Heat pump system comprising: a first heat pump arrangement (101, 111) configured to operate with a first heat pump medium comprising CO2; a second heat pump arrangement (102, 114) configured to operate with a second heat pump medium comprising water, wherein the second heat pump arrangement comprises an input portion, an evaporator (120, 202), a liquefier (122, 306), and an output portion, the input portion being coupled to the evaporator (120, 202) of the second heat pump arrangement (102, 114), and the output portion being coupled to the liquefier (122, 306) of the second heat pump arrangement, wherein the second heat pump arrangement (102, 114) comprises a controller configured to control, as a function of a temperature (124a, 124b) prevailing at the input portion or of a temperature (124c, 124d) prevailing at the output portion, such that consumption of electric power by the second heat pump arrangement (102, 114) increases as the temperature (124a, 124b, 124c, 124d) prevailing at the input portion or at the output portion increases, and decreases as the temperature (124a-124d) prevailing at the input portion or the output portion decreases, and wherein the second heat pump arrangement (102, 114) comprises a turbocompressor having a radial impeller, a rotational speed of the radial impeller being controllable as a function of the temperature (124a-124d) prevailing at the input portion or of the temperature prevailing at the output portion; and a coupler for thermally coupling the first heat pump arrangement (101, 111) to the second heat pump arrangement (102, 114), said coupler (103, 115) comprising a first heat exchanger having a primary side and a secondary side, the secondary side of the first heat exchanger being coupled to the evaporator (120, 202, 320) of the second heat pump arrangement via the input portion, and the primary side of the first heat exchanger being coupled to the first heat pump arrangement, and said coupler (103, 115) comprising a second heat exchanger having a primary side and a secondary side, the secondary side of the second heat exchanger being coupled to the liquefier (122, 206, 306) of the second heat pump arrangement (102, 114) via the output portion, and the primary side of the second heat exchanger being coupled to the first heat pump arrangement (101, 111). a first heat pump arrangement (101, 111) configured to operate with a first heat pump medium comprising CO2; a second heat pump arrangement (102, 114) configured to operate with a second heat pump medium comprising water, wherein the second heat pump arrangement comprises an input portion, an evaporator (120, 202), a liquefier (122, 306), and an output portion, the input portion being coupled to the evaporator (120, 202) of the second heat pump arrangement (102, 114), and the output portion being coupled to the liquefier (122, 306) of the second heat pump arrangement, wherein the second heat pump arrangement (102, 114) comprises a controller configured to control, as a function of a temperature (124a, 124b) prevailing at the input portion or of a temperature (124c, 124d) prevailing at the output portion, such that consumption of electric power by the second heat pump arrangement (102, 114) increases as the temperature (124a, 124b, 124c, 124d) prevailing at the input portion or at the output portion increases, and decreases as the temperature (124a-124d) prevailing at the input portion or the output portion decreases, and wherein the second heat pump arrangement (102, 114) comprises a turbocompressor having a radial impeller, a rotational speed of the radial impeller being controllable as a function of the temperature (124a-124d) prevailing at the input portion or of the temperature prevailing at the output portion; and a coupler for thermally coupling the first heat pump arrangement (101, 111) to the second heat pump arrangement (102, 114), said coupler (103, 115) comprising a first heat exchanger having a primary side and a secondary side, the secondary side of the first heat exchanger being coupled to the evaporator (120, 202, 320) of the second heat pump arrangement via the input portion, and the primary side of the first heat exchanger being coupled to the first heat pump arrangement, and said coupler (103, 115) comprising a second heat exchanger having a primary side and a secondary side, the secondary side of the second heat exchanger being coupled to the liquefier (122, 206, 306) of the second heat pump arrangement (102, 114) via the output portion, and the primary side of the second heat exchanger being coupled to the first heat pump arrangement (101, 111).