With sustainable aviation fuels still more than a decade away from being widely available, the sector is also focusing on efficiency improvements in the air and on ground and electrification, reports Mike Scott
As the global economy slowly but surely shifts to a lower-carbon model, some of the most intractable industries – steel and cement, for example – have moved faster than anyone could have imagined, while new solutions such as hydrogen are scaling up rapidly.
One sector, though, is lagging behind: aviation. The sector accounts for about 2.8% of global CO2 emissions, with a further impact from non-CO2 greenhouse gases because most of its emissions are made at altitude. What is more worrying, though, is that emissions from flying have risen by 2% a year since the turn of the century and they could reach a fifth of total emissions by 2050.
There are a number of reasons for this. Partly it is the laws of physics: it is hard to find a fuel or power source that is sufficiently energy-dense, yet also light enough, to replace kerosene, especially on long-haul flights.
Another reason is the laws of man – or lack of them. “The aviation sector has been under-regulated and undertaxed for decades, which is why low-carbon technology has been slow to come to market,” says Jo Dardenne, aviation manager at Transport & Environment, a Brussels-based non-governmental organisation (NGO).
Airlines didn’t go to the ICAO for bailouts during the pandemic, but to national governments
The 1944 Convention on International Civil Aviation, better known as the Chicago Convention and introduced to help the industry grow in a post-war world, makes it difficult for governments to tax aviation fuel.
“The industry says international aviation emissions should always be regulated at international level, but airlines didn’t go to ICAO (the International Civil Aviation Organization) for bailouts during the pandemic, but to national governments,” she adds.
“There is now more of a view that if they have been helped by the government, they should have to contribute to the government budget and the fight against climate change.”
Sentiment towards the industry, and within it, is starting to change – slowly, though. There is a growing feeling that it is unfair that aviation is not taxed when other activities are, not least because 1% of people cause 50% of global aviation emissions, according to Transport & Environment.
“It was a crucial driver for the gilet jaune protests in France,” Dardenne points out. “People were asking why they were paying tax to drive and heat their homes, when airlines were not paying tax.”
In advance of the COP26 climate conference in Glasgow, Scotland, last November, the sector committed to achieve net-zero carbon emissions by 2050, which it said would be “supported by accelerated efficiency measures, energy transition and innovation across the aviation sector and in partnership with governments around the world”.
SAF is where the future lies. It’s the only way the industry can continue to grow
The industry is largely pinning its hopes on sustainable aviation fuels (SAF), which are made from sources such as biomass or municipal waste. (Read more)
“SAF is where the future lies,” says Dardenne. “It’s the only way the industry can continue to grow. However, we can’t expect a sufficient amount of SAF to be available until the mid-2030s. Aviation fuel will still be 95% fossil fuel-based in 2030.”
Members of ICAO set up the Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) as long ago as 2016, but Dardenne says “there are so many flaws in CORSIA – in principle, in practice and in implementation. Fundamentally, it’s an offsetting scheme. It’s like saying you will lose weight and pay someone else to go to the gym for you.”
Many critics feel that CORSIA, which came into effect in January 2021, five years after the scheme was created, sums up the industry’s approach to tackling climate change – too little, too late. The German Aerospace Centre says that while the CORSIA targets can mitigate the increased climate impact of air transport, the current measures will not be enough to help limit temperature rises to 1.5C. (See The rocky road to guilt-free travel)
Nonetheless, aviation has already made progress. It has been becoming more efficient by 1% a year since the 1980s and the sector believes it can double that, cutting the amount of energy it uses by 2% every year, says Manosij Ganguli, head of mobility decarbonisation at the Energy Transitions Commission.
Jason McClain, senior director in ventures and innovation strategies at Boeing, says that aircraft makers are taking a portfolio approach across different time horizons. In the short term, a range of different technologies are being applied to new aircraft, which are much less polluting than their predecessors. “Every new generation of aircraft has a 15-25% efficiency improvement over the previous one. But there is more focus on this now, and we’re looking to bend that curve still further.”
Battery technology is advancing at pace, with numerous U.S. government agencies now funding research
Multiple technologies are being tested by engine and airframe manufacturers, from fin design and turbo props in engines, to LED lights in cabins and seats made from aluminium, which reduce weight and therefore fuel consumption.
A number of manufacturers are developing electric aircraft, including Siemens, Airbus and Rolls-Royce, which has built a battery-powered plane that can fly at more than 300mph. United Airlines in the United States plans to have electric aircraft in service by 2026. However, the 100 19-seater vehicles, supplied by Swedish startup Heart Aerospace, will be used only for short flights.
U.S. startup Wright Electric plans to unveil a 100-seat plane by the same date, and it is set to deliver an electric commercial passenger jet with a range of 800 miles to enter service by 2030. EasyJet is set to be the first customer.
“Battery technology is advancing at pace, with numerous U.S. government agencies now funding research into electric aviation,” says Johan Lundgren, chief executive of easyJet.
The low-cost carrier was the first major airline to offset the emissions caused by all of its flights, although it highlights that this is a temporary solution. “We have now offset more than 9 million passenger journeys, but we are clear this is an interim solution until new technologies become available.”
As with other forms of transport that are decarbonising, the benefits look set to be financial as well as environmental. It is not just about the cost of fuel, either, even though in today’s pricing landscape, that is clearly a significant factor.
United Airlines estimates that the cost of maintaining its electric fleet will be a staggering 100 times less than conventional aircraft. This will make many short-haul routes from regional airports, which were abandoned because they were not profitable, viable again.
By hybridising sources, you can reduce the fuel burn of aircraft and therefore the environmental impact
About 200 companies are looking at electric aviation, from Wright Electric’s 100-seater to eVTOL (electric vertical take-off and landing) air taxis. Wright is also looking at retrofitting battery propulsion into existing short-haul BAe 146 aircraft, which would considerably speed up the rollout of electric planes.
Another measure that may speed the adoption of low-carbon aviation is some form of hybridisation, using both batteries and fossil fuel, which helps to mitigate the disadvantages of pure battery powered aircraft, such as the extra weight, but still cuts emissions.
“By hybridising sources, you can reduce the fuel burn of aircraft and therefore the environmental impact,” says Dr Xavier Roboam, deputy director at the University of Toulouse’s LAPLACE lab. “It’s the first step before the final step, which may be zero-emission, fully electric aircraft.”
According to Germany’s Sustainable Aero Lab another area that will offer significant benefits is the digitalisation of aircraft, and the entire aviation infrastructure.
“Many steps in today’s airline operations stack are still handled by humans, yet they could be automated and optimised for greater efficiency, especially when it comes to limiting fuel burn,” says the organisation, which identifies and helps startups and projects that can reduce the climate impact of aviation. It is supported by the Hamburg Ministry of Economics and Innovation (BWI) and funded through the Hamburg Investment and Development Bank (IFB)
For example, airlines can use more efficient flight routing, using detailed weather forecasts and real-time air traffic updates.
Better data-sharing between air traffic control centres would also greatly improve flight routing, while using big data to co-ordinate use of airspace would bring further efficiencies. This will be crucial when the skies also have to accommodate cargo drones and air taxis on top of today’s airliners.
London City Airport cut its cooling bills simply by installing energy-reflecting windows
There are also efficiency gains to be made on the ground. Airports, for instance, could apply AI-backed software solutions to optimise departure and arrivals schedules, improve congestion management, predict accidents, and increase overall turnaround efficiency via computer vision, consequently improving airport utilisation.
Farnborough Airport, the UK’s busiest airport for private jets, says it has reduced its “controllable” emissions by 70% in the last decade. It buys renewable energy to power its operations, and uses that green electricity to charge a fleet of electric vehicles that it uses on site and to power an increasing number of electrical ground power units.
Other measures recommended by the Airport Operators Association (AOA) include upgrading heating and cooling equipment, with options ranging from heat pumps to biomass boilers, and variable refrigerant volume air conditioning units. London City Airport cut its cooling bills simply by installing energy-reflecting windows. A number of airports have also switched to LED or solar-powered airfield lighting.
Airports can also provide electricity on-stand, so aircraft do not have to run their engines while on the ground, and reduced engine taxiing. In addition, the AOA reports that “airlines have implemented take-off procedures which reduce engine thrust settings to the level actually required … given the aircraft take-off weight, current weather conditions and the length of the runway available,” which results in a small cut in emissions and also improvements in air quality.
Ultimately, a decarbonised aviation sector will be focused on hydrogen, either as a fuel to be burnt or used to power fuel cells, says McClain at Boeing. But it is still early days. “We’re starting to explore what makes sense. We’re working with our supply chain, doing internal R&D and working with startups as well.”
The aviation industry is at a crossroads, Sustainable Aero Labs says, and it must go beyond current efforts to slash carbon emissions. “The winning formula to cut total emissions in half through 2050 requires a mix of continuous improvements of current technologies and, more importantly, revolutionary solutions.”
Mike Scott is a former Financial Times journalist who is now a freelance writer specialising in business and sustainability. He has written for the Guardian, the Daily Telegraph, The Times, Forbes, Fortune and Bloomberg.
This article is part of the summer 2022 edition of The Ethical Corporation. See also:aviation industry electric aviation sustainable aviation fuels ICAO CORSIA Carbon offsetting