A COMPARATIVE COST-ANALYSIS OF BIODIESEL, COMPRESSED NATURAL-GAS, METHANOL, AND DIESEL FOR TRANSIT BUS SYSTEMS

A comparison of operating costs for buses used in a transit system are investigated considering four alternative fuels: biodiesel, compresse d natural gas, methanol, and diesel. Rust's 'nested fixed point' maxim um likelihood estimation algorithm is used in this comparison. The alg orithm considers both tangible costs such as fuel, maintenance, and in frastructure, and intangible costs associated with different levels of bus engine operating reliability under alternative fuels. Using data on actual monthly mileage and time of engine rebuilds under the four a lternative fuels, the Rust algorithm is employed assuming that an opti mal maintenance strategy is adopted for each alternative fuel type. Re sults indicate that although biodiesel and biodiesel blends have highe r total costs than diesel fuel, they have the potential of competing w ith CNG and methanol as fuels for urban transit buses. (C) 1997 Elsevi er Science B.V.