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this post was submitted on 08 Jun 2024
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micromobility - Ebikes, scooters, longboards: Whatever floats your goat, this is micromobility
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Ebikes, bicycles, scooters, skateboards, longboards, eboards, motorcycles, skates, unicycles: Whatever floats your goat, this is all things micromobility!
"Transportation using lightweight vehicles such as bicycles or scooters, especially electric ones that may be borrowed as part of a self-service rental program in which people rent vehicles for short-term use within a town or city.
micromobility is seen as a potential solution to moving people more efficiently around cities"
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Hydrogen for mass- or space-constrained mobility (eg bikes, automobile, aircraft) faces all the known problems with storing it inside inconvenient shapes and contending with the losses from liquification. Real Engineering has a video on this aspect (Nebula and YouTube) when compared to simply using battery-electric storage.
However, I think hydrogen could be very useful for train locomotives -- which historically had "tenders" that stored the fuel behind the prime mover -- since weight is less of a problem on traction railways. As well as any stationary applications, such as utility-scale hydrogen to time-shift electricity supply, where there may be scales-of-efficiencies to realize. Today's utility-scale battery farms are not exactly gaining any scales-of-efficiency to speak of, because they're just adding more battery cells to the grid.
A singular, massive hydrogen storage tank would be a sphere, benefitting from a favorable volume to surface area ratio, among other possibilities. And such a sphere would make better use of land by growing in height, whereas multi-storey battery farms would be fire hazards. But these are just cursory conjectures.
Where a battery bank has a hazard of starting a fire as well as being a hazard if there is fire nearby, an enormous hydrogen tank is only a hazard if there is fire nearby, but it's an explosive hazard.
How would it compare to storing enormous amounts of propane, in terms of safety only? Would the same safeguards work?
Shorter term stationary storage seems like an interesting idea, has anyone studied it out to see how effective, affordable, and efficient it is?
Hydrogen leaks ! Dihydrogen is the smallest molecule so it can pass through the smallest smallest gap.
Containing hydrogen is extremely difficult and it is an extremely difficult challenge for rocket manufacturers.
Hydrogen is the future of nothing but energy scams.
It has the big advantage of easy long term energy storage. You can store power made by PV in summer and use it in winter.
It has the big advantage of easy long term energy storage.
Citation needed. Hydrogen leaks in spaceflight (where hydrogen is often used as a rocket fuel) is incredibly common because H2 is so freakin' tiny.
In the future please be more clear you're introducing a whole new step of conversion of hydrogen to ammonia, and then yet another step of conversion from ammonia back to hydrogen for use again. That's not quite the "easy long term storage" your comment described.
It’s easy compared to the alternatives and time span for energy storage. You can de-couple production of energy with consumption. You can transport energy by help of hydrogen either by frozen, compressed gas, cold ammonia or through pipelines. That’s easy and hands on.
Try to transport energy through batteries. Duh. Or fusion energy (somewhen). Or nuclear energy. You always need a power grid.
You can transport energy by help of hydrogen either by frozen,
CRAZY energy intensive to freeze hydrogen into a solid, and keep it stored below (–434 ºF; –259 ºC) in a storage container to prevent boiloff. Even cryogenic liquid hydrogen (at -400 ºF or -240 ºC) is a pain in the butt to deal with and store, again for boiloff reasons
compressed gas
Hydrogen is a horrible compressed gas to store. Thats the part that everyone is jumping on you about in this thread. It has to be at very high pressure, is still very low density, and leaks out of all but the best fittings and valves because of how small the H2 molecule is.
cold ammonia or through pipelines.
Ammonia may be the best form to convert hydrogen to, but that doesn't make it good for the general use cases we're looking to replace, meaning energy generation. You're also handwaving away the entire infrastructure needed to convert excess hydrogen into ammonia, and then back again into hydrogen if you're not using it as ammonia directly (which I haven't seen you suggest yet).
That’s easy and hands on.
That's far far from easy, and its destroying your argument of a hydrogen intense future if you keep doubling down on it.
I‘m not saying hydrogen for every use case. No. German style of arguing? Just kidding, we Germans tend to opt for one or the other, but rarely an in-between or mix.
H2O has it’s advantages in terms of transportation and long-term storage. Same as petrol, oil, and gas btw.
We need new infrastructure for the entire energy chain being based on battery, PV, wind, SAF, hydrogen, whatever. Stronger power grids, daily battery storage, electric transformers, pipelines, harbors, h2o/ ammonia generators, fuel & loading stations, all that stuff. For each of the other energies but carbons. I don’t know what’s this argument is about.
Aren't there significant challenges with storing the smallest molecules in the universe?
The water is cheap but the hydrogen requires special pressurized containers which in turn makes it lose its advantage over normal batteries.
Yeah, it blew my mind that the Toyota Mirai's hydrogen tanks are pressurized to 10,000 psi. To store a decent amount of hydrogen you need compress it to crazy high pressure or cool it with liquid helium or some other exotic extreme cooling. The thing about hydrogen that always confused me is that hydrogen is very energy dense but it physically not very dense.
It's not really energy dense. It's the single lightest atom in the universe, meaning it stores the lowest amount of energy. But it's very reactive chemically.
I wonder if the water is drinkable, that would be pretty cool if your bike also produced hydration on rides so you wouldn't have to carry extra water.
The hydroride site says the green bottle contains 20g hydrogen, that might make 180g water, but is still not a lot if you're thirsty. But can 20g of Hydrogen really take a bike 60km ?
Maybe? Warning Half-asses napkin math here but there are 286 KJ in a gram of hydrogen. So that 20 grams has 5720 KJ which converted to Watt hours is 1589 Wh. From my googling hydrogen fuel cells are 40 - 60 percent efficient. So half that to 750 Wh. Which is comparable to most e-bikes rated for 20Km of range. There are some issues with hydrogen. Converting water to hydrgron is only 70-80% efficient and converting that hydrogen to electricity is 30-60 percent efficient. Compare that to li-ion battery which can be charged at close to 99%. That mean hydrogen waste so much more electricity. Which is why I'm a hydrogen hater. I much prefer putting solar energy directly into batteries instead of the converting it hydrogen and back again at great lost.
Your hydrogen efficiency estimates are probably pretty close to what this bike can do. The lithium ion comparison is missing some losses, ~90% efficiency from voltage boost converter. Also, the hub motor/speed controller both add another 75% efficiency to the equation but this applies to both so we can negate it.
As for being a hydrogen hater, what did hydrogen ever do to you? I think we'd all prefer a solid state solution that would minimize losses but we don't have enough battery infrastructure to accommodate all of our needs. Sure, hydrogen is not the panacea for fossil fuels or lithium batteries in cars but there are good uses for it. I think Hydrogen can potentially be a good replacement fuel for large shipping vessels like ships and trains, since size requirements aren't as much of a factor, or used in grid storage as a long term or spillover storage for renewable energy when battery infrastructure is at full utilization and other means aren't available.
I didn't think about hydrogen powered shipping container ships. That sounds like a good use case.
My main issue with hydrogen is that most of it is produced using some natural gas / fossil fuel thing I don't understand. AKA Dirty hydrogen. Producing hydrogen using green tech is super inefficient compared to storing green energy in batteries. Personally, I think better battery tech like sodium Ion that uses cheap and recyclable materials are the better option for most applications.
I do have a personal conspiracy theory that fossil fuel is pushing for hydrogen to slow green tech epically since the cheap way to make hydrogen is with fossil fuels.
Another thing about hydrogen is storage and transportation. To store it long term you need to cool it a liquid form which is really hard to do. Also, current hydrogen fuel cell are low efficiency and low power density. That's why the toyota miria uses a fuel cell to charge a battery which powers the car.Tthe fuel cell can't put out high current.
Most of what I know about hydrogen tech came from the aging wheels video about Mirai. So I might be super wrong about everything. I do recommend giving it a watch though: https://www.youtube.com/watch?v=rtZQLUtckS4
You're definitely not wrong. Gray hydrogen currently is the most common source, which is a byproduct or an intended product of petroleum cracking. This also is probably a reason why most petroleum companies chose to research hydrogen in the 2000s/2010s rather than battery or other renewable technologies, since it fits nicely in their existing pipelines.
For storage, I'm pretty sure you can keep it at atmospheric pressure and temperature if space isn't an issue, but to actually fit it in a vehicle you'd probably have to use one of the techniques you mentioned.
The Mirai's issues seem to be that it was just a foothold for consumer hydrogen without anything really backing it. You could almost say the same about EVs/PHEVs 15 years ago and look at them now.
Honestly though, if we are able to scale up sodium batteries, grid storage and train usage might be moot. Ships could probably still use it as an alternative to diesel though.
You would lose electrolytes though, you would need to bring them on longer trips.
Doesn't look like it produces a lot either, so yeah, I guess it could only supplement your water supply.
You'd have to sweat a lot for that to be a factor. Not that it is irrelevant, but humans can drink distilled water just fine. In fact, there are regions, where bottled water is almost exclusively distilled.
So as long as you don't plan to participate in the Tour de France, you'll be fine.
When hydrogen reacts with oxygen it produces pure water. Pure water is quite reactive and will leave chemical burns on your skin. The reason is that pure water will try its best to absorb minerals, etc. And your body contains a lot of minerals and other stuff. Never drink chemically pure water!
Pure water is not going to burn you and you can even drink it (though, over time, it can leach minerals from you but then again so do carbonated beverages). People buy distilled water all the time.
Distilled water is not pure water.
What do you mean by "pure water" then? What exactly are you referring to?
Edit: Ok, it looks like judging by your other post, you're referring specifically to type II deionized water. That is not really what people immediately think of when you say pure water. Also, it's not going to burn you unless you boil it.
What else can you think of seeing "pure"? If it's not chemically pure, then it's not pure.
Literally any purified water or other variety of distilled water would probably come to mind for most people.
Where did you hear this? You're talking about distilled/unmineralized water not an acid.
Hydrogen as a use case only works for already very heavy vehicles like trucks. Even for normal cars it's a stupid idea.
Now using it for small mobility, thats maximizing idiocy.
I think you're being a little too generous; the only use-case where I'm aware of it being optimal is rocket fuel. Trucks retain their fuel for long enough that storage and leaks become a problem unless you have impractically heavy tanks.
I think trains and excess generated wind/solar energy storage are also use cases.
I still think these strange sounding, deadend ideas (like hydrogen bikes) still have some use, because you don't know what helpful discovery might be found, even in failure to accomplish the main objective of the project.
Excess from wind and solar are better handled by mechanical energy storage. The two examples I'm aware of are magnetic flywheels and Pumped-storage hydroelectricity, each working on a different scale. Thermal energy storage should also play a role in specific applications. A flywheel (or a battery thereof) in every basement would help smooth out any electrical failures, potentially holding things over for hours at a time, enabling extremely resilient energy infrastructure. Pumped-storage hydroelectricity is extremely cheap and efficient for what it does; I'm not aware of any options that are better, so long as you're cool with a lack of mobility and want something very large-scale.
I'm not super familiar with the numbers when it comes to trains specifically, but I'm definitely skeptical. As far as I'm aware, one of the reasons it works for rocket fuel is because that application immediately and completely uses the fuel, and so leaks are a relatively small problem. Another is that hydrogen's weight scales very favorably (it's the lightest fuel we suspect to be physically possible), and rocket efficiency is highly dependent on fuel density per joule. Trains can accommodate very high loads, need to hold energy for long periods, and don't get a huge benefit from reducing the mass of the energy storage system as they go; it's entirely possible that flywheels beat out hydrogen (Note: the main disadvantage of flywheels is that they are heavy, and so are not generally optimal for vehicles) and I have a hard time imagining hydrogen beating out rechargeable batteries, but again I'm not familiar with the numbers and so cannot say for certain.
you don't know what helpful discovery might be found
That's entirely fair; experiments are never worthless. However, our current understanding still makes hydrogen bikes extremely unlikely to be effective.
I could see it working for ride share but I also can't imagine anyone attempting that.