Hydrogen is basically just a really inefficient battery. Nice if you really need it for e.g. energy density reasons but basically sub-optimal for other things.
The challenge with hydrogen hydrogen is energy losses in producing it are about 3-4x (so use 4 kwh of electricity to produce 1kwh of hydrogen). And then you lose more actually burning it. And storing and transporting it add to those losses. Using the electricity directly for heating the iron/steel is much more efficient and potentially a lot more cost effective since you effectively use at least 3-4x less MWH. That's a lot of cost savings. And those can finance a lot of batteries and other solutions.
Hydrogen is directly useful in electrical synthethis of methane and ammonia, besides myriad current industrial uses, and, as LH2, is disruptive as an aviation fuel: LH2 aircraft will be impossible to compete with, wherever they are available.
Low density is also a big reason why using LH2 in the first stage of a rocket launch vehicle is a dumb idea.
In the meantime, we will need synthetic hydrocarbons, using captured carbon, for extant airframes. It will need to get (or be made, through carbon taxes) cheaper than the mined, refined, and transported stuff.
Having a big hydrogen synthesis infrastructure in place feeding hydrocarbon synthesis will then ease the transition off of hydrocarbons, as equipment that can use hydrogen directly comes online. Stationary uses will come first, displacing natural gas electric generation.
Instead these are advertisements for "blue" hydrogen-- cracking natural gas and then injecting the CO2 back into the ground. It's a campaign by fossil fuel companies to preserve some of the value of their capital base, rather than just being shut down entirely. Blue hydrogen will be a lot cheaper, at the cost of fossil emissions from methane and CO2 that escape from the equipment or leak from the wellhead.
So it's basically just good old fashioned lies.
And it has a tendency to leak through most materials.
https://planetforlife.com/h2/h2swiss.html#:~:text=Hydrogen%2....
"B&E estimates that a liquid hydrogen tank designed for automobile use will loose about 5% of its capacity every day, which is to say that all of it will be gone in 20 days. Losses of this magnitude are acceptable for, say, a taxicab fleet, but unacceptable to most people."
Also new to me that it's a greenhouse gas: "Hydrogen cannot be vented to the atmosphere because it is an explosion hazard and because it is a greenhouse gas. The vented hydrogen must be burned. A continuously running gas stove with one burner set to "medium" would do it."
The world uses many millions of tons of hydrogen a year. There are already 1600 miles of hydrogen pipeline in the US. So, while materials must be chosen carefully, materials compatible with hydrogen obviously exist.
Transportation is not the only, or even a particularly favorable, use case for hydrogen. Pointing to it to paint all hydrogen uses as inadvisable is not honest, especially in a thread where we're talking about reduction of iron ore, not cars.
Hydrogen is a greenhouse gas in this sense: hydrogen consumes OH radicals in the atmosphere which would otherwise go to destroying methane. So, indirectly, hydrogen causes warming by reducing destruction of methane. The effect is not large, however. Carbon monoxide has a similar indirect effect.
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1534664
>Bench scale experiments made use of an externally heated reactor while pilot scale experiments conducted under this grant used a reactor that was self-heating.
>At the bench scale, oxygen was produced with minimal corrosion of the anode material. At the pilot scale experiments in the self-heated reactor were not able to demonstrate oxygen production at the anode, or the production of iron as measured by tracer dilution. Further work is necessary to elucidate the difference between bench and pilot scale results.
https://www.rechargenews.com/energy-transition/will-us-and-e...
https://investors.linde.com/archive/praxair/news/2007/praxai...