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When considering synthetic chemicals made from solar energy, methane is probably one of the last you should consider. Making any type of chemical energy carrie

by hannob 3y ago

When considering synthetic chemicals made from solar energy, methane is probably one of the last you should consider. Making any type of chemical energy carrier comes with substantial losses, so whenever you can, using electricity directly is better. If you absolutely need a chemical energy carrier, the first one you will look at is hydrogen, because it's the simplest and you avoid all the direct air capture or other CO2 sourcing issue. If H2 does not work due to its low volumetric energy density, the next one to consider is ammonia. It has a higher energy density, but it also has some downsides. It's very toxic, it does not burn very well, and burning it causes nasty side products like NOx and N2O. Then there's methanol. In case you want a hydrocarbon, that's almost always better than methane. It's a liquid, which is a huge advantage in ease of handling. Transporting and storing it is a lot easier compared to any type of gas. Methane has the big disadvantage that it's itself a potent greenhouse gas. (Btw, hydrogen also is an indirect greenhouse gas, although not as strong as methane.) The only thing methane has in its favor is existing infrastructure, but it's a weak argument compared to the other downsides.

msandford 3y ago
Failing to understand the enormous amount of methane infrastructure (natural gas) and the utility of reusing it is also a mistake IMO. There's got to be tens of trillions of dollars in deployed methane infrastructure. To suggest that's a weak argument is baffling. Economics are real.
- kibwen 3y ago
  There was just as much sunk cost into coal infrastructure, but that's not an argument against phasing out coal.
  - oh_sigh 3y ago
    Exactly - it is an argument for continuing to use coal, because we have valuable infrastructure even though we know how bad it is for the environment. Which explains why it is so hard to stop using coal.
    - kibwen 3y ago
      In the US, the share of power being generated by coal has fallen from 50% in 2005 to 20% in 2022. (In absolute terms, which is what really matters in an emissions context, it's fallen from 2T kwh to 0.75.) To phase out existing infrastructure just takes incentives and time (and 18 years isn't even that much time on the scale of infrastructure investments). The same can happen to methane infrastructure, especially since non-fossil alternatives are far more viable than they were when coal began to be phased out.
      - pfdietz 3y ago
        And the US has stopped building new coal fired power plants, so a decay to zero is just a matter of time (although it could and should be accelerated.)
  - NickM 3y ago
    Sure, but if we could reuse the coal infrastructure as part of a transition away from fossil fuels, why wouldn't we consider that? Unlike methane, coal is mostly just used for power generation, and there's relatively little infrastructure associated with transporting it. Natural gas is used for furnaces, stoves, dryers, hot water heaters, etc. and there are millions of miles of pipes and associated infrastructure used to transport it directly to peoples' homes. The complexity and cost for retrofitting hundreds of millions of homes and electrifying all the associated appliances is immense, not to mention all the backlash you get from people who love their gas stoves and grills. If we could just switch to generating renewable methane it would be a huge win in terms of logistical simplicity and would minimize disruption to peoples' day to day lives, which would probably make folks a lot more willing to accept it without putting up a huge fight.
    - kibwen 3y ago
      > The complexity and cost for retrofitting hundreds of millions of homes and electrifying all the associated appliances is immense This is overselling the difficulty. What you're saying is true, but you don't need to rip out functioning appliances. Appliances have a finite service lifetime; once they fail, replace them with electrified appliances. Already here in the year 2023, I wouldn't dream of building a house with a gas stove or gas heating. Induction stoves are just plain better than gas stoves, and heat pumps are cheaper than gas heating once you factor in that the gas-heated house will need a separate AC installation for cooling, whereas the heat-pump house won't. These days, methane doesn't make sense anywhere except at the power generation end, and power generation sources are fungible and can be gradually replaced on their own schedule.
  - BobbyJo 3y ago
    Not really. The reason coal was so popular was because you didn't really need any specialized infrastructure. It is a solid you can just ship using the same trains and trucks you use for TVs and apples. So you're really only giving up the mines and power plants.
    - kibwen 3y ago
      This seems to be arguing that the existence of natural gas pipe infrastructure is somehow a benefit of natural gas, rather than a downside. The pipes are an expense, to say nothing of the fact that even our best-maintained pipes are leaking 2% of their gas directly into the atmosphere per year (the worst are leaking double or triple that). A hunk of coal that falls off a truck doesn't contribute to emissions; a leaky methane pipe does, which can actually make natgas plants overall worse for emissions than coal.
      - BobbyJo 3y ago
        Not at all. In another comment I make a similar statement to yours, I'm just pointing out that the coal:methane comparison doesn't make sense.
      - ZeroGravitas 3y ago
        Coal mining is also a major source of methane emissions: https://www.iea.org/reports/global-methane-tracker-2023/strategies-to-reduce-emissions-from-coal-supply https://www.iea.org/reports/global-methane-tracker-2023/stra...
- BobbyJo 3y ago
  > There's got to be tens of trillions of dollars in deployed methane infrastructure Highly doubt it is worth that much presently, so even if the investment was that large (which I doubt) we certainly aren't looking at walking away from that much presently. The big reason to move away from methane is that gas delivery infrastructure is expensive to maintain, and nearly impossible to keep leak free. Reusing existing infrastructure implies investing in its maintenance, which may be more expensive than building new infrastructure for liquid fuel (which itself already exists).
- hannob 3y ago
  The thing is: Most of that infrastructure is obsolete in any case. These synthetic chemicals will play a role in industry and shipping, probably also in long-duration storage. But they won't be in widespread use like fossil gas today. They're just too inefficient.
foxyv 3y ago
The problem with hydrogen is the storage. Although electrolysis and other methods of generating hydrogen are fairly efficient, the cost to compress it is obscene. Sabatier production of Methane is comparable, however we already have infrastructure to use Methane and storage is a solved problem. Methanol production requires methane as a synthesis gas so it just adds another step. Plant based methanol has all the same problems as ethanol. Until we are running electrified tractors and equipment we will probably be carbon positive when producing methanol. There are a few processes which are using waste from coal and concrete plants, but they are unlikely to scale enough to make Methane unnecessary. Currently the best way to store surplus electricity are batteries and pumped hydro.
- pfdietz 3y ago
  For static applications, hydrogen can be easily stored underground. Energy is used to compress it, but that energy can be recovered by running it through an expander (and if the compression/expansion is done in stages to approximate isothermal compression, the round trip efficiency of this can be high.)
  - foxyv 3y ago
    That's really neat! I've mostly seen explanations about Hydrogen as a vehicle fuel so I've never stumbled on cavern storage. It makes sense to use isothermal compression. Especially if you can recover the energy from decompressing the hydrogen using a turbo expander which would be obscenely difficult on a vehicle.
    - _hypx 3y ago
      Why would it be difficult in a car? It is the same principle as a compressed air car: https://en.wikipedia.org/wiki/Compressed-air_car https://en.wikipedia.org/wiki/Compressed-air_car
      - foxyv 3y ago
        A turboexpander in a car would add an obscene amount of cost to an already expensive fuel cell vehicle. Also, it would be a fire and explosion hazard requiring a ton of maintenance.
narag 3y ago
Making any type of chemical energy carrier comes with substantial losses The goal presented in the article seems to be cleaning the atmosphere, not generating chemicals. So H2 and ammonia would be irrelevant. And it's not so much about maximazing efficiency as not losing too much. The alternative should be other carbon-based chemicals, as useful as methane, needed in huge volumes and with a practical process of extraction using solar panels. Is there something like that? Also, is there another product with the same characteristics with methane as a starting point?
- slashdev 3y ago
  That’s nonsensical, because you burn the methane and put the carbon right back into the atmosphere. It didn’t clean anything. It’s merely a carbon neutral form of chemical energy. H2, ammonia, methanol would be just as carbon neutral.
  - narag 3y ago
    Well, it's there in the title of the article, so don't shoot me. If the premise of the article is bs, it doesn't make sense to discuss efficiency. Is it nonsensical though? IDK, it seems somehow better than extracting the gas from the ground and adding it to the system. Also if there's another more complex chemical not for burning, that you can synthesize from the methane, it would be a net gain.
    - slashdev 3y ago
      It’s much better than extracting it from the ground, hence carbon neutral. It is not carbon negative though. The article was reasonably well written, but I can see how you’d draw that conclusion if you only read the title.
NickM 3y ago
the first one you will look at is hydrogen, because it's the simplest Simplest chemically != simplest to use in practice. There are already millions of miles of natural gas pipelines leading directly to peoples' homes, and those pipelines cannot be used with hydrogen (not to mention all the appliances they feed). Renewable methane is a dead simple drop-in replacement for natural gas. None of the other alternatives you mentioned share that property, and I think you're seriously under-weighting the importance of it.
- hannob 3y ago
  None of these chemicals will be used in people's homes in any meaningful quantity. That's just not going to happen due to the conersion inefficiencies.
  - pfdietz 3y ago
    Right. The more efficient way to use methane to heat a home (vs. current furnaces) is to burn it in a CC power plant and heat the home with a heat pump.
    - NickM 3y ago
      Yes, that would be more efficient, but there are so many edge cases where switching an existing home to use heat pumps is prohibitively difficult or expensive. Maybe you have radiators that require higher temps than can be efficiently produced by heat pumps. Maybe you live in a place where the air gets too cold for air source heat pumps to be cost effective. Maybe you want to install ground source, but you live in a city and don't have a big enough yard. Maybe you have a big enough yard but local geological conditions aren't conducive to digging deep enough. Not to mention all the people who just don't want to bother switching, or who don't have the money to switch, or prefer the reliability of the natural gas over the electrical grid, or...etc. Or just look at the culture wars that are already starting over gas stoves, when nobody has even been required to get rid of their existing gas stove, and people are just talking about changing the rules for new construction. There are just so many edge cases where it's hard to get people to switch off natural gas. If we can make green methane, all those problems are simultaneously solved with zero disruption to anyone's homes/lifestyles/etc.
perlgeek 3y ago
Once thing that's missing (from both the article here, and for example the whole hydrogen discussion in Germany) is the round-trip efficiency. Now the author of the article would likely argue that with prices dropping as fast as they do, a 60% efficiency is just a few years delay away from being economically efficient. (A quick search came up with a 68% efficiency for fuel cells and "80% - 95%" for electrolysis, putting the whole thing at 54%-65%) But I can't help but think we'll come up with something a bit more efficient, because that'll be more viable sooner, and more profitable in the long run.
- pfdietz 3y ago
  The relevant applications for hydrogen are ones where efficiency doesn't much matter (long term storage, rare event grid backup). What matters is minimizing capital cost, which probably means using combustion turbines, not fuel cells.
AlanSE 3y ago
I've been following Terraform Industries for a while, and it does strike me as obvious that H2 will be the preferred form of energy storage medium in the long run, not just an intermediate species. Depending on the conditions, if you're doing day-night energy storage, then you would like to fill up the H2 tank and then burn it when demand ramps up. The only role I see for methane is when your H2 tank is already filled up but your solar panels are still producing. This is not just possible, but deterministically required whenever solar gets deployed enough for seasonal storage to be necessary. Right now California is something like 35% solar + wind energy, and the "duck curve" is nearly maxing out. This was predicted in extreme specificity 20 years ago, as >30% and you get stuff like zeroed-out energy prices during the day. We have not solved the day-night (daily) energy storage problem, which only requires storing energy for a matter of hours. When you go to something like 60% renewables, then even crazier stuff happens. Overproduction during sunny times goes bananas and (assuming daily storage is solved, which it isn't) seasonal issues start to arise. I don't think H2 will ever work for seasonal storage, although I think it's fine for multi-day storage scenarios. It's not theoretically impossible, I just compare to the equivalent that we have for natural gas and realize you would need MANY TIMES that level of investment to save the same amount of energy in H2. Plus, fossil fuel gas producers are mostly at a constant level, whereas solar production outright needs summer-to-winter storage. What I don't buy is that these units will be disconnected from the grid and be economical by their gas products. No way, no how. What you want is to run the chemicals plant with low-voltage solar power locally, and trade-off with the grid as is economical.
- rasz 3y ago
  >Right now California is something like 35% solar + wind energy, and the "duck curve" is nearly maxing out. This was predicted in extreme specificity 20 years ago Legislated. Its easy to predict something if you write it into law resulting in shutdown of Nuclear power station (Diablo Canyon) >The main driver deterring PG&E from seeking a 20-year operating licence extension is the 2015 renewable portfolio standard (RPS) of producing 50% of its electricity from qualified renewable energy sources by 2030. PG&E’s model for the future cost of operating Diablo Canyon indicated that the cost per kilowatt hour was going to almost double, since the company would be forced to lower the amount of power it could produce from the plant in order to meet the state’s requirement. Dropping the capacity factor from the current 92% to say 50% would virtually double the price per kilowatt hour since costs are largely fixed. >The state law which effectively dictates that by 2030 Diablo Canyon should operate at lower capacity each year and buy in power from intermittent renewables has apparently sealed the fate of the plant.

by hannob 3y ago

msandford 3y ago

Failing to understand the enormous amount of methane infrastructure (natural gas) and the utility of reusing it is also a mistake IMO. There's got to be tens of trillions of dollars in deployed methane infrastructure. To suggest that's a weak argument is baffling. Economics are real.

kibwen 3y ago
There was just as much sunk cost into coal infrastructure, but that's not an argument against phasing out coal.
- oh_sigh 3y ago
  Exactly - it is an argument for continuing to use coal, because we have valuable infrastructure even though we know how bad it is for the environment. Which explains why it is so hard to stop using coal.
  - kibwen 3y ago
    In the US, the share of power being generated by coal has fallen from 50% in 2005 to 20% in 2022. (In absolute terms, which is what really matters in an emissions context, it's fallen from 2T kwh to 0.75.) To phase out existing infrastructure just takes incentives and time (and 18 years isn't even that much time on the scale of infrastructure investments). The same can happen to methane infrastructure, especially since non-fossil alternatives are far more viable than they were when coal began to be phased out.
    - pfdietz 3y ago
      And the US has stopped building new coal fired power plants, so a decay to zero is just a matter of time (although it could and should be accelerated.)
- NickM 3y ago
  Sure, but if we could reuse the coal infrastructure as part of a transition away from fossil fuels, why wouldn't we consider that? Unlike methane, coal is mostly just used for power generation, and there's relatively little infrastructure associated with transporting it. Natural gas is used for furnaces, stoves, dryers, hot water heaters, etc. and there are millions of miles of pipes and associated infrastructure used to transport it directly to peoples' homes. The complexity and cost for retrofitting hundreds of millions of homes and electrifying all the associated appliances is immense, not to mention all the backlash you get from people who love their gas stoves and grills. If we could just switch to generating renewable methane it would be a huge win in terms of logistical simplicity and would minimize disruption to peoples' day to day lives, which would probably make folks a lot more willing to accept it without putting up a huge fight.
  - kibwen 3y ago
    > The complexity and cost for retrofitting hundreds of millions of homes and electrifying all the associated appliances is immense This is overselling the difficulty. What you're saying is true, but you don't need to rip out functioning appliances. Appliances have a finite service lifetime; once they fail, replace them with electrified appliances. Already here in the year 2023, I wouldn't dream of building a house with a gas stove or gas heating. Induction stoves are just plain better than gas stoves, and heat pumps are cheaper than gas heating once you factor in that the gas-heated house will need a separate AC installation for cooling, whereas the heat-pump house won't. These days, methane doesn't make sense anywhere except at the power generation end, and power generation sources are fungible and can be gradually replaced on their own schedule.
- BobbyJo 3y ago
  Not really. The reason coal was so popular was because you didn't really need any specialized infrastructure. It is a solid you can just ship using the same trains and trucks you use for TVs and apples. So you're really only giving up the mines and power plants.
  - kibwen 3y ago
    This seems to be arguing that the existence of natural gas pipe infrastructure is somehow a benefit of natural gas, rather than a downside. The pipes are an expense, to say nothing of the fact that even our best-maintained pipes are leaking 2% of their gas directly into the atmosphere per year (the worst are leaking double or triple that). A hunk of coal that falls off a truck doesn't contribute to emissions; a leaky methane pipe does, which can actually make natgas plants overall worse for emissions than coal.
    - BobbyJo 3y ago
      Not at all. In another comment I make a similar statement to yours, I'm just pointing out that the coal:methane comparison doesn't make sense.
    - ZeroGravitas 3y ago
      Coal mining is also a major source of methane emissions: https://www.iea.org/reports/global-methane-tracker-2023/strategies-to-reduce-emissions-from-coal-supply https://www.iea.org/reports/global-methane-tracker-2023/stra...
BobbyJo 3y ago
> There's got to be tens of trillions of dollars in deployed methane infrastructure Highly doubt it is worth that much presently, so even if the investment was that large (which I doubt) we certainly aren't looking at walking away from that much presently. The big reason to move away from methane is that gas delivery infrastructure is expensive to maintain, and nearly impossible to keep leak free. Reusing existing infrastructure implies investing in its maintenance, which may be more expensive than building new infrastructure for liquid fuel (which itself already exists).
hannob 3y ago
The thing is: Most of that infrastructure is obsolete in any case. These synthetic chemicals will play a role in industry and shipping, probably also in long-duration storage. But they won't be in widespread use like fossil gas today. They're just too inefficient.

foxyv 3y ago

The problem with hydrogen is the storage. Although electrolysis and other methods of generating hydrogen are fairly efficient, the cost to compress it is obscene. Sabatier production of Methane is comparable, however we already have infrastructure to use Methane and storage is a solved problem. Methanol production requires methane as a synthesis gas so it just adds another step. Plant based methanol has all the same problems as ethanol. Until we are running electrified tractors and equipment we will probably be carbon positive when producing methanol. There are a few processes which are using waste from coal and concrete plants, but they are unlikely to scale enough to make Methane unnecessary. Currently the best way to store surplus electricity are batteries and pumped hydro.

pfdietz 3y ago
For static applications, hydrogen can be easily stored underground. Energy is used to compress it, but that energy can be recovered by running it through an expander (and if the compression/expansion is done in stages to approximate isothermal compression, the round trip efficiency of this can be high.)
- foxyv 3y ago
  That's really neat! I've mostly seen explanations about Hydrogen as a vehicle fuel so I've never stumbled on cavern storage. It makes sense to use isothermal compression. Especially if you can recover the energy from decompressing the hydrogen using a turbo expander which would be obscenely difficult on a vehicle.
  - _hypx 3y ago
    Why would it be difficult in a car? It is the same principle as a compressed air car: https://en.wikipedia.org/wiki/Compressed-air_car https://en.wikipedia.org/wiki/Compressed-air_car
    - foxyv 3y ago
      A turboexpander in a car would add an obscene amount of cost to an already expensive fuel cell vehicle. Also, it would be a fire and explosion hazard requiring a ton of maintenance.

narag 3y ago

Making any type of chemical energy carrier comes with substantial losses The goal presented in the article seems to be cleaning the atmosphere, not generating chemicals. So H2 and ammonia would be irrelevant. And it's not so much about maximazing efficiency as not losing too much. The alternative should be other carbon-based chemicals, as useful as methane, needed in huge volumes and with a practical process of extraction using solar panels. Is there something like that? Also, is there another product with the same characteristics with methane as a starting point?

slashdev 3y ago
That’s nonsensical, because you burn the methane and put the carbon right back into the atmosphere. It didn’t clean anything. It’s merely a carbon neutral form of chemical energy. H2, ammonia, methanol would be just as carbon neutral.
- narag 3y ago
  Well, it's there in the title of the article, so don't shoot me. If the premise of the article is bs, it doesn't make sense to discuss efficiency. Is it nonsensical though? IDK, it seems somehow better than extracting the gas from the ground and adding it to the system. Also if there's another more complex chemical not for burning, that you can synthesize from the methane, it would be a net gain.
  - slashdev 3y ago
    It’s much better than extracting it from the ground, hence carbon neutral. It is not carbon negative though. The article was reasonably well written, but I can see how you’d draw that conclusion if you only read the title.

NickM 3y ago

the first one you will look at is hydrogen, because it's the simplest Simplest chemically != simplest to use in practice. There are already millions of miles of natural gas pipelines leading directly to peoples' homes, and those pipelines cannot be used with hydrogen (not to mention all the appliances they feed). Renewable methane is a dead simple drop-in replacement for natural gas. None of the other alternatives you mentioned share that property, and I think you're seriously under-weighting the importance of it.

hannob 3y ago
None of these chemicals will be used in people's homes in any meaningful quantity. That's just not going to happen due to the conersion inefficiencies.
- pfdietz 3y ago
  Right. The more efficient way to use methane to heat a home (vs. current furnaces) is to burn it in a CC power plant and heat the home with a heat pump.
  - NickM 3y ago
    Yes, that would be more efficient, but there are so many edge cases where switching an existing home to use heat pumps is prohibitively difficult or expensive. Maybe you have radiators that require higher temps than can be efficiently produced by heat pumps. Maybe you live in a place where the air gets too cold for air source heat pumps to be cost effective. Maybe you want to install ground source, but you live in a city and don't have a big enough yard. Maybe you have a big enough yard but local geological conditions aren't conducive to digging deep enough. Not to mention all the people who just don't want to bother switching, or who don't have the money to switch, or prefer the reliability of the natural gas over the electrical grid, or...etc. Or just look at the culture wars that are already starting over gas stoves, when nobody has even been required to get rid of their existing gas stove, and people are just talking about changing the rules for new construction. There are just so many edge cases where it's hard to get people to switch off natural gas. If we can make green methane, all those problems are simultaneously solved with zero disruption to anyone's homes/lifestyles/etc.

perlgeek 3y ago

Once thing that's missing (from both the article here, and for example the whole hydrogen discussion in Germany) is the round-trip efficiency. Now the author of the article would likely argue that with prices dropping as fast as they do, a 60% efficiency is just a few years delay away from being economically efficient. (A quick search came up with a 68% efficiency for fuel cells and "80% - 95%" for electrolysis, putting the whole thing at 54%-65%) But I can't help but think we'll come up with something a bit more efficient, because that'll be more viable sooner, and more profitable in the long run.

pfdietz 3y ago
The relevant applications for hydrogen are ones where efficiency doesn't much matter (long term storage, rare event grid backup). What matters is minimizing capital cost, which probably means using combustion turbines, not fuel cells.

AlanSE 3y ago

I've been following Terraform Industries for a while, and it does strike me as obvious that H2 will be the preferred form of energy storage medium in the long run, not just an intermediate species. Depending on the conditions, if you're doing day-night energy storage, then you would like to fill up the H2 tank and then burn it when demand ramps up. The only role I see for methane is when your H2 tank is already filled up but your solar panels are still producing. This is not just possible, but deterministically required whenever solar gets deployed enough for seasonal storage to be necessary. Right now California is something like 35% solar + wind energy, and the "duck curve" is nearly maxing out. This was predicted in extreme specificity 20 years ago, as >30% and you get stuff like zeroed-out energy prices during the day. We have not solved the day-night (daily) energy storage problem, which only requires storing energy for a matter of hours. When you go to something like 60% renewables, then even crazier stuff happens. Overproduction during sunny times goes bananas and (assuming daily storage is solved, which it isn't) seasonal issues start to arise. I don't think H2 will ever work for seasonal storage, although I think it's fine for multi-day storage scenarios. It's not theoretically impossible, I just compare to the equivalent that we have for natural gas and realize you would need MANY TIMES that level of investment to save the same amount of energy in H2. Plus, fossil fuel gas producers are mostly at a constant level, whereas solar production outright needs summer-to-winter storage. What I don't buy is that these units will be disconnected from the grid and be economical by their gas products. No way, no how. What you want is to run the chemicals plant with low-voltage solar power locally, and trade-off with the grid as is economical.

rasz 3y ago
>Right now California is something like 35% solar + wind energy, and the "duck curve" is nearly maxing out. This was predicted in extreme specificity 20 years ago Legislated. Its easy to predict something if you write it into law resulting in shutdown of Nuclear power station (Diablo Canyon) >The main driver deterring PG&E from seeking a 20-year operating licence extension is the 2015 renewable portfolio standard (RPS) of producing 50% of its electricity from qualified renewable energy sources by 2030. PG&E’s model for the future cost of operating Diablo Canyon indicated that the cost per kilowatt hour was going to almost double, since the company would be forced to lower the amount of power it could produce from the plant in order to meet the state’s requirement. Dropping the capacity factor from the current 92% to say 50% would virtually double the price per kilowatt hour since costs are largely fixed. >The state law which effectively dictates that by 2030 Diablo Canyon should operate at lower capacity each year and buy in power from intermittent renewables has apparently sealed the fate of the plant.