Refuse derived fuel (RDF) is produced by processing municipal solid waste to increase the fuel value of the waste. The processing removes materials that don’t burn (such as glass and metal), as well as wet materials (e.g., food scraps), and creates a consistent sized fuel. Materials contained in RDF generally include textiles, paper and cardboard, wood, and plastics. Sometimes other petroleum derived wastes, such as tires, are included. The RDF can be combusted in waste-to-energy facilities to produce electricity. The U.S. Environmental Protection Agency estimates that in 2005, 33.4 million tons of Municipal Solid Waste (MSW) was combusted, with energy recovery in 89 MSW waste-to-energy facilities.