> My unpopular opinion is that H2 is an overall very poor solution to our current problems.
I think you opinion is based on dated ideas. The interest in hydrogen is not being driven by electric cars, or as a battery replacement. It's being driven by one thing: if the price of renewable energy keeps dropping, it will be cheaper to make hydrogen than frac gas or mine coal. Even better, one accepted way to deal with renewables intermittency is to over provision. Over provisioning means we produce lots of unwanted electricity that is effectively free. If you can bottle what get get for free and sell it: profit.
To put this another way, the hydrogen will be used to produce heat. While lights, cars, planes and other things get all the attention, plain simple heating things is the number one user of energy. We use it to cook food, warm our houses, take showers, wash our plates and pants, iron our clothes, melt silicon ingots, make steel and concrete. Just about everything we use need heat in its production.
As you say storing hydrogen is problematic. As possible solution of storing it as anhydrous ammonia has been thwarted by our inability to reverse the reaction and get the hydrogen back. That little sticking point aside, it's nearly ideal. We efficiently produce enormous quantities of it now for fertilizer, and have decades of experience in ensuring your average job farmer handles this rather obnoxious substance safely.
But, where there is a lot of money to be made, people have an incentive to go looking. And in Australia at least it dawned there was a _lot_ of money to be made. Australia is the 5th largest exporter of natural gas in the world. Like ammonia natural gas is also difficult to handle. To transport methane efficiently it has to be a liquid, which is done by cooling it to -26O F and compressing 4psi. While exports are great now, it's on the nose. China, Australia's biggest customer, plans to be carbon neutral by 2060. But looming disaster could be circumvented as Australia has huge reserves of sunshine at it is mostly desert, it is politically stable and is very good at things requiring large coordinated infrastructure investment like food production and mining. Hydrogen would be a natural fit for us, if we could solve the storage problem.
So, they did. Or more precisely the scientific arm of the Australian government, CSIRO, did. They came us with a metal membrane that converts the ammonia back to hydrogen. https://www.csiro.au/en/Research/EF/Areas/Renewable-and-low-... I guess the plan is instead of taking delivery of a tank of methane, you take delivery of a tank of ammonia, and you convert it back to hydrogen and burn it.
Burning hydrogen sounds so low tech, so inefficient. It is low tech, but burning it for heat production is 100% efficient. And remember the driving force behind this is it will be cheaper than other things we burn, like coal and gas. This isn't rocket science. Anyone could do it, which is why Europe is looking at it too.