The message
from The Natural Philosopher contains these words:

10% of 30% is still only 3% of the total energy consumed by this country.

That is a VERY high price to pay - the complete destruction of a unique
ecosystem - for 3%.

What is unique about it and why do you think it would be completely
destroyed.


It is IIRC the HIGHEST tidal range estuary in the world..thats pretty
unique.

2nd highest I think but from the pedantic point of view pretty unique is
in the same class as slightly pregnant. It is a singular situation, not
a range, and I wouldn't have it applying to a tidal range unless there
was only the one.

In order yo extract power you need to essentially completely alter the
tidal flow through it.

The current proposal appears to envisage losing the mudflats from half
tide outwards.

That is going to lead to a radical change in silt deposition and tidal
scouring..on a level that is probably impossible to predict.

That sort of thing is carefully modelled these days, possibly even on
computers, although I would be happier if they stuck to real modelling
rather than relying on virtual modelling. Changes in silting patterns
can be advantageous in some cases.

It would also - depending on where it is - cause significant shipping
access problems.

A good many ports are served through locks. It is not the end of the
world and it does have some advantages.

Ther are a huge amount of unkopwns in it..enough to make me shy away
from it completely froma isiness point of view.

No real unknown unkowns (to quote Rumsfield).

I think you have been listening too much to the greenies.

I seldom listen to greenies. Its a bit like watching big brother. Or
Copronation street. There is merely the sick fasciantion ofw atching the
inevitable uselessness of people being consistently wrong about
everything and making silly mistakes over and over again without
learning from them.

I don't have the stomach for either of them.

The only thing
likely to disappear completely is the Severn Bore and even that isn't
entirely certain.


Depebnd on how you extract the power.

I don't know where I got the 10% from. The most widely used figure seems
to be 5%.


Well thats even more pathetic. ;-)

I might need a rethink on that. The Sinden report that Hanson quoted
compared 10% to 5.3 GW of conventional generator capacity and 13 GW of
Wind generator capacity. Wikipedia (again) gives the maximum output of
the 3 most promising lines for the Severn Barrage as 1 GW, 8 GW and 15
GW but enough information to complete the picture is not given at the
same place but a recent scheme was predicted to give 8.64 GW max, 2 GW
average and be 6% overall so 15GW probably does match the 10% I quoted
earlier.


Whenever I do an internet search these days Wikipedia always seems to
come close to the top. I don't know how biased their entry on the Severn
Barrage is but a look at who is backing the project and who is opposing
it may be significant.

In one corner assorted politicians plus James Lovelock. In the other
mostly the massed (but thin) ranks of the green persuasion plus Lord
Sainsbury.


It will fail on cost probably. Given the choice between investing a
fairly stable and predictable amount in a nuclear power station whose
impact is low and known, and whose costs and output are withing limits
very predictable, and a Severn barrage, whose planning would be
uncertain, whose costs are essentially almost completely unknown, and
whose actual operational efficiency is also a complete unknown, no one
is going to put billions into it unless its not their money.

I would NOT especially eel comfortable about investing in anything that
has to run for years ins a salt water environment..'we've had to pull up
all the turbines to cook the limpets and cockles off them sir'

yeah right..

I suspect that is more an issue with off shore wind power.

I cannot off hand think of ONE commercially successful operating tidal
power project. Tho ISTR plenty of 'pilot ones' that never seemed to
attract large scale investment.

The Frogs have been running one sucessfully for years.

There is always a huge risk in doing a 'first' - look at the Chunnel.
Hardly able to pay its interest payments, let alone make any money for
its investors..

If the ferry operators had been competing for business (and hence not
had outrageous margins) before the advent of the Chunnel the Chunnel
would had been a success at least until the tax favoured budget airlines
got in on the act.

--
Roger Chapman