Tbh i started talking before i read the article, so no clue about the working temperature. There are multiple concepts floating around afaik - using air/gas is neat because it wont freeze, some liquids might be more efficient but require more maintenance and have higher leaking risks... The one i saw a vid on was working with very cold gas that would get heated to maybe 30-50, would then be cooled via heatpump and repeat. Guess it makes sense to both send the medium cold so it doesnt heat too much, and have pipes that can handle heat (they would need to manage max heat if at any moment the system cant pump)

But: dunno, still didnt read on this one. The concept itself is 100% sound and worthwhile imo, but the question of HOW will have to be solved by engineers.

Most likely multiple paths that work in different conditions.