sci.energy

In article
<20e3b360-717d-4ca5-929d-710a10c5bc26@>,
Bret Cahill wrote:

> > > The Air Car caused a huge stir when we reported last year that Tata
> > > Motors would begin producing it in India. Now the little gas-free ride
> > > that could is headed Stateside in a big-time way.
>
> > It's NOT zero-pollution. ?Something has to power those compressors
> > that fill the tanks in this thing, unless you've got a windmill or
> > solar panels on your roof, you create pollution.
>
> Later they mention an 8 gallon fuel tank. Maybe it's a compressed air
> hybrid and maybe the compressed air tanks can be pumped up
> electrically from the grid ["zero emissions"] for a short trip.
>
> Compressed air stores even less energy than batteries on a specific
> energy basis so, without burning fuel, it's going to be a _real_ short
> trip.
>
> Nevertheless, as a hybrid, it may be cheaper to use compressed air and
> just cycle the ICE on and off much more frequently.
>
> Batteries wear out after so many charges which makes batteries more
> expensive and more fuelish overall than fuel only conventional
> drives. This might not be as true for a compressed air storage
> system.
>
> Compressed air motors and turbomachinery are extremely compact. The
> big thing will be the air tank.
>
>
> Bret Cahill

Bret, there are other problems that have not been addressed. These ‘air’
cars come by every couple of years. What is never talked about by the
promoters is how they will get around the problem of the heat of
compression. Unless this can be stored for use during the expansion or
isothermal compression and expansion are use 75% of the compressors
input energy is lost to the motor output shaft. Add the compressor drive
motor losses and you have a system efficiency of 18 to 20%.
Unless one of these promotors finds a practical method to solve this
problem, and receives the Nobel Prize in physics, these air cars are
just a waste of bandwidth.

--
Mike

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