Sustainability and contribution of household biogas plants to energy transition in Nepal.

Household biogas can significantly contribute to sustainable energy transition by supporting the decarbonisation and modernization of the cooking energy sector. Nearly 450,000 household biogas plants were reported to have been installed in Nepal as of 2023. This study assesses their sustainability using large-scale household survey data combined with statistical analysis. A face-to-face survey of 2,559 households with biogas plants was conducted across ten districts, spanning the three most inhabited physiographic regions of the country. The interviews were conducted using a structured questionnaire to collect demographic and socio-economic characteristics, information on the functionality of biogas plant components (including from visual inspections), and the reasons, if any, for biogas plant dis-adoption. This study used descriptive and logistic regression analysis to identify factors that influence sustained use and dis-adoption. At the time of the survey, 54% of biogas plants had been abandoned, primarily due to a malfunctioning mixer, the main valve or the gas pipe. Statistically significant contributors to dis-adoption included plant operators having too small a herd of livestock to produce sufficient biogas feedstock, failure to conduct routine digester and outlet cleaning, and lack of post-installation repair and maintenance services. Moreover, many systems that were still in use were not performing optimally, producing only 0.4 m