In recent years, there has been a steadily increasing in the amount of solid waste due to the increasing human population and urbanization. Waste materials are generated from manufacturing processes, industries and municipal solid wastes (MSW). Waste-to-energy (WTE) technologies convert waste matter into various forms of fuel that can be used to supply energy. Today, a new generation of WTE technologies is emerging which hold the potential to create renewable energy from waste matter, including MSW, industrial waste, agricultural waste, and waste byproducts. There are four major methods for conversion of organic wastes to synthetic fuels: (1) hydrogenation, (2) pyrolysis, (3) gasification, and (4) bioconversion. (C) 2010 Elsevier Ltd. All rights reserved.