Its my understanding that the hydrogen can be manufacured as it is used
By using a catalyst to convert methanol, ethanol, natural gas, propane, butane, etc... into carbon (pollutant) O2 and H.
Or the hydrogen could be manufactured at the gas station itself...So that the pollution would be contained. (Probably possible to use common automotive fuels or natural gas to do this.)
Be creative! Develop a solution! Patent it! You'll be the rich guy I know from the internet.
Scott (Please just remember me in you charitable giving)