CAV technology has the potential to make significant contributions to the decarbonisation of transport. However, there is a risk of negative environmental consequences if deployment and policy interventions are not carefully considered. The deployment of CAVs is likely to make significant changes to the carbon emissions associated with both the passenger and freight vehicle fleets. To meet the UK’s 2050 Net Zero target, the decarbonisation of road transport is imperative. At this time, it is unclear whether the overall impact of CAV deployment on the UK’s total carbon emissions will be positive or negative. There are many assumptions which have to be made when forecasting the total carbon impact of CAV deployment, but acknowledges that there may be opportunities to accelerate this. Based on a review of existing literature, this report makes the reasonable assumption that Level 4 passenger vehicles will be battery electric by default. This report explores some of the main mechanisms through which CAVs may impact the sustainability of road transport and how they may positively or negatively affect carbon emissions. It assumes that the transition to zero emission vehicles and the decarbonisation of the UK’s energy mix are largely unaffected by CAV deployment.
The CAV mechanisms established from existing literature have been categorised into five fundamental factors: number of vehicles manufactured, emissions per vehicle manufactured, total vehicle miles travelled, well/windmill-wheel emissions per vehicle mile travelled, and embedded emissions in infrastructure. An increase in any of these fundamental factors will increase the carbon emissions directly associated with CAV technology; however some mechanisms can be linked to multiple fundamental factors, sometimes with contradicting impacts. As such, the sensitivity of each mechanism and fundamental factor needs to be explored in more detail.