This is all irrelevant to the question of whether it would leak enough to be a greater greenhouse issue than burned jet fuel. As I established in another post in reply to you just now, that would need to be nearly a quarter of all of the hydrogen used in such a system. That is an extremely unlikely scenario.

Once again, I am not talking about any of the other logistical questions about using hydrogen like this. Only the greenhouse gas issue that came up.

There's no doubt that it's very iffy if this would be more suitable for aviation than other synthetic fuels. There are lots of potential issues. However the greenhouse warming potential as an issue just doesn't make mathematical sense. As far as 37X vs 12X, doesn't really matter since I addressed 37X in my post.

To cover it again, GWP is by mass. So, if 1/37th of the mass of CO2 in hydrogen is released, we're saying it's just as bad. However, we have to start by considering that we're not burning CO2 in engines, we're burning other fuels. In jets, we're burning jet fuel. That's just kerosene. Kerosene has about 12 kWh of energy per kg. Hydrogen has about 34 kWh of energy per kg. There are all sorts of practical questions about volumetric efficiency, etc. but all other things being equal, you use about 2.83 times as much hydrogen for the same air mileage as jet fuel. At the same time, the CO2 released from the jet fuel is about 3X the mass of the original fuel. So, right off the bat what we have a multiplier of about 8.49 we need to consider. In other words, if hydrogen is 37X as bad as a greenhouse gas as CO2, then 37/8.49=4.36 is the actual number we need to consider. In other words, for hydrogen as a fuel to be as bad as jet fuel, then 22.94% of the hydrogen has to outright leak in to the atmosphere. Despite potential issues containing hydrogen, this would be extremely unlikely.

We can get into externalies, but if we compare externalities for synthetic hydrogen vs. jet fuel, the hydrogen is still going to look better from a greenhouse gas perspective than the jet fuel. None of this is to say, that hydrogen would actually be better considering all of the other obstacles, but it clearly would not be as bad in terms of greenhouse contributions.

Well, I didn't really go into it there since I was just responding to the specific claims from the poster I responded to. For what you mentioned, I will first point out that an extensive power grid significantly mitigates Dunkelflaute. However, when it is nationwide, I should also point out that, in my post, I explicitly ignored other power sources and storage methods like geothermal and hydro/hydro storage. If we don't ignore those, we get an additional buffer. What I think is that we should have a tiered storage system.

This would mean batteries for the standard short term. Meaning enough to cover the average deep winter night with average usages that the poster I replied to mentioned and then a little bit extra. That would provide coverage nearly all the time. 99%+. To supplement that, a secondary tier based on locally available resources, such as geological ones. That means hydro storage of various kinds (reservoirs, polders, underground, etc.) where practical, compressed or liquefied gas in underground reservoirs where practical, thermal storage in, for example, molten salt, etc. Basically, whatever is cheapest and makes use of available local resources. Where tier 2 is less practical than tier3, skip straight to tier3. Tier3 is longer term stable storage. This means things like synthetic methane (or even hydrogen if you can store it effectively), or synthetic liquid fuels. Also other substances, for example metal powders such as aluminum powder that you can burn in a thermal power plant, or use in some sort of flow battery, etc. then collect the oxides and use an electrolytic process to turn them back to metal powder again after use. There are all kinds of other options. Dehydrating zeolites, reservoirs of salt water and and fresh water where you generate power across a membrane between the two tanks then reverse the process with reverse osmosis to recharge, or basically any chemical process you can use to store energy that can be reversed with a reasonable energy loss, is relatively cheap at large scale, and that you can store in volume.

Basically, you would size your renewable power generation so that it would produce just enough on average in the dead of winter to power everything during the day and overnight on battery, which would mean plenty of surplus during other parts of the year. Whatever surplus there is in winter could charge the tier2 storage and, if it doesn't get enough for that, tier3 could be tapped to top up tier2. With all the surplus in the rest of the year, tier3 could be filled up and for tier3 storage types, that could last very long term and for many of them, increasing how much you can store could be quite cheap and simple. Of course, the tier3 storage would generally have much lower turnaround efficiency than batteries, but that would not be a problem because the surplus would be wasted otherwise.

To clarify, when I say it won't leak that badly, I'm not using a colloquialism. I'm literally saying that it won't leak as badly as would be sufficient and necessary for the amount to leaked to produce enough greenhouse warming to exceed the greenhouse warming that the replaced fossil fuels would cause. It would have to leak enormously to do that and we have enough experience to know it would not leak that much. So I'm really only thinking about an upper limit to the leaking.

I do completely agree with you that, with the right materials and techniques, the leakage could be very small. It still does present a worry in airports with lots of planes fueling at once. I'm sure acceptably safe protocols and fueling hardware could be established, but I can also see why it might reasonably make a lot of people nervous. In any case, there are a number of other hurdles to getting hydrogen planes to work, I just felt the need to point out that the complaint about greenhouse potential was misplaced. In terms of potentially viable technologies, for now, my money is on either getting conventional rechargeable batteries good enough, or on metal-air batteries, even if they're swappable primary cells (that can be "recharged" by reprocessing the metal oxides at a plant at the airport) as opposed to directly rechargeable versions. For medium distance flights, anyway. For long haul, we may have no choice but to use liquid fuels for now, but they don't need to be of fossil origin. The Navy is testing units to produce jet fuel from seawater currently. We'll see if that technology translates easily to civilian use and if it's sufficiently economical.

Interesting thing to note though is that you can actually see nearly 60% of the moon from Earth, just not all at the same time. Since the orbit of the Moon is slightly elliptical, it appears to rock slightly from the point of view of Earth, letting you see a bit more on one side or the other. Also, you can see a tiny bit over the lunar poles from high and low latitudes on Earth.

Why would you need to bring it down to Earth background levels? Humans can survive considerably higher than that.

Maybe you might be taken a bit more seriously if you A. didn't act like you had some special, secret knowledge when everyone here already knows that there's radiation in space. B. Actually presented some numbers about actual expected radiation dose in the situations you mentioned and compared them to known human radiation tolerances and standards (such as for radiation workers in power plants, etc.) and C. actually considered the radiation mitigation strategies that are already employed and proposed for future space travel.

I've heard more like 12x. Even at 37x though, it seems like H2 from non-fossil sources would be far better than CO2 producing fossil fuels. Even at 37x, it comes down to whether the use of hydrogen as a fuel would displace 37x as much or more CO2 from being introduced into the atmosphere. Basic logic says it probably would. Consider, with fossil fuels, essentially the entire mass of the fuel plus about 3x its mass becomes CO2 in the atmosphere. Essentially, every last drop of fuel ends up as atmospheric CO2 with a 4X multiplier. So, that would mean that something like 10% of the hydrogen fuel would need to end up in the atmosphere to be as bad as a greenhouse gas. Now, hydrogen is hard to contain completely, but it still tends not to leak that badly.

Then there's the fact that displacing methane usage with hydrogen would lead to significantly less methane in the atmosphere in the first place, so there would be less methane for it to extend the lifespan of. There are other effects hydrogen may have that would also contribute to global warming, however, so it would not drop to zero even if methane were eliminated entirely.

We also need to consider that this is for air travel. Hydrogen in other uses such as cars, etc. is unlikely. For most purposes, battery technology would be preferable. This would just be a potential solution for modes like air travel, where battery weight might make it prohibitive. So that means that the actual overall usage for it would be far less than for fossil fuels in general.

So, looking at it, that seems to suggest that, even if it has more warming potential, the net effect would still be a reduction in warming. Of course, that's not the only consideration for hydrogen. The extreme flammability is a concern, along with hydrogen embrittlement of containment vessels, the turbines themselves, etc. So, there are some questions about viability.

Overall, your argument seems overblown. Any industry currently using fossil fuels would still be doing better from a greenhouse gas perspective if it moved to green hydrogen (obviously not to hydrogen from fossil fuel sources).

AI has been running at a big loss to get the users hooked. It was inevitable that prices would start climbing. That process is nowhere near done, running AI is expensive as hell.

Once the market starts reflecting the actual costs, you can bet the cost/benefit will not be nearly as rosy as it looks now. But some customers will already have gotten themselves between a rock and a hard place and will be sucked dry, then discarded. Those "expensive" people that are getting dumped will start looking like a bargain, but they will have already been snapped up by smarter companies by the time management that can't see past their own toes figures that out.

All of this makes me remember a short story reading assignment in the 5th grade. It was about kids growing up in a society where machines did all of the intellectual work. To them, writing was 'squiggles'. They managed to disable a filter on their "bard" (a story teller for children) and had it tell them a tale of machines ruling over Man.

Nobody expects prophesy from a 5th grade reading assignment.

According to the Guinness Book Of Records, the Artemis II flight is the most expensive game of Hide and Seek in Solar System history! :D

"Fluid" intelligence is the ability to think, reason, solve problems, and learn things. "Crystallized" intelligence is your amassed knowledge.

These are technical terms used in the literature.

Intelligence is nature's guess as to how complex your environment will be... but there's an out. People with low fluid intelligence have to work harder to understand things, but if they put in the work they can amass a body of knowledge that rivals that of people with high fluid intelligence.

And of course, lots of people with high intelligence stop learning in their mid twenties. At that point they've conquered their environment and are living successful lives (good job, married, kids &c) so there's no real reason to push themselves. Lots and lots of people, even smart people, haven't read a single book in the last year - and this observation was true in the 1970's before the internet.

(And nowadays this is probably more accurate due to the appalling quality of information found on the internet.)

It's a question of training. We're evolved to believe what people say, it's a way of reducing the cognitive load of learning things (by believing what someone else has already figured out). We're not used to questioning the logic of someone else's beliefs.

As an example of this, note that Warren Buffet has built a career on identifying fallacies in business, google "Warren Buffet fallacies" for a list.

None of these fallacies is taught in school, everyone has to find them and figure them out on their own. And then you have to use them in your daily lives.

Almost no one is used to doing that, which leads to the current problems with AI.

That's a weird understanding. Are you on a lot of heavy drugs? While burning biomass is one form of renewable energy, it's hardly exclusively what is meant when people say "renewable energy". You also missed the part where you don't clear cut forests. Whatever you're growing, you grow it in a sustainable way. If it's trees, you use sustainable forestry techniques like they're supposed to use in the lumber industry (certainly you should not be cutting down old growth forests). Of course, if you're growing just to burn biomass, large trees are not the way to go. Willow, poplar, eucalyptus are some trees that have good yields for burning but bamboo or giant king grass might be better in many locations. Also, when you say that burning trees is far more polluting, you have to define what you mean. In terms of CO2, it's certainly not because it's a closed cycle. The CO2 that goes into the atmosphere came from the atmosphere in the first place and in the recent past, so you maintain equilibrium. As for other pollutants, it's not actually very polluting at all if you do it properly. You're probably thinking of an open fireplace. Consider, however, a three stage catalytic wood burner. First stage is typical burning like in a fireplace. However, the heat from that heats up a sinusoidal pipe that's bringing in more air, heating it up and that air is mingled with the hot smoke, burning the unburned material in the smoke. Then, what's left goes through a catalytic burner that's pretty much the same thing as a catalytic converter in a car. That does a final burn of just about everything remaining including polluting nitrogen compounds. The final result is that basically everything that can be burned is burned and the exhaust is very clean. Do basically that on an industrial scale and add a scrubber and you've got a relatively non-polluting system. Of course, it's not absolutely perfect That though, is why you're better off with solar panels, wind turbines, etc. You know, the renewables you ignored in order to have a nice strawman to attack.

But none of them normally need 100% battery coverage. It's all about figuring out the risk of a period of downtime over a wide geographical area and what amount of risk is acceptable. Just like with other power sources.

Ah. Of course. Missed that one. Doesn't help that I inverted the direction since I didn't think it mattered. Thanks for pointing that out. Of course that means that the distance was not carefully chosen to be right in between typical ranges for BEVs and ICE vehicles, it was just a coincidence. Not sure what to think about that. I assumed that the poster was being manipulative with the choice, but at least clever. Now it looks like I have to drop the clever bit, but give them more credit for not being manipulative... I think it ends up being mostly a wash.