Oldendorff and MIT Find Fuel Degradation in Study of Advanced Biofuel
With an increasing exploration of biofuel across many sectors of the shipping industry and the emergence of new second-generation advanced biofuels, Oldendorff Carriers, one of the world’s leading dry bulk owners and operators, commissioned a study looking at the stability and potential for degradation of biofuel. Working with the Massachusetts Institute of Technology (MIT) they launched a study of the long-term stability of advanced biofuel (B20 blend) as a follow-on to a previous study of using biofuels to reduce emissions. They are now reporting that exposure to air, water, and light contributed significantly to fuel degradation in the advanced blends.
Results of the study were presented yesterday, November 6, at the American Institute of Chemical Engineers Annual Meeting. Oldendorff highlights in its summary of the results concerns identified regarding microbial contamination and oxidative degradation. The study looked at the fuels over a one-year timeframe and highlights steps to be taken as the use of the fuel expands to address the degradation as well as positive issues such as no sediment formation or water increase over time.
Oldendorff highlights that a biofuel blend is more complex than a homogenous product. Specifically, they point out as the industry moves to second-generation products that the presence of unsaturated fatty acids, which are inherent in the vegetable oils and animal fats from which the new biofuel is derived, is more prone to oxidative degradation. The concern is the potential for degradation of biofuel blends with conventional marine fuels over time when stored in vessels’ bunker tanks.
“There is a limited body of research on the degradation of biofuel blends, with existing studies primarily focusing on first-generation biofuels (derived from food crops) and/or distillate biofuel blends rather than advanced residual biofuel blends,” comments Oldendorff. The study with MIT sought to address this lack of information by monitoring eight chemical parameters over an extended period of time, under a variety of storage conditions and temperatures.
The Edwine Oldendorff was used for the study, a 38,600 dwt bulker built in 2016. The vessel was fueled in January 2022 with an advanced B20 biofuel, consisting of 20 percent bio-oil derived from used cooking oil and blended with very low sulfur fuel. Three storage groups were set up for the study using different containers and temperatures. The selected storage conditions closely replicate typical onboard fuel storage conditions and investigate the impact of storage temperature, air, light, and water on the fuel quality over time.
The findings show that fuel degradation was observed with levels of microbial contamination increasing over time. Emerging after the first month, the highest levels of contamination increased over time in samples exposed to light. Warning that microbial contamination could lead to operational problems, including fouling of tanks, pipes, and filters, tank corrosion, and fuel injection equipment damage, the report highly recommends a biocide addition to preserve blended biofuel for an extended period.
Similarly, oxidative degradation was observed starting between three and six months, with the report concluding that the addition of antioxidants is recommended. They are also calling for regular monitoring of fuel quality for long-term onboard storage, especially with higher biofuel blends. However, the study did not find sediment was generated after thermal aging, but says that the impact of storage temperature on degradation remains unclear.
“The results of our study will be valuable for both biofuel producers and users, assisting them in planning their bunker storage and maintenance systems accordingly over time,” concludes the team from MIT and Oldendorff.