Also see the urg- words that have been "transformed" from the basic elements of this unit.
This waste-to-energy is possible, and convenient, when the heat generated by burning the "waste" is high enough to warrant satisfactory combustion conditions and to make enough energy available to overcome losses and auxiliary consumption.
Characteristics of waste-to-energy production
- Waste-to-energy is the offspring of the incineration of materials, which were originally introduced to sterilize and to reduce the volume of useless substances by burning it in a furnace.
- Modern waste-to-energy plants allow the export of energy, with very low environmental impact.
- The waste-to-energy plant consists of four basic sections: waste combustor, recovery boiler, flue gas treatment, and steam cycle.
- The design of the combustor varies widely with the waste characteristics: physical state (solid versus liquid), size distribution, heating value, ash and moisture content, etc.
- Municipal solid waste is typically burned on a moving grate, where it is kept 20-30 minutes until it is completely burned.
- The hot gases generated in the combustor go through the recovery boiler to generate steam, which is used directly as a heat carrier or it is sent to a steam turbine to produce power.
- Flue gases are treated by adding reactants called sorbents and by filtering the particulate matter.
- A modern, large plant, treating a half-million tons of municipal solid waste per year, can generate more than 400 million kWh per year, meeting the electricity needs of more than 150,000 families.