Energy Harvesting from the Natural Temperature Difference Between the Soil Surface and Soil Depth by Thermoelectric Generation

Abstract

Power generation from the natural temperature difference between the soil surface and soil depth was examined by comparing four different thermoelectric generator scenarios using ANSYS software. A 40-cm stainless steel heat pipe filled with water was used to transmit heat from the soil depth to the surface to run eight thermoelectric generator modules. 30 cm of the heat pipe was buried in the soil while the remaining 10 cm was kept above the earth’s surface to which the modules were attached. In the first scenario, no fins were added. In the second, aluminium fins were attached to the cold side of the modules and copper fins were attached to the lower end of the heat pipe. The third scenario differed from the second in that the surface area of the aluminium fins was increased ten times. The fourth scenario differed from the third in that the material of the heat pipe was copper. Results showed that the generated power in the first scenario was 169.68 microwatts which were increased 2.17, 4.7, and 5.85 times in the second, third, and fourth scenarios respectively. The findings suggest that such modules can be used in indoor and outdoor low-power applications.

Keywords

• thermoelectric generation; waste heat; soil thermal energy; heat transfer; generated power;