➗Emissions Factors
Emissions factors are used to estimate, calculate, or convert the rate an activity releases greenhouse gases (GHG) into the atmosphere.
Emissions factors are also called conversion factors, emission intensity, carbon intensity, or abbreviated as "EF". They are typically expressed as an amount of a pollutant emitted per unit of activity, such as kilograms (kg) of CO2 generated per kilowatt hour (kWh) of electricity purchased from your utility provider.
The United States Environmental Protection Agency (EPA), which publishes a library of U.S. emissions factors, defines an emissions factor as:
"A representative value that attempts to relate the quantity of a pollutant released to the atmosphere with an activity associated with the release of that pollutant"
Here are some examples of real emission factors:
The emission factor for coal-fired power generation is about 0.85 kilograms of CO2 per kilowatt-hour of electricity generated
The emission factor for gasoline-powered vehicles is about 200 grams of CO2 per kilometer driven
The emission factor for cattle farming is about 16 kilograms of CO2 per kilogram of beef
For example, if a power plant generates 100 megawatt-hours (MWh) of electricity per day, and the emission factor for coal-fired power generation is 0.85 kilograms of CO2 per kilowatt-hour, then the plant will emit 85,000 kilograms of CO2 per day (100 * 1,000 * 0.85).
There are a variety of emission factors available for different countries, activities, processes, transactions, and investments. These factors are typically developed by government agencies, research institutions, scientific studies, or lifecycle assessments (LCAs), and are based on a variety of data sources, such as emissions measurements, fuel consumption data, and engineering models.
See our full article on emissions factors here.
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