Challenges facing the development of a credible sustainability assessment

Sustainability assessments of alternative powertrains are rarely clear-cut and often involve complex interplays between factors. These range from vehicle parameters and powertrain details, which manufacturers can broadly influence, to customer choices and usage patterns that are far harder to control and predict. We investigated some of the reasons for variations in assessments of vehicles, focusing on some of the additional parameters that affect parametric comparisons of battery electric vehicles (BEV), and the trade-offs many of these introduce. The production impacts of alternative vehicles such as BEVs were found to be potentially far more significant than those of current vehicles. Existing data for battery production was found to be highly variable and have the potential to significantly influence the overall results of whole life assessments. Some of the economic considerations of alternative vehicles are also highlighted. These show that, along with direct vehicle costs, taxation revenues, external costs and recycling profitability may also be affected. We conclude that in order to enhance whole life sustainability assessments, more research is required to better quantify, incorporate and appreciate many additional factors and the effects of various trade-offs.