Clean air progress on highways and harbours - William Bonnell and Robin Koerner

Comment by William Bonnell, Transport Systems Engineer, and Robin Koerner, Transport Systems Engineer at Energy Systems Catapult.

Improving air quality is vital for improving the health of the nation. Air pollution emissions have decreased steadily in the UK in recent decades. A classic example of this is in transport with regulations on vehicle emissions and policies such as emission charges. Research has shown that existing air pollution regulations could prevent 6,751 early deaths by 2030.

More needs to be done to keep the improvements going. For example, in 2022 over 95% of residential addresses in the UK exceeded the World Health Organisation limits for one of three main pollutants. These include nitrogen dioxide (NO2) and two grades of particulate matter (PM). These are PM10 and PM2.5 which are particles that have a diameter of about 10 and 2.5 micrometres respectively. Other nitrogen and oxygen compounds also contribute to air pollution, called NOx pollutants.

Air quality gives us another lens to examine the work we do at Energy Systems Catapult to accelerate Net Zero innovation. This is especially true of the work our transport team delivers. Two key sectors where emissions have proven challenging to abate are the road freight and maritime sectors.

Road freight

Road transport is a major contributor to UK air pollution. Burning fuel, especially diesel, in road vehicles accounted for just under a third of all UK NOx emissions in 2021. They were also a significant contributor to particulate matter pollution, accounting for 14% of PM2.5 and 12% of PM10 emissions. Some of this particulate matter comes from vehicle engines, but another major source is the result of brake pads and tyres wearing down.

We must enable new kinds of heavy goods vehicles (HGVs) to improve air quality. This is because HGVs are more polluting than smaller vehicles like cars. HGVs produced 21kT of NOx pollution in 2021, about 11% of the total road transport emissions. This is despite HGVs only accounting for 6% of the total miles driven. In other words, HGVs are more polluting on a per-mile basis than the more numerous smaller vehicles on the road. This effect is even greater for CO2 where HGVs account for 20% of road transport emissions.

Smaller cars and vans produce more air pollution overall because there are more of them. However, many of their journeys are replaceable with less polluting alternatives. Beyond the move to zero emission vehicles, these journeys are often suitable for the uptake of active travel (e.g. walking or cycling) or public transport. These replacement journeys can then be further encouraged with appropriate planning or policy. This is much harder to do with HGVs where fewer alternatives are plausible. To improve air quality then it is vital that we transition away from legacy trucks which burn diesel to those powered by electricity (eHGVs) or hydrogen.

The eFREIGHT 2030 consortium – led by Voltempo and including members such as the Catapult, Kuehne+Nagel (UK) Limited, Wincanton Group Limited, and Maritime Transport Limited – can help enable the transition by demonstrating the abilities of these new, low-emission HGVs. The project will do this by introducing 100 electric HGV 4×2 and 6×2 tractor units, and 32 new charging locations, all of which will have megawatt-charging capacity from day one.

The Catapult will also explore how the transition can be accelerated. We will do this with national-scale modelling that will explore how different scenarios affect the new HGV market. We will also consider what infrastructure we need to support it. The results of this modelling and the five year trail can then be combined to provide a clear path for transitioning to low-emission HGVs.

Improving air quality provides extra urgency to the need to transition to low-emission HGVs. In particular, those that operate in suburban and urban areas worst affected by road transport air pollution. Luckily, these are exactly the kind of HGVs that are most likely to be suitable to transition to eHGVs. We can therefore be hopeful that projects like eFreight 2030 can help further reduce air pollution and provide the clean air we deserve.

Ports and maritime

Ports and the maritime sector are significant contributors to air pollution. In 2016, domestic shipping in the UK accounted for 10% of the country’s total domestic NOx emissions, 2% of primary PM2.5, and 7% of SO2 emissions. However, these figures exclude emissions from international ships visiting UK ports, indicating an even broader impact.

The international shipping industry is undergoing significant changes to reduce air pollution. In 2020, stricter global limits on the sulphur content of fuel came into effect. In England, major ports are developing air quality strategies aimed at mitigating emissions from port operations. This effort aligns with the broader Clean Air Strategy, which emphasises the need to reduce emissions across ports and associated waterways, including those from shore activities and visiting ships. The government is also reviewing the expansion of Emission Control Areas (ECAs) in UK waters, highlighting a commitment to minimising the maritime sector’s environmental and public health impacts.

To tackle these challenges, the Clean Air Strategy requests larger English ports to establish Port Air Quality Strategies (PAQS), to provide a clear understanding of air quality issues within ports and outline actions to address emissions under port control. Although port operators may not directly influence emissions from all ships, especially those adhering to international regulations, they can still implement measures to mitigate their own operational impacts, such as managing their vehicle fleets or improving cargo handling efficiency.

Projects like Port of Aberdeen Shore Power Technologies, as part of the Zero Emission Vessels and Infrastructure (ZEVI) competition, showcase the collaborative efforts from Energy Systems Catapult to address these challenges.  The Decarbonisation Roadmap and Assessment Framework created in this project will highlight the importance of air quality, especially in urban-centered ports like Aberdeen North Harbour. These initiatives not only drive environmental benefits but also provide social value by ensuring cleaner air for surrounding communities.


Improving air quality clearly provides us with another way to frame our work at the Catapult. Projects like those mentioned above aim to help accelerate Net Zero. If successful, they will also help reduce air pollution caused by the transport sector. So, we can view Net Zero as continuing the trend of improved air quality observed over the last few decades. Net Zero then not only improves the health of the planet, but it also improves the health of those who live on it.

Integrating the Transport and Energy Systems

Whole systems approach to helping the transport and energy sectors integrate their physical, market, digital, and policy systems.

Find out more

Want to know more?

Find out more about how Energy Systems Catapult can help you and your teams