WtE covers a variety of technologies that are used to convert waste left after recycling into electricity and heat. Although it is often used to refer to the combustion of residual municipal solid waste, any process that uses waste as a fuel to produce energy is included in the term.

A combustion-based WtE facility requires burning residual waste at high temperatures without adding any additional fuel, and under controlled conditions.  Emissions are cleaned before being released into the atmosphere to comply with strict air quality standards.  Heat is used to create steam from the combustion process, which drives a turbine to generate electricity.  Heat can also be recycled to provide low pressure steam, hot water, space heating or even refrigeration for use in industrial or domestic buildings.

References: What is energy from waste

Waste to Energy is more than just incineration.  An old-style incinerator's sole purpose was to dispose of unwanted materials by burning them.  A modern WtE via combustion facility is a power plant that produces electricity and heat using the thermal treatment process.  It extensively cleans up the combustion gases before emission to the atmosphere and involves post-combustion extraction of metals and reuse of ash.

Referemces: WtE Combustion

Waste-to-Energy (or waste-to-energy) facilities provide secure, technologically advanced waste disposal facilities that reduce greenhouse gas emissions, produce clean energy and recycle metals. As a technology that can help combat climate change, Waste-to-Energy (WTE) is widely known.

Referemces: Benefits

There will still be waste products that can not be viably recycled, even with the predicted increases in recycling rates.  Waste-to-Energy facilities do not have the technical ability to process all wastes into new products and not every potentially recyclable material has a reuse application.  Recycled materials can become so polluted that it is not possible to recover them economically or practically.

There are many examples of WtE operating alongside high levels of recycling. In Belgium, for instance, Flanders has a high degree of waste prevention, reuse and recycling, with about 25 percent of waste being used in WtE plants for energy generation.

Referemces: Relationship with recycling

Waste-to-Energy facilities are required to meet strict emissions standards.  All WtE facilities needs an Environmental Permit from the Environment Agency to operate.  The permit governs all activities and will be issued only if the Environment Agency is confident that the local community and the environment will not be adversely affected.

Referemces: Public health and the environment

Waste-to-energy facilities are equipped with sophisticated technology that monitor and track emissions.  Air pollution control technology is a major portion of the plant infrastructure.  The extent of 24 hour a day air emission control technology coupled with stringent environmental regulations means WtE facilities are designed and operated to have no significant impact on air quality or health.

As part of any Waste-to-Energy planning application, an Air Quality Assessment will be carried out to look at existing air quality, the potential impact of the facility and associated traffic on local air quality and any mitigation measures.

Referemces: Public health and the environment / Air quality

Dioxins and furans can be produced whenever something is burned, such as cigarettes, barbeques, garden bonfires, industrial furnaces or accidental fires. In a WtE facility, the burning of residual waste only makes a very small contribution to the current background dioxin levels in our atmosphere.  Data shows that the introduction of strict regulations for WtE facilities in the USA and the EU resulted in a decrease of over 99% in dioxin emissions relative to 1990 emissions.

Referemces: Public health and the environment / Dioxins and furans

Waste is treated with air extraction systems, filters and sound proofing to contain odors and noise inside an enclosed area.  No sorting or treatment of waste takes place in the open.  Odor is controlled by drawing air into the combustion process via the waste reception hall to ensure that the hall stays under negative pressure.  This prevents any odors from escaping outside the facility.

There is no scientific evidence reviewed to support this claim.  No study into the health of communities living near WtE (WtE) facilities has been able to demonstrate a conclusive link between emissions from an WtE facility and adverse effects on public health.

Referemces: DEFRA report / EfW and health

Waste-to-Energy facilities typically produces two types of solid by-products.  These are Incinerator Bottom Ash (IBA) and Air Pollution Control (APC) residues.  The IBA accounts for approximately 25% by weight of the waste. Recyclable materials, such as metals, are easily removed from IBA.  Normally, the remaining IBA is aged and stored. In civil engineering applications, it can then be used as an aggregate. The amount of APC residues produced is much smaller, usually about 4% of the facility's waste. APC residues are hazardous waste, mainly because they are highly alkaline due to high lime content. APC residues are disposed of in specialist hazardous waste facilities.

Referemces: Technologies / WtE via combustion

Burning waste in a WtE facility produces carbon dioxide, as with any combustion process.  However given the composition of the waste a significant proportion of the carbon dioxide is from biogenic sources rather than fossil fuels.

It is, therefore, estimated that for every tonne of waste combusted in modern WtE plants, over 460kg less of carbon dioxide equivalent is released into the air due to avoided methane from landfilling, fossil fuel power generation, and metals production.

Referemces: Assessment of the greenhouse effect impact of technologies used for energy recovery from municial waste

DEFRA's Waste and Resources Assessment Tool for the Environment (WRATE) can calculate the environmental impacts of different municipal waste management systems.  It uses life cycle assessment to include the resources used, waste transportation and operation of a whole range of waste management processes with their environmental costs and benefits.