Waste as a Renewable Source of Energy: Current and Future Practices

Municipal Solid Waste (MSW) has been recognized by several states as a renewable source of energy. Worldwide, about 130 million tons of MSW are combusted annually in waste-to-energy facilities that produce electricity and steam for district heating and also recover metals for recycling. While being linked to environmental pollution prior to the implementation of Maximum Available Control Technology (MACT) regulations, Waste-to-Energy (WTE) was recently named one of the cleanest sources of energy by the U.S. Environmental Protection Agency (EPA) and the U.S. Department of Energy (DOE). However, the WTE industry often faces resistance and preconceptions based on past experience rather than current performance. Due to economic considerations that do not include environmental benefits, most of the U.S. MSW still ends up in landfills despite the fact that for every ton of MSW landfilled greenhouse gas emissions increase by at least 1.2 tons of carbon dioxide. While implemented research and development strategies focused on emissions, there is still a tremendous need for more efficient yet durable combustion technologies including flue gas recirculation and oxygen enrichment, environmentally and economically competitive reuse options for WTE residues, and also public education. The importance of WTE in the universal effort for sustainable development and its need for research and development resources has led to the formation of the Waste-to-Energy Research and Technology Council. Its principal goal is to improve the economic and environmental performance of technologies that can be used to recover materials and energy from solid wastes. This paper provides an overview of the current worldwide WTE practices, predominant technologies, and current research for advancing WTE as a renewable source of energy in the U.S. and elsewhere.