A power generator for use in a bore, the power generator comprising at least one drivable member; and at least one generation apparatus; the generation apparatus comprising at least one generator magnet for producing a magnetic field; and at least one electrically conductive member located or locatable within the magnetic field; wherein the drivable member is drivable by fluid flowing in the bore so as to produce relative motion of the at least one magnet and the at least one electrically conductive member in order to induce a current in the at least one electrically conductive member.