New Zealand and Chinese scientists make breakthrough in CO2-fuel conversion process

Scientists from the University of Auckland and Huazhong University of Science and Technology in China have made a breakthrough in the process of converting carbon dioxide into fuel.

Average global concentrations of CO2, an important heat-trapping greenhouse gas, were 50 percent above pre-industrial levels for the first time in 2022, according to the World Meteorological Organisation. CO2 levels again rose in 2023, the global weather agency said.

The scientists utilised electrochemical processes to turn CO2 into formic acid, a colourless and pungent liquid that can be used as a fuel.

Project leader Dr Ziyun Wang from the University of Auckland's School of Chemical Sciences said researchers had long wanted to convert CO2 into a form that was useful but were frequently hampered by stability problems.

However, scientists have found that formic acid produced from CO2 can continuously power a system for more than 5000 hours without any instability issues, Wang said.

All that remained was for the process to be industrialised, he said.

The discovery was featured in science journal Nature earlier this year.

"The biggest problem with cars now is that fossil fuels are not renewable," Wang said. "If we make fuel renewable, maybe we can solve all the problems? We can keep the cars and the petrol stations, but it's just that the fuel is renewable.

"Based on this idea, we can solve the problem by burning fuel into CO2 and then converting CO2 back into (another form of) fuel. Instead of turning all cars into battery-powered ones and having to deal with old batteries in 10 years, we might as well try to convert CO2 into fuel."

He said the move was significant for New Zealand, which is far from fuel-producing regions such as the Middle East and, as such, is dependent on supply chains.

On the flip side, New Zealand has produced more than 75 million tonnes of CO2-equivalent units of gross greenhouse gas emissions annually since 2000, according to Stats NZ.

"We feel that CO2 is ... a threat to climate change, but why can't it be an asset?" Wang said.

As part of the process, the scientists managed to extract lead from used lead-acid batteries and convert the element into a catalyst that helped turn carbon dioxide into formic acid.

Wang said the world would likely find it difficult to recycle an ever-growing volume of electric car batteries, but his discovery offered a possible solution.

"The best way is to turn waste into a treasure," Wang said.

Wang and the team conducted their experiments with pure CO2 and wanted to explore the possibility of capturing CO2 directly from the air or a flue system, subsequently using their system to produce formic acid or other forms of fuel.

"If this can happen ... you could capture carbon dioxide at home when you need to drive, convert it into fuel and then use it to power your car," Wang said.

Postdoctoral researcher Dr Yu Mao, who also participated in the project, said the team was also exploring how to turn CO2 into other fuels, including ethylene or ethanol.

Wang said the laboratory had started work with a New Zealand company, hoping to continue to explore how to better utilise CO2.

Wang hoped his team's breakthrough inspired other researchers to study carbon dioxide.

"If the problem of CO2 can be widely recognised and reported, it may attract young people and students to dedicate themselves to this field," Wang said.

"In fact, CO2 is not a difficult problem to solve," he said. "Many people want to solve it through legislation, for example increasing carbon taxes or discussing the carbon emissions of each country. Why is CO2 a problem rather than an opportunity?"