The amount of carbon dioxide a vehicle emits into the air is directly proportional to the amount of fuel it uses and the carbon content of the fuel.
Exhaust emissions, in particular carbon dioxide emissions, are one of the major issues of the day. Although it is quite a controversial and wide-ranging topic, the basic calculation of the amount of CO2 emitted by a vehicle is fairly straightforward. It all depends on fuel consumption and the amount of carbon contained in the fuel type.
Carbon dioxide (CO2) emissions are given in grams per kilometre travelled, all calculated from the combined consumption determined by the WLTP measurement cycle. A simplified calculation might read:
|the amount of carbon dioxide produced by burning 1 litre of fuel [g]
A full description of the calculation methodology can be found, for example, on the website of the US Environmental Protection Agency – EPA.
Calculation of CO2 emissions for a diesel engine:
1 litre of diesel weighs 835 grams and contains 86.2% carbon, which is equivalent to 720 grams of carbon in each litre of diesel. It takes 1920 grams of oxygen to burn 1 liter of diesel. The carbon dioxide produced is therefore equal to the sum of 720 grams of carbon and 1920 grams of oxygen. That’s 2640 grams of CO2 per litre of diesel burned.
Calculation of CO2 emissions for a petrol engine:
Calculation of CO2 emissions for LPG fuel:
Calculation of CO2 emissions for CNG drive in the High variant:
1 kilogram of CNG contains 72.7% carbon, which corresponds to 727 grams of carbon in each kilogram of CNG. It takes 1939 grams of oxygen to burn 1 kilogram of CNG. The carbon dioxide produced is therefore equal to the sum of 727 grams of carbon and 1939 grams of oxygen. That’s 2666 grams of CO2 from one kilogram of CNG burned.