Impact of the electricity mix and use profile in the life-cycle assessment of electric vehicles

Abstract

This paper presents an environmental and an economic Life-Cycle Assessment (LCA) for conventional and electric vehicle technologies, focusing mainly on the primary energy source and the vehicle operation phase Greenhouse Gas (GHG) emissions. A detailed analysis of the electricity mix was performed, based on the contribution of each type of primary energy source and their variation along a year. Three mixes were considered, with different life cycle GHG intensity: one mainly based in fossil sources, a second one with a large contribution from nuclear and a third one with a significant share of renewable energy sources. The conventional vehicle technology is represented by gasoline and diesel International Combustion Engine Vehicles (ICEVs), while the electric technology is represented by Plug-in Hybrid Electric Vehicles (PHEVs) and Battery Electric Vehicles (BEVs). Real world tests were performed for representative compact and sub-compact EVs. The use profile of the vehicle was based on data acquired by a real time data acquisition system installed in the vehicles. The results show that a mix with a large contribution from Renewable Energy Sources (RESs) does not always translate directly into low GHG emissions for EVs due to the high variability of these sources. The driving profile under different scenarios was also analyzed, showing that an aggressive style can increase the energy consumption by 47%. The tests also showed that the use of climate control can increase the energy consumption between 24 and 60%. Compared with other technologies, EVs can be more sustainable from an environmental and economic perspective; however, three main factors are required: improvement of battery technology, an eco-driving attitude and an environmental friendly electricity mix.