[electronW1zard]

The issue the top level comment was pointing out was the use of hydrogen in its form as an elemental gas (H2). Not the use of hydrogen in chemical compounds. Already chemical production plants that use elemental hydrogen as part of their processes have to take into account its issues with causing metal embrittlement and that it can escape pressure containers through diffusion.

If you have a hydrogen energy supply chain and are storing hydrogen in vehicles, service stations and a lot of other infrastructure, escaped hydrogen may start causing structural issues in structures that were never designed with hydrogen storage in mind. If we transition to hydrogen powered cars, parking garages may have to be redesigned to handle metal embrittlement caused by accumulated hydrogen leaks from vehicles.

[pfdietz]

Ammonia is synthesized using hydrogen gas. Yes, the final product is not hydrogen, but hydrogen is an essential feedstock.

All this pearl clutching about hydrogen embrittlement ignores that industry solved this problem a century or more ago. It's a consideration that must be taken into account when selecting materials, not some sort of all powerful showstopper.

To be clear, none of what I'm saying should be taken as an endorsement of hydrogen as a fuel for automobiles.

[pama]

I worked in materials science in the past. Although I dont recall all details, I have seen seen convincing presentations from researchers at the Weizman institute claiming strongly we are far from ready for a transition to a hydrogen economy, and I have seen no evidence or supporting studies since then arguing that we know how to introduce hydrogen cars to steel cities. We wont have ammonia synthesizers in every street of Manhattan, yet we have plenty of buildings that might start failing fast if people replaced their parked cars with hydrogen cars. I do think it would be cool if the structural part of the world was different and would allow for such cars to roam the streets, but the US is not loving rebuilding physical structures for the purpose of a new technology, so I think it will take a while, and a couple accidents to get things right at a slower pace. We might never need H-cars in the end.

[pfdietz]

Sure. But this isn't because of embrittlement, it's because of other issues: lower round trip efficiency than batteries, difficulty of storing hydrogen in a vehicle, and the cost of fuel cells.