In Kilmarnock, Scotland, bus passengers will soon be able to pay their fare with used cooking oil instead of cash. Eight buses carrying over 15,000 passengers a week will run on 100% biodiesel generated from used cooking oil and tallow, reducing carbon dioxide emissions by an anticipated 82% and virtually eliminating air-polluting sulfur emissions. As an added incentive to boost the program during its six month trial period, free containers will be provided to those who want to take their used cooking oil to a nearby recycling plant in exchange for discounted bus fare.

Biodiesel is one of the fastest growing alternative fuels in the world. However, most vehicles currently utilizing biodiesel rely on B20, a blend that is only one part biodiesel and four parts regular diesel. The emissions reductions from B20 are modest (less than 20% for carbon dioxide) and do not compare with other alternative fuel sources such as natural gas. And since most biodiesel is produced from virgin vegetable oil derived from crops such as soybeans and rapeseed, there are growing concerns that increased biodiesel generation will compete with food production and cause ecological harm.

Scotland’s innovative program eliminates many of these typical biodiesel concerns because its buses will run on 100% biodiesel (B100) derived entirely from recycled food industry by-products. A similar program exists in the United States, where the city of Berkeley, California runs its entire truck fleet on recycled cooking oil. In 2004, the New York Times reported that it would take only one-fifth of New York City’s waste cooking oil to fuel its entire public transit system. Back in the UK, even McDonalds is attempting to power its 155 delivery vehicles with its own restaurants’ oil waste by 2008.

Overall, the concept seems to hold a lot of potential for public and private transport systems around the world. Any existing diesel vehicle can utilize biodiesel, which is now available at many pump stations, with little to no engine modification. With a few small additions (fuel heaters and filters), diesel vehicles could even begin using waste cooking oil directly without refining, meaning that next time you go to a restaurant to fill your belly, you could fill your gas tank as well.

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