Microbial formation of methane from pretreated lignite at high salt concentrations

During recent years, the interest in the use of lower-ranked coals and lignite as energy sources has greatly increased. One of the currently investigated possibilities is the conversion of lignite material into gaseous fuels. It was suggested that biological gasification processes for coal and lignite may offer potential advantages of lower cost and higher efficiency that the various conventional thermal processes. One of the methods proposed for the biogasification of chemically pretreated lignite makes use of underground salt caverns as cheaply available bioreactors; in this case the biological conversion of lignite breakdown products to methane has to occur at high salt concentrations, as salt will dissolve from the walls of the caverns. The potential conversion of simple aromatic compounds, such as can be found in chemically pretreated lignite, to methane under anaerobic condition is well established.