ABSTRACT
The storage and transportation of biofuels continue to be of interest in a number of industries and countries. Depending on the type of biofuel, different materials compatibility issues arise. For the case of alcohol fuels, stress corrosion cracking of steels, and swelling and leaching of various polymeric materials are important. For biodiesels, uniform and localized corrosion of steels is important. This paper will provide an overview of research that has been conducted in alcohol fuels and identify gaps in knowledge.
INTRODUCTION
According to the U.S. Energy Information Administration, approximately 56 million m3 (14.8 billion gallons) of fuel grade ethanol (FGE) and 4.8 million m3 (1.26 billion gallons) of biodiesel were produced in the U.S. in 2015, the year in which whole-year data are available. In the U.S., more than 90% of the FGE is blended with gasoline, the most common being E-10 (10 volume percent ethanol blended in gasoline) that does not require engine modification. The use of the 95 volume percent ethanol (E-95) requires a flex-fuel engine. Originally, ethanol in the U.S. was used as an oxygenate addition to replace methyl tert butyl ether (MTBE), which is carcinogenic. However, after 2010, the Renewable Fuels Standard significantly increased ethanol consumption in the U.S. as a way to reduce greenhouse gas emissions. In contrast, Brazil has had a much longer history of ethanol usage of various concentrations in vehicles. The biodiesel is blended with petroleum diesel in different concentrations. B-20 (20 volume percent biodiesel in petroleum diesel) does not require engine modifications and is the most common blend used in vehicles. U.S. and Brazil dominate the world ethanol production; whereas, Europe dominates the world biodiesel production. Most of the ethanol used in the U.S. is produced from corn; whereas, that used in Brazil is essentially all from sugarcane. The high usage of ethanol and biodiesel requires a reliable infrastructure to store, blend, transport, and dispense the fuels. Additionally, leakage of biofuels can pose safety and environmental hazards. Therefore, materials compatibility, the subject of this review, is an important issue. In the case of biodiesel, corrosion is the most important concern for component integrity, whereas for ethanol stress corrosion cracking is the most important concern.
