What does a tonne of CO2 equivalent (CO2e) represent?

Carbon dioxide or CO₂ doesn’t get good press, everyone talks about limiting it, eliminating it or even capturing it… In a word, nobody wants it (except the trees)! But if the ton of CO₂ is already a difficult concept to raise awareness, what about the tonne of carbon equivalent (or CO₂e) which remains a downright abstract concept for most of us.

Every year, human activities emit more than 50 billion tons of greenhouse gases, which increases the greenhouse effect and increases climate change.

CO emissions₂ are not linked only to industrial activities but also to our daily activities and therefore to our lifestyle. Each French person generates on average between 9 and 12 tonnes of CO₂e per year (according to sources).

But when we say that, what are we to understand by CO₂and ? This means that the estimate takes into account the CO₂ but also the other greenhouse gases emitted by a French person and in particular the two main ones, which are methane (CH₄) and the nitrous oxide (NOT₂O).

They are converted to carbon dioxide equivalent for simplicity. This makes it possible to have a single indicator for all greenhouse gases.

What are carbon equivalent and C02 equivalent (CO₂e)?

We know that there are several greenhouse gases, starting with water vapour. the carbon dioxide (CO₂) is the most common, but other gases, natural or artificial, have the same effect, with more or less marked actions.

CO₂ comes from combustion because everything that burns contains carbon (except hydrogen): gasoline, coal, gas, wood, etc. In the flame, carbon reacts with oxygen in the air to produce energy (heat) and CO₂.

1kg of methanea gas resulting from organic fermentations, acts in the atmosphere as the equivalent of 28 kg of CO₂and 1 kg of nitrous oxide as 298 kg of CO₂ !

All of the gases resulting from a manufacturing process are thus transformed and expressed in a single so-called equivalent unit. This quantitative measurement uses carbon dioxide as a reference. It’s a ” standard meter to assess not the length but the greenhouse effect. It is expressed in carbon dioxide equivalent (equivalent CO₂ or CO₂e).

Can you see the difference better? CO₂ is a gaseous compound and CO₂she is a measurement of the greenhouse effect. This makes it possible to assess the carbon footprint of individuals and that of each daily activity.

Be careful, however, not to confuse CO equivalent₂ and carbon equivalent which only considers the mass of carbon: one ton of CO₂ is equivalent to 12/44 tonnes of carbon (1 kg CO₂ = 0.27 kg C). In the ISO 14064 standard, the tonnes of CO₂.

An example to understand

The distinction between CO₂ and co₂It is easier to understand when we take a simple example.

The dairy cow is a ruminant whose digestion process generates methane, the most abundant greenhouse gas after carbon dioxide. So the greenhouse gas emissions of the cow cannot be expressed in CO₂ but must be in methane. She emits 70 kg per year.

To compare this value to the main greenhouse gas, carbon dioxide, we must transpose the value of 70 kg of methane into CO₂.

Different greenhouse gases have different lifetimes in the atmosphere. A multiplier is therefore applied to methane emissions, which is the global warming potential (or PRG), expressed by default over a period of 100 years (PRG100).

As seen in the table above, methane is 28 times more potent than CO₂ : so we multiply the 70 kg of methane by 28 to obtain an equivalent in CO₂ (CO₂e), i.e. 1960 kg of CO₂e.

Then, we can for example compare the 1960 kg of CO₂and emissions emitted by the cow to a journey in a small gasoline-powered car that emits only CO₂ (and no methane).

Thus, according to the manufacturer’s data, the Peugeot 208 emits an average of 104 g CO₂ per km, i.e. 104 kg per 1000 km. The annual greenhouse gas emissions of a dairy cow (1960 kg CO₂e) are comparable to 18,846 km traveled in a Peugeot 208. Surprising, isn’t it?

What is a ton of carbon equivalent (CO2e)?

If we insist that global warming does not exceed 2° Celsius, the average carbon footprint for an inhabitant of the planet should not not exceed more than 2.1 tonnes per year by 2050. There’s work to be done!

To get an idea of ​​what a ton of CO₂ represents (i.e. half of our ideal quota), here are some correspondences that have the merit of enlightening us.

A ton of CO₂and corresponds to:

• 500 m³ of gas (the heating of a moderately insulated 50 m² apartment) or 380 liters of fuel oil
• 1 round trip Paris-New York by plane
• 6 round trips Paris/Marseille by plane for one person (according to the civil aviation calculator)
• 190 round trips Paris-Bordeaux by train
• 14,000 km with a Twingo in town
• 4300 kWh of electricity
• 1.8 tons of paper
• 4,700 kilos of potatoes
• 8,800 cups of coffee;
• 1,200 kilos of bread
• 250 kg of beef

The more a person consumes (food, heating, travel, travel, electronics, textiles, etc.), the more CO they emit₂ and therefore carbon equivalent (CO2e).