Ask HN: Most efficient apparatus in kWh/liter to extract water from atmosphere?

An overly broad question but would would something like https://www.nature.com/articles/s41598-022-24314-2 ("Increasing freshwater supply to sustainably address global water security at scale") be of interest/relevant?

Both https://en.m.wikipedia.org/wiki/Air_well_(condenser) and Fog Nets can be entirely passive, requiring no input of energy.

Rain water tank?