You can get green hydrogen via electrolysis using power from green sources such as wind and solar. I don't thinknits practical to do via heat at all. Though not much hydrogen is produced like this most coming from 'blue' and 'grey' sources which are just greenwashing attempts from fossil fuel companies.

Agreed. But in cases where a large amount of energy is needed on one tank/charge (large freight haulers, long-distance busses, trains, etc.) hydrogen might be a good alternative to petrol while we work on improving battery capacity and recharge times.

You're never going to see 95% efficiency doing that. You'll realistically lose around 20% or so from things like parasitic losses, AC-DC conversions, transmission losses, etc. And that's ignoring the energy needed to make the battery in the first.

Unfortunately this isn’t even a solvable problem. The fundamental limit of efficiency due hydrogen to electricity is about 50%. Physics and entropy prevent it from being any higher.

That's completely wrong. An electrolyzer is an electrochemical system. It has about the same level of efficiency as charging a battery. People are just regurgigating BEV propaganda here.

In reality, hydrogen is far more scalable than batteries. What people don't realize is that you will fail to capture all of your renewable energy with batteries. You end up with a lot of curtailed power. You actually have to use hydrogen for this, and in fact you'll have fewer solar panels in the long run.