David Hansen wrote:
On Sun, 07 Dec 2008 12:40:28 -0500 someone who may be Neon John
wrote this:-

People just don't understand the magnitude of the energy problem.

Don't assume that anyone who disagrees with you, "just don't
understand the magnitude of the energy problem."

No form of electricity generation produces electricity continuously
at full output. It is necessary to understand their individual
foibles to understand the issues.

"Different types of generators operate at a range of capacity
factors - during 2004, gas power stations had a capacity factor of
around 60 per cent, nuclear 71 per cent,

CANDIU reactors, and most modern reactors are around 90-95%. Because
they are reliable, and cheap, they are used for baseband.

hydro 37 per cent, pumped
hydro 10 per cent, and coal 62 per cent. Meanwhile, the overall
average capacity factor (or load factor) for the UK electricity
network is around 55 per cent.

"Clearly this does not mean that the UK electricity network only
operates for 55 per cent of the time, and that the remaining 45 per
cent of the time no electricity is generated! What this figure means
is that all the generators connected to the network produce in a
year a little over one-half of their theoretical maximum output.

"Why does this occur? The main reasons are that electricity
generators must be switched off for planned maintenance, that
mechanical failure forces generators to be switched off at times,
but also that generators will only be run if there if there is a
demand for the electricity they are producing.

"As a result, it is not possible for any generator to achieve a 100
per cent capacity factor - to do so would mean a perfect operational
record, without a single hour of down-time due to maintenance or
mechanical failure, and an electricity demand level that never
varied. This has never been achieved on the UK (or any other)
electricity network."

no, but 90% has been achieved with nuclear reactors.



http://www.shetland-news.co.uk/opinion/energy/response_1_confusion_over_wind_capacity.htm
and it was written by someone who knows a little about electrical
systems.

Pumped storage systems were and are expensive to build. They were
built because when nuclear stations conk out, because of their size,
they leave a large hole in the electricity supply. Because they are
very slow to react, other nuclear stations cannot cover this hole.
Because of the magnitude of the hole, coal fired plants cannot cover
it in the short term. What is needed is something which will start
almost instantly and cover the hole for long enough for coal fired
plants to be wound up. That is a hydro plant. By making it a pumped
storage plant the excess electricity produced by nuclear plants can
be absorbed overnight and it can have a far higher power output than
a "simple" hydro plant would have for an equivalent volume of water.


Complete ********. Dinorwig was not built to back up nuclear power
stations. It was built to even out the peak to mean of daily load.

It i somewhat cheaper given its geography, than an equivalent sized gas
turbine installation.


A good example of such a plant is Dinorwig, which can produce as
much electricity as a nuclear power station within seconds, using
just four of its six units http://www.fhc.co.uk/dinorwig.htm. In
order to perform this trick the turbines must be spinning in air,
synchronised with the external system. When doing this they either
take a little electricity from the external system, or they take a
little of the output of another turbine. From a standing start it
may take as long as a minute to produce full output, though I guess
45 seconds is more typical.