Energy Harvesting for Health Monitoring Balises : Analytical study

Sammanfattning: Balises are transponders installed in railways. These devices are nowadays powered by means of a radiofrequency signal emitted by each running train that passes above them. It is only during this moment that the health state of the balises is checked. Hence, there is currently no way to check whether the balises are properly working before the train passes by them. With the aim of executing regular health checks to the balises, an additional source of energy to monitor the balises should be contemplated. Energy harvesting is observed as a suitable solution for this issue. However, a lack of suitability studies is contemplated which englobes the available energy harvesting solutions in railway environments. Therefore, this thesis presents an exploratory work that uses the health monitoring of the balises as a test case for the study of the compatibility of different energy harvesters in diverse railway environments. Hazardous and remote areas are identified as locations of interest for the implementation of the technology, as cabling in those areas is costly and health checks to balises that are not constantly active are of outmost interest. Thus, the addition of wireless communication networks is also studied, due to the need of sending the information obtained in the health checks to monitoring control units. After an initial research study is performed, requirements in railway environments are defined, and three railway scenarios are selected for a suitability study. Then, the investigated energy harvesters and wireless communication networks are compared analytically, and possible technologies for the storage of the harvested energy are presented. It is found that no energy harvester exists that suits all the environments and shows a sufficient power output to make constant checks in remote areas. Nonetheless, piezoelectric and wind harvesters are proposed, because of the commercial availability of the former and the potential of the latter. In terms of wireless communication networks, LoRaWAN shows a low power consumption, while it offers a wide communication range and global coverage. It is, therefore, proposed as the best framework for the wireless communication networks.