Waste-to-energy (WTE) is a reliable and renewable process of converting waste materials into electricity. Municipal waste is collected by local authorities from residential, commercial, and public origins, disposed in a central location, processed, and then combusted to produce heat and/or power.
In WTE facilities, trash is either burned directly or processed and shredded to produce a fuel before being combusted. The heat from the burning garbage boils water flowing inside boiler tubes and turns the water into steam. The steam can be put to direct use in a heating system or a factory, but it is most often used to turn a turbine-generator to make electricity. After any incombustible residue (ash) cools, magnets and other mechanical devices pull metals from the ash. The remaining ash is as much as 90% smaller in volume than the fuel source, and it is either deposited in a landfill, or in some cases, used to pave roads.
Waste Heat to Power (WH2P) harnesses the electricity-producing potential of a different form of waste. Large industrial facilities, ranging from oil refineries to paper mills, generate large quantities of heat to conduct their operations, and in most cases that heat is simply lost. By implementing a recovery unit to capture the waste heat, industrial users can generate power for their own plants, or sell it back to the grid. WH2P equipment is also used at renewable power plants to capture unused heat.
Waste power can also be generated from landfills. As trash and organic material decays, it releases gases that can be harnessed to produce energy (see Biomass).