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Green hydrogen as a road transport fuel probably doesn't make sense at all, nevermind burning it at ~25% efficiency. Fuel cells are a possibility at ~90% effici

Green hydrogen as a road transport fuel probably doesn't make sense at all, nevermind burning it at ~25% efficiency. Fuel cells are a possibility at ~90% efficiency but there are so many industrial used of hydrogen that we'd be better displacing methane derived hydrogen in those places before considering it for transport.

sandworm101 4y ago
I'm not so sure. Some of the diesel-from-air tech looks promising. It is expensive, more expensive than reasonable battery tech at the moment, but I wouldn't abandon the concept. If BMW wants to research and potentially sell a zero-carbon combustion fuel cycle, more power to them.
- avianlyric 4y ago
  I’m not sure how such technology can ever be cheaper than EVs. Creating the fuel requires energy, the best supply of high volume, high quality CO2 neutral energy is electricity derived from carbon neutral sources (solar, wind, tidal, etc). Why would you take perfectly good electricity, use it to create a synthetic liquid fuel using a lossy process (some energy will be lost as heat), then burn that fuel to extract, at most, 25% of the energy you used to create the fuel. Rather than just taking the electricity, putting it in a battery, and running an electric motor. A process that’s 70%-90% efficient. The cost difference between EVs and ICE cars would have to be astronomical to make synthetic fuel ICE cars appealing when compared to EVs. There still a use case for synthetic fuels, but that only in situations where you already have a large ICE fleet (could be cars, trucks, ships, planes) that are very expensive to replace, or where batteries don’t mix well with the form of transport (aircraft for example). But for _new_ passenger vehicles, where EVs are basically a solved problem, I can’t see how a new ICE + synthetics fuel could possibly hope to compete with a new EV + electricity.
  - sandworm101 4y ago
    Total lifecycle. An ic can be made out of 99% easily recyclable metals. Lithium battery tech currently remains very tricky to recycle.
    - bryanlarsen 4y ago
      An ICE uses ~50 tons of gasoline over its lifetime that have to be included in total lifecycle calculations. That gasoline isn't easy to recycle. OTOH, Lithium is easy to recycle, and a car only uses ~50kg of it.
  - 7952 4y ago
    Car manufacturers have made an artform out of selling questionable tradeoffs to customers. It doesn't need to be technically perfect (like an SUV). It just needs to sell.
    - avianlyric 4y ago
      It not a question of technically perfect or otherwise. It’s just a pure question of cost. When one approach is half as efficient as the other, it hard to see how you build a cost competitive product using the less efficient approach. Especially when the more efficient approach is already approaching price parity, with a much cheaper technology (diesel from the ground is much cheaper than diesel from the air).
- deleted 4y ago
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sandworm101 4y ago

I'm not so sure. Some of the diesel-from-air tech looks promising. It is expensive, more expensive than reasonable battery tech at the moment, but I wouldn't abandon the concept. If BMW wants to research and potentially sell a zero-carbon combustion fuel cycle, more power to them.

avianlyric 4y ago
I’m not sure how such technology can ever be cheaper than EVs. Creating the fuel requires energy, the best supply of high volume, high quality CO2 neutral energy is electricity derived from carbon neutral sources (solar, wind, tidal, etc). Why would you take perfectly good electricity, use it to create a synthetic liquid fuel using a lossy process (some energy will be lost as heat), then burn that fuel to extract, at most, 25% of the energy you used to create the fuel. Rather than just taking the electricity, putting it in a battery, and running an electric motor. A process that’s 70%-90% efficient. The cost difference between EVs and ICE cars would have to be astronomical to make synthetic fuel ICE cars appealing when compared to EVs. There still a use case for synthetic fuels, but that only in situations where you already have a large ICE fleet (could be cars, trucks, ships, planes) that are very expensive to replace, or where batteries don’t mix well with the form of transport (aircraft for example). But for _new_ passenger vehicles, where EVs are basically a solved problem, I can’t see how a new ICE + synthetics fuel could possibly hope to compete with a new EV + electricity.
- sandworm101 4y ago
  Total lifecycle. An ic can be made out of 99% easily recyclable metals. Lithium battery tech currently remains very tricky to recycle.
  - bryanlarsen 4y ago
    An ICE uses ~50 tons of gasoline over its lifetime that have to be included in total lifecycle calculations. That gasoline isn't easy to recycle. OTOH, Lithium is easy to recycle, and a car only uses ~50kg of it.
- 7952 4y ago
  Car manufacturers have made an artform out of selling questionable tradeoffs to customers. It doesn't need to be technically perfect (like an SUV). It just needs to sell.
  - avianlyric 4y ago
    It not a question of technically perfect or otherwise. It’s just a pure question of cost. When one approach is half as efficient as the other, it hard to see how you build a cost competitive product using the less efficient approach. Especially when the more efficient approach is already approaching price parity, with a much cheaper technology (diesel from the ground is much cheaper than diesel from the air).
deleted 4y ago
[deleted]