Prospects for Flexible- and Bi-Fuel Light Duty Vehicles: Consumer Choice and Public Attitudes

Based on an analysis of several case studies of alternative fuel introductions [ethanol, biodiesel, liquefied petroleum gas (LPG), compressed natural gas (CNG)], requirements for alternative fuels, vehicles, and the fueling infrastructure are postulated that are necessary for successful market implementation. Affordable vehicle technology and costcompetitive fuel were identified as the most critical factors. Payback periods for additional vehicle costs associated with different alternative fuels are discussed. Fuel costs need to be consistently competitive in both the near-term and the longterm as demand for the fuel rises. For the vehicles, other considerations include backwardscompatibility or capability for two fuels, retrofit kits controlled by original equipment manufacturers (OEMs), and emissions compliance. For the fuel distribution infrastructure, affordable development and initially sufficient filling station numbers are required. For the fuel, important factors include energy density and adequate fill time, as well as the need for incentives and sufficient natural resource availability for sustainable fuels. For the long-term sustainability of an alternative future fuel, there should be a future source that is non-fossil (low CO2 emissions), renewable, and cost-competitive even when required in large volumes. Also considered are two possible future sustainable fuel scenarios involving ethanol and renewable methane. Ethanol in E85 can be used in today’s flex-fuel vehicles (FFVs) to overcome backwards compatibility limits of the existing fleet, allowing time for a compatible fleet to be deployed. Renewable methane (biomethane, e-methane) could be used at any blend level in today’s compressed natural gas vehicles (CNGVs). Near-term fuel flexibility from FFVs and bi-fuel or mono-fuel CNGVs is a key enabler for both scenarios.