Transportation CO2 Emissions in Automotive Life Cycle Assessments of Electric Vehicles - a Systems Theory Evaluation

Abstract

Electric vehicles are widely viewed as having the potential to reduce global carbon emissions because they effectively produce no carbon emissions to operate when powered by a low carbon electric energy source for charging their batteries. Given that transportation activities account for around a quarter of global carbon emissions, a societal switch to electric vehicles appears to offer significant potential in reducing global carbon emissions as most transport emissions are caused by internal combustion engines which burn fossil fuels. However, when viewed from an overall systems perspective (i.e. the entire “cradle to grave” life cycle of an electric vehicle – spanning from raw materials mining and extraction to final disposal and recycling) it transpires that significantly more carbon emissions are generated in order to manufacture electric vehicles, compared to traditional internal combustion engine vehicles. Taken over the whole life cycle of the vehicle, it can be several years of operation before the anticipated lower carbon emissions of electric vehicles are realised. Indeed, in some countries which rely on fossil fuel electric power generation, a traditional internal combustion engine vehicle produces lower carbon emissions over its life cycle. Significant research has already been conducted by others on the whole life-cycle carbon emissions of both electric vehicles and internal combustion engine vehicles. However, within that research, there has been no visible scrutiny of the CO2 emissions arising from the logistics transportation activities which are needed in order to produce these vehicles. This apparent omission in the existing research is surprising considering that transportation carbon emissions account for such a large proportion of global carbon emissions. Thus, there is a risk – if these transportation emissions are significant – that the anticipated environmental benefits of electric vehicles may be less than thought. Addressing this gap in the literature, this research examines, calculates and compares the carbon emissions arising from transportation activities in electric vehicle supply chains, comparing them with internal combustion engine vehicle supply chains and thereby provides an original contribution to knowledge. This was done via a case study simulation of supply chains of vehicle production in Germany for both types of vehicle, spanning from raw materials extraction to the completed vehicle manufacture. A proxy model of supply chains of vehicle materials was developed specifically for this research. It was found that electric vehicle supply chains give rise to 72% more carbon emissions in their transportation activities than equivalent internal combustion engine vehicles. Notwithstanding this, these emissions remain modest compared to carbon emissions in the rest of the vehicle life cycles and it was calculated that including these emissions in life cycle calculations typically delays the anticipated environmental benefits of electric vehicles by a mere few months of typical usage. Moreover, in the case of internal combustion engine vehicles this figure remains insignificant compared to the carbon emissions produced by years of burning fossil fuels during their usage phase, justifying this omission from the historical research literature. In the case of electric vehicles though – where these emissions during the usage phase are potentially eliminated – these emissions become comparable in size to their end of life and recycling emissions, and are around half the magnitude of the manufacturing emissions (both of which typically are considered in electric vehicle life cycle assessments). Thus, this research demonstrates that the impact of supply chain transportation emissions can no longer be omitted in the life cycle assessment literature. This is of specific importance to the wider research body in electric vehicle emissions, and thus relevant to academics, consultants and researchers who engage in this area of work.