Biogas Production From Agricultural Residues: A Review

Nowadays, the energy security as well as the environmental concerns has made great attempts to find economically and environmentally friendly energy resources. Biogas production via anaerobic digestion has been shown as a sustainable, renewable and carbon neutral energy source which can reduce the global fossil fuels dependency. Agricultural activities generate huge amounts of organic residues annually worldwide. These are including crop residues, straw, stalks, branches, leaves, waste from pruning, bagasse, residue from cotton ginning, oil cakes and animal manure. Traditional methods such as burning of these residues cause adverse effects on the environment such as greenhouse gas emission and pollution of air and water, while they could be sufficiently converted into valuable products through anaerobic digestion process. In order to enhance the efficiency of anaerobic digestion of the agricultural residues, a sufficient pretreatment may be necessary to make the feedstock ready for microbial decomposition. Besides, the optimization of microbial activity of anaerobic digestion via manipulation and control of operational parameters is necessary and important. This paper presents a comprehensive review on the latest studies investigating the potential of agricultural wastes as feedstock for biogas. The review includes the investigations on the biomethane potential of agricultural residues as well as the investigated pretreatments and operational conditions for the improvement of anaerobic digestion of agricultural residues.