The dawn of electric aviation is imminent, but it will be many years before the average environmentalist can fly guilt-free on an all-electric long-haul jet.
Meanwhile, scientists are trying to make the commercial planes we already own more sustainable, and one of the best ways to do that is to change the fuel they use.
Instead of carbon dioxide (CO2) into the atmosphere, researchers at the University of Oxford and the University of Cambridge in the UK have now devised a way for planes to capture this gas from the air and burn it for fuel.
Rather than creating a whole new fleet of electric planes, which would require huge leaps in battery storage technology, this new approach would allow the world to reduce its carbon footprint from flying much sooner. That is, if it turns out to work on a larger scale.
In the lab, researchers were able to capture and convert gaseous CO2 directly into jet fuel using an inexpensive iron-based catalyst.
The amount of liquid fuel produced is still far too small to power a real aircraft, but if fossil fuels can be collected from the air in a large enough volume, converted into energy with sufficient efficiency, and then can are emitted, an aircraft could theoretically fly climate neutral.
“This catalytic process provides an attractive route to not only reduce carbon dioxide emissions, but also to produce renewable and sustainable jet fuel,” the authors write.
“The recycling of carbon dioxide as a carbon source for both fuels and performance chemicals offers significant potential for both the aviation and petrochemical industry.”
Normally, when fossil fuels burn, the hydrocarbons they contain are converted into carbon dioxide and water, releasing energy. The new system essentially reverses this natural process.
By adding heat to the system, engineers were able to combine carbon dioxide with hydrogen, separated from water, to produce a few grams of liquid fuel that the authors say could work in a jet engine.
The catalyst responsible for this impressive chemical reaction is composed of iron, manganese and potassium, which are abundant earth elements easier and cheaper to prepare than many comparable candidates. The catalyst also readily combines with hydrogen and shows high selectivity to a range of hydrocarbons for jet fuel.
The result is a little bit of fuel, as well as various petrochemicals that can only be extracted from fossil fuels.
The new system is not the first, nor will it be the last, to convert our CO2 emissions into desired biofuel. In Canada, scientists have developed a huge industrial complex to capture CO2 as the trees of a forest would do to form hydrocarbon fuel.
But although a handful of studies have shown it is possible to convert atmospheric CO2 in liquid fuel, it is extremely challenging and expensive to produce more than a small amount.
The new system looks very promising, but whether it is practical or not is another matter.
“This looks different, and it looks like it could work,” said Joshua Heyne, an independent engineer not involved in the study. Wired.
“Scaling up is always a problem, and there are new surprises as you move to a larger scale. But in terms of a longer-term solution, the idea of a circular carbon economy is certainly something that could be the future.”
Some, like Heyne, are hopeful, others see ‘flying in the sky’ as just a hype. Last year, when a company in Europe announced that they were working on a way to capture CO2 From the air to power future planes, critics pointed out that the fuel produced every day allows only a five-minute flight.
Such small returns are not a solution to the climate crisis, and some environmentalists argue that our only viable option is to fly less. Especially since the reality of a circular carbon economy is still a long way off and the crisis of climate change is just around the corner.
Ultimately, it all depends on how fast we can scale up this promising technology, and the fact is, it may not be moving fast enough.
Engineers eventually want to connect their new system to established carbon emitters, such as coal-fired power, and that would of course require continued fossil fuel production. It is also very expensive and may not be attractive to businesses, even if it works.
Still, as climate change accelerates and aviation will only increase in the coming years, the team of engineers argues CO2 transposition and exploitation as “an integral and important part of greenhouse gas management and sustainable development”.
Other sustainable biofuels that rely on plants require massive amounts of arable land and don’t tackle our emissions at the same time.
“So this is the vision for the route to achieving net zero carbon emissions from aviation,” they conclude, “a focal point of a future global carbon-free aviation sector.”
We will see.
The study is published in Nature Communications.