Collector and use thereof

A polymer geothermal collector for extracting geothermal energy from a well, the polymer geothermal collector being configured to be placed in the well for enabling circulation of a fluid in the polymer geothermal collector, when placed in the well, for performing heat exchange between the fluid in the polymer geothermal collector and the well, the polymer geothermal collector comprising a first portion for transporting the fluid into the well and a second portion for transporting the fluid out from the well, wherein:

• the first and second portions of the polymer geothermal collector each have an elliptical cross-section, having a first cross-sectional distance having a first length and a second cross-sectional distance having a second length, in a plane perpendicular to a length extension of the polymer geothermal collector, and wherein the second length is at least 1.2 times the first length,
• a wall of each of the first and second portions of the polymer geothermal collector has a wall thickness in the interval 0.02-0.06 times a sum of the first and second lengths, and is configured to be supported by the fluid for circulation in the polymer geothermal collector, wherein the fluid has a density above 1.1 g/cm3 for supporting the walls of the first and second portions of the polymer geothermal collector, when the polymer geothermal collector has been installed in the well,
• outer surfaces of the elliptical cross-sections of the first and second portions of the polymer geothermal collector can be placed touching each other and simultaneously touching a circular footprint, and
• a combined cross-sectional area of the first and second portions of the polymer geothermal collector is at least 0.6 times an area of the circular footprint, when the elliptical cross-sections of the first and second portions of the polymer geothermal collector are placed touching each other and simultaneously touching the circular footprint.