[Christ]

More than likely near impossible. There are surely more than 22CFM of air flowing in the exhaust for direct capture, but again, at what pressure? You'd choke the engine out trying to power the tool directly, I fear.

However, if the system were closed loop, never allowed to actually become steam, water is ~800 times more dense than air of a similar temperature, right?

22/800= .0275CFM of heated water flow.

That might not be correct, and I'm sure someone else knows how it should really be, but maybe it's at least encouraging?

What I'm suggesting is that pressurized water will take FAR less volume to produce the same power for a given pressure.

If you figure that your tool takes 22CFM at 90PSI, it *should* only take less than .25CFM of water at the same pressure. That means you can lower the pressure significantly while upping the flow rate, and you'll achieve the same end.

So, if you can't get the pressure up to the 90PSI that most air tools require for max load/power, you could just flow more volume at a lower pressure, like 1CFM of water at 60PSI or 2CFM of water at 30 PSI (not accurate figures, etc.)

Also, since you mention that your grinder felt lacking in power -

1. It wasn't meant to be strong, by any means, so no news there.
2. The power curve of air-powered tools is not even close to linear. It spikes somewhere in the chart, and that's about where it's most efficiently run for the power/air pressure/volume charade.