Household anaerobic digester for bioenergy production in developing countries: opportunities and challenges.

Access to clean and affordable energy is vital for advancing development objectives, particularly in rural areas of developing countries. There are some three billion people in these regions, however, who lack consistent access to energy and rely on traditional solid fuels such as firewood, cattle manure, and crop residues for meeting cooking and heating needs. Excessive use of such highly polluting resources creates serious environmental, social and public health issues. In this context, household digesters (which convert readily available feedstocks such as cattle manure, human excreta, and crop residues into biogas) have the potential to play a significant role in supplying methane as a clean, renewable energy resource for remote geographies. In addition to bioenergy production, the slurry generated from anaerobic digestion is rich in nutrients and can improve the physical, chemical, and biological attributes of soil when applied to agricultural land. This type of approach has the potential to significantly reduce greenhouse gas emissions while simultaneously improving the quality of life. Despite a long history of research and innovation for the development and optimization of household digesters, little is known and has been reported for the application of these systems in decentralized communities. The primary purpose of this paper seeks to review the dearth of literature pertaining to small-scale anaerobic digesters in remote geographies and in regions where much of the world's population reside.