3 ms·

Where's the difference that makes it feasible for powering the grid, but not for powering vehicles?

JumpCrisscross 4y ago
> Where's the difference that makes it feasible for powering the grid, but not for powering vehicles? Energy density. For the fuel alone, volumetrically. Altogether, massively as well.
- whatwherewhy 4y ago
  Isn't H2 energy density much better than Li-Ion batteries? I don't understand why it's not applicable to transport if so.
  - JumpCrisscross 4y ago
    > Isn't H2 energy density much better than Li-Ion batteries? By weight, hydrogen and oxygen creates 20x more chemical energy per kilogram than lithium-ion batteries [1]. (It's comparable to gasoline and air.) By volume, uncompressed, it has far less. Once compressed, we have to take into account the weight of the containment tanks, the weight of the fuel cell and the energy lost in converting hydrogen to electricity, an output batteries directly provide, a combination which negates that specific energy advantage. [1] https://en.wikipedia.org/wiki/Energy_density_Extended_Reference_Table https://en.wikipedia.org/wiki/Energy_density_Extended_Refere...
  - rgmerk 4y ago
    H2 energy density is better than Li-Ion batteries, particularly by weight, but: * Hydrogen is very light but takes up quite a lot of volume so it needs to be either liquified or compressed to very high pressures (and even then it's considerably bulkier than, say, natural gas). * The resulting storage tanks are heavy and add bulk. * The fuel cell to convert the hydrogen to electricity adds weight that a battery system doesn't have (the storage is the converter). * The energy density of lithium-ion batteries doesn't have to match hydrogen or gasoline, it just has to be good enough. For most light vehicle applications, we're getting pretty close to that point (though possibly not if you're planning to use a truck to tow things). For heavy transport, the balance changes because big tanks are more mass-efficient than smaller ones, and the sheer mass of batteries currently required for long-haul trucking seriously cuts into the cargo that can be legally carried with road mass limits. That's why there's interest in hydrogen-fuelled trucks. For hydrogen-fuelled planes, a similar argument applies with current and reasonably foreseeable battery technology you can't build an airliner with a useful carrying capacity and range. However, the bulk of hydrogen tanks required for a plane with intercontinental range is still a big problem. That's why you see all these unconventional body design concepts for hydrogen-fuelled planes - you need lots of room to store the hydrogen and still give a useful passenger load.
rapsey 4y ago
Cars require a large infrastructure to be in place. EVs use the power grid. Much faster and cost efficient to build large Solar+hydrogen power plants and drive EVs.
danielheath 4y ago
To power vehicles, you would need fuel stations all around the country with hydrogen-fuel equipment. To power the grid from excess solar, you need a hydrogen-burning generator at the site of the electrolysis plant.
- bamboozled 4y ago
  To power vehicles, you would need fuel stations all around the country with hydrogen-fuel equipment. Why does this keep coming up? Who cares about this specific point? If there is demand, people will build the fuel stations, like we did with gas and oil? I get there are other harder problems with Hydrogen, but worrying about infrastructure seems strange?
  - AtlasBarfed 4y ago
    To summarize, IF you get the practical engineering resolved, IF you get all the consumer products designed and ready for manufacturing, and IF you get a de minimis infrastructure to scale from, that's ... 15 years? Hydrogen infrastructure, if what we're talking about is on the scale of current ICE cars, can't "organically" compete, and won't "organically" develop. It has no chance without a massive government investment/buy-in on a decade long scale. It needs huge investment for each of the big IFs I outlined above. Look at the cost curves of solar / wind / batteries for the last 10 years, and consider that there are numerous technologies about to be rolled out that will improve those at the same or better rate and the overall industrial scaleout / economies of scale isn't close to being done. Hydrogen is marketed these days with "hey it will cost X and that is (theoretically / lies damn lies and accounting) competitive with wind/solar/batteries (which exist and we KNOW what they cost) price today. But there is absolutely no chance of hydrogen being cost competitive in general power transmission/carrier, transportation, etc in 10-15 years. Heck in 5 years it likely won't. So the hydrogen people are praying that their lobbying + fortune would produce some boondoggle subsidy to build this out, and then the government would limp it along due to the sunk cost fallacy.

> Where's the difference that makes it feasible for powering the grid, but not for powering vehicles? Energy density. For the fuel alone, volumetrically. Altogether, massively as well.

whatwherewhy 4y ago
Isn't H2 energy density much better than Li-Ion batteries? I don't understand why it's not applicable to transport if so.
- JumpCrisscross 4y ago
  > Isn't H2 energy density much better than Li-Ion batteries? By weight, hydrogen and oxygen creates 20x more chemical energy per kilogram than lithium-ion batteries [1]. (It's comparable to gasoline and air.) By volume, uncompressed, it has far less. Once compressed, we have to take into account the weight of the containment tanks, the weight of the fuel cell and the energy lost in converting hydrogen to electricity, an output batteries directly provide, a combination which negates that specific energy advantage. [1] https://en.wikipedia.org/wiki/Energy_density_Extended_Reference_Table https://en.wikipedia.org/wiki/Energy_density_Extended_Refere...
- rgmerk 4y ago
  H2 energy density is better than Li-Ion batteries, particularly by weight, but: * Hydrogen is very light but takes up quite a lot of volume so it needs to be either liquified or compressed to very high pressures (and even then it's considerably bulkier than, say, natural gas). * The resulting storage tanks are heavy and add bulk. * The fuel cell to convert the hydrogen to electricity adds weight that a battery system doesn't have (the storage is the converter). * The energy density of lithium-ion batteries doesn't have to match hydrogen or gasoline, it just has to be good enough. For most light vehicle applications, we're getting pretty close to that point (though possibly not if you're planning to use a truck to tow things). For heavy transport, the balance changes because big tanks are more mass-efficient than smaller ones, and the sheer mass of batteries currently required for long-haul trucking seriously cuts into the cargo that can be legally carried with road mass limits. That's why there's interest in hydrogen-fuelled trucks. For hydrogen-fuelled planes, a similar argument applies with current and reasonably foreseeable battery technology you can't build an airliner with a useful carrying capacity and range. However, the bulk of hydrogen tanks required for a plane with intercontinental range is still a big problem. That's why you see all these unconventional body design concepts for hydrogen-fuelled planes - you need lots of room to store the hydrogen and still give a useful passenger load.

rapsey 4y ago

Cars require a large infrastructure to be in place. EVs use the power grid. Much faster and cost efficient to build large Solar+hydrogen power plants and drive EVs.

danielheath 4y ago

To power vehicles, you would need fuel stations all around the country with hydrogen-fuel equipment. To power the grid from excess solar, you need a hydrogen-burning generator at the site of the electrolysis plant.

bamboozled 4y ago
To power vehicles, you would need fuel stations all around the country with hydrogen-fuel equipment. Why does this keep coming up? Who cares about this specific point? If there is demand, people will build the fuel stations, like we did with gas and oil? I get there are other harder problems with Hydrogen, but worrying about infrastructure seems strange?
- AtlasBarfed 4y ago
  To summarize, IF you get the practical engineering resolved, IF you get all the consumer products designed and ready for manufacturing, and IF you get a de minimis infrastructure to scale from, that's ... 15 years? Hydrogen infrastructure, if what we're talking about is on the scale of current ICE cars, can't "organically" compete, and won't "organically" develop. It has no chance without a massive government investment/buy-in on a decade long scale. It needs huge investment for each of the big IFs I outlined above. Look at the cost curves of solar / wind / batteries for the last 10 years, and consider that there are numerous technologies about to be rolled out that will improve those at the same or better rate and the overall industrial scaleout / economies of scale isn't close to being done. Hydrogen is marketed these days with "hey it will cost X and that is (theoretically / lies damn lies and accounting) competitive with wind/solar/batteries (which exist and we KNOW what they cost) price today. But there is absolutely no chance of hydrogen being cost competitive in general power transmission/carrier, transportation, etc in 10-15 years. Heck in 5 years it likely won't. So the hydrogen people are praying that their lobbying + fortune would produce some boondoggle subsidy to build this out, and then the government would limp it along due to the sunk cost fallacy.