Modeling of microbial methane generation from coal and assessment of its impact on flow behavior

Abstract

Enhanced microbial conversion of coal to methane has been a topic of research in the scientific community since its inception in the mid-nineties. Significant advances have since been made and the technique is now termed Microbially Enhanced Coalbed Methane (MECBM), with tremendous promise in the energy industry. However, analytical treatment of the bioconversion of coal using mathematical modeling is lacking. This paper is devoted to developing a fundamental outlook of the process of bioconversion of coal to methane using the concept of logistic population growth. The modeling exercise using laboratory results sheds light on the correlation between microbial growth rate, the ability of the environment to support the microbial population and environmental factors controlling the two. Furthermore, simulation of the impact of the technology on modifying the flow behavior of coal under in situ conditions is presented. The results demonstrate that the model can be used as a useful tool to evaluate the effect of any parameter, whether controllable for optimum gas production or an outcome of continued bioconversion, on actual gas production. The analysis of the results shows that the impact of environmental parameters, such as temperature, particle size and pH of the medium on bioconversion process can be optimized. Finally, it is shown that changes in flow behavior of coal are not very significant and can possibly even be negative.