In January 2021 the proof of concept was tested and with great success! We've got a green light (literally 😊 ).
To your left the inventor with the geothermal electricity generator (GeoTeg) before the underground installation. To your right the GeoTeg after installation, where just a small tower is visible housing the electronics, the generator and a heat sink.
When the temperature difference between the underground section and the surface section reached 6 degrees Celsius the small thermo-electric generator produced enough energy to power a small LED continuously.
The next steps in the development are increasing the efficiency of the components and increasing the power-output to a commercial viable level.