4 ms·

> When it is genuinely green, it is obtained through electrolysis, a process that is only 70% to 80% efficient. That's not bad compared to internal combustion e

> When it is genuinely green, it is obtained through electrolysis, a process that is only 70% to 80% efficient. That's not bad compared to internal combustion engines (ICEs), but fuel cell detractors use that to bash them anyway. Scientists at Tel Aviv University plan to kill that argument with a method that is over 90% efficient in generating green hydrogen. This is highly disingenuous. The problem isn't just that electrolysis isn't 100% efficient. It's that the electrolysis and the compression and the transmission and the distribution and the fuel cell all have efficiency problems, and are all much more expensive that the alternative (straight electric).

mustafa_pasi 3y ago
The obsession with efficiency is disingenuous too. The two limiting factors are generation capacity and cost/economics. Efficiency by itself says nothing. In the early 1900s, gas was less efficient than electricity too, but for a whole century gasoline powered transportation was more feasible. Aviation is still only feasible with kerosene despite it being less efficient than electric propulsion.
- bkor 3y ago
  Efficiency has a huge impact on the cost/economics, something that you've highlighted. If significant more energy is needed, it'll likely be more expensive. Hydrogen is sometimes only a third as efficient as other solutions. It's pretty logical to assume it'll be > In the early 1900s, gas was less efficient than electricity too I think you mean gasoline instead of just gas. Hydrogen requires huge amounts of energy before it's easy to transport, which is what you responded to. In any case, in the early 1900s, gasoline had a huge amount of stored energy. It was a matter of using it efficiently, you're comparing apples to oranges. With Green Hydrogren too often people say that some technological improvement will solve the drawbacks. While ignoring that for e.g. hydrogen it's not so easy, for other options it is/was. Same for the often suggested "solution" of using surplus energy. A factory that doesn't work 24/7 is more costly. Aside from that I understood that hydrogen is best produced continuously for it to be efficient.
  - mustafa_pasi 3y ago
    >Efficiency has a huge impact on the cost/economics Not in the way that you think, no. For all intents and purposes, we have limitless energy. The problem was never that we don't have enough capacity, because we can scale capacity as much as we want. The only thing that is required is that energy generation (i.e. $/kWh) is cheap enough, and this seems feasible with solar and wind and maybe fission and later one fusion or other sources. >you're comparing apples to oranges You are the one saying, "just attach a transmission line to it" or "just put a battery in it", without thinking of all the cases where this is just not possible. Nobody is arguing that you should start powering your toaster with hydrogen. You all are attacking a strawman, it seems.
    - sitkack 3y ago
      You would have to solve the problem of getting soggy toast from the exhaust steam.
      - angiosperm 3y ago
        Unscheduled detonations would put an, er, damper on adoption.
        sitkack 3y ago
        I believe that would be toast toast.
  - someplaceguy 3y ago
    > Efficiency has a huge impact on the cost/economics It doesn't have nearly as much impact as other factors, such as abundance of the material, how easy/practical it is to work with it (which influences both demand and supply), whether mass infrastructure for it already exists (although this is more relevant in the short-term rather than long-term), etc. These factors impact the economics of an energy source much more than efficiency, and economics is by far the most important factor in deciding whether an energy source will be used or not (and how much of it), not efficiency. e.g. if hydrogen is only 10% efficient but there's 10 times more of it on Earth compared to a similar energy source that is 90% efficient, then hydrogen wins (all other factors being equal). As another example, if hydrogen tanks in cars explode 100 times as often as gas tanks, then it would probably be a complete non-starter for powering vehicles, regardless of efficiency.
- mrpopo 3y ago
  Not really, increasing energy efficiency is at the heart of many climate solutions. Clean energy is still scarce, and in the places where it isn't, for instance Germany, there is backlash against it. Not to mention that they aren't even close to being 100% renewable-powered (wind+solar 30%), not even close to have 100% EV market penetration (about 2%), not even close to have the theoretical capacity for a grid to power 100% EVs, and you would like to adopt a less efficient technology that would require to double the clean power needs compared to EVs...
  - mustafa_pasi 3y ago
    Manufacturing a whole new vehicle with a huge ass battery that is more cost intensive to manufacturing than a comparable ICE, a vehicle that due to contemporary trends has to be a 5-ton lifted SUV, a vehicle that is going to be used by ONE person to commute to work along a fixed predetermined route, a vehicle that is going to be replaced after 3 years because this person have to have the newest four wheels on the lot to project status to attract a status obsessed mate, all that is ALSO EXTREMELY energy inefficient. If you truly cared about energy efficiency you'd proposition the ban or severe limitation of private car usage in sufficiency dense localities. Public trams and busses, cycling, walking, and maybe even very small private vehicles would be extremely more energy efficient. There is nothing about a 5-ton EV SUV that says energy efficiency.
    - _aavaa_ 3y ago
      That's a criticism of trends in automobiles (which I agree with) not something inherent to BEVs. Guess what, if you get a BEV with 1/3-1/4 the battery size, the range is smaller, but for most people it will be fine. And now your vehicle is not lugging around all that excess weight. And do you really need a massive electric pickup truck? It's absolutely possible, but I bet for most people it's a preference.
    - mrpopo 3y ago
      Obviously reducing private car usage is a priority. I don't have a car, never owned one, and I'm absolutely in favour of severe restrictions. Now, you have to acknowledge the world we live in, a total ban won't be feasible in the time-frame that we have to combat climate change. (And neither will an electric grid sufficiently powerful to power millions of green hydrogen-powered vehicles or 5-ton SUVs for that matter). Not all EVs weigh 5 tons. Promoting (smaller) EVs for people who need them is a good thing.
- _aavaa_ 3y ago
  Yes, gasoline won because it was more convenient. Hydrogen (and explosive gas which is notorious difficult to transport and work with safely) is neither efficient nor convenient.
- kakwa_ 3y ago
  Efficiency gains can even very well be detrimental to resource consumption. Efficiency gains generally lead to lower cost, which in turn lead to higher demand. And this increased demand can very well be in excess of the efficiency gain. This was observed as early as the 1860ies and theorized in concepts like the Jevons Paradox/Rebound Effect. This doesn't mean efficiency gains are not desirable, but they must be implemented in conjunction with other factors like environmental policies. https://en.wikipedia.org/wiki/Jevons_paradox https://en.wikipedia.org/wiki/Jevons_paradox https://en.wikipedia.org/wiki/Rebound_effect_(conservation) https://en.wikipedia.org/wiki/Rebound_effect_(conservation)
  - _aavaa_ 3y ago
    It's true, but that isn't a given. For example, it won't matter how cheap and efficient LEDs are, people aren't going to keep adding them to their house.
    - kakwa_ 3y ago
      Indeed, this effect is not a given, specially if the resource is scarce to begin with. But regarding your example, personally, I'm actually kind of "keep adding light bulbs" thanks to LEDs. I'm no longer using one central 75W incandescent bulb per room, but rather 4 or 5 Philips Hue lights (bulbs & led strips) in an indirect fashion. Hue bulbs & these new usages would not have existed without the LED efficiency gains. This counter example, of course, has many flaws, firstly, it's only my specific situation, not an average case. The efficiency gains (energy and longevity) is only part of what enabled these new types of lights. And lastly, I think my energy consumption is still lower non-the-less. But it demonstrate how things might not be so clear cut.
hkt 3y ago
100% this. Few people have been able to answer the question of "how does it compare to a heat pump that has a SCOP of 4?" without me having to fight the urge to roll my eyes. By the time (highly explosive) hydrogen gets into people's homes I'd be surprised if it was even 20% as efficient as a heat pump.
- wffurr 3y ago
  You would use hydrogen to produce methane to then burn in people's existing as furnaces using the existing natural gas distribution infrastructure. That seems to be Terraform's plan. Still seems better to me to convert as much housing as possible to heat pumps, which seem much better fit for purpose than on-site combustion. I think green hydrogen has a lot more potential as a precursor to liquid fuels for e.g. aviation and shipping, which otherwise will be extremely difficult to electrify.
  - _aavaa_ 3y ago
    If you're going to convert it into methane and burn it you'll make a fuel cell's ~37% round trip efficiency look massive. turning it into methane to burn it is trying to solve last century's problem. People need way to stay warm not things to burn.
    - wffurr 3y ago
      I think their point for syngas (or better yet synthetic liquid fuels) is that solar will be so cheap that the efficiency won't matter.
      - hkt 3y ago
        Except that efficiency really does matter right now as energy demands are increasing globally
aredox 3y ago
I concur: Hydrogen is a "bad" fuel in terms of practicality: it's extremely reactive and it leaks easily. To make a parallel with rocket science: there are extremely efficient liquid chemical propellants, much better than what is in use today, like Chlorine Trifluoride, that nobody uses anymore because they are just too dangerous to work with. Or the fact that hydrogen airships will never come back: nobody will ever, ever switch from helium despite the cost and lift difference. Hydrogen has its uses (e.g. steel plants). Transportation is not one of them.
- arijun 3y ago
  I was curious about Chlorine Trifluoride as a propellant, and I found this quote of John D Clark on the Wiki page (hypergolic means it will ignite spontaneously): > It is, of course, extremely toxic, but that's the least of the problem. It is hypergolic with every known fuel, and so rapidly hypergolic that no ignition delay has ever been measured. It is also hypergolic with such things as cloth, wood, and test engineers, not to mention asbestos, sand, and water—with which it reacts explosively. It can be kept in some of the ordinary structural metals—steel, copper, aluminum, etc.—because of the formation of a thin film of insoluble metal fluoride that protects the bulk of the metal, just as the invisible coat of oxide on aluminum keeps it from burning up in the atmosphere. If, however, this coat is melted or scrubbed off, and has no chance to reform, the operator is confronted with the problem of coping with a metal-fluorine fire. For dealing with this situation, I have always recommended a good pair of running shoes
  - wffurr 3y ago
    Ignition! - a history of rocket fuels - from which this quote originates - is freely available online and an excellent read: https://library.sciencemadness.org/library/books/ignition.pdf https://library.sciencemadness.org/library/books/ignition.pd...
- dabluecaboose 3y ago
  >Hydrogen has its uses (e.g. steel plants). Transportation is not one of them. Small caveat, hydrogen is still pretty useful for upper stage rocket propulsion because of its low mass and high specific impulse.
rcme 3y ago
It actually doesn’t have to do with transmission at all. Rather, when you pay for electrolysis, you’re paying for all the energy inputs. When you burn fossil fuels, you’re not paying for any of the energy inputs (hundreds of millions of years of solar radiation). So it’s not surprising that fossil fuels are cheaper even if they’re less efficient.
- _aavaa_ 3y ago
  Firstly I don't see how that follows. You still need to pay to transport both the oil and the hydrogen from where you make it to where you use it. Most importantly, you're not (in most places) paying for the pollution of the atmosphere. E.g. Prices on carbon are nowhere near the level of societal harm that putting it into the atmosphere causes.
  - rcme 3y ago
    My point is that to produce hydrogen via electrolysis, you need to input energy. Due to thermodynamics, you can only ever hope to get 0.9 units for each unit of input energy. With fossil fuels, you don’t need to input energy to get them. At least not in the same way. You can run a pump to pump them out of the ground. For each unit of energy that goes into the pump, you likely get 1000x units of energy out.
    - _aavaa_ 3y ago
      I get what you mean. That will really depend on where you get the oil from. Some places need a lot more downstream processing (looking at alberta oil sands) to get something useable than others (the middle east). Whether you want to consider that analogous to the electrolysis step or to another one is not clear since the processes don't map one to one.

mustafa_pasi 3y ago

The obsession with efficiency is disingenuous too. The two limiting factors are generation capacity and cost/economics. Efficiency by itself says nothing. In the early 1900s, gas was less efficient than electricity too, but for a whole century gasoline powered transportation was more feasible. Aviation is still only feasible with kerosene despite it being less efficient than electric propulsion.

bkor 3y ago
Efficiency has a huge impact on the cost/economics, something that you've highlighted. If significant more energy is needed, it'll likely be more expensive. Hydrogen is sometimes only a third as efficient as other solutions. It's pretty logical to assume it'll be > In the early 1900s, gas was less efficient than electricity too I think you mean gasoline instead of just gas. Hydrogen requires huge amounts of energy before it's easy to transport, which is what you responded to. In any case, in the early 1900s, gasoline had a huge amount of stored energy. It was a matter of using it efficiently, you're comparing apples to oranges. With Green Hydrogren too often people say that some technological improvement will solve the drawbacks. While ignoring that for e.g. hydrogen it's not so easy, for other options it is/was. Same for the often suggested "solution" of using surplus energy. A factory that doesn't work 24/7 is more costly. Aside from that I understood that hydrogen is best produced continuously for it to be efficient.
- mustafa_pasi 3y ago
  >Efficiency has a huge impact on the cost/economics Not in the way that you think, no. For all intents and purposes, we have limitless energy. The problem was never that we don't have enough capacity, because we can scale capacity as much as we want. The only thing that is required is that energy generation (i.e. $/kWh) is cheap enough, and this seems feasible with solar and wind and maybe fission and later one fusion or other sources. >you're comparing apples to oranges You are the one saying, "just attach a transmission line to it" or "just put a battery in it", without thinking of all the cases where this is just not possible. Nobody is arguing that you should start powering your toaster with hydrogen. You all are attacking a strawman, it seems.
  - sitkack 3y ago
    You would have to solve the problem of getting soggy toast from the exhaust steam.
    - angiosperm 3y ago
      Unscheduled detonations would put an, er, damper on adoption.
      - sitkack 3y ago
        I believe that would be toast toast.
- someplaceguy 3y ago
  > Efficiency has a huge impact on the cost/economics It doesn't have nearly as much impact as other factors, such as abundance of the material, how easy/practical it is to work with it (which influences both demand and supply), whether mass infrastructure for it already exists (although this is more relevant in the short-term rather than long-term), etc. These factors impact the economics of an energy source much more than efficiency, and economics is by far the most important factor in deciding whether an energy source will be used or not (and how much of it), not efficiency. e.g. if hydrogen is only 10% efficient but there's 10 times more of it on Earth compared to a similar energy source that is 90% efficient, then hydrogen wins (all other factors being equal). As another example, if hydrogen tanks in cars explode 100 times as often as gas tanks, then it would probably be a complete non-starter for powering vehicles, regardless of efficiency.
mrpopo 3y ago
Not really, increasing energy efficiency is at the heart of many climate solutions. Clean energy is still scarce, and in the places where it isn't, for instance Germany, there is backlash against it. Not to mention that they aren't even close to being 100% renewable-powered (wind+solar 30%), not even close to have 100% EV market penetration (about 2%), not even close to have the theoretical capacity for a grid to power 100% EVs, and you would like to adopt a less efficient technology that would require to double the clean power needs compared to EVs...
- mustafa_pasi 3y ago
  Manufacturing a whole new vehicle with a huge ass battery that is more cost intensive to manufacturing than a comparable ICE, a vehicle that due to contemporary trends has to be a 5-ton lifted SUV, a vehicle that is going to be used by ONE person to commute to work along a fixed predetermined route, a vehicle that is going to be replaced after 3 years because this person have to have the newest four wheels on the lot to project status to attract a status obsessed mate, all that is ALSO EXTREMELY energy inefficient. If you truly cared about energy efficiency you'd proposition the ban or severe limitation of private car usage in sufficiency dense localities. Public trams and busses, cycling, walking, and maybe even very small private vehicles would be extremely more energy efficient. There is nothing about a 5-ton EV SUV that says energy efficiency.
  - _aavaa_ 3y ago
    That's a criticism of trends in automobiles (which I agree with) not something inherent to BEVs. Guess what, if you get a BEV with 1/3-1/4 the battery size, the range is smaller, but for most people it will be fine. And now your vehicle is not lugging around all that excess weight. And do you really need a massive electric pickup truck? It's absolutely possible, but I bet for most people it's a preference.
  - mrpopo 3y ago
    Obviously reducing private car usage is a priority. I don't have a car, never owned one, and I'm absolutely in favour of severe restrictions. Now, you have to acknowledge the world we live in, a total ban won't be feasible in the time-frame that we have to combat climate change. (And neither will an electric grid sufficiently powerful to power millions of green hydrogen-powered vehicles or 5-ton SUVs for that matter). Not all EVs weigh 5 tons. Promoting (smaller) EVs for people who need them is a good thing.
_aavaa_ 3y ago
Yes, gasoline won because it was more convenient. Hydrogen (and explosive gas which is notorious difficult to transport and work with safely) is neither efficient nor convenient.
kakwa_ 3y ago
Efficiency gains can even very well be detrimental to resource consumption. Efficiency gains generally lead to lower cost, which in turn lead to higher demand. And this increased demand can very well be in excess of the efficiency gain. This was observed as early as the 1860ies and theorized in concepts like the Jevons Paradox/Rebound Effect. This doesn't mean efficiency gains are not desirable, but they must be implemented in conjunction with other factors like environmental policies. https://en.wikipedia.org/wiki/Jevons_paradox https://en.wikipedia.org/wiki/Jevons_paradox https://en.wikipedia.org/wiki/Rebound_effect_(conservation) https://en.wikipedia.org/wiki/Rebound_effect_(conservation)
- _aavaa_ 3y ago
  It's true, but that isn't a given. For example, it won't matter how cheap and efficient LEDs are, people aren't going to keep adding them to their house.
  - kakwa_ 3y ago
    Indeed, this effect is not a given, specially if the resource is scarce to begin with. But regarding your example, personally, I'm actually kind of "keep adding light bulbs" thanks to LEDs. I'm no longer using one central 75W incandescent bulb per room, but rather 4 or 5 Philips Hue lights (bulbs & led strips) in an indirect fashion. Hue bulbs & these new usages would not have existed without the LED efficiency gains. This counter example, of course, has many flaws, firstly, it's only my specific situation, not an average case. The efficiency gains (energy and longevity) is only part of what enabled these new types of lights. And lastly, I think my energy consumption is still lower non-the-less. But it demonstrate how things might not be so clear cut.

hkt 3y ago

100% this. Few people have been able to answer the question of "how does it compare to a heat pump that has a SCOP of 4?" without me having to fight the urge to roll my eyes. By the time (highly explosive) hydrogen gets into people's homes I'd be surprised if it was even 20% as efficient as a heat pump.

wffurr 3y ago
You would use hydrogen to produce methane to then burn in people's existing as furnaces using the existing natural gas distribution infrastructure. That seems to be Terraform's plan. Still seems better to me to convert as much housing as possible to heat pumps, which seem much better fit for purpose than on-site combustion. I think green hydrogen has a lot more potential as a precursor to liquid fuels for e.g. aviation and shipping, which otherwise will be extremely difficult to electrify.
- _aavaa_ 3y ago
  If you're going to convert it into methane and burn it you'll make a fuel cell's ~37% round trip efficiency look massive. turning it into methane to burn it is trying to solve last century's problem. People need way to stay warm not things to burn.
  - wffurr 3y ago
    I think their point for syngas (or better yet synthetic liquid fuels) is that solar will be so cheap that the efficiency won't matter.
    - hkt 3y ago
      Except that efficiency really does matter right now as energy demands are increasing globally

aredox 3y ago

I concur: Hydrogen is a "bad" fuel in terms of practicality: it's extremely reactive and it leaks easily. To make a parallel with rocket science: there are extremely efficient liquid chemical propellants, much better than what is in use today, like Chlorine Trifluoride, that nobody uses anymore because they are just too dangerous to work with. Or the fact that hydrogen airships will never come back: nobody will ever, ever switch from helium despite the cost and lift difference. Hydrogen has its uses (e.g. steel plants). Transportation is not one of them.

arijun 3y ago
I was curious about Chlorine Trifluoride as a propellant, and I found this quote of John D Clark on the Wiki page (hypergolic means it will ignite spontaneously): > It is, of course, extremely toxic, but that's the least of the problem. It is hypergolic with every known fuel, and so rapidly hypergolic that no ignition delay has ever been measured. It is also hypergolic with such things as cloth, wood, and test engineers, not to mention asbestos, sand, and water—with which it reacts explosively. It can be kept in some of the ordinary structural metals—steel, copper, aluminum, etc.—because of the formation of a thin film of insoluble metal fluoride that protects the bulk of the metal, just as the invisible coat of oxide on aluminum keeps it from burning up in the atmosphere. If, however, this coat is melted or scrubbed off, and has no chance to reform, the operator is confronted with the problem of coping with a metal-fluorine fire. For dealing with this situation, I have always recommended a good pair of running shoes
- wffurr 3y ago
  Ignition! - a history of rocket fuels - from which this quote originates - is freely available online and an excellent read: https://library.sciencemadness.org/library/books/ignition.pdf https://library.sciencemadness.org/library/books/ignition.pd...
dabluecaboose 3y ago
>Hydrogen has its uses (e.g. steel plants). Transportation is not one of them. Small caveat, hydrogen is still pretty useful for upper stage rocket propulsion because of its low mass and high specific impulse.

rcme 3y ago

It actually doesn’t have to do with transmission at all. Rather, when you pay for electrolysis, you’re paying for all the energy inputs. When you burn fossil fuels, you’re not paying for any of the energy inputs (hundreds of millions of years of solar radiation). So it’s not surprising that fossil fuels are cheaper even if they’re less efficient.

_aavaa_ 3y ago
Firstly I don't see how that follows. You still need to pay to transport both the oil and the hydrogen from where you make it to where you use it. Most importantly, you're not (in most places) paying for the pollution of the atmosphere. E.g. Prices on carbon are nowhere near the level of societal harm that putting it into the atmosphere causes.
- rcme 3y ago
  My point is that to produce hydrogen via electrolysis, you need to input energy. Due to thermodynamics, you can only ever hope to get 0.9 units for each unit of input energy. With fossil fuels, you don’t need to input energy to get them. At least not in the same way. You can run a pump to pump them out of the ground. For each unit of energy that goes into the pump, you likely get 1000x units of energy out.
  - _aavaa_ 3y ago
    I get what you mean. That will really depend on where you get the oil from. Some places need a lot more downstream processing (looking at alberta oil sands) to get something useable than others (the middle east). Whether you want to consider that analogous to the electrolysis step or to another one is not clear since the processes don't map one to one.