21.   Fuel cells use hydrogen, extracted from fuels such as gasoline and diesel, to generate electricity to power a vehicle.

22.   Ideally, compressed hydrogen would be used as a fuel because it would not create any harmful tailpipe emissions.

23.   If pure hydrogen is used as a fuel, the only emission is water vapor.

24.   Hydrogen can be produced from natural gas aboard vehicles or pure hydrogen can be used, requiring development of a new supply infrastructure.

25.   Pollution-free fuel cells, which use hydrogen to create electricity, have become the center of auto industry research.

26.   The only tailpipe emissions from fuel cell vehicles that use pure hydrogen is water vapor.

27.   The only way carbon dioxide production is completely avoided is if hydrogen is used as the fuel.

28.   They said many balloon companies were using hydrogen because helium was five times more expensive, according to the Post.

29.   When pure hydrogen is used the only tailpipe emission is harmless water vapor.

30.   When pure hydrogen is used, the only byproduct is water vapor.