Biomethanization of Coal to Obtain Clean Coal Energy: A Review

Abstract

This paper entails a review on the possibility of methanization of coal using microbial tool. Biomethanization process of coal begins with biodegradation of coal by specific bacteria and fungi. As a result of this, major polymers present in coal like proteins, polysaccharides, nucleic acids and lipids are hydrolyzed to monomers like aminoacids, sugars, purines, pyrimidines and long chain fatty acids. Their subsequent fermentation forms hydrogen, CO 2 and a number of reduced compounds like alcohols, short chain fatty acids, organic acids and certain aromatics. The oxidation of these reduced compounds further leads to the formation of acetate, hydrogen and CO 2 , methylated compounds and several intermediate compounds. Syntrophic relationship exists between fermenting bacteria and methanogens. The resultant oxidized compounds of fermenting bacteria are gradually utilized by specific methanogens to form methane. Hydrogenotrophic methanogens utilize H 2 and convert CO 2 into methane. Whereas acetate is utilized by acetoclastic methanogens to generate methane. The methylated compounds are utilized for methane formation by methylotrophic methanogens.

Lignite biodegradation under conditions of acidic molasses fermentation

“…are also recognized as degraders of long chain n-alkanes (Throne-Holst et al, 2007). The Vibrio species are known for their cellulolytic activities (Ramesh and Venugopalan, 1988;Singh et al, 2012). The Erythrobacter and Paracoccus species (Alphaproteobacteria) found here in this microbial community are recognized lignin-degrading bacteria (Pandit et al, 2016).…”

“…On the other hand, these bacteria are known to play an important role in the microbial communities degrading lignite due to their lignocellulolytic activity. The Clostridium, Bacillus and Bacteroides species are capable to degrade cellulose, hemiceluloses and xylans (Singh et al, 2012). They are components of the microbial community called WBC-2 that has already been reported to have the potential to produce methane from coal (Haider et al, 2014;Jones et al, 2008).…”

Source apportionment of carbon during gasification of coal–biomass blends using stable carbon isotope analysis

“…There are various techniques available for coal gasification. Considering the huge amount of greenhouse gases generated during the process of gasification, new methods are being developed [4]. The idea of gasifying mixtures of coal and biomass is relatively new with almost zero commercial experience since the properties of coal and biomass differ significantly from each other [5][6][7][8].…”

Enhanced microbial coalbed methane generation: A review of research, commercial activity, and remaining challenges

“…This requires the activity of different groups of microorganisms that work together to catalyze the different steps of coal biodegradation. The solubilization and degradation of coal organic substrates can occur via aerobic or anaerobic pathways, depending on the environmental conditions, and these steps may be catalyzed by a wide variety of organisms including heterotrophic bacteria, fermenters, acetogens, syntrophs, and fungi (e.g., Beckmann et al, 2011;Fakoussa and Hofrichter, 1999;Haider et al, 2013;Jones et al, 2010;Scott et al, 1986;Silva-Stenico et al, 2007;Singh et al, 2012). In contrast, methanogenesis is carried out by microorganisms, methanogens, that are strict anaerobes (Hoehler et al, 2010;Zinder, 1993).…”