CO2 turned into fuel: Japan’s scientists convert captured carbon into green fuel

Researchers at Tokyo Metropolitan University have developed a new type of electrochemical cell that can effectively convert a bicarbonate solution—a product derived from captured carbon—into a formate solution, which is a potent source of green fuel.

It could be considered a major development in carbon capture and utilization technology.

This innovation overcomes significant challenges in reactive carbon capture (RCC) and demonstrates performance levels similar to those of traditional gas-fed methods, which are usually more energy-intensive.

“Carbon capture and utilization to convert atmospheric CO2 into useful chemicals and fuels is essential for achieving a carbon-neutral or negative emission future,” said the researchers in the study .

Challenge of carbon utilization

Notably, carbon capture technology has become an essential part of global efforts to reduce carbon emissions and combat climate change.

“But the important question of what we do with the captured carbon dioxide remains an open challenge. Do we simply push it underground, or is there more to it?” added the researchers.

Many scientists have proposed a promising approach that involves using electrochemical cells to convert carbon dioxide into formate, a substance that can generate power in fuel cells.

However, this approach faces some challenges as well. “A significant roadblock is the need for pure carbon dioxide: pressurizing carbon dioxide can be highly energy intensive,” the researchers explained in a press release .

A potential solution

The researchers believe reactive carbon capture could be an apt alternative solution in this context.

“Enter reactive carbon capture, where carbon dioxide dissolved in alkaline solutions, like bicarbonate solutions, can be directly used to create formate ions without the losses associated with providing pure gas,” they highlighted.

This method eliminates the need for pure CO2 and simplifies the conversion process.

However, designing an electrochemical cell that can selectively produce formate ions from bicarbonate, while minimizing unwanted reactions, is a complex task.

Innovative cell design

The research team has addressed this challenge by creating an innovative electrochemical cell that overcomes the primary issues in reactive carbon capture.

“In the new cell, electrodes made of catalytic material are separated from a polymer electrolyte membrane by a porous membrane made of cellulose ester,” highlighted the press release.

In this setup, hydrogen ions are generated at one electrode and move through the electrolyte membrane to the porous layer, where they react with bicarbonate ions to produce carbon dioxide within the pores.

“The gas is then converted to formate ions at the other electrode, also in contact with the porous membrane,” remarked the researchers.

Promising results and future outlook

The team claimed that the results were notable, with the new cell achieving an 85% faradaic efficiency at high currents. It means that 85% of the electrons are transformed into formate, outperforming existing designs.

Additionally, the cell remains stable for over 30 hours, achieving a nearly complete conversion of bicarbonate to formate. After removing water, the end product is a solid, crystalline formate fuel ready for use.

“The team hopes their new bicarbonate electrolyzer can be a viable option for society as it strives towards a green transformation,” concluded the press release.