Edited by Sky Ye.
Climate Change
A single passenger taking a direct flight from Kuala Lumpur to London is estimated to emit 600 kg of carbon dioxide gas into our atmosphere(1). That’s equivalent to the weight of three lions' worth of greenhouse gases, a pollutant that traps heat in our atmosphere causing climate change. This remains one of the most prominent problems in our global decarbonisation mission. Already having suffered its biggest economic crisis due to the pandemic, the aviation industry now has its eyes on another more pressing challenge — turning green.
Unlike land vehicles, it’s not as easy to strap a battery onto an Airbus A380 and call it a day. A huge and heavy battery would be needed to power the intricate engines and the privilege of long-distance flights will be long gone. The community has looked into two innovative approaches to combat this issue.
The Dream Energy Source
To discover an energy-dense power source, researchers looked at the fuel that powers the sun, hydrogen! This element can provide tremendous amounts of energy with little weight and volume. Although it’s one of the most abundant elements in nature, it doesn’t usually exist in an inert form and has to be produced through industrial processes(2). The different ways of producing it have introduced three types of hydrogen sourced energy: green hydrogen, brown hydrogen and blue hydrogen(3).
The production of brown & blue hydrogen emits CO₂ which is counter-productive to our mission(3), so the ideal route is green hydrogen. Let's dive deeper into this colourless gas in order to understand its properties.
Green Hydrogen
We’ve all been in a science class where we’ve witnessed the process of electrolysis. With just two carbon rods, water decomposes into two gases in a 2:1 ratio. And of course, you guessed it! Green hydrogen is produced through large-scale electrolysis(2). However, the problem with this is that it requires a huge amount of electricity. For green hydrogen to truly be green, the electricity used has to be sourced from a renewable energy source such as solar and nuclear to ensure no CO₂ is emitted during the process of sourcing this hydrogen.
The amount of energy invested as electricity is equal to the amount of energy possessed by hydrogen as the end product, making hydrogen more of an energy carrier than an energy source. However, its high fuel density and environmental friendliness have made it the official future of aviation(4).
More Hydrogen Problems
Sure, it sounds perfect in theory. However, hydrogen is a gas while traditional jet fuel is a liquid. Considering the difference in weight, storage systems, fuelling procedures and the different engine mechanisms required, it’s impossible to simply start refuelling our aircrafts with hydrogen. Instead a completely new aircraft has to be designed and adapted(4). Airbus(a huge aircraft manufacturer) is amongst those at the forefront of research in hydrogen powered aircrafts with many futuristic designs(5).
With all the trials and errors involved in redesigning aircrafts, combined with the current economic state of airlines all across the globe; it is estimated that hydrogen commercial flights will take decades before becoming a reality(4).
Today
But carbon emissions are today's issue. It will be too late to wait for hydrogen powered solutions. Thus, the industry has found another alternative, Sustainable Aviation Fuel (SAF). Would you have ever imagined a day when plants could power jumbo jets? That became a reality with SAF where plants, waste, algae are repurposed into biofuel which is identical to the normal earth-destroying jet fuel. This new alternative reduces carbon emissions by a staggering 80%(6). Recently, Neste provided SAF with a commercial Malaysia Airlines flight from Kuala Lumpur to Singapore, and many more are happening around the world with companies like Shell joining the SAF race.
SAF is convenient, providing a drop in fuel, which means they can replace jet fuel without altering the process or mechanisms required. The catch is that this new innovation costs almost three times the price of normal jet fuel which is hard to swallow for the economically disadvantaged airlines and passengers looking to fly low-cost(4).
Looking into the Future
Hydrogen is exciting! It will greatly reduce aviation’s impact on climate change and allow us to finally fly green. However, it’s a long and rough road ahead that we need to keep exploring. While the hydrogen future is still being developed, SAF will help us bring down our CO₂ emissions.
References:
Google. (2022). Google Flights. https://www.google.com/travel/unsupported?tfs=CBwQAhojagwIAhIIL20vMDQ5ZDESCjIwMjMtMDEtMTdyBwgBEgNMSFJwAYIBCwj___________8BQAFIAZgBAg&tfu=EgIIAQ&ucpp=CpIBaHR0cHM6Ly93d3cuZ29vZ2xlLmNvbS90cmF2ZWwvZmxpZ2h0cy9zZWFyY2g_dGZzPUNCd1FBaG9qYWd3SUFoSUlMMjB2TURRNVpERVNDakl3TWpNdE1ERXRNVGR5QndnQkVnTk1TRkp3QVlJQkN3al9fX19fX19fX19fOEJRQUZJQVpnQkFnJnRmdT1FZ0lJQVE
Hydrogen: A Clean, Flexible Energy Carrier. (2017). Energy.Gov. https://www.energy.gov/eere/articles/hydrogen-clean-flexible-energy-carrier#:%7E:text=Hydrogen%20is%20an%20energy%20carrier,electricity%2C%20or%20power%20and%20heat
Blue Hydrogen. The greatest fossil fuel scam in history? (2021, September 5). YouTube. https://www.youtube.com/watch?v=2EA4tDYwNYo
Can flying go green? | The Economist. (2021, February 10). YouTube. https://www.youtube.com/watch?v=ldhilLgVML0
Hydrogen. (2021, July 1). Airbus. https://www.airbus.com/en/innovation/zero-emission/hydrogen#:%7E:text=At%20Airbus%2C%20we%20believe%20hydrogen,aircraft%20to%20market%20by%202035.
Air bp. (2022). What is sustainable aviation fuel (SAF) and why is it important? | News and views. https://www.bp.com/en/global/air-bp/news-and-views/views/what-is-sustainable-aviation-fuel-saf-and-why-is-it-important.html