Methanogenic potential of lignites in Poland

• Published in: International journal of coal geology 2018-08, Vol.196, p.201-210
• Main Authors: Szafranek-Nakonieczna, Anna, Zheng, Yanhong, Słowakiewicz, Mirosław, Pytlak, Anna, Polakowski, Cezary, Kubaczyński, Adam, Bieganowski, Andrzej, Banach, Artur, Wolińska, Agnieszka, Stępniewska, Zofia
• Format: Article
• Language: English
• Subjects: 2-bromoethane sulphonate; GDGTs; Lignite; Lipid biomarkers; Methanogenic potential
• ISSN: 0166-5162; 1872-7840
• DOI: 10.1016/j.coal.2018.07.010

Microbial coal gasification is of great interest due to the necessity to develop more environmentally friendly methods of energy production. The two main lignite deposits in Poland (Bełchatów and Turów) have been studied for their natural methanogenic potential. The biological origin of gases occurring in the investigated strata was confirmed by carbon stable isotope fractionation. Methanogenesis was examined via long-term anaerobic microcosm incubations which were performed using coal extracted from upper- and lower- most parts of the deposits at 10 to 40 °C. Present-day methane formation was distinguished from physical desorption by application of 2-bromoethane sulphonate (BES), an inhibitor of terminal methane formation steps. Furthermore, glycerol dialkyl glycerol tetraethers (GDGTs), were used to reconstruct the palaeoenvironmental conditions and explain how the lignite environment affects the methanogenic consortia. The data obtained reveal that microbial degradation of lignite occurs in the uppermost layers of the coal seam at the Bełchatów lignite mine. Methane release was up to 0.064 ng CH4 g−1 day−1 at 30 °C. Biomarker analysis shows high abundance of GDGT-0 confirming the presence of methanogenic Archaea and implies that pH was an important factor regulating the development and activity of organic matter-degrading microbiota under neutral conditions as the most favourable for the methanogens. Inactivation of methanogenic pathways by BES led to stimulation of bacterial respiration, which suggests the presence of an active bacterial community, putatively involved in the decomposition of lignin. The biomarker analysis, depicting metabolic capabilities of the microbiota (especially GDGT-0 and GDGT-0/crenarchaeol ratio) and recognition of palaeoenvironmental conditions, is a useful tool to determine the methanogenic potential of coals. •Methane production in lignite from the Bełchatów mine is up to 0.064 ng CH4 g−1 day−1.•Biomarkers confirm the presence of methanogenic Archaea in lignite•pH regulated activity of organic matter-degrading microbial community•Bacterial respiration was stimulated by 2-bromoethane sulphonate•GDGTs can be applied when considering coal as a subject of biogasification