Tour of a Wheelabrator Waste-to-Energy Plant (animated)

Category: Climate & Carbon
Academic Level: High School
Publisher: Wheelabrator Technologies Inc.
Published Date: May 2007
Comment(s): 6
What is Waste-to-Energy?

Waste-to-energy is a process that converts trash into clean energy to heat, cool, and light our homes and power industry. Nationwide, waste-to-energy facilities process nearly 29 million tons of trash each year and generate enough power to meet the needs of 3 million homes. More than 36 million people in 27 states rely on waste-to-energy plants.

Modern waste-to-energy facilities differ significantly from old-fashioned municipal incinerators. Incinerators inefficiently burned trash, didn't recover any of the energy released during the combustion process, and had minimal air pollution control. The waste-to-energy process, on the other hand, recovers the heat value of combusted trash to generate steam and electricity to power homes and industry. Highly efficient combustion reduces the volume of trash by about 90 percent, and advanced pollution control systems ensure a cleaner-burning power plant.

Wheelabrator facilities use proven mass-burn technology to generate energy by feeding mixed municipal waste into large furnaces dedicated solely to burning trash. The resulting energy produces steam or electricity. Widely used throughout Europe and Japan, the process was adapted to the United States waste management marketplace largely through the innovative technological breakthroughs of Wheelabrator.

The waste-to-energy process used by Wheelabrator takes everyday trash and converts it into clean, renewable electric energy. Incoming trucks deliver trash to an enclosed reception area and dump the refuse into a concrete receiving pit. From this area, overhead cranes transfer trash into one of the boilers' feed hoppers. Inside each boiler, an inclined, reciprocating, metal grate (floor) slowly moves the refuse through the combustion process, where temperatures exceed 2000°F, in order to allow complete combustion of the trash to occur. Air to feed the combustion process is drawn from the refuse receiving building, sustaining a negative pressure there. This negative pressure prevents any "garbage" odors or dust from escaping into the outside environment.

Surrounding the grate system is a large utility-type power boiler designed to recover the thermal energy released during the combustion process. This energy is recovered in the form of high-pressure steam that is converted into electrical energy in the turbine-generator. At full capacity, a waste-to-energy plant that consumes 1500 tons per day of trash will generate more than 40,000 kilowatts of electrical energy for sale to the local electric utility company. This is the equivalent of supplying all of the electrical needs of 40,000 homes.

Emissions from the combustion process are controlled using state-of-the-art spray dryer absorbers, also known as dry scrubbers, to control acid gases, heavy metals, and organic pollutants; fabric filter baghouses to collect particulate matter; selective non-catalytic reduction systems to control ozone-forming nitrogen oxides; and activated carbon to control mercury and trace organic emissions. These control systems thoroughly clean emissions to meet all local, state, and federal environmental standards.

After the garbage is completely processed, the remaining ferrous metals are separated from the residue. As a result of the combustion and metals recovery processes, the volume of incoming garbage is reduced by more than 90%.

Wheelabrator Technologies provides reliable, long-term trash disposal for hundreds of communities through the 17 waste-to-energy facilities it operates in Connecticut, Florida, Maryland, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, and Washington. Wheelabrator's first waste-to-energy plant, located in Saugus, Massachusetts, has been in continuous operation since 1975.