David Hansen wrote:
On Tue, 26 May 2009 20:42:41 +0100 someone who may be Andy Champ
wrote this:-

The Natural Philosopher wrote:
its a very expensive and environmentally dfestrictive (sic) way to generate
power, and there are only a few places where its really effective - you
cant use the whole coastline, not for any decent scale and efficiency.
Sure.

Expensive? Compared to nuclear most things are cheap.


No, compared to nuclear every single alternative energy source is *way*
more expensive.

Nuclear electricity generally 2-3p/unit. Wind about 10p.Once the cost of
the transmission lines and grid balancing is costed in (which its
protagonists NEVER do).

Uses roughly ten times as much concrete per average watt delivered as
nuclear too.


Environmentally destructive? What sort of system? A Severn barrage
would certainly largely destroy internationally important wildlife
habitats, though climate change will do that too. Build lagoons
instead and, the proponents say, one can generate at least as much
electricity while still preserving the habitats. The reports at
http://www.sd-commission.org.uk/pages/tidal-power.html discuss the
issues. Offshore lagoons are probably not the thing, but that is
where turbines come in, of which the most well known is probably
http://www.marineturbines.com.

Using the whole coastline?

"The strength of the tidal current varies depending on the position
of the site on the earth, the shape of the coastline, and the
bathymetry (shape of the sea bed). Areas that have high tidal
currents are in narrow straits, between islands, around headlands,
entrances to lochs, bays and large harbours. This flow is cyclical,
first increasing in velocity and then decreasing before switching to
the opposite direction.

"The generation of energy from tidal currents is therefore very site
specific. The World Offshore Renewable Energy Report 2002-2007 ,
released by the DTI, suggests that while a staggering 3000GW of
tidal energy is estimated to be available, less than 3% of this is
located in areas suitable for power generation. A number of possible
sites have been identified in Scotland. The Pentland Firth has been
described as the Saudi Arabia of the world's future tidal industry,
which is capable of providing up to 10% of the UK's energy demand
alone. Scottish Enterprise has estimated that 34% of the UK's
electricity demand could be generated by tidal currents."

http://www.scottishrenewables.com/Default.aspx?DocumentID=27e58172-d6f0-4968-a2ee-3db723d6c093

In the short term I agree with your position - we can either go
fission, or have no power.

If built it would be too little too late. The SD Commission report I
have referred to before explains why.


Same applies to any alternative energy.


But I think tidal is probably a better bet
than wind, and it could provide part of a balanced system.

Wind works now, there is no large scale tidal scheme in the UK
(despite the ROC system being neutral about what form of generation
is used). In the future both will be used, which is great.


Wind doesnt really work at all.

That's the problem.