Decarbonising UK transport

High speed train at the railway station at sunset, photo by den-belitsky/Adobe Stock

den-belitsky/Adobe Stock

To inform the UK Government’s 2021 Transport Decarbonisation Plan, this research sets out a series of seven roadmaps for decarbonising domestic transport in the UK. These roadmaps address: cars and light goods vehicles; buses; coaches; heavy goods vehicles; rail; domestic shipping; and domestic aviation.

What is the issue?

In June 2019 the UK government committed to a net-zero contribution to global greenhouse gas emissions by 2050. Net zero refers to when the amount of carbon emissions produced are cancelled out by the amount removed and a balance is achieved.

Direct (tailpipe) emissions from domestic transport represent over a quarter of UK greenhouse gas emissions, making it the largest single source, 99 per cent of which is comprised of carbon dioxide (CO2).

To help prepare its 2021 Transport Decarbonisation Plan (TDP) the UK government needed to understand what research and innovation investment was needed to provide – in the near and medium term – to develop technologies to help deliver a decarbonised transport system by 2050.

How did we help?

To support the development of the TDP, the Department for Transport (DfT) commissioned RAND Europe, along with lead partners Mott MacDonald, SYSTRA, the University of the West of England and the School of International Futures, to examine technological solutions for reducing and removing CO2 at point of use across all modes for domestic transport.

This began with an extensive review of literature to examine and develop a synthesis of understanding concerning the progress and potential of different technology solutions for decarbonising transport across different modes.

A roadmapping exercise then followed in which a set of seven decarbonising roadmaps addressing different modes of transport – cars and light goods vehicles; buses; coaches; heavy goods vehicles; rail; domestic shipping; and domestic aviation – was evolved in conjunction with engagement with policymakers and experts.

What did we find?

  • There is a mix of solutions for decarbonising transport by 2050, the principal – which represents 91 per cent of direct emissions from domestic transport – being electrification with electric motors driven from either a battery or hydrogen fuel cell with a potential supporting role from route electrification.
  • The extent of decarbonisation achievable by 2050 could be as follows for the different modes:
    • cars and light goods vehicles (full removal of direct emissions achievable);
    • buses (full removal of direct emissions achievable);
    • coaches (near full, if not full, removal of direct emissions achievable);
    • rail (near-full removal of direct emissions achievable);
    • heavy goods vehicles (near full, if not full, removal of direct emissions achievable);
    • shipping (significant removal of direct emissions achievable); and
    • aviation (partial removal of direct emissions achievable).
  • Battery technology is a key solution for the removal of tailpipe emissions (especially for road transport) and is further ahead of other technologies such as hydrogen propulsion in terms of market readiness and adoption.
  • Hydrogen offers a form of on-board energy storage with no direct CO2 emissions in use and while it is not the dominant solution across the transport sector, it could have some significance for particular use cases within and across modes.
  • Fleet turnover will determine the pace for decarbonisation as decarbonising the vehicle fleet involves some shorter-term retrofit or changes to fuel mix but principally concerns replacing, over time, vehicles that produce emissions with those that do not.
  • To achieve decarbonisation by 2050 there is a pressing need for infrastructure solutions to be further developed and better understood, followed by prioritisation of solutions and scaling up of these solutions across the country.
  • Urgent short-term research and innovation interventions are a priority for the earlier part of the 30-year period ahead across all the roadmaps.

What can be done?

The roadmapping study and resulting report help to provide a whole-sector view of the challenges, opportunities and requirements facing transport, and the key actors and agents of change, on the road to decarbonisation.

By drawing together a picture across the transport sector, this study has informed the UK Government’s TDP and the decisions therein. The roadmaps set out recommended research and innovation interventions that need to be progressed in the coming five to ten years. The roadmaps also consider the recommended role of policymaking and fiscal or regulatory measures in helping to enable progress.