Carbon capture fuel cell lowers greenhouse gases produces electricity

An oxygen-assisted power cell that uses electrochemical reactions to sequester carbon dioxide and produce electricity could help to alleviate the negative impact of greenhouse gases.

Using aluminium as the anode, the cell uses mixed streams of carbon dioxide and oxygen as the active ingredients of the cathode.

The electrochemical reactions between the anode and the cathode are capable of sequestering the carbon dioxide into carbon-rich compounds while also producing electricity.

In most current carbon-capture models, the carbon is captured in fluids or solids, which are then heated or depressurized to release the carbon dioxide.

The concentrated gas must then be compressed and transported to industries able to reuse it, or sequestered underground.

The UK government has recently been criticised for cancelling its support for carbon capture, which is seen by proponents as essential for mitigating the impact of electricity production on climate change. 

"The fact that we've designed a carbon capture technology that also generates electricity is, in and of itself, important," said Cornell University’s professor Lynden Archer who worked on the project.

"One of the roadblocks to adopting current carbon dioxide capture technology in electric power plants is that the regeneration of the fluids used for capturing carbon dioxide utilise as much as 25 percent of the energy output of the plant.

“This seriously limits commercial viability of such technology. Additionally, the captured carbon dioxide must be transported to sites where it can be sequestered or reused, which requires new infrastructure."

The group reported that their electrochemical cell generated 13 ampere hours per gram of porous carbon (as the cathode) at a discharge potential of around 1.4 volts. The energy produced by the cell is comparable to that produced by the highest energy-density battery systems.

In addition, the process produces what is known as ‘superoxide intermediates’ a carbon-dioxide based compound that is widely used in many industries, including pharmaceutical, fibre and metal smelting.

Al Sadat, who worked on on-board carbon capture vehicles at Saudi Aramco, said this technology is not limited to power-plant applications. "It fits really well with on-board capture in vehicles," he said, "especially if you think of an internal combustion engine and an auxiliary system that relies on electrical power."

Sadat believes one of the advantages of the fuel cell is that aluminium is plentiful, safer than other high-energy density metals and lower in cost than other potential materials (lithium, sodium) while having comparable energy density to lithium.

He said many aluminium plants are already incorporating some sort of power-generation facility into their operations, so this technology could assist in both power generation and reducing carbon emissions.

A current drawback of this technology is that the electrolyte, the liquid connecting the anode to the cathode, is extremely sensitive to water. The team is working to address the performance of electrochemical systems and the use of electrolytes that are less water-sensitive.

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