Lawyer, K., Ickes, A., Wallner, T., Ertl, D. et al., "Blend Ratio Optimization of Fuels Containing Gasoline Blendstock, Ethanol, and Higher Alcohols (C3-C6): Part I - Methodology and Scenario Definition," SAE Technical Paper 2013-01-1144, 2013, doi:10.4271/2013-01-1144.
The U.S. Renewable Fuel Standard (RFS2) requires an increase in the use of advanced biofuels up to 36 billion gallons by 2022. Longer chain alcohols, in addition to cellulosic ethanol and synthetic biofuels, could be used to meet this demand while adhering to the RFS2 corn-based ethanol limitation. Higher carbon number alcohols can be utilized to improve the energy content, knock resistance, and/or petroleum displacement of gasoline-alcohol blends compared to traditional ethanol blends such as E10 while maintaining desired and regulated fuel properties.Part I of this paper focuses on the development of scenarios by which to compare higher alcohol fuel blends to traditional ethanol blends. It also details the implementation of fuel property prediction methods adapted from literature. Possible combinations of eight alcohols mixed with a gasoline blendstock were calculated and the properties of the theoretical fuel blends were predicted.Each scenario details an overall objective and identifies chemical and engine related properties that are crucial to meeting that objective as fuel criteria. Appropriate target values for each criterion are based on U.S. fuel industry standards, consumer expectations, engine requirements, and government legislation.The objective of the E10/E15 Alternate scenario is to identify alcohol blends with oxygen content that meet the EPA E15 waiver, have vapor pressure within ASTM standards, and energy content, knock resistance, and petroleum displacement at least equal to that of current ethanol blends. The objective of the RFS2 Fuel scenario is to identify blends that contain an ethanol-equivalent alcohol volume that meets the RFS2 requirement in addition to vapor pressure, knock resistance, and energy content criteria similar to those in the E10/E15 Alternate scenario.