Acceptance and the sustained use of prefabricated biodigesters in Nepal

Biogas is one of the promising clean cooking alternatives, it has been used in Nepal for decades. However, performance often declines during colder months due to low temperatures. This study had three main objectives: (i) to assess the impact of insulation on biogas production capacity, (ii) to evaluate user acceptance and intention to continue using biodigester models, and (iii) to estimate the economic benefits for households. Twenty-two floating digesters were installed in four districts of Nepal, covering the Hilly and Terai regions. Each of the digesters was fabricated with one of the three insulation types: none, medium, or full. Digester performance was evaluated by comparing gas yield across insulation types, user intention to continue usage was assessed using structured surveys and the Technology Acceptance Model (TAM), and economic benefits were measured through avoided liquid petroleum gas (LPG) consumption and payback period analysis. Results showed that full insulation performed best, particularly in the hilly region during winter, where fully insulated digesters produced 47 % more gas on average than non-insulated units, with winter production increasing by up to 253 %. Notably, fewer than half of the digesters remained functional because of maintenance issues, manufacturing defects, and user neglect. TAM analysis revealed that user intent for continued usage was supported by Perceived Usefulness and Perceived Trust. Economic analysis revealed varying payback periods of 1.3 to 15 years, with the variation explained mainly by differences in the extent of LPG replacement. The study recommends that manufacturers increase the durability and quality of components and that users be held accountable for regular maintenance. The biogas program should focus on identifying committed users willing to accept biogas plants in the long term, ensuring the successful integration of biogas into the clean cooking transition.