A fluid pump for moving a fluid from a first fluid source of the fluid in a low pressure state to a second fluid source of the fluid in a high pressure state, includes a chamber; a partitioning member displaceable in the chamber and dividing the chamber into first and second sub-chambers of varying volumes; the first sub-chamber having an opening controllably communicable with either the second fluid source or a third fluid source; the second sub-chamber having inlet and outlet openings controllably communicable with the first and second fluid sources, respectively; and a cooling element for cooling a fluid in the first sub-chamber.