As the world increasingly shifts towards sustainable energy solutions, the search for cleaner, more efficient ways to extract coal bed methane (CBM) is gaining momentum. CBM has emerged as a significant unconventional natural gas resource, contributing to global energy production. Primarily consisting of methane, CBM is an atypical hydrocarbon gas. CBM is formed and stored in coal seams through adsorption. CBM extraction involves the recovery of methane gas trapped within coal seams, offering both economicand environmental advantages(Figure 1). Microbial eCBM is an innovative biotechnological approach that involves the use of microorganisms to enhance the production of methane from coal seams. It is considered a cleaner and more sustainable method for extracting methane, as it can unlock methane from non-extractable coal reserves. It has the potential to contribute significantly to natural gas supply, particularly in regions with large coal resources but limited traditional gas extraction methods.

How does Microbial eCBM Work?

The two primary routes of microbial enhancement in eCBM technology are:

Bio-stimulation: This involves injecting nutrients into coal seams to stimulate the growth of indigenous methanogenic microbes that naturally produce methane.

Bio-augmentation: This involves the introduction of external methane-producing microbes along with nutrients to further increase methane production.

Microbes interact with the coal matrix and help to convert coal into methane gas (Figure 2). They primarily function by:

Methanogenesis – Methanogens can directly produce methane from coal through a process known as microbial methanogenesis.

Coal Degradation – Microbial communities help degrade the complex organic structures within the coal, making it easier to release trapped methane.

Water Reduction – Some microbes reduce the water saturation in coal seams, improving the permeability and allowing for easier methane release.

Synergistic Effects – The interaction between different microbial species can enhance the overall bioconversion process, maximizing methane production.

Benefits of Microbial eCBM Technology

Microbial eCBM technology boosts CBM production by enhancing methane yield, especially in low-permeability seams, while offering environmental and cost benefits. It reduces reliance on energy-intensive methods, minimizes water usage, and lowers operational costs by avoiding extensive modifications. Additionally, it improves well productivity and long-term production potential, making it a sustainable and efficient alternative to conventional CBM extraction techniques.

In field trials conducted by TERI, the bio-stimulation process resulted in a threefold increase in methane production from a CBM well. Bio-augmentation at Jharia led to more than a twofold increase. The microbial-enhanced CBM technology was successfully tested in over 12 CBM wells, including those operated by ONGC and Essar.

Conclusion

Microbial eCBM technology is a promising frontier in the field of coalbed methane production. By harnessing the power of microorganisms, this technology can significantly enhance methane recovery, reduce environmental impact, and offer a more cost-effective solution to the energy industry. As research and development continues, microbial eCBM has the potential to become a cornerstone of clean energy production, helping to meet global energy demands while advancing the goals of carbon neutrality and sustainability. #

Dr Meeta Lavania is Senior Fellow, Environmental & Industrial Biotechnology Division, TERI; Dr Banwari Lal is Senior Fellow & Senior Director, Environmental & Industrial Biotechnology Division, TERI.