10 ms·

1. The solvent in carbon capture runs in a closed loop. You typically heat it, and it releases the CO2 so you can compress it and inject it below ground. 2. Yo

1. The solvent in carbon capture runs in a closed loop. You typically heat it, and it releases the CO2 so you can compress it and inject it below ground. 2. You don't necessarily need a depleted natural gas reservoir to inject CO2 subsurface (though they sure are convenient) and there is plenty of room for CO2 subsurface. It also doesn't creep to the surface on any meaningful timescale. 3. How do we transport it there? Pipelines. I feel like CO2 sequestration is second only to nuclear in the amount of unfounded concerns. There's one very well founded concern directly in the article - they estimate $50 per tonne of CO2 just to capture, let alone to store. My experience on a 2009 carbon capture plant design was that approx $100 per tonne of CO2 was the lowest carbon price that would really make carbon sequestration highly attractive and widespread. I also happen to think a $100 per tonne carbon price is not such a bad idea. But it is possible that other technologies would beat carbon sequestration at that carbon price point. I don't know.

GekkePrutser 6y ago
Ok closed loop sounds better, the article didn't clarify this. But the compression itself and the heating will cost significant energy too, don't forget this. But consider for a moment how much coal and oil we've been digging up since the industrial age. CO2 is much less dense once it's uncontained underground. It won't stay liquid at that pressure. In that case we'll need to have underground space of a size of many times the space that all that coal and oil took up, due to the lower density. Just pumping it there, forcing it underground in different spots etc will also cause significant ecological disruption. It's a lot of land we're going to be running pipelines to, drilling into to inject it, using heavy machinery etc. And if some of it does end up being released due to a mistake, it can have potentially deadly effects. Like what happened at Lake Nyos. Safety would really have to be guaranteed. I don't know, it just sounds like a solution that won't scale to the enormity of the climate problems, and rather more like big business wanting to monetise the problem itself (and also use it as an excuse to not reduce consumption). But anyway, if it does prove itself in trials I would change my mind on it.
- londons_explore 6y ago
  The little detail that injecting CO2 into gas and oil wells can help get more gas and oil out of them is the main reason companies are investing in this tech. If the government can be persuaded to pay for the research, all the better!
  - PaulHoule 6y ago
    In Texas you can find big pockets of CO2 undeground and pdople havd been driling holes into those and pumping the CO2 into oil wells. Thus the pipeline, injection, etc. are all developed. CO2 at 1200 psi will mix with oil very well and do wonders getting into pores, but to scale up storage there are not enough oil wells and we'd probably store in saline aquifers.
- DennisP 6y ago
  One great idea for storage is underground basalt formations. Inject CO2, and it'll turn into limestone in under two years. It can't solve the whole problem by itself, but there's enough capacity for gigatons of CO2. There are several entities working on this. Here's a company with a small pilot project, and links to scientific papers: https://www.carbfix.com/ https://www.carbfix.com/
  - throwaway316943 6y ago
    I believe basalt can be produced artificially as well, is there a chance we could build limestone farms? That would be a neat trick.
    - corty 6y ago
      Artificial production alone doesn't do the trick. It would have to be low in energy consumption, preferably exothermic. I don't think there is such a reaction with plentifully available material. Otherwise you spend more energy on the basalt than the CO_2 production gave you. Also, large parts of this planet consist of natural basalt deposits, every area with some current or historic vulcanism has them. E.g. half of Siberia is a huge basalt deposit. Google Siberian Trap. So I do not think artificial production would be necessary.
macspoofing 6y ago
>I feel like CO2 sequestration is second only to nuclear in the amount of unfounded concerns The problem with CO2 capture specifically (specifically from the atmosphere as opposed to at the source) is that CO2 comprises a very small part of air. This means you have to move huge amounts of air through a capture device to capture a very small amount of carbon. How is that ever going to make sense?
- elgfare 6y ago
  I guess the low hanging fruit is to attach this to a power plant or some other CO2 emitting process.
  - Jouvence 6y ago
    That's true, but then it is surely better to cut out the middle-man and just not use fossil fuels for static generation in the first place. The energy needs which are hard to meet with renewables (aviation, other large-scale transport) are the same places where CCS is non-viable due to the efficiency hit. The best we can do is decarbonise as quickly as possible, and live with the fallout of our failure to act this far - unless a significant use for captured CO2 is identified, atmospheric capture technology will always struggle with commercial viability.
    - GekkePrutser 6y ago
      > unless a significant use for captured CO2 is identified And a significant use that does not end in it being released to the atmosphere after being used :)
    - elgfare 6y ago
      The best we can do is to do everything we can. It might also be interesting to start burning biomass and capturing the CO2, which would be net negative. Maybe it's viable for cement production as well.
- quotemstr 6y ago
  It makes sense because brute force engineering solutions are frequently the right ones. If you capture carbon from the air, you can mass produce one kind of capture facility and spam as many copies of this facility as you need (at low cost, thanks to mass production) to give humanity closed-loop control over atmospheric composition. If you rely on source emissions control only, you need finnicky source-specific installation and control technology everywhere, which greatly increases the cost and complexity of the implementation. And there are places where you can't realistically do carbon capture and sequestration, e.g. jet engines. On top of all that, we live in a world with multiple governments and jurisdictions, and not all of them agree on the right level of investment in source capture. Do you really expect developing countries to give up on coal generation right away? What are you going to do, bomb them into the stone age? A climate management solution must be robust against the problem of uncooperative actors. We can't rely on everyone getting along and singing carbon kumbaya. Compared to source mitigations, an atmospheric capture approach is simpler, more robust, and better capable of dealing with uncooperative emitters. Yes, you have to move a lot of air, but that's just energy, and energy is cheap if you're not picky about geography or uptime, and it's especially cheap if you're not squeamish about nuclear.
magicalhippo 6y ago
> I also happen to think a $100 per tonne carbon price is not such a bad idea. Government here in Norway recently released their climate plan, and part of it was the gradual increase to 2000 NOK (~234 USD) per tonne of CO2 in 2030[1]. Not sure if it survives the years of politics between then and now though... [1]: https://www.dn.no/politikk/erna-solberg/sveinung-rotevatn/klima/klimaplan-varsler-kraftig-okning-av-co2-avgiften-til-2000-kroner/2-1-941319 https://www.dn.no/politikk/erna-solberg/sveinung-rotevatn/kl...
- layoutIfNeeded 6y ago
  Does this include the carbon ultimately released from oil that was sold to other countries by Norway?
  - extropy 6y ago
    I would guess no. The buyer could be pumping it back in the ground for all the seller knows. Requirement to sell "carbon neutral" oil to countries that do not have their own carbon capture rules would be an interesting idea. Could as well add another tax for all the other nasty chemicals the refinement process releases.
    - layoutIfNeeded 6y ago
      >The buyer could be pumping it back in the ground for all the seller knows. Yeah, I’m afraid I don’t buy this reasoning...
  - deleted 6y ago
    [deleted]
  - magicalhippo 6y ago
    As I understand it no, it only covers usage of oil and other fossil products. On the one hand I absolutely agree that's ignoring a major CO2 source. On the other hand, if Norway added the CO2 tax to exported fossil fuel but other countries did not, would that affect fossil fuel consumption in any meaningful way?
LatteLazy 6y ago
To put it in perspective, 100usd/tn would let me (limey brit) maintain my wasteful lifestyle for just 5300 a year. That's very affordable when the alternatives are Water World level flooding or living like a vegan hermit in a cave...
- quotemstr 6y ago
  > 100usd/tn would let me (limey brit) maintain my wasteful lifestyle for just 5300 a year. That's very affordable In the eyes of the annoying kind of climate activist, the affordability you've mentioned is a bug, not a feature. Too many people who claim to care about the planet want to use the climate as a pretext to reform everyone's lifestyle and to roll back industrial civilization more generally. This sort of activist doesn't see the carbon problem as an engineering challenge, but instead as a political and aesthetic project. It's super annoying, because people like this reject technology that would let us have our modern lifestyle cake and eat it too. Not all climate activists are like this, but there are enough of these bad faith people around to seriously impair earnest and good faith efforts to solve the actual engineering side of the carbon problem.
  - GekkePrutser 6y ago
    > to use the climate as a pretext to reform everyone's lifestyle and to roll back industrial civilization more generally. Not roll back. But do smarter. It's not just global warming. We're shipping billions of tons of stuff from one side of the planet to another in sulphur-blowing rustbuckets. Creating continents of floating plastic in the oceans. Causing toxic lakes from harvesting rare earth minerals. We can't keep doing this. Maybe we can keep it up so before your lifetime is over, but sooner or later it's going to be a problem that can't be avoided just like climate change is now. There's many quick wins here. Buying locally produced foods instead of stuff flown in from half a world away. Not flying across europe for a 1 hour business meeting. Reducing plastic packaging. And there's good news too. We're continuing the excellent path of energy reduction in electric appliances. They had to keep adding "+"es and now rework the entire energy labels in Europe because "A++++" efficiency became too long. I think COVID already brought us halfway there. We're no longer used to business meetings, the fragility of our supply chains has opened up many eyes, and most office workers now work from home at least part time and do just fine. For the environment this has all been pretty great :)
DennisP 6y ago
For electricity generation, it'll be cheaper to build low-carbon generators. For long-distance jet travel, it's probably cheapest to turn the captured CO2 into fuel. For emissions from concrete, ambient capture and sequestration might be best. The great thing about a price on carbon is that the market would sort all this out.
- deleted 6y ago
  [deleted]
- namibj 6y ago
  The emissions from concrete come from limestone kilns, which are even easier to capture the CO2 from than coal power plants.
  - DennisP 6y ago
    Ah, interesting. Agriculture is a pretty diffuse source though. And ultimately, we need to take CO2 levels back down to 350ppm or so.
    - namibj 6y ago
      Oh, for sure.
Gravityloss 6y ago
$50 per tonne? A coal plant produces about a tonne of CO2 for every MWh produced. Industrial electricity price might be $50 per MWh. So just paying for the carbon capture doubles your electricity price? $100 carbon capture charge would triple it. I can't see how this could be competitive. We have an excellent carbon storage technology, it's called coal. And what's best, it's already there, underground, very safely, proven for millions of years! With no cost! But we're still building new coal plants in many places. In some places, coal plants and steel factories have shut down, but it's often because industry has been offshored to a place that uses coal, or they're replaced with natural gas, only a somewhat better alternative. So if leaving coal unused can't be made to work, then more inefficient and thus expensive methods of carbon avoidance likely can't either. It's like working hard in the car wash for the whole day and then at the end of the day, spending all the money you just earned on having your car washed. It's a bad strategy - you would have spent a lot less time and effort if you had just washed your car yourself. When the coal and natural gas plants have been shut down, then carbon capture might have a role. Nice page about world coal usage: https://www.iea.org/reports/coal-information-overview https://www.iea.org/reports/coal-information-overview
- 7952 6y ago
  Co2 pricing is not the only way though. You could give co2 capturing gas peakers a strike price in the same way as renewables. Or have a capacity market that is only open to carbon capturing energy sources.
- tjoff 6y ago
  Double the price of coal sounds like an excellent thing! Still very cheap. Promotes better sources of energy.
  - javajosh 6y ago
    Indeed. The fact is that coal energy externalities have been ignored, artificially depressing the cost. Increasing the cost of a product to reflect those externalities is not a "blow to the industry", but rather the first time in history coal's price will reflect its externalities. Nope, it's not a great time to be a coal-miner, but I hear Biden is trying to spend $4T on infrastructure so maybe some of those miners can buy a truck and form a road maintenance company instead!
linknoid 6y ago
Maybe you can help enlighten me on this. I've been struggling to understand the basics thermodynamics of carbon capture for quite some time. So we have a hydro-carbon, we mix it with oxygen, and the oxygen combines with the hydrogen and the carbon, and releases heat as a byproduct. The heat energy increases the pressure of the newly created CO2. This higher pressure is placed on one side of a turbine or a piston, and we extract useful work by moving it from a high density state to a low density state, causing it to cool in the process. Now it seems like if you want to re-concentrate that CO2, it should take at least as much work to compress it back to its original size as it released when you burned it in the first place, and probably a lot more, because the CO2 has been diffused into the general atmosphere. To state it more succinctly, we extract work through a pressure differential, and by reversing that pressure differential, won't that require more work than we got out in the first place by the second law of thermodynamics? I ignored the part where part of the energy is coming from the hydrogen. Is the hydrogen -> water where most of the energy is coming from, and the carbon part relatively insignificant?
- ethagknight 6y ago
  The goal is not to re-create fuel, but to clean up the waste. This is more like sweeping out the ashtray
- khuey 6y ago
  Enthalpy of combustion for CH4 is 802 kJ and for an equivalent amount of gaseous hydrogen it's 286 kJ so most of the energy does come from the carbon.
  - jjk166 6y ago
    That's not how chemistry works. Burning 1 CH4 is not the same as burning 1 C and 2 H2. The formation of carbon dioxide (aka the combustion of carbon) contributes 393.5 kJ per mole of CH4 combusted, and the formation of water (aka the combustion of hydrogen) contributes 483.6 kJ per mole of CH4, the activation energy to split the CH4 molecule is 74.8 kJ per mole of CH4 combusted. So 55% of the heat released per mole is from the hydrogen.
- 6y ago
marcosdumay 6y ago
> My experience on a 2009 carbon capture plant design was that approx $100 per tonne of CO2 was the lowest carbon price that would really make carbon sequestration highly attractive and widespread. Is there a market for captured carbon? I understand there is a small market for industrial process and carbonated water, but are there people buying long-term capture in large enough quantities to make an impact? Anyway, I don't think the price matters on that scale. Once we decarbonize electricity, I think it will be governments and non-profits that will do most of the carbon capture (unless there exists a large market for my previous question), and for those a lower price only means a higher rate of growth, not the difference between viable or non-viable.
tgsovlerkhgsel 6y ago
The fossil fuel CO2 tax in Switzerland is currently 96 CHF = 102 USD.

GekkePrutser 6y ago

Ok closed loop sounds better, the article didn't clarify this. But the compression itself and the heating will cost significant energy too, don't forget this. But consider for a moment how much coal and oil we've been digging up since the industrial age. CO2 is much less dense once it's uncontained underground. It won't stay liquid at that pressure. In that case we'll need to have underground space of a size of many times the space that all that coal and oil took up, due to the lower density. Just pumping it there, forcing it underground in different spots etc will also cause significant ecological disruption. It's a lot of land we're going to be running pipelines to, drilling into to inject it, using heavy machinery etc. And if some of it does end up being released due to a mistake, it can have potentially deadly effects. Like what happened at Lake Nyos. Safety would really have to be guaranteed. I don't know, it just sounds like a solution that won't scale to the enormity of the climate problems, and rather more like big business wanting to monetise the problem itself (and also use it as an excuse to not reduce consumption). But anyway, if it does prove itself in trials I would change my mind on it.

londons_explore 6y ago
The little detail that injecting CO2 into gas and oil wells can help get more gas and oil out of them is the main reason companies are investing in this tech. If the government can be persuaded to pay for the research, all the better!
- PaulHoule 6y ago
  In Texas you can find big pockets of CO2 undeground and pdople havd been driling holes into those and pumping the CO2 into oil wells. Thus the pipeline, injection, etc. are all developed. CO2 at 1200 psi will mix with oil very well and do wonders getting into pores, but to scale up storage there are not enough oil wells and we'd probably store in saline aquifers.
DennisP 6y ago
One great idea for storage is underground basalt formations. Inject CO2, and it'll turn into limestone in under two years. It can't solve the whole problem by itself, but there's enough capacity for gigatons of CO2. There are several entities working on this. Here's a company with a small pilot project, and links to scientific papers: https://www.carbfix.com/ https://www.carbfix.com/
- throwaway316943 6y ago
  I believe basalt can be produced artificially as well, is there a chance we could build limestone farms? That would be a neat trick.
  - corty 6y ago
    Artificial production alone doesn't do the trick. It would have to be low in energy consumption, preferably exothermic. I don't think there is such a reaction with plentifully available material. Otherwise you spend more energy on the basalt than the CO_2 production gave you. Also, large parts of this planet consist of natural basalt deposits, every area with some current or historic vulcanism has them. E.g. half of Siberia is a huge basalt deposit. Google Siberian Trap. So I do not think artificial production would be necessary.

macspoofing 6y ago

>I feel like CO2 sequestration is second only to nuclear in the amount of unfounded concerns The problem with CO2 capture specifically (specifically from the atmosphere as opposed to at the source) is that CO2 comprises a very small part of air. This means you have to move huge amounts of air through a capture device to capture a very small amount of carbon. How is that ever going to make sense?

elgfare 6y ago
I guess the low hanging fruit is to attach this to a power plant or some other CO2 emitting process.
- Jouvence 6y ago
  That's true, but then it is surely better to cut out the middle-man and just not use fossil fuels for static generation in the first place. The energy needs which are hard to meet with renewables (aviation, other large-scale transport) are the same places where CCS is non-viable due to the efficiency hit. The best we can do is decarbonise as quickly as possible, and live with the fallout of our failure to act this far - unless a significant use for captured CO2 is identified, atmospheric capture technology will always struggle with commercial viability.
  - GekkePrutser 6y ago
    > unless a significant use for captured CO2 is identified And a significant use that does not end in it being released to the atmosphere after being used :)
  - elgfare 6y ago
    The best we can do is to do everything we can. It might also be interesting to start burning biomass and capturing the CO2, which would be net negative. Maybe it's viable for cement production as well.
quotemstr 6y ago
It makes sense because brute force engineering solutions are frequently the right ones. If you capture carbon from the air, you can mass produce one kind of capture facility and spam as many copies of this facility as you need (at low cost, thanks to mass production) to give humanity closed-loop control over atmospheric composition. If you rely on source emissions control only, you need finnicky source-specific installation and control technology everywhere, which greatly increases the cost and complexity of the implementation. And there are places where you can't realistically do carbon capture and sequestration, e.g. jet engines. On top of all that, we live in a world with multiple governments and jurisdictions, and not all of them agree on the right level of investment in source capture. Do you really expect developing countries to give up on coal generation right away? What are you going to do, bomb them into the stone age? A climate management solution must be robust against the problem of uncooperative actors. We can't rely on everyone getting along and singing carbon kumbaya. Compared to source mitigations, an atmospheric capture approach is simpler, more robust, and better capable of dealing with uncooperative emitters. Yes, you have to move a lot of air, but that's just energy, and energy is cheap if you're not picky about geography or uptime, and it's especially cheap if you're not squeamish about nuclear.

magicalhippo 6y ago

> I also happen to think a $100 per tonne carbon price is not such a bad idea. Government here in Norway recently released their climate plan, and part of it was the gradual increase to 2000 NOK (~234 USD) per tonne of CO2 in 2030[1]. Not sure if it survives the years of politics between then and now though... [1]: https://www.dn.no/politikk/erna-solberg/sveinung-rotevatn/klima/klimaplan-varsler-kraftig-okning-av-co2-avgiften-til-2000-kroner/2-1-941319 https://www.dn.no/politikk/erna-solberg/sveinung-rotevatn/kl...

layoutIfNeeded 6y ago
Does this include the carbon ultimately released from oil that was sold to other countries by Norway?
- extropy 6y ago
  I would guess no. The buyer could be pumping it back in the ground for all the seller knows. Requirement to sell "carbon neutral" oil to countries that do not have their own carbon capture rules would be an interesting idea. Could as well add another tax for all the other nasty chemicals the refinement process releases.
  - layoutIfNeeded 6y ago
    >The buyer could be pumping it back in the ground for all the seller knows. Yeah, I’m afraid I don’t buy this reasoning...
- deleted 6y ago
  [deleted]
- magicalhippo 6y ago
  As I understand it no, it only covers usage of oil and other fossil products. On the one hand I absolutely agree that's ignoring a major CO2 source. On the other hand, if Norway added the CO2 tax to exported fossil fuel but other countries did not, would that affect fossil fuel consumption in any meaningful way?

LatteLazy 6y ago

To put it in perspective, 100usd/tn would let me (limey brit) maintain my wasteful lifestyle for just 5300 a year. That's very affordable when the alternatives are Water World level flooding or living like a vegan hermit in a cave...

quotemstr 6y ago
> 100usd/tn would let me (limey brit) maintain my wasteful lifestyle for just 5300 a year. That's very affordable In the eyes of the annoying kind of climate activist, the affordability you've mentioned is a bug, not a feature. Too many people who claim to care about the planet want to use the climate as a pretext to reform everyone's lifestyle and to roll back industrial civilization more generally. This sort of activist doesn't see the carbon problem as an engineering challenge, but instead as a political and aesthetic project. It's super annoying, because people like this reject technology that would let us have our modern lifestyle cake and eat it too. Not all climate activists are like this, but there are enough of these bad faith people around to seriously impair earnest and good faith efforts to solve the actual engineering side of the carbon problem.
- GekkePrutser 6y ago
  > to use the climate as a pretext to reform everyone's lifestyle and to roll back industrial civilization more generally. Not roll back. But do smarter. It's not just global warming. We're shipping billions of tons of stuff from one side of the planet to another in sulphur-blowing rustbuckets. Creating continents of floating plastic in the oceans. Causing toxic lakes from harvesting rare earth minerals. We can't keep doing this. Maybe we can keep it up so before your lifetime is over, but sooner or later it's going to be a problem that can't be avoided just like climate change is now. There's many quick wins here. Buying locally produced foods instead of stuff flown in from half a world away. Not flying across europe for a 1 hour business meeting. Reducing plastic packaging. And there's good news too. We're continuing the excellent path of energy reduction in electric appliances. They had to keep adding "+"es and now rework the entire energy labels in Europe because "A++++" efficiency became too long. I think COVID already brought us halfway there. We're no longer used to business meetings, the fragility of our supply chains has opened up many eyes, and most office workers now work from home at least part time and do just fine. For the environment this has all been pretty great :)

DennisP 6y ago

For electricity generation, it'll be cheaper to build low-carbon generators. For long-distance jet travel, it's probably cheapest to turn the captured CO2 into fuel. For emissions from concrete, ambient capture and sequestration might be best. The great thing about a price on carbon is that the market would sort all this out.

deleted 6y ago
[deleted]
namibj 6y ago
The emissions from concrete come from limestone kilns, which are even easier to capture the CO2 from than coal power plants.
- DennisP 6y ago
  Ah, interesting. Agriculture is a pretty diffuse source though. And ultimately, we need to take CO2 levels back down to 350ppm or so.
  - namibj 6y ago
    Oh, for sure.

Gravityloss 6y ago

$50 per tonne? A coal plant produces about a tonne of CO2 for every MWh produced. Industrial electricity price might be $50 per MWh. So just paying for the carbon capture doubles your electricity price? $100 carbon capture charge would triple it. I can't see how this could be competitive. We have an excellent carbon storage technology, it's called coal. And what's best, it's already there, underground, very safely, proven for millions of years! With no cost! But we're still building new coal plants in many places. In some places, coal plants and steel factories have shut down, but it's often because industry has been offshored to a place that uses coal, or they're replaced with natural gas, only a somewhat better alternative. So if leaving coal unused can't be made to work, then more inefficient and thus expensive methods of carbon avoidance likely can't either. It's like working hard in the car wash for the whole day and then at the end of the day, spending all the money you just earned on having your car washed. It's a bad strategy - you would have spent a lot less time and effort if you had just washed your car yourself. When the coal and natural gas plants have been shut down, then carbon capture might have a role. Nice page about world coal usage: https://www.iea.org/reports/coal-information-overview https://www.iea.org/reports/coal-information-overview

7952 6y ago
Co2 pricing is not the only way though. You could give co2 capturing gas peakers a strike price in the same way as renewables. Or have a capacity market that is only open to carbon capturing energy sources.
tjoff 6y ago
Double the price of coal sounds like an excellent thing! Still very cheap. Promotes better sources of energy.
- javajosh 6y ago
  Indeed. The fact is that coal energy externalities have been ignored, artificially depressing the cost. Increasing the cost of a product to reflect those externalities is not a "blow to the industry", but rather the first time in history coal's price will reflect its externalities. Nope, it's not a great time to be a coal-miner, but I hear Biden is trying to spend $4T on infrastructure so maybe some of those miners can buy a truck and form a road maintenance company instead!

linknoid 6y ago

Maybe you can help enlighten me on this. I've been struggling to understand the basics thermodynamics of carbon capture for quite some time. So we have a hydro-carbon, we mix it with oxygen, and the oxygen combines with the hydrogen and the carbon, and releases heat as a byproduct. The heat energy increases the pressure of the newly created CO2. This higher pressure is placed on one side of a turbine or a piston, and we extract useful work by moving it from a high density state to a low density state, causing it to cool in the process. Now it seems like if you want to re-concentrate that CO2, it should take at least as much work to compress it back to its original size as it released when you burned it in the first place, and probably a lot more, because the CO2 has been diffused into the general atmosphere. To state it more succinctly, we extract work through a pressure differential, and by reversing that pressure differential, won't that require more work than we got out in the first place by the second law of thermodynamics? I ignored the part where part of the energy is coming from the hydrogen. Is the hydrogen -> water where most of the energy is coming from, and the carbon part relatively insignificant?

ethagknight 6y ago
The goal is not to re-create fuel, but to clean up the waste. This is more like sweeping out the ashtray
khuey 6y ago
Enthalpy of combustion for CH4 is 802 kJ and for an equivalent amount of gaseous hydrogen it's 286 kJ so most of the energy does come from the carbon.
- jjk166 6y ago
  That's not how chemistry works. Burning 1 CH4 is not the same as burning 1 C and 2 H2. The formation of carbon dioxide (aka the combustion of carbon) contributes 393.5 kJ per mole of CH4 combusted, and the formation of water (aka the combustion of hydrogen) contributes 483.6 kJ per mole of CH4, the activation energy to split the CH4 molecule is 74.8 kJ per mole of CH4 combusted. So 55% of the heat released per mole is from the hydrogen.
6y ago

marcosdumay 6y ago

> My experience on a 2009 carbon capture plant design was that approx $100 per tonne of CO2 was the lowest carbon price that would really make carbon sequestration highly attractive and widespread. Is there a market for captured carbon? I understand there is a small market for industrial process and carbonated water, but are there people buying long-term capture in large enough quantities to make an impact? Anyway, I don't think the price matters on that scale. Once we decarbonize electricity, I think it will be governments and non-profits that will do most of the carbon capture (unless there exists a large market for my previous question), and for those a lower price only means a higher rate of growth, not the difference between viable or non-viable.

tgsovlerkhgsel 6y ago

The fossil fuel CO2 tax in Switzerland is currently 96 CHF = 102 USD.