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Getting C out of CO2 require more energy than burning C to get CO2, otherwise you'd get perpetual motion. So, if you want to reduce CO2 emissions, you're better

Getting C out of CO2 require more energy than burning C to get CO2, otherwise you'd get perpetual motion. So, if you want to reduce CO2 emissions, you're better off not burning the C to begin with rather than trying to split the CO2 after the C was burnt.

jsharf 5y ago
Are there any chemical carbon configurations more stable than CO2 which are solid?
- philipkglass 5y ago
  Yes, carbonates of alkaline earth metals (e.g. magnesium and calcium) are solids at STP and more stable than carbon dioxide. See section 7.2.2 "Chemistry of mineral carbonation" in this IPCC report: https://www.ipcc.ch/site/assets/uploads/2018/03/srccs_chapter7-1.pdf https://www.ipcc.ch/site/assets/uploads/2018/03/srccs_chapte... Even at the low partial pressure of atmospheric CO2 and at ambient temperature, carbonation of metal oxide bearing minerals occurs spontaneously, though on geological time scales (Robie et al., 1978; Lasaga and Berner, 1998). Limitations arise from the formation of silica or carbonate layers on the mineral surface during carbonation that tend to hinder further reaction and to limit conversion (Butt et al., 1996) and from the rate of CO2 uptake from the gas phase in the case of aqueous reactions. The challenge for mineral carbonation is to find ways to accelerate carbonation and to exploit the heat of reaction within the environmental constraints, for example with minimal energy and material losses.
not2b 5y ago
Agreed, the only way this can be useful is to do both: stop burning carbon; use processes like this to recover the carbon from processes where there isn't a good alternative to producing CO2 output. Cement production, perhaps.
- midjji 5y ago
  There are a number of marine processes which permanently bind carbon, and they do increase with increased CO2 concentration. Problem is that they are overwhelmed by current production. If we reduce CO2 production to zero, the earth will mostly bounce back on its own in a century or two.
lovecg 5y ago
Even if we stop all emissions right now, the CO2 already in the air will stay there for a while. We need some way to recapture it if we want to return to pre-industrial levels.
- anonporridge 5y ago
  And that might take centuries to do, so we'll probably end up doing some kind of geo-engineering to interrupt the buildup of heat to give us time to extract the carbon.
  - lovecg 5y ago
    Or, pessimistically, we’ll do the geo-engineering step without ever reigning in the new emissions and call it done.
    - anonporridge 5y ago
      That outcome isn't necessarily bad. It's somewhat arrogant of us to assume that we understand enough about a system as complex as the Earth's biosphere and atmosphere to know for sure a larger percentage of CO2 will necessarily be bad long term. It's feasible that it could be better, even if only after a painful transition. I for one find the future where we're not actively managing the Earth's climate in some way to be the more pessimistic outcome. It indicates that civilization has failed to continue advancing, probably isn't spacefaring, and that the light of consciousness will eventually twinkle out once the Earth becomes uninhabitable in about 500 million years. We'll see.
      - AnthonyMouse 5y ago
        > It's somewhat arrogant of us to assume that we understand enough about a system as complex as the Earth's biosphere and atmosphere to know for sure a larger percentage of CO2 will necessarily be bad long term. It's feasible that it could be better, even if only after a painful transition. That's the problem. Maybe it's better, maybe it's worse, and there is only one way to find out. But if it's worse, finding out is very bad. And there is no way to know ahead of time.
renewiltord 5y ago
He's not talking about perpetual motion. The input energy into this hypothetical spherical-cow process is concentrated reflected insolation. Unfortunately, getting the Ga2O back to being liquid Ga is probably the problem.
- analog31 5y ago
  How is it smelted from ore in the first place? Quick look suggests that it starts out as an oxide, and is a byproduct of aluminum production.
- Iwan-Zotow 5y ago
  > getting the Ga2O back to being liquid Ga is probably the problem guess, the same way we got it - bath, electricity, cathode and anode
SilasX 5y ago
No. That doesn't follow at all, and I wish people would stop repeating this overclever "proof". Burning fossil fuels for energy: hydrocarbon + O2 -> atmospheric CO2 + other stuff Sequestration: atmospheric CO2 -> not-amospheric-CO2 e.g. solid C + other stuff Notice that those are not exact reverses of each other, so there is no requirement that the energy released in one be the same quantity as the energy absorbed in the other. Hydrocarbon fuels have very high Gibbs free energy. Solid carbon does not. We're only trying to get the CO2 out of the atmosphere, not return it to the form of the original fuel that was burned. Therefore, sequestration can potentially require less energy than was originally released from burning the hydrocarbons.
- marcosdumay 5y ago
  It's not a general rule for all capture processes, but on the case of solid carbon you do need to put back most of the energy yo get by burning the fuel. Solid carbon is basically coal. It has more usable energy per mass than any hydrocarbon, and just a little bit less per carbon.
  - random314 5y ago
    > you do need to put back most of the energy yo get by burning the fuel. And we can get this energy from sunlight.
    - marcosdumay 5y ago
      Well, we can. But it would make no sense to deploy something like this before our electricity generation is decarbonized. Other capture processes do not share that issue. But nobody is planning on deploying something like it currently anyway.
- infogulch 5y ago
  Combustion is an energetic oxidation. The primary chemical energy change is combining the oxygen with other stuff to produce stuff-oxide. If you want the stuff back out in its pure form you absolutely do have to put in more energy in to remove the oxygen than the combustion result produced. Now, depending on the chemical reaction, sometimes the "more energy in" is "waaay more energy in", which can certainly be improved with catalysts and the like, but that can only create improvements like 100x to 1.1x, which is great!, but always >1.
Pxtl 5y ago
There are some industrial processes like blast furnaces where it's hard to come up with a better heat source than fire. That might be a place where this tech could help.
- MertsA 5y ago
  I think a better example might be cement production. For a blast furnace you don't just need heat, you need to chemically react some reducing agent with the iron ore. Generally that's either coal coke or methane reacting with the iron oxide to produce iron and carbon dioxide. There's technologies on the horizon that could enable electrolytic refining of iron much like how aluminum is refined. With cement production there's no potential method to eliminate the carbon dioxide. You still have the extreme heat of the process so natural gas and coal are a pretty good fit but even if you sidestepped that and heated it through other means, you're ultimately taking calcium carbonate and calcining it to calcium oxide. Even if you eliminated all coal usage you'd at best cut the amount of CO2 released by half. With a good carbon capture system connected to cement kilns you could actually use concrete to capture CO2 from the air. Concrete naturally forms calcium carbonate over time as it ages so you could use it to have concrete production effectively be a net negative for atmospheric CO2. Concrete production currently accounts for 8% of CO2 emissions globally and direct atmospheric capture has been something that's historically difficult due to the low concentration of CO2 in the atmosphere so you could kill two birds with one stone.
  - _nalply 5y ago
    > With cement production there's no potential method to eliminate the carbon dioxide. Please have a look at Limestone Calcined Clay Cement: https://lc3.ch/ https://lc3.ch/ This is only one of the cement alternatives I believe.
  - Pxtl 5y ago
    Either way, point stands: there are industrial processes that are very carbon-intensive in ways that are difficult to replace with electrical power. Carbon-capture in the exhaust system sounds like an excellent solution for these.
neltnerb 5y ago
Yeah, I was about to say... as great as this seems like it may be, surely turning CO2 into coal isn't a net gain versus not burning the coal. But there are plenty of point emitters of CO2, so if we imagine a grid that's actually renewable sure. Capture though? It could always be paired with another capture method to concentrate it first, it's usually cheap to concentrate things a little and expensive to concentrate them a lot.
spartanatreyu 5y ago
Even if capturing uses more energy than emitting, it can still be useful since we can Maxwell's Demon the whole process. We can decide only to emit CO2 at the times when we don't have clean energy ready to use and decide to recapture CO2 when we do have clean energy to use.
- nikanj 5y ago
  Unfortunately we have collectively decided that solving hashes is a better use for clean energy
  - pawelmurias 5y ago
    Maybe we could start minting coins or NFTs from captured CO2?
    - aperson_hello 5y ago
      This would be an interesting approach! Not sure how it would work in practice, but it's a fun thought... And there could be inherent value there, especially as a carbon capture tax credit. Instead of proof of work or proof of state, it's proof of capture. You'd have to put together some kind of distributed capture hardware, but... That's maybe possible with current tech?
      - nikanj 5y ago
        Unfortunately the fact that it has a clearly measurable value means it's price is pegged to that value. If this token gets you $100 worth of carbon emissions, it's hard to justify a price higher than $100. If the token gets you absolutely nothing, then the value is absolutely arbitrary - enabling spectacular rise
        aperson_hello 5y ago
        What if you tied it to a desktop carbon capture device (understood that these don't really exist currently)? Doesn't even have to be particularly efficient, nor tied to carbon credits.
ajuc 5y ago
Yes, recapturing CO2 at the powerplant is pointless because of conservation of energy. It's always better not to burn the carbon in the first place. But recapturing CO2 from air isn't pointless - because we can use surplus renewable energy to do so (and then burn C later as fuel). Basically it would use air as infinite capacity (but low-efficiency) rechargeable battery. I've seen estimates of about 13% efficiency over the whole cycle (capturing + burning).
- AnthonyMouse 5y ago
  Is there any known or predicted capture technology that does this more efficiently than by growing plants or algae and then burying them underground and/or using them as biofuels?
  - ajuc 5y ago
    According to this guy [1] in less than a decade it will be cheaper to produce hydrocarbons out of air and water + surplus renewable energy than by pumping them out of ground. Which is in turn cheaper than biofuels. [1] https://caseyhandmer.wordpress.com/2021/11/01/scaling-carbon-capture/ https://caseyhandmer.wordpress.com/2021/11/01/scaling-carbon...
  - nwiswell 5y ago
    Yes. CO2 can be frozen out of the air as snow at sufficiently low temperatures. This could be done at scale in central Antarctica using enormous refrigerating complexes[1], but it would be the most ambitious engineering project ever undertaken by humanity. Generally this is not seriously discussed by experts as a solution to global warming not because it is not feasible, but because it would diminish the sense of urgency and discourage the much more prudent and affordable approach of simply reducing emissions. [1] https://journals.ametsoc.org/view/journals/apme/52/2/jamc-d-12-0110.1.xml https://journals.ametsoc.org/view/journals/apme/52/2/jamc-d-...
    - DemocracyFTW 5y ago
      > Generally this is not seriously discussed by experts as a solution to global warming not because it is not feasible, but because it would diminish the sense of urgency Let us say it is not being discussed because it is not feasible. Unless of course we build massive nuclear power plants in Antarctica with all what that entails. We are not any time soon in a position where we can produce any nontrivial amount of solar or wind energy in the hostile environment of that continent, plus it's dark night down there for half a year each year. Meaning the only remaining option would be to ship coal or oil down there to burn it so we can cool air to –140°C, obviously a non-starter if there ever was one. > and discourage the much more prudent and affordable approach of simply reducing emissions. This. The entire plan is madness: you'd burn two tons of oil and coal to get rid of part of what burning one ton of oil and coal leave behind in the atmosphere. It is not clear to me at this point if it is at all feasible to use fossil fuel to get more CO2 out of the atmosphere than burning it puts into the atmosphere in the first place. Because in this household we obey the laws of thermodynamic. And if it's possible at all it's not easy to see why continuing to burn oil and coal and capturing the CO2 at other sites should be better than not burning part of those fuels and capturing the CO2 right at their point of emission should be the better option. It is a hare-brained plan.
rocqua 5y ago
We don't burn pure C to make CO2 though. We burn hydrocarbons. I am not sure what the effects of the longer carbon chain is. But I feel certain the other extra parts of hydrocarbons leave more energy on the table. The output might be quite low. But I doubt it would be negative.
- throwaway81523 5y ago
  Coal is pure carbon more or less. You are right that the math is a bit different for gas and oil.
DennisP 5y ago
That's a good reason not to apply this technology to smokestacks, since that would make a power plant into a power consumer. However, in some cases it's quite difficult to stop burning C. Long-haul jets are one example. So for those, it makes sense to make carbon-neutral liquid fuels, even though there's an energy penalty. Pull CO2 from the atmosphere, use renewables or nuclear as an energy source to turn it into fuel. CO2 emissions from steel plants might be another good application. Ideally we might be better off using clean energy sources to displace fossil plants, but that doesn't happen as fast as we'd like for all sorts of political and economic reasons. So we might as well get started now on other reductions, because it'll still help some, and we can get it scaled up by the time we've decarbonized the energy grid and want to decarbonize everything else.
midjji 5y ago
Luckily there are these rocks which get hot just lying around, more so if you concentrate them, and we have millions of years of current power consumption of those to use. Perfectly CO2 free too.
- ahpeeyem 5y ago
  Unless you're Australia, where we shut down our geothermal trials after some early success. Ignore those rocks that are already hot, let's keep digging up these black ones and burning them!

jsharf 5y ago

Are there any chemical carbon configurations more stable than CO2 which are solid?

philipkglass 5y ago
Yes, carbonates of alkaline earth metals (e.g. magnesium and calcium) are solids at STP and more stable than carbon dioxide. See section 7.2.2 "Chemistry of mineral carbonation" in this IPCC report: https://www.ipcc.ch/site/assets/uploads/2018/03/srccs_chapter7-1.pdf https://www.ipcc.ch/site/assets/uploads/2018/03/srccs_chapte... Even at the low partial pressure of atmospheric CO2 and at ambient temperature, carbonation of metal oxide bearing minerals occurs spontaneously, though on geological time scales (Robie et al., 1978; Lasaga and Berner, 1998). Limitations arise from the formation of silica or carbonate layers on the mineral surface during carbonation that tend to hinder further reaction and to limit conversion (Butt et al., 1996) and from the rate of CO2 uptake from the gas phase in the case of aqueous reactions. The challenge for mineral carbonation is to find ways to accelerate carbonation and to exploit the heat of reaction within the environmental constraints, for example with minimal energy and material losses.

not2b 5y ago

Agreed, the only way this can be useful is to do both: stop burning carbon; use processes like this to recover the carbon from processes where there isn't a good alternative to producing CO2 output. Cement production, perhaps.

midjji 5y ago
There are a number of marine processes which permanently bind carbon, and they do increase with increased CO2 concentration. Problem is that they are overwhelmed by current production. If we reduce CO2 production to zero, the earth will mostly bounce back on its own in a century or two.

lovecg 5y ago

Even if we stop all emissions right now, the CO2 already in the air will stay there for a while. We need some way to recapture it if we want to return to pre-industrial levels.

anonporridge 5y ago
And that might take centuries to do, so we'll probably end up doing some kind of geo-engineering to interrupt the buildup of heat to give us time to extract the carbon.
- lovecg 5y ago
  Or, pessimistically, we’ll do the geo-engineering step without ever reigning in the new emissions and call it done.
  - anonporridge 5y ago
    That outcome isn't necessarily bad. It's somewhat arrogant of us to assume that we understand enough about a system as complex as the Earth's biosphere and atmosphere to know for sure a larger percentage of CO2 will necessarily be bad long term. It's feasible that it could be better, even if only after a painful transition. I for one find the future where we're not actively managing the Earth's climate in some way to be the more pessimistic outcome. It indicates that civilization has failed to continue advancing, probably isn't spacefaring, and that the light of consciousness will eventually twinkle out once the Earth becomes uninhabitable in about 500 million years. We'll see.
    - AnthonyMouse 5y ago
      > It's somewhat arrogant of us to assume that we understand enough about a system as complex as the Earth's biosphere and atmosphere to know for sure a larger percentage of CO2 will necessarily be bad long term. It's feasible that it could be better, even if only after a painful transition. That's the problem. Maybe it's better, maybe it's worse, and there is only one way to find out. But if it's worse, finding out is very bad. And there is no way to know ahead of time.

renewiltord 5y ago

He's not talking about perpetual motion. The input energy into this hypothetical spherical-cow process is concentrated reflected insolation. Unfortunately, getting the Ga2O back to being liquid Ga is probably the problem.

analog31 5y ago
How is it smelted from ore in the first place? Quick look suggests that it starts out as an oxide, and is a byproduct of aluminum production.
Iwan-Zotow 5y ago
> getting the Ga2O back to being liquid Ga is probably the problem guess, the same way we got it - bath, electricity, cathode and anode

SilasX 5y ago

No. That doesn't follow at all, and I wish people would stop repeating this overclever "proof". Burning fossil fuels for energy: hydrocarbon + O2 -> atmospheric CO2 + other stuff Sequestration: atmospheric CO2 -> not-amospheric-CO2 e.g. solid C + other stuff Notice that those are not exact reverses of each other, so there is no requirement that the energy released in one be the same quantity as the energy absorbed in the other. Hydrocarbon fuels have very high Gibbs free energy. Solid carbon does not. We're only trying to get the CO2 out of the atmosphere, not return it to the form of the original fuel that was burned. Therefore, sequestration can potentially require less energy than was originally released from burning the hydrocarbons.

marcosdumay 5y ago
It's not a general rule for all capture processes, but on the case of solid carbon you do need to put back most of the energy yo get by burning the fuel. Solid carbon is basically coal. It has more usable energy per mass than any hydrocarbon, and just a little bit less per carbon.
- random314 5y ago
  > you do need to put back most of the energy yo get by burning the fuel. And we can get this energy from sunlight.
  - marcosdumay 5y ago
    Well, we can. But it would make no sense to deploy something like this before our electricity generation is decarbonized. Other capture processes do not share that issue. But nobody is planning on deploying something like it currently anyway.
infogulch 5y ago
Combustion is an energetic oxidation. The primary chemical energy change is combining the oxygen with other stuff to produce stuff-oxide. If you want the stuff back out in its pure form you absolutely do have to put in more energy in to remove the oxygen than the combustion result produced. Now, depending on the chemical reaction, sometimes the "more energy in" is "waaay more energy in", which can certainly be improved with catalysts and the like, but that can only create improvements like 100x to 1.1x, which is great!, but always >1.

Pxtl 5y ago

There are some industrial processes like blast furnaces where it's hard to come up with a better heat source than fire. That might be a place where this tech could help.

MertsA 5y ago
I think a better example might be cement production. For a blast furnace you don't just need heat, you need to chemically react some reducing agent with the iron ore. Generally that's either coal coke or methane reacting with the iron oxide to produce iron and carbon dioxide. There's technologies on the horizon that could enable electrolytic refining of iron much like how aluminum is refined. With cement production there's no potential method to eliminate the carbon dioxide. You still have the extreme heat of the process so natural gas and coal are a pretty good fit but even if you sidestepped that and heated it through other means, you're ultimately taking calcium carbonate and calcining it to calcium oxide. Even if you eliminated all coal usage you'd at best cut the amount of CO2 released by half. With a good carbon capture system connected to cement kilns you could actually use concrete to capture CO2 from the air. Concrete naturally forms calcium carbonate over time as it ages so you could use it to have concrete production effectively be a net negative for atmospheric CO2. Concrete production currently accounts for 8% of CO2 emissions globally and direct atmospheric capture has been something that's historically difficult due to the low concentration of CO2 in the atmosphere so you could kill two birds with one stone.
- _nalply 5y ago
  > With cement production there's no potential method to eliminate the carbon dioxide. Please have a look at Limestone Calcined Clay Cement: https://lc3.ch/ https://lc3.ch/ This is only one of the cement alternatives I believe.
- Pxtl 5y ago
  Either way, point stands: there are industrial processes that are very carbon-intensive in ways that are difficult to replace with electrical power. Carbon-capture in the exhaust system sounds like an excellent solution for these.

neltnerb 5y ago

Yeah, I was about to say... as great as this seems like it may be, surely turning CO2 into coal isn't a net gain versus not burning the coal. But there are plenty of point emitters of CO2, so if we imagine a grid that's actually renewable sure. Capture though? It could always be paired with another capture method to concentrate it first, it's usually cheap to concentrate things a little and expensive to concentrate them a lot.

spartanatreyu 5y ago

Even if capturing uses more energy than emitting, it can still be useful since we can Maxwell's Demon the whole process. We can decide only to emit CO2 at the times when we don't have clean energy ready to use and decide to recapture CO2 when we do have clean energy to use.

nikanj 5y ago
Unfortunately we have collectively decided that solving hashes is a better use for clean energy
- pawelmurias 5y ago
  Maybe we could start minting coins or NFTs from captured CO2?
  - aperson_hello 5y ago
    This would be an interesting approach! Not sure how it would work in practice, but it's a fun thought... And there could be inherent value there, especially as a carbon capture tax credit. Instead of proof of work or proof of state, it's proof of capture. You'd have to put together some kind of distributed capture hardware, but... That's maybe possible with current tech?
    - nikanj 5y ago
      Unfortunately the fact that it has a clearly measurable value means it's price is pegged to that value. If this token gets you $100 worth of carbon emissions, it's hard to justify a price higher than $100. If the token gets you absolutely nothing, then the value is absolutely arbitrary - enabling spectacular rise
      - aperson_hello 5y ago
        What if you tied it to a desktop carbon capture device (understood that these don't really exist currently)? Doesn't even have to be particularly efficient, nor tied to carbon credits.

ajuc 5y ago

Yes, recapturing CO2 at the powerplant is pointless because of conservation of energy. It's always better not to burn the carbon in the first place. But recapturing CO2 from air isn't pointless - because we can use surplus renewable energy to do so (and then burn C later as fuel). Basically it would use air as infinite capacity (but low-efficiency) rechargeable battery. I've seen estimates of about 13% efficiency over the whole cycle (capturing + burning).

AnthonyMouse 5y ago
Is there any known or predicted capture technology that does this more efficiently than by growing plants or algae and then burying them underground and/or using them as biofuels?
- ajuc 5y ago
  According to this guy [1] in less than a decade it will be cheaper to produce hydrocarbons out of air and water + surplus renewable energy than by pumping them out of ground. Which is in turn cheaper than biofuels. [1] https://caseyhandmer.wordpress.com/2021/11/01/scaling-carbon-capture/ https://caseyhandmer.wordpress.com/2021/11/01/scaling-carbon...
- nwiswell 5y ago
  Yes. CO2 can be frozen out of the air as snow at sufficiently low temperatures. This could be done at scale in central Antarctica using enormous refrigerating complexes[1], but it would be the most ambitious engineering project ever undertaken by humanity. Generally this is not seriously discussed by experts as a solution to global warming not because it is not feasible, but because it would diminish the sense of urgency and discourage the much more prudent and affordable approach of simply reducing emissions. [1] https://journals.ametsoc.org/view/journals/apme/52/2/jamc-d-12-0110.1.xml https://journals.ametsoc.org/view/journals/apme/52/2/jamc-d-...
  - DemocracyFTW 5y ago
    > Generally this is not seriously discussed by experts as a solution to global warming not because it is not feasible, but because it would diminish the sense of urgency Let us say it is not being discussed because it is not feasible. Unless of course we build massive nuclear power plants in Antarctica with all what that entails. We are not any time soon in a position where we can produce any nontrivial amount of solar or wind energy in the hostile environment of that continent, plus it's dark night down there for half a year each year. Meaning the only remaining option would be to ship coal or oil down there to burn it so we can cool air to –140°C, obviously a non-starter if there ever was one. > and discourage the much more prudent and affordable approach of simply reducing emissions. This. The entire plan is madness: you'd burn two tons of oil and coal to get rid of part of what burning one ton of oil and coal leave behind in the atmosphere. It is not clear to me at this point if it is at all feasible to use fossil fuel to get more CO2 out of the atmosphere than burning it puts into the atmosphere in the first place. Because in this household we obey the laws of thermodynamic. And if it's possible at all it's not easy to see why continuing to burn oil and coal and capturing the CO2 at other sites should be better than not burning part of those fuels and capturing the CO2 right at their point of emission should be the better option. It is a hare-brained plan.

rocqua 5y ago

We don't burn pure C to make CO2 though. We burn hydrocarbons. I am not sure what the effects of the longer carbon chain is. But I feel certain the other extra parts of hydrocarbons leave more energy on the table. The output might be quite low. But I doubt it would be negative.

throwaway81523 5y ago
Coal is pure carbon more or less. You are right that the math is a bit different for gas and oil.

DennisP 5y ago

That's a good reason not to apply this technology to smokestacks, since that would make a power plant into a power consumer. However, in some cases it's quite difficult to stop burning C. Long-haul jets are one example. So for those, it makes sense to make carbon-neutral liquid fuels, even though there's an energy penalty. Pull CO2 from the atmosphere, use renewables or nuclear as an energy source to turn it into fuel. CO2 emissions from steel plants might be another good application. Ideally we might be better off using clean energy sources to displace fossil plants, but that doesn't happen as fast as we'd like for all sorts of political and economic reasons. So we might as well get started now on other reductions, because it'll still help some, and we can get it scaled up by the time we've decarbonized the energy grid and want to decarbonize everything else.

midjji 5y ago

Luckily there are these rocks which get hot just lying around, more so if you concentrate them, and we have millions of years of current power consumption of those to use. Perfectly CO2 free too.

ahpeeyem 5y ago
Unless you're Australia, where we shut down our geothermal trials after some early success. Ignore those rocks that are already hot, let's keep digging up these black ones and burning them!