Milestone Report: Technical Barriers to the Use of Ethanol in Diesel Fuel

Ethanol-diesel blends (or e-diesel) contain up to 15 volume percent ethanol and an additive known as an emulsifier. The fuel mixture is known as a micro-emulsion and is prepared by splash blending, a process that requires no special equipment or temperature control. Ethanol-diesel blends have a number of potential advantages including: (1) Displacement of imported petroleum with a domestic and renewable resource; (2) Significant lowering of diesel particulate matter emissions; (3) Possible improvement in cold flow properties imparted by the ethanol; and (4) Possible improvement in fuel lubricity imparted by the emulsifier additives. The objectives of this study are a) to examine the status of ethanol-diesel blends and b) to identify barriers and technical gaps that hinder rapid introduction of these fuels into the market. The results of this assessment and planning process will allow the Department of Energy (DOE) to understand the issues facing the industry and to determine if and how DOE involvement might assist in overcoming the identified technical barriers. This document includes a brief description of ethanol production, distribution, and storage as background information. This is followed by a description of ethanol-diesel blends (e-diesel) and the properties of these fuels. Engine performance and regulatory requirements are also described. Potential technical barriers are noted in each of these areas and summarized at the end.