NOVELTY - The method comprises providing a working medium containing an organic compound as a refrigerant, where the working medium is circulated by a borehole brought down to the earth, and is heated and vaporized within the borehole by a geothermal energy or a terrestrial heat. The working medium is made to flow with a central downpipe (32) of a pipe string (30) and a riser pipe (34) that surrounds the downpipe and is communicated with the downpipe at a lower end of the borehole. The working medium flows in a liquid form through the downpipe.    USE - The method is useful for generating an electric power from a geothermal energy or a terrestrial heat (claimed).    ADVANTAGE - The method ensures rapid and economical generation of the electric power from the geothermal energy or the terrestrial heat in an efficient manner.    DETAILED DESCRIPTION - The method comprises providing a working medium containing an organic compound as a refrigerant, where the working medium is circulated by a borehole brought down to the earth, and is heated and vaporized within the borehole by a geothermal energy or a terrestrial heat. The working medium is made to flow with a central downpipe (32) of a pipe string (30) and a riser pipe (34) that surrounds the downpipe and is communicated with the downpipe at a lower end of the borehole. The working medium flows in a liquid form through the downpipe, from which it reaches the riser pipe at the lower end of the borehole. The working medium is heated and vaporized after entering the riser pipe, during rising, by a lower portion of the riser pipe with a high heat conductivity, and is isothermally conducted by an upper portion of the riser pipe with a low thermal conductivity. The circulation of the working medium is effected or aided by a circuit (14) through a difference between a hydrostatic pressure of the liquid working medium in the downpipe and a pressure of the vaporized working medium in the riser pipe. The heated and vaporized working medium is relaxed after discharge from the borehole by performing a work in an expansion machine, or is delivered in a heat exchanger to other working medium, which is heated and vaporized in the heat exchanger and then is relaxed by performing the work in the expansion machine. An INDEPENDENT CLAIM is included for a plant for generating an electric power from a geothermal energy or a terrestrial heat.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic view of a plant for generating an electric power from a geothermal energy or a terrestrial heat.    Circuit (14)    Wellhead (18)    Pipe string (30)    Downpipe (32)    Riser pipe. (34)