By Keith Turner

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t1">There’s little question that the world is running thin on fossil fuels. If not now, then in the future, we will be overextending our use of oil, coal and natural gas.

t1">That’s why automakers are scrambling to research and introduce new fuels, or combinations of fuels, to power our next vehicles. Michael Coates of HybridCars.com explains a couple possibilities:

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t1">• Clean Diesels – This term is used in reference to the new diesel vehicles coming on the market, mainly to differentiate them from the last generation of diesels, which were not so clean.

t1">Cleaning diesel fuel has been a three-step process. First, the diesel fuel was cleaned up in 2006 when the sulfur was taken out and ultra low sulfur diesel was introduced. Automakers started building engines designed to run on this new fuel and tuning them to meet the most stringent emissions regulations.

t1">To meet the regulations, an after-treatment is typically needed in the form of a filter and some kind of nitrous oxide reduction treatment. The low-sulfur diesel is critical to keep the after-treatment equipment running correctly, since sulfur will clog filters.

t1">The first clean-diesel vehicles go on sale late in 2008. The Volkswagen Jetta and Jetta Sportwagen will offer turbo diesels; Mercedes has just added three clean-diesel SUVs; and BMW’s 3-series and X5 will debut by the end of 2008, followed by the Audi Q7 and A4, Acura TSX and possibly others, including some light-duty pickup trucks. Virtually all automakers are planning to introduce clean diesels in the next couple of years.

t1">BlueTec is Mercedes’ trade name for its clean-diesel system. It indicates a suite of technologies used to make their diesels as clean as their gasoline engines.

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t1">• Biofuels – Biofuels are made from non-petroleum sources. Biodiesel and ethanol are the two main biofuels in use now. In the United States, biodiesel is usually made from soybeans, while ethanol is typically made from corn. They are considered first-generation biofuels.

t1">Second-generation biofuels typically come from non-food sources, such as biomass, waste and cellulosic products, and are often created with a process that results in a higher-quality fuel that is more comparable to and more easily blended with a petroleum fuel.