How MSW Plants Turn Waste to Energy

Municipal solid waste, or MSW, can be recovered and turned into biofuel. This process of turning garbage into fuel works twofold: it lessens the world’s dependence on fossil fuels and it keeps trash out of landfills. When MSW is burned rather than buried in landfills, the volume of waste is reduced by about 87%.

In honor of Earth Day 2019, we’re taking a closer look at the process of waste-to-energy conversion and the benefits it provides.

Waste-to-Energy Plants for Trash Conversion

When a waste management truck hauls away non-recyclable waste from residences or businesses, it is taken to a waste-to-energy plant to be converted into energy. Once it arrives by truck, the load is deposited into a trash storage bunker, where it will be sorted by an overhead crane. Once sorted, the waste is ready to go through the combustion process, which is the most commonly used and oldest thermal process.

Other methods of energy conversion include:

• Gasification: waste materials are converted into a mixture of combustible gases in an environment with limited amounts of oxygen (as opposed to combustion, which takes place in an oxygen-rich environment).
  
• Pyrolysis: similar to gasification, but the difference is the temperature. Where gasification uses high temperatures of 900 to 3,000 degrees Fahrenheit, pyrolysis uses relatively low temperatures of 600 to 1,499 degrees Fahrenheit.
• Fermentation: microorganisms and yeast produce liquid ethanol from biomass and biowaste materials. Dilute ethanol is distilled to produce a biofuel grade ethanol, ethyl alcohol.

Since combustion is the most commonly used conversion technology, however, that’s the process many waste-to-energy plants are interested in.

Converting Water to Steam

During the combustion process, sorted waste is lifted into a combustion chamber to be burned. The heat released during mass burning converts water to steam. The steam then produces electricity through a turbine generator. Early waste combustion systems were more simple, producing heat and carbon dioxide as well as other pollutants. Now, most incinerators have air-pollution control systems in place to clean flue gases before they are released into the air.

As water is converted into steam, flue gases are treated to remove pollutants like mercury, acid gas, and particulates. After undergoing pollution control tests, cleaned flue gases and water vapor are released. At the same time, ash from the burned waste is collected and transported via conveyor through the plant, using equipment like the SYNCRO-COIL Bottom Ash Vibratory Conveyor. The ash is then taken to a landfill for further processing.

Ash Filtering and Processing in Landfills

At a landfill, a filtering system captures particulates, where more than 99% of particulate matter is removed. The captured ash particles are collected and transported to the ash discharger, where they are wetted to prevent dust. After mixing with bottom ash from the grate and screened for bulk material with machines like our FINGER-SCREEN for Waste to Energy, the ash residue is loaded into covered trucks and taken to another landfill designed to protect against groundwater contamination.

Quick Facts About Waste-to-Energy

• There are 86 facilities in the U.S. that recover energy from MSW.
• These facilities can produce 2,720 megawatts of power per year by processing more than 28 million tons of waste.
• 4 tons of waste equals 1 ton of oil and 2 tons of waste equals 1 ton of coal.
• The 468 million metric tons of trash produced in North America annually could provide 47 billion liters of ethanol—roughly the same amount produced from corn, which supplies about 10% of U.S. gasoline demand.

Go Green with General Kinematics

Our waste-to-energy equipment produces clean, renewable energy from handling and transporting MSW materials and residual ash. General Kinematics’ systems require less horsepower and therefore less energy consumption and electrical costs. Whatever reusable products you work with, General Kinematics has solutions for the reclamation process. Learn more about our environmentally responsible designs today.