The averaging bias - A standard miscalculation, which extensively underestimates real CO2 emissions

Abstract

The substitution of energy based on fossil fuels in different sectors like household or traffic by electric energy saves CO2 of this specific sector due to decreased fossil fuel consumption. An important quantity is the additional CO2 emission (Formula presented.) due to an increased electric power demand (Formula presented.) for the average electricity power demand (Formula presented.). Commonly, the formula (Formula presented.) is used (called simplified formula), where (Formula presented.) represents mean average CO2 footprint. It is shown in the present manuscript, that the simplified formula may underestimate the CO2 footprint significantly if the average CO2 footprint depends on the average electricity power demand, which is the case for most of mixed partly renewable and partly non-renewable electric energy systems. Therefore, the real CO2 emissions would outmatch those according to simplified easily by factor 2 in reality depending on the status of the electricity system. In order to establish a more precise calculation of the CO2 footprint, the general formula (Formula presented.) which is exact and contains the simplified formula as a special case, is derived in this article. The simplified formula requires an additional term that takes into account the change of the mean average CO2 footprint (Formula presented.) depending on the electricity power demand.