A generator comprising: a heat differential module with a first, high temperature source configured for providing a work medium at high temperature, a second, low temperature source configured for providing a work medium at low temperature, and a heat mechanism in fluid communication with the first and second sources, configured for maintaining a temperature difference therebetween by at least one of: providing heat to the work medium at said first source, and removing heat from the work medium at said second source; a pressure module comprising a pressure medium which is in selective fluid communication with the work medium from the first, high temperature source and the work medium from the second, low temperature source, for alternately peifonning a heat exchange process with the high/low temperature work medium, to have its temperature fluctuate between a rmnimal operative temperature and a maximal operative temperature corresponding to the high and low temperature of the respective work medium; a conversion module in mechanical communication with the pressure medium, configured for utilizing temperature fluctuation of the pressure medium for the production of output energy; and a heat recovery arrangement in thermal communication with at least one of the heat differential module and the pressure module, configured for receiving at least a portion of the heat energy of the high and low temperature work medium which was not transferred to the pressure medium during said heat exchange process, and redirecting said heat energy back to one of the heat differential module and the pressure module; wherein provision of heat to the work medium is performed by way of a heat exchange process with an auxiliary high temperature fluid.