Excess industrial carbon dioxide can be used as a raw material for producing chemicals that are usually derived from fossil fuels, but the process used for this conversion is expensive and energy-intensive. Engineers at the University of Illinois may have now come up with a solution to convert CO2 waste into valuable resources without using as much energy.
The researchers have tested a new electrolysis technology that uses a cheap biofuel byproduct to reduce the energy consumption of the waste-to-value process by 53 percent.
Using a technique called electrochemical reduction, it is possible to convert CO2 to chemicals like ethylene for plastics. In this system, a stream of CO2 gas and a fluid electrolyte move through an electrolysis cell that breaks the CO2 down into molecules like ethylene on the cathode. The experts explained that the process also produces oxygen from water on the anode.
“About 90 percent of the energy required in conventional CO2 reduction is used up by the oxygen-producing, anode side of an electrolysis cell,” said study co-author Professor Paul Kenis. “But there is no big market for the excess oxygen, so 90 percent of the energy is essentially wasted.”
According to a recent National Academies Report, finding a feed material that reduces the energy to drive the anode reaction could be a strategy for greatly reducing the energy required for CO2 conversion.
The authors of the new study have proposed glycerol as an alternative to the energy-intensive oxygen-producing step. Glycerol is an organic byproduct of sugarcane biofuel production that requires less energy to oxidize.
“Our model uses the current electrical grid setup as the source of electricity to make the scenario more realistic,” said Professor Kenis. “Being able to drive CO2 conversion with already-in-place infrastructure – and not relying on the hope of the future grid being powered by 100 percent renewables – while achieving carbon neutrality or negativity could be a holy grail scenario.”
The research is published in the journal Nature Energy.
By Chrissy Sexton, Earth.com Staff Writer
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