Basic Study on the in-situ Biogenic Methane Generation from Low Grade Coal Bed

Abstract

In the present work, a basic study on the in-situ biogenic methane generation from low grade coal bed was conducted. Lignite from Indonesia was used as a sample feedstock. A series of BMP (Biochemical Methane Potential) tests were carried out under the different experimental conditions. Although nutrients and anaerobic digester sludge were added to the coal, the produced amount of methane was limited. Both temperature control and particle size reduction showed little effect on the increase of methane potential. When rice straw was added to lignite as an external carbon source, methane yield of 94.4∼110.4 mL/g VS was obtained after 60 days of BMP test.The calorific value of lignite after BMP test decreased (4.5∼12.1 %) as increasing the content of rice straw (12.5∼50 wt % of lignite), implying that anaerobic digestion of rice straw led to partial degradation of lignite. Therefore, rice straw could be used as an external carbon source for the start-up of in-situ biogas generation from low grade coal bed.