The calculation of the country mix of electricity in leading LCI databases: “top down”
People might think that the country mix of electricity is calculated by adding up all local LCIs: i.e. adding up all monitored emissions of all individual electrical power plants, in a country, as they are reported by the power plants and checked by the governments. However, this “bottom-up” approach was not doable in the past. Hence, the excising leading databases (Ecoinvent, Gabi (PEF), ELCD) apply an approach where the emissions are calculated from the electricity output . We call that “top down”.
The starting point of the standard “top down” calculations is the electrical power mix production of a country (the percentage of coal, oil, gas, nuclear, wind, solar, hydro, and other renewables). From these production mix data, the emissions are calculated for each type of energy source. The country specific data are derived by parameterization.
Unfortunately it is not possible establish which database is the most accurate, since these main leading databases are not very transparent in their calculations. Ecoinvent data seem to be the most advanced (Dones et al 2007), based on 12 European countries, and further parameterization. However, the ‘most advanced’ is not also the ‘most accurate’, since complexity is not related to accuracy. See for more detailed information on database comparisons (Olindo et al 2020, section3.1 and 3.2).