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Emission factor
 
 
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An emission factor can be defined as the average emission rate of a given pollutant
Pollutant

A pollutant is a waste material that pollutes air, water or soil.Three factors determine the severity of a pollutant: its chemical nature, the concentration and the persistence....
 for a given source, relative to the intensity of a specific activity. Emission factors are used to derive estimates of air pollutant or greenhouse gas
Greenhouse gas

Greenhouse gases are gases in an atmosphere that Absorption and Emission radiation within the Infrared#Different regions in the infrared range....
 emissions based on the amount of fuel combusted
Combustion

Combustion or burning is a complex sequence of exothermic chemical reactions between a fuel and an oxidant accompanied by the production of heat or both heat and light in the form of either a glow or flames, appearance of light flickering....
, the number of animals in animal husbandry
Animal husbandry

Animal husbandry, also called animal science, stockbreeding or simple husbandry, is the agriculture practice of animal breeding and raising livestock....
, on industrial production levels, distances traveled or similar activity data.

Estimating emissions
Emission factors assume a linear relation between the intensity of the activity and the emission resulting from this activity:

Emissionpollutant = Activity * Emission Factorpollutant

The level of uncertainty of the resulting estimates depends significantly on the source category and the pollutant.






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Encyclopedia


An emission factor can be defined as the average emission rate of a given pollutant
Pollutant

A pollutant is a waste material that pollutes air, water or soil.Three factors determine the severity of a pollutant: its chemical nature, the concentration and the persistence....
 for a given source, relative to the intensity of a specific activity. Emission factors are used to derive estimates of air pollutant or greenhouse gas
Greenhouse gas

Greenhouse gases are gases in an atmosphere that Absorption and Emission radiation within the Infrared#Different regions in the infrared range....
 emissions based on the amount of fuel combusted
Combustion

Combustion or burning is a complex sequence of exothermic chemical reactions between a fuel and an oxidant accompanied by the production of heat or both heat and light in the form of either a glow or flames, appearance of light flickering....
, the number of animals in animal husbandry
Animal husbandry

Animal husbandry, also called animal science, stockbreeding or simple husbandry, is the agriculture practice of animal breeding and raising livestock....
, on industrial production levels, distances traveled or similar activity data.

Estimating emissions


Emission factors assume a linear relation between the intensity of the activity and the emission resulting from this activity:

Emissionpollutant = Activity * Emission Factorpollutant

The level of uncertainty of the resulting estimates depends significantly on the source category and the pollutant. Some examples:
  • Carbon dioxide
    Carbon dioxide

    Carbon dioxide is a chemical compound composed of two oxygen atoms covalent bond to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state....
     (CO2) emissions from the combustion of fuel can be estimated with a high degree of certainty regardless of how the fuel is used as these emissions depend almost exclusively on the carbon
    Carbon

    Carbon is a chemical element with chemical symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalence?making four electrons available to form covalent bond chemical bonds....
     content of the fuel, which is generally known with a high degree of precision. The same is true for sulphur dioxide (SO2), since also sulphur contents of fuels are generally well known. Both carbon and sulphur are almost completey oxidized during combustion and all carbon and sulphur atoms in the fuel will be present in the flue gas
    Flue gas

    Flue gas is gas that exits to the atmosphere via a flue, which is a pipe or channel for conveying exhaust gases from a fireplace, oven, furnace, boiler or steam generator....
    es as CO2 and SO2 respectively.
  • In contrast, the levels of other air pollutants and non-CO2 greenhouse gas emissions from combustion depend on the precise technology applied when fuel is combusted. These emisisons are basically caused by either incomplete combustion of a small fraction of the fuel (carbon monoxide
    Carbon monoxide

    Carbon monoxide, with the chemical formula CO, is a colorless and odorless, tasteless, yet highly toxic gas. Its molecules consist of one carbon atom covalent bond to one oxygen atom....
    , methane
    Methane

    Methane is a chemical compound with the molecular formula . It is the simplest alkane, and the principal component of natural gas. Methane's bond angles are 109.5 degrees....
    , non-methane volatile organic compounds
    NMVOC

    NMVOC is the abbreviation for non-methane volatile organic compounds.It is a generic term for a large variety of chemically different compounds, like for example, benzene, ethanol, formaldehyde, cyclohexane, 1,1,1-Trichloroethane or acetone....
    ) or by complicated chemical and physical processes during the combustion and in the smoke stack or tailpipe. Examples of these are particulates, NOx, a mixture of nitric oxide
    Nitric oxide

    Nitric oxide or nitrogen monoxide is a chemical compound with chemical formula NitrogenOxygen. This gas is an important signaling molecule in the body of mammals, including humans, and is an extremely important intermediate in the chemical industry....
    , NO, and nitrogen dioxide
    Nitrogen dioxide

    Nitrogen dioxide is the chemical compound with the chemical formula NitrogenOxygen2. One of several nitrogen oxides, NO2 is an intermediate in the industrial synthesis of nitric acid, millions of tons of which are produced each year....
    , NO2).
  • Nitrous oxide
    Nitrous oxide

    Nitrous oxide, commonly known as "laughing gas", is a chemical compound with the chemical formula Nitrogen2Oxygen. At room temperature, it is a colorless Flammability gas, with a pleasant, slightly sweet odor and taste....
     (N2O) emissions from agricultural soils are highly uncertain because they depend very much on both the exact conditions of the soil, the application of fertilizers and meteorological
    Meteorology

    Meteorology is the interdisciplinary scientific study of the Earth's atmosphere that focuses on weather processes and forecasting . Studies in the field stretch back millennia, though significant progress in meteorology did not occur until the eighteenth century....
     conditions.


Emission Factors for Greenhouse Gas Inventory Reporting


One of the most important uses of emission factors is for the reporting of national greenhouse gas inventories
Greenhouse gas inventory

Greenhouse gas inventories are a type of emission inventory that are developed for a variety of reasons. Scientists use inventories of natural and anthropogenic emissions as tools when developing atmospheric models....
 under the United Nations Framework Convention on Climate Change
United Nations Framework Convention on Climate Change

The United Nations Framework Convention on Climate Change is an international environmental treaty produced at the United Nations Conference on Environment and Development , informally known as the Earth Summit, held in Rio de Janeiro from 3 to 14 June 1992....
 (UNFCCC). The so-called Annex I Parties
United Nations Framework Convention on Climate Change

The United Nations Framework Convention on Climate Change is an international environmental treaty produced at the United Nations Conference on Environment and Development , informally known as the Earth Summit, held in Rio de Janeiro from 3 to 14 June 1992....
 to the UNFCCC have to annually report their national total emissions of greenhouse gases in a formalized reporting format, defining the source categories and fuels that must be included.

UNFCCC has accepted the Revised 1996 IPCC Guidelines for National Greenhouse Gas Inventories, developed and published by the Intergovernmental Panel on Climate Change
Intergovernmental Panel on Climate Change

The Intergovernmental Panel on Climate Change is a scientific intergovernmental body tasked to risk management of climate change caused by human activity....
 (IPCC) as the emission estimation methods that must be used by the parties to the convention to ensure transparency, completeness, consistency, comparability and accuracy of the national greenhouse gas inventories. These IPCC Guidelines are the primary source for default emission factors. Recently IPCC has published the 2006 IPCC Guidelines for National Greenhouse Gas Inventories. These and many more greenhouse gas emission factors can be found on IPCC's Emission Factor Database.

Particularly for non-CO2 emissions, there is often a high degree of uncertainty associated with these emission factors when applied to individual countries. In general, the use of country-specific emission factors would provide more accurate estimates of emissions than the use of the default emission factors. According to the IPCC, if an activity is a major source of emissions for a country ('key source'), it is 'good practice' to develop a country-specific emission factor for that activity.

Emission Factors for Air Pollutant Inventory Reporting

National Air Pollution Emission Inventories are required annually under the provisions of the UNECE Convention on Long-Range Transboundary Air Pollution
Convention on Long-Range Transboundary Air Pollution

The Convention on Long-Range Transboundary Air Pollution, often abbreviated as Air Pollution or CLRTAP, is intended to protect the human environment against air pollution and to gradually reduce and prevent air pollution, including long-range transboundary air pollution....
 (LRTAP). Emission estimation methods and the associated emission factors for air pollutants have been developed by the Task Force on Emission Inventories and Projections () and are published in the .

Sources of emission factors


Greenhouse gases

  • .
  • .
  • .

    Air Pollutants

    • US Environmental Protection Agency
    • .
    • .


    See also

    • Emission inventory
      Emission inventory

      An emission inventory is an accounting of the amount of pollutants discharged into the atmosphere. An emission inventory usually contains the total emissions for one or more specirfic greenhouse gases or air pollutants, originating from all source categories in a certain geographical area and within a specified time span, usually a specific y...
    • Air pollution
      Air pollution

      Air pollution is the introduction of chemicals, particulate matter, or biological materials that cause harm or discomfort to humans or other living organisms, or damages the natural environment, into the Earth's atmosphere....
    • AP 42 Compilation of Air Pollutant Emission Factors
      AP 42 Compilation of Air Pollutant Emission Factors

      The AP 42 Compilation of Air Pollutant Emission Factors, was first published by the U.S. Public Health Service in 1968. In 1972, it was revised and issued as the second edition by the U.S....
    • .
    • Emission standard
      Emission standard

      Emissions standards are requirements that set specific limits to the amount of pollutants that can be released into the environment. Many emissions standards focus on regulating pollutants released by automobiles and other powered vehicles but they can also regulate emissions from industry, power plants, small equipment such as lawn mowers...
    • Greenhouse gas
      Greenhouse gas

      Greenhouse gases are gases in an atmosphere that Absorption and Emission radiation within the Infrared#Different regions in the infrared range....
       and Greenhouse effect
      Greenhouse effect

      The greenhouse effect refers to the change in the steady state temperature of a planet or moon by the presence of an atmosphere containing gas that absorbs and emits infrared....
    • IPCC list of greenhouse gases
      IPCC list of greenhouse gases

      This is a list of anthropogenic greenhouse gases as used by the IPCC TAR....
    • Mobile Emission Reduction Credit (MERC)
      Mobile Emission Reduction Credit (MERC)

      A Mobile Emission Reduction Credit is an emissions trading generated within the transportation sector. The term ?Mobile Sources? refers to motor vehicles, engines, and equipment that move, or can be moved, from place to place....
    • Radiative forcing
      Radiative forcing

      In climate science, radiative forcing is defined as the change in net irradiance at the tropopause. "Net irradiance" is the difference between the incoming radiation energy and the outgoing radiation energy in a given climate system and is thus measured in Watts per square meter....