Jem Stansfield's AirPed.

"A former sheepherder and current rocket scientist/inventor Jem Stansfield, took a couple of air canisters that are typically used by firefighters for their breathing gear, and strapped them on a moped. The result is an air-powered bike that spits out cleaner exhaust then the air that it initially takes in.

Both compressed air cylinders drive a pair of rotary air engines that propel the bike to a top speed of 18mph. It will only go about 7 miles until more air is required. Lucky for him, he has a local dive shop where he can fill up and he’s good to go."