Method and apparatus for cooling a hydrocarbon stream (520) to produce an at least partially liquefied hydrocarbon stream (530). A cooled main refrigerant stream (245) is further cooled against at least a part of one or more expanded cooled pre-cooling refrigerant streams (155). A hydrocarbon stream (520) is at least partially liquefied in one or more main heat exchangers (220) against an expanded cooled main refrigerant stream (255), to provide an at least partially, preferably fully, liquefied hydrocarbon stream (530). The air inlet stream (45) of a first gas turbine (50) is cooled using cooling duty from the main refrigerant in the main refrigerant circuit (200) to provide a cooled air inlet stream (55) to the first gas turbine (50).