What are the differences between hydrogen and other fuels?
Hydrogen can be produced from a fuel such as ethanol, gasoline, natural gas, methanol, or through the electrolysis of water. Carbon based fuels are harvested from limited, naturally occurring, underground reserves. Hydrogen contains about 2.6 times the energy per unit mass as gasoline (i.e.: 1 kg of hydrogen has 2.6 times more energy than 1 kg of gasoline). However, hydrogen needs about 4 times the volume for a given amount of energy (i.e.: it takes 4 gallons of hydrogen to have the same amount of energy as is contained in 1 gallon of gasoline). Hydrogen readily disperses upwards, whereas gasoline is a liquid and therefore pools on the ground. The burning of carbon based fuels emits carbon dioxide, carbon monoxide, oxides of nitrogen, hydrocarbons, particulate matter and other potentially toxic compounds. Whereas combusting hydrogen produces heat, water, and some oxides of nitrogen. In hydrogen fueled, fuel cell engines, only heat and water vapor are produced.
