Did you know that your non-recyclable waste can be used to produce energy that is used to power buildings, greenhouses, and even cars? That’s just what waste-to-energy (WTE) does by producing heat, electricity, and fuel from our garbage[sc:1]. WTE helps the environment because it reduces the need to use fossil fuels as a source of energy and it also reduces powerful methane greenhouse gases that are produced by landfills[sc:2].
There are three types of Municipal Solid Waste (MSW) combustion technologies
- Mass burn facilities
The most common type of MSW combustion technology, waste is burned inside a primary chamber that contains a large volume of air. The excess air allows for sufficient oxygenation of the trash so that it will all burn properly. The MSW is burned on a moving and vibrating grate that agitates the waste and allows for maximum air exposure.
The heat that is produced by burning the MSW is used to create steam that turns a turbine in an electricity generator. 99% of the particulate matter that is present in this steam is removed by efficient filtration.
The ash (approximately 5-15% of the processed MSW volume) from the burning of materials is first processed to remove any scrap metals that are recyclable and then the remaining ash is brought to a landfill.
- Modular systems
These systems burn unprocessed MSW in similar ways as the Mass Burn Facilities, but on a smaller, portable scale that can be brought to different sites.
- Refuse derived fuel systems
The MSW is shredded and the non-combustible waste is separated. The remaining combustible MSW is turned into fuel that can be used in specific types of furnaces or added to conventional boiler systems[sc:3].
Landfill gas (LFG) energy recovery
In addition to combustion WTE technologies that burn waste to produce energy, landfill methane from landfill gas can also be captured and burned for energy.
Landfill gas is naturally produced by waste buried in landfills as organic materials in the waste decompose. Approximately 50% of this gas is carbon dioxide (CO2) and the other 50% is methane (a greenhouse gas that is 25 times more potent than CO2). MSW landfills are a major source of man-made methane gas, so by utilizing landfill gas as an energy source, we are reducing greenhouse gas emissions.
The landfill gas is extracted with wells and flares or vacuums, and then it is collected at a central point where it will be distributed to wherever it is needed. Landfill gas is flared, used to generate electricity (for uses such as engines, turbines, microturbines, and fuel cells), used directly in boilers, dryers, kilns, greenhouses, as a fuel source in industry and manufacturing, for the cogeneration of both heat and electricity, or processed into a higher-grade fuel where it can be used directly or made into an automotive fuel[sc:4].
While we all should reduce our consumption and waste, waste-to-energy technology can provide a viable energy resource and reduce harmful greenhouse gases. This is another example of how we can create solutions from problems, and make our existing waste stream a little more sustainable.