Biofuels are becoming more and more common in the petroleum industry, as both consumers and regulators increasingly demand more efficient and more environmentally-friendly products. Biofuels such as ethanol are more efficient and burn cleaner than traditional fuels. Ethanol is now commonly found in gas stations blended with gasoline to produce E85, E87, and E10 blends.
As demand for biofuels increases, owners of facilities that need to store them are raising a number of questions concerning the safe storage of biofuels. One of them, which we’ll address in this blog, is whether biofuels are compatible with steel storage tanks.
Biofuels and Steel Storage Tanks
No research has shown biofuels to be incompatible with steel storage tanks, according to the Steel Tank Institute. In its Statement of Compatibility, the STI states that “all makes and models of steel tanks manufactured in any time period…are suitable for use with all blends of fuels meeting ASTM standards.” This includes:
The STI also recommends that steel tank owners use components in steel storage tank systems that have either been listed by a nationally-recognized independent testing agency, or have been “approved by the manufacturer to be compatible with the fuel stored.”
What are the risks associated with the storage of biofuels?
A not insignificant number of storage tank owners have found that biofuels have caused corrosion in their tanks and/or tank equipment and components. The reason for this is not due to the composition of the tank and equipment, but rather the nature of how biofuels interact with the environment.
“Newer fuels with high ethanol concentrations absorb more water from their environment,” according to STI. “As fuel absorbs water, layers can form in the stored fuel.” This phenomenon also occurs in Ultra Low Sulfur Diesel (ULSD).
So, what’s causing the corrosion is not the fuel, but the water it draws in from the environment. Water allows microbes to grow in the tank and its components, and these microbes eat the organic components of the biofuel. They produce acids as a byproduct, which in turn can degrade the tank and equipment.
Proper Maintenance of Biofuel Storage Tanks is Critical
Because of this phenomenon, proper maintenance of biofuel storage tanks is critical in preventing corrosion.