A Saifuddin creator Harada, Hideki Chairperson Tentscher, Wolfgang Examination Committee Chongrak Polprasert Examination Committee Zhuang, Ya-Hui Examination Committee Bhattarai, Kiran K. Examination Committee Schroder, Hans Examination Committee Government of France Scholarship Donor text series technical report th Bangkok Asian Institute of Technology 1991 continuing eng 145 p. The study has been conducted by collecting the required data from concern government departments, various international agencies and literature surveys, to find the present state of biogas technology in China, India, Nepal, Pakistan and Thailand to evaluate the reasons of.successes and failures. The biogas technology has been found economically viable in these countries in terms of both the pay- back period and the benefit cost ratio when replaced partially by firewood and kerosene oil (7 : 3 Ratio) used for cooking and lighting. The shortest payback period is in Pakistan (2.39 years ) for producing 3 m3 gas from a floating drum digester. While for fixed dome digester the shortest pay- back period in China ( 2.59 years ) for producing the same quantity of the gas. The Benefit cost ratio is high as 1.92 for Indian fixed dome plant and as low as 1.03 for Chinese fixed dome plant. The present share of biogas in rural energy demand was also evaluated and found to be negligible except in China and India (1.0 and 0.75% respectively). By collecting 50% of the available waste from the cattle, buffaloes, pigs, poultry and humans in the rural areas of the respective countries, the biogas production can be increased and the share of biogas in the rural energy demand can be also increased. Similarly biogas share in rural energy demand can be further increased by 60 and 70% collected human and animal waste treatment. Biofertilizer can be also made available from these biogas plants in substantial quantity China and Nepal can meet their entire present demand of mineral fertilizer of 50% collected waste, India and Thailand can meet the present. mineral fertilizer demand from the treatment of 60% collected waste. Pakistan still needs more efforts to the mineral fertilizer demand by biofertilizer production meet. This can save millions of dollars, which could be used for the development of the country and to raise the standard of living of the common people. The present deforestation rate can also be controlled by biogas technology as wood is the principal fuel in the rural area of these countries. Gas production from 50% of the collected waste can stop the present deforestation in Pakistan, while from the gas production of 60% of the collected animal and human waste in India, and 70% of the collected waste in Nepal can stop the present. deforestation. The rate of deforestation can be checked in China but still needs more efforts to stop it completely. Comparison has also been made on the present state of technology in these countries with particular emphasis on plant construction techniques, present feed materials and different operational parameters. It has been evaluated that the present Chinese fixed dome technology is the best available choice both in terms of fixed and maintenance cost except for the shortcoming of uneven gas pressure. The present utilization of slurry is evident only in China. The lack of training facilities and availability of trained staff are other reasons preventing the dissemination of biogas technology. Social accept ability of biogas is good except in some areas of India, Nepal and Pakistan. There is still stiff resistance in using human excreta as potential raw material in the subcontinent but is accepted well in China and Thailand. A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering Thesis (M.Eng.) - Asian Institute of Technology, 1991 Biogas plants Asia Asian Institute of Technology. http://203.159.5.9/ait-thesis/detail.php?q=B17413 http://203.159.5.9/ait-thesis/detail.php?q=B17413 170399 20260817173404.0