Internet of Natural Things (IoNT): An Experimental Evaluation of Best Position to Harvest Thermal Energy from Trees

The Internet of Things (IoT) is a technology concept where everyday objects feature connectivity to the Internet based on embedded devices that need some energy source for their operation. IoT devices present issues related to energy efficiency and energy self-sustainability. In a particular application of IoT, called Internet of Natural Things (IoNT), natural objects such as trees, fruits, birds, mammals etc. can send data to Internet. An interesting application of IoNT is the Smart Tree, which consists of harvesting thermal energy from a tree to feed embedded wireless sensors located at the tree itself. Considering the Smart Tree application, this work describes an experimental evaluation of thermal measurements from different points (heights, depths, and directions) of a tree trunk to obtain the best position to harvest energy from trees. For this, a sensor node has been developed to measure thermal gradient (external temperature and the internal temperature difference) of tree trunk points in real-time. From the obtained results, it has been possible to conclude that the highest temperature gradient occur at 2 m height (50% of tree height, that is, the central point of the tree trunk) and at 3 m height (75% of tree height) from 9 AM to 5 PM to the West direction. So, these positions are considered the best ones to harvest thermal energy in the west-southern hemisphere.