Waste-to-energy (WtE) and energy-from-waste (EfW) are methods that turn waste into useful energy, such as electricity or heat, in special plants called waste-to-energy facilities. As a way to recover energy from waste, WtE is important for managing waste and producing sustainable energy. It helps reduce the amount of waste sent to landfills and provides an alternative source of energy.

The most common WtE method is burning waste directly to create heat. This heat is used to produce electricity through steam turbines. This process is widely used in many countries because it helps remove waste while also generating energy, making it an efficient way to manage waste and create power.

Other WtE methods focus on turning waste into fuel. For example, gasification and pyrolysis are processes that break down organic materials using heat and chemicals without oxygen to create syngas, a type of synthetic gas made mostly of hydrogen and carbon monoxide, with small amounts of carbon dioxide. Syngas can be changed into fuels like methane, methanol, ethanol, or synthetic fuels, which are used in industries or transportation.

Another method is anaerobic digestion, a biological process that uses microbes to break down organic waste and produce biogas, which is mainly methane and carbon dioxide. This biogas can be used to create energy or processed into biomethane, a cleaner fuel that can replace natural gas.

The WtE process supports circular economy goals by turning waste into valuable resources, reducing reliance on fossil fuels, and lowering greenhouse gas emissions. However, challenges exist, such as managing emissions like dioxins and furans from WtE plants to protect the environment. Advanced pollution control technologies are needed to address these issues and keep WtE as a safe and effective solution.

WtE technologies offer a way to manage waste while meeting energy needs. They are an important part of waste management plans and a step toward using more renewable energy. As technology improves, WtE may become even more important in reducing landfill use and improving energy security.

History

Around 1000 BCE, people in Jerusalem burned waste openly. They used the ashes as fertilizer. As human settlements grew, burning waste became common to reduce waste volume and to control rats and disease. This practice was not used for energy production at that time.

In the late 19th century, the first attempts to create energy from burning waste began. The first incinerator, which did not work well, was built around 1870 in London. In 1874, a machine called the "Destructor" was built in Nottingham, UK, by Manlove, Alliott & Co. Ltd. This machine was designed by Alfred Fryer. The first incinerator in the United States was built in 1885 on Governors Island in New York, New York. In 1903, Denmark built its first waste-to-energy unit in Frederiksberg, Copenhagen. The first such facility in the Czech Republic was built in 1905 in Brno. These early incinerators did not control emissions, causing serious pollution in air, soil, and water from heavy metals, acid gases, and harmful chemicals.

By the 1970s, people became more aware of health and environmental protection. This led to a comprehensive approach to managing waste. Air pollution control systems were developed to reduce harmful emissions by more than 99%. Heat from these systems was used directly for heating or to produce electricity. Technologies to process leftover mixed solid waste have only recently become a major focus, driven by the need to improve energy recovery.

Methods

Incineration is a method of burning organic materials, such as waste, to produce energy. It is the most common way to convert waste into energy (WtE) in many countries. In OECD countries, all new incineration plants that burn waste (such as leftover household waste, commercial waste, industrial waste, or refuse-derived fuel) must follow strict rules to control harmful emissions. These rules apply to pollutants like nitrogen oxides (NOx), sulfur dioxide (SO2), heavy metals, and dioxins. Modern incineration plants are much different from older ones, which did not recover energy or materials. Today, incinerators can reduce the volume of waste by 95-96%, depending on the waste’s composition and how much material, like metals, is recovered from the ash for reuse.

Incinerators may release small amounts of fine particles, heavy metals, dioxins, and acid gases, but modern plants produce much lower emissions. Managing the leftover materials is also important. Toxic fly ash must be handled as hazardous waste, and incinerator bottom ash (IBA) must be reused properly. Some people argue that incinerators waste valuable resources and might discourage recycling. However, countries with high recycling rates (up to 70%) still use incineration to reduce landfill use.

Incinerators typically produce electricity with 14-28% efficiency. To use the remaining energy, it can be used for district heating, which increases overall efficiency to over 80%. Incineration is an older method of WtE generation. It involves burning waste to heat water, which powers steam generators to create electricity and heat for homes, businesses, and industries. A problem is that burning waste can release pollutants into the air, such as acidic gases that contributed to acid rain in the 1980s. Modern incinerators use advanced burn chambers and controlled burners to minimize emissions, reducing the need for some pollution control systems.

Lime scrubbers neutralize acids in smoke, preventing them from harming the environment. Other devices, like fabric filters and catalysts, capture or destroy other pollutants. According to the New York Times, modern incinerators are so clean that more dioxin is released from home fireplaces and barbecues than from incinerators. The German Environmental Ministry states that strict regulations have made incinerators no longer a major source of dioxin, dust, or heavy metal emissions.

Compared to other WtE methods, incineration is often preferred because it produces more electricity, costs less to build, and has lower emissions. It also reduces landfill waste effectively. Another method to convert waste into fuel is pyrolysis, which breaks down organic materials at high temperatures in an oxygen-free environment. Plastic waste is ground, melted, and pyrolyzed. Catalytic converters help in this process. The vapors are condensed into oil or fuel, stored, and filtered. The resulting fuel, called thermofuel or energy from plastic, can power vehicles and machinery.

A newer process uses two catalysts—cobalt and zeolite—to convert plastics like polyethylene and polypropylene into propane, with about 80% efficiency. Other emerging technologies produce energy from waste without direct burning. These methods can generate more electricity from the same fuel by separating harmful components (like ash) before processing, allowing higher combustion temperatures in boilers or engines. Some advanced systems convert waste into liquid or gaseous fuels using heat without oxygen, avoiding direct combustion. These technologies are often cleaner because unwanted materials are removed before treatment.

Thermal treatment technologies include:
– Gasification: produces combustible gas, hydrogen, and synthetic fuels.
– Thermal depolymerization: creates synthetic crude oil for further refining.
– Pyrolysis: produces bio-oil and char.
– Plasma arc gasification: generates syngas (hydrogen and carbon monoxide), usable fuel, and materials like glass-like silicates and metals.

Non-thermal technologies include:
– Anaerobic digestion: produces biogas rich in methane.
– Fermentation: creates fuels like ethanol, lactic acid, or hydrogen.
– Mechanical biological treatment (MBT): combines sorting and biological processes to create fuel or further treat waste.

Global developments

During the 2001–2007 period, waste-to-energy capacity grew by about four million metric tons per year.

Japan and China each built several plants using direct smelting or fluidized bed combustion of solid waste. In early 2016, China had about 434 waste-to-energy plants. Japan uses the most thermal treatment for municipal solid waste globally, processing 40 million tons annually.

Some newer plants use stoker technology, while others use advanced oxygen enrichment technology. Worldwide, several treatment plants use processes like direct smelting, the Ebara fluidization process, and the Thermoselect JFE gasification and melting technology.

As of June 2014, Indonesia had 93.5 MW of installed waste-to-energy capacity, with additional projects in different stages of planning totaling 373 MW.

India’s first waste-to-energy facility was built by Timarpur-Okhla Waste Management Company Pvt Ltd in Delhi in January 2012. It processes 2,000 tonnes of solid waste daily and generates 16 MW of renewable energy. India’s first IGBC platinum-rated net-zero Green Waste-to-Energy Campus, in Jamnagar, Gujarat, was established by Abellon Clean Energy and designed by INI Design Studio. It processes 220,000 tons of municipal solid waste yearly into 7.5 MW of clean energy. The facility requires little human interaction during processing and features a transparent design for educational purposes. It uses 20% of its land for the plant, with the remaining 80% dedicated to community activities.

In July 2008, the Biofuel Energy Corporation of Denver, Colorado, opened two biofuel plants in Wood River, Nebraska, and Fairmont, Minnesota. These plants used distillation to produce ethanol for vehicles and engines. Both plants were acquired by Green Plains in 2013. The Fairmont plant closed in 2025, while the Wood River plant operated at 99% capacity in Q2-2025.

Fulcrum BioEnergy, founded in 2007 in Pleasanton, California, built a waste-to-energy plant near Reno, Nevada, to produce sustainable aviation fuel (SAF). The plant, named Sierra BioFuels, was under construction from 2022 to May 2024. Fulcrum expected it to produce about 10.5 million gallons of Fischer-Tropsch products yearly from nearly 200,000 tons of municipal solid waste. Only 350 gallons of syncrude were exported to Marathon Petroleum’s refinery for jet fuel conversion. The plant faced issues, including damage from unexpected nitric acid and thick concrete-like deposits in its gasification system. In 2024, Fulcrum BioEnergy stopped operations after defaulting on $290 million in bonds issued by Nevada’s Department of Business and Industry to fund construction.

Waste-to-energy technology includes fermentation, which converts biomass into ethanol using waste from plants or organic materials. During fermentation, sugar in waste turns into carbon dioxide and alcohol, similar to the process used to make wine. Fermentation usually occurs without air.

Esterification, another process, produces biodiesel using waste-to-energy technologies. Its cost-effectiveness depends on the type of waste used and factors like transportation distance and oil content in the waste. Gasification and pyrolysis can achieve up to 75% thermal conversion efficiency (fuel to gas), though complete combustion is more efficient. Some pyrolysis processes require external heat, which can come from gasification, making the combined process self-sustaining.

Carbon dioxide emissions

In waste-to-energy (WtE) processes that use heat, most of the carbon in the waste becomes carbon dioxide (CO₂) in the air. This includes the final burning of materials made from pyrolysis and gasification, except when biochar is created for fertilizer. City garbage (MSW) has about the same amount of carbon as CO₂ itself (27%), so burning 1 metric ton (1.1 short tons) of MSW produces about 1 metric ton (1.1 short tons) of CO₂.

If the same amount of MSW were buried in a landfill instead, it would produce about 62 cubic meters (2,200 cubic feet) of methane. Methane comes from the breakdown of biodegradable waste without oxygen. Methane has more than twice the effect on global warming compared to the CO₂ that would be released if the waste were burned. In some countries, large amounts of landfill gas are collected, but some still escape into the air. For example, in the U.S. in 1999, methane emissions from landfills were about 32% higher than the CO₂ that would have been released through burning.

Most biodegradable waste is biomass, meaning it comes from living things like plants. These plants used atmospheric CO₂ in the past growing season. If these plants are regrown, the CO₂ released from burning them can be reabsorbed by new plants.

Because of this, many countries treat the biomass part of waste as renewable energy. The rest of the waste, such as plastics and products made from oil and gas, is usually considered non-renewable.

CO₂ emissions from burning plastic waste are higher than emissions from current fossil fuel power systems, even when using carbon capture and storage. Plastic waste used for energy is expected to grow greatly by 2050. To prevent global warming, carbon must be separated during energy recovery processes. Otherwise, efforts to reduce warming could fail due to plastic waste.

Most city garbage is biogenic, meaning it comes from biological sources, such as paper, cardboard, wood, cloth, and food scraps. Usually, half of the energy in MSW comes from biogenic materials. This energy is often recognized as renewable energy based on the waste used.

The European CEN 343 working group has developed methods to determine the biomass fraction in waste fuels, such as Refuse Derived Fuel/Solid Recovered Fuel. Early methods included manual sorting and selective dissolution. A detailed comparison of these methods was published in 2010. Because both methods had limitations, two new methods were created.

The first method uses radiocarbon dating, which measures carbon-14. A technical review (CEN/TR 15591:2007) and standard (CEN/TS 15747:2008) were published in 2007 and 2008. In the U.S., a similar method is covered by the standard ASTM D6866.

The second method, called the balance method, uses data on waste composition and plant operations to estimate biomass content using mathematical models. This method is currently used at three Austrian and eight Danish incinerators.

A comparison at three Swiss incinerators showed both methods gave the same results.

Carbon-14 dating can accurately determine the biomass fraction in waste and its energy value. Knowing the energy value is important for programs like the Renewable Obligation Certificate in the U.K., which gives certificates based on energy from biomass. Research, including a study by the U.K. Renewable Energy Association, has shown how Carbon-14 results can calculate biomass energy. In 2011, the U.K. energy authority Ofgem accepted Carbon-14 as a way to measure biomass energy in waste. Their Fuel Measurement and Sampling (FMS) guidelines explain the information they need for such proposals.

Physical location

A 2019 report requested by the Global Alliance for Incinerator Alternatives (GAIA) and completed by the Tishman Environment and Design Center at The New School found that 79% of the 73 waste-to-energy facilities operating in the U.S. at that time were located in low-income communities and/or communities with diverse racial backgrounds. This is because of past laws that separated neighborhoods based on race and wealth, which allowed wealthier, whiter areas to avoid having industrial facilities and to keep people of color out of their regions. In Chester, Pennsylvania, where a local group is fighting against a waste-to-energy facility, Sintana Vergara, an assistant professor in the Department of Environmental Resources Engineering at Humboldt State University in California, explained that people in the area are resisting the facility because of the pollution it causes and because these facilities are often placed in communities without asking for their opinions or providing any benefits to the people living there.

In other countries, waste-to-energy facilities are often placed near homes without causing major conflicts, even in wealthy areas. One example is Amager Bakke, a waste-to-energy facility in central Copenhagen, Denmark.

Notable examples

According to a 2019 United Nations Environment Programme report, there are 589 waste-to-energy (WtE) plants in Europe and 82 in the United States.

Examples of WtE plants include:
• Essex County Resource Recovery Facility, Newark, New Jersey
• Harrisburg incinerator, Harrisburg, Pennsylvania
• Lee County Solid Waste Resource Recovery Facility, Fort Myers, Florida, USA (1994)
• Montgomery County Resource Recovery Facility, Dickerson, Maryland, USA (1995)
• Spittelau (1971) and Flötzersteig (1963), Vienna, Austria (Wien Energie)
• SYSAV waste-to-energy plant in Malmö (2003 and 2008), Sweden
• Algonquin Power, Brampton, Ontario, Canada
• Stoke Incinerator, Stoke-on-Trent, UK (1989)
• Delaware Valley Resource Recovery Facility, Chester, United States
• Teesside EfW plant near Middlesbrough, North East England (1998)
• Edmonton Incinerator, Greater London, England (1974)
• Burnaby Waste-to-Energy Facility, Metro Vancouver, Canada (1988)
• Timarpur-Okhla Waste to Energy Plant, New Delhi, India
• East Delhi Waste Processing Company Limited, New Delhi, India
• SELCHP, South Bermondsey in Greater London, England (1994)

No industrial liquid fuel producing gasification plants are currently operational, but two are under construction in Varennes (Canada) and Swindon (United Kingdom).

The US Air Force once tested a Transportable Plasma Waste to Energy System (TPWES) facility (PyroGenesis technology) at Hurlburt Field, Florida. The plant, which cost $7.4 million to build, was closed and sold at a government auction in May 2013, less than three years after it was completed. The opening bid was $25. The winning bid was sealed.

In addition to large plants, smaller domestic waste-to-energy incinerators also exist. For example, the Refuge de Sarenne has a domestic waste-to-energy plant. It is made by combining a wood-fired gasification boiler with a Stirling motor.

Renergi will expand their system to convert waste organic materials into liquid fuels using a thermal treatment process in Collie, Western Australia. The system will process 1.5 tonnes of organic matter per hour. Each year, the facility will divert 4,000 tonnes of municipal waste from landfills and use an additional 8,000 tonnes of organic waste from agricultural and forestry operations. Renergi’s patented “grinding pyrolysis” process aims to convert organic materials into biochar, bio-gases, and bio-oil by applying heat in an environment with limited oxygen.

Another project in the Rockingham Industrial Zone, about 45 kilometers south of Perth, will build a 29 MW plant capable of powering 40,000 homes using 300,000 tonnes of municipal, industrial, and commercial waste annually. In addition to supplying electricity to the South West Interconnected System, 25 MW of the plant’s output has already been reserved through a power purchase agreement.

The Reppie waste-to-energy plant in Ethiopia was the first such plant in Africa. It became operational in 2018.