A method of efficient cold recovery from a liquid hydrogen stream includes warming a cold liquid hydrogen stream by indirect heat exchange with a cold feed air stream in an ASU sub-cooler, thereby producing a warmed liquid hydrogen stream. Wherein at least a portion of the cool inlet air stream is introduced into a cold booster, thereby producing the compressed cool feed air stream. Wherein at least a first portion of the further cooled feed air stream is introduced into an expander, thereby producing an expanded feed air stream. Wherein a second portion of the further cooled feed air stream is further cooled, thereby producing the cold feed air stream. And, wherein the liquid oxygen stream has a first molar mass flow rate, and the cold liquid hydrogen stream has a second molar flow rate that is between 1.5 and 2.5 times the first molar mass flow rate.

A portion of feed air is expanded and cooled in front of a main heat exchanger, and is used as cold for precooling the remaining unexpanded feed air inside the main heat exchanger. A portion of the feed air precooled inside the main heat exchanger is removed to outside the main heat exchanger, expanded and cooled, and used as cold to cool the remaining unexpanded precooled feed air inside the main heat exchanger.

A portion of feed air is expanded and cooled in front of a main heat exchanger, and is used as cold for precooling the remaining unexpanded feed air inside the main heat exchanger. A portion of the feed air precooled inside the main heat exchanger is removed to outside the main heat exchanger, expanded and cooled, and used as cold to cool the remaining unexpanded precooled feed air inside the main heat exchanger.