Abundance of Waste and Energy Scarcity.- Biomass and Waste as Sustainable Resources.- Anaerobic Digestion.- Biomass and Waste Gasification.- Digesters, Gasifiers and Biorefineries: Plants and Field Demonstration.- Molten Carbonate Fuel Cells.- Solid Oxide Fuel Cells.- Fuel Gas Clean-up and Conditioning.- High-Temperature Fuel Cell Plants and Applications.- Biomethane and Natural Gas.- Electricity and the Grid.- Prospects of Hydrogen as a Future Energy Carrier.- Market and Feasibility Analysis of Non-conventional Technologies.- Concluding Remarks.