7 ms·

Liquid Gallium Shown to Break Down Carbon Dioxide – Sci-News.com

54 points by mrfusion 5y ago

vegetablepotpie 5y ago
> They [scientists] estimate this [process] equates to a cost of around $100 per ton of carbon dioxide. Way above the ~$18 price tag California puts on a ton of carbon. But this method has the benefit that it returns oxygen to the atmosphere instead of locking it away, bonded to carbon, for eons. Perhaps added incentives can be made to methods that not only sequester carbon, but also return oxygen back to the the atmosphere.
- pengaru 5y ago
  It also has the benefit of apparently producing a high purity carbon sheet having existing industrial applications. The cost could be offset substantially if they're producing inputs for high margin industries like carbon fiber products...
- unmole 5y ago
  Why is returning oxygen to the atmosphere desirable?
  - robbedpeter 5y ago
    Breathing and aerobic bacteria and oxidizing reactions all throughout the chemistry of life. This is a great line of thought, though - would increasing local oxygen concentrations possibly result in negative outcomes elsewhere? Acid rain or maybe ozone increases, etc?
    - unmole 5y ago
      > Breathing and aerobic bacteria and oxidizing reactions all throughout the chemistry of life. None of these are in any way constrained by the concentration of oxygen. The carbon dioxide in the atmosphere is 0.04%. The amount of captured carbon that will be broken down through technology will be a fraction of this. It is unlikely to change the concentration of oxygen in anyway.
- robbedpeter 5y ago
  Just to clarify, it's about $100 for 500 lbs of carbon, so $400 per ton of carbon flakes.
- mrfusion 5y ago
  You could sell the oxygen too which would bring down the price.
throwaway81523 5y ago
> The scientists obtained 92% efficiency at the remarkably low input energy of 230 kWh for the capture and conversion of a ton of carbon dioxide. Until all the coal burning power plants are shut down, that 230kwh is almost certainly better used displacing some coal. If it didn't already come from coal.
- robbedpeter 5y ago
  https://www.eia.gov/tools/faqs/faq.php?id=667&t=2 https://www.eia.gov/tools/faqs/faq.php?id=667&t=2 1.13 kw/h per pound of coal burned. 260 lbs of coal enables processing of 1 ton of co2, of which about 500 lbs is captured as carbon flakes. You could burn coal, producing 525 lbs of co2 for the energy needed to process 1 ton of co2 in total, so you end up capturing 375lbs more carbon than is produced. 125lbs of the carbon flakes come from the coal, the other 50 lbs of carbon in the coal is lost as byproducts and inefficiency. So running this process, even on pure coal, sequesters 2.75 to 3 times as much carbon as it produces as co2.
gp 5y ago
In the paper the team reports roughly 50-80% estimated mechanical efficiency, 92% conversion of CO2 by mass in a 27cm / 330ml column, and ~230kw*hr/ton of CO2 energy input. They used 6%-20% CO2 mixtures with balance nitrogen and some water to try and approximate different exhausts including flue gas. This seems like a groundbreaking achievement. The only thing that wasn’t clear to me was the size of reactor they expect to be required to achieve meaningful throughput, and the amount of HCl replenishment required, if any, to maintain catalytic performance. This paper gives me a lot of hope.
- robbedpeter 5y ago
  It's talked about as a catalytic reaction, and the solvent isn't consumed - you get o2, nitrogen, and carbon flakes (which can be further sonicated in a detergent mixture to produce graphene flakes. ) They estimated $100 cost for ~500 lbs of carbon. To put things in context, there's about a trillion tons of "excess" co2 in the atmosphere. That means you're going to need to produce 280 million tons of carbon to reset to 1970 levels. $400 per ton means $1,120,000,000 , or $1.12 trillion. Assume economies of scale, improved efficiency, secondary markets, and you could reduce the effective cost by 80%, so maybe $250 billion could solve co2 climate impact. Spread that out over all vehicles, power plants, businesses, and so on, and that seems achievable over a decade. Spread over global scales on a sound 50 year plan, and people wouldn't even notice any economic impact. Now what if you can tweak the chemistry and produce methane or ethanol or propane? Pure carbon feedstock has to have more uses, so it might be a net producer of value, as opposed to a fundamental cost. Pretty exciting to think about.
  - zamalek 5y ago
    > $400 per ton means $1,120,000,000 , or $1.12 trillion. That's practically nothing. This is very hope inspiring: when politics eventually catches up to science we may actually have the tools to do something in time.
  - mrfusion 5y ago
    Even maintaining our current co2 levels would be pretty amazing. And that could be much cheaper.
mikewarot 5y ago
There must be an error in the math somewhere... This could greatly improve the efficiency of burning coal. Let's say you burn a ton of coal, (assume pure carbon for this example) getting 2460 kWh of power, per ref: [1] You then put the resultant 3 2/3 ton of CO2 through this process, at a cost of 843 kWh, recovering 920 kg of carbon. You've now consumed net 80 kg of carbon, generated 2460-843 --> 1617 kWh of electricity, for a net of 20,212 kWh/ton of Carbon burned. This page [1] says a ton of coal gives 2460 kWh of electricity 1 - https://www.mcginley.co.uk/news/how-much-of-each-energy-source-does-it-take-to-power-your-home/bp254/#:~:text=There%20is%202%2C460%20kWh%20of%20electricity%20generated%20per%20ton%20of%20coal https://www.mcginley.co.uk/news/how-much-of-each-energy-sour....
- robbedpeter 5y ago
  One thing missing is the energy cost of removing/drying the carbon flakes from the system, then moving themfor combustion. In a closed loop, you could create a cycle that consumed co2 and reconstituted it by burning and reproducing co2, but it would taper off. Yes, you could burn the carbon flakes to produce more energy than the system consumes, but you'll need more oxygen from the environment to maintain the reaction. At 92% efficiency, you'd run out of oxygen to maintain combustion after a dozen cycles or so, in a closed system. With an endless amount of atmospheric co2, the picture changes. 2460 kwh, at 12 cents per kwh, translates to $295 of electricity per ton. It optimally produces twice as much as it consumes. Maybe a Stirling engine that uses a belt feeder, with the flakes skimmed from the catalytic reaction chamber onto the belt, drying in the heat of combustion, then dropped into the burner, and the exhaust bubbled back into the solvent. Then it could deposit the excess flakes while producing power by directly consuming co2? This is pretty phenomenal, edging into the "too good to be true" domain. Anyway, pointing out that pure carbon can be burned is good thinking.
  - zinekeller 5y ago
    ... it can be buried though (just not in oceans because it will just be turned back into CO2) or even reused in carbon-composite materials.
  - 5y ago
rich_sasha 5y ago
I’m trying to understand how this isn’t a perpetual motion machine. I can burn some coal, turn C and O2 into energy and CO2, then use a fraction of the energy to split it back into C and O2 and be left with some energy still (quite a bit apparently). So I can repeat as much as I like. What am I missing?
- zamalek 5y ago
  The incredible inefficiency of the combustion engine, and this process is 92% efficient (not 100%).
- hexane360 5y ago
  From the original paper, the end result is "highly oxidized carbon", "akin to that of slightly crystalline graphene oxide". So they're not claiming to split CO2 into C and O2, but more to vitrify the carbon oxide in a solid phase. This, presumably, takes significantly less energy than reducing the carbon, and you can't burn the output product.
  - rich_sasha 5y ago
    OK, so in layman's terms, they are putting CO2 into a solid. This sounds nice. What exactly is this? I tried googling around, but the only hits I get are for dry ice, which this clearly isn't. I guess the key concern with CO2 is that it gets vented into the atmosphere. If we could solidify it, we could stick it back into the mines and that's one problem off our list.
solarkraft 5y ago
Maybe this is the case with all processes, but it looks so simple that it has to have been tried before. How certain is it that this actually works?

54 points by mrfusion 5y ago

> They [scientists] estimate this [process] equates to a cost of around $100 per ton of carbon dioxide. Way above the ~$18 price tag California puts on a ton of carbon. But this method has the benefit that it returns oxygen to the atmosphere instead of locking it away, bonded to carbon, for eons. Perhaps added incentives can be made to methods that not only sequester carbon, but also return oxygen back to the the atmosphere.

pengaru 5y ago
It also has the benefit of apparently producing a high purity carbon sheet having existing industrial applications. The cost could be offset substantially if they're producing inputs for high margin industries like carbon fiber products...
unmole 5y ago
Why is returning oxygen to the atmosphere desirable?
- robbedpeter 5y ago
  Breathing and aerobic bacteria and oxidizing reactions all throughout the chemistry of life. This is a great line of thought, though - would increasing local oxygen concentrations possibly result in negative outcomes elsewhere? Acid rain or maybe ozone increases, etc?
  - unmole 5y ago
    > Breathing and aerobic bacteria and oxidizing reactions all throughout the chemistry of life. None of these are in any way constrained by the concentration of oxygen. The carbon dioxide in the atmosphere is 0.04%. The amount of captured carbon that will be broken down through technology will be a fraction of this. It is unlikely to change the concentration of oxygen in anyway.
robbedpeter 5y ago
Just to clarify, it's about $100 for 500 lbs of carbon, so $400 per ton of carbon flakes.
mrfusion 5y ago
You could sell the oxygen too which would bring down the price.

throwaway81523 5y ago

> The scientists obtained 92% efficiency at the remarkably low input energy of 230 kWh for the capture and conversion of a ton of carbon dioxide. Until all the coal burning power plants are shut down, that 230kwh is almost certainly better used displacing some coal. If it didn't already come from coal.

robbedpeter 5y ago
https://www.eia.gov/tools/faqs/faq.php?id=667&t=2 https://www.eia.gov/tools/faqs/faq.php?id=667&t=2 1.13 kw/h per pound of coal burned. 260 lbs of coal enables processing of 1 ton of co2, of which about 500 lbs is captured as carbon flakes. You could burn coal, producing 525 lbs of co2 for the energy needed to process 1 ton of co2 in total, so you end up capturing 375lbs more carbon than is produced. 125lbs of the carbon flakes come from the coal, the other 50 lbs of carbon in the coal is lost as byproducts and inefficiency. So running this process, even on pure coal, sequesters 2.75 to 3 times as much carbon as it produces as co2.

gp 5y ago

In the paper the team reports roughly 50-80% estimated mechanical efficiency, 92% conversion of CO2 by mass in a 27cm / 330ml column, and ~230kw*hr/ton of CO2 energy input. They used 6%-20% CO2 mixtures with balance nitrogen and some water to try and approximate different exhausts including flue gas. This seems like a groundbreaking achievement. The only thing that wasn’t clear to me was the size of reactor they expect to be required to achieve meaningful throughput, and the amount of HCl replenishment required, if any, to maintain catalytic performance. This paper gives me a lot of hope.

robbedpeter 5y ago
It's talked about as a catalytic reaction, and the solvent isn't consumed - you get o2, nitrogen, and carbon flakes (which can be further sonicated in a detergent mixture to produce graphene flakes. ) They estimated $100 cost for ~500 lbs of carbon. To put things in context, there's about a trillion tons of "excess" co2 in the atmosphere. That means you're going to need to produce 280 million tons of carbon to reset to 1970 levels. $400 per ton means $1,120,000,000 , or $1.12 trillion. Assume economies of scale, improved efficiency, secondary markets, and you could reduce the effective cost by 80%, so maybe $250 billion could solve co2 climate impact. Spread that out over all vehicles, power plants, businesses, and so on, and that seems achievable over a decade. Spread over global scales on a sound 50 year plan, and people wouldn't even notice any economic impact. Now what if you can tweak the chemistry and produce methane or ethanol or propane? Pure carbon feedstock has to have more uses, so it might be a net producer of value, as opposed to a fundamental cost. Pretty exciting to think about.
- zamalek 5y ago
  > $400 per ton means $1,120,000,000 , or $1.12 trillion. That's practically nothing. This is very hope inspiring: when politics eventually catches up to science we may actually have the tools to do something in time.
- mrfusion 5y ago
  Even maintaining our current co2 levels would be pretty amazing. And that could be much cheaper.

mikewarot 5y ago

There must be an error in the math somewhere... This could greatly improve the efficiency of burning coal. Let's say you burn a ton of coal, (assume pure carbon for this example) getting 2460 kWh of power, per ref: [1] You then put the resultant 3 2/3 ton of CO2 through this process, at a cost of 843 kWh, recovering 920 kg of carbon. You've now consumed net 80 kg of carbon, generated 2460-843 --> 1617 kWh of electricity, for a net of 20,212 kWh/ton of Carbon burned. This page [1] says a ton of coal gives 2460 kWh of electricity 1 - https://www.mcginley.co.uk/news/how-much-of-each-energy-source-does-it-take-to-power-your-home/bp254/#:~:text=There%20is%202%2C460%20kWh%20of%20electricity%20generated%20per%20ton%20of%20coal https://www.mcginley.co.uk/news/how-much-of-each-energy-sour....

robbedpeter 5y ago
One thing missing is the energy cost of removing/drying the carbon flakes from the system, then moving themfor combustion. In a closed loop, you could create a cycle that consumed co2 and reconstituted it by burning and reproducing co2, but it would taper off. Yes, you could burn the carbon flakes to produce more energy than the system consumes, but you'll need more oxygen from the environment to maintain the reaction. At 92% efficiency, you'd run out of oxygen to maintain combustion after a dozen cycles or so, in a closed system. With an endless amount of atmospheric co2, the picture changes. 2460 kwh, at 12 cents per kwh, translates to $295 of electricity per ton. It optimally produces twice as much as it consumes. Maybe a Stirling engine that uses a belt feeder, with the flakes skimmed from the catalytic reaction chamber onto the belt, drying in the heat of combustion, then dropped into the burner, and the exhaust bubbled back into the solvent. Then it could deposit the excess flakes while producing power by directly consuming co2? This is pretty phenomenal, edging into the "too good to be true" domain. Anyway, pointing out that pure carbon can be burned is good thinking.
- zinekeller 5y ago
  ... it can be buried though (just not in oceans because it will just be turned back into CO2) or even reused in carbon-composite materials.
- 5y ago

rich_sasha 5y ago

I’m trying to understand how this isn’t a perpetual motion machine. I can burn some coal, turn C and O2 into energy and CO2, then use a fraction of the energy to split it back into C and O2 and be left with some energy still (quite a bit apparently). So I can repeat as much as I like. What am I missing?

zamalek 5y ago
The incredible inefficiency of the combustion engine, and this process is 92% efficient (not 100%).
hexane360 5y ago
From the original paper, the end result is "highly oxidized carbon", "akin to that of slightly crystalline graphene oxide". So they're not claiming to split CO2 into C and O2, but more to vitrify the carbon oxide in a solid phase. This, presumably, takes significantly less energy than reducing the carbon, and you can't burn the output product.
- rich_sasha 5y ago
  OK, so in layman's terms, they are putting CO2 into a solid. This sounds nice. What exactly is this? I tried googling around, but the only hits I get are for dry ice, which this clearly isn't. I guess the key concern with CO2 is that it gets vented into the atmosphere. If we could solidify it, we could stick it back into the mines and that's one problem off our list.

solarkraft 5y ago

Maybe this is the case with all processes, but it looks so simple that it has to have been tried before. How certain is it that this actually works?