Therefore, Calorific value of methane = 55 x 0.668
= 36.74 MJ/m3
Methane being the only major source of heat,
Calorific value of biogas = 0.6 x 36.74 MJ/m3
= 22.044 MJ/m3
A plant of 1 m3 capacity produces 0.7 m3 of gas per day.
Net energy in 0.7 m3 of biogas = 0.7 x 22 MJ
Net energy in 0.7 m3 of biogas = 15.4 MJ
Assuming that the efficiency of a biogas stove and LPG
stove is the same
Energy provided per month = 15.4 x 30
Energy provided per month = 462 MJ
Therefore a biogas plant of 1 m3 capacity is equivalent to
65% of an LPG cylinder per month.