Driving change by decarbonising the transport sector

Current situation and challenges faced

The transport sector plays a significant role in global greenhouse gas (GHG) emissions, accounting for nearly one-sixth of the total. In Europe, it contributes to approximately 25% of all GHG emissions and consumes 30% of the continent’s energy. Notably, transport remains the only sector where emissions continue to rise. Within this sector, the largest share of emissions (76%) originates from light and heavyduty vehicles in road transport. Maritime transport contributes 15% of GHGs, aviation accounts for 8%, and the rail industry represents a mere 1% of attributable emissions.

Internal combustion engines (ICEs) have undoubtedly revolutionised transport. Emerging at the end of the 19th century, the ICE remains the dominant technology across all transport modes. Cars, trucks, airplanes, and motorised shipping have shaped the modern world and have enabled the transport of people and goods across vast distances. Today, around 1.4 billion ICE vehicles worldwide run on fossil fuels, which leads to a significant environmental impact through GHG emissions, hazardous gases, and particulate matter, also causing health problems and geopolitical dependencies.

As an alternative, battery electric vehicles (BEV) and Plug-In Hybrid Vehicles (PHEV) have gained strong momentum for road transport. BEVs are three times more efficient than ICE vehicles and have a much lower carbon footprint during their lifetime if they consume electricity from renewable energy sources. PHEVs often still produce substantial emissions but are ostensibly a stepping-stone towards BEV. Among the challenges is the fact that more carbon is emitted in the production of these vehicles (especially for the batteries) and that new infrastructure for charging must be built.

Global CO2 emissions in transport sector in 2022 by mode (%)

Even existing ICE vehicles can be made more sustainable and environmentally friendly by using renewable fuels. Renewable fuel options are available as biodiesel or renewable diesel, biogas or bio-methanol; or as sustainable aviation fuels (SAF) for airplanes. Those fuel options are increasingly blended with fossil fuels thus reducing the carbon footprint while playing an essential role in keeping the last internal combustion engines running. One challenge of renewable fuels is the fact that the road, marine and aviation sectors compete for the same renewable fuels. This means that sectors with the highest paying capability will drive the pricing.

Although lagging a few years behind BEVs in terms of their technical development, the potential of hydrogen cars is also gaining a certain traction in the field of transport, for aviation, and to a lesser extent long-haul trucking and maritime. Renewable hydrogen is a zero-emission technology but is set to be predominantly applied in the context of the decarbonisation of the industry.

Looking ahead

To draw a pathway away from fossil fuels in the transport sector, a combined set of questions must be answered about vehicle technology, alternative energy sources, and infrastructure. Answers look different for the various transport modes. For road transport, by far the largest share of vehicles, including passenger cars and vans, municipal buses, and short-haul delivery trucks, will be battery-electric.

Depending on the usage pattern and the power grid, a small share of long-haul trucks, buses and cars that need to be kept in service will use hydrogen or renewable fuels.

Long-haul maritime transport has the option of using fatty acid methyl ester (FAME) biodiesel, renewable diesel, bio-methanol, biogas, and green ammonia.

A shore-side power supply will reduce the fuel consumption and emissions of large vessels mooring at the quayside. A significant share of short-haul vessels, especially ferries, work boats, and leisure boats, will also be electrified. Electric boats can dramatically increase energy efficiency and reduce environmental impact when they use foiling technology. The first prototypes for such boats are becoming available.

Energy use in road transport1 in Europe between 2020 and 2050 (PWh)

In aviation, SAF (also known as renewable jet fuels) are going to be crucial in the coming decades for enabling low-carbon long-haul flights. Hydrogen will play a role in the transformation of aviation into a carbon neutral system over the next few decades. Battery-electric planes will serve short-haul flights (below 500 km) and niches such as sightseeing or pilot training.

In most cases, the higher efficiency of the drive train, lower energy costs, and the more direct use of electricity from renewable energy sources outweigh the downsides of BEV (limited range and longer refuelling times). Critical for success is that energy networks are upgraded for the increased electricity demand, and that power from renewable energy is available.

However, electrification is not always possible. Renewable fuels and hydrogen may be needed for heavy-duty long-distance transport in road, maritime and aviation. Generation capacities for renewable fuels and hydrogen also need to be increased and new technologies will be required, such as fuels based on waste and residues, and the conversion of electricity into e-fuels (also known as ‘power-to-fuel’ or ‘power-to-X’).

Besides introducing more sustainable drive trains and energy sources, two more considerations are important for reducing fossil fuels in transport. First, it must be considered when transport demand can be reduced, for example, through consuming locally produced goods or avoiding travel through online meetings. Second, the shift to rail or even bike - which are the most sustainable transport modes for people and goods - can bring down carbon emissions dramatically.

Alternative fuels for the various transport modes and their approximate vehicle share by fuel by 2050