10 ms·

I'll admit I really don't get the fascination with hydrogen as an energy storage medium. It has to be manufactured, so how green it is depends on whatever the p

by xoa 6y ago

I'll admit I really don't get the fascination with hydrogen as an energy storage medium. It has to be manufactured, so how green it is depends on whatever the power input is coming from. It's not any inherently greener then synthetic hydrocarbon production, which can be produced from atmospheric carbon for zero net carbon impact, and of course has no sulfur or aromatics. It also works fine with existing engineering. And hydrogen is an absolute total bitch to work with. It's got bad density, a really low/really high pressure liquidation point, escapes from everything, embrittles steel, and on and on. The infrastructure has no multiple use, unlike improvements to the grid. So why not just do full manufacture of regular fuel? I've never understood where hydrogen fits between improving batteries/capacitors and synthetic hydrocarbons. It always seemed like an answer without a question outside of rockets (and even there the economics and practicalities of methalox may be better).

aeternum 6y ago
It sounds futuristic though and the exhaust is water!
Yetanfou 6y ago
An advantage of hydrogen is that it can be used in fuel cells, producing only water as reaction product. Using hydrocarbons of any sort in existing engines leads to the production of nitrogen oxides due to the presence of nitrogen in the air.
- xoa 6y ago
  Thanks for this reply as well. But batteries will cover most land use, and going by sources like the EIA [1] the primary source of anthropogenic N2O emissions is overwhelmingly agriculture, at 70+%. Other sources indicate that may have fallen somewhat since then, but even so everything I can find indicates fossil fuel combustion is still only around 10%. And of that air travel will be single digits. Not nothing, but I'm not sure it'd justify massive effort alone.
  - Yetanfou 6y ago
    I don't think hydrogen is a good energy storage solution. I do see its advantage over hydrocarbons for certain applications but the difficulties in storing hydrogen - a small molecule which is sort of an escape artist - make it less than ideal for many purposes. Fuel cells can get contaminated unless they're run with pure hydrogen and oxygen. In applications where hydrogen is already available - e.g. H₂-LOX fuelled rockets - it makes sense to use fuel cells. It might be possible to run aircraft using H₂-fed fuel cells if these can be made powerful and light enough to fit the application, the advantage over battery-electric here is that the energy density of liquid hydrogen is much higher than that of current battery technology. For the rest - cars being a good example - I think batteries are currently a better solution. Large scale energy storage is probably handled better using either redox flow batteries [1], hydro storage systems or energy storage vaults using concrete blocks which are lifted when there is too much energy available, lowered when energy is needed. [1] https://en.wikipedia.org/wiki/Flow_battery https://en.wikipedia.org/wiki/Flow_battery
schainks 6y ago
This is a simplification, think about this: You can manufacture hydrogen anywhere as long as you have water, an electrolyzer, and a power source. Oil can only be pumped out of the ground in certain places, water is technically _much_ more abundant everywhere. Hydrogen storage tech has improved in the last twenty years. It's becoming affordable and "as safe" to store hydrogen at fuel densities similar to that of petroleum based fuels. Obviously the devil's in the details, but shouldn't we attempt to engineer huge carbon emitters like container shipping or aircraft to run on hydrogen + solar?
- xoa 6y ago
  >You can manufacture hydrogen anywhere as long as you have water, an electrolyzer, and a power source. I don't understand what you're arguing with here? You can manufacture synthetic hydrocarbons anywhere so long as you have water, carbon dioxide, and a power source too. So I'm not sure why you see this as an advantage for hydrogen. >but shouldn't we attempt to engineer huge carbon emitters like container shipping or aircraft to run on hydrogen + solar? Again, why hydrogen from solar vs hydrocarbons from solar? From a global warming perspective what matters is net GHG.
  - mayama 6y ago
    > You can manufacture synthetic hydrocarbons anywhere so long as you have water, carbon dioxide You need coal or some biomass to manufacture synthetic hydrocarbons. And tail emission is still a concern.
    - kolinko 6y ago
      You can extract carbon from atmosphere.
      - gus_massa 6y ago
        Organic reactions to produce complex molecules have an horrible efficiency. (For example, photosynthesis in plants has a 1% or 2% of efficiency.) Perhaps the efficiency to produce methane is not so bad, but a chain with 6 or 7 carbons like gasoline is very complicated. It is not equivalent if they are aligned or they form a ramified structure like a tree, and it is very difficult to choose which one they will form unless you have a very complex process. There are some graphics in https://en.wikipedia.org/wiki/Octane_rating#Isooctane_as_a_reference_standard https://en.wikipedia.org/wiki/Octane_rating#Isooctane_as_a_r...
mattashii 6y ago
> It's not any inherently greener then synthetic hydrocarbon production, which can be produced from atmospheric carbon for zero net carbon impact As I understand it, the production of complex hydrocarbons that can be used as a replacement for jet fuel is even more inefficient when compared to the production of hydrogen, as many of the known processes that start from CO2 actually use hydrogen in the process. So, although you could get energy-denser fuels, that would be at the cost of even more end-to-end efficiency. Finally, hydrogen has a great energy / kg ratio, making it a very interesting fuel for aviation if the material science problems of hydrogen can be overcome, as it allows for longer distance flights / flights with more/heavier cargo.
- xoa 6y ago
  That makes sense. I guess the questions would be whether the material science can really allow us to make use of that, and how the end-to-end efficiency weights against the infrastructure/engineering greenfield costs that synthetic fuels avoid. Being able to just keep using all existing engines/storage/distribution knowledge we already have is a major economic advantage. Electric will cover most land based transportation, and we need negative carbon technology anyway, so de novo hydrogen R&D has less to spread out across. If solar/nuclear becomes cheap enough, less efficient for more convenient might still be a worthwhile trade off. But I guess that's something for experts to crunch out. Thanks for the reply.
  - dcustodio 6y ago
    Don't forget that wind turbines still produce at night when there is less demand. So either you use that power to pump water upstream (if you have dams) or you can use it to produce Hydrogen.
    - dathinab 6y ago
      There is also work underway on solar cells which directly produce hydrogen instead of electricity.
    - nickik 6y ago
Hypx 6y ago
> The infrastructure has no multiple use, unlike improvements to the grid. You need hydrogen for steel production, ammonia, and synthetic hydrocarbon production. Likely cement, glass, and plastic production too. > So why not just do full manufacture of regular fuel? I've never understood where hydrogen fits between improving batteries/capacitors and synthetic hydrocarbons. Because fuel cells are batteries themselves, and synthetic hydrocarbon needs hydrogen.
usrusr 6y ago
Manufactured fuels have two main economies: one is energy input per energy output (usually bigger than one and the goal is to get that number as close to one as possible) and the other is transformer system cost, particularly cost that even applies when idle. If this number is very high fuel manufacturing won't be opportunistic at all and will keep the conversion systems at high utilization, offering input energy prices as needed and selling at prices depending on demand. A very low investment/idleness cost on the other hand would lead to wildly variable utilization depending on output demand and input availability. Hydrogen is usually considered a very simple conversation (e.g. compared to synthetic hydrocarbons) that would be very open to opportunistic transformation utilization. "Only fire up the converters when there's an open order for synfuel and the grid has excess power", that's the dream. I'm not convinced that this dream is significantly more viable for simple hydrogen than for more complex synfuels (particularly factoring in the many ways hydrogen isn't easy to store), but I can easily see how some people might want to believe that.
- ncmncm 6y ago
  With the advent of cheap aerogels, LH2 is much easier to store than it once was.
sergeykish 6y ago
> The infrastructure has no multiple use Hydrogen solves long term storage for electricity generation and heating (winter time) https://model.energy/ https://model.energy/
jillesvangurp 6y ago
Well the answer to that is that it is not that simple. We know how synthesize hydrogen and scale it and what it will cost because companies are already doing that today. Synthesizing other fuels may be long term feasible but are simply not commonly done right now. More importantly, there don't seem to be many companies planning to do that right now. Airbus is not in the business of producing fuel so it would need such a company to step up and do it before they can start designing products for it. E.g. liquid methane would be a good alternative for hydrogen. The appeal of both hydrogen and methane would be that converting engines to burn it seems doable and given that rockets can use either as propellant there is no question about their suitability as a fuel from an efficiency point of view. The difference of course is that with methane it would end up coming from fossil reserves which from the point of view going carbon neutral kind of defeats the purpose of making these planes carbon neutral. Swapping out kerosene for methane kind of just moves that problem. IMHO it's still worth exploring (and some companies have actually done that). Also, I imagine synthetic methane is eventually going to happen and kill the market for natural gas. Just not in the next decades. The key here is a combination of becoming carbon neutral and doing it in a cost effective and timely way. Synthetic methane may or may not actually become a thing but the simple reality is that it's an industry that simply does not currently exist. Clean hydrogen production on the other hand exists today (at small scale) and seems to be on a feasible path to scaling in the next 15 years or so. Additionally hydrogen infrastructure is something that is attracting lots of investment currently. Airbus is targeting a launch in the mid to late 2030's. So they need to be targeting a fuel source that they can reasonably expect to have some supply for by then so they can actually fuel the planes where-ever they need to fly. So the supply and infrastructure for hydrogen are not a certainty but at least on a path where it could be there in 15 years. The rest is just solving engineering problems. They seem to believe they can do it.
Kosirich 6y ago
It's difficult to tell how they will deal with hydrogen as they don't even try to address all the points you have made. The articles available just say "hydrogen stored in tank under the wing". Seems investors in green tech. will be betting on both technologies aka having facilities that can both produce hydrogen and synt. fuels. https://www.energyglobal.com/special-reports/28082020/haldor-topsoe-joins-danish-sustainable-fuel-project/ https://www.energyglobal.com/special-reports/28082020/haldor... https://www.engineering.com/ElectronicsDesign/ElectronicsDesignArticles/ArticleID/20738/Siemens-Kicks-Off-Wind-to-Hydrogen-Project-in-Denmark.aspx https://www.engineering.com/ElectronicsDesign/ElectronicsDes...
hannob 6y ago
> So why not just do full manufacture of regular fuel? Always fascinating when people use "just" in sentences where they propose something that hasn't been done before (at least not at any scale that would matter) and that is a huge challenge. As for the reason, my understading is that producing fuels from electricity is just very inefficient. You still use hydrogen as the first step and then add other steps to produce hydrocarbons. Using hydrogen spares a few conversion steps and you'll need less electricity (but likely still a lot).
- Qwertious 6y ago
  "Just" is a great example of a word carrying more subtext than text. "It's just a stabbing."
leoedin 6y ago
Getting the carbon is a huge problem. Atmospheric CO2 is at something like 400ppm - that's 0.04% of air. Given that most hydrocarbons contain a fairly large amount of carbon, that means you have to process a huge amount of air to get the CO2 needed for your fuel. That's before all the other process inefficiencies. I agree hydrogen isn't the best fuel, but the round trip efficiency of any other synthesised hydrocarbon must be an order of magnitude lower - and even if solar energy is abundant, it's not so abundant we can waste 90%+ of it on process inefficiencies.

by xoa 6y ago

aeternum 6y ago

It sounds futuristic though and the exhaust is water!

Yetanfou 6y ago

An advantage of hydrogen is that it can be used in fuel cells, producing only water as reaction product. Using hydrocarbons of any sort in existing engines leads to the production of nitrogen oxides due to the presence of nitrogen in the air.

xoa 6y ago
Thanks for this reply as well. But batteries will cover most land use, and going by sources like the EIA [1] the primary source of anthropogenic N2O emissions is overwhelmingly agriculture, at 70+%. Other sources indicate that may have fallen somewhat since then, but even so everything I can find indicates fossil fuel combustion is still only around 10%. And of that air travel will be single digits. Not nothing, but I'm not sure it'd justify massive effort alone.
- Yetanfou 6y ago
  I don't think hydrogen is a good energy storage solution. I do see its advantage over hydrocarbons for certain applications but the difficulties in storing hydrogen - a small molecule which is sort of an escape artist - make it less than ideal for many purposes. Fuel cells can get contaminated unless they're run with pure hydrogen and oxygen. In applications where hydrogen is already available - e.g. H₂-LOX fuelled rockets - it makes sense to use fuel cells. It might be possible to run aircraft using H₂-fed fuel cells if these can be made powerful and light enough to fit the application, the advantage over battery-electric here is that the energy density of liquid hydrogen is much higher than that of current battery technology. For the rest - cars being a good example - I think batteries are currently a better solution. Large scale energy storage is probably handled better using either redox flow batteries [1], hydro storage systems or energy storage vaults using concrete blocks which are lifted when there is too much energy available, lowered when energy is needed. [1] https://en.wikipedia.org/wiki/Flow_battery https://en.wikipedia.org/wiki/Flow_battery

schainks 6y ago

This is a simplification, think about this: You can manufacture hydrogen anywhere as long as you have water, an electrolyzer, and a power source. Oil can only be pumped out of the ground in certain places, water is technically _much_ more abundant everywhere. Hydrogen storage tech has improved in the last twenty years. It's becoming affordable and "as safe" to store hydrogen at fuel densities similar to that of petroleum based fuels. Obviously the devil's in the details, but shouldn't we attempt to engineer huge carbon emitters like container shipping or aircraft to run on hydrogen + solar?

xoa 6y ago
>You can manufacture hydrogen anywhere as long as you have water, an electrolyzer, and a power source. I don't understand what you're arguing with here? You can manufacture synthetic hydrocarbons anywhere so long as you have water, carbon dioxide, and a power source too. So I'm not sure why you see this as an advantage for hydrogen. >but shouldn't we attempt to engineer huge carbon emitters like container shipping or aircraft to run on hydrogen + solar? Again, why hydrogen from solar vs hydrocarbons from solar? From a global warming perspective what matters is net GHG.
- mayama 6y ago
  > You can manufacture synthetic hydrocarbons anywhere so long as you have water, carbon dioxide You need coal or some biomass to manufacture synthetic hydrocarbons. And tail emission is still a concern.
  - kolinko 6y ago
    You can extract carbon from atmosphere.
    - gus_massa 6y ago
      Organic reactions to produce complex molecules have an horrible efficiency. (For example, photosynthesis in plants has a 1% or 2% of efficiency.) Perhaps the efficiency to produce methane is not so bad, but a chain with 6 or 7 carbons like gasoline is very complicated. It is not equivalent if they are aligned or they form a ramified structure like a tree, and it is very difficult to choose which one they will form unless you have a very complex process. There are some graphics in https://en.wikipedia.org/wiki/Octane_rating#Isooctane_as_a_reference_standard https://en.wikipedia.org/wiki/Octane_rating#Isooctane_as_a_r...

mattashii 6y ago

> It's not any inherently greener then synthetic hydrocarbon production, which can be produced from atmospheric carbon for zero net carbon impact As I understand it, the production of complex hydrocarbons that can be used as a replacement for jet fuel is even more inefficient when compared to the production of hydrogen, as many of the known processes that start from CO2 actually use hydrogen in the process. So, although you could get energy-denser fuels, that would be at the cost of even more end-to-end efficiency. Finally, hydrogen has a great energy / kg ratio, making it a very interesting fuel for aviation if the material science problems of hydrogen can be overcome, as it allows for longer distance flights / flights with more/heavier cargo.

xoa 6y ago
That makes sense. I guess the questions would be whether the material science can really allow us to make use of that, and how the end-to-end efficiency weights against the infrastructure/engineering greenfield costs that synthetic fuels avoid. Being able to just keep using all existing engines/storage/distribution knowledge we already have is a major economic advantage. Electric will cover most land based transportation, and we need negative carbon technology anyway, so de novo hydrogen R&D has less to spread out across. If solar/nuclear becomes cheap enough, less efficient for more convenient might still be a worthwhile trade off. But I guess that's something for experts to crunch out. Thanks for the reply.
- dcustodio 6y ago
  Don't forget that wind turbines still produce at night when there is less demand. So either you use that power to pump water upstream (if you have dams) or you can use it to produce Hydrogen.
  - dathinab 6y ago
    There is also work underway on solar cells which directly produce hydrogen instead of electricity.
  - nickik 6y ago

Hypx 6y ago

> The infrastructure has no multiple use, unlike improvements to the grid. You need hydrogen for steel production, ammonia, and synthetic hydrocarbon production. Likely cement, glass, and plastic production too. > So why not just do full manufacture of regular fuel? I've never understood where hydrogen fits between improving batteries/capacitors and synthetic hydrocarbons. Because fuel cells are batteries themselves, and synthetic hydrocarbon needs hydrogen.

usrusr 6y ago

Manufactured fuels have two main economies: one is energy input per energy output (usually bigger than one and the goal is to get that number as close to one as possible) and the other is transformer system cost, particularly cost that even applies when idle. If this number is very high fuel manufacturing won't be opportunistic at all and will keep the conversion systems at high utilization, offering input energy prices as needed and selling at prices depending on demand. A very low investment/idleness cost on the other hand would lead to wildly variable utilization depending on output demand and input availability. Hydrogen is usually considered a very simple conversation (e.g. compared to synthetic hydrocarbons) that would be very open to opportunistic transformation utilization. "Only fire up the converters when there's an open order for synfuel and the grid has excess power", that's the dream. I'm not convinced that this dream is significantly more viable for simple hydrogen than for more complex synfuels (particularly factoring in the many ways hydrogen isn't easy to store), but I can easily see how some people might want to believe that.

ncmncm 6y ago
With the advent of cheap aerogels, LH2 is much easier to store than it once was.

sergeykish 6y ago

> The infrastructure has no multiple use Hydrogen solves long term storage for electricity generation and heating (winter time) https://model.energy/ https://model.energy/

jillesvangurp 6y ago

Well the answer to that is that it is not that simple. We know how synthesize hydrogen and scale it and what it will cost because companies are already doing that today. Synthesizing other fuels may be long term feasible but are simply not commonly done right now. More importantly, there don't seem to be many companies planning to do that right now. Airbus is not in the business of producing fuel so it would need such a company to step up and do it before they can start designing products for it. E.g. liquid methane would be a good alternative for hydrogen. The appeal of both hydrogen and methane would be that converting engines to burn it seems doable and given that rockets can use either as propellant there is no question about their suitability as a fuel from an efficiency point of view. The difference of course is that with methane it would end up coming from fossil reserves which from the point of view going carbon neutral kind of defeats the purpose of making these planes carbon neutral. Swapping out kerosene for methane kind of just moves that problem. IMHO it's still worth exploring (and some companies have actually done that). Also, I imagine synthetic methane is eventually going to happen and kill the market for natural gas. Just not in the next decades. The key here is a combination of becoming carbon neutral and doing it in a cost effective and timely way. Synthetic methane may or may not actually become a thing but the simple reality is that it's an industry that simply does not currently exist. Clean hydrogen production on the other hand exists today (at small scale) and seems to be on a feasible path to scaling in the next 15 years or so. Additionally hydrogen infrastructure is something that is attracting lots of investment currently. Airbus is targeting a launch in the mid to late 2030's. So they need to be targeting a fuel source that they can reasonably expect to have some supply for by then so they can actually fuel the planes where-ever they need to fly. So the supply and infrastructure for hydrogen are not a certainty but at least on a path where it could be there in 15 years. The rest is just solving engineering problems. They seem to believe they can do it.

Kosirich 6y ago

It's difficult to tell how they will deal with hydrogen as they don't even try to address all the points you have made. The articles available just say "hydrogen stored in tank under the wing". Seems investors in green tech. will be betting on both technologies aka having facilities that can both produce hydrogen and synt. fuels. https://www.energyglobal.com/special-reports/28082020/haldor-topsoe-joins-danish-sustainable-fuel-project/ https://www.energyglobal.com/special-reports/28082020/haldor... https://www.engineering.com/ElectronicsDesign/ElectronicsDesignArticles/ArticleID/20738/Siemens-Kicks-Off-Wind-to-Hydrogen-Project-in-Denmark.aspx https://www.engineering.com/ElectronicsDesign/ElectronicsDes...

hannob 6y ago

> So why not just do full manufacture of regular fuel? Always fascinating when people use "just" in sentences where they propose something that hasn't been done before (at least not at any scale that would matter) and that is a huge challenge. As for the reason, my understading is that producing fuels from electricity is just very inefficient. You still use hydrogen as the first step and then add other steps to produce hydrocarbons. Using hydrogen spares a few conversion steps and you'll need less electricity (but likely still a lot).

Qwertious 6y ago
"Just" is a great example of a word carrying more subtext than text. "It's just a stabbing."

leoedin 6y ago

Getting the carbon is a huge problem. Atmospheric CO2 is at something like 400ppm - that's 0.04% of air. Given that most hydrocarbons contain a fairly large amount of carbon, that means you have to process a huge amount of air to get the CO2 needed for your fuel. That's before all the other process inefficiencies. I agree hydrogen isn't the best fuel, but the round trip efficiency of any other synthesised hydrocarbon must be an order of magnitude lower - and even if solar energy is abundant, it's not so abundant we can waste 90%+ of it on process inefficiencies.