Analysis of Underground Storage Tank System Materials with E15 Fuel

It is not the purpose of this report to define the acceptable limits of material performance or to rate individual materials. Rather, the purpose of this study was to assess critical property changes (volume, hardness, mass, etc.) for representative classes of materials used in underground storage tank systems with exposure to E15.

The Energy Independence and Security Act (EISA) of 2007 was an omnibus energy policy law designed to move the United States toward greater energy security and independence.1 A key provision of EISA modified the Renewable Fuel Standard (RFS) which requires the nation to increase the volume of renewable fuel blended into transportation fuels from 7.5 billion gallons by 2012 to 36 billion gallons by 2022. Ethanol is the most widely used renewable fuel, and increasing the ethanol content in gasoline to 15% offers a means of getting significantly closer to the 36 billion gallon goal. In March 2009, Growth Energy (a coalition of ethanol producers and supporters) requested a waiver from the United States Environmental Protection Agency (EPA) to allow the use of 15% ethanol in gasoline.2 In response the US EPA granted two partial waivers that allow (but do not require) E15 in 2001 and newer light-duty vehicles. Prior to the waiver being granted, uncertainties arose as to whether the additional fuel ethanol (from 10% to 15%), would cause an increase in leaking of underground storage tank (UST) systems, which include not only the tank but also the piping and connecting hardware.

The USEPA Office of Underground Storage Tanks was interested in determining how many (of the nearly 600 thousand) federally regulated underground storage tank (UST) systems across the U.S. could have releases or other failures if the ethanol content in gasoline increases from 10 volume percent to 15 volume percent. To better assess the leak potential, the EPA commissioned a study at Oak Ridge National Laboratory to develop a means to determine the potential of changes in releases and other failures if E15 fuel is stored in UST systems. Part of this effort was to develop an approach to estimate likelihood of failures and approaches for mitigating consequences associated with these failures. Currently, the lack of availability of data is the most significant barrier that prevents EPA from being able to perform the analysis.