Piezoelectric Energy Harvesting and Battery-Free LoRa Node for Sustainable IoT

Supplying energy to IoT sensors presents a critical challenge, not only due to the difficulty of providing power sources to devices but also because the ever-growing number of devices is leading to a significant increase in total energy consumption. Assuming that each sensor battery lasts 10 years, the current number of devices would lead to millions of daily battery replacements. In this paper, we present how replacing traditional batteries with capacitors in LoRa-Based Energy Autonomous Wireless Sensor Nodes (EAWSNs), enabled by energy harvesting systems, can create maintenance-free solutions suitable for deployment in remote areas. Our solution uses lead-free and non-toxic piezoelectric materials to power ultra-low-power LoRa nodes. The advantage of this lead-free technology is that it enables an "install-and-forget" approach for devices in practically any application where vibration energy is available, including industrial machinery, vehicles, and bridge monitoring. Experimental results show that with an acceleration of 0.7 g and a storage capacitor of 4 mF, the EAWSN can, on average, send LoRa packets every 471 seconds. By combining vibration energy harvesting with ultra-low-power LoRa nodes, we aim to pave the way for sustainable IoT ecosystems, minimizing environmental impact while ensuring reliable and autonomous operation of sensor nodes.