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Earth overshoot day is becoming more worrisome as each year passes. What is overshoot day about? Find out more about this term and what it implies.
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Could Aviation Be Decarbonized and Become Sustainable?
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With the pandemic all but over and travel back on the agenda, the aviation industry is set to see huge growth - in fact, emissions could triple within the next three decades alone. Obviously, this is bad news for the environment; the aviation industry is responsible for a significant amount of greenhouse gases and every flight we take increases our carbon footprint. So you may be wondering if there is a solution on the horizon and what needs to be done to achieve guilt free flying?
👉 In this article we’ll explore why the aviation industry is so bad for the environment, and what is being done to decarbonize it.
Whats the issue with the aviation industry?
Air travel accounts for 2.5% of global carbon emissions, and together with other gases and the water vapor trails produced by planes, the industry is responsible for approximately 5% of global warming emissions. Even more concerning is the fact that the aviation sector is rapidly growing - experts estimate that aviation emissions could triple in the next three decades.
These percentages seem comparatively small, especially when you consider that road transport accounts for almost 16% of global carbon emissions, however, only a very small percentage of the world's population actually fly (approx 3%). This means that a very small fraction of the global population is responsible for a disproportionately large portion of the emissions.
To put this into context, take the example of a flight between London and New York. A return ticket on this route will produce around 986 kg of carbon dioxide per passenger. There are 56 countries in the world where the average citizen produces less emissions in their entire year!
Even a short-haul flight between London and Rome accounts for more CO2 emissions than the average CO2 emission produced by people living in 17 different countries annually.
🛩️ Why is flying so bad for the environment?
Why are planes so bad for the environment? Most people will be aware of their carbon emissions - planes run on fossil fuels which means that they produce large quantities of CO2. However, this is not the only way that flying harms the environment. Planes also contribute to global warming through the creation of water vapor, nitrogen oxides, carbon monoxide, and soot. These non-CO2 pollutants contribute twice as much to global warming as the CO2 produced by the aircraft.
❓ How does water vapor harm the environment? Water vapor (the white trails that you see behind planes) condenses around the soot from the plane's exhaust and freezes to form cirrus clouds which can last anywhere from minutes to hours. The ice crystals that form inside them are able to trap heat which means that they warm the climate. Research suggests that the net effect of these contrail clouds is that they contribute more towards atmospheric warming than all the CO2 that has ever been produced by planes!
Is sustainable flying in our future?
Given that flying is so bad for the environment, and that the industry is predicted to continue to grow, what can we do to reduce its impact?
Many of us will be hoping that technological advancements mean that guilt-free flying is within grasp, however, is this based in reality or merely wishful thinking?
The fact of the matter is that if we want to be able to fly without creating a negative effect on the environment we’re going to have to develop fuels that produce fewer greenhouse gases.
Unfortunately, decarbonizing the aviation industry is a complex task and there’s no clear solution in sight. A recent report by the Royal Society looked at the four most viable alternative fuel options (hydrogen, ammonia, synthetic fuels, and biofuels) that present greener alternatives to the jet fuel that is currently used by the aviation industry. Unfortunately, it concluded that none of them had the potential to replace jet fuel in the short term.
Let’s take a closer look at the different options for sustainable aviation fuel and explore why this is the case:
Hydrogen
Research has found that hydrogen could feasibly offer an alternative to jet fuel. It has the potential to reduce the climate impact of a flight by as much as 50 to 90%. However, if this is ever to become a reality, significant research and development into aircraft design, progress in the development of fuel cell technology and liquid hydrogen tanks, as well as investment into hydrogen infrastructure will be required.
If hydrogen is to be used to power a plane it would need to be stored in a cryogenic liquid state, which requires new infrastructure and significant changes to current aircraft configurations. Such redesigns to aircraft take time and money - it’s no quick fix. In fact, experts believe that it will take between ten and fifteen years to achieve these developments. This means that if sufficient investment and resources are given to the development of hydrogen fuel, we could see short-haul flights being powered by hydrogen as early as 2035.
👉Airbus has announced plans to create the first zero-emission aircraft by 2035, using hydrogen fuel cells.
Ammonia
While hydrogen might be the fuel that grabs all the headlines, there is another sustainable alternative that’s worthy of our attention: ammonia.
The second most produced chemical in the world today (it’s mainly used as fertiliser), ammonia has the potential to help decarbonise the airline industry. If ‘green ammonia’ can be produced for use as jet fuel it could potentially eliminate the production of carbon dioxide. Another added advantage of ammonia is that it has the potential to significantly reduce the formation of contrails.
However, as with hydrogen, the main challenge to the use of ammonia as a jet fuel comes from the costs associated with developing and building infrastructure to accommodate the use of the fuel on aircraft. Another issue is that even though it eliminates the production of carbon dioxide, it is still responsible for the emissions of harmful nitrous oxides.
There are currently projects underway that aim to test the feasibility of retro-fitting existing aircraft to accommodate for the use of ammonia as a jet fuel. It is hoped that proof of concept may be available as early as mid 2023.
Synthetic fuels
The long life cycles of aircraft and the time frames involved when it comes to developing aircraft engines add an extra layer of complexity when it comes to transitioning to low-carbon technologies. Fuels such as hydrogen offer potential green alternatives to the current carbon-intensive jet fuels, however, huge investment is required to develop technology allowing them to be used safely and effectively on an aircraft. This means that realistically if the aviation industry is to come to rely on hydrogen fuel, the transition will be a slow and gradual shift that is likely to take fifteen to twenty years.
Therefore if we want to reduce emissions in the short term we need to look at the viability of synthetic fuels that are compatible with existing technology, infrastructure, and regulations. These types of fuels are known as ‘drop-in’ fuels as they can simply be dropped into the existing aircraft systems.
Synthetic fuels, when produced using renewable energy, offer a carbon-neutral solution. It seems like a great solution, so why don’t we use these fuels more extensively?
Existing regulations allow for a 50/50 blend of synthetic fuels with conventional aircraft jet fuel. However, this ratio actually acts as a barrier to the development of new synthetic fuels which require a larger volume for testing.
Fuel costs are another barrier to the use of synthetic fuels as jet fuel. In order for these fuels to be competitive they need to be equal to or cheaper than conventional jet fuel. Unfortunately, due to their complex production process, they come at a higher cost. For example, synthetic fuel can be as much as 8 times more expensive than conventional jet fuel.
Biofuels
Some airlines currently use small amounts of biofuels as part of their fuel mix. Heathrow Airport in London is the largest user of biofuels globally, and uses 0.5% of their fuel supply, which is obviously an incredibly low percentage. So what are the barriers to using this fuel as a greener alternative to traditional jet fuels?
Biofuel is largely made from crops and the production of crops isn’t without its own environmental issues; agriculture is the leading source of pollution in many countries and is also responsible for the production of carbon emissions.
Another problem with biofuel is that it requires huge areas of land for growth. If we were to produce enough to supply the UK aviation industry for example, half of the UK’s farming land would need to be dedicated to growing crops solely for this purpose.
The future of the aviation industry
What’s evident is that as it stands there is no perfect solution to sustainable aviation fuel. Any new aviation fuel needs to be viable, safe, and suitable for use on long-haul flights and none of the current alternatives are without their challenges.
However, on a more positive note, experts believe that the long term outlook for the use of sustainable aviation fuels is promising. As countries and industries around the world become committed to the 2050 net zero target, increasing amounts of investment mean that new technology and solutions are likely to be developed.
While completely green options will take longer periods of time to develop and integrate into the airline industry, emissions in the short term can be reduced through the increased uptake of synthetic fuels and biofuels. Governments and industries are crucial if this is to be achieved; they need to refocus their efforts when it comes to decarbonising the aviation industry and facilitate the investment needed to develop innovative solutions.
What can we do in the meantime?
Since there is no immediate solution to decarbonising the aviation industry, individuals and companies must consider how they can contribute to reducing airline emissions in the short term. Let’s explore a few of these options below:
- Take other forms of transport, especially if it’s a short haul flight. Trains and buses are the lowest emitters when it comes to long distance forms of travel. A return flight between Paris and London for example produces 111.5 kg of carbon, while taking the Eurostar produces only 22.2 kg.
- Buy carbon offsets, or fly with airlines that have carbon offset programs. Carbon offsets offer a way to balance out the carbon emissions from your activities by investing in projects that work to reduce greenhouse gas emissions. This is often achieved through projects that plant trees for example. However, it should be noted that while beneficial, this is not a true solution: you simply shift the burden elsewhere, which is why it’s important to also take steps to reduce your carbon emissions.
- Take part in meetings and conferences virtually. This one in particular is aimed at businesses. Companies need to consider whether the business trip is necessary or not - can the meeting be carried out easily over skype for example? The reality is that physical attendance is often not crucial.
- Select economy over business class. Business class seats are more carbon intensive simply because the seats occupy more space on the aircraft. More people are able to sit in the economy section which makes them a less carbon intensive option.
What about Greenly?
At Greenly we can help you to assess your company’s carbon footprint, and then give you the tools you need to cut down on emissions. Why not request a free demo with one of our experts - no obligation or commitment required.
If you’d like to learn more about a specific industry, Greenly can help by providing an in-depth industry study, created by our climate scientists.
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