There’s two problems with your last post which have to do with physics.

1. Fuel Cells and the process of hydrolysis have a limit on their efficiency. Just like with ICEs there isn’t much potential there.
2. Between Hydrolysis and the Fuel Cell, there are other lossy processes. Usually the tanks contain pressurized H2 and depending on the usecase even liquid H2. Modern automobile cases use 700-800 bars of pressure. That process is again at around 85% efficiency in a good case. Cooling applications further deteriorate the efficiency and need more energy for storage and/or losses during storage. There are other technologies in research right now, like metal hydride storage, where we’ll have to see what exactly they can do (right now we’re at the stage where we are promised an all-purpose hype, but mostly through the media and not the ones doing the work)

I’m not disputing that capitalism has it’s thumb on the scale; as you’ve written, the synergy to use H2 derived from natural gas is one effect, but it doesn’t stop them from advertising it as green. The physical limits though, one cannot argue with. Their effects would mean a lot more infrastructure that is necessary, with it more materials, which are limited too. Even if possible, we have limited construction capacity, which means that it would take us longer to reach the goal, when time is of the essence. Which leads me to the same conclusion, that where the advantages like power density isn’t absolutely necessary or other solutions are not available, use a better solution.

It is not only economic cost though. As I’ve mentioned, materials are also limited (on the same level as: There isn’t enough copper to wire all motors needed to replace all cars today with EVs). And it needs alot of surface area compared to the concentrated power plants of the past, which means an even bigger impact on the biosphere (especially if not done on rooftops in cities but in mountain ranges or fields, etc.). Don’t get me wrong; solar energy, if done right, is the only source that doesn’t interfere with natural cycles and does not increase entropy of the planet (which makes it actually sustainable). Using it inefficiently though, means inefficient use of other resources which are limited. (Not only economic. But on that note: Public infrastructure is always built with costs in mind, because we shouldn’t waste tax money, so we can do a better and more comprehensive job with what we have.)

So if there is a more efficient way to store energy for long periods, then it should take precedence over a very inefficient one. This will get complex since it is very much dependent on the local conditions such as sunshine, water sources and precipitation, landscape, temperatures, grid infrastructure and much more. As an engineer, I would throw in though, that if you need this secondary storage, that is not much cheaper, doesn’t have some very essential advantage, or doesn’t mitigate some specific risk, but is much more inefficient over your primary storage, then the system’s design is… sub-optimal to put it mildly.

For the argument of exploring everything: We simply can’t. More precisely we could, but it would need much more time, money and resources to arrive at the goal. And since climate catastrophe is already upon us, we don’t have that time and need to prioritize. Therefore a technology that has a physical, not human-made, efficiency limit loses priority as a main solution. That doesn’t mean, that H2 should not be looked into (for specific purposes, where it is essential or the reuse of existing infrastructure is the better option), but that we have to prioritize different avenues, with which we can take faster strides towards true carbon neutrality.

P.S. it doesn’t help, that today’s H2 is almost exclusively derived from natural gas.

I agree that H2 can have certain applications as a bridge technology in some industries, but there is a very important parameter missing in your premise.

Even if solar power seems “free” at first glance it really isn’t. It needs infrastructure, e.g. Photovoltaic Panels and lots of it. So just having H2 instead of a battery for an application means, it needs thrice the PV capacity or even more and with it the grid capacity. Now add to that, we aren’t just talking about replacing electricity from fossil fuel plants by PV, but about primary energy as a whole, which makes the endeavor even more massive. Also H2 will not magically become much more energetically efficient in its production, transport, storage and usage, because there are physical limits. (Maybe with bacteria for production) The tech could and should get better concerning longevity of the electrodes for example. Also as the smallest molecule out there, storage will never be completely without losses. And long term storage requires even more energy and/or material.

All this is to say, that efficiency is still paramount to future energy supply, since also the material is limited or just simply because of costs of infrastructure and its implications on the biosphere. Therefore such inefficient energy carriers as H2 or what people call “e-fuels” should be used only where the enormous power and/or energy density is critical. H2 cars should therefore never be a thing. H2 or e-fuel planes, construction machines or tractors on the other hand could be more appropriate uses.