Battelle Study Sheds Light on UST Tank Corrosion

Battelle recently released a study regarding corrosion in diesel Underground Storage Tanks (USTs). The report "Corrosion in Systems Storing and Dispensing Ultra Low Sulfur Diesel (ULSD), Hypotheses Investigation," links ethanol to corrosion in USTs, even though ethanol isn't a component of diesel. The report suggests ethanol is finding its way into ULSD tanks through fuel equipment shared with ethanol-blended gasoline. The report concludes that corrosion is likely being caused by acetic acid produced by Acetobacter bacteria, which feeds on low levels of ethanol present as a contaminant in ULSD tank systems. In the presence of water, the bacteria ferments the ethanol and forms acetic acid. Corrosion associated with ethanol is suspected to be worse with smaller amounts of ethanol than with fuels blended with 10 percent ethanol or higher. Fuels with higher ethanol concentrations draw excess water from condensation into the fuel, reducing corrosion risk.