1. Safety concerns about hydrogen and oxygen in deep formations
“I realize there may not be an ideal oxygen mixture down there but wouldn’t there still be problems with using extreme heat in the presence of hydrogen??” – BobbyTables2
“I think there is literally no oxygen down there with the hydrogen… otherwise it would have slowly transformed into CO₂ over the eons without our help.” – ttul
2. Need for efficiency data on the electricity‑to‑hydrogen process
“OK, you put in electricity and get hydrogen. So where are the efficiency numbers?” – Animats
“Just using an electrolyzer to break up water is about 70% efficient, in terms of energy out / energy in.” – Animats
3. Geologic hydrogen generation via rock fracturing and natural reactions
“This company is using electrohydraulic fracturing to shatter ultramafic rocks and thereby increase the rate of natural geochemical processes… the actual source of the free energy… is partially reduced Fe(II) species… that can absorb an oxygen atom from water to produce free H₂.” – phenol
These three themes capture the main points of the discussion: safety implications, energy‑efficiency considerations, and the geological mechanism behind producing hydrogen from rocks.