A score is made with the steps taken into account for the calculation.
1.It is initially determined what type of fuel is used by the combustion vehicle replaced or to be replaced. The two main alternatives are Gasoline (naphtha) and Gasoil.
2. The performance (consumption in kilometers per liter) of the combustion vehicle replaced or to be replaced is determined. This is obtained from the survey of uses, consumption and yields of the transport sector of the DNE, see here.
3. The corresponding conversion factors (FC) are taken for each fuel provided by the National Energy Directorate of MIEM in the National Energy Balance that is carried out every year. The conversion factors allow to go from units of fuel volume (liters (l), cubic meter (m3), etc.) to energy units (tonne of oil equivalent (toe), joule (J), etc.), this is to determine how much energy is contained in a given volume of fuel. See here.
4.The emission factor (EF) of fuel is determined, which corresponds to the CO2 emitted by it when completely oxidized (consumed by combustion), using values ​​provided by the 2006 IPCC Guidelines for national inventories of greenhouse gases. The IPCC is the Intergovernmental Panel on Climate Change. See here the guide used: the values ​​are found in table 3.2.1 on page 3.16.
5. Finally, by means of a mathematical calculation, the emissions associated with the fuel are determined, achieving a value of kilograms (kg) of CO2 emitted per kilometer (km) traveled. Below is the mathematical formula used and a calculated example for a gasoline vehicle with a performance of 11 km / l and a diesel vehicle with a performance of 13 km / l. In addition, a conversion constant is used between the units of energy tera-joule (TJ) and kilo-tep (ktoe).
6. Regarding the CO2 emissions of the electric vehicle, it is important to note that it does not have emissions generated by the vehicle itself, but rather it would be possible to associate the emissions generated by the country’s electricity production, which is used to recharge the electric vehicles battery. Given that the electricity generation matrix in Uruguay has a renewable component close to 100%, the emissions associated with the generation of electricity are quite low. It is possible to access the historical emission factor (FE) of the National Interconnected System (SIN) through the following link. In 2019, the emission factor of the electricity grid was 13 tons CO2 / GWh. Additionally, in case of considering the CO2 emission associated with the generation of electricity, it would be necessary to associate the CO2 emissions from the extraction, transportation of crude oil, manufacturing and distribution of the considered fossil fuels (gasoline and diesel).