Clot wrote:
Am I missing something? Our demands on the system have peaks that do not
coincide with the lunar cycle of the tides. We need a mix of electricity
generation that can cope with the variations.

The output of a tidal system is roughly sinusoidal, peaking at half tide.

Add two systems, 90 degrees out of phase, and you have an approximation
to a continuous supply.

Andy

The message
from Andy Champ contains these words:

The output of a tidal system is roughly sinusoidal, peaking at half tide.

Add two systems, 90 degrees out of phase, and you have an approximation
to a continuous supply.

I can't find anything at the moment that predicts the period during
which tidal energy can usefully be extracted but the current front
runner for the Severn Barrage seems to be designed only to generate on
the flow tides. That would leave each flow tide on its own if there were
just 2 systems 90 degrees out of phase.

I presume output could be controlled so that once the barrage starts to
generate it gives even output as much as half the time from low tide to
high tide might be lost waiting for the head to build. One reference
suggested output is proportional to the square of the tidal range* which
suggests they will be going for shorter generating times rather than
longer.

*Not clear to me why that should be the case (I thought mgh would rule)
but no doubt someone will soon be along to point out I have managed to
overlook something really obvious.

--
Roger Chapman

The message
from Roger contains these words:

That would leave each flow tide on its own if there were
just 2 systems 90 degrees out of phase.

Just to set the record straight by the time I posted that I had edited
out my original comment about a 50% hole and rewritten much of the rest
on the basis of 2 systems 180 degrees out of phase. Unfortunately
something very obvious that should have be changed didn't get changed.

Sods law doesn't really fit but surely there must be a Usenet law about
that millisecond between pressing send and the realisation of a stupid
mistake.

--
Roger Chapman

Roger wrote:
The message
from "Clot" contains these words:

Sailing round offshore turbines could be fun.

Ahoy there small sailing vessel approaching down wind. This is the
anti-terrorist protection unit broadcasting on a frequency you won't
be listening to. We have you in our sights and if you don't turn
round and head up wind at least as fast as you are now travelling in
this direction we will blow you out of the water without further ado.
You have 20 seconds to comply with this message. :-)

Yikes - I'm gone!

On Sat, 08 Mar 2008 14:22:36 GMT someone who may be "Clot"
wrote this:-

Sailing round offshore turbines could be fun.

They are rather easier to deal with than sand, as a wind farm stays
in one place rather then shifting around.
http://www.npower-renewables.com/northhoyle/navigation.asp
explains navigation for the first major offshore wind farm.


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

David Hansen wrote:
On Sat, 08 Mar 2008 14:22:36 GMT someone who may be "Clot"
wrote this:-

Sailing round offshore turbines could be fun.

They are rather easier to deal with than sand, as a wind farm stays
in one place rather then shifting around.
http://www.npower-renewables.com/northhoyle/navigation.asp
explains navigation for the first major offshore wind farm.


Until it blows over, or you get fog..plenty of ships crash into solid
immovable objects all the time..

Never mind, you can use the output of them to put lights on them..oh.
Fog=no wind = no lights.

You can't win, with windmills, can you?


Except in la-la land.

On Sun, 09 Mar 2008 18:01:12 +0000 someone who may be The Natural
Philosopher wrote this:-

Sailing round offshore turbines could be fun.

They are rather easier to deal with than sand, as a wind farm stays
in one place rather then shifting around.
http://www.npower-renewables.com/northhoyle/navigation.asp
explains navigation for the first major offshore wind farm.

Until it blows over, or you get fog..plenty of ships crash into solid
immovable objects all the time..

Nice try. However, as usual it is easy to spot the flaws in your
assertions. In this case it is particularly easy to do so by reading
http://www.npower-renewables.com/northhoyle/nav_trials.asp







--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54