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Liquid hydrogen or ammonia are both very much feasible and carbon-free. Both Yanmar and Kawasaki are developing large marine four-stroke piston engines for hyd

Liquid hydrogen or ammonia are both very much feasible and carbon-free. Both Yanmar and Kawasaki are developing large marine four-stroke piston engines for hydrogen, with 2025 as launch date. Ammonia-fuelled piston engines are easy, their only problem is idling due to the poor combustion properties of ammonia, which you can solve in the pragmatic way by using a little hydrocarbons during idle - combined with power from shore during docking, that still gets you >95% emission reductions.

MagnumOpus 3y ago
Hydrogen has the problem with thick-walled heavy fuel tanks - problematic for both cars and planes. Ammonia to my knowledge has a problem of both potential toxicity (both if gas escapes in refuelling and NOx emissions after burning) and needing enriched pure oxygen rather than running with atmospheric air. Propane or other hydrocarbons look superior to both of these to me.
- Qwertious 3y ago
  Hydrogen has problems, but at the end of the day it's viable and are the best option for planes/ships if we don't find anything better. On ships fairly easily, on planes with a fair bit of re-engineering. Local pollution aside, renewable hydrocarbons would be a better option, if they're viable at all.
  - Retric 3y ago
    Green hydrogen is still horrifically expensive, wind powered cargo ships are currently more valuable though not actually viable without a massive carbon tax. Batteries can provide enough power for ships electrical systems. There’s some niche fully battery powered boats which work fine for trips up to a few hundred miles. A full EV transition would also free up quite a lot of biofuels. Not enough on its own, but still significant.
    - Qwertious 3y ago
      Green hydrogen is expensive, yes, but less expensive than synthfuel. I'm not thrilled at the prospect of a green hydrogen future, but it's our best option for replacing fossil fuels currently, and so is what we should adopt if we can't come up with a better solution in the next 10-20 years. To my knowledge wind-powered cargo ships can only supplement cargo ships and can't fully substitute for a proper fuel source, but I would absolutely love to be proven wrong. The bulk of biofuels are a dead end (although some types of biofuels are valuable in recycling waste products), because modern agriculture basically just turns oil into food; BEV tractors basically don't work due to the range and charging-times needed on an already very heavy vehicle.
      - Retric 3y ago
        BEV tractors work fine with hot swapping batteries. It’s not perfect in every single way, but there are significant benefits to offset the downsides. EX: “Monarch also offers a battery swap cart to keep the tractor running and uses 90% fewer moving parts than a comparable diesel unit. ” https://www.agweb.com/news/machinery/new-machinery/future-electric-farm-equipment https://www.agweb.com/news/machinery/new-machinery/future-el... I don’t think green hydrogen or synthetic fuel is a realistic option yet. As to a fully wind powered boats, the last fully wind powered cargo boat used commercially lasted until the 1960’s it lost but not by some huge margin. So yes fossil fuels win, but they don’t win by such a huge margin that a fuel costing 4x as much also wins. Hybrid battery/solar + wind boats are still a common thing for houseboats and pleasure craft in part because of the cost advantages. At even a 2x cost bump over bunker fuel I suspect bulk shipping would start to go a similar route. Militaries and billionaire super yachts might go with hydrogen or synthetic fuel’s it just a question of how quickly their prices fall.
        _hypx 3y ago
        I don't think you fully grasp the sheer inability of batteries to power a cargo ship. It is something like 50x too low energy density to work. Even with wind power, it is still far from being able to pull this off. Not to mention cost: The batteries will be many times more expensive than the ship itself. The whole idea is totally DOA. It is going to be some kind of chemical fuel, it is just a question of what and when. The alternative is just people not doing their physics homework and being totally wrong.
  - walnutclosefarm 3y ago
    If the efficiency of propane production (from atmospheric CO2) can be made even close to that for hydrogen from hydrolysis, then the systems benefits of propane over compressed and/or liquid hydrogen will blow liquid hydrogen out of the water. Hydrogen is an awful fuel. It's only real advantage is the potential for being carbon neutral, and the fact that it doesn't create noxious air pollution when used in a fuel cell. It's claimed advantage of energy density is at best a wash in most applications - higher density by mass, but much lower by volume. But everything to do with hydrogen as a fuel system is hard, complicated, and expensive, compared to the alternatives.
    - Qwertious 3y ago
      What's your point? I literally said "renewable hydrocarbons will be a better alternative". I'm saying that hydrogen is a bad option, but if e.g. this renewable propane turns out to cost $1000/litre then hydrogen wins by default. It wouldn't be that surprising, current synthfuel is expensive AF. And this new headline hasn't been commercialized yet, so it might not be viable after all. The benefit of hydrogen fuel is that, while it works poorly, it does work and is already in use today, in e.g. forklifts. It was in use decades ago, in fact. It's boring and low-risk, if we can't find anything good.
  - SoftTalker 3y ago
    Storing propane is much easier than storing hydrogen. It liquifes at reasonable pressure so it can be stored as a liquid in uninsulated, relatively lightweight tanks (the tank under your BBQ grill is an example). Hydrogen leaks out of almost everything, embrittles steel, is hard to store as a liquid and needs very high pressures to store a meaningful amount as a gas.
    - Qwertious 3y ago
      Renewable propane would be great, better than hydrogen fuel, but it doesn't exist yet. It might never pan out.
bawolff 3y ago
If the carbo is being extracted from the atmosphere, does it really matter it gets rereleased? It would still be net-zero.
- rocqua 3y ago
  Might be better of extracting the carbon and just storing it, rather than releasing it again. Net-zero is nice, but extraction and storage is net-negative.
- regularfry 3y ago
  By the time any of this hits a reasonable scale we'll be past a reasonable CO2 level in the atmosphere. The best thing to do may well be to use it as plastic feedstock and just chuck it into landfill.
Slava_Propanei 3y ago
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MagnumOpus 3y ago

Hydrogen has the problem with thick-walled heavy fuel tanks - problematic for both cars and planes. Ammonia to my knowledge has a problem of both potential toxicity (both if gas escapes in refuelling and NOx emissions after burning) and needing enriched pure oxygen rather than running with atmospheric air. Propane or other hydrocarbons look superior to both of these to me.

Qwertious 3y ago
Hydrogen has problems, but at the end of the day it's viable and are the best option for planes/ships if we don't find anything better. On ships fairly easily, on planes with a fair bit of re-engineering. Local pollution aside, renewable hydrocarbons would be a better option, if they're viable at all.
- Retric 3y ago
  Green hydrogen is still horrifically expensive, wind powered cargo ships are currently more valuable though not actually viable without a massive carbon tax. Batteries can provide enough power for ships electrical systems. There’s some niche fully battery powered boats which work fine for trips up to a few hundred miles. A full EV transition would also free up quite a lot of biofuels. Not enough on its own, but still significant.
  - Qwertious 3y ago
    Green hydrogen is expensive, yes, but less expensive than synthfuel. I'm not thrilled at the prospect of a green hydrogen future, but it's our best option for replacing fossil fuels currently, and so is what we should adopt if we can't come up with a better solution in the next 10-20 years. To my knowledge wind-powered cargo ships can only supplement cargo ships and can't fully substitute for a proper fuel source, but I would absolutely love to be proven wrong. The bulk of biofuels are a dead end (although some types of biofuels are valuable in recycling waste products), because modern agriculture basically just turns oil into food; BEV tractors basically don't work due to the range and charging-times needed on an already very heavy vehicle.
    - Retric 3y ago
      BEV tractors work fine with hot swapping batteries. It’s not perfect in every single way, but there are significant benefits to offset the downsides. EX: “Monarch also offers a battery swap cart to keep the tractor running and uses 90% fewer moving parts than a comparable diesel unit. ” https://www.agweb.com/news/machinery/new-machinery/future-electric-farm-equipment https://www.agweb.com/news/machinery/new-machinery/future-el... I don’t think green hydrogen or synthetic fuel is a realistic option yet. As to a fully wind powered boats, the last fully wind powered cargo boat used commercially lasted until the 1960’s it lost but not by some huge margin. So yes fossil fuels win, but they don’t win by such a huge margin that a fuel costing 4x as much also wins. Hybrid battery/solar + wind boats are still a common thing for houseboats and pleasure craft in part because of the cost advantages. At even a 2x cost bump over bunker fuel I suspect bulk shipping would start to go a similar route. Militaries and billionaire super yachts might go with hydrogen or synthetic fuel’s it just a question of how quickly their prices fall.
      - _hypx 3y ago
        I don't think you fully grasp the sheer inability of batteries to power a cargo ship. It is something like 50x too low energy density to work. Even with wind power, it is still far from being able to pull this off. Not to mention cost: The batteries will be many times more expensive than the ship itself. The whole idea is totally DOA. It is going to be some kind of chemical fuel, it is just a question of what and when. The alternative is just people not doing their physics homework and being totally wrong.
- walnutclosefarm 3y ago
  If the efficiency of propane production (from atmospheric CO2) can be made even close to that for hydrogen from hydrolysis, then the systems benefits of propane over compressed and/or liquid hydrogen will blow liquid hydrogen out of the water. Hydrogen is an awful fuel. It's only real advantage is the potential for being carbon neutral, and the fact that it doesn't create noxious air pollution when used in a fuel cell. It's claimed advantage of energy density is at best a wash in most applications - higher density by mass, but much lower by volume. But everything to do with hydrogen as a fuel system is hard, complicated, and expensive, compared to the alternatives.
  - Qwertious 3y ago
    What's your point? I literally said "renewable hydrocarbons will be a better alternative". I'm saying that hydrogen is a bad option, but if e.g. this renewable propane turns out to cost $1000/litre then hydrogen wins by default. It wouldn't be that surprising, current synthfuel is expensive AF. And this new headline hasn't been commercialized yet, so it might not be viable after all. The benefit of hydrogen fuel is that, while it works poorly, it does work and is already in use today, in e.g. forklifts. It was in use decades ago, in fact. It's boring and low-risk, if we can't find anything good.
- SoftTalker 3y ago
  Storing propane is much easier than storing hydrogen. It liquifes at reasonable pressure so it can be stored as a liquid in uninsulated, relatively lightweight tanks (the tank under your BBQ grill is an example). Hydrogen leaks out of almost everything, embrittles steel, is hard to store as a liquid and needs very high pressures to store a meaningful amount as a gas.
  - Qwertious 3y ago
    Renewable propane would be great, better than hydrogen fuel, but it doesn't exist yet. It might never pan out.

bawolff 3y ago

If the carbo is being extracted from the atmosphere, does it really matter it gets rereleased? It would still be net-zero.

rocqua 3y ago
Might be better of extracting the carbon and just storing it, rather than releasing it again. Net-zero is nice, but extraction and storage is net-negative.
regularfry 3y ago
By the time any of this hits a reasonable scale we'll be past a reasonable CO2 level in the atmosphere. The best thing to do may well be to use it as plastic feedstock and just chuck it into landfill.

Slava_Propanei 3y ago

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