Exploring the potential of microbial biomass and microbial extracted oils in tribology: a sustainable frontier for environmentally acceptable lubricants

ABSTRACT

Mineral oil-derived lubricants, extracted from fossil fuels, account for approximately 90% of the lubricant market. A large proportion of these lubricants end up in the environment through usage, spillage, and disposal, leading to contamination of aquatic systems, ecosystems, and agricultural lands. To address this, new regulations were released (e.g. Vessel General Permit 2013) to promote the use of Environmentally Acceptable Lubricants (EALs) over conventional, toxic, non-biodegradable mineral oils. Today, the range of EAL is limited, particularly affecting the maritime sector. Since 2013, the variety and effectiveness of EALs have improved, but further advancements and cost reductions are essential. This study focuses on developing sustainable bio-based additives from microbial processes to enhance EALs. These additives, sourced through fermentation, avoid using fossil fuels and do not require arable land, preserving water resources and food production areas. The research reveals that yeast, high in sulfur and phosphorus, and microbial oils, mainly carboxylic acids, effectively stabilize EAL formulations, reducing friction and wear in water-based lubricants. Microbial oils are superior in reducing friction, while yeast offers better wear protection. This study opens the possibility of incorporating various bio-based products into EALs, providing a sustainable, environmentally friendly option.

GRAPHICAL ABSTRACT

KEYWORDS:

• Environmentally acceptable lubricants
• microbial biomass
• lubricant additives
• Saccharomyces cerevisiae
• oleaginous yeast

Acknowledgements

Authors acknowledge: Novozymes A/S (Bagsværd, Denmark) for kindly providing the enzyme Cellic CTec3; biorefinery Borregaard (Sarpsborg, Norway) for kindly providing the Excello-90 hydrolysate and the BALI pulp; Fibenol OÜ for providing the C5 hydrolysate.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

All data generated or analysed during this study are included in this published article and its supplementary materials files.

Authors’ contributions

Conceived the research idea: S.A.; S.B.; F.D.B. Designed the experiments: S.A.; S.B.; E.V.; F.D.B. Methodology: S.A.; S.B.; E.V.; F.D.B. Performed the experiment: S.A.; S.B.; E.V.; F.D.B.; D.K, N.B, T.H. Discussed the results: S.A.; S.B.; E.V.; F.D.B.; N.B; A.K.K.; P.S.; M.V.; L.Z. Analyzed the data: S.A.; S.B.; E.V.; F.D.B.; T.H.; A.K.K.; P.S.; M.V.; L.Z. Wrote the manuscript: S.A.; S.B.; E.V.; F.D.B. Discussed and revised the manuscript: S.A.; S.B.; E.V.; F.D.B.; P.S.; All authors read and approved the final manuscript.

Additional information

Funding

The study was funded by EEA Grant. Novel Routes for cost effective Environmentally Acceptable Lubricants. Project Number:CZ-RESEARCH-0014. Norwegian Research Council FME - Centre for Environment-friendly Energy Research Bio4Fuel. Project Number:257622.