The present invention relates to a method for regenerating 
heat energy with the aid of an 
energy system comprising n number of energy cells (121, . . . ,12n), wherein n is an integer, and n>2. The energy cells (121, . . . ,12n) are connected in sequence. Each energy 
cell (121, . . . ,12n) comprises a 
phase change material (PCM1, . . . ,PCMn), wherein PCMT1>PCMT2>, . . . , >PCMTn. The energy cells (121, . . . ,12n) performs the steps:to produce 
mechanical energy, which also causes rest 
heat energy (RH1, . . . ,RHn) stored in said energy 
cell (121, . . . ,12n) when the 
phase change material (PCM1, . . . ,PCMn) changes from 
solid phase to 
liquid phase; orto cool down when the 
phase change material (PCM1, . . . ,PCMn) changes from 
liquid phase to 
solid phase;to transfer said rest 
heat energy (RHx) from one energy 
cell (12x) which is 
cooling down as input energy to the next energy cell (12x+1), said method comprises the step:with the aid of a control means connected to said energy cells (121, . . . ,12n), to control said 
system alternately between a first phase, and a second phase, wherein, during said first phase, every two energy cells (121, 123, 125, . . . ) produces 
mechanical energy, and every two energy cells (122, 124, 126, . . . ) are 
cooling down, and vice versa during said second phase.