Carbon-Capture Device Cuts Greenhouse Gases and Generates Electricity

Electrochemical cell turns captured carbon dioxide into electricity and a useful carbon byproduct.

This electrochemical cell turns carbon dioxide into a valuable product while producing electricity. (Image courtesy of Cornell).

This electrochemical cell turns carbon dioxide into a valuable product while producing electricity. (Image courtesy of Cornell).

A team of researchers recently developed a novel method of carbon capture, the technology of trapping carbon dioxide before it’s released into the atmosphere. The team has proposed an aluminum/carbon dioxide power cell that captures CO­2 and produces electricity as well as a useful carbon byproduct.

 

Capturing Carbon Dioxide

Currently, most carbon-capture methods trap emissions in fluids or solids which can be heated or depressurized to release the CO2. The gas is then compressed to be transported for industrial use or otherwise sequestered underground. As the team points out, these methods are far from perfect.

“One of the roadblocks to adopting current CO2 capture technology in electric power plants is that the regeneration of the fluids used for capturing CO2 utilize as much as 25 percent of the energy output of the plant,” said researcher Lynden Archer, a professor of engineering at Cornell University. “This seriously limits the commercial viability of such technology. Additionally, the captured CO2 must be transported to sites where it can be sequestered or reused, which requires new infrastructure.”

The new method proposed by the team could be a paradigm shift, according to Archer. “The fact that we’ve designed a carbon capture technology that also generates electricity is, in and of itself, important,” he said.

How much electricity are we talking about?

The team reports that their electrochemical cell can generate up to 13 ampere hours per gram of carbon, with a discharge potential around 1.4 V. According to the researchers, this amount of energy is comparable to that of the highest energy-density battery systems.

The cell works by using aluminum as the anode, and a mixture of CO­2 and O2 as the active ingredients of the cathode. The electrochemical reactions between anode and cathode sequester the CO2 and produce electricity and a carbon-carbon oxalate byproduct. Since the oxalate is widely used in pharmaceutical and other industries, it’s a valuable bonus to the electrical energy.

“A process able to convert CO2 into a more reactive molecule such as an oxalate that contains two carbons opens up a cascade of reaction processes that can be used to synthesize a variety of products,” said Archer.

The potential and capacity of the cell are compared using different gas conditions. The 80% CO2 and 20% O2 mixture (black line) obtained the best results. (Image courtesy of Science Advances.)

The potential and capacity of the cell are compared using different gas conditions. The 80% CO2 and 20% O2 mixture (black line) obtained the best results. (Image courtesy of Science Advances.)

While there are clear advantages to the team’s proposed cell, their motivation remains the same as always: reduce our carbon footprint. The team believes their research offers a significant advancement towards this goal.

“On the basis of an analysis of the overall CO2 footprint, which considers emissions associated with the production of the aluminum anode and the CO2 captured/abated by the Al/CO2-O2 electrochemical cell, we conclude that the proposed process offers an important strategy for net reduction of CO2 emissions,” wrote lead author Wajdi Al Sadat in the team’s paper.

For more on reducing our carbon footprint, read about the $20-million Carbon XPRIZE.

Written by

Michael Alba

Michael is a senior editor at engineering.com. He covers computer hardware, design software, electronics, and more. Michael holds a degree in Engineering Physics from the University of Alberta.