The aeronautical industry has been looking for ways to reduce its global carbon footprint over the past decade, such as buying so-called carbon offsets — such as tree planting projects or wind farms — to offset the carbon dioxide emitted by high-flying aircraft. At the same time, the airports of San Francisco, Chicago and Los Angeles, along with a dozen in Europe, power aircraft with greener alternative fuels to help achieve carbon reduction goals.
Now, a team at Oxford University in the UK has developed an experimental process that could convert carbon dioxide (a greenhouse gas emitted by all gas combustion engines) into aircraft fuel. If successful, the process, which uses an iron-based chemical reaction, could produce “clean zero” emissions from the aircraft.
The experiment, reported today in the journal Communications on Nature, was performed in a laboratory and has yet to be reproduced on a larger scale. But the chemical engineers who designed and carried out the process hope it can change the climate game.
“Climate change is accelerating and we have huge emissions of carbon dioxide,” says Tiancun Xiao, a senior researcher in the Oxford Department of Chemistry and author of the paper. “The hydrocarbon fuel infrastructure is already there. This process could help alleviate climate change and use current carbon infrastructure for sustainable development. “
When fossil fuels such as oil or natural gas are burned, their hydrocarbons are converted to carbon dioxide and water and energy are released. This experiment reverses the process of converting carbon dioxide into fuel using something called the organic combustion method (CMO). By adding heat (350 degrees Celsius, which is 662 degrees Fahrenheit) to citric acid, hydrogen, and a catalyst of iron, manganese, and potassium to carbon dioxide, the team was able to produce liquid fuel that would work in a jet engine. The experiment was done in a stainless steel reactor and only produced a few grams of the substance.
In the lab, the carbon dioxide came from a container. But the idea of adapting the concept to the real world would be to capture large amounts of greenhouse gas from a factory or directly from the air in order to remove it from the environment. Carbon dioxide is the most common of the greenhouse gases that heats the planet and is produced by factories, cars and firewood, including forest fires and cutting and burning agriculture. Keeping it out of the atmosphere can help reduce global warming, although global carbon emissions have risen in recent decades and are on a path to warming the planet 2 degrees Celsius by the end of the century.
Xiao and colleagues say the new method would also be cheaper than existing methods that convert hydrogen and water into fuel, a process called hydrogenation, mainly because it would use less electricity. Xiao plans to install a jet fuel plant next to a steel or cement plant or a coal-fired power plant and capture its excess carbon dioxide to make the fuel. The process could also involve sucking carbon dioxide from the atmosphere, which is called direct air capture. The catalysts that do the trick are abundant in the earth and require fewer steps than other methods of synthesizing high value-added chemicals, according to the authors.
An expert who did not participate in the experiment says the concept looks promising, as long as the authors can figure out how to go from producing tiny amounts of aircraft fuel in the lab to making larger amounts on a pilot plant. “This looks different and looks like it could work,” says Joshua Heyne, an associate professor of mechanical and chemical engineering at the University of Dayton. “Enlargement is always a problem and there are new surprises when it comes to a larger scale. But when it comes to a long-term solution, the idea of a circular carbon economy is definitely something that could be the future. ”