On Sun, 2 Mar 2008 11:14:59 GMT someone who may be Roger
wrote this:-

And not so long ago two turbines self destructed.

Even if the two turbines had a rated capacity of 2MW that left
rather less of a hole in the electricity supply than the failure of
IIRC a 2400MW coal fired station.

Relying on wind for more than a small
proportion of total capacity is a recipe for disaster.

It is over 8% in Scotland now.

Even the
proponents of wind power were saying until recently that 20% was the
practical limit

Incorrect. What people have said is that, at the costs of the time
the reports were done, accommodating more than around 20% was
possible, but the costs of doing so would make it uneconomic.
http://www.sd-commission.org.uk/publications/downloads/Wind_Energy-NovRev2005.pdf
Section 3.5

"It should now be clear that accommodating significant amounts of
wind capacity on the electricity system is not likely to pose any
major operational challenges, and this view has been confirmed by
the GB system operator, National Grid Company. It is also the
conclusion of a comprehensive report on this issue commissioned by
the Carbon Trust and DTI25. At higher wind penetrations, the
capacity value of wind is indeed reduced, and this does lead to
additional balancing requirements. However, this represents a cost
rather than a barrier, as additional reserve requirements will lead
to an increase in systems costs – this is explained further in
Chapter 4."

If you think that shutting down power plants because of lack of demand
or even for routine maintenance or repair is on a par with the weather
shutting down wind turbines either because of oversupply or under supply
of wind you really do deserve your reputation for not thinking things
through.

Excellent, personal abuse.

In fact all power plants shut down or are shut down from time to
time due to sudden unexpected failures, either of the plant itself
or the connection from the plant to the rest of the system. Cracks
in nuclear stations and broken coal conveyors for example. Before
say the 1930s it was typical of councils/electricity companies to
maintain capacity at least double the maximum demand, to cover
sudden failures. By linking the stations together it was possible to
pension off some elderly capacity, without affecting the loss of
load probability.

There was a similar programme in the (Scottish) Highlands later on
to link the formerly islanded electricity systems. For example the
Kyle of Lochalsh was fed exclusively from a station at Morar. In
this case it allowed a higher level of supply to be provided while
maintaining the same reliability. It also allowed greater
flexibility for maintenance.

Those who wish to inform themselves on this subject before launching
into statements on it would do well to first study and understand
the report which can be downloaded from
http://www.ukerc.ac.uk/ResearchProgrammes/TechnologyandPolicyAssessment/TPAProjectIntermittency.aspx


--
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