12NOV2019 - NEWS - Could bugs in biofuel eat into your engine?

Shipowners looking to comply with the IMO 2020 sulfur cap by using fuels with biofuel blended in may face an unexpected problem: increased risk of microbial influenced corrosion (MIC)

Fredericton, New Brunswick, Canada headquartered microbial monitoring specialist, LuminUltra has important concerns over the quality of some IMO 2020 compliant fuels as shipowners blend biodiesel with HSFO and distillates to reduce SOx emissions.

LESS SULFUR, MORE BUGS
“The addition of biodiesel will reduce the sulfur content, but ship operators do need to be aware this can result in increased microbial influenced corrosion (MIC),” says Patrick Taylor, LuminUltra’s Director of Global Business Development. “Less sulfur means more bugs.”

Taylor says that the high sulfur content of residual fuel has been an “excellent inhibitor,” preventing the build-up of microbial growth and, consequently, the microbial induced corrosion of fuel tanks and systems.

“There is an increased biodiesel content in Marine Gas Oil (MGO) and we are seeing HSFO now being blended with recovered distillates to reduce the sulfur level,” he notes.” As biodiesel has a high water content, these new fuels can be nutrient-rich breeding grounds for microbiological growth. There are real risks, real safety concerns.

Microbes associated with MIC tend to fall into two camps: aerobic, where microbes require oxygen, and those that don’t, anaerobic. Water is the elixir of life for both these types, with microbes requiring little to form colonies and expand.
Although there is still a lack of information on water absorbance in biodiesel/diesel blends, research has shown that at constant relative humidity, biodiesel absorbed 6.5 times more moisture than diesel.