The role of electric vehicles in near-term mitigation pathways and achieving the UK's carbon budget

摘要

The decarbonisation of the road transport sector is increasingly seen as a necessary component to meet global and national targets as specified in the Paris Agreement. It may be achieved best by shifting from Internal Combustion Engine (ICE) cars to Electric Vehicles (EVs). However, the transition to a low carbon mode of transport will not be instantaneous and any policy or technological change implemented now will take years to have the desired effect. Within this paper we show how on-road emission factors of EVs and models of embedded CO2 in the vehicle production may be combined with statistics for vehicle uptake/replacement to forecast future transport emissions. We demonstrate that EVs, when compared to an efficient ICE, provide few benefits in terms of CO2 mitigation until 2030. However, between 2030 and 2050, predicted CO2 savings under the different EV uptake and decarbonisation scenarios begin to diverge with larger CO2 savings seen for the accelerated EV uptake. This work shows that simply focusing on on-road emissions is insufficient to model the future CO2 impact of transport. Instead a more complete production calculation must be combined with an EV uptake model. Using this extended model, our scenarios show how the lack of difference between a Business as Usual and accelerated EV uptake scenario can be explained by the time-lag in cause and effect between policy changes and the desired change in the vehicle fleet. Our work reveals that current UK policy is unlikely to achieve the desired reduction in transport-based CO2 by 2030. If embedded CO2 is included as part of the transport emissions sector, then all possible UK EV scenarios will miss the reduction target for 2050 unless this is combined with intense decarbonisation (80% of 1990 levels) of the UK electricity grid. This result highlights that whilst EVs offer an important contribution to decarbonisation in the transport sector it will be necessary to look at other transport mitigation strategies, such as modal shift to public transit, car sharing and demand management, to achieve both near-term and long-term mitigation targets.