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MPhil in Engineering for Sustainable Development

global challenges, engineering solutions

Studying at Cambridge


Dennis Khah Kok Hong

Transitioning to Sustainable Transport and Achieving Carbon Budgets in the UK

The UK is projected to exceed the caps of the fourth and fifth carbon budgets according to the projections made by the UK Department of Business, Energy and Industrial Strategy, based on the previous carbon target of reducing greenhouse gas (GHG) emissions by 80% relative to 1990 levels by 2050. Markedly, in 2018, the transport sector, which accounts for 33% of total carbon emissions in the UK, only achieved a 3.2% reduction in the GHG emissions level relative to 1990 levels. The unsatisfactory performance from the transport sector became a greater cause for concern when the UK revised and legislated a more ambitious carbon target of achieving net-zero emissions by 2050 in June 2019. This would require all sectors within the UK to adopt a higher degree of transformation in their strategies and policies to keep up with the revised carbon target. With the continuation of the current transport policies and slow-moving pace of climate action, the GHG emissions level in the UK transport sector is likely to obstruct the overall progress of the UK in meeting its carbon target by 2050. A key strategy to reduce GHG emissions adopted by the UK Department of Transport beginning in 2010 is to transition conventional Internal Combustion Engine Vehicles (ICEVs) in the UK into an Electric Vehicle (EV) fleet.

However, it is uncertain whether the current pace of EV transition is sufficient to meet the carbon targets set by 2050. Furthermore, the transition to Plug-In Hybrid Electric Vehicles (PHEVs) from ICEVs does not guarantee GHG emissions reduction, as PHEV users have the option to operate in gasoline mode depending on various factors. Current research relating to the pace of the EV transition and EV user driving behaviour primarily focuses on utility grid and charging infrastructure planning and does not examine how these factors would impact performance in reducing GHG emissions. Therefore, this dissertation aims to analyse how the pace of transition to Battery Electric Vehicles (BEVs) and the driving behaviour of PHEV users can impact the GHG emissions reduction performance of the UK transport sector through 2050. A mathematical equation is proposed and relevant projections through regression analysis are used to calculate the GHG emissions performance of the UK car population from the present through 2050. Scenario-based models are then developed to analyse how varying the two factors would impact GHG emissions reduction performance. Comparison against the forecasted carbon budget highlighted that the current pace of BEV adoption is insufficient for the UK transport sector to achieve the fourth to seventh carbon budgets, due to the slow reduction in ICEVs. For the eighth and final carbon budgets, GHG emissions may still exceed the carbon budget despite the transition to EVs if PHEV users continue to drive in gasoline modes. The proposed model will serve as a useful reference to assess whether the current UK transport strategies and policies suffice and whether more actions are necessary to meet the 2050 carbon target.