Heat exchanger with - a first and a second temperature controllable structure (21, 22), which are arranged to each other with a distance such that during heating or cooling of the two temperature controllable structures (21, 22) an intermediate area is formed between them, which has a different temperature than the two temperature controllable structures (21, 22); - a heat conductive element being in heat contact with the first and the second temperature controllable structure (21, 22) for discharging or supplying heat from or to the first and the second temperature controllable structure (21, 22), wherein the heat conducting element comprises - a first, second and third section (31, 33, 35) of an electrical conductive material, characterized in that - the first and the second section (31, 33) are connected to each other via a first connecting element of a first thermoelectric material and the second and the third sections (33, 35) are connected to each other via a second connecting element of a second thermoelectric material, which is different from the first thermoelectric material, and wherein - a first side of the first connecting element of the first temperature controllable structure and a second side of the first connecting element face the intermediate region, - a first side of the second connecting element of the second temperature controllable structure and a second side of the second connecting element face the intermediate region, - the second section of the heat conducting element is connected on the one hand to the first side of the first connecting element and on the other hand to the first side of the second connecting element, - such that the first sides (321, 341) of the connecting elements (32, 34) are in each case exposed to another temperature than the second sides (322, 342), if the first and the second temperature controllable structures (21, 22) are also heated or cooled and the heat conducting element according to the type of the thermal generator generates an electrical voltage, - a first and a second temperature controllable structure (21, 22), which are arranged to each other with a distance such that during heating or cooling of the two temperature controllable structures (21, 22) an intermediate area is formed between them, which has a different temperature than the two temperature controllable structures (21, 22); - a heat conductive element being in heat contact with the first and the second temperature controllable structure (21, 22) for discharging or supplying heat from or to the first and the second temperature controllable structure (21, 22), wherein the heat conducting element comprises - a first, second and third section (31, 33, 35) of an electrical conductive material, characterized in that - the first and the second section (31, 33) are connected to each other via a first connecting element of a first thermoelectric material and the second and the third sections (33, 35) are connected to each other via a second connecting element of a second thermoelectric material, which is different from the first thermoelectric material, and wherein - a first side of the first connecting element of the first temperature controllable structure and a second side of the first connecting element face the intermediate region, - a first side of the second connecting element of the second temperature controllable structure and a second side of the second connecting element face the intermediate region, - the second section of the heat conducting element is connected on the one hand to the first side of the first connecting element and on the other hand to the first side of the second connecting element, - such that the first sides (321, 341) of the connecting elements (32, 34) are in each case exposed to another temperature than the second sides (322, 342), if the first and the second temperature controllable structures (21, 22) are also heated or cooled and the heat conducting element according to the type of the thermal generator generates an electrical voltage,