A geothermal pile for harvesting electricity from a gradient of temperature between ambient air and an underground area is provided. The geothermal pile includes an elongated thermally-conductive body, a thermoelectric cell and an electrical output. The elongated thermally-conductive body has a first end and a second end opposite the first end. The second end is configured to be introduced, in use, into an underground area. The thermoelectric cell is provided at the first end so as to be exposed to ambient air when the second end is introduced into the underground area. The thermoelectric cell is in thermal contact with the second end of the elongated thermally-conductive body and is configured to generate electricity from a gradient of temperature between a first temperature of the ambient air and a second temperature of the underground area. The electrical output is electrically connected to the thermoelectric cell.