The U.S. Environmental Protection Agency’s (EPA’s) plan to regulate carbon emissions is just the latest challenge facing the U.S. electric power system. Technological innovation is disrupting old ways of doing business and accelerating grid modernization. Earlier this year, AEE released Advanced Energy Technologies for Greenhouse Gas Reduction, a report detailing the use, application, and benefits of 40 specific advanced energy technologies and services. This post is one in a series drawn from the technology profiles within that report.
Waste-to-energy (WTE) is the process of generating electricity and/or heat by combusting municipal solid waste (MSW). The MSW is burned to create steam, which then spins a turbine attached to an electric generator. There is a small amount of ash (5-15% of the volume of the processed trash) left over as a byproduct that is sent to a landfill. Although mass-burn combustion is the most widely deployed type of WTE technology, there are other technologies that are being commercialized, including gasification and anaerobic digestion. WTE plants can also include the recovery of non-combustible recyclable materials, either before or after combustion.
There are 86 WTE facilities in the United States. Located across 25 states, primarily in the Northeast, these facilities have a generating capacity of over 2 GW and process more than 28 million tons of municipal trash per year. Non-utility companies, typically subsidiaries of waste management companies, often develop, own, and operate WTE facilities. These companies use power purchase agreements (PPAs) to sell electricity to utilities and contract with trash collectors to provide the waste feedstock. Covanta Energy, one of the largest WTE companies in the United States, owns and operates the I-95 Energy/ Resource Recovery Facility, located in Lorton, Virginia, which processes more than 3,000 tons of municipal waste per day. The 80 MW facility sells enough electricity to Dominion Virginia Power to power 80,000 homes.
 Anaerobic digestion first requires separation of the organic fraction of the waste.