study (http://www.merseytidalpower.co.uk/) showed, there are many possible technologies for extracting energy from the tides, and barrages are really outdated technology with big problems.

      Finally, plans already exist (and have funding) for marine current turbines in the Skerries tide-race near Anglesey (http://www.marineturbines.com/18/projects/20/the_skerries/). This is currently a small scheme, but there is massive further potential to generate power from tidal flows around the UK.

    • simon mallett

      Some of the earlier contributors touched on Flood alleviation, certainly with rising sea levels we will have to look at the increasing use of flood defence barrages in major estuaries, surely far better to combine them with energy generation. As to the timescale – its always 100 years in the future. But, reading Dr Stammer’s work on the global movement of seawater and meltwater, particularly from the Greenland icecap, in particular that it can take decades for meltwater to migrate round the world, it might be that the ‘catastrophic’ effects will be seen sooner than expected. A Severn Barrage, along with a Thames and other barrages will then be an urgent project with little if any argument as to the local environmental effects! Lets do it sensibly now rather than desperately in 20 to 30 years time!

    • Neil Law

      Dale, unfortunately I don’t have any faith in Mr Porritt or the SDC on this issue. As I said earlier, I have read turning the tide, all of the main report, and most of the research reports, and I don’t believe the document has sufficient credibility to be the basis of anybody’s policy.

      Simon, Tidal barrages which have gone wrong, and almost all of them do, are a CAUSE of flooding. The evidence is there if you want to look for it. Start in the Minas basin and Bay of Fundy, and you will find it for yourself.

    • Pual Glendell

      Like Neil Law I think the Severn Barrage is a crazy idea. I spent a lot of time around 20 years ago as the energy campaigner for Friend of the Earth Bristol campaigning against it then and as far as I can see nothing has changed since.

      There are many points that I could bring up but perhaps one from the building of Avonmouth Docks will make a good point. The piers at Avonmouth docks were designed by computer, redesigned by computer as they were being constructed so to prevent the silting up of the docks. Within months of the docks opening a contractor was employed to remove silt.

      There are so many other things that can be done apart from building a wall across the estuary to produce power that are a great deal more benign that the barrage is crazy.

      Dale you do some great work and have some very good ideas but this one is crazy!

    • Chris Walker

      I can’t believe that you build wind turbines & then support the Severn Barrage. Listen to your own arguement it will last 100 years, what a huge waste. Tidal turbines placed around the Whole UK coast could produce all the energy this country will ever need & if the engineers put in the effort to build them to last like the Victorians did, then they will last pretty much forever with minimal maintenance & produce constant predictable energy. How many wind turbines do I see parked for maintenance, because they are designed & built CHEAP rather than to do the job required with ZERO or Very low maintenance ? lots.

      Go tidal & forget barrages, they consume vaste amounts of energy to build & the Severn will silt it up very quickly once the flow is killed off, not to mention that barrages only produce power for limited periods during the day & those periods vary with the tides ! So nothing about a barrage is sustainable or predictable.

      Chris W.

    • Adi

      To Chris.

      The next 10 years is critical to curbing climate change which could make <60% of species extinct! So even if it were a bridging step (excuse the pun) it would be worth building the barriage for 100 years providing the carbon impact of building it was significantly less than the CO2 saved.( Ia ctually believe that with correct flow control, the siltation issues is managable and the life of athe barriage would be much longer).

      Any substantiation of coastal potential tidal power and devices to harness it which you mention would be appreciated

      If you are goinf to sea, then I thought that wave power with floating devices was better 12.5% of our current UK electricity demand could be provided that way.. probably easier than coastal tidal but I await to hear from you about that.

      regards
      Adrian

    • Chris Walker

      To Adrian,

      I hear what your saying, but don’t believe the barrage could offset the mountain that would have to be torn down & transported to the estuary, not to mention that Cement is one of the largest CO2 producers in the world & there would be many tons of this. The last info I read on cement CO2 output, indicated that an average 3 bed house build puts out 25-30years worth of car use CO2 just from the cement curing, so I’ve no idea what a commercial concrete structure produces, but it will be of many times greater magnitude.

      If you have ever been to sea, or used the coastal waters, you will know that the Tide waits for no man. As far as wave energy is concerned, its a bit hopeless like wind (but good in that it offsets fossil fuel when its working), very variable in output & requires a large over scaling & dispersed installation to avoid the short comings of periods of light to no wind conditions. I’m sure you are aware, no wind = no waves, so two NON producing renewable’s at the same time! OK wave has a lag behind wind, but its NOT consistent, nor predictable, as in guaranteed!

      Tidal turbines for high flow areas were mentioned & linked by another poster, but like offshore wind that kind of structure is both offensive visually (not to me, I like electricity) & obstructive to navigation & thus likely to be involved in accidents. I have a couple of design ideas for high torque systems, designed for low tidal flow areas, thus maximising the tidal potential. These are self contained completely submerged, self cleaning systems that could be tuned to work almost anywhere there is a tidal flow, which is practically everywhere around the UK coast. A 3knot+ current would be sufficient to generate consistent predictable guaranteed power !

      The Severn estuary alone could produce more energy than any barrage system using this technology & it would produce a base load 24×7 obviously with peak periods during maximum tidal flow, regardless of direction & NO siltation problems. In fact areas of obstruction produce localised increases in tidal streams, so rather than a hindrance, they are a potential benefit !

      If you have ever done any navigation, you will appreciate the fact that the tide NEVER stops (slack) everywhere at the same time & can often be running in opposite directions within very short distances. These turbine systems would be more expensive than wind, but with 100% guaranteed power delivery 24×7, its a no brainer.
      I’m fairly certain the cost would be less than the expected outlay on both Nuclear & the Barrage & would produce 100% of the UK’s electricity requirements & as the power would be generated all around the UK, long haul transmission losses would be avoided to boot, saving approx 15% of the energy currently generated, but lost in transmission.

      Just go visit Skomer Island & witness the tide running through the sound between it and the mainland, tidal speed of up to 8 knots, and a visible head of water of 6-8ft difference between the up & downstream sides. Similar streams can be witnessed under the new Severn crossing, where the stream reaches 5-7knots. You could place one of these turbines between each of the bridge legs, where the bridge acts as an obstruction increasing the flow !

      Submerged turbines designed to last, tick all the boxes, no visual drawbacks, can be placed almost everywhere around the coast with no danger to general shipping, other than that trawlers can’t operate in the immediate vicinity, but that just makes the turbine areas marine reserves in effect, which is great for sea life. And they give guaranteed power delivery, which no other distributed renewable source can claim, conventional hydro does not count, as its concentrated & pretty much maxed out in the UK.

      Just a couple of thoughts. Unfortunately I don’t have the means to build, test or assess these systems, but hope to find a company that can.

      Regards

      Chris W.

    • Neil Law

      Another point about barrages..can’t remember if I’ve said this before or not.

      Even the Sustainable development committee’s Turning the Tide report accepts that barrages start , on completion of construction, at their best level of efficiency , and this reduces from that point onwards to the point where they are no longer viable. We might argue over how long the lifespan is, but the principle essentially remains. They are therefore inherently NOT a renewable source of energy.

      Secondly, if you place a barrage across an estuary, that’s it. You can’t feasibly backtrack and decide to do something else instead, because the presence of the structure prevents you from doing so. With tidal stream technology on the other hand, you can.

      Individual turbines can be placed, added to with more arrays of turbines, taken out of service for maintenance or when a better version becomes available to increase efficiency etc.

    • Roger Barnes

      Having read the contributions to this debate so far, can I add just a few comments from someone in the building industry who has sailed many times in the Bristol Channel and up the River Severn?

      The current proposals for a barrage for a location across the Bristol Channel, and not the River Severn. The dividing line between the River and the Channel is at Avonmouth. All the current proposals are planned to be well downstream of Avonmouth.

      There is no tidal bore in the Bristol Channel, but simply a very strong incoming and outgoing tide. The tidal range in the area proposed for the barrage, (either off Weston-s-Mare, or linking the islands of Steep Holm and Flat Holm), is about 10 metres, which is the second highest in the world. The tidal curve published in the Nautical Almanac, and based on the UKHO survey, is almost a perfectly symmetrical sine wave. It can also be see from the tidal diamonds on the marine chart, that the tidal flows are fairly equal in intensity on the flood and ebb. There is only a very small period of slack water (about 20 minutes) between strong tidal flows of over 5kn.

      Many of the strong opponents to a barrage in this debate would seem to be using incorrect figures, perhaps based on previous proposals for a barrage across the River Severn, rather than the Bristol Channel. That they are presenting manifestly information about the tides in the Bristol Channel, and have not even bothered to check readily available tidal information on the local Charts and Almanacs, makes me very dubious of their authority.

    • Roger Barnes

      Apologies for the typos in that last posting. My computer battery went flat in the middle of posting it, which threw me completely! But I hope the sense was clear.

    • Alexander Cleminson

      Hi Dale
      As a long time Ecotricity customer I think getting energy from the Severn sounds like a good idea.

      BUT as a ‘green leader’ it would be great to have you supporting the tidal stream option, rather than what is in effect a dam on one of Britain’s finest ecosystems – something the UK has condemed in its World Commission on Dams. Damaging dams are now being built across Europe in the name of climate change.

      Why rob Peter to pay Paul when there’s a less harmful alternative.

      Alexander

    • Neil Law

      Roger,

      I agree that there is no tidal bore in the Bristol Channel. From what I can glean, it seems to show it’s first signs around Beachley.

      However, you are factually incorrect about the siting of the shortlisted proposals. The Shoots Barrage is also pretty much adjacent to the second crossing, just downstream of Beachley. In my view it is the proposal likely to be the most short-lived, as the silt load is just about at it’s highest at the same point.

      I note that there is a proposal for a feasibility study into another barrage on the Loughor estuary, just north of the Gower peninsula.

      But (to my mind) more positive news comes from Morecambe bay, where there is now a plan to trial one of the newer designs of tidal stream turbine, which seems to be under consideration instead of the (previously considered) barrage.

      Neil

    • Kate

      Am I the only person that doesn’t agree with saving the planet at the expense of its environment? I would rather there was an end than continual intentional destruction at the hands of man. That’s not a world I want to live in.

      I believe we are close to finding a way to capture the energy of river tides without mass destruction of its function and ecology, through the use of modular tidal stream turbines which I fully support.

    • Neil Law

      Kate, the answer to your question is simply no, you’re not the only one. As I ( and I believe many others) have stated here, that doesn’t seem right at all, that we should destroy our environment to save it in some way. It seems to be a singular failure to learn from the past.

      To be fair, I think that many people from all apparent sides of the debate have the same motivations, but maybe take a different view on how exactly to protect the environment.

      If you have been following the consultation process closely…and reading the small print of the govt’s statements.. you might have noticed that there were, prior to the public consultation stage, 79 principles to be met by any succesful scheme. The govt, as a result of that last stage of consultation, added an 80th condition. That states that the Severn Bore must not be significantly affected.

      Whilst that might seem only to be good news for bore surfers and sightseers, it’s actually a lot more than that. The research of Dr Hubert Chanson makes it pretty clear that highly silt-loaded estuaries with tidal bores have a natural system of silt management, and that is the tidal bore itself. This research was put before the inquiry by a friend of mine, Dave Butterton, who secured extensive help from Dr Chanson with his submission.

      It seems to me that academics from around the world are queueing up to make their opposition clear to the current proposals. Somehow it seems that British engineers and academics are of the opinion that they know more than the rest of the world, including those who have actually attempted tidal power generation.

      Hypertidal estuaries such as the Severn, and tidal bores in particular, are potentially very dangerous things.My opinion is that we’re playing with fire, and the people holding the matches are children.

      Neil