A generator comprising: - a heat differential module comprising at least: ∘ a first, high temperature reservoir configured for containing a work medium at high temperature; ∘ a second, low temperature reservoir configured for containing a work medium at low temperature; and ∘ a heat mechanism being in fluid communication with at least one of the reservoirs and configured for maintaining a temperature difference therebetween by at least one of the following: ▪ providing heat into said first, high temperature reservoir; and ▪ removing heat from said second, low temperature reservoir; - a pressure module comprising a pressure medium which is in selective fluid communication with said first, high temperature reservoir and said second, low temperature reservoir of the heat differential module for alternately performing a heat exchange process with the high/low temperature work medium of the reservoirs, to fluctuate between a minimal operative temperature and a maximal operative temperature of the pressure medium corresponding to the high and low temperature of the reservoirs; - a conversion module being in mechanical communication with said pressure medium and configured for utilizing temperature changes of the pressure medium for the production of output energy; and - a heat recovery arrangement being in thermal communication with said heat differential module and configured for absorbing heat from the pressure medium and providing heat to the heat differential module or to the pressure module; and - at least one temperature gradient tank being in fluid communication with an outlet end of said pressure module and being configured for maintaining a temperature difference between at least two work medium quantities simultaneously contained therein. - a heat differential module comprising at least: ∘ a first, high temperature reservoir configured for containing a work medium at high temperature; ∘ a second, low temperature reservoir configured for containing a work medium at low temperature; and ∘ a heat mechanism being in fluid communication with at least one of the reservoirs and configured for maintaining a temperature difference therebetween by at least one of the following: ▪ providing heat into said first, high temperature reservoir; and ▪ removing heat from said second, low temperature reservoir; ∘ a first, high temperature reservoir configured for containing a work medium at high temperature; ∘ a second, low temperature reservoir configured for containing a work medium at low temperature; and ∘ a heat mechanism being in fluid communication with at least one of the reservoirs and configured for maintaining a temperature difference therebetween by at least one of the following: ▪ providing heat into said first, high temperature reservoir; and ▪ removing heat from said second, low temperature reservoir; ▪ providing heat into said first, high temperature reservoir; and ▪ removing heat from said second, low temperature reservoir; - a pressure module comprising a pressure medium which is in selective fluid communication with said first, high temperature reservoir and said second, low temperature reservoir of the heat differential module for alternately performing a heat exchange process with the high/low temperature work medium of the reservoirs, to fluctuate between a minimal operative temperature and a maximal operative temperature of the pressure medium corresponding to the high and low temperature of the reservoirs; - a conversion module being in mechanical communication with said pressure medium and configured for utilizing temperature changes of the pressure medium for the production of output energy; and - a heat recovery arrangement being in thermal communication with said heat differential module and configured for absorbing heat from the pressure medium and providing heat to the heat differential module or to the pressure module; and - at least one temperature gradient tank being in fluid communication with an outlet end of said pressure module and being configured for maintaining a temperature difference between at least two work medium quantities simultaneously contained therein.