Carbon equivalent: what is it?
Understand what the term "carbon equivalent" means and what it is for
Equivalent carbon is a concept that emerged to represent all greenhouse gases in a single unit, in order to make the carbon market viable.
Carbon credit corresponds to one ton of CO2. In the carbon market, a carbon credit is “earned” for each ton of CO2 that is absorbed or no longer emitted. Each of the carbon credits can be traded internationally. Once emissions are reduced, a country can obtain Certificates of Reduced Emissions (CERs), which are provided by bodies of the United Nations Framework Convention on Climate Change. Learn more about carbon credits in the article: "Carbon credits: what are they?".
But what about the other gases? Other gases such as methane (CH4), nitrous oxide (N2O), ozone (O3) and chlorofluorocarbons (CFCs) are also included in the bill. But for the emissions to be quantified for conversion into carbon credits, it was necessary to create a way to relate the gases so that they were all represented by the same unit, so the term "carbon equivalent" was created.
equivalent carbon
"Equivalent", according to dictionaries, expresses something that has the same meaning; equal value, and which can be substituted for having the same meaning.
Thus, the term "carbon equivalent" (also used in the area of metallurgy) is nothing more than the representation of other greenhouse gases (GHGs) in the form of CO2. It is to make them equal to CO2. Confused? Calm down, it's not as difficult as it sounds.
In order to have this conversion of other gases into CO2, the Global Warming Potential must be known (Global Warming Potential - GWP, the acronym in English). The GWP of greenhouse gases is related to the ability of each of them to absorb heat in the atmosphere (radiative efficiency) in a given time (usually 100 years), compared to the same heat absorption capacity of CO2. Thus, the formula for calculating carbon equivalent is multiplying the quantity of a gas by its GWP.
The GHG Protocol website provides tables with the GWP for each greenhouse gas. Consulting the table it is possible to find the carbon equivalent for each type of greenhouse gas other than CO2. To learn more about the greenhouse effect, take a look at the article: "What is the greenhouse effect?".
The application of calculations in order to find the equivalent carbon is useful when one intends to deal with greenhouse gases in a generalized way, as for example in this study carried out by the State University of Campinas (Unicamp), which compared the equivalent carbon emitted by cars electric and by combustion cars.
