On 02/10/2012 16:00, Dave Liquorice wrote:
On Tue, 02 Oct 2012 13:59:24 +0100, The Natural Philosopher wrote:

"excess energy generated from renewables."

hahahaha ROFLMAO.

Well yes. Would get rid of the stupid "we don't want your power but we'll
still pay you your well above market price". Every wind farm has to have
a liquid air plant (paid for by the wind co) to even out the
supply/demand problem.

" this process is only 25% efficient but it is massively improved by
co-siting the cryo-generator next to an industrial plant or power
station producing low-grade heat that is currently vented and being
released into the atmosphere"

So like all renewables it depends on cheap fossil fuel to work.:-)

More green pie in the sky.

But look at it another way instead of having to throttle your fossil
plants up and down with demand which isn't very effcient you can run them
with a steady throttle and dump to (or take) from the liquid air energy
bank to meet demand fluctuations and you have the waste heat from the
power station to help.

I'm also wondering what the energy density of liquid air is. Could it
become a replacement for diesel/petrol in smaller vehicles? We seem to be

If you take it as a 80:20 mix of Nitrogen / Oxygen, you get a specific
latent heat of vaporisation of just over 200 kJ/kg compared to 46.8
MJ/kg if you oxidise petrol. So not an ideal replacement by the sounds
of it.

Which suggests you need 18,000 tonnes of liquid air to store 1MW/h. The
density is about 9/10ths that of water - so 20,000 litres roughly.

In gaseous form that is lots of air - hence you need to vent it rather
than store it after use. It also means stripping the CO2 from "new" air
each cycle.

able to handle LPG safely enough and that is flamable, liquid air is well
air... I can see problems in winter though with frozen "radiators" (aka
heat absorbers) to provide the energy for the phase change.

With LPG you can burn the thawed gas to provide the heat of vaporisation
- and its only a small proportion of the heat stored. The same trick is
unlikely to work for air!

--
Cheers,

John.

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