Waste-to-energy

  Waste-to-energy (WtE) or energy-from-waste (EfW) in its strictest sense refers to any waste treatment that creates energy in the form of electricity and/or heat from a waste source. Such technologies reduce or eliminate waste that is traditionally streamed to a "greenhouse gas" emitting landfill, or consume waste materials from existing landfills. WtE is also called energy recovery. Most WtE processes produce electricity directly through combustion, or produce a combustible fuel commodity, such as methane, methanol, ethanol or synthetic fuels.

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Incineration

Main article: incineration

Incineration, the combustion of organic material such as waste, with energy recovery is the most common WtE implementation. Incineration may also be implemented without energy and materials recovery, but this is increasingly being banned in OECD countries. Furthermore, all new WtE plants in OECD countries must meet strict emission standards. Hence, modern incineration plants are vastly different from the old types, some of which neither recovered energy nor materials. Modern incinerators reduce the volume of the original waste by 95-96 %, depending upon composition and degree of recovery of materials such as metals from the ash for recycling^[1].

WtE technologies other than incineration

There are a number of other new and emerging technologies that are able to produce energy from waste and other fuels without direct combustion. Many of these technologies have the potential to produce more electric power from the same amount of fuel than would be possible by direct combustion. This is mainly due to the separation of corrosive components (ash) from the converted fuel, thereby allowing a higher combustion temperatures in e.g. boilers, gas turbines, internal combustion engines, fuel cells. Some are able to efficiently convert the energy into liquid or gaseous fuels:

Thermal technologies:

• Gasification (produces combustible gas, hydrogen, synthetic fuels)
• Pyrolysis (produces combustible tar/biooil)
• Plasma arc waste disposal In infancy

Non-thermal technologies:

• Anaerobic digestion (Biogas rich on methane)
• Ethanol production
• Mechanical biological treatment
  • MBT-Anaerobic digestion
  • MBT-Refuse derived fuel

See also

• Incineration
• List of solid waste treatment technologies
• Waste management

References

1. ^ Waste to Energy in Denmark by Ramboll Consult