Issues for storing plant-based alternative fuels in marine environments

Anaerobic Biodegradation of Alternative Fuels and Associated Biocorrosion of Carbon Steel in Marine Environments

“…Profilometry is a powerful and versatile tool to evaluate pitting corrosion. ,,,, Quantitative analysis using this technique indicated that the severity of pitting also correlated well with sulfate loss (Figure B). Since the carbon steel coupons in some SDB incubations were completely penetrated (Figure ), the maximum pitting depth (>1000 μm) was much more pronounced than those (<100 μm) reported in previous studies under transient oxygen conditions. , Regardless of the mechanism, the severity of pitting corrosion is also largely (69%) associated with biogenic sulfide production in anaerobic fuel-degrading systems. Collectively, these findings suggest that the synergistic effects associated with corrosive sulfide formation, acidic metabolic production (e.g., organic acids), and biofilm formation accelerate both the general and pitting corrosion process on carbon steel surfaces. ,, Since the highest sulfate depletion rates were always associated with camelina-JP5, it can be reasonably speculated that such hydroprocessed biofuels might present more risk due to accelerated pitting corrosion under normal marine conditions relative to other fuels.…”

“…In this study, we evaluated two advanced biofuels (FT-F76 and camelina-JP5) and their conventional petroleum counterparts (F76 and JP5) which are primary fuels used by the US military . These biofuels may be exposed to transient oxygen levels in the seawater-compensated fuel ballast tanks that are onboard many naval vessels. , Several studies have suggested that aerobic microorganisms might initiate the biodegradation of hydrocarbons to provide partially oxygenated chemical constituents to support the growth of SRBs. ,, It was also postulated that SRB would degrade fuel hydrocarbons directly when anaerobic conditions prevailed in the ballast systems. , Such presumptions were supported by the detection of hydrocarbon-degrading SRB and associated genes (alkylsuccinate synthase, assA ) in naval ballast tank waters . Due to the limited opportunity to obtain seawater-compensated fuel ballast tank samples, coastal seawaters used to initially fill such tanks were used as inocula in our experiments.…”

“…Therefore, the US Navy is now considering alternative biofuels, , mainly including hydroprocessed camelina-JP5 and Fischer–Tropsch (FT) diesel fuel FT-F76 from renewable sources . Typically, these renewable fuels are used experimentally as 50/50 blends with petroleum fuel in tactical vehicles. , Previous studies have shown that the molecular-weight range of hydrocarbons in naval biofuels is narrower than that in traditional petroleum fuels. , Moreover, FT fuels contain more branched alkanes and fewer aromatic compounds compared to petroleum fuels . Recent studies have shown that FAME biodiesel and hydroprocessed biofuels (camelina-JP5 and algae-F76) are amenable to biodegradation under transient oxygen conditions and can accelerate carbon steel corrosion. ,, The black corrosion products deposited on coupons were mostly mineral sulfides, suggesting that the majority of metal damage occurred when anaerobic conditions prevailed.…”

Understanding marine biocorrosion: experiments with artificial and natural seawater

“…Aktas et al . ( 2010; and Lee et al . ( 2014 ) demonstrated another important consequence of using gas mixtures to remove oxygen.…”

“…However, Lee et al . ( 2010a;2014 ) subsequently demonstrated that addition of readily biodegradable fatty acid methyl ester biodiesel to both anaerobically maintained KW and PG seawaters still resulted in higher corrosivity and sulphide production in KW. Aktas et al .…”