The flight to net zero: Decarbonising the aviation industry

By Jack Arnold & Rebecca Shaikh

In 2020, the UK aviation industry was the first anywhere in the world to commit to net zero by 2050. Global airlines and governments through the International Civil Aviation Organisation (ICAO) have since followed suit. With the global net zero transition for aviation well underway, delivering at scale and speed is the biggest challenge collectively amongst industry and government alike. Airports can also increase their wider sustainability by considering avenues like noise pollution, responsible use of resources, waste disposal, and local air quality. All these items may not have a direct impact on carbon emissions but will help airports with their sustainability agendas.

Accounting for roughly 2% of global energy related carbon dioxide emissions, aviation emissions reached close to 800 Mt of carbon dioxide in 2022 – owing to a rapid growth in the aviation industry over the past few decades, one that surpasses that of rail, road, and shipping. Additionally, the aviation industry has been identified as one of the most challengingindustries to transition into a low-carbon state due to substantial infrastructure costs, long fleet lifespans, and limited opportunities for emissions reduction.

Nevertheless, there is plenty of room for optimism. From 2005 onward, the overall aviation emissions in the UK have managed to plateau, showing a mere 1% increase, in spite of a substantial 30% rise in carried passengers. Direct flight-generated emissions have played the largest part in this reduction through advancements in engine technology, fuel efficiency, and operational improvements. Manufacturers and airlines alike are continuing to ramp up investment into these technologies. Fuel-efficiency of aircraft has been consistently improving since the introduction of the first passenger jets in the 1950’s, with each new generation of plane reducing emissions by around 15-20%.

Recent breakthroughs have seen the emergence of sustainable aviation fuels (SAF) as a direct substitute to conventional jet fuel. SAF tackle some of the aforementioned issues with decarbonising aviation as they use the same supply infrastructure and do not require adaptation of aircraft or engines. As a result of these properties, they are termed “drop-in fuels” and can currently be mixed with conventional jet fuel to varying degrees of up to 50% under ‘ASTM D7566’, which is the standard which sets out the international minimum composition and performance guidelines for commercial aviation. SAF flights have been rolled out across the globe as governments and airlines confirm SAF targets, creating a demand for the low carbon fuel. In particular, the UK is finalising a mandate on conventional jet fuel supply to be 75% SAF by 2050, which would achieve 39% of the total CO2 mitigation. Nonetheless, currently the SAF market in the UK is in its infancy and requires substantial growth to reach a mandate of 10% consumption by 2030 from the UK government.

Meanwhile, manufacturers like Rolls Royce and Boeing are also trialling new engines capable of running on 100% SAF, thereby removing the requirement for conventional jet fuel on the runway. However as much as SAF serve as an important interim stop-gap solution by offering a potential 80% reduction in emissions, they are not completely carbon neutral due to emissions from the production of crops, fuel refining etc. Looking further ahead, long-term investments have also been made into the development of battery and hydrogen-powered aircraft, to aid in attaining a “true” net zero.

Whilst direct-flight emissions will play a pivotal role in the decarbonisation of the aviation industry, there are other avenues in which aviation can reduce its carbon emissions. Airports play a substantial role in contributing towards emissions, with sources suggesting airport emissions could account for anywhere in the region of 5-10% of total aviation emissions. Airport emissions are not limited to aircraft ground operations and airspace modernisation but spread wider into areas like electricity usage and surface access.

By amending the most energy-intensive processes, airports can realise large energy savings; examples of energy-saving measures include:

• Increasing the energy efficiency of terminal buildings - London City Airport has installed energy-reflecting windows to reduce heat gain;
• Upgrading heating and cooling systems - London Luton Airport replaced its old boilers with newer, more efficient units;
• Decarbonising ground power units – airports are now investigating the utilisation of biofuels in generators, substituting generators with options that have zero emissions, or adopting battery-based solutions.

SLR has supported several cross-disciplinary projects working to decarbonise the aviation industry.

Working with a sustainable energy solutions company, SLR was commissioned to provide an assessment of the emerging UK sustainable aviation fuel (SAF) market, identifying the most suitable product and route to market for advanced aviation fuels. The work encompassed:

• An overview of the sales route for SAF and synthetic paraffinic kerosene (SPK) throughout the supply chain;
• Estimates of the requirements of scale for sale of SAF and SPK with reference to the UK market;
• Description of the physical requirements for product delivery;
• Review of policy, regulatory requirements and incentives for the sector;
• Provision of a list of stakeholders in the UK SAF industry to encourage engagement and explore any opportunities for SAF production and sale;
• Conclusion on scale of SAF needs and entry routes to this market.

SLR have also provided technical expertise in the transport elements surrounding the airport’s function, this is a critical pathway to decarbonisation of the aviation industry, as typically half of an airport’s emissions arise from the surface journeys made by passengers and staff. SLR has helped airports across the UK develop surface access strategies and introduce new ground transport technologies for the sustainable development of airports and millions of UK air passengers annually.

One such example of SLR’s work in surface access matters is the City Airport Development Programme (CADP), London. The CADP is a £344 million privately funded investment to enable London City Airport to respond to forecast growth in passenger numbers and accommodate the next generation of aircraft. Plans included seven new aircraft stands, a parallel taxiway and a passenger terminal extension.

The development will transform the airport, one of East London’s largest employers in London’s Royal Docks, enabling the airport to welcome the new and quieter aircraft whilst adding additional capacity. Planning permission was granted in 2015, but our work continued through implementation. The permission granted by the UK Government will enable the airport to process 6.5 million passengers by 2025 and inject £1.5 billion each year into the economy. We have a detailed understanding of the airport’s transport characteristics and surface access arrangements, having provided strategic transport advice for several years. Our role has included:

• Engagement with key transport stakeholders, including the highway authority, TfL and DLR.
• An assessment of the capacity of the DLR and highway network.
• Provision of a transport charter for the environmental statements, assessing the effects of CADP during the construction and operational phases.
• Negotiation of planning conditions/obligations, including DLR.
• Upgrade contribution, a detailed Travel Plan and Delivery and Service Plan.

To learn more or to discuss your own decarbonisation project with our team, please get in touch.