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These are backwards looking arguments. I'm talking about a future where: fuel cell cars are far cheaper, hydrogen is approximately as cheap and efficient as ele

by Hypx 6y ago

These are backwards looking arguments. I'm talking about a future where: fuel cell cars are far cheaper, hydrogen is approximately as cheap and efficient as electricity, there is a substantial hydrogen infrastructure in place, and range is 400 miles or more (this has already happened). BTW the last statement was always wrong as modern fuel cell vehicles are more reliable than battery powered ones. It will be green hydrogen too. I don't think anyone is seriously proposing grey hydrogen as a fuel.

bryanlarsen 6y ago
> hydrogen is approximately as cheap and efficient as electricity This is physically impossible. Green hydrogen is created from electricity and water and is converted back to electricity and water in a fuel cell. These are both lossy processes.
- Hypx 6y ago
  No more so than a battery. A fuel cell is in fact a battery of sorts, and it's not out of the question that it approaches the efficiency of a conventional battery. It should also be pointed out that the lower weight of a fuel cell powertrain allows you to use less energy during operation. So even if fuel cells don't fully match the efficiency of conventional batteries, they can still use less energy on a final basis.
  - bryanlarsen 6y ago
    Measuring power loss between electricity generation and wheels, current fuel cell cars are 25-35% efficient. Teslas are 90% efficient. (https://www.greencarreports.com/news/1127660_battery-electric-or-hydrogen-fuel-cell-vw-lays-out-why-one-is-the-winner https://www.greencarreports.com/news/1127660_battery-electri...) A Toyota Mirai weighs 1848kg. A Tesla Model 3 weighs 1612kg.
    - Hypx 6y ago
      It's probably closer to 40% and 75% respectively. VW is probably not being totally honest with their numbers. This gap will shrink in the future. The Mirai is overbuilt for what it is. The Hyundai Nexo is 1814-1873 kg despite being an SUV. For reference, the Model Y is 2003 kg.
      - bryanlarsen 6y ago
        The single motor standard range version of the Y would be about 200 kg lighter, and is a bigger vehicle than the Nexo. The motors in the Model 3 are 97% efficient. 90% for the entire system is not a dishonest number
        Hypx 6y ago
        On the other hand, the Nexo is storing a much larger amount of energy. At 6.3 kg of hydrogen and at 33.3 kWh of usable energy per kg, that's 209.8 kWh. The Y only stores 75 kWh in comparison. Fuel cells are around 60% efficient today. The system efficiency is probably around 55%. This is a number that will increase as fuel cells get more efficient. I believe the gap will eventually close altogether, or at least shrink greatly.
- rsfern 6y ago
  I think your focus is a bit narrow here, and physical impossibility is a really strong statement. Advances in photocatalytic water splitting could easily make this a reality. That said I’m under the impression that progress in battery tech is a lot more active right now, and it’s not really clear that finding an efficient and economical photocatalytic material is very realistic
  - bryanlarsen 6y ago
    No matter how efficient your hydrogen production is, it still has to be compressed and chilled. You can't do this without energy.
    - rsfern 6y ago
      Sure, I agree with you, it seems unlikely that fuel cell tech will overtake advances in batteries in the near future, and that compressed hydrogen doesn’t seem likely to become competitive. My point is that there are many other hydrogen generation and storage technologies at various degrees of maturity and viability, and it doesn’t seem productive to write off a potential economical fuel cell system as a physical impossibility. I do think there are many challenging engineering problems along that path, and I’m not convinced it’s tractable at all, much less likely to outpace advances in battery systems.
      - Hypx 6y ago
        > I do think there are many challenging engineering problems along that path, and I’m not convinced it’s tractable at all, much less likely to outpace advances in battery systems. I disagree on that last part. Fuel cell is moving at warp speed right now, and batteries are losing ground at a rapid rate. We're seeing fuel cells move into everything from e-bikes to aircraft. If there's any kind of disruptive event here, it will be fuel cells replacing batteries at a much faster rate than expected.
    - Hypx 6y ago
      Not necessarily. You can store it in metal hydrides. It's also a small amount of energy comparatively, so it's not a big loss. Finally, you can recover a lot of the energy back.
ericb 6y ago
We already have electrical transport infrastructure everywhere to the last mile. Hydrogen, not so much.

by Hypx 6y ago

bryanlarsen 6y ago

> hydrogen is approximately as cheap and efficient as electricity This is physically impossible. Green hydrogen is created from electricity and water and is converted back to electricity and water in a fuel cell. These are both lossy processes.

Hypx 6y ago
No more so than a battery. A fuel cell is in fact a battery of sorts, and it's not out of the question that it approaches the efficiency of a conventional battery. It should also be pointed out that the lower weight of a fuel cell powertrain allows you to use less energy during operation. So even if fuel cells don't fully match the efficiency of conventional batteries, they can still use less energy on a final basis.
- bryanlarsen 6y ago
  Measuring power loss between electricity generation and wheels, current fuel cell cars are 25-35% efficient. Teslas are 90% efficient. (https://www.greencarreports.com/news/1127660_battery-electric-or-hydrogen-fuel-cell-vw-lays-out-why-one-is-the-winner https://www.greencarreports.com/news/1127660_battery-electri...) A Toyota Mirai weighs 1848kg. A Tesla Model 3 weighs 1612kg.
  - Hypx 6y ago
    It's probably closer to 40% and 75% respectively. VW is probably not being totally honest with their numbers. This gap will shrink in the future. The Mirai is overbuilt for what it is. The Hyundai Nexo is 1814-1873 kg despite being an SUV. For reference, the Model Y is 2003 kg.
    - bryanlarsen 6y ago
      The single motor standard range version of the Y would be about 200 kg lighter, and is a bigger vehicle than the Nexo. The motors in the Model 3 are 97% efficient. 90% for the entire system is not a dishonest number
      - Hypx 6y ago
        On the other hand, the Nexo is storing a much larger amount of energy. At 6.3 kg of hydrogen and at 33.3 kWh of usable energy per kg, that's 209.8 kWh. The Y only stores 75 kWh in comparison. Fuel cells are around 60% efficient today. The system efficiency is probably around 55%. This is a number that will increase as fuel cells get more efficient. I believe the gap will eventually close altogether, or at least shrink greatly.
rsfern 6y ago
I think your focus is a bit narrow here, and physical impossibility is a really strong statement. Advances in photocatalytic water splitting could easily make this a reality. That said I’m under the impression that progress in battery tech is a lot more active right now, and it’s not really clear that finding an efficient and economical photocatalytic material is very realistic
- bryanlarsen 6y ago
  No matter how efficient your hydrogen production is, it still has to be compressed and chilled. You can't do this without energy.
  - rsfern 6y ago
    Sure, I agree with you, it seems unlikely that fuel cell tech will overtake advances in batteries in the near future, and that compressed hydrogen doesn’t seem likely to become competitive. My point is that there are many other hydrogen generation and storage technologies at various degrees of maturity and viability, and it doesn’t seem productive to write off a potential economical fuel cell system as a physical impossibility. I do think there are many challenging engineering problems along that path, and I’m not convinced it’s tractable at all, much less likely to outpace advances in battery systems.
    - Hypx 6y ago
      > I do think there are many challenging engineering problems along that path, and I’m not convinced it’s tractable at all, much less likely to outpace advances in battery systems. I disagree on that last part. Fuel cell is moving at warp speed right now, and batteries are losing ground at a rapid rate. We're seeing fuel cells move into everything from e-bikes to aircraft. If there's any kind of disruptive event here, it will be fuel cells replacing batteries at a much faster rate than expected.
  - Hypx 6y ago
    Not necessarily. You can store it in metal hydrides. It's also a small amount of energy comparatively, so it's not a big loss. Finally, you can recover a lot of the energy back.

ericb 6y ago

We already have electrical transport infrastructure everywhere to the last mile. Hydrogen, not so much.