Switch off at the socket?
 

In message , André Coutanche
writes
The Natural Philosopher wrote:
Tim Lamb wrote:

I know nothing about gas turbines.

I know a LITTLE more, but not enough..

That stirred a long disused neurone, which said 'CCGT'. That led to
http://en.wikipedia.org/wiki/Combined_cycle, and one of its references,
http://memagazine.asme.org/Web/Effic...by_Numbers.cfm . So, yes,
efficiencies can be achieved which appear at first glance to break the laws
of thermodynamics ...

Ah. All is explained.

ISTR the idea of mag. thermo dynamics was to withdraw energy (DC) from
the ionised gas stream in a conventional boiler.

regards
--
Tim Lamb

Switch off at the socket?
 

[email protected] wrote:


"The Natural Philosopher" wrote in message
...

well with a typical power station being somewhere upwards of a Gw, and
our total energy needs as a country running at an estimated 300GW, I
cant see those making a huge difference to anything.

I can, hydro electric are easy to control and respond quickly.
Run them at the bare minimum and you can turn them up to smooth supply
during peaks.
Pretty much like the pumped hydro stations but not as big.

ISTR that Dinorwig could run from zero to full power in about 2 minutes.
Any hydro scheme should be able to do that too.

--

People like you are the reason people like me have to take medication.

?John Wright

Switch off at the socket?
 

The Natural Philosopher wrote:
J G Miller wrote:
On Sun, 27 Sep 2009 22:26:11 +0100, [email protected] wrote:

We have hydro plants on streams that can generate a couple kilowatts

Sounds like Scottish Power generate more than a *couple of kilowatts*
to me
from hydro electric schemes --

Lanark Hydro Electric Scheme 17 MW


About the same as a big diesel generator. Enough to run one electric
train line maybe..

Depends on the electric train. Eurostars IIRC use about 13Mw on 25KV AC
- much less in Belgium or on third rail. (Eurostars are *very* long)
Class 91 trains on the ECML use about 5Mw.

Pendolinos are heavy and "built like a tank" according to Richard
Branson :-) and use just under 6Mw. Class 92s about the same.

The highest power electric trains are the Eurotunnel shuttles, with two
Class 9/8s they will use around 15MW.

So more than one unless you want loads of Eurostars.

--

People like you are the reason people like me have to take medication.

John Wright

Switch off at the socket?
 

The Natural Philosopher wrote:
Java Jive wrote:
On Sun, 27 Sep 2009 21:31:57 +0100, The Natural Philosopher
wrote:
There is nothing centralised about the grid.

Power generation is centralised.

On a level UK playing field, we have plenty of wind and rain, some
sun, and no uranium ore.
WE have totally inadequate wind rain and places to generate hydro pwer.

The field is tilted way against nuclear and way pro wind, that's all.
Whereas historically it has been the other way about.
It has not.

It was tilted massively towards big centralised power generation in
the post-war years, with large government investments in places like
Windscale and Dounreay, and through the CEGB commissioning the first
rounds of nuclear power stations.


Windscale and Douunreay were weapons production facilities thinly
disguised as power stations.

Chapelcross rather than Dounreay I think. What you need for plutonium
production is a fast turn round natural uranium reactor. Hence Calder
Hall and Chapelcross. These two were always owned by UKAEA rather than
whatever organisation ended up with the other Magnox reactors.

AFAIK Dounreay was always a research establishment.

--

People like you are the reason people like me have to take medication.

?John Wright

Switch off at the socket?
 

On Wednesday, October 7th, 2009 08:52:16 +0100, Tim Lamb suggested:

Using waste heat for space heating only works if you have generating
plant in the middle of towns and you don't have warm summers:-)

Metz, Lorraine has warm (compared to England) summers and the CHP there,
one of the oldest in France has worked efficiently and successfully.

http://www.uem-metz.FR/site/_activites_chauffage.php

In 2005 UEM added a second network of 15 km and 88 sub-stations,
with 300 clients.

Switch off at the socket?
 

J G Miller wrote:
On Sun, 27 Sep 2009 16:33:02 +0000, Richard Tobin wrote:

In the standard model, protons don't decay.

Is Wikipedia correct in its assertion that

QUOTE
Proton decay has not been observed.
There is currently no evidence that proton decay occurs.
UNQUOTE

I would say that is true and correct whatever theory you happen to
believe in.

--

People like you are the reason people like me have to take medication.

John Wright

Switch off at the socket?
 

On Wed, 07 Oct 2009 14:30:01 +0100, John Wright
wrote:

snip

ISTR that Dinorwig could run from zero to full power in about 2 minutes.
Any hydro scheme should be able to do that too.

The reality is rather more impressive:
http://www.fhc.co.uk/dinorwig.htm

"Synchronised and spinning-in-air emergency load pick-up rate from
standby: 0 to 1,320 MW in 12 seconds"

One of the design briefs for the station was that it was to be capable
of supplying power quicker than gas-turbine plant, and it was designed
accordingly. This will not generally be true of conventional hydro
schemes.

Brian

Switch off at the socket?
 

"John Wright" wrote in message
...
[email protected] wrote:


"The Natural Philosopher" wrote in message
...

well with a typical power station being somewhere upwards of a Gw, and
our total energy needs as a country running at an estimated 300GW, I
cant see those making a huge difference to anything.

I can, hydro electric are easy to control and respond quickly.
Run them at the bare minimum and you can turn them up to smooth supply
during peaks.
Pretty much like the pumped hydro stations but not as big.

ISTR that Dinorwig could run from zero to full power in about 2 minutes.
Any hydro scheme should be able to do that too.

With the minor problem of how to refill the dam.

Switch off at the socket?
 

Brian wrote:
On Wed, 07 Oct 2009 14:30:01 +0100, John Wright
wrote:

snip

ISTR that Dinorwig could run from zero to full power in about 2 minutes.
Any hydro scheme should be able to do that too.

The reality is rather more impressive:
http://www.fhc.co.uk/dinorwig.htm

"Synchronised and spinning-in-air emergency load pick-up rate from
standby: 0 to 1,320 MW in 12 seconds"

One of the design briefs for the station was that it was to be capable
of supplying power quicker than gas-turbine plant, and it was designed
accordingly. This will not generally be true of conventional hydro
schemes.

Though there is no reason why it need not be.

--

People like you are the reason people like me have to take medication.

?John Wright

Switch off at the socket?
 

Derek Geldard wrote:
On Wed, 23 Sep 2009 10:02:01 +0100 (BST), "Dave Liquorice"
wrote:

On Wed, 23 Sep 2009 03:03:15 +0100, Derek Geldard wrote:

Not true, in fact. All radioactive isotopes decay according to their
half lives. When they're gone, they're gone.
"Half life", the period of time it takes for half of the orginal
substance to have decayed. After that time it's another equal period
for the next half to decay, still leaving you with 1/4 of the orginal
amount.

However it doesn't take many half lives for activity to decay to a
level lower than the natural background, whence it will become
undetectable - and it will still keep on decaying.

In the medical isotope industry it is reckoned that all radiactivity
may be taken to have ceased after 6 half lives. If the half life is 6
hours (TC99m) then effectively it's all gone after 36 hours and a big
dose can safely be injected into a patient for a radionuclide scan.
After 10 half lives the activity is down to about 0.5 per million of
what you started with.

If it's 12,000 years it will be rather longer, but decay it will.

An isotope also has a bilogical half life which is the rate that it
would be eliminated from the body by normal bodily functions.

Of course it depends on the substance how long the half life is, they
vary from seconds to thousands of years but most are fairly short and
the level of radiation decreases over time as well. The nature of the
radiation is important as well, alpha particles are easyly stopped
for example.

Common misconception, along with "If an isotope has a long half life
it's not very radioactive", -erm no 1 millicurie is 1 millicurie .

Very true, but pound for pound there is less radiation from something
with a long half life than from a short one. Hence natural uranium is
normal, but plutonium is warm to the touch. 1 millicurie of each would
be very different in physical weight or even mass.

NB. if high energy Alpha emitting isotopes are absorbed into the body
they do tremendous damage at the cellular level because alpha
particles are electrically charged and lose all their energy over a
very short distance (hence the low penetrating capability). The most
damage is caused when a speck of alpha emitting material lodges in the
body and goes on year in year out irradiating the same tiny volume of
body tissue, cell damage leading to cancer is very likely.

Most alpha emitters also emit beta and/or gamma radiation as well. As
you say they have to be absorbed into the body to create a real danger.

--

People like you are the reason people like me have to take medication.

?John Wright