Issues for storing plant-based alternative fuels in marine environments

Area of Science:

• Marine corrosion science
• Microbial biodegradation
• Fuel storage

Background:

• Marine environments present unique challenges for fuel storage due to interactions between fuel, seawater, and materials.
• Biodegradation of fuels by marine microorganisms can influence corrosion processes.
• Understanding these interactions is crucial for preventing material degradation and ensuring fuel integrity.

Purpose of the Study:

• To evaluate biodegradation and corrosion of carbon steel in coastal seawaters exposed to alternative and conventional fuels.
• To investigate the role of oxygen and microbial activity on corrosion mechanisms at the fuel/seawater interface.

Main Methods:

• Exposure of uncoated carbon steel at the fuel/seawater interface in two distinct coastal seawaters (oligotrophic and eutrophic).
• Monitoring of polarization resistance to assess corrosion rates.
• Analysis of corrosion products for sulfides and chlorides, and detection of metabolites like catechols.

Main Results:

• Oxygen depletion (<0.1 ppm) occurred within 2 days due to corrosion and aerobic microbial respiration.
• Sulfides from anaerobic sulfate-reducing bacteria and chlorides were found in corrosion products.
• Persistent catechols indicated aerobic biodegradation, suggesting initial oxygen exposure led to metabolites that exacerbated corrosion.

Conclusions:

• Initial transient oxygen exposure promotes aerobic biodegradation, forming metabolites that intensify subsequent carbon steel corrosion.
• Microbial activity, both aerobic and anaerobic, plays a significant role in fuel-seawater-metal interactions and corrosion.
• These findings highlight the complex interplay between fuel type, marine environment, and material degradation.