Can anyone here speak to the practical aspects of making fuel cells work at this scale? What exactly needs to change to gets the costs more in line with ICE vehicles?
From memory, so it might be wrong and probably outdated:
- the cells themselves weren't exactly cheap (lots of platinum) but that was IIRC non-recurring cost
- storage is non-trivial due to hydrogen embrittlement and the like, while methods that are safe from it have other issues. Toyota has, AFAIK, this year or last year presented a serious improvement in that area with removable, rechargeable hydrogen cartridges - even if they break, less expenditure to replace, plus they make off grid operation much easier
- hydrogen has a chicken and egg situation where vehicles need a robust network of charging stations but to build such network you need customers - a circular dependency. According to NIST studies on the topic, charging stations with in-situ electrolysis equipment and only a buffer tank are best option, so you effectively have same requirement as for BEV chargers plus source of clean water
Note that BEVs made a run around the problem by having early adopters depend on home chargers that offered enough range for city driving - essentially validating the need for charging network by having cars already on the road. (subsidies helped of course)
That said, energy density of hydrogen is orders of magnitude better than batteries, so unlike with electric cars the question is not "we need unknown new technologies to get effective long range truck" but just a matter of money to actually turn prototypes into operational model.
Hydrogen and BEV trucks will probably both need to follow the model of picking a specific route and converting that, by adding infrastructure, and getting multiple companies to spread the costs.
Shipping is doing something similar with Green Shipping Lanes.
But many trucks and heavy duty vehicles have already experimented with alternative fuels like CNG fueled from their own depot, so it's probably only needed as a second step as use widens.
The Toyota Mirai platform is impressive, although it is still heavily subsidized.
I guess my question was about the cells themselves, though, and less about H2 production / storage. I’m reading that the newer fuel cells have much less platinum— on the same order as a catalytic converter.
If I try to buy a hydrogen fuel cell on the open market, they seem to cost around $10k per kW. Which makes Mirai that much more amazing given that it’s 114kW! I wonder how that’s even possible…
I think the use of platinum catalysts is a current driver of costs for the fuel cell.
There's similar issues on the electrolyzer side but I think cheaper alternatives are entering the mass production stage. Presumably people are looking for similar breakthroughs on the fuel cell side.
Plus the subsidies for using polluting fossil fuels cramping the market, though they are, very slowly, being reduced.
Worth remembering that FCEVs were in fact better than ICE for various reasons, but still not as good as BEVs, which is the main challenge for trucking as well, but better BEV trucks also improves FCEV trucks as they reuse a lot of the same tech stack after the hydrogen becomes electricity.
If the high-tech part is the fuel cell, then extending range would be simply a matter of adding relatively low-tech gas tanks. Heavy, but not something that would fundamentally limit the range.
Or are their innovations in hydrogen storage as well? Do their "fuel-cells" store hydrogen which is converted to electricity elsewhere?
Technically, a hydrogen truck is an electrical truck with an undersized battery that is topped up via a hydrogen fuel cell. Fuel cells don't really throttle up or down very well nor do they typically match the peak output of the engines, typically. So you actually need a fairly big battery if you drive into e.g. mountains.
You can trivially improve energy efficiency by just using a bigger battery and getting rid of all expensive and inefficient hydrogen parts. By about 3x. Energy conversion from electricity to hydrogen involves losses, converting it back to electricity adds more losses. And hydrogen is hard to contain and there are losses involved with storing and transporting it as well. Transporting it of course involves using trucks. Which require energy. End to end it doesn't look good. About a 3x difference or worse in terms of energy efficiency.
Producing hydrogen from clean electricity is a lot less efficient than simply dumping that electricity in a battery and using it. And since trucks are designed to haul lots of mass around, have engines with lots of torque, etc. a big battery is much less of a concern. Besides, hydrogen also takes up a lot of space. What it boils down to is the cost of the vehicle and the cost of the fuel (3x). Which is to say that using hydrogen for transport does not make a whole lot of sense.
That's a huge cost advantage for battery electric trucks. And it's the reason that there are multiple manufacturers are already producing those in just about any weight class and form factor you can name. Including some long range heavy trucks, extremely large mining trucks, etc.
The few manufacturers that also peddle hydrogen (Like Nikola) are increasingly focusing on battery electric trucks at this point. But they seem happy taking the subsidies for continuing hydrogen development. That is of course the point; without subsidies most manufacturers would immediately pull the plug on their hydrogen programs. Toyota included. They have very little hope of ever producing vehicles that are cost competitive with battery electric at this point. Certainly not this decade. At best you might argue that electricity will one day be so cheap that the inefficiencies stop mattering. But that's not happening any time soon.
And of course recharging vs. refueling is a popular argument in this space as well. Filling up hydrogen tanks is very unlike fueling a diesel truck. It involves very high pressures and pipes/valves with relatively small diameters. It can easily take twenty minutes or more. During that time you could also dump a lot of electricity in a battery. Besides, truck drivers have mandatory rest periods that are much larger than that. So a 40 minute break is not that big of a deal for a long haul truck driver.
And all of that assumes you'd actually have filling stations that you can use. Those don't exist yet in most places. And probably won't for a long time. Charging stations on the other hand are popping up all over the place.
And there's the slight issue that methane just got a lot more expensive which means that converting it to hydrogen for the purpose of converting it back to electricity is now an even worse idea than it already was. And the main plan for hydrogen producers was to use grey (mostly) and some blue hydrogen for the next few decades. I.e. methane conversion without or with (some) carbon capture. This is bordering on criminally insane from a carbon emissions point of view. The notion of using grey hydrogen for transport for environmental reasons is ludicrous. You'd be using about 6x the equivalent in methane. You are better off using that methane as a fuel directly. Green hydrogen at large scale will require way more wind mills and solar panels to be installed than is needed to electrify fleets using battery electric.
Hydrogen tech is a bit of an odd one to me since people rarely talk about the one good thing about it that might offset the otherwise just straight bad performance, you can store it for a long time!
So in a world with truly massive renewable energy surplus during peak hours/days/months maybe hydrogen vehicles will make sense as a way of making use of this very inefficient but shelf stable form of storage.
Until then I really don't see why people are getting excited about something that is a lot worse than battery electric in a lot of ways
It's just a matter of scale. make your tank 4 times as big and the surface area for leakage only grows by a factor of 2.
also there is already a natural gas grid that can take a lot of hydrogen without modification.
Again this really only ever makes sense if you have an absurd energy surplus as a sort of last resort way to use energy that would otherwise go unused.
In terms of actually being a desirable power system it seems like a complete nightmare to deal with unless you need to go really far out on the gravimetric energy density front with very low power density all while having a fraction of the efficiency of battery electric
ah yes sorry got mixed up a bit there. a doubling in linear size leads to a quadrupling in surface area and an 8 fold increase in volume and then I somehow got confused from there m)
nevertheless increasing size improves the situation
How does that improve the situation? One spark and it all goes boom. It’s not the relative size of the leaks to the volume of storage that matters, it’s the fact that even a small leak will go boom very easily.
Nah, in this context they are talking about hydrogen having so small molecules that it escapes from all containers you put it in. Increasing size of container decreases relative leak per volume (due to previously explained math).
Problems of the booming nature is a different topic.
Hydrogen vehicles are interesting (especially for things like public transport where battery capacity can be an issue - some cities have started looking at hydrogen buses for longer routes for example) but it is potentially pretty good as a potential grid level storage technology as well, even if cars largely become electric.
The thing is that the vehicles really aren't interesting at all unless you already have an energy surplus that makes the fuel cheap.
unless you have that all you have is a vehicle that burns an expensive and or non renewable fuel (most hydrogen right now doesn't come from electrolysis) while getting just ok range and with the included headache of carting around a 700bar storage system and dubious ecological benefits over bad old hydrocarbons
We do have an energy surplus, we're just currently wasting a ridiculous amount of it for no particularly good reason.
Take the gas burned in homes for heating, burn it in power plants to generate electricity, power much more efficient heat pumps. We're already saving money and energy. Some countries figured this out in the 1970s.
Simultaneously, build out cheap renewables, to burn less gas for electricity production.
Same story for vehicles, take that oil/gasoline, burn it in power plants, use it to charge much more efficient EVs.
Hydrogen then can replace fossil fuels in other areas, e.g. fertilizers. (Again, put that now unused gas into electricity plants).
And so on, a virtuous cycle that takes you all the way to net zero and beyond.
In my area there are a lot of electric city buses in use. AFAIK battery capacity isn't really an issue - they just charge them at the depot and then they're good for a day of use. Regional buses still tend to be natural gas-powered, though.
Like most technologies, there are upsides and downsides. There is no need for everything in the world to be powered the same way, use what makes sense in each context.
For long distance heavy trucking, batteries are both very large and heavy. Hydrogen can offer an alternative there.
For air travel, batteries are very very heavy. Hydrogen is as far as I can google comparable with gasoline on that front, so an attractive proposition there as well.
Hydrogen fits into several different markets really well. And those opportunities taken together may well outweigh the limitations. Being able to exchange one form of energy for another is useful. Having lots of potential customers is beneficial. That is why I am excited about Hydrogen. The ecosystem is the most important thing and gives a critical mass. Its a big potential ecosystem...
* It can use spare renewable energy.
* It can be made with spare nuclear energy.
* It can be an input for large scale industrial processes like fertilizer production.
* It can be stored in old gas fields.
* It could be blended with natural gas and burned.
* It is a promising airline fuel
* It fits in well with existing oil infrastructure.
* It may be a fuel for vehicles and trains.
And many of these elements could exist within a small area. An oil refinery, chemical works, offshore windfarm, a few modular reactors, gas fields, natural gas exports, rail line, airfield. All within 50km and all potential suppliers and customers.
Blue Hydrogen seems to have mostly died for economic reasons, Gray Hydrogen sadly is still being produced, though perhaps not for much longer. Blue hydrogen was mostly used as a 'jedi hand wave' to keep the Gray Hydrogen going.
Also, we really need to switch from saying "It can use spare renewable energy" to "the renewable energy built to power it can, in times of need, be directed to the grid instead, replacing peaker plants".
Same thing essentially but just 10/90 vs 90/10 on how much is used for the new thing, and how much goes to the grid for traditional uses.
To put this in perspective this is exactly what is needed for some use cases. I live in Singapore. We are a small island nation with zero natural resources. Currently our energy mix almost exclusively dominated by fossil fuels. The move away from fossil fuels is right now impractical as we don't have the necessary land space for solar and we dont receive enough wind to justify wind power. There are no mountains for hydroelectric power. We also have a massive energy footprint thanks to air-conditioning and industry. We don't have many alternatives other than to either (1) import green energy or (2) use nuclear.
(1) poses defense and logistic problem. We become victims to the whims of our neighbours (politicians in our neighbouring country have more than once threatened to cut our water supply). While, we do import water from malaysia, we can also be fully self sufficient should the need arise thanks to desalination and rain water cachement. As a small nation we have a requirement to defend ourselves. Petrol is very convenient as we have massive reserves that should last us a year should we need to go into siege batteries on the other hand don't. Thus a hydrogen economy is a massive game changer for us.
(2) is something we may explore. But as a land scarce island with no prior nuclear technology, we would need to develop new technology from scratch. It could easily be decades before a sufficiently large yield and safe reactor becomes available. Hydrogen on the other hand has a shorter run way.
This tech is still years away from seeing mass adoption on the roadways, but Toyota is readying its powertrain to see production start next year. As a simple proof of concept, the folks at Toyota stuffed their powertrain into a Kenworth T680 and took yours truly along for a ride.
What is Toyota's plan while everyone else goes fully electric? Hope people just prefer a clunky old gas guzzler and high oil prices?
This kind of sentiment existed in the 80's and 90's when talking about electric cars. Then a lot of innovation happened and suddenly everyone wants one.
You are comparing 80s tech to now? Where we literally have high performance electric vehicles that cost less to run than their lower performance gas cousins.
It’s not arrogance to point out the obvious cognitive dissonance Toyota is experiencing, it’s stubbornness on Toyotas part to not acknowledge what is happening.
My guess is Toyota has done the math and as a volume car supplier it could never secure enough BEV materials to make the kind of volumes it needs to to maintain its current sales, so it’s betting / hoping on an alternative.
I think for the most part it's great for everyone, except perhaps Toyota - and perhaps not.
If hydrogen is a dead end, plenty of car makers are making battery electric cars, little loss to the future. But you never know what invention is just around the corner. It might just be a good bet.
Battery electric cars still have drawbacks that can be improved on, hydrogen is behind but it's great that alternatives are considered in earnest.
The subject of this article is a class 8 semi trailer. The economics in this space accentuate some of Hydrogen’s advantages of Lithium batteries.
For instance, trucks must meet certain maximum weight requirements to be legal on roads due the damage they might otherwise cause. Lithium based batteries store much less energy for a unit of weight, so designers must make a harsh trade off between cargo capacity and range. Toyota claims that their prototype has about twice the range than the BYD 8TT, which is an all electric class 8 semi trailer.
Depending on how the development of batteries progresses, Hydrogen based tracks may end up being the most effective way forward. At least, till there is a fundamental advancement in alternative energy storage mediums.
"The battery used in the 8TT has more than 400 kWh of capacity, which according to the manufacturer translates into an all-electric range of 124 miles at full load or 167 miles at half load."
While this seems more interesting:
"Tesla describes the Semi as "a Beast" - "More powerful, more efficient and fully electric. Semi is the future of trucking." The company has maintained the core numbers, including two battery versions for about 300 miles (483 km) or 500 miles (804 km) of driving range when fully loaded.19 Aug 2022"
JCB is another big player in the hydrogen space. For what I understand they are adapting their old diesel ICEs to work on hydrogen, whilst Toyota are using newly developed electric engines powered by hydrogen cells. Two very different solutions to the same problem.
How explosive is hydrogen on its own? Eg if I light a match to a hydrogen leak in air, how bad would it be? I thought it would just burn, without a pure oxygen counterpart. So comparable to petrol.
One memorable chemistry lesson at my school[1] involved the teacher bubbling hydrogen through soapy water, while a student stood on the bench with a lighted splint and set fire to the bubbles of hydrogen floating up. They didn't explode so much as rapidly burned. (Of course they didn't mix much with air first, probably if the bubbles had mixed air/H2 they would have exploded more?)
[1] Health and safety wasn't much of a concern back then. I also remember another lesson where we lined up and plunged our fingers into a beaker of mercury. Quite a weird feeling.
There will be better, more factual answers. But when I was about 10 we had a science show at school where they lit two balloons on fire - one with air or helium and one with hydrogen. They were about .7 meters in diameter. The second time the show came to our school, I knew what was coming with the hydrogen balloon, and, hating sudden loud noises, excused myself to the bathroom until it was over. I think I stayed there about 15 minutes before they had to come check on me.
So at least 15 10-year-old-bathroom-minutes explosive. In short, very loud. But if they do it repeatedly in front of a hundred children, probably not too much. I don't remember feeling any pressure wave.
But I'm guessing that a hydrogen leak in an enclosed space could easily result in a dangerous H2/O2 mixture.
It would be quite ironic if hydrogen vehicles ended up beating electric. Though it seems sort of silly given that hydrogen must be converted into electricity, but who knows.
I wouldn’t say ironic. Japanese automakers like Toyota were accused of being caught off guard by electric cars but the truth is that these companies have been developing hydrogen drivetrain and vehicle technology for a long, long time. Those that wonder why Toyota introduced the Prius and seemingly stopped short of an electric car after that haven’t been paying attention to what Toyota’s vision for transportation looks like.
> Though it seems sort of silly given that hydrogen must be converted into electricity
I would actually be curious to know if using an electric drive-train in a semi truck with a battery + diesel generator attached to it would be more efficient then a traditional truck anyways
I've noticed the suprising absence of hybrid trucks too. They do exist but generally don't get talked about about much.
I'm guessing that if you have a fleet, then a hybrid fleet makes more sense than hybrid vehicles in your fleet. Use the BEV for the tasks they are good at, and slowly edge out the diesel trucks as the BEV tech improves.
48 comments
[ 2.7 ms ] story [ 108 ms ] thread- the cells themselves weren't exactly cheap (lots of platinum) but that was IIRC non-recurring cost
- storage is non-trivial due to hydrogen embrittlement and the like, while methods that are safe from it have other issues. Toyota has, AFAIK, this year or last year presented a serious improvement in that area with removable, rechargeable hydrogen cartridges - even if they break, less expenditure to replace, plus they make off grid operation much easier
- hydrogen has a chicken and egg situation where vehicles need a robust network of charging stations but to build such network you need customers - a circular dependency. According to NIST studies on the topic, charging stations with in-situ electrolysis equipment and only a buffer tank are best option, so you effectively have same requirement as for BEV chargers plus source of clean water
Note that BEVs made a run around the problem by having early adopters depend on home chargers that offered enough range for city driving - essentially validating the need for charging network by having cars already on the road. (subsidies helped of course)
That said, energy density of hydrogen is orders of magnitude better than batteries, so unlike with electric cars the question is not "we need unknown new technologies to get effective long range truck" but just a matter of money to actually turn prototypes into operational model.
Shipping is doing something similar with Green Shipping Lanes.
https://supplychaindigital.com/logistics/green-shipping-lane...
But many trucks and heavy duty vehicles have already experimented with alternative fuels like CNG fueled from their own depot, so it's probably only needed as a second step as use widens.
I guess my question was about the cells themselves, though, and less about H2 production / storage. I’m reading that the newer fuel cells have much less platinum— on the same order as a catalytic converter.
If I try to buy a hydrogen fuel cell on the open market, they seem to cost around $10k per kW. Which makes Mirai that much more amazing given that it’s 114kW! I wonder how that’s even possible…
There's similar issues on the electrolyzer side but I think cheaper alternatives are entering the mass production stage. Presumably people are looking for similar breakthroughs on the fuel cell side.
Plus the subsidies for using polluting fossil fuels cramping the market, though they are, very slowly, being reduced.
Worth remembering that FCEVs were in fact better than ICE for various reasons, but still not as good as BEVs, which is the main challenge for trucking as well, but better BEV trucks also improves FCEV trucks as they reuse a lot of the same tech stack after the hydrogen becomes electricity.
Or are their innovations in hydrogen storage as well? Do their "fuel-cells" store hydrogen which is converted to electricity elsewhere?
You can trivially improve energy efficiency by just using a bigger battery and getting rid of all expensive and inefficient hydrogen parts. By about 3x. Energy conversion from electricity to hydrogen involves losses, converting it back to electricity adds more losses. And hydrogen is hard to contain and there are losses involved with storing and transporting it as well. Transporting it of course involves using trucks. Which require energy. End to end it doesn't look good. About a 3x difference or worse in terms of energy efficiency.
Producing hydrogen from clean electricity is a lot less efficient than simply dumping that electricity in a battery and using it. And since trucks are designed to haul lots of mass around, have engines with lots of torque, etc. a big battery is much less of a concern. Besides, hydrogen also takes up a lot of space. What it boils down to is the cost of the vehicle and the cost of the fuel (3x). Which is to say that using hydrogen for transport does not make a whole lot of sense.
That's a huge cost advantage for battery electric trucks. And it's the reason that there are multiple manufacturers are already producing those in just about any weight class and form factor you can name. Including some long range heavy trucks, extremely large mining trucks, etc.
The few manufacturers that also peddle hydrogen (Like Nikola) are increasingly focusing on battery electric trucks at this point. But they seem happy taking the subsidies for continuing hydrogen development. That is of course the point; without subsidies most manufacturers would immediately pull the plug on their hydrogen programs. Toyota included. They have very little hope of ever producing vehicles that are cost competitive with battery electric at this point. Certainly not this decade. At best you might argue that electricity will one day be so cheap that the inefficiencies stop mattering. But that's not happening any time soon.
And of course recharging vs. refueling is a popular argument in this space as well. Filling up hydrogen tanks is very unlike fueling a diesel truck. It involves very high pressures and pipes/valves with relatively small diameters. It can easily take twenty minutes or more. During that time you could also dump a lot of electricity in a battery. Besides, truck drivers have mandatory rest periods that are much larger than that. So a 40 minute break is not that big of a deal for a long haul truck driver.
And all of that assumes you'd actually have filling stations that you can use. Those don't exist yet in most places. And probably won't for a long time. Charging stations on the other hand are popping up all over the place.
And there's the slight issue that methane just got a lot more expensive which means that converting it to hydrogen for the purpose of converting it back to electricity is now an even worse idea than it already was. And the main plan for hydrogen producers was to use grey (mostly) and some blue hydrogen for the next few decades. I.e. methane conversion without or with (some) carbon capture. This is bordering on criminally insane from a carbon emissions point of view. The notion of using grey hydrogen for transport for environmental reasons is ludicrous. You'd be using about 6x the equivalent in methane. You are better off using that methane as a fuel directly. Green hydrogen at large scale will require way more wind mills and solar panels to be installed than is needed to electrify fleets using battery electric.
I doubt it's a great choice for long term energy storage.
We'll get there. its early days
Problems of the booming nature is a different topic.
Take the gas burned in homes for heating, burn it in power plants to generate electricity, power much more efficient heat pumps. We're already saving money and energy. Some countries figured this out in the 1970s.
Simultaneously, build out cheap renewables, to burn less gas for electricity production.
Same story for vehicles, take that oil/gasoline, burn it in power plants, use it to charge much more efficient EVs.
Hydrogen then can replace fossil fuels in other areas, e.g. fertilizers. (Again, put that now unused gas into electricity plants).
And so on, a virtuous cycle that takes you all the way to net zero and beyond.
For long distance heavy trucking, batteries are both very large and heavy. Hydrogen can offer an alternative there.
For air travel, batteries are very very heavy. Hydrogen is as far as I can google comparable with gasoline on that front, so an attractive proposition there as well.
* It can use spare renewable energy.
* It can be made with spare nuclear energy.
* It can be an input for large scale industrial processes like fertilizer production.
* It can be stored in old gas fields.
* It could be blended with natural gas and burned.
* It is a promising airline fuel
* It fits in well with existing oil infrastructure.
* It may be a fuel for vehicles and trains.
And many of these elements could exist within a small area. An oil refinery, chemical works, offshore windfarm, a few modular reactors, gas fields, natural gas exports, rail line, airfield. All within 50km and all potential suppliers and customers.
Although I am a bit uneasy about blue hydrogen!
Also, we really need to switch from saying "It can use spare renewable energy" to "the renewable energy built to power it can, in times of need, be directed to the grid instead, replacing peaker plants".
Same thing essentially but just 10/90 vs 90/10 on how much is used for the new thing, and how much goes to the grid for traditional uses.
(1) poses defense and logistic problem. We become victims to the whims of our neighbours (politicians in our neighbouring country have more than once threatened to cut our water supply). While, we do import water from malaysia, we can also be fully self sufficient should the need arise thanks to desalination and rain water cachement. As a small nation we have a requirement to defend ourselves. Petrol is very convenient as we have massive reserves that should last us a year should we need to go into siege batteries on the other hand don't. Thus a hydrogen economy is a massive game changer for us.
(2) is something we may explore. But as a land scarce island with no prior nuclear technology, we would need to develop new technology from scratch. It could easily be decades before a sufficiently large yield and safe reactor becomes available. Hydrogen on the other hand has a shorter run way.
What is Toyota's plan while everyone else goes fully electric? Hope people just prefer a clunky old gas guzzler and high oil prices?
Don't be so arrogant.
It’s not arrogance to point out the obvious cognitive dissonance Toyota is experiencing, it’s stubbornness on Toyotas part to not acknowledge what is happening.
My guess is Toyota has done the math and as a volume car supplier it could never secure enough BEV materials to make the kind of volumes it needs to to maintain its current sales, so it’s betting / hoping on an alternative.
If hydrogen is a dead end, plenty of car makers are making battery electric cars, little loss to the future. But you never know what invention is just around the corner. It might just be a good bet.
Battery electric cars still have drawbacks that can be improved on, hydrogen is behind but it's great that alternatives are considered in earnest.
For instance, trucks must meet certain maximum weight requirements to be legal on roads due the damage they might otherwise cause. Lithium based batteries store much less energy for a unit of weight, so designers must make a harsh trade off between cargo capacity and range. Toyota claims that their prototype has about twice the range than the BYD 8TT, which is an all electric class 8 semi trailer.
Depending on how the development of batteries progresses, Hydrogen based tracks may end up being the most effective way forward. At least, till there is a fundamental advancement in alternative energy storage mediums.
Quick Googling:
"The battery used in the 8TT has more than 400 kWh of capacity, which according to the manufacturer translates into an all-electric range of 124 miles at full load or 167 miles at half load."
While this seems more interesting:
"Tesla describes the Semi as "a Beast" - "More powerful, more efficient and fully electric. Semi is the future of trucking." The company has maintained the core numbers, including two battery versions for about 300 miles (483 km) or 500 miles (804 km) of driving range when fully loaded.19 Aug 2022"
[1] Health and safety wasn't much of a concern back then. I also remember another lesson where we lined up and plunged our fingers into a beaker of mercury. Quite a weird feeling.
So at least 15 10-year-old-bathroom-minutes explosive. In short, very loud. But if they do it repeatedly in front of a hundred children, probably not too much. I don't remember feeling any pressure wave.
But I'm guessing that a hydrogen leak in an enclosed space could easily result in a dangerous H2/O2 mixture.
I guess the "enclosed spaces" case matters for eg underground parking, maybe less in roads.
https://global.toyota/en/newsroom/corporate/37405994.html
https://georgewbush-whitehouse.archives.gov/ceq/hydrogen_090...
https://www.theatlantic.com/politics/archive/2015/01/george-...
I would actually be curious to know if using an electric drive-train in a semi truck with a battery + diesel generator attached to it would be more efficient then a traditional truck anyways
I'm guessing that if you have a fleet, then a hybrid fleet makes more sense than hybrid vehicles in your fleet. Use the BEV for the tasks they are good at, and slowly edge out the diesel trucks as the BEV tech improves.