Utilizing Natural Thermal Gradients as Micro Energy Sources for Wireless Sensor Networks

The plethora of applications for Wireless Sensor Networks (WSNs) result in a wide range of environmental conditions for these networks. In many cases, the energy supply is the limiting factor for the lifetime of a network, as changing batteries is very hard or completely unfeasible. Energy harvesting is a very promising concept, as it allows to achieve a theoretically infinite network lifetime. Using Thermoelectric Generators (TEGs) to convert the thermal gradient between the upper soil layers and the ambient air promises energy supply in cases where other commonly used energy sources, such as solar cells, cannot be used due to lack of sunlight. We investigate the performance of a TEG harvester in a long-term experiment. Furthermore, we analyze the energy collected in relation to factors such as sunlight and season and show the feasibility of powering a WSN node from this power source.