2023 was the record year for air transport.But the road to sustainability is still long

The aviation sector will also have to achieve carbon neutrality by 2050.As?Through a mix of three different technologies:electric planes, hydrogen and sustainable fuels.Where are we at?

«Not on track», not on the right track.This is the judgment from the International Energy Agency on the efforts made so far by governments and companies to reduce emissions from aviation.In 2022, aviation was responsible for approximately 2.8% of global CO2 emissions.A figure that might seem negligible all things considered, yet this is not the case.The fight against climate change necessarily involves a reconversion of all sectors of the economy.And mobility is certainly not excluded, on the contrary.«If aeronautics only accounts for 3% of emissions, why are we so agitated?», asks Marcello Amato, director of Cira, the Italian aerospace research centre.«The truth – he explains – is that land transport will transform much faster than air transport.As a result, what today represents 3% will become 10, 15 and perhaps 20%.If we stand still, we will become the biggest polluters in the world."

2023:the record year of air transport

In 2019, the aviation sector emitted over 1,000 mega tons of carbon dioxide into the atmosphere.After a brief decline recorded during the pandemic years, climate-changing emissions from air transport have started to grow again since 2022, as has the total number of passengers.According to some estimates, 2023 will close with around 4.7 billion people transported (the highest figure ever) and experts agree that this number will continue to rise in the coming years.In the long term, however, environmental objectives remain ambitious.At the end of 2022, the countries of the International Civil Aviation Organization - the UN agency that deals with air transport - set the goal of achieving net zero emissions by 2050.But there is one element that risks ruining the plans:unlike other sectors, there are no technologies capable of eliminating the emissions produced in flight today.In all likelihood, the future of air transport will therefore pass through a mix of three different technologies:electric planes, hydrogen planes and sustainable fuels.

Electric and hydrogen airplanes

At the moment, electric propulsion is limited to very small, short-range aircraft.For these routes, the industry expects to arrive with flights powered exclusively by batteries by 2035 fuel-cell, as already happens with cars.The advantage of electric planes is that they produce no direct emissions, are low noise and have much lower maintenance costs than traditional aircraft.The problem, if anything, concerns the energy density and weight of the batteries.For regional flights, which carry up to 100 passengers, we are talking about hybrid planes, i.e. with two engines - one electric and one combustion - that collaborate with each other.For larger aircraft, the so-called SAFs come into play, an acronym for Sustainable Aviation Fuels.These are fuels that are produced without the use of fossil raw materials, such as oil or natural gas.

This family of fuels is already used in many commercial flights, mixed with traditional fuels and in even lower percentages.The objective, in the medium term, is to replace SAFs with hydrogen aircraft.Several companies have experimented with large engines, but there are still some issues to be resolved.«Recently Rolls Royce did some tests in Germany:in a week of tests they consumed half of the hydrogen available in the whole country", says Marcello Amato.The other problem is of an infrastructural nature:in fact, to power hydrogen airplanes it will be necessary to equip airports with structures for the transport and storage of this energy vector.«The real challenge for the future will be managing a system that no longer relies on a single technology, but which will inevitably be more complex and varied», specifies the Cira manager, who carries out various activities at the Capua (Caserta) headquarters of research precisely on the sustainability of the aviation sector.Internationally, Airbus has set the bar higher than anyone for hydrogen aircraft.The European company aims to fly the first experimental planes in 2027.

Doubts about the SAF

While waiting for the first electric and hydrogen aircraft to be perfected, the aviation sector is trying to reduce its emissions in other ways, for example by electrifying ground vehicles at airports and using SAFs.Precisely the latter are seen very positively by airlines, because they can be used on existing aircraft without too many difficulties.However, many people question whether these fuels can really be defined as sustainable.Currently, SAF represents less than 0.1% of aviation fuels and huge amounts of land would be required to meet the industry's needs.Sugar cane is often cited among the most suitable plantations for producing non-fossil fuels.A study published this year on Science Direct estimates that to convert the scheduled flight sector to SAF, 1.25 million square kilometers of plantations would be needed, approximately four times the surface area of ​​Italy.

The European strategy and American subsidies

The objective set by the UN is to achieve zero net emissions by 2050.To get there, countries are moving in no particular order.With the approval ofInflation Reduction Act, the United States introduced more than $3 billion in grants and tax credits in 2022 to stimulate the production and consumption of sustainable aviation fuels.The goal is to produce 3 billion gallons per year by 2030 and 35 billion gallons per year by 2050.The United Kingdom has also set itself a rather ambitious goal, with the Jet Zero strategy which plans to reach net zero emissions as early as 2040.Last November, the British airline Virgin Atlantic got the first transatlantic flight powered entirely by sustainable fuel.The European Union has recently approved a new regulation which provides for the use of at least 6% of SAF in European airports by 2030 and 70% by 2050.The European program to decarbonise aviation has been renamed Clean Aviation and currently foresees investments of over 4 billion euros, of which 1.7 allocated by the EU institutions and the remainder by companies in the sector.«Research is expensive and requires investments, but the European one is an absolutely concrete and feasible project – comments Antonio Blandini, president of Cira -.In Italy the main market leaders, starting with Leonardo and Avio Aero, are moving a lot."

Alternative solutions

Regardless of which is the best way to achieve zero emissions, the fact remains that with current technologies it seems unlikely that air transport can truly become sustainable in the short term.This is why some experts suggest another solution:reduce demand.France, for example, has banned short-haul flights to destinations easily reachable by train, while the International Energy Agency proposes a more cynical path and asks airlines to pass the costs (at least in part) onto consumers of research projects.By increasing flight prices, demand would fall and companies could use the increased revenue to finance the most promising technologies and accelerate the transformation of the sector.In this way, however, there would be a risk of transforming air transport into an exclusive service within the reach of a few.«Sustainability costs – explains Blandini -.The challenge is not only to achieve the objectives, but also to achieve them economically.We are giving it our all."

Cover photo:EPA/Caroline Brehman | An Asiana Airlines plane lands at Los Angeles airport (December 1, 2023)