Abstract: A method for obtaining useful energy from geothermal heat. A coaxial tube is provided which includes an inner and outer tube connected to together in an end section of the coaxial tube. The coaxial tube is introduced into a deep bore in the earth and a thermal medium liquid under standard conditions is introduced into the outer tube and flows in the direction of the end section of the coaxial tube. The thermal medium is heated while absorbing geothermal heat, passes through a phase transition in the region of the end section, passes over in gaseous form into the inner tube, and flows upward therein up to an upper end of the coaxial tube located at the Earth's surface. A flow generator for generating electric energy is operated using the flowing, gaseous thermal medium and the kinetic energy of the flowing gaseous thermal medium is converted to obtain usable energy.

Abstract: A device for controlling the temperature of a medium, comprising: a first circuit in which a first heating medium circulates without phase transitions; a second circuit in which a second gaseous heating medium circulates without phase transitions; a first heat converter arranged in the first circuit and in which the first medium exchanges heat with a surrounding medium: a second heat converter arranged in the first circuit and in which the first medium exchanges heat with the medium to be temperature-controlled; a first delivery means arranged in the first circuit for moving the first medium; a compressor arranged in the second circuit for compressing the second medium; a third heat converter arranged behind the compressor when seen in the flow direction so as to contact the second circuit and which exchanges heat with the first medium; and means for cooling or expanding the first medium.

Abstract: A device for controlling the temperature of a medium, comprising: a first circuit in which a first heating medium circulates without phase transitions; a second circuit in which a second gaseous heating medium circulates without phase transitions; a first heat converter arranged in the first circuit and in which the first medium exchanges heat with a surrounding medium: a second heat converter arranged in the first circuit and in which the first medium exchanges heat with the medium to be temperature-controlled; a first delivery means arranged in the first circuit for moving the first medium; a compressor arranged in the second circuit for compressing the second medium; a third heat converter arranged behind the compressor when seen in the flow direction so as to contact the second circuit and which exchanges heat with the first medium; and means for cooling or expanding the first medium.