The big knocks against petroleum-based fuels including gasoline and diesel are that one day they’ll run out, and in the meantime, they are literally choking the planet with their emissions.
On the other hand, these liquid-based fuels have a high energy density -- they pack a mighty kick in a small amount of volume compared to other known fuel sources. One happy medium for many fleets is the use of non-petroleum, renewable fuels such as biodiesel. Derived from soybeans, algae, or even used cooking oil, biodiesel provides nearly the same power output as petroleum-based diesel, but with substantially lower emissions.
It can be blended with regular diesel in varying concentrations (B100 is 100-percent biodiesel) and is generally safe for diesel engines as long as the fuel is of high quality. It’s even been said that the fat concentrations in biodiesel provide helpful lubrication to engine parts. Once a novelty, today you can find biodiesel at many filling stations alongside the pumps for regular unleaded. Some companies, including McDonald's and Wal-Mart, even recycle their stores’ own cooking oil for use as fleet fuels.
Biodiesel does come with some caveats, however. It reacts badly with PVC and certain other plastics, as well as parts made from natural rubber (found mostly on older cars). Then there’s the debate over whether fertile farmland should be used to grow crops for vehicle fuel or for food.
In any case, many policy makers see biodiesel and other homegrown liquid fuels such as ethanol as not only bulwarks against climate change, but also as steps along the path of weaning the United States from its dependence on foreign oil.
Conventional fuels can’t help but spew carbon dioxide and soot particles into the environment -- it’s in their chemical composition. But one technology drastically cuts emissions by making regular-fuel vehicles super efficient. Learn how it’s done on the next page.