Can sustainable aviation fuels "soar"
Several international airlines have committed to steadily increasing the proportion of sustainable aviation fuels used in the coming decades. The picture shows Virgin Atlantic completing its first transatlantic flight using sustainable aviation fuel. Photo source:the ABC
Aviation is one of the important sources of global greenhouse gas emissions. In order to meet the challenge of climate change and reduce the adverse impact of the aviation industry on the environment, promoting the development and application of sustainable aviation fuels (SAF) has become a top priority.
General Electric Aviation, one of the world's largest aircraft engine manufacturers, is working with manufacturers, operators and others to ensure that SAF can be widely used in the aviation industry.
At the same time, many international airlines such as Finnair, Lufthansa, and British Airways have pledged to steadily increase the use of SAF in the next few decades.
"SAF is the key to reducing emissions in the aviation industry. Airlines need more SAF and are ready to take advantage of every drop of SAF." Willy Walsh, Director-General of the International Air Transport Association (IATA), said.
Help the aviation industry to reduce emissions
The advantage of burning SAF is that it does not increase the total amount of carbon dioxide in the atmosphere. The carbon dioxide produced during SAF combustion can be neutralized with the carbon dioxide absorbed during the production of this raw material, thereby reducing carbon emissions.
According to the official website of the World Economic Forum, the reason why SAF can do this is that it is a biofuel, a synthetic fuel made from renewable resources such as plant or animal materials, rather than fossil fuels. For example, SAF can be produced from edible oil and animal waste fats, and agricultural and forestry waste or municipal waste can also be used.
IATA's official website forecasts show that global SAF production will triple to 1.9 billion liters (1.5 million tons) in 2024, but still account for only 0.53% of aviation fuel demand in 2024.
Before 2030, about 140 renewable fuel projects producing SAF will be put into production. If all projects are put into production according to the announced plan, the total output of renewable fuels will reach 51 million tons by then, with production capacity almost spread across the world.
Commercial scale is difficult to expand
However, if the aviation industry wants to gradually approach the net-zero emission target by using SAF alone, there are still too many problems to be solved.
According to a report released by the World Economic Forum, the number of global SAF procurement agreements is increasing, but bio-based fuels only account for about 0.1% of total aviation fuel consumption. They are not widely used.
The biggest problem is that SAF has a lower energy density than traditional jet fuel, so when using the same amount of SAF, the aircraft's flying distance will be greatly shortened. In other words, the aircraft needs to carry a larger number of SAF to make long-distance flights.
Another problem is the high cost of SAF.
"There is currently no SAF that can compete with traditional jet fuel in terms of cost." United Airlines CEO Scott Kirby said.
Julie Kitcher, chief sustainability officer of Airbus, agrees that the challenge for SAF is actually how to produce it on a global scale and at an affordable price.
Currently, the supply of SAF is very small. According to the European Aviation Safety Agency, SAF accounts for only 0.05% of the fuel used in the EU. In addition, SAF costs three to five times more than "conventional" jet fuel.
Governments hope to change this. For example, the UK has introduced a "SAF Mandate" that stipulates that starting next year, 2% of all jet fuel must be SAF, increasing to 10% by 2030 and 22% by 2040. The European Union has a similar injunction, and the United States has provided subsidies to reduce SAF prices.
However, if SAF use increases, production will also increase significantly. This is another obstacle: a shortage of waste-based raw materials.
Need to diversify raw materials
There are many different methods or approaches to manufacturing SAF. It can be made from biomass such as waste edible oil, energy crops, wood, agricultural waste and even human waste. However, there are concerns that this will not meet the ultimate needs of the market. Some of these raw materials may need to be avoided to prevent environmental degradation. It seems that SAF production requires the use of a wider range of raw materials.
At the recent Farnborough International Aerospace Show, there were several important announcements related to the SAF.
A consortium including Airbus, Air France-KLM Group, United Energy Group, BNP Paribas, Qantas Airways, etc. announced plans to invest US$200 million to establish a new fund that will invest in "technologically mature SAF production projects, such as the use of waste-based raw materials."
At the same time, Boeing also said it has entered into a partnership with investment firm Clear Sky to promote the SAF production method pioneered by British company Firefly. The method involves converting human waste into a substance at high temperatures and pressures, which is then used to make SAF.
Whether SAF can lead the aviation industry to achieve net-zero emissions remains to be seen.
