Traditional energy sources for the transportation sector continue to be depleted, causing concern for the future energy supply of the United States.  To provide additional short-term sources of fuels, energy providers are utilizing a variety of fuel blends such as the addition of ethanol to gasoline and biodiesel to diesel fuel.  As a solution over the long term, automobile manufacturers are developing an electric-drive hybrid vehicle platform to reduce emissions and increase overall fuel economy.  Of the options under consideration, the hydrogen fuel cell vehicle achieves the highest efficiency and environmental benefits.  Ultimately, hydrogen from renewable sources such as biomass, solar energy, and wind can maximize these gains while providing a pathway to a sustainable, independent energy supply.