Discussion
Access to energy resources, economic development and environmental pollution, which in turn
threaten human health, are major challenges facing developing countries today [207]. Economically
feasible and efficient small scale biogas digesters could be the answer of solving some of these
problems and needs. By enhancing energy availability and simultaneously protect the surrounding
environment such as soil, water and air, a lots of benefits could be gained. Most of small-scale
digesters are concentrated in developing countries with India and China as leading countries
accounting for the highest share.