I hear a lot about replacing gas with hydrogen (completely doable with the existing infrastructure).
If that's anything resembling correct...then the change-over would be more like replacing all-diesel fuel & engine infrastructure with gasoline.
Hydrogen can be cheap (extracted from natural gas) or green (electrolysis). It can't be both.
Hydrogen is also a monumental PITA to store.
As for storage, it's true that storing hydrogen is problematic but once I calculated that even existing facilities for natural gas in, say, Germany would be sufficient for a whole month of the whole country's grid running off of hydrogen. This is less than the several months provided by using the same storage for natural gas, but since in the following decades, the demand for this gas is going to shrink severely as German buildings are going to be replaced by low-energy buildings (pursuant to the 2010/31/EU Energy Performance of Buildings Directive and the 2012/27/EU Energy Efficiency Directive, as well as presumably future regulations), this capacity might be freed up, and in any case it's a much larger capacity than is predicted to be required (https://www.sciencedirect.com/science/article/pii/S001429211...) for a 100% renewable grid in Germany.
One interesting idea I don't know the feasibility of but is tempting anyway is ultra-large-scale liquid hydrogen storage. Considering the square-cube law and low density of liquid hydrogen stressing the structure (just 70 kg per cubic metre of liquid hydrogen tank, as opposed to 1000 kg per cubic metre of a water tank, for example), ultra-large-scale storage of hydrogen could be feasible in principle -- certainly much more than for example liquid hydrogen storage for a car, and in industrial settings to boot (as opposed to cars handled by ordinary citizens).
As I understood it natgas storage facilities wouldnt keep hydrogen. It'd leak.
But green hydrogen is only useful if electricity is cheap but batteries are expensive. The original article indicates why batteries aren't expensive and are likely to get dramatically cheaper over the next decade. That's why hydrogen is likely to stay irrelevant except for niche use cases.
e.g. steel manufacturing can use Green Hydrogen for the Reduction reaction, as part of the alternate pathway without coal.
That is absolutely not true. How exactly will cheap batteries for example allow you to make ammonia for agriculture, the chemical industry, etc.? Current global ammonia production alone is worth something like two hundred gigawatts of power continuously pumped into electrolyzers. That's like ten percent of global electric generation at the moment.
Hydrogen from electrolysis is best viewed as an intermediate feedstock for further chemical synthesis, as with ammonia production, methane production, jet fuel production, etc. There is perhaps potential for dumping excess grid electricity into hydrogen storage tanks at power plants as a temporary storage system, i.e. converting the hydrogen back to electricity via fuels cells (not turbines!) to meet electrical demand later.
Hydrogen storage requires special alloys to avoid steel embrittlement however, so it's fairly expensive.