Methane emission from fixed dome biogas plants in hilly and plain regions of northern India.

Methane emissions from the slurry displacement chambers of different fixed dome type biogas plants (Capacity 2 m3) installed in hilly and plain regions of northern India were quantitatively estimated. The slurry temperature in the biogas plants in the hilly areas of Himachal Pradesh at an altitude of 1300 m above mean sea level remains below the lower mesophilic range (16-25 degrees C) during most part of the year. Difference in the ambient temperature under the two climatic conditions of Hills and plain regions affects the CH4 flux. Methane fluxes from the plants ranged between 7 and 120 gm(-2) d(-1). In northern plain, temperature remains warm (21-33 degrees C) throughout the year except during winter (December to January) when there is a steep fall. Seasonal emission of CH4 ranged between 10 and 178 gm(-2) d(-1). The annual average methane emission from the biogas plants in plain areas was 83.1 gm(-2) d(-1) as compared to 43.1 gm(-2) d(-1)in the hilly areas. Annual contribution per plant to the global methane budget from a fixed dome biogas plant (Cap 2 m3) in plain region of northern India was 53.2 kg as compared 22.3 kg in hilly area.