Hydrogen Sulfide - It's Not Only About Sulfate

As the energy sector increasingly relies on gas and hydrogen storage to meet demand and support renewable energy integration, understanding the microbiological dynamics within these storage systems is vital. Among the various microbial players, sulfate-reducing bacteria (SRB) and sulfate-reducing archaea (SRA) hold significant importance. These microorganisms, which metabolize sulfur compounds to toxic hydrogen sulfide (H2S) can challenge and storage operations.

Pitting corrosion of pipeline.

Pitting corrosion and oxygen

Understanding Sulfate-Reducing Microorganisms

SRB and SRA are anaerobic microorganisms that thrive in oxygen-free environments commonly found in subsurface storage systems. These microbes utilize sulfur compounds such as sulfate, thiosulfate, sulfite, and elemental sulfur as electron acceptors during their metabolic processes, producing H2S as a byproduct. This characteristic can impact gas and hydrogen storage in several ways:

1. Sour Gas: The presence of H2S results in "sour gas," a term used to describe natural gas containing significant amounts of hydrogen sulfide, which can require extensive purification processes.

2. Corrosion: The production of H2S can lead to microbiologically influenced corrosion (MIC) of storage infrastructure, compromising the integrity of pipelines, tanks, and other equipment.

3. Gas Quality: Hydrogen sulfide is a toxic and corrosive gas that can contaminate stored gases, affecting their quality and necessitating costly purification processes.

4. Safety Risks: The accumulation of H2S poses significant safety risks due to its toxicity and potential to cause structural failures in storage facilities.

Sulfur Compounds and Microbial Growth

Sulfate-reducing microorganisms do not limit their activity to sulfate alone. They also utilize other sulfur compounds such as thiosulfate, sulfite, and elemental sulfur. Additionally, technical substances injected into storage systems, such as certain corrosion inhibitors and chemical additives, can inadvertently provide substrates that enhance microbial growth. Understanding these interactions is crucial for effective management of storage facilities.

1. Thiosulfate and Sulfite: Both compounds can serve as alternative electron acceptors for SRB and SRA, sustaining their growth and H2S production even when sulfate levels are low.

2. Elemental Sulfur: Often present in natural gas and hydrogen storage environments, elemental sulfur can be metabolized by SRB and SRA, contributing to corrosion and contamination issues.

3. Technical Substances: Chemical additives used to maintain storage integrity can sometimes contain components that unintentionally support the proliferation of these microorganisms, exacerbating H2S-related problems.

The sulfate-reducing bacterium Desulfomicrobium aggregans in a biofilm with the methanogen Methanobacterium cahuitense (Dengler et al, 2023).

Monitoring and Mitigation Strategies

Given the potential risks associated with SRB and SRA, proactive monitoring and mitigation strategies are essential for the safe and efficient operation of gas and hydrogen storage facilities.

1. Regular Monitoring: Implementing regular microbial monitoring programs helps detect the presence and activity of SRB and SRA, allowing for timely interventions.

2. Chemical Treatment: The use of biocides and other chemical treatments can help control microbial growth. However, these should be carefully selected to avoid exacerbating the problem.

3. Environmental Control: Maintaining optimal environmental conditions (e.g., pH, temperature) can help reduce microbial activity and limit H2S production.

4. Advanced Technologies: Employing advanced technologies such as high-pressure incubation and 16S-profiling or metagenome sequencing can provide deeper insights into microbial communities and their dynamics within storage systems.

Conclusion

Understanding and managing the activity of sulfate-reducing bacteria and archaea is crucial for ensuring the integrity, safety, and efficiency of gas and hydrogen storage infrastructure. By comprehensively monitoring these microorganisms and implementing targeted mitigation strategies, operators can mitigate the risks associated with H2S production, sour gas, and microbiologically influenced corrosion (MIC), ensuring the long-term viability of their storage systems.

Stay ahead in the energy sector by prioritizing microbiological management in your storage operations. For more insights and solutions tailored to your specific needs, contact us today. Together, we can ensure a sustainable and secure energy future. Microbify your full service provider around microbiologically-influenced corrosion (MIC), biocorrosion and sulfate-reducing bacteria.