The best balanced overview of hydrogen's future I've seen has been the Hydrogen Science Coalition: https://h2sciencecoalition.com/principles/

Green hydrogen is desperately required to produce fertilizer cleanly, so it is a problem that must be solved. It also looks very promising in a couple of other industrial processes, like the production of steel.

And that's about all we can say with any degree of certainty.

Why do fertilizer and steel require hydrogen in particular rather than just green-electricity-powered induction heating? Is the hydrogen meant to be a chemical component in the manufacture of fertilizer and steel rather than merely a heat fuel?

Hydrogen is needed for the Haber-Bosch process for making ammonia. For steel making, hydrogen would be used for reduction of iron ores to iron metal (currently, most of that is done with coke).

There's also a large market for using hydrogen to upgrade petroleum (hydrodesulfurization), but that market continuing to exist presumes some way of dealing with the CO2. Direct air capture, perhaps. There could also be markets developed to make synfuels from CO2 and hydrogen, or using hydrogen to upgrade biomass to get more fuel (hydrodeoxygenation).

There are various smaller markets using hydrogen. For example, making one of the precursors to polyurethane involves hydrogen as a reagent, as does manufacture of hydrogen peroxide.

> hydrogen would be used for reduction of iron ores to iron metal

Wouldn't electric reduction cells like those used in aluminium production work as well? Why would you need an input of hydrogen?

Indeed, electrolytic smelting is around and is currently used to produce high purity iron.

There are a few engineering difficulties arising from the high temperatures required and the chemicals around.

And note that aluminum smelting also releases quite a lot of carbon dioxide for various reasons, one of them being consumption of the graphite electrodes.

1. https://en.wikipedia.org/wiki/Electrolytic_iron

2. https://www.newscientist.com/article/dn9878-electrolysis-may... (2006)

3. https://link.springer.com/article/10.1007/s10800-017-1143-5 (2018)

Hydrogen production via electrolysis has the property that it can be turned on and off nearly instantly. Aluminum electrolysis in molten cryolite must be kept running to maintain the temperature gradient between the molten electrolyte and the walls (if not maintained, either the walls overheat or the electrolyte freezes, ruining the cell.) The temperature for iron electrolysis in molten materials would be even higher.

One can imagine electrolyzing iron in aqueous solutions, but I understand this actually needs more energy than producing hydrogen and using that to reduce iron oxide. There is some electrolytic iron produced today, for applications that require very high purity (as high as 99.999%).

Fertilizer requires the production of ammonia NH4. That is one nitrogen bonded to 4 hydrogens. The nitrogen can come from the air but the hydrogen has to come from some other compound.

Dumb question: why can't the hydrogen also come from the water vapor in the air?

That would be highly endothermic. The energy needed to separate the hydrogen from the water has to come from somewhere. If you meant "why can't we electrolyse that water to get the hydrogen", well yes of course that could be done, and that's what's being talked about (using water from some other source, though; why from the air?) But the water doesn't just decompose on its own.

You can, but doing so with renewable power would be under the rubric of "solving green hydrogen for industrial processes". In practice it's probably just easier to use renewably powered electrolysis to separate hydrogen and oxygen atoms from liquid water rather than try and use some chemical process to pull them out of the air.

Not dumb at all. Well, not exactly air, but that's how it's done. Air doesn't contain enough water, so you need to add some.

Currently nearly all ammonia is produced by "steam reformation" of methane in air (which is mainly nitrogen). Very hot steam, air, and methane are mixed. The carbon in the methane is released as carbon dioxide.

The idea is to take the methane out of the process.

Correct. It’s not purely for heating.

Science writer David Roberts had a long conversation with Rebecca Dell from ClimateWorks about decarbonizing heavy industry back in February. Lots more detail here if that’s of interest to you: https://www.volts.wtf/p/volts-podcast-rebecca-dell-on-decarb...

What about using hydrogen as a generator for an EV like in the Hyundai 74 concept? I’m far from an expert but something like that, at least intuitively, feels like a nice compromise with having portability of fuel, but still allowing for alternative power sources via electricity (like if grid power was sourced via solar, hydro, wind, etc).

Looks like the worst of both worlds at the first glance. However depends by the costs of batteries. In a world with an abundance/excess of green energy but expensive batteries to store it hydrogen makes sense. The conversion of electricity->hydrogen->electricity is quite inneficient so batteries better be expensive otherwise we will go the hydrogen way for cars as well.

I think you’re under the impression that it requires the hydrogen generator? You can use the hydrogen tank if you are without somewhere to charge the vehicle, but you can also just use it as a traditional EV and charge as you normally would.

Both hydrogen and batteries are energy storage technologies. My point is that it doesn't make sense to use one technology if the other is cheaper.

If batteries are too expensive then you would have an electricity -> hydrogen conversion at the power plat/wind farm.

Why not add a gas engine too, for places where you only have gas and not electricity or hydrogen? Because it's unnecessary weight to carry around. Toyota and Japan pushed hydrogen for a long time because their industrial base is so focused on gas/diesel drive trains. Their vast investments and expertise will be worthless as we leave it behind. They've also never made any progress getting away from hydrogen coming from fossil fuels. h is not a great fuel source because it's so much less dense than carbon fuels, you can't get far on one tank. It has two benefits, easy to refuel, and burning it doesn't produce pollution, but the negative of coming from fossil fuels kills it.

Fuel cells in the vehicle would be much more efficient. Combustion generators in the car have storage issues and efficiency issues. liquid hydrogen needs cryogenic storage, compressed hydrogen isn't space efficient relative to the output. Combustion generators at home would suffer from the same storage problems as in cars.

https://youtu.be/vJjKwSF9gT8

I don't understand what problems the Hyundai 74 is trying to solve. It has roughly the same stats as a long range model 3 for acceleration and range, but has to carry around both a fuel cell and a 60+ kwh battery (nearly as large as the model 3's). Hydrogen mpge is already terrible (all hydrogen mirai has 75 compared to long range model 3 at 130), and an extra step here is only going to make it worse.

Is there something I'm misunderstanding about the vehicle's platform?

refill vs recharge

Hydrogen makes no sense for passenger vehicles. It requires building out a massive infrastructure that doesn't exist and is just far less efficient than storing the elecricity in a battery.

Check out this video for more on where Hydrogen does and does not make sense: https://youtu.be/JlOCS95Jvjc

Now what happens as soon as there _is indeed_ sufficient H2 refuelling infrastructure for trucks? (Assuming that it will happen for long haul trucks because BEV trucks will not replace diesel powered ones in the long term)

Doesn't that make FCEV cars look a lot more convenient than BEV cars?

What is there problem with small vehicles?

EV's are about 3X as efficient turning electricity into motion as hydrogen cars are. Here's a good graphic from Volkswagen laying it out very clearly.

https://www.greencarreports.com/news/1127660_battery-electri...

Is it a suitable option for powering ships?

Batteries needed electric vehicles are still expensive and seem to essentially be the bottleneck for mass change to EV.

The infrastructure needed to support battery electric vehicles seem to be expensive/complex to run sufficiently well in practice. In the US Tesla's supercharger network is often cited as a moat against other manufacturers. It's not even building the chargers - it's maintenance and compatibility. Charger network are a losing operation, but they are critical for adoption. Tesla affords this via huge margins, but that won't work for the rest of the market outside of the luxury segment.

Could it be that the BEV market (in the US at least) lends itself to monopolization? If so, hydrogen can make sense as a technology that does not rely on losing charger network to operate (just like no car manufacturer needs to subsidize fuel stations).

Yes, batteries are in short supply. We have been increasing battery supplies, energy density, and reducing nickel and cobalt for a decade. Theres's basically endless demand today. I'm sorry but your comments are basically standard and inccurate fud against EVs.

Tesla already announced they were going to make their us charging network support the us ccs standard for charging. In Europe they have been rolling it out to all cars (that all use the same standard plug) for a few years. Tesla chargers in Europe that are already working for competitor cars are not ruinously expensive. The reason tesla got so much market share was their competitors are very threatened by the transition to a completely new drive train, making their billions of dollars in investments in design of ICE engines, but also the entirety of mufflers, alternators, emissions controls, spark plugs just worthless scrap over time. Of course they all wanted to keep doing something like an ice engine, Toyota wanted hydrogen, etc.

The Tesla network in Europe is compatible with everything else. All vendors are using CCS2. I know it's different in the US, but even there it seems to be changing.

The main advantage Tesla currently has is the size of the network as well as the seamless integration into their navigation system and automatic payment without a custom card. However this could be easily done by competitors if they would grasp the importance of it.

I am also wondering why I am forced to use random applications instead of having contactless interface for a debit card.

Counterpoint: I can't even refill my damn inkjet without the manufacturer doing their damnedest to get me to pay multiples for what's essentially commodity ink. I have no faith that hydrogen won't work the same.

There is little political will to regulate printer cartridges.

Cars on the other hand are heavily regulated.

The oil industry, I can assure you, would be quick to lobby for little standardization and regulation on hydrogen exactly for the reason they they want it to be in the same sorry state as printer ink

Don't you see even Tesla Supercharger is opening for all EVs? It won't work.

Yet those measures are being circumvented, because physically you can fill the cartridge, and legally, because this physical ability requires the manufacturer to take intrusive measures which are blocked by courts/legislators.

It's hard to force the consumer to not use their product. Conversely, it's hard to force the operator of a fast charger networks to do something. We can see other BEV manufacturer following Tesla's method (e.g. Rivian) setting up their own charger network. It's not a desirable future for such important market like transportation.

> misunderstandings about hydrogen technology as an energy source

The biggest misconception being that hydrogen is an energy source. We currently do not capture any hydrogen from nature. Almost all industrial hydrogen is currently derived from fossil fuels.