Engineers make Martian fuel using CO2 reactor

Chemical engineers from the University of Cincinnati are developing new approaches to converting greenhouse gases to fuel. This could not only help address climate change but also, in the further future, help astronauts return home from Mars.

Professor Jingjie Wu and his students used a carbon catalyst in a reactor to convert carbon dioxide into methane. This process, the Sabatier reaction, is used on the International Space Station to 'scrub' CO2 from the air its inhabitants breathe and generate rocket fuel to keep the station in stable orbit.

Wu, who began by studying fuel cells for electric vehicles, started looking at CO2 conversion in his lab 10 years ago.

“I realised that greenhouse gases were going to be a big issue in society,” he said. “A lot of countries realised that carbon dioxide is a big issue for the sustainable development of our society. That’s why I think we need to achieve carbon neutrality. [US decarbonisation targets] mean we’ll have to recycle carbon dioxide.”

Wu and his students experimented with catalysts such as graphene quantum dots (layers of carbon on the nanoscale) for increasing the yield of methane. He hopes the process could lead to start-ups commercialising the technique for fuel production; the process is 100 times more productive than it was just 10 years ago. Wu’s students are using different catalysts to produce not only methane but ethylene, which is a crucial ingredient in the manufacture of plastics, rubber, synthetic clothing, and other products.

Synthesising fuel from CO2 becomes even more commercially viable when coupled with renewable energy that cannot be stored: “Right now, we have excess green energy that we just throw away. We can store this excess renewable energy in chemicals,” he said.

The conversion process is also scalable for use in power plants that generate CO2, and can take place at the point of excess CO2 production.

Wu said that advances in fuel production from CO2 make him confident that humans will reach Mars in his lifetime. The Martian atmosphere is composed almost entirely of CO2. If astronauts destined for Mars could make what they need to return home on the surface, they could halve the amount of fuel they would need to take with them. Wu said: “It’s like a gas station on Mars. You could easily pump carbon dioxide through this reactor and produce methane for a rocket.”

“Right now, if you want to come back from Mars, you would need to bring twice as much fuel, which is very heavy. And in the future, you’ll need other fuels. So, we can produce methanol from CO2 and use them to produce other downstream materials. Then maybe one day we could live on Mars.”

The study is published in Nature Communications, with collaborators from Rice University, Shanghai University, and East China University of Science and Technology.

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