Energy

Carbon capture system turns CO2 into electricity and hydrogen fuel

Carbon capture system turns CO...
Scientists have developed a new device that can absorb CO2 and produce electricity and hydrogen fuel
Scientists have developed a new device that can absorb CO2 and produce electricity and hydrogen fuel
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A diagram showing how the Hybrid-Na-CO2 System works
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A diagram showing how the Hybrid-Na-CO2 System works
Scientists have developed a new device that can absorb CO2 and produce electricity and hydrogen fuel
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Scientists have developed a new device that can absorb CO2 and produce electricity and hydrogen fuel

If we're going to reach the goal of keeping Earth from warming more than 1.5° C (2.7° F) this century, it's not enough to just reduce our carbon dioxide emissions – we need to actively clean it out of the atmosphere too. Inspired by the ocean's role as a natural carbon sink, researchers at Ulsan National Institute of Science and Technology (UNIST) and Georgia Tech have developed a new system that absorbs CO2 and produces electricity and useable hydrogen fuel.

The new device, which the team calls a Hybrid Na-CO2 System, is basically a big liquid battery. A sodium metal anode is placed in an organic electrolyte, while the cathode is contained in an aqueous solution. The two liquids are separated by a sodium Super Ionic Conductor (NASICON) membrane.

A diagram showing how the Hybrid-Na-CO2 System works
A diagram showing how the Hybrid-Na-CO2 System works

When CO2 is injected into the aqueous electrolyte, it reacts with the cathode, turning the solution more acidic, which in turn generates electricity and creates hydrogen. In tests, the team reported a CO2 conversion efficiency of 50 percent, and the system was stable enough to run for over 1,000 hours without causing any damage to the electrodes. Unlike other designs, it doesn't release any CO2 as a gas during normal operation – instead, the remaining half of the CO2 was recovered from the electrolyte as plain old baking soda.

"Carbon capture, utilization, and sequestration (CCUS) technologies have recently received a great deal of attention for providing a pathway in dealing with global climate change," says Professor Guntae Kim, lead researcher on the study. "The key to that technology is the easy conversion of chemically stable CO2 molecules to other materials. Our new system has solved this problem with CO2 dissolution mechanism."

This Hybrid Na-CO2 System is far from the only carbon capture system out there, but it remains to be seen whether these technologies can ever become practical enough at large scales to have much of an impact. Climeworks' direct air capture system is one of the most promising at the moment, but when it only removes 150 tons of CO2 a year (compared to the 40 billion tons released into the atmosphere annually) it feels like bailing a sinking ship with a plastic cup.

But, the team says, there's still room for improvement with every component of the new design. And the icing on the cake could be the system's ability to also produce renewable electricity and hydrogen fuel, which could be used to power hydrogen cars.

The research was published in the journal iScience.

Source: UNIST via Phys.org

9 comments
nono
Calling BS on this one.. the sodium electrode is consumed in the process getting sodium carbonate. To produce the sodium you take much more energy than u take out of this.
piperTom
Ditto what Nono said. Sodium is commercially produced by electrolysis, consuming large amounts of electricity. Even if you didn't know that (and had no access to wikipedia!), you should know that the economics wouldn't allow an energy gain from "getting rid of" CO2: outside of cement production, CO2 is produced almost exclusively to make energy. How could it then be that we could (commercially) make more energy from the CO2?!
watersworm
Great ! So welcome back coal-fired plants to produce low cost electricity... and hydrogen by "capturing" devillish CO2. Very good news for China, India, Poland, Australia and maybe Germany !
Kpar
Excellent comments, here. BTW, if one wants to "clean CO2 out of the atmosphere", one might consider planting a plant.
Douglas Bennett Rogers
The stuff coming out of those stacks (that is visible) is water aerosol. In the deserts it has a lot bigger greenhouse effect per pound than CO2. It is all about the per cent increase in path length water.
Robert in Vancouver
The obsession about getting rid of CO2 is the biggest threat to life on Earth. Current levels of CO2 are within normal variations that allow flora to grow. Without healthy thriving plants and greenery, all living things will die. The Earth is currently the greenest ever in the modern era, proven by satellite images taken ever since this was possible to do. Keep CO2 at current levels or a little higher and we will keep the Earth green. Reduce CO2 too much and we will turn the Earth into a brown dead planet.
Ewen Fagan
Nono and PiperTom are right on the money. This a misleading article in that the sodium metal consumption is not mentioned in fact on the contrary they say no damage to electrodes. I suspect the research is funded buy the coal industry or they are seeking a grant. More a sales pitch than a serious technical article.
ljaques
I think this boils down to a large petrochemical industry wanting to keep relevant. Keep ICE cars on the road, gas stations operating, drivers moving hydrogen instead of gasoline/diesel, etc. The CO2 removal brings in the approval of the extremist Left who worship the Church of Global Warming/Climate Change/Tipping Point. Everyone's happy. Well, except all of us who drive these expensive things. Give me a mini-Epickup with a 500 mile battery and I'll be in heaven.
john75
Even if the sodium electrode is long lived I shudder to think they'd try to store hydrogen gas when it's the single hardest gas to contain and any amount that leaks is 50 times as potent a greenhouse gas as CO2. Leaks. Always. Happen. Even methane is 4 times worse than CO2 but would be an obvious way to both leverage the usable output and the existing petrochemical supply inferstructure. It seems like the Elephant in the Room but our power grid is nowhere near able to sustain the demand if all our cars and trucks were plug in EVs. And it's not happening in less than 50 years with or without an Apollo Program type commitment. We're going to be relying on chemical fuels for a long time to come, the key will be sourcing as much as possible from renewable sources as we ramp up carbon sequestration to meaningful levels