Abstract: A process for the liquefaction of natural gas having a pressure above atmospheric pressure, is disclosed in which a feed gas is cooled to sequentially lower temperatures, by passing the gas through a plurality of cooling stages, in heat exchange with at least three refrigerants, until the gas is substantially completely condensed in the last of the cooling stages. The pressure of the feed gas is reduced to near atmospheric pressure during the cooling of the feed gas by the use of hydraulic expanders which extract work during pressure reduction. Additionally, pressure reduction of the refrigerants within the refrigerant cycles is performed by similar hydraulic expanders. The work extracted by said hydraulic expanders is used to provide power to the liquefaction process, such as by helping to power compressors or pumps used in the liquefaction process.