RFA Says Ethanol is Not to Blame for Diesel Fuel Corrosion Incidents
by Kristy Moore (Renewable Fuels Association) Over the past 5 years, the RFA has been closely following the oil industry’s investigation into a recent rash of corrosion incidents in storage and handling equipment for Ultra Low Sulfur Diesel (ULSD) use. Under normal, everyday storage and handling conditions, ethanol should never come into contact with diesel fuel; ethanol is a gasoline additive. However, a report released today by Battelle, sponsored by the American Petroleum Institute (API), claims the recent diesel fuel corrosion incidents stem from ethanol contamination.
Battelle’s “Corrosion in Systems Storing and Dispersing Ultra Low Sulfur Diesel (ULSD), Hypotheses Investigation”, September 2012, concludes that since 2007, the rash of ULSD corrosion incidents stems from acetic acid, otherwise known as vinegar, from review of the 6 sites inspected. The report states that “Acetobacter” (the bacteria known to produce vinegar) has the capacity to produce the type of corrosion witnessed at the half a dozen locations.
…Sulfur in motor fuels provided the fuel with a natural type of lubrication and helped prevent bacterial growth. The phase-in period for EPA’s clean diesel program took place over a decade providing oil refiners with sufficient time to make the many changes to produce this low-sulfur diesel fuel.
Battelle’s report attempts to draw meaningful conclusions from surprisingly few data points which leave fuel experts with many questions. Quite frankly, there are numerous plausible scenarios that can cause severe and rapid corrosion, including the monumental shift away from diesel fuel containing high levels of sulfur that took place in 2006. Water contamination, humidity, ground water levels, incompatible UST equipment, nonfunctioning UST equipment, diesel fuel corrosivity, changes in chemical composition of diesel fuel, fuel additive over usage, diesel fuel additive under usage and microbial contamination are all equally important factors that should be investigated. The Battelle report acknowledges that “all of the sites inspected contained microbes,” the root cause of the corrosion, which leaves one questioning the presence of other environmental influences, especially when the site selected as the baseline or control was also found to have the vinegar-producing bacteria present.
…If ethanol contamination were indeed the root cause of equipment corrosion that started appearing in 2007, then an epidemic of corrosion incidents would have plagued the storage and handling sectors since 2002 when ethanol replaced ground water contaminating MTBE as the oxygenate of choice by oil refiners. EPA phased in ULSD in 2006; never before seen severe and rapid corrosion incidents became a nationwide concern in 2006. READ MORE