The economic value and satisfaction of substituting LPG in households by a biogas network: A case study of Bo Rae Subdistrict in Chai Nat Province Thailand

Economic value and satisfaction of substituting LPG by a biogas network in households of Bo Rae Subdistrict, Chai Nat Province, Thailand were investigated. This project was undertaken through collaboration between the Ministry of Energy and Phairat Farm. The Thai Government supported investment in the construction of biogas production and network piping systems for transporting biogas to households. Phairat Farm allocated an area of land to construct the biogas production system and provided support with the raw materials for biogas. These raw materials were pig manure and wastewater as by-products from pig farming. Income and expenses of a 15-year plan project were considered and analysed to assess the economic value using net present value (NPV), internal rate of return (IRR) and payback period (PB) in 3 case; (1) income came from payment for biogas by each household at a rate of 50 baht per month and selling dried sediments from the biogas production system, (2) income came from substituting LPG at price of 30 THB/kg and (3) income came from payment for biogas by each household, selling dried sediments, substituting LPG and selling carbon credit. Results showed that only the first case was not profitable because payback period over 15 year. Then, a biogas user satisfaction survey was also conducted using 136 questionnaires. The samples size was determined by Taro Yamane's equation to achieve 95% confidence level and ±5% uncertainty. Data were collected and analysed to measure satisfaction level in three aspects; (1) an analysis comprising management, usage, and maintenance of the biogas system, (2) environmental impact and (3) overall satisfaction level. Results showed that the samples were very satisfied with management, usage and maintenance of the biogas system. Income was only the main influential factors. For the environmental impact and overall satisfaction level, the samples were also very satisfied.