How does Waste-to-Energy Work?

Waste-to-energy Plant in East Rockingham, Western Australia

Waste-to-energy is an important waste management method that plays a vital role in recycling and generating electricity. By burning municipal solid waste, waste-to-energy plants are able to produce steam that powers a turbine to generate electricity. Here’s a closer look at how waste-to-energy plants work.

Municipal solid waste, also known as MSW or garbage, is burned as fuel in a waste-to-energy plant. This type of plant is sometimes called an incineration facility or energy-from-waste facility. MSW is mostly comprised of energy-rich materials such as paper, plastics, yard waste, and wood products. Out of every 100 pounds of MSW in the United States, approximately 85 pounds can be used as fuel.

Burning MSW in a waste-to-energy plant creates steam. This steam powers a turbine that generates electricity. One advantage of this process is that it significantly reduces the volume of waste. For example, 2,000 pounds of MSW can be reduced to ash weighing 300 to 600 pounds—a volume reduction of 87%.

There are different types of technologies for waste-to-energy systems. The most common type used in the United States is the mass-burn system. This system burns unprocessed MSW in a large incinerator with a boiler and generator for producing steam and electricity. Other types of Waste-to Energy Systems include:

• The refuse-derived fuel system – processes MSW to create pellets or flakes that are burned in a boiler to create steam for powering a turbine.
• The plasma gasification system – uses an electric arc to convert MSW into a plasma gas that produces heat for generating electricity.

The Clean Air Act Amendments of 1990 require new waste-to-energy facilities to use the best available air pollution control technologies (BACT) to minimize emissions. As a result, modern waste-to-energy facilities have some of the lowest emission rates of any industrial process. In addition, they are subject to stringent air emission standards set by the U.S. Environmental Protection Agency (EPA)

Waste-to-energy facilities also have to meet the EPA’s Resource Conservation and Recovery Act (RCRA) standards, which are designed to protect human health and the environment from the potential hazards of solid waste disposal. These standards cover all aspects of MSW management, from collection to disposal, including waste-to-energy

The bottom line is that when waste-to-energy facilities are properly designed, constructed, and operated, they can be an important part of an effective and environmentally sound solid waste management system.

Although waste-to-energy plants cause more air pollution than natural gas plants, they release less carbon and methane into the air than if the garbage was left to decay.

Waste-to-energy plants are very clean and cause little pollution. In fact, they are one of the cleanest burning fossil fuel power plants. The emissions from a modern waste-to-energy plant are well below the emission limits set by the U.S. Environmental Protection Agency (EPA)

A typical waste-to-energy plant emits:

• Carbon dioxide (CO2) – This is the same greenhouse gas that we exhale with every breath and that plants need for photosynthesis
• Water vapor – This is the same water vapor that we exhale with every breath and that forms clouds in the sky
• Nitrogen oxide (NOx) – This is a pollutant that can cause smog and contribute to acid rain
• Sulfur dioxide (SO2) – This is a pollutant that can cause soot and acid rain
• Carbon monoxide (CO)
• Particulate matter (PM or soot)
• Lead
• Mercury
• Cadmium
• Hexachlorobenzene (HCB)
• Dioxins and Furans

These emissions are well below the emission limits set by the EPA. In fact, the emissions from a modern waste-to-energy plant are lower than the emissions from a natural gas power plant of the same size.

The Niagara Falls Wastewater Treatment Facility uses a waste-to-energy process to generate enough electricity to power the facility and sell electricity back to the grid. The plant produces about 24 megawatts of electricity—enough to power more than 20,000 homes.

The Covanta Waste-to-Energy plant in Alexandria, Virginia, serves 400,000 people and businesses in the city and county of Alexandria and Arlington. It burns non-hazardous household garbage at high temperatures to produce steam for renewable energy generation. Covanta converts and processes more than 350,000 tons of waste that would otherwise go to landfills into energy in this manner.

By nullifying the amount of waste sent to landfills, Covanta Alexandria has single-handedly saved 331,000 tons of carbon dioxide from being emitted into the atmosphere. To provide some context, that’s equivalent to removing 65,000 vehicles from roads for an entire year.

Burning MSW in a waste-to-energy plant creates steam. This steam powers a turbine that generates electricity. One advantage of this process is that it significantly reduces the volume of waste. For example, 2,000 pounds of MSW can be reduced to ash weighing 300 to 600 pounds—a volume reduction of 87%.

While often overlooked, waste-to-energy plants play an important role in society by recycling municipal solid waste and generating electricity. If you’re interested in learning more about how these facilities work, this blog post has provided a brief overview.