The aviation industry’s carbon footprint currently makes up 12% of all transportation-related CO2 emissions. Airplanes need to use a lot of fuel to fly, which is why they pump out a ton of climate-warming carbon dioxide into the sky.
It’s a hard problem to solve because most planes can’t carry batteries big enough to run on electricity. But a team at Oxford University has found a way to make jet fuel without using oil. They reverse-engineered fuel from carbon dioxide in the lab. All the chemical engineers have to do now is scale up the method. It would make air travel carbon-neutral and part of a circular economy by turning airplane emissions back into fuel.
Joshua Heyne, a University of Dayton associate professor of mechanical and chemical engineering who was not involved in the study, said, “This does look different, and it looks like it could work. Scale-up is always an issue, and there are new surprises when you go to larger scales. But in terms of a longer-term solution, the idea of a circular carbon economy is something that could be the future.”
There are other options like green hydrogen fuel, which is made using renewable power, but it would require some modifications to the aircraft design. There are also greener alternative fuels. At the San Francisco airport, they have renewable jet fuel made from recycled cooking oil. However, even though they may generate less greenhouse gas, they’re still not a zero-emissions option.
But the new CO2 jet fuel raises the possibility of conventionally powered aircraft with net-zero emissions. The process uses a new iron-based catalyst (chemical reaction) to revert CO2 (in liquid form) into jet fuel. Others are taking a biological route, fermenting captured emissions into a palm oil substitute that can also be refined into jet fuel.
Tiancun Xiao, an author on the study and senior research fellow at Oxford’s Department of Chemistry, said, “Climate change is accelerating, and we have huge carbon dioxide emissions. The infrastructure of hydrocarbon fuels is already there. This process could help relieve climate change and use the current carbon infrastructure for sustainable development.”
When oil or natural gas burns, their hydrocarbons turn into CO2, and in the process, water and energy are released. The Oxford experiment uses the organic combustion method to reverse the process and turn CO2 back into fossil fuel. The team’s catalyst powder is made of inexpensive ingredients and transforms the greenhouse gas in a single step. It’s even cheaper than the method used to produce hydrogen fuel because it uses less electricity.
Xiao envisions installing a jet fuel plant next to a cement or steel factory to capture its excess carbon dioxide and use it to make the fuel. Or, free-standing jet fuel plants could suck the CO2 straight out of the atmosphere using direct-air capture technology.
