The entire world, with its dependence upon, and sharp competition to secure, fossil fuel energy sources, is coming to a crisis that may be unmatched in its history. Serious questions are raised about whether the world can maintain a population that it is already straining to provide for unless it has the availability of cheap petroleum fuel to drive nations' economies. Complicating this is the unquestionable negative impact that fossil fuel use has on the environment, which threatens the well being of the population that it is needed to support.
It is clear to even the most casual observers that a change away from fossil fuels to clean, non-polluting renewable fuels is required, and several forms are available. There is no single source of these fuels that can be provided in adequate amounts to satisfy a huge and growing demand, but a mix of these technologies can fill the bill.
Let's begin with an inventory of the technologies that are most frequently touted in the popular media.
Fuels from plant materials, like ethanol and methanol, are an easy option to replace some petroleum used in powering internal combustion engines. The attraction of this option rests exclusively in its being a renewable option, since more biomass can be grown to provide refinery feed stocks. It also enjoys strong political support in states with large agricultural industries. However, it does have its disadvantages.