A method for liquefaction of a pre-processed natural gas to produce LNG, where pre-processed natural gas is introduced into a LNG heat exchanger where the pre-processed natural gas is liquefied by cooling against an evaporating primary refrigerant, where evaporated primary refrigerant is withdrawn from the LNG heat exchanger and re-liquefied by compression in a series of compressor steps, where the compressed gas from each compression step is cooled by means of heat exchangers, wherein an aqueous cooling medium cooled in an array of air coolers, is used for cooling of the primary refrigerant, is described.