Reducing greenhouse gas emissions from heavy-duty vehicles in Europe

The European Green Deal aims to achieve climate neutrality by 2050. Meeting this goal will require large-scale changes in the transport sector, which comprises approximately a quarter of EU greenhouse gas (GHG) emissions. A 90% reduction in GHG emissions from transport will be needed to attain climate neutrality, and every part of the sector will have to contribute to the reduction.

So far, the sector has proven challenging to decarbonise. GHG emissions from the EU  transport sector have not followed the  general downward trend in EU emissions (EEA, 2021a). The EU and Member States have taken or planned to take a number of actions, and these need to be consistently implemented and strengthened to ensure that the trend is reversed. 

This briefing focuses on carbon dioxide (CO₂) emissions from heavy-duty vehicles (HDVs). Road transport is the largest contributor to transport emissions in the EU, and HDVs are responsible for around a quarter of EU road transport emissions. CO₂ is the main greenhouse gas emitted by the road transport sector, accounting for nearly 99% of all GHG emissions. Therefore, it is relevant to assess trends in HDV CO₂ emissions and prospects for HDVs contributing to the achievement of the European Green Deal objectives.

CO₂ emissions from HDVs are increasing

Similar to other segments of the transport sector, HDV emissions have not decreased compared to 1990. Despite a decline following the 2008 financial crisis, annual CO₂ emissions increased by 29% between 1990 and 2019. In fact, CO₂ emissions from HDVs in the EU have increased every year since 2014 (Figure 1). The dynamics of the growth in emissions have varied among the Member States, with some experiencing much sharper increases compared with the EU average over the given period. In 2020, these emissions decreased because of the COVID-19 pandemic. As the drop was not due to systemic changes in the sector, it is expected that it will rebound.

Figure 1. Trends in CO₂ emissions from heavy-duty vehicles in the EU, 1990-2020

Among the various categories of HDVs, trucks are responsible for about 85% of emissions, while buses and coaches are responsible for the remainder. Different types of policies contribute to reducing CO₂ emissions from HDVs. At the EU level, the key policies are the Effort Sharing Legislation, the EU Emissions Trading System (proposed extension of emissions trading to road transport) and the Energy Efficiency Directive. Fuels in the transport sector are addressed by the Renewable Energy Directive and the Fuel Quality Directive. Vehicles are targeted by CO₂ emissions standards that are complemented by the Car Labelling Directive, the Alternative Fuels Infrastructure Directive (proposed to become a regulation) and the Clean Vehicles Directive.

At the Member State level, concrete instruments discussed and planned include constructing electric road systems, such as a CO₂ component in the tolls for trucks, improving rail infrastructure (Umweltbundesamt, 2022), and incentivising zero emission urban transport through electric and hydrogen buses (Centre for Climate and Energy Analyses, 2022). 

Transport demand is the main driver behind trends in truck emissions 

A recent EEA report reviewed the progress and future perspective of decarbonisation in the road transport sector (EEA, 2022b). To explore the factors driving the trends in GHG emissions from road transport over time, a decomposition analysis was conducted for truck emissions in the EU Member States (EU-27). The analysis considered the following possible factors as drivers of emission trends: 

• freight transport demand;
• the modal share of trucks in inland freight transport demand;
• the energy efficiency of trucks;
• the share of fossil fuels in truck fuel consumption, with biofuels assumed to be carbon neutral;
• the carbon intensity of fossil fuels consumed by trucks 

Figure 2 depicts the relative importance of the different factors driving total CO₂ emissions from trucks and their development between 2000 and 2019.

Figure 2. Decomposition analysis of the CO₂ emissions from trucks in the EU-27, 2000-2019 — percentage contribution of various factors

CO₂ emissions from trucks were 5.5% higher in 2019 than in 2000. The period is marked by several years of reductions in emissions following the economic crisis. However, this did not have a lasting effect and emissions started rising again. Freight demand is a key factor contributing to these trends. The total demand for inland freight transport increased by nearly 25% in the period 2000-2019. Cycles of emission increases and decreases are closely linked to trends in demand.

In the EU context, the causes of the increased demand are diverse. They include the transport intensity of the economy, the fact that mobility patterns are at different stages of development across the EU, and that economic growth has contributed to reduced inequality among the EU Member States.

In 2019, trucks also carried relatively more goods than other transport modes compared to 2000. More specifically, while transport activity in the EU’s inland waterways and railways increased by 5% between 2000 and 2019, truck transport rose by 31% during the same period. Because of these trends, the share of freight transported by trucks increased from 72% in 2000 to 76.4% in 2019, while the share of rail and inland waterway activity decreased. 

The increase in overall demand for freight, and the share of trucks in meeting that demand, are the main factors in increasing emissions from trucks. The increase has been limited during periods of demand growth through improvements in the energy efficiency of freight operations. The energy consumption per tonne-kilometre transported decreased by almost 15% between 2000 and 2019, which limited overall emissions. 

The improved efficiency of individual vehicles is likely to have played a role in this development. International trucks drive long distances, and fuel cost is a significant part of total cost. Therefore, freight firms have a strong incentive to improve fuel efficiency. In addition, some of the reduced fuel consumption per tonne-kilometre can be explained by improvements in freight operations, such as improving logistics so that vehicles can carry larger loads.

Another factor which appears to contribute to limiting increases in CO₂ emissions is the wider adoption of biomass fuels, which are considered carbon neutral in the emissions inventory. However, the feedstock used to produce biofuels is decisive, as it can negatively influence emissions reduction, thus impacting the use of biofuels as a solution. For example, indirect land use change that can result from growing crops for biofuels can potentially diminish emissions reduction.

A similar analysis for passenger cars indicates that modal shifts to other transport modes, such as rail, buses and coaches, has not occurred in the last two decades. Rather, the share of passenger-kilometres travelled by cars has increased.

To ensure that the trend in road transport emissions is reversed, a combination of ‘avoid’, ‘shift’ and ‘improve’ (ASI) strategies will be necessary. ‘Avoid’ strategies are directed towards reducing the number of trips and their length (i.e., addressing demand). ‘Shift’ strategies aim to shift transport activity to more efficient modes, while ‘improve’ strategies are about improving vehicle and fuel technologies to make them more efficient.

In the coming decades, more zero-emission vehicles will be on the roads, and existing vehicles will need to become more carbon and energy efficient. To ensure a faster and more complete transition, a shift to transport modes with lower emissions will be important. The EU will also need to move towards greater sustainability in other areas of the economy, including targeting transport demand directly or via incentives in other areas, such as local production and circular economy initiatives. 

Move to more efficient transport modes — the essential ingredient in reducing emissions 

One of the means to reduce GHG emissions from transport is to shift to transport modes with the lowest emission. In the case of HDVs, the role played in the wider transport system is different for passenger and freight transport.

For freight transport, carrying cargo by road (using trucks) has significantly lower GHG emissions than air cargo. However, road freight emits significantly more GHG than transporting goods by either rail or ship (Figure 3, left). Hence, finding ways to transport freight by rail or ship instead of by road could contribute to the goal of reducing transport emissions.

For passenger transport, cars have the highest emissions per passenger-kilometre, together with aviation, while public transport modes (rail, buses, coaches) are more efficient (Figure 3, right). Thus, shifting from cars or planes to public transport modes, such as buses and coaches or rail, can help reduce GHG emissions from passenger transport. While shifting from cars to buses or coaches would increase the demand for (and emissions from) HDVs, it would result in a decrease in overall transport emissions. In turn, buses, especially those used in urban transport, can be made less carbon intensive, by for example, switching to zero-emission buses.

Figure 3. Greenhouse gas emission efficiency of different transport modes for freight (left) and passenger (right)