A Southern Georgia school district is considering ordering 56 propane-fueled 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 23 % compared to gasoline-powered buses and 55 % compared to diesel ones. But they come at a premium, $94,000 for a propane model, $13,000 more than the diesel equivalent. The propane bus operating cost (above and beyond fuel cost) is 38 cents/mile, compared to 47 cents for the diesel. Diesel fuel costs about $22 /gallon in Georgia, about $1 more than propane. Bus mileage is 99 mpg for the propane model vs. 77 mpg for diesel. The life of a school bus in the district averages 10 years, and each bus travels an average of 25,000 miles per year because the district is so large and rural.
Which bus is the better choice based on a life-cycle analysis? The total cost of using one propane-fueled bus during its life cycle is $ nothing.
a. The total cost of using 1 propane-fueled bus during its life cycle is $ ___
b. The total cost of using one diesel-fueled bus during its life cycle is $ ____
c. The propane-fueled bus or diesel-fueled bus is the better choice based on a life-cycle analysis?