Abstract: A method and system for increasing the pressure of gaseous fuel delivered to a fuel system of a gas turbine engine. A portion of pressurized gas or compressed air is discharged from a high-pressure section of the gas turbine engine and is communicated to a plurality of radial inflow turbines or axial flow turbines. Energy is transferred from each turbine to a plurality of compressors driven by the turbines. Gaseous fuel is supplied to an inlet of one of the compressors. The compressed gaseous fuel is then cooled downstream of the compressors. The aftercooled and compressed gaseous fuel is delivered to the fuel system of the gas turbine engine.