Question

The calorific value of biogas is

• A. 10 - 20$mj/m^{{}^3}$
• B. 23 - 28$mj/m^{{}^3}$
• C. 35 - 40 $mj/m^{{}^3}$
• D. 5 - 10 $mj/m^{{}^3}$

Answer 1

The correct option is B 23 - 28$mj/m^{{}^3}$

The percentage of methane in the gas determines its calorific value, as the other constituents do not contribute to the energy content. The methane content of biogas is appreciably high, at 60%. This provides a calorific value high enough to find use in many energy applications, including power generation. Biogas contains roughly 50-70% CH${}_4$ and 30-50% CO${}_2$ and has a generally accepted mean calorific value of about 25 MJ/m${}^3$ (1 m${}^3$ of biogas is an equivalent of energy in 0.93 m${}^3$ of natural gas or in 1.25 kg of coal).