A Southern Georgia school district is considering ordering 53 propane-fuelled school buses. "They're healthier, they're cleaner burning, and they're much quieter than the diesel option," said a school administrator. Propane-powered buses also reduce greenhouse gasses by 22% compared to gasoline- powered buses and 6% compared to diesel ones. But they come at a premium$103 000 for a propane model, $15 000 more than the diesel equivalent. The propane bus operating cost (above and beyond fuel cost) is 30 cents/kilometre, compared to 40 cents for the diesel. Diesel fuel costs about $2/litre in Georgia, about $1 more than propane. Bus mileage is 12 kpl for the propane model vs. 10 kpl for diesel. The life of a school bus in the district averages nine years, and each bus travels an average of 30 000 kilometres per year because the district is so large and rural. Which bus is the better choice based on a life cycle analysis