I hate when people make claims like this. It's not powered by air. Most likely it's powered by a fossil fuel - just like everything else.
Compressed air is just energy storage. Terribly inefficiency energy storage at that. I don't know who filled his scuba tank, but I'm guessing they did it with a compressor that either runs on gasoline or deisel or it plugs into the wall where it gets electricity from a coal powered station.
it's not without it's advantages though. Compressed air fills much quicker than you can charge a battery. So that's something. I don't know if there's any weight savings as i suspect a tank capable of holding 4000 psi is going to weigh as much as a comparable lithium battery.