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Java Jive wrote:

Last time I looked, nuclear, gas, and coal were only around 30%
efficient at turning steam into electricity.

That must have been a long time ago. Gas stations tend to run at about
65% efficiency AFAIK. Coal has been over 40% efficient (on the terms you
appear to use) since the 1960s. AGR nuclear is 41% efficient. PWR
stations like Sizewell B (and most other PWR stations in the world)are
around 28& efficient.

A lot depends on the steam temperature in coal and nuclear stations.
This can be over 560C in Coal and AGR stations.

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

?John Wright

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In article ,
John Wright writes:
Java Jive wrote:

Last time I looked, nuclear, gas, and coal were only around 30%
efficient at turning steam into electricity.

That must have been a long time ago. Gas stations tend to run at about
65% efficiency AFAIK.

The best new ones nowadays can be 60%.
The "dash for gas" stations installed in the UK when we
had dirt cheap gas were cheap gas stations, low efficiency
by today's standards at mostly around 40%, and that's the
bulk of what we have today.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

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In message , Andrew Gabriel
writes
In article ,
John Wright writes:
Java Jive wrote:

Last time I looked, nuclear, gas, and coal were only around 30%
efficient at turning steam into electricity.

That must have been a long time ago. Gas stations tend to run at about
65% efficiency AFAIK.

The best new ones nowadays can be 60%.
The "dash for gas" stations installed in the UK when we
had dirt cheap gas were cheap gas stations, low efficiency
by today's standards at mostly around 40%, and that's the
bulk of what we have today.

How do they achieve that?

I thought there is a limit on steam conversion due to latent heat
issues. Somewhere around 44%. A few losses in the alternator as well.
Magneto thermo dynamics were being investigated 45 years ago but I never
heard of any success.

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:-)

I know nothing about gas turbines.

regards


--
Tim Lamb

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In article ,
Tim Lamb wrote:
In message , Andrew Gabriel
writes
In article ,
John Wright writes:
Java Jive wrote:

Last time I looked, nuclear, gas, and coal were only around 30%
efficient at turning steam into electricity.

That must have been a long time ago. Gas stations tend to run at about
65% efficiency AFAIK.

The best new ones nowadays can be 60%.
The "dash for gas" stations installed in the UK when we
had dirt cheap gas were cheap gas stations, low efficiency
by today's standards at mostly around 40%, and that's the
bulk of what we have today.

How do they achieve that?

I thought there is a limit on steam conversion due to latent heat
issues. Somewhere around 44%. A few losses in the alternator as well.
Magneto thermo dynamics were being investigated 45 years ago but I never
heard of any success.

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:-)


the 'waste' heat at Portobello - Edinburgh 1930s - was used to warm the
outdoor swimming pool.

--
From KT24

Using a RISC OS computer running v5.11

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Tim Lamb wrote:
In message , Andrew Gabriel
writes
In article ,
John Wright writes:
Java Jive wrote:

Last time I looked, nuclear, gas, and coal were only around 30%
efficient at turning steam into electricity.

That must have been a long time ago. Gas stations tend to run at about
65% efficiency AFAIK.

The best new ones nowadays can be 60%.
The "dash for gas" stations installed in the UK when we
had dirt cheap gas were cheap gas stations, low efficiency
by today's standards at mostly around 40%, and that's the
bulk of what we have today.

How do they achieve that?


IIRC and I am not sure I do :-) Its by using a front end gas turbine -
jet engine - which can cope with thousand degree working
temperatures..then the exhaust from THAT feeds the boiler and off to a
condensing steam turbine..


I thought there is a limit on steam conversion due to latent heat
issues. Somewhere around 44%. A few losses in the alternator as well.
Magneto thermo dynamics were being investigated 45 years ago but I never
heard of any success.

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:-)

I know nothing about gas turbines.

I know a LITTLE more, but not enough..



regards

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On Wed, 7 Oct 2009 08:52:16 +0100, Tim Lamb wrote:

The best new ones nowadays can be 60%.
The "dash for gas" stations installed in the UK when we
had dirt cheap gas were cheap gas stations, low efficiency
by today's standards at mostly around 40%, and that's the
bulk of what we have today.

How do they achieve that?

Presumably by not getting all the energy out of the steam by
successive use of the steam from one set of turbine blades to
another. Multi-stage turbines are expensive...

I thought there is a limit on steam conversion due to latent heat
issues.

Any one with any sense would condense the low pressure steam from the
last turbine using the latent heat thus released to preheat the water
going into the boilers. But again this cost money...

Gas was a cheap by product of north sea oil no point in building
highly effcient but expensive power stations when the fuel is a cheap
"waste" product.

--
Cheers
Dave.

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In article , The Natural Philosopher
wrote:


IIRC and I am not sure I do :-) Its by using a front end gas turbine -
jet engine - which can cope with thousand degree working
temperatures..then the exhaust from THAT feeds the boiler and off to a
condensing steam turbine..

IIRC There was a report in IEEE Spectrum a year or three ago about an error
the USA made as part of their process of re-establishing electric power
infrastructure to Iraq having buchered it during the 'war'.

The 'quickest solution' was to buy and install what were essentially jet
engines as turbine generators. Good method if you want a quick install and
a small physical package to put in place.

The snag was that these required very high grade fuel and careful operation
and maintainance. So kept failing in a post-war situation where the
logistics weren't in place to support this. Still, the contractors no doubt
made a lot of money out of it...

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

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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 ...

André Coutanche

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Jim Lesurf wrote:
In article , The Natural Philosopher
wrote:


IIRC and I am not sure I do :-) Its by using a front end gas turbine -
jet engine - which can cope with thousand degree working
temperatures..then the exhaust from THAT feeds the boiler and off to a
condensing steam turbine..

IIRC There was a report in IEEE Spectrum a year or three ago about an error
the USA made as part of their process of re-establishing electric power
infrastructure to Iraq having buchered it during the 'war'.

The 'quickest solution' was to buy and install what were essentially jet
engines as turbine generators. Good method if you want a quick install and
a small physical package to put in place.

This sort of thing has been done for many years all over the world in a
non CCGT application. In the UK they were used for load lopping - to
counter the momentary increase in power demand seen when everyone turned
the kettle on in the ad breaks in Coronation St. etc. This effect is now
no longer so pronounced as it was thanks to the proliferation of TV
channels.

Virtually every power station in the UK built since the mid-60s has had
a group of 4 gas turbines for this purpose. I've also seen them in use
as main power stations in places that are awash with oil like Bahrain
and Saudi Arabia.

--

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

?John Wright

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The Natural Philosopher wrote:
charles wrote:
In article , [email protected]
wrote:


"J G Miller" wrote in message
...
On Sun, 27 Sep 2009 21:31:57 +0100, The Natural Philosopher wrote:
WE have totally inadequate wind rain and places to generate hydro
pwer.
Then why did there used to be a power utility called The North of
Scotland Hydro-Electric Board which generated and distributed
electrical energy to Northern Scotland?

We have hydro plants on streams that can generate a couple kilowatts, it
doesn't mean we can supply the whole country with clean power. They are
just inadequate for the job.

The above organisation, in its current guise of Scottish & Southern
Energy,
has just commissioned a new 100MW hydro scheme at Glendoe and hopes to
turn
the existing Sloy scheme (at 153MW - the biggest in the country) into a
pumped storage one. so much for "streams generating a couple of
kilowatts"

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.

If you are talking total energy that might be true, but electricity
alone I always thought was around 50-70GW. This seems to be the topic of
discussion.

--

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

?John Wright