Organic waste to biogas

Biomass, often in the form of wood, is the largest source of renewable energy in the U.S. by a significant margin. Incinerators and waste-to-energy plants have been around for decades but one form of biomass that's getting more attention is organic waste, such as yard waste and food. Organic waste can be decomposed using microbes to produce biogas, which is mostly methane, and nutrients for fertilizer. These anaerobic digester tanks pictured here in the municipality of Lidkoping, Sweden, will use waste from the local food industry as its main feedstock to make biogas, which can be used for heating or to generate electricity. Once the plant is completed, operators expect to handle 60,000 metric tons a year of waste and reduce carbon dioxide emissions by more than 14,000 metric tons annually. See related article: Next Wave of recycling? Check your dinner plate