Economic review of different designs of biogas plants at household level in Pakistan

Energy shortage in developing countries is one of the major challenges for sustainable development. Such challenges can be met and managed via indigenous, clean and reliable alternate energy sources like biogas and bioenergy especially at household levels. The household biogas technologies are now flourishing and conveniently accessible through certain Government and NGO funded schemes. In the current study household scale floating drums and fixed dome type biogas plants and their economic aspects were reviewed along-with technological and operational assessments. The results shown that 1 kW of energy can be generated from 0.65 m(3) of biogas by such household biogas units, furthermore it was evident that fixed dome type biogas plants were more economical with shortest payback period of about four months. Additionally effluent slurry being generated by such biogas plant can be a profitable provision in-terms of bio-fertilizer for agricultural. Overall the study results deliberated an optimistic picture for a developing country like Pakistan on the basis of installation of such small household biogas plants and utilizing indigenous technologies and feedstock. The net annual savings calculated were as US$ 837.67, US$ 829.03 and US$ 845.25 for steel floating drum type, fiberglass composite (FRP) floating drum type and fixed dome type household biogas plants, respectively.