Renewable energy is becoming crucially important, as concern over burning fossil fuels is increasing and the price of oil continues to rise. Biogas technology has undergone great developments since the first designs in the 1970s. Large national projects are working very effectively in countries such as Nepal, India and China, where hundreds of thousands of biogas plants have been installed; and Europe has a fast-growing interest in biogas technology. This book focuses on biogas extension programmes in these countries, and demonstrates the applicability of the technology elsewhere. It provides a comprehensive overview of the existing knowledge covering: the history of biogas programmes, the technology behind them, the value of biogas effluent as compost, details of the main domestic biogas plant designs, how biogas extension programmes work, and how they could be replicated. It includes detailed diagrams and appendices on the design of biogas plants.This is essential reading for those running biogas plants, as well as students of renewable energy and engineering.