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It makes sense for large vehicles - a passenger plane from New York to London will never make sense for batteries, but could be done with hydrogen. Similarly,
by Qwertious 3y ago
It makes sense for large vehicles - a passenger plane from New York to London will never make sense for batteries, but could be done with hydrogen.
Similarly, cargo ships can't run on batteries, but could fairly trivially be switched to hydrogen with only minor loss in storage capacity (1-5%).
The benefit of hydrogen is that it was functioning just fine in the 1960s, there aren't any outright technical showstoppers here; just financial problems and technical problems that are hard to solve cheaply.
I'm not saying that hydrogen is the best solution (if synthfuel pans out then it'll be a perfect drop-in replacement for existing jet fuel), but it's a solution that exists today. It's there if we care.
Obviously we don't care, since coal plants are still around, but if we genuinely wanted to stop using fossil fuels ASAP then it would permit us to keep using planes/cargo ships.
- martincmartin 3y agoCouldn't cargo ships use wind? A wind turbine on the ship? A kind of modern re-imaging of how sailing ships of old were powered. Is the problem that wind isn't reliable and you might go days without it? Or you wouldn't fit in ports or other areas with a big turbine sticking out? Or is there some other practical problem.
- jackmott42 3y agoCargo ships could use wind sure, it would just be much slower and each boat would have to carry far less stuff. Might solve problems for countries that have lost their own manufacturing capacity because shipping products gets way less appealing.
- Manuel_D 3y agoIt's not just that wind is unreliable, it's also very low energy density. You'd need a lot of sails to haul a small amount of cargo. There are applications using kite sails to supplement combustion engines, but that's just an opportunistic mitigation.
- _aavaa_ 3y agoSeveral designs have been proposed for adding sails, of one shape or another, to ships in addition to an active mode of propulsion in order to reduce fuel consumption. Further, the ships take a significant amount of energy to get going, so much of that initial acceleration could be handled by strong tug boats which would then be immediately recharged.
- jackmott42 3y agoHow would a hydrogen powered passenger plane work? How big and or heavy would the fuel tanks need to be? As I understand it you either need very big tanks to store it as gas, or very heavy insulated tanks to store it liquefied. Would a passenger plane still work?
- _hypx 3y agoHydrogen planes have been tested. The physics works out provided you have more room for the tanks.
- _aavaa_ 3y agoAh yes, it works if only it weren’t for those pesky economic considerations. Making more room for the tanks means either less cabin/storage and/or bigger cross-section and increased drag.
- _hypx 3y agoThe alternative is SAF, which has to be a synthetic fuel if the goal is to be honestly green. However, that requires enormous green hydrogen production anyways.
- _aavaa_ 3y agoThe alternative is electric and biofuels.
- _hypx 3y agoThere will never be a long-distance battery powered plane. Not with any kind of battery we can conceive of today at any rate. And again, biofuels are not green.
- _aavaa_ 3y ago> There will never be a long-distance battery powered plane. "Long-distance" is a subjective term. There is an ever-increasing distance for which batteries are doable. Everything else is will be liquid biofuels, rather than efuels. Biofuels are as green as the process making them. Electrify the equipment being used (something that's being done for reasons orthogonal to this) and you're already made the process more green.
- pjc50 3y agoSynthfuel apparently exists already and the US Navy has a solution. It's just very energy-intensive. The shipping industry is investigating making ammonia from the hydrogen and then using that in fuel cells; it has the advantage that it's easier to handle. https://maritime-executive.com/article/highest-power-output-demonstrated-from-direct-ammonia-fuel-cell https://maritime-executive.com/article/highest-power-output-...
- HPsquared 3y agoThe Germans in WW2 made large quantities of synthetic fuel. It's not new, the same challenges continue to exist. Most of their military aviation fuel was apparently synthetic due to oil shortages. https://en.m.wikipedia.org/wiki/Synthetic_fuel#History https://en.m.wikipedia.org/wiki/Synthetic_fuel#History
- FreshStart 3y agoThe whole idiotic war would have been over the moment the free trade system of the US would have surplanted the pre-existing empires and their embargoes. Harber+Bosch + liquid gas is what feeds the world and creates the pre-requisite to all peace.
- getwiththeprog 3y agoLiquid gas may feed some of the world, but there are many left out with this centralized system. I am glad that decentralised electrical from solar and wind can fully replace the old system and look foward to a new many-noded culture which can allow all humanity to flourish.
- pjc50 3y ago> the free trade system of the US would have surplanted the pre-existing empires and their embargoes This doesn't make any sense: free trade is not a magic spell against the desires of imperialism, and the US embargoed Japan slightly before Japan attacked the US (but long into Japan's war with China).
- _hypx 3y agoIt will make sense for nearly all transportation that can’t be directly electrified. The problem with batteries is that it is a massive resource hog, and one that is fundamentally unsustainable. It will have be abandoned. The only alternatives are ideas like synfuels or ammonia, but those require green hydrogen production anyways.
- _aavaa_ 3y agoThey are not the only alternative. Ammonia (a toxic gas) as a fuel is an insane idea and will lead to needless deaths. Efuels are incredibly inefficient. Hard to justify paying 10x the price. Ammonia or synfuels are not the only alternative. The elephant in the room, the one fuel that is being used today is biofuel.
- _hypx 3y agoBiofuels are not green. It is purely greenwashing since the production of biofuels is very carbon intensive. It is also very environmentally destructive since it takes a lot of farmland to produce.
- _aavaa_ 3y agohttps://en.wikipedia.org/wiki/Cellulosic_ethanol https://en.wikipedia.org/wiki/Cellulosic_ethanol
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- moomoo11 3y agoThe best solution for large airplanes is remote meetings and realistic remote experiences. Sorry. But there’s no reason so many people need to fly (consultants, I used to be one racked up a few hundred thousand miles) besides leisure or critical travel. And it should reflect in the price so tickets aren’t $150 to be crammed in like cattle. And yes it should be rare to fly until we figure out cleaner fuel methods. Just my hot take.
- epistasis 3y agoLiquid hydrogen takes 4x the volume of standard aviation kerosene. Coming up with on-jet liquid storage of hydrogen of that volume is a rather steep engineering hurdle. And hydrogen, liquid or not, will require some rather impressive storage and handling techniques at the airport. If I were to bet, I would say that converting hydrogen to kerosene will be far cheaper and more efficient than trying to power long distance flight with hydrogen
- regularfry 3y agoThe problem isn't doing one plane. It's doing enough of them to make a difference. Jet fuel is ludicrously energy dense, to the extent that it's easy to underestimate how much energy you need: at any reasonably-sized airport, if you want to replace the current fleet then you need to be talking about roughly a power station's worth of continuous energy delivery into aircraft fuel tanks. That's doable with jet fuel because you're not climbing out of an energy well just to get hold of the fuel. You just separate it out, and the problem becomes pure logistics. With H2, the volume you need and the added storage complexity means the current logistics becomes a rounding error in comparison to how on earth you get the gigawatts to churn feedstock into gas. You could do it, but you'd want nukes on-site to do it.
- gumby 3y ago> ...there aren't any outright technical showstoppers here H2 molecules are extremely small -- storing them without loss is heavy and volumetrically expensive, making it implausible for any aircraft. The same factors apply to ships, pipelines etc because space for fuel is space that does not contain high value cargo.
- slushh 3y ago>The same factors apply to ships Ships don't care about weight. The cooling infrastructure or heavy steel tanks are possible.
- gumby 3y ago> Ships don't care about weight. The cooling infrastructure or heavy steel tanks are possible. Have you looked at how high the containers are stacked on a container ship? Space taken up by fuel is space that can't be sold. Source: we partner with commercial shipping companies and spend time not just talking to the commercial people but on the ships themselves.
- _aavaa_ 3y agoThe problem, just like for car, is the volume that hydrogen takes up, not the weight
- credit_guy 3y agoAnother place where it could make sense is trains. Building overhead power lines could be expensive, especially if we are talking about high speed trains. Because of the square cube law, large pressurized tanks could be economically quite efficient. A train could carry an extra car with a pressurized tank at 700 bar. At this pressure the hydrogen density is 42 kg/m3. A typical oil car has a volume of 131 m3, so assuming the same volume, we'd get about 5.5 tons of hydrogen. Hydrogen has about 3 times the energy density of diesel fuel, and hydrogen cells about twice the efficiency of diesel engines, so all in all 5.5 tons of hydrogen would be the equivalent of about 33 tons of diesel. That's more than enough to move a train from one train station to another one, even if the stations are hundreds of miles apart.