A review of household and industrial anaerobic digestion in Asia: Biogas development and safety incidents

Asia has the world's largest population and the largest number of biogas digesters, with implementation across 25 countries. These countries can be categorised into four groups based on their biogas development status. Asia has approximately 45.03 million biogas digesters, of which about 99.72% are household units and 0.28% are industrial digesters. Predominantly located in less developed rural areas, a substantial number of household digesters have ceased operation or been abandoned. Some Asian countries and regions are witnessing a transition from household to industrial digesters, driven by economic growth and favourable environmental policies. However, many industrial digesters smaller than 500 m 3 are underperforming, unprofitable, or inactive. Larger digesters are better managed and more sustainable. From 1958 through 2023, 163 biogas safety incidents were recorded in seven Asian countries, resulting in 321 fatalities, 220 injuries, and substantial property damage. This study identifies and discusses seven key factors influencing biogas development in Asia: climate conditions, energy demand, biowaste resources, economic development, government policy, technical service, and biogas programs. These factors range from objective and independent to external dependencies and direct, dynamic influences. Future biogas development in Asia will benefit from favourable technoeconomic growth and increased climate change awareness, supported by societal priorities and government policies. However, it must also confront and address several significant challenges.