Groups: rec.autos.tech, alt.energy.renewable, sci.environment, alt.global-warming, sci.environment
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BobG wrote:
> This site has a table of energy density by weight and volume and
> compressed air is worse than batteries. (Hint... most air compressors
> I've seen are big noisy 220V several HP contraptions and they huff and
> puff and finally shut off at a whopping 150 psi.)
> http://xtronics.com/reference/energy_density.htm
Your ref:
Compressed Air (no pressure indicated) 17 Wh/l 34 Wh/kg
http://en.wikipedia.org/wiki/Energy_density
"compressed air at 20 bar" 0.27MJ/kg
1MJ/Kg is roughly 278Wh/kg
1 bar is about 14.5psi
Thus the limit appears to be 75Wh/kg at 290psi (about 3 times that of a
lead/acid battery)
However:
http://www.futurepundit.com/archives/000129.html
"the air is both cooled to minus 100 degrees Centigrade and compressed
to 4,500 pounds per square inch"
http://www.activepower.com/files/whitepapers/TACASWhitePaper.pdf
"TACAS begins with compressed air stored in conventional gas cylinders
or pressure vessels. In order to meet the system's performance
targets, it is necessary to store compressed air at high pressures,
ideally 4500 pounds per square inch (PSI) or more. These pressures are
routine for Self-Contained Breathing Apparatus (SCBA) compressors and
fill stations used by fire departments and diving operations. Gas
cylinders rated up to 6000 PSI are widely available."
This is one of the resulting products - an 85kW (for 15 minutes) DC UPS
supply
http://www.activepower.com/files/products/AP_Spec_CoolAir.pdf
A car needs to be able to run for 300+ miles at 60mph using the power
equivalent demand of 30-50kW, a total energy storage/delivery of about
200kWh. Thus a unit only 10 times more efficient could power a car.
I realise that the UPS shown is 1270kg on its own, but it has redundant
extras to maintain storage and produce millisecond response times that
a car storage/power unit would not need. The proposed system could
easily be designed to weigh less than an engine and fuel tank combined.
So try not to write the system off with so little understanding of the
facts.
Comments (1)
Answer Blip said
at 12:59 am on Feb 2, 2010
We are in need of people to answer our communities questions about car repair on various models if someone from your community would like to help out http://www.answerblip.com/car-information-repair-and-facts
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