Ethanol. Available at fuel pumps throughout the Upper Midwest for the better part of 30 years, this widely available gasoline is also known as E10 (90 percent regular unleaded gasoline, 10 percent corn-based ethanol). Starting the 1990’s, E85 (15 percent regular unleaded gasoline, 85 percent corn-based ethanol) also started to become available at the retail level. Advantages of both blends included the renewable corn feedstock, a lower combustible temperature, lower tailpipe emissions, higher fuel octane and best of all, a lower price. However, because the blends have a lower energy density than regular unleaded gasoline, fuel economy is slightly lower.
Several events came together during the middle of the last decade to increase the use and production of ethanol blends. First, The Energy Policy Act of 2005 required a target of renewable fuel use in the United States by 2012 and then the Energy Independence and Security Act of 2007 further raised the standard to a higher minimum level of annual renewable fuel use by 2022. A large portion of this fuel had to be advanced biofuels, defined as renewable fuels that reduce greenhouse gases by at least 50 percent. Second was the discovery that MTBE (methyl tertiary butyl ether), was responsible for polluting groundwater near locations where regular gasoline containing the additive was stored. Most states had banned its use in gasoline by 2005.
Ethanol was touted as the perfect replacement. MTBE was one of a group of chemicals commonly known as oxygenates because they raise the oxygen content of gasoline. MBTE had been used in gasoline at low levels since 1979 to replace tetraethyl lead and to increase its octane rating helping prevent engine knocking.
Oxygenates like MBTE help gasoline burn more completely, reducing tailpipe emissions from pre-1984 motor vehicles; dilutes or displaces gasoline components such as aromatics (e.g., benzene) and sulfur; and optimizes the oxidation during combustion. Most refiners chose MTBE over other oxygenates primarily for its blending characteristics and low cost. It is its blending characteristics that eventually did the addictive in.
Ethanol: The Truth – There has been a lot of misinformation about ethanol blends since they started to be come more widely available. Fuel system problems, hard or no start conditions, rough idle and a whole variety of ills have been communicated in various places over the years. What you DON’T know: A section of The Energy Independence and Security Act of 2007 directed the DOE (Department of Energy) to assess the feasibility of using intermediate ethanol blends in the existing vehicle fleet. Evaluated by the National Renewable Energy Laboratory (NREL) and in a preliminary 2008 report, the NREL described the effects of E10, E15 and even E20 on tailpipe and evaporative emissions, catalyst and engine durability, vehicle driveability, engine operability, and vehicle and engine materials.
This report found that none of the vehicles displayed a malfunction indicator light, no fuel filter plugging symptoms were observed, and no cold start problems were observed under laboratory conditions.