Methane generation potential of Thar lignite samples

•Thar lignite samples showed susceptibility to biological degradation to methane.•WBC-2 provided a tool for assessing methane generation potential in lignite.•Petrographic studies of samples indicate early maturation stage of Thar coalfield.

Eleven representative lignite samples from the Thar coalfield, Pakistan were subjected to a bioassay, based on mixed methanogenic bacterial consortium (WBC-2). The samples were characterized on the basis of chemical and petrographic studies in order to determine the geological stage of coal resource. Under anaerobic conditions in sealed serum bottles, the generation of methane was observed from six coal samples in the range of 3.7 to 23.2 μmol/g of coal (2.13 to 16.33 scf/ton of coal). This methane generation from Thar lignite samples may be considered as an indicative index of the presence of biogenic coalbed methane in the reservoir. The residual coal, after methanogenesis, was investigated and prospected on a preliminary basis for the release of humic materials. Conclusively, further exploration of biogenic methane production from low rank coals and subsequent extraction of soil conditioning agents from residual coal can be followed as an alternative route of coal conversion technologies for obtaining multiple value-added chemical entities from low rank coal.