CO2-equivalent

CO2-equivalent (carbon dioxide equivalent, CDE, CO2e) — This is a conventional unit that is used to estimate the volume of greenhouse gas emissions (including to calculate the carbon footprint). It is measured in tons and indicates how much carbon dioxide is equal to the total volume of emissions, based on their impact on the climate.

Why do we need CO2-equivalent?

Climate scientists introduced this unit in the late 1980s to make it easier to estimate greenhouse gas emissions. The fact is that there are many greenhouse gases, and they all have different greenhouse activity - and, accordingly, contribute to climate change to varying degrees. Therefore, we calculate the total volume of steel emissions through comparable volumes of carbon dioxide - it has the least greenhouse activity. For example, over 100 years, one ton of methane retains as much heat in the atmosphere as 25 tons of CO2, and a ton of nitrous oxide (N2O) is equivalent in this regard to 298 tons of CO2.

How is CO2-equivalent calculated?

The greenhouse activity of compounds is expressed through so-called “global warming potentials” (GWP): special coefficients calculated for each gas based on the ability of its molecules to trap solar radiation. The GWP of CO2 is set to 1.

Carbon dioxide:  chemical formula CO2, lifetime in the atmosphere: GWP varies, over a 100-year time horizon: 1

Methane: chemical formula CH4, lifetime in the atmosphere: 12 years GWP, on a time horizon of 100 years: 25

Nitrous oxide: chemical formula N2O, lifetime in the atmosphere: 114 years GWP, on a time horizon of 100 years: 298

Trifluoromethane (HFC-23): chemical formula CHF3 , lifetime in the atmosphere: 270 years GWP, on a 100-year time horizon: 14,800

Chlorotrifluoromethane (CFC-13): chemical formula CClF3,lifetime in the atmosphere: 640 years GWP, on a 100-year time horizon: 14,400

Sulfur hexafluoride: chemical formula SF6, lifetime in the atmosphere: 3,200 years GWP, on a time horizon of 100 years: 22,800.

To calculate the volume of CO2-equivalent, the volume of each gas individually is multiplied by its GWP. This value is usually taken on a horizon of 100 years (unless otherwise indicated). That is, if 10 tons of methane and 3 tons of nitrous oxide were emitted, the CO2 equivalent of such emissions would be equal to (10 × 25) + (3 × 298) = 1,144 tons

European Union Emissions Trading System (EU ETS)

•Municipal waste incineration is currently excluded from the European Emissions Trading System (EU ETS). If the incineration method is included, waste treatment companies will have to buy emissions credits for every ton of CO2 they emit when processing household, corporate and industrial waste.
• The EU emissions trading system follows a cap and trade model, where one permit allows a plant to emit 1 tonne of CO2 (tCO2). In accordance with this scheme, a maximum is established for the total amount of greenhouse gases that can be emitted by all operating installations of the enterprise. EU emissions credits are then auctioned or allocated free of charge and can then be traded. Businesses must track and report CO2 emissions, ensuring they hand over enough allowances to authorities to cover their emissions. To exceed the emissions quota, a company must buy allowances from others. Conversely, if a facility emits less than allowed, it can sell the remaining credits. This allows the system to find the most cost-effective ways to reduce emissions without significant government intervention.

https://zerowasteeurope.eu/library/waste-incineration-under-the-eu-ets-an-assessment-of-climate-benefits/

https://en.wikipedia.org/wiki/European_Union_Emissions_Trading_System