On Mon, 20 Jun 2005 14:22:04 +0000 (UTC),
wrote:

Discussion has drifted to using compressed air as energy-storage medium.

A company I used to work at processed wire, and powered the take-up
reel with a rotary-vane air-motor, used as a constant-torque drive.
Its air consumption was horrendous for the small amount of work it
did.

Another company used an old steam-powered fixed-crane to lift small
barges in and out of the water. Its boiler was long gone, so a 1000
CFM diesel air compressor powered it. Sometimes barely...

Are there available air motors efficient enough to make this storage
scheme practical?

Not that I know of. Like you I can think of examples that prove the
inefficiency - like a standard corded 3/8 drill that needs but a few
hundred Watts of electricity, while its air-powered cousin keeps a
1500 Watt compressor pretty busy. Just the same, I can imagine a
Bowjon type windmill/compressor generating compressed air for home
shop use. It wouldn't be efficient, but the losses wouldn't matter if
the shop's demands were low, and if the windmill, pump, tank and labor
were all cheap. It's not something I'd bother with though, and even
for somebody with lots of time on their hands, I'd expect wind-driven
shop air to come *after* solar-heated water and wind-powered battery
charging.

Wayne