Waste to energy is the production of heat and/or electricity mainly with the usage of garbage as a fuel or as their official term is Municipal Solid Waste (MSW). MSW includes all solid waste produced by households, apartment building, schools and commercial establishments that local authorities collect. Waste to energy is considered a type of energy recovery and there are two main methods:
- incineration which is done via direct combustion of the waste and
- Transformation of waste into combustible gaseous form (i.e. methane, ethanol) via thermal treatment without direct combustion (i.e. pyrolysis, gasification.)
The most popular method out of the two is incineration. Incineration is a quite controversial method as it often raises environmental concerns. This is because municipal solid waste contain a diverse mix of waste materials, some benign and some very toxic such as heavy metals, trace organics, such as dioxins and furans. As a result there is a debate on whether waste to energy can be considered biomass energy. Biomass is a renewable energy source that uses as fuel material of biological origin. Consequently, the production of biomass does not add into the co2 environmental concentration as its fuel can be replaced and recapture the emitted carbon dioxide used during its production i.e. in the case of burning wood or corn you can replant. Waste to energy on the other hand does not use exclusively biological material, even though the greatest portion of MSW is of biological origin, and thus opponents of it claim that is not a sustainable form of energy. The counterargument is that WTE is sustainable since people will continue to produce garbage of non-biological origin. In addition, regarding harmuful emissions (dioxins etc), modern techniques applied to new WTE plants have minimized the amount released to acceptable levels. Finally, a large portion of the risk can be eliminated via thorough pre-sorting of MSW at plants sites to exclude toxic materials from being used as fuel thus reducing pollution emissions to a minimum. Hence, waste to energy can help in the reduction of Landfilling since it reduces the volume of waste by 95%. In addition, as oppose to WTE, Landfilling creates methane which is much more harmful to the environment since it contributes 20 to 25 times more to global warming than the CO2 emissions.
In the USA, according to the US energy recovery council, there are 87 WTE plants producing 2,700 megawatts that results into 17 million of kwh per year which is enough to meet the needs for power for 2 million households. In the EU incineration is more popular. According to the confederation of European Waste to energy plants (CEWEP) the plants in Europe can supply annually about 13 million inhabitants with electricity and 12 million inhabitants with heat.
Waste to energy is produced mainly by biological material and thus the energy produced is mainly biomass energy along with all its pros and cons. In addition significant steps have been taken in recent years to make sure that the portion of non biological material incinerated is harmless to the environment. Therefore, waste to energy incineration is a great way to reduce our dependency on fossil fuel and in addition to reduce CO2 emissions and Landfilling.