Energy balance of a continuous structural health monitoring system based on energy harvesting

The Structural Health Monitoring (SHM) may be a relevant technique to monitor historical buildings, masonry, bridges, etc. It becomes even more important if it can be applied in a continuous way, once incorporated in a Wireless Sensor Network (WSN), being able to provide data in an automatic and endless mode without any human intervention. Of course, WSN needs a power source, a role prevalently held by batteries. However, this solution has several issues: it is not eco-friendly and needs a periodic replacement hence increasing costs and reducing the SHM spread. The Energy Harvesting (EH) is a very promising technique to supply WSN. It converts the environmental energy into electrical energy allowing its local accumulation, within the sensor node, in supercapacitor or rechargeable batteries. Anthropic environments are plenty of energy (photovoltaic, kinetic, etc) but this is a non-continuous source and then an energy balance could highlight the suitability of an EH solution. This work is aimed to present a clear picture of EH for SHM by considering all the previous elements in the context of cultural heritage. The result is the definition of specific applications in which those WSNs, based on EH, could be competitive with respect to more traditional technologies.