| CPC F28D 20/0052 (2013.01) | 15 Claims |

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1. An arrangement for storing thermal energy, the arrangement comprising
a circuit containing a working fluid, the circuit having a plurality of pipes which pipes are distributed throughout a volume of the ground forming a heat storage, each pipe being arranged in a channel in the ground for heat exchange between the working fluid and the ground, and
an electrical heating element, the electrical heating element being arranged in a channel in the ground to heat the ground for storing thermal energy in the heat storage, wherein the working fluid is a liquid having a boiling point above 120° C. at atmospheric pressure.
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