• Hydrogen comprises more than 75 percent of the environment, but it primarily occurs in association with other elements, the Army Logistics University points out. In its pure or free state, hydrogen is a useful fuel, with considerable advantages over petroleum-based fuels--it is renewable and non-polluting, is the most abundant element on earth and it has higher energy density. Hydrogen as a primary fuel would eliminate dependence on foreign sources of fuel.
  
  

Pollution Free

• Hydrogen combustion produces only water as a byproduct. Hydrogen generates energy without releasing greenhouse gasses or pollutant particles, according to the Hydrogen Energy Center. Water is the only byproduct because hydrogen, for being in its pure state, does not contain any carbon molecules, which are associated to the production of carbon monoxide during fossil-fuel combustion, reports space scientist Dr. Mark Looper Ph.D. in the website Uncle Mark's Alternative Fueling Station.
  
  

Renewable and Abundant

• Hydrogen gas can be produced from methane, gasoline, biomass, coal or water, but each one of these sources bring very different amounts of pollution, according to the Hydrogen Energy Center. The only pollution-free source of hydrogen is water, which is also the most abundant. A simple process called electrolysis can liberate hydrogen from water. Renewable sources of energy, such as the wind and sun light, can be used to power the equipment, called electrolyzers.
  
  

High Energy Density

• Hydrogen has a higher energy density than petroleum-based fuels, meaning it supplies more energy per volume than gasoline, diesel or kerosene, according to the Army Logistics University. Hydrogen is the lightest naturally occurring element, and it contains high-energy chemical bonds. Hydrogen generates twice as much energy as natural gas, and almost three times more when compared to gasoline.