I like what you've written, Ed. You and I actually have similar skeptical positions about hydrogen as an energy storage medium. But in the spirit of contrarianism, I'll give an argument from the other side. New developments could end up making both of us wrong.

The strongest argument against hydrogen for energy storage is the pathetic round-trip storage efficiency that it delivers. In theory, an electrolyzer-fuel cell combination should be capable of performance comparable to the 90% of a lithium-ion battery. In practice, as things stand today, 40% is about the most one can expect. And if the generation side uses modified combustion turbines rather than fuel cells, you can knock that down to 30 - 35%. That means, at best, 2.5 kWh of source generation for every kWh delivered from storage. That blows up the required size of the RE infrastructure that must be implemented. It blows up the resource requirements in materials extraction (non-renewable!), land use impact, and embedded carbon footprint by the same factor. It reduces the energy return on investment (EROI) below the point of viability.

The counterargument and caveat is that "in practice" is a moving target. With the intense investor interest and partisan support that the "green hydrogen" narrative has generated, surely it's only a matter of time before electrolysis and fuel cell advances close the gap between theory and practice?

That's a variation on the whispered "build it and they will come" trope from Field of Dreams. Throw enough subsidies at deployment and the magic of Wright's law will bring down the cost and improve the performance enough that subsidies will become unnecessary. Just look at what happened with solar panels and wind turbines!

Indeed, there are known ways to improve the efficiency of hydrogen production and power generation enough to raise the round-trip storage efficiency to at least 60%, and perhaps 70% or even more. High temperature steam electrolysis can lower the energy cost of hydrogen production by ~30%. And high temperature hydrogen solid oxide fuel cells, with waste heat feeding a high performance steam bottoming cycle, can deliver 80% efficiency on the generation side. The problem is that the specialized ceramic membranes required are expensive and degrade rapidly under use. Public and private R&D to develop stable membranes that still perform well has been ongoing for two decades, with little evident progress. But who knows? Never say never.