Severn Barrage brought up again

No doubt some firm of consultants will walk away with yet more millions of public money then it will be kicked into touch for the same reasons it has been in the past.
 
The answer is so simple. Lines of turbines on the sea bed all the way up the estuary. No barrage, constant power as the high tide line moves. Generation both in and out. No environmental impact other than on the sea bed. Obviously too simple and not enough back handers!
 
I would be interested to see what plans they have for locks. Will we be in with the ships or will there be a small vessel lock?
Allan
 
PCUK said:
The answer is so simple. Lines of turbines on the sea bed all the way up the estuary. No barrage, constant power as the high tide line moves. Generation both in and out. No environmental impact other than on the sea bed. Obviously too simple and not enough back handers!
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Very true they say the speed of the tide is stronger on the sea bed
 
I suspect the likely growth of aquatic leisure activities has never been adequately built into any of the countless Severn barrage studies; the taming of the Severn's fearsome tidal flows inside the barrier would create a watersports facility that would make the Solent look pokey in comparison, the potential economic impact of that could be vast.

PCUK said:
The answer is so simple. Lines of turbines on the sea bed all the way up the estuary. No barrage, constant power as the high tide line moves. Generation both in and out. No environmental impact other than on the sea bed. Obviously too simple and not enough back handers!
Click to expand...

If it was simple building subsea turbines we would be subsidising them like we're subsidising whirligigs. There's nothing simple about any of it, except perhaps Peter Hain! :D

The major stumbling block is that it will cost the same as 2-3 nuclear power stations, take 2 decades to build and generate the equivalent of one nuclear power station. Improving road and rail communications between the west country and south Wales and economic growth from watersports will need to be balanced against the extra cost and the perceived and actual environmental cost.
 
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penfold said:
I suspect the likely growth of aquatic leisure activities has never been adequately built into any of the countless Severn barrage studies; the taming of the Severn's fearsome tidal flows inside the barrier would create a watersports facility that would make the Solent look pokey in comparison, the potential economic impact of that could be vast.



If it was simple building subsea turbines we would be subsidising them like we're subsidising whirligigs. There's nothing simple about any of it, except perhaps Peter Hain! :D
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I don't think, apart from travelling through, it will make much difference to us who sail there. To create the power they will have to allow the level inside the barrage to raise and lower, just as it does now. The only difference I can see is the delay they would have to introduce to provide enough "head" for the turbines to work. That delay may increase the settlement that causes such a problem at places like Watchet.
Allan
 
Allan said:
I don't think, apart from travelling through, it will make much difference to us who sail there. To create the power they will have to allow the level inside the barrage to raise and lower, just as it does now. The only difference I can see is the delay they would have to introduce to provide enough "head" for the turbines to work. That delay may increase the settlement that causes such a problem at places like Watchet.
Allan
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I'd have thought that when what are now raging torrents are reduced to perhaps 1-2 knots peak flow there will likely be a great expansion in watersports.
 
I'm not sure I would agree, in two ways.
One is that I don't consider there to be "raging torrents". There are strong tidal streams but these are a positive thing and a great help in passage making.
The other is that to get the energy levels they are predicting they cannot reduce the tidal flows significantly. After all it is the power of those flows that makes the scheme look so good.
Allan
 
Allan said:
The other is that to get the energy levels they are predicting they cannot reduce the tidal flows significantly. After all it is the power of those flows that makes the scheme look so good.
Allan
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Not really; the energy is in the head of water. The flows would matter if it was an array of subsea turbines, but barrages work in the same way as dams; head matters.
 
penfold said:
Not really; the energy is in the head of water. The flows would matter if it was an array of subsea turbines, but barrages work in the same way as dams; head matters.
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I totally agree with that. Therefore to use that head to produce maximum power they will have to let all the water out whilst there is a height difference i.e. within the ebb. During the flood it works in the opposite direction. The difference between a tidal barrage and a dam is the time you have a usable head is restricted. The only way they will be able to use a significant amount of the obvious tidal power is to delay the tides within the barrage to create a head. If they halve the tidal streams on the ebb, they will only be producing half of the power and will still have half the tidal water inside, thus not have the head (difference) for producing power on the flood. I hope that makes sense?
Allan
 
Good link Graham. I see that this site talks about siltation problems, which was a topic of conversation with my neighbours over the weekend in Watchet. You have to wonder what the impact of reducing the water velocity upstream on the barrage on the deposition rates of mud/ silt. I am also concerned at the mortality rates of migrating fish as they pass through the turbines 40% mortality per pass would lead to the extinction of the Severn and Wye salmon stocks, which WAG reckon is worth over £10 million per annum to the Welsh economy. The Severn and Wye salmon is a genetically distinct sub species, which the barrage would make extinct in less than 10 years.

I agree with those who argue that the tidal streams are a benefit to the yachtsman, and that there are alternatives to a barrage which would be less damaging to the estuary. I think that building the barrage would run into difficulties with the EU, particularly concerning the Habitats Directive. The estuary is one of the most important intertidal habitats in Europe and the barrage would destroy many of the features which make it so special.

The money would be better spent on energy conservation and efficiency projects. McKinsey and partners completed a study several years ago which argued that energy efficiency projects were much more cost effective than green energy generation such as wind turbines, tidal and solar. So, spending the cost of the barrage improving domestic and commercial building insulation, energy efficient lighting, and improved public transport would be much better value for money!
 
If the Severn Barrage could generate 25%of UK electricity need maybe it would be worth taking such a massive environmental gamble , can it be wise to take that risk for just an estimated 5% of our electricity?
 
Allan said:
I totally agree with that. Therefore to use that head to produce maximum power they will have to let all the water out whilst there is a height difference i.e. within the ebb. During the flood it works in the opposite direction. The difference between a tidal barrage and a dam is the time you have a usable head is restricted. The only way they will be able to use a significant amount of the obvious tidal power is to delay the tides within the barrage to create a head. If they halve the tidal streams on the ebb, they will only be producing half of the power and will still have half the tidal water inside, thus not have the head (difference) for producing power on the flood. I hope that makes sense?
Allan
Click to expand...

The use of a separate 'pond' to produce a suitable head near HW was
part of an old plan (60/70s? - I remember seeing it in the South Wales
Argus) and the fact that there is a lot more "ebb" than there is flood tends
to maintain that head. As regards the impounded level at any time there will probably be some consensus on the max and min levels. Having visited
La Rance Barrage shortly after it was completed I believe that if the operators wish to lower the "normal" levels by more than one metre (or so) they have to give a goodly warning period. That barrage is different, of
course, in that it is like the Bay - clear (ish) water - little silt!

I used to be in favour (1960 - 1996) of a barrage but it was "proved" by
others and finally admitted by TPTB that the Usk would silt-up if they
had built the then planned barrage just above the Transporter Bridge.
(There again, too many seabed turbines could cause siltation.)
<fx> Ducks back behind parapets.

Doug - Jekeeda II - another W33
 
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