Meeting the stratospherically tall order of zero carbon aviation

Have you ever felt flygskam? Literally translating as “flight shame”, the term was coined in Sweden in 2018 to describe the low-level guilt that jet-setting can induce as the impact of climate change became ever more apparent. As air travel peaked pre-pandemic, flygskam began to gather momentum, with short-haul flights decreasing and train travel peaking. But since the global grounding of Covid, jet setting has rebounded to record levels. With 4.35 billion passenger journeys estimated to take place this year, flygskam, it appears, is so 2019.

Aviation may account for just 3 per cent of global carbon emissions but as other industries become cleaner – and demand for flying continues to rise – that percentage will continue to increase for this “hard to abate” sector, with some estimates suggesting it could be as much as 27 per cent by 2050.

Yet the aviation industry has committed to achieving net zero carbon emissions by 2050. Most say this is a tall order, others that a multitude of measures may be the answer, such as sustainable aviation fuel (SAF), new aircraft technologies and other efficiencies.

Dr Marina Efthymiou is associate professor in Aviation Management at Dublin City University’s Business School, where she works on policy recommendations and advises the aviation industry on the sustainability transition. Decarbonising aviation is a huge challenge, she admits.

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“Since Covid everyone wants to go to the sun. There are new markets springing up – a lot of people want to fly to Africa from Europe or to Saudi Arabia,” says Efthymiou. In fact it is estimated that 10 billion passenger journeys will take place in 2050, which means, she says, that the industry “must abate 1.8 gigatonnes of carbon that year”.

While Efthymiou is more optimistic than most about the challenge aviation faces to decarbonise, she warns that effective policy will be the key determinant in its success.

“We have gained a lot of efficiencies due to technological advances with aircraft but aviation must rely on a basket of measures rather than a single solution to decarbonise,” she explains. “It is possible as long as all the different steps work [but] modelling exercises show that all of these things are set to fail unless there is policy support.”

This basket of measures includes new technologies, changes to infrastructure/operations and carbon offsetting/carbon capture utilisation and storage. But the vast majority of the reduction will come from sustainable aviation fuel (SAF) (65 per cent).

The reality, Efthymiou says, is that decarbonisation is an expensive business. “The aviation industry does not yet have a clear incentive for doing the right thing,” she adds. “They do need policy support and clarity from policymakers, who need to look at how they can incentivise the development of sustainable aviation fuel, how they can scale up the technology and fund innovation.”

For example, biofuels are three to four times as expensive as fossil fuels. This is in addition to the fundamental challenges associated with producing them. “Biofuels can take a lot of water and a lot of land so can lead to higher carbon than they want to produce right now,” explains Efthymiou.

Policy is shifting in this regard; from 2025, the new “Refuel EU” regulation will require aviation fuel to be a blend of SAF and fossil fuels, with the proportion of SAF to gradually increase over time – from two per cent in 2025 to 63 per cent in 2050.

“Economies of scale will then apply, meaning the price will come down,” says Efthymiou. Yet the challenge seems enormous, given the low base they are starting from – SAF production must increase from 100 million litres today to at least 449 billion litres in 2050. Forward purchasing agreements are also required in order to ensure there is a market for SAF given the intensive production process.

Earlier this year, the European Parliament voted to revise its emissions trading system for aviation, agreeing to phase out free allowances to airlines by 2026 – a year earlier than originally planned. This means the cost of offsetting carbon will shoot up from €85 per tonne to €250 per tonne, Efthymiou says.

Hydrogen as a potential fuel is also the subject of much discourse but its widespread adoption is even further off. It may be used in short-haul flights from 2035, says Efthymiou, but will not be used in long haul by 2050. “Hydrogen, as a fuel, requires a lot of space so it reduces the payload,” she explains. “You could have a huge plane with very few passengers, which makes it economically unfeasible.”

According to Chris Brown, head of strategy at KPMG, scaling of SAF supply is not currently happening at the rate the sector needs for its 2030 goals, let alone the more aggressive targets for later that decade.

“This highlights the aviation sector’s dependence on the investment priorities of other sectors – such as energy and institutional investors,” he says.

Contrail mitigation is the closest the sector has to a silver bullet, Brown says, with the ability to roughly reduce by half the impact of flying with technology that exists today – at a fraction of the cost of SAF premiums. He also notes there is “interesting potential” long term to create net cooling contrails only. The main problem is that, to date, these non-CO2 impacts haven’t been considered by airlines as part of their footprint.

When we look at climate change, one element is CO2 but the non-CO2 is equally or even more significant, such as the NOx contrails

—  Dr Marina Efthymiou

Efthymiou agrees, saying the debate has been too “narrowly focused” on carbon emissions, with almost complete disregard for non-carbon emissions such as NOx (nitric oxide (NO) and nitrogen dioxide (NO2).

“When we look at climate change, one element is CO2 but the non-CO2 is equally or even more significant, such as the NOx contrails. With the current approach, we might reduce carbon but then have a higher output of NOx or other gases that contribute to climate change.”

However, EU requirements on non-CO2 reporting will kick in later this decade for relevant flights. From 2025 the release of so-called “non-CO2 effects” must be reported by airlines; this includes harmful gases such as nitrogen oxides, sulphur dioxide, and soot particles emitted from jet engines.

But experts say that how the climate impact of aviation has been measured to date has been inconsistent, if not wholly inaccurate.

Cathal Foley is chief executive of Fexco’s Platform for Analysing Carbon Emissions (Pace), which aims to address these inconsistencies. The aviation needs “really good quality data” to support its decarbonisation journey and Pace aims to fulfil that unmet need, says Foley.

The innovative platform provides data on carbon emissions per flight from airlines and aircraft, as well as whole life cycles emissions, and can also model the impact of any changes airlines or manufacturers make to reduce their carbon footprint.

“It comes down to ‘measure, manage, mitigate the journey’,” Foley says. “If you can’t measure it, you can’t go anywhere.”

The level of granularity is impressive given the sheer volume of data; for 2022, they have analysed more than 30.5 million flight cycles involving more than 36,000 aircraft and total carbon emissions of more than 750 million tonnes. Unsurprisingly, Fexco Pace has a number of pillar clients already, including major banks such as JP Morgan, as well as lessors and investors.

The consistency in this data allows a degree of transparency and will allow airlines access sustainability-linked finance worth trillions, Foley says.

“This ultimately allows for new types of financing transactions to be arranged where you have independent data underpinning what’s there. It’s about breaking that elasticity that exists between revenue growth and passenger growth and carbon emissions, where we allow the benefits of global travel to exist without having the associated correlation with CO2 output.”

A voluntary initiative to offset carbon emissions – the Carbon Offsetting and Reduction Scheme – will be mandatory from 2027. Foley says this and new EU rules on carbon allocations should be viewed as an opportunity and not simply a compliance burden. “This should be looked at as a chance to create new commercial value and new financing structures and be more efficient in how they operate,” he says. “Otherwise you are not creating that positive behavioural change because people will always do the bare minimum when they have to comply with regulations.”

Efthymiou believes that, flygskam or not, air travel for pleasure will continue to increase.

“If we stop flying because we are ashamed to create emissions, then we all end up completely isolated from each other. Whether we like it or not, we live in a global society,” she says. “We just need to do it more responsibly and find ways of doing it more sustainably.”