13 ms·

So let's do some math. Let's consider natural gas. According to the US government [1], natural gas produced 1.358x10^12 kWh of power and 5.6x10^8 metric tons of

by cletus 5y ago

So let's do some math. Let's consider natural gas. According to the US government [1], natural gas produced 1.358x10^12 kWh of power and 5.6x10^8 metric tons of CO2 so 1 metric ton of CO2 equates to ~2400 kWh of produced power. This post suggests the energy cost is ~230kWh/ton. This is an important sanity check because it means that (capital costs aside) and if it scales you could technically remain carbon neutral for a net output of energy. While this is of course only in a lab and they mention "battery" one should remain skeptical (since pretty much every battery "breakthrough" is nothing more than marketing for research funding). This may be in the paper but in this summary I didn't see anything about how the CO2 needs to be delivered. Does it need to be in a relatively pure form? What sort of preprocessing is required? As for the capital costs, it's hard to say anything concrete here other than if silver and Gallium are catalysts, they're both relatively cheap at that scale (Gallium seems to be <$250/kg according to some quick Googling). Catalysts tend to have a lifespan so those aren't one-time costs generally but still. It's also not clear how much of each material is required. Not to be a broken record on HN, but I've often said--and I'll repeat here--that I don't believe altruism will solve greenhouse gas emissions and global warming: it'll only be solved when it becomes economic to do so. Another way of putting that is when the cost of carbon capture and/or non-greenhouse gas emitting energy sources is profitable, that's when you'll see change. [1]: https://www.eia.gov/tools/faqs/faq.php?id=74&t=11 https://www.eia.gov/tools/faqs/faq.php?id=74&t=11

sabujp 5y ago
does the semiconductor industry not use large quantities of GaAs? Has the industry replaced its use with something else? https://en.wikipedia.org/wiki/Gallium_arsenide https://en.wikipedia.org/wiki/Gallium_arsenide
rbanffy 5y ago
> Another way of putting that is when the cost of carbon capture and/or non-greenhouse gas emitting energy sources is profitable, that's when you'll see change. We may be underpricing the collapse of our civilization due to climate change. It'll be extremely inconvenient and really bad for businesses all over.
punnerud 5y ago
The cost of 230kWh is around €30 in Norway (lower during the summer), the CO2 quota price is around €60/ton. Norway is now building pipes to pump CO2 down to the old oil wells. Seems like it starting to get economically profitable to grab CO2 from the air and sell the quota?
- londons_explore 5y ago
  > Norway is now building pipes to pump CO2 down to the old oil wells. You should know that injecting old oil wells with CO2 helps them produce more oil. The CO2 becomes carbonic acid under pressure, which then dissolves pores in the rock wider, allowing more oil and gas to escape. Also, it looks pretty doubtful that CO2 will stay in gas wells for a long time. Eventually it'll find some fissure and due to the acidity any crack will be eroded wider till all the CO2 comes out like a fizzy drink. But don't worry. Oil and gas companies will happily collect government subsidies for pumping CO2 underground to get more oil out to sell, in the knowledge that when the gas escapes in a few decades they can act all surprised...
  - ericd 5y ago
    Yeah, it’s been branded “enhanced oil recovery”, and iirc it’s currently the most economically rewarding use for CO2.
  - HPsquared 5y ago
    That's interesting, I'd always thought it was more the CO2 acting as a solvent to flush out the oil. Is there any reading material on this?
    - punnerud 5y ago
      https://www.equinor.com/en/magazine/carbon-capture-and-storage.html https://www.equinor.com/en/magazine/carbon-capture-and-stora...
- lrem 5y ago
  Note that €30 is obtained with pure CO2 as input. What's the cost of going from air to that? Or even from exhaust to that?
andi999 5y ago
So reducing petrol demand (let's say by switching to electric cars) might reduce the economic incentives of carbon capture significantly, interesting thought.
- cogman10 5y ago
  The economics of a natural carbon market will never work out. There is simply too much carbon available for too low of a price. The carbon capture market NEEDS to have public funding/intervention to make it profitable. Now, carbon capture will be important if we want to have a chance of undoing atmospheric CO2, but IMO, while now it the time to invest in research it's not the time to deploy. More public/government funds need to be pushed towards limiting CO2 output and eliminating sources of CO2. The notion of carbon capture is much the same as having urine capture in a swimming pool. There is no way it won't cost more energy to remove than it produced when released.
  - seventhtiger 5y ago
    Urine capture would work great if it's attached to every person. Even with renewable energy and electric transportation, if we could keep using oil but not produce CO2, then we should. Cheap energy is lifting humanity out of poverty.
    - adrianN 5y ago
      You're assuming that the carbon capture process is cheaper than the shrinking price advantage of fossil fuels over renewables.
      - seventhtiger 5y ago
        I'm not. I'm just leaving room for an equilibrium that includes oil. I don't believe we'll be able to take cheap sources of power offline without affecting the bottom line for the developing world. Poor countries can't make the choice to regulate themselves into worse conditions. Centralizing carbon capture at power plants can be cost effective. The tech is almost within reach. It will vastly increase the amount of available energy in the world.
adrian_b 5y ago
"how the CO2 needs to be delivered": The experiments described in the paper have used pure CO2. The conversion process is unlikely to work directly with air, because it decomposes CO2 into solid carbon partially oxidated and dioxygen. If one of the products of the catalyzed reaction, i.e. oxygen from the air, would be present in a much larger concentration than the input substance (CO2), like in the air, the conversion reaction will either stop completely or it will be at least slowed down a lot. So besides the costs for the energy and for renewing the silver and gallium from time to time and also for the organic solvents that might also need to be replaced from time to time, the cost of separating CO2 from the air must be added. Nevertheless, it might still eventually be cheaper than alternative methods, as most of them also need to first separate the CO2 from the air. In any case, much more research is needed to scale this from experiments in minute quantities to industrial dimensions.
- cletus 5y ago
  A big issue with renewable energy, particularly solar and wind, is that the power output is variable and an electric grid needs a base load to operate. Now I firmly believe the future here is ultimately space-based solar power collectors. I've seen estimates that a panel in space around Earth can generate ~7 times the power it can on Earth. This is a deep topic but generating power in space for use on Earth isn't as crazy as it may sound. Anyway, another potential application is to use variable power output for useful purposes on-site. For example, you can extract CO2 directly from the atmosphere and with simply chemistry you can make gasoline from that. This is currently cost-prohibitive so no one does it. At some point this may become economic, in which case the variable power output won't be an issue. You're now only interested in the total output. You also don't lose power from transmission or require the capital cost of transmission lines. Perhaps CO2 capture is another potential such application. Either the CO2 could be processed on site with a process like this and the byproducts (pure carbon and oxygen) can be sold.
  - laserbeam 5y ago
    > space-based solar power Cute, but very much off topic. Lets have that discussion on an article about energy generation, not about carbon capture.
dr_dshiv 5y ago
>I'll repeat here--that I don't believe altruism will solve greenhouse gas emissions and global warming: it'll only be solved when it becomes economic to do so. Completely agree. We need governments to ensure externalities (both positive and negative) are reflected in market pricing so that economic forces can operate efficiently. Implication: there must be a debt to pay for past and present GHG output. It should not be punitive. But it should be clear and predictable.
- hcurtiss 5y ago
  Who would pay that debt for past emissions, and what price should they pay?
  - smitty1e 5y ago
    I'm not sure, but there is little more terrifying short of a nuclear accident than the idea of faceless people in an office somewhere deciding who gets a pass and who gets crushed for sins uncommitted by them. In short: you hint at tryanny.
  - c1sc0 5y ago
    Boomers. Everything they own.
    - deleted 5y ago
      [deleted]
  - rtpg 5y ago
    Perhaps society as a whole should just try to solve these problems. This is the tarpit of market-based solutions: debating endlessly about who bears costs, instead of just doing collective things collectively. And if you do have markets, every middleman and their dog will demand their slice of the pie.
    - voakbasda 5y ago
      The only way to get everyone to participate in a solution will be regulation. The last thing that I want is the government regulating this market. We will end up with another cartel like the oil industry.
johnchristopher 5y ago
Do we need something like... Business, corporations can't do one thing: not making money. If they don't and can't pay taxes they go bankrupt and can't operate anymore. Can we have a carbon bankrupt ? If a company can't prove they are not emitting CO2 or getting CO2 out of the atmosphere then they are not allowed to operate anymore ? I know it's nickelodeonsimplistic but can't carbon emissions be considered more important than money when deciding to allow companies to operate ?
api 5y ago
To those who think it sounds impossible, remember that methane is CH4 and a good amount of the energy released is attributable to those hydrogens getting together with oxygen. So you are basically subtracting the yield from carbon. Wouldn’t it be a lot better though to somehow turn CH4 into hydrogen and carbon, bury the carbon or use it for uses that don’t end up in the atmosphere, and burn the hydrogen alone or use it in fuel cells? Fuel cells might get you to pretty good energy yields.
credit_guy 5y ago
> This is an important sanity check You have a bug somewhere, I'm not sure where. Roughly speaking the heat of combustion is proportional to the number of atoms of oxygen in the molecules coming out of the reaction. So CH4 + 2 O2 = CO2 + 2 H20 If you hypothetically split CH4 first, you get CH4 + 2 O2 = (C + 2 H2) + 2 O2 = (C + O2) + (2 H2 + O2) = CO2 + 2H20 The first reaction is endothermic, but it absorbs much less heat than the heat produced by the second part of the reaction. So, you can roughly say that the energy coming from burning CH4 comes half from burning the Carbon and half from burning the Hydrogen. Now, if you can make the reverse reaction CO2 -> C + O2 with 100% efficiency, then sure, you get to economically burn CH4 with zero emissions. But if that reaction has only 50% efficiency, then all your (energetic) profit has been wiped out. The article doesn't say what efficiency this envisioned reaction has, but I'd be mightily surprised if it were 50%. Much better to not burn the Carbon to begin with. That is what methane pyrolysis [1] tries to do. [1] https://en.wikipedia.org/wiki/Pyrolysis#Methane_pyrolysis_for_hydrogen https://en.wikipedia.org/wiki/Pyrolysis#Methane_pyrolysis_fo...
- nkingsy 5y ago
  The article clearly states a claimed 92% efficiency.
  - credit_guy 5y ago
    Good point. But there are two problems with that claim. One is about an order a magnitude, the other about a sign. The first one: if you burn 1kg of pure Carbon, you get 3.67 kg of CO2 and 32.8 MegaJoules [1], which is the same as 32800 kJ or, 32800/3600 kWh. That's 9.11 kWh for each 3.67 kg of CO2, or 2.4848 kWh/kg. That's quite close to 2500 kWh/ton. They are claiming it takes them 230 kWh/ton to reverse this reaction. You can see this is an order of magnitude wrong. Let's say they meant to say 2300 kWh/ton. If you divide that by 2500 kWh/ton you get exactly 92% that they claim. But here's the second mistake: you need to put more, not less energy to split CO2, otherwise you'd get energy for free. 2300 kWh/ton is simply impossible. You need to use more than that, and actually more than 2500 kWh/ton if you don't want to violate the first principle of thermodynamics. [1] https://en.wikipedia.org/wiki/Heat_of_combustion#Heat_of_combustion_tables https://en.wikipedia.org/wiki/Heat_of_combustion#Heat_of_com...
fredgrott 5y ago
They stated it operates at room temp so I am assuming that one could in fact pipe in CO2 from factory stacks once some processing of cooling the CO2 from the factory stacks has been implemented. Give you an idea. Gen plant burning natural gas produces CO2, use some of gen electric to cool the emitted CO2 down then mine the result battery artifacts
xyzzy21 5y ago
This also assumes pure CO2 input. That's perhaps possible if you are collecting CO2 fresh off an engine or similar process. However if you are talking about CO2 already in the air, you have a MASSIVE amount of energy required to separate/concentrate the CO2 FIRST.
- photochemsyn 5y ago
  There's major catalyst poisoning issues with trying to capture coal/oil/gas combustion streams, which can be contaminated with everything from nitrogen oxides and polcyclic aromatic hydrocarbons, to sulfur and arsenic and mercury. Even though you have to expend energy to preconcentrate CO2, the benefit of having a clean stream (assuming not downwind of Los Angeles) of CO2 is that further industrial chemistry is much easier, catalysts last much longer, etc.
theropost 5y ago
Also keep in mind the limited supply/uses of Gallium at the moment, it tends to be a biproduct from other mining activities. If suddenly there were a large and scaled demand for this material, then I am quite sure we would see a huge spike in price in the near/medium term, and future price would depend on the new demand, and capabilities to get sufficient supply. $250/kg is pretty cheap at the moment;
ineedasername 5y ago
don't believe altruism will solve greenhouse gas emissions and global warming: it'll only be solved when it becomes economic to do so. You've listed altruism and economics, but may have discounted self-interest-- not financial, but survival. Young adults especially are both at an age where they can expect to feel some especially nasty impacts of climate change, and at a point in their career where they can begin making decisions accordingly. The generations above that have family, children, etc, and that too is at least a mix of self interest and , I supposed, a form of altruism directed towards your family. It's not easy for us to think in such timelines and abstract outcomes, but we're making progress in that direction. I'm not saying self-interest in terms of self preservation will be the key factor here either, just that it not just about a sort of mechanical economic optimization point. At some tipping point, economic w/ technological advances will converge with self preservation. I guess the question is whether or not that will happen soon enough to really matter. Economics may be the dominant factor now, but the worse things get, the less that economics will matter in making decisions, the more that self preservation will become dominant.
- jvanderbot 5y ago
  I think environmental issues are the classic tragedy of the commons. The first to put aside environmental issues in favor of riches will have a disproportionate advantage with a proportionate impact. One country burning gas gets cheap fuel to expand their industries but only has a marginal increase in future global warming and (the worst part) almost no impact on today's temperature. We need more than altruism, which is local sacrifice. We need global enforcement and agreement and, I agree with GP, incentive.
- BurningFrog 5y ago
  Global climate change is not something one person or family can affect, so I don't understand what form of self-interest driven action could impact it. BTW, the "economic" solution consists of making it in everyone's self interest to work against CO₂ emissions.
hexane360 5y ago
The news reporting on this article has been a little misleading. First, the main goal of this is not to reduce CO2 into carbon, but simply to sequester CO2. The "carbonaceous sheets" that are produced are "graphene oxide", which is less oxidized than CO2 but still highly oxygenated. So the energy required is much less than what would be needed to reduce CO2 completely. But yeah, you won't be able to burn the end product.
- mah4k4l 5y ago
  Ok makes a hell of a lot more sense now. Thanks for pointing that out.
jandrewrogers 5y ago
Gallium cannot be produced at scale because it does not form concentrated ores in nature. It cannot be usefully mined directly. The only reason it is relatively inexpensive is that there is limited demand for the minuscule quantities that are currently produced. Gallium is currently supplied by reprocessing the waste from other convenient metal ores to extract the traces of gallium. Even if we maximized gallium extraction from these waste streams, we are talking about a few thousand tons of gallium per year. We produce more gold every year than there is practically available gallium. Unfortunately this is the story with many proposed solutions to carbon capture. Many things are possible as a prototype which are completely infeasible at the industrial scales required to make a dent in atmospheric carbon because the resources don't exist to run chemistry at that scale.
- evgen 5y ago
  > The only reason [Gallium] is relatively inexpensive is that there is limited demand for the minuscule quantities that are currently produced. It is possible that we might be able to find more if we actively start looking for it? This would not be the first time that what was once a waste product becomes valuable once we know how to use it. Regarding gallium itself, its presence as basically waste product in bauxite ore suggests we can increase production (https://www.sciencedirect.com/science/article/abs/pii/S0301420715001233 https://www.sciencedirect.com/science/article/abs/pii/S03014...) and there may be other sources if we start searching.
  - jandrewrogers 5y ago
    Gallium is found everywhere, it doesn't make sense to actively search for it because it doesn't concentrate anywhere. That's the whole problem. There is little that distinguishes bauxite ore from my backyard in terms of the amount of gallium that can be extracted. The advantage of extracting it from certain ore waste streams is two-fold even though they don't contain much gallium. First, the chemical processing cost varies with the chemistry of the rocks you extract the gallium from, and certain types of ore waste such as bauxite, zinc, etc are cheaper to deal with. Second, these rocks have already been dug out of the ground as part of a mining operation, which is much cheaper than strip mining an arbitrary place to extract the same trace quantities of gallium -- you get to free-ride on the extraction costs of the primary mineral someone already paid for. If it doesn't matter where you dig, then all you can really optimize for is the processing cost of where someone already dug. It would make no sense to increase bauxite production for the purpose of gallium production. Extracting gallium from bauxite is only economical to the extent that there is healthy demand for the aluminum produced from that bauxite. This is common in mining operations -- a secondary mineral that cannot be economically mined by itself becomes profitably extractable from the same ore if and only if the primary mineral is sufficiently profitable. Many less common metals are produced solely via secondary extraction because they cannot be profitably mined directly even when they concentrate.
5faulker 5y ago
It's the same story of business and innovation as usual. And what about the pollution raw materials can cause....
joe_the_user 5y ago
Not to be a broken record on HN, but I've often said--and I'll repeat here--that I don't believe altruism will solve greenhouse gas emissions and global warming: it'll only be solved when it becomes economic to do so. The term "economic" can mean a lot of things. Solar and Wind can be cost-effect replacements for many uses of fossil fuel. With some regulations and transformation of daily surplus energy to other forms, you could get an economy with energy costs similar to the present and low carbon usage. So if "economic" just means, idk, works in an economy, then it's essentially not an important barrier (except the state should finance it's efforts with a graduated income tax and not a visibly-punishing measures like carbon or at-the-pump taxes, instead just making some things eventually prohibited but cushioning the blow for those poor or industries want to preserve). But if by "economic", you mean the economy has to just do what it "wants" with no intervention at all, well we'll not only suffer the disasters of global warming but also unbridled pollution.
lisper 5y ago
> it'll only be solved when it becomes economic to do so. That's true, but the economics are being badly skewed by not properly accounting for the externalities of emissions. If this were done (e.g. a global carbon tax) the situation would change dramatically. If you are a young person reading this I would seriously consider making this a litmus test for any politician you are considering voting for, and urging your peers to do the same. Otherwise your generation is in for a (literally!) a world of hurt.
amelius 5y ago
How much energy does it cost to simply heat CO2 to the point where it breaks into its constituents?
deleted 5y ago
[deleted]
jeffybefffy519 5y ago
Preprint of the paper is available in other parts of this post, but it does say this: > The solid co-contributor of silver-gallium rods ensures a cyclic sustainable process Unsure if this means the gallium is consumed or not during the process.

by cletus 5y ago

sabujp 5y ago

does the semiconductor industry not use large quantities of GaAs? Has the industry replaced its use with something else? https://en.wikipedia.org/wiki/Gallium_arsenide https://en.wikipedia.org/wiki/Gallium_arsenide

rbanffy 5y ago

> Another way of putting that is when the cost of carbon capture and/or non-greenhouse gas emitting energy sources is profitable, that's when you'll see change. We may be underpricing the collapse of our civilization due to climate change. It'll be extremely inconvenient and really bad for businesses all over.

punnerud 5y ago

The cost of 230kWh is around €30 in Norway (lower during the summer), the CO2 quota price is around €60/ton. Norway is now building pipes to pump CO2 down to the old oil wells. Seems like it starting to get economically profitable to grab CO2 from the air and sell the quota?

londons_explore 5y ago
> Norway is now building pipes to pump CO2 down to the old oil wells. You should know that injecting old oil wells with CO2 helps them produce more oil. The CO2 becomes carbonic acid under pressure, which then dissolves pores in the rock wider, allowing more oil and gas to escape. Also, it looks pretty doubtful that CO2 will stay in gas wells for a long time. Eventually it'll find some fissure and due to the acidity any crack will be eroded wider till all the CO2 comes out like a fizzy drink. But don't worry. Oil and gas companies will happily collect government subsidies for pumping CO2 underground to get more oil out to sell, in the knowledge that when the gas escapes in a few decades they can act all surprised...
- ericd 5y ago
  Yeah, it’s been branded “enhanced oil recovery”, and iirc it’s currently the most economically rewarding use for CO2.
- HPsquared 5y ago
  That's interesting, I'd always thought it was more the CO2 acting as a solvent to flush out the oil. Is there any reading material on this?
  - punnerud 5y ago
    https://www.equinor.com/en/magazine/carbon-capture-and-storage.html https://www.equinor.com/en/magazine/carbon-capture-and-stora...
lrem 5y ago
Note that €30 is obtained with pure CO2 as input. What's the cost of going from air to that? Or even from exhaust to that?

andi999 5y ago

So reducing petrol demand (let's say by switching to electric cars) might reduce the economic incentives of carbon capture significantly, interesting thought.

cogman10 5y ago
The economics of a natural carbon market will never work out. There is simply too much carbon available for too low of a price. The carbon capture market NEEDS to have public funding/intervention to make it profitable. Now, carbon capture will be important if we want to have a chance of undoing atmospheric CO2, but IMO, while now it the time to invest in research it's not the time to deploy. More public/government funds need to be pushed towards limiting CO2 output and eliminating sources of CO2. The notion of carbon capture is much the same as having urine capture in a swimming pool. There is no way it won't cost more energy to remove than it produced when released.
- seventhtiger 5y ago
  Urine capture would work great if it's attached to every person. Even with renewable energy and electric transportation, if we could keep using oil but not produce CO2, then we should. Cheap energy is lifting humanity out of poverty.
  - adrianN 5y ago
    You're assuming that the carbon capture process is cheaper than the shrinking price advantage of fossil fuels over renewables.
    - seventhtiger 5y ago
      I'm not. I'm just leaving room for an equilibrium that includes oil. I don't believe we'll be able to take cheap sources of power offline without affecting the bottom line for the developing world. Poor countries can't make the choice to regulate themselves into worse conditions. Centralizing carbon capture at power plants can be cost effective. The tech is almost within reach. It will vastly increase the amount of available energy in the world.

adrian_b 5y ago

"how the CO2 needs to be delivered": The experiments described in the paper have used pure CO2. The conversion process is unlikely to work directly with air, because it decomposes CO2 into solid carbon partially oxidated and dioxygen. If one of the products of the catalyzed reaction, i.e. oxygen from the air, would be present in a much larger concentration than the input substance (CO2), like in the air, the conversion reaction will either stop completely or it will be at least slowed down a lot. So besides the costs for the energy and for renewing the silver and gallium from time to time and also for the organic solvents that might also need to be replaced from time to time, the cost of separating CO2 from the air must be added. Nevertheless, it might still eventually be cheaper than alternative methods, as most of them also need to first separate the CO2 from the air. In any case, much more research is needed to scale this from experiments in minute quantities to industrial dimensions.

cletus 5y ago
A big issue with renewable energy, particularly solar and wind, is that the power output is variable and an electric grid needs a base load to operate. Now I firmly believe the future here is ultimately space-based solar power collectors. I've seen estimates that a panel in space around Earth can generate ~7 times the power it can on Earth. This is a deep topic but generating power in space for use on Earth isn't as crazy as it may sound. Anyway, another potential application is to use variable power output for useful purposes on-site. For example, you can extract CO2 directly from the atmosphere and with simply chemistry you can make gasoline from that. This is currently cost-prohibitive so no one does it. At some point this may become economic, in which case the variable power output won't be an issue. You're now only interested in the total output. You also don't lose power from transmission or require the capital cost of transmission lines. Perhaps CO2 capture is another potential such application. Either the CO2 could be processed on site with a process like this and the byproducts (pure carbon and oxygen) can be sold.
- laserbeam 5y ago
  > space-based solar power Cute, but very much off topic. Lets have that discussion on an article about energy generation, not about carbon capture.

dr_dshiv 5y ago

>I'll repeat here--that I don't believe altruism will solve greenhouse gas emissions and global warming: it'll only be solved when it becomes economic to do so. Completely agree. We need governments to ensure externalities (both positive and negative) are reflected in market pricing so that economic forces can operate efficiently. Implication: there must be a debt to pay for past and present GHG output. It should not be punitive. But it should be clear and predictable.

hcurtiss 5y ago
Who would pay that debt for past emissions, and what price should they pay?
- smitty1e 5y ago
  I'm not sure, but there is little more terrifying short of a nuclear accident than the idea of faceless people in an office somewhere deciding who gets a pass and who gets crushed for sins uncommitted by them. In short: you hint at tryanny.
- c1sc0 5y ago
  Boomers. Everything they own.
  - deleted 5y ago
    [deleted]
- rtpg 5y ago
  Perhaps society as a whole should just try to solve these problems. This is the tarpit of market-based solutions: debating endlessly about who bears costs, instead of just doing collective things collectively. And if you do have markets, every middleman and their dog will demand their slice of the pie.
  - voakbasda 5y ago
    The only way to get everyone to participate in a solution will be regulation. The last thing that I want is the government regulating this market. We will end up with another cartel like the oil industry.

johnchristopher 5y ago

Do we need something like... Business, corporations can't do one thing: not making money. If they don't and can't pay taxes they go bankrupt and can't operate anymore. Can we have a carbon bankrupt ? If a company can't prove they are not emitting CO2 or getting CO2 out of the atmosphere then they are not allowed to operate anymore ? I know it's nickelodeonsimplistic but can't carbon emissions be considered more important than money when deciding to allow companies to operate ?

api 5y ago

To those who think it sounds impossible, remember that methane is CH4 and a good amount of the energy released is attributable to those hydrogens getting together with oxygen. So you are basically subtracting the yield from carbon. Wouldn’t it be a lot better though to somehow turn CH4 into hydrogen and carbon, bury the carbon or use it for uses that don’t end up in the atmosphere, and burn the hydrogen alone or use it in fuel cells? Fuel cells might get you to pretty good energy yields.

credit_guy 5y ago

> This is an important sanity check You have a bug somewhere, I'm not sure where. Roughly speaking the heat of combustion is proportional to the number of atoms of oxygen in the molecules coming out of the reaction. So CH4 + 2 O2 = CO2 + 2 H20 If you hypothetically split CH4 first, you get CH4 + 2 O2 = (C + 2 H2) + 2 O2 = (C + O2) + (2 H2 + O2) = CO2 + 2H20 The first reaction is endothermic, but it absorbs much less heat than the heat produced by the second part of the reaction. So, you can roughly say that the energy coming from burning CH4 comes half from burning the Carbon and half from burning the Hydrogen. Now, if you can make the reverse reaction CO2 -> C + O2 with 100% efficiency, then sure, you get to economically burn CH4 with zero emissions. But if that reaction has only 50% efficiency, then all your (energetic) profit has been wiped out. The article doesn't say what efficiency this envisioned reaction has, but I'd be mightily surprised if it were 50%. Much better to not burn the Carbon to begin with. That is what methane pyrolysis [1] tries to do. [1] https://en.wikipedia.org/wiki/Pyrolysis#Methane_pyrolysis_for_hydrogen https://en.wikipedia.org/wiki/Pyrolysis#Methane_pyrolysis_fo...

nkingsy 5y ago
The article clearly states a claimed 92% efficiency.
- credit_guy 5y ago
  Good point. But there are two problems with that claim. One is about an order a magnitude, the other about a sign. The first one: if you burn 1kg of pure Carbon, you get 3.67 kg of CO2 and 32.8 MegaJoules [1], which is the same as 32800 kJ or, 32800/3600 kWh. That's 9.11 kWh for each 3.67 kg of CO2, or 2.4848 kWh/kg. That's quite close to 2500 kWh/ton. They are claiming it takes them 230 kWh/ton to reverse this reaction. You can see this is an order of magnitude wrong. Let's say they meant to say 2300 kWh/ton. If you divide that by 2500 kWh/ton you get exactly 92% that they claim. But here's the second mistake: you need to put more, not less energy to split CO2, otherwise you'd get energy for free. 2300 kWh/ton is simply impossible. You need to use more than that, and actually more than 2500 kWh/ton if you don't want to violate the first principle of thermodynamics. [1] https://en.wikipedia.org/wiki/Heat_of_combustion#Heat_of_combustion_tables https://en.wikipedia.org/wiki/Heat_of_combustion#Heat_of_com...

fredgrott 5y ago

They stated it operates at room temp so I am assuming that one could in fact pipe in CO2 from factory stacks once some processing of cooling the CO2 from the factory stacks has been implemented. Give you an idea. Gen plant burning natural gas produces CO2, use some of gen electric to cool the emitted CO2 down then mine the result battery artifacts

xyzzy21 5y ago

This also assumes pure CO2 input. That's perhaps possible if you are collecting CO2 fresh off an engine or similar process. However if you are talking about CO2 already in the air, you have a MASSIVE amount of energy required to separate/concentrate the CO2 FIRST.

photochemsyn 5y ago
There's major catalyst poisoning issues with trying to capture coal/oil/gas combustion streams, which can be contaminated with everything from nitrogen oxides and polcyclic aromatic hydrocarbons, to sulfur and arsenic and mercury. Even though you have to expend energy to preconcentrate CO2, the benefit of having a clean stream (assuming not downwind of Los Angeles) of CO2 is that further industrial chemistry is much easier, catalysts last much longer, etc.

theropost 5y ago

Also keep in mind the limited supply/uses of Gallium at the moment, it tends to be a biproduct from other mining activities. If suddenly there were a large and scaled demand for this material, then I am quite sure we would see a huge spike in price in the near/medium term, and future price would depend on the new demand, and capabilities to get sufficient supply. $250/kg is pretty cheap at the moment;

ineedasername 5y ago

don't believe altruism will solve greenhouse gas emissions and global warming: it'll only be solved when it becomes economic to do so. You've listed altruism and economics, but may have discounted self-interest-- not financial, but survival. Young adults especially are both at an age where they can expect to feel some especially nasty impacts of climate change, and at a point in their career where they can begin making decisions accordingly. The generations above that have family, children, etc, and that too is at least a mix of self interest and , I supposed, a form of altruism directed towards your family. It's not easy for us to think in such timelines and abstract outcomes, but we're making progress in that direction. I'm not saying self-interest in terms of self preservation will be the key factor here either, just that it not just about a sort of mechanical economic optimization point. At some tipping point, economic w/ technological advances will converge with self preservation. I guess the question is whether or not that will happen soon enough to really matter. Economics may be the dominant factor now, but the worse things get, the less that economics will matter in making decisions, the more that self preservation will become dominant.

jvanderbot 5y ago
I think environmental issues are the classic tragedy of the commons. The first to put aside environmental issues in favor of riches will have a disproportionate advantage with a proportionate impact. One country burning gas gets cheap fuel to expand their industries but only has a marginal increase in future global warming and (the worst part) almost no impact on today's temperature. We need more than altruism, which is local sacrifice. We need global enforcement and agreement and, I agree with GP, incentive.
BurningFrog 5y ago
Global climate change is not something one person or family can affect, so I don't understand what form of self-interest driven action could impact it. BTW, the "economic" solution consists of making it in everyone's self interest to work against CO₂ emissions.

hexane360 5y ago

The news reporting on this article has been a little misleading. First, the main goal of this is not to reduce CO2 into carbon, but simply to sequester CO2. The "carbonaceous sheets" that are produced are "graphene oxide", which is less oxidized than CO2 but still highly oxygenated. So the energy required is much less than what would be needed to reduce CO2 completely. But yeah, you won't be able to burn the end product.

mah4k4l 5y ago
Ok makes a hell of a lot more sense now. Thanks for pointing that out.

jandrewrogers 5y ago

Gallium cannot be produced at scale because it does not form concentrated ores in nature. It cannot be usefully mined directly. The only reason it is relatively inexpensive is that there is limited demand for the minuscule quantities that are currently produced. Gallium is currently supplied by reprocessing the waste from other convenient metal ores to extract the traces of gallium. Even if we maximized gallium extraction from these waste streams, we are talking about a few thousand tons of gallium per year. We produce more gold every year than there is practically available gallium. Unfortunately this is the story with many proposed solutions to carbon capture. Many things are possible as a prototype which are completely infeasible at the industrial scales required to make a dent in atmospheric carbon because the resources don't exist to run chemistry at that scale.

evgen 5y ago
> The only reason [Gallium] is relatively inexpensive is that there is limited demand for the minuscule quantities that are currently produced. It is possible that we might be able to find more if we actively start looking for it? This would not be the first time that what was once a waste product becomes valuable once we know how to use it. Regarding gallium itself, its presence as basically waste product in bauxite ore suggests we can increase production (https://www.sciencedirect.com/science/article/abs/pii/S0301420715001233 https://www.sciencedirect.com/science/article/abs/pii/S03014...) and there may be other sources if we start searching.
- jandrewrogers 5y ago
  Gallium is found everywhere, it doesn't make sense to actively search for it because it doesn't concentrate anywhere. That's the whole problem. There is little that distinguishes bauxite ore from my backyard in terms of the amount of gallium that can be extracted. The advantage of extracting it from certain ore waste streams is two-fold even though they don't contain much gallium. First, the chemical processing cost varies with the chemistry of the rocks you extract the gallium from, and certain types of ore waste such as bauxite, zinc, etc are cheaper to deal with. Second, these rocks have already been dug out of the ground as part of a mining operation, which is much cheaper than strip mining an arbitrary place to extract the same trace quantities of gallium -- you get to free-ride on the extraction costs of the primary mineral someone already paid for. If it doesn't matter where you dig, then all you can really optimize for is the processing cost of where someone already dug. It would make no sense to increase bauxite production for the purpose of gallium production. Extracting gallium from bauxite is only economical to the extent that there is healthy demand for the aluminum produced from that bauxite. This is common in mining operations -- a secondary mineral that cannot be economically mined by itself becomes profitably extractable from the same ore if and only if the primary mineral is sufficiently profitable. Many less common metals are produced solely via secondary extraction because they cannot be profitably mined directly even when they concentrate.

5faulker 5y ago

It's the same story of business and innovation as usual. And what about the pollution raw materials can cause....

joe_the_user 5y ago

Not to be a broken record on HN, but I've often said--and I'll repeat here--that I don't believe altruism will solve greenhouse gas emissions and global warming: it'll only be solved when it becomes economic to do so. The term "economic" can mean a lot of things. Solar and Wind can be cost-effect replacements for many uses of fossil fuel. With some regulations and transformation of daily surplus energy to other forms, you could get an economy with energy costs similar to the present and low carbon usage. So if "economic" just means, idk, works in an economy, then it's essentially not an important barrier (except the state should finance it's efforts with a graduated income tax and not a visibly-punishing measures like carbon or at-the-pump taxes, instead just making some things eventually prohibited but cushioning the blow for those poor or industries want to preserve). But if by "economic", you mean the economy has to just do what it "wants" with no intervention at all, well we'll not only suffer the disasters of global warming but also unbridled pollution.

lisper 5y ago

> it'll only be solved when it becomes economic to do so. That's true, but the economics are being badly skewed by not properly accounting for the externalities of emissions. If this were done (e.g. a global carbon tax) the situation would change dramatically. If you are a young person reading this I would seriously consider making this a litmus test for any politician you are considering voting for, and urging your peers to do the same. Otherwise your generation is in for a (literally!) a world of hurt.

amelius 5y ago

How much energy does it cost to simply heat CO2 to the point where it breaks into its constituents?

deleted 5y ago

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jeffybefffy519 5y ago

Preprint of the paper is available in other parts of this post, but it does say this: > The solid co-contributor of silver-gallium rods ensures a cyclic sustainable process Unsure if this means the gallium is consumed or not during the process.