The TV presenter Jem Stansfield modified this small moped to function on compressed air stored in two high pressure carbon fiber tanks, like the ones that the firefighters use. The engine has been replaced by two rotary air engines. The two tanks can be fully charged in a matter of seconds from any air compressor. This compressed air bike can go about 8 miles, reach a speed of 18mph (about 30km/h).
The inventor says he could never travel big distances with it, but it surely is clean. Now if the compressor had a clean power source, that would be to the benefit of the environment, since I can imagine compressing the air is much more efficient and cleaner than burning the fuel locally in the motorbike’s engine.