[ben_w]

Depends how expensive the electrolyser is. Just because I did make something when I was 9 years old that could fill up a small jamjar with hydrogen, doesn’t necessarily mean it’s economically viable.

(I have no idea either way if this is an important limit or not. Just that it can have other sources of downside besides merely using otherwise wasted energy).

[pfdietz]

There have been reports of cheap mediocre efficiency alkaline electrolyzers in China for under $200/kW. This is indeed a key area for hydrogen from intermittent renewables to be successful, but I think there's great room for cost decline here as volume ramps up.