Wearable energy harvesting from livestock: evaluation of different approaches

Smart agriculture relies on the application of numerous sensors for environmental monitoring, demanding sustainable energy sources to reduce battery replacements and fossil fuel dependence. As modern farms increasingly adopt Internet of Things (IoT) technologies for real-time tracking of animal health, soil conditions, and climate parameters, maintaining a consistent energy supply for distributed sensors becomes a major challenge. This study investigated low-voltage energy harvesting using a novel bell ring worn by livestock, incorporating piezoelectric, thermoelectric, electromagnetic, and photovoltaic methods. The concept enables continuous power generation from animal movement, body heat, magnetic field variation, and sunlight exposure, thereby minimizing maintenance needs and enhancing system autonomy. A circuit was designed to generate and store energy from these approaches. The voltage and power were measured over three days at different times of the day. Among the tested methods, photovoltaic energy generated the highest output, by 1052.01 mV and 283.77 μW, while piezoelectric energy had the lowest at 14.12 mV and 0.11 μW. The combination of all four methods, processed through a dc/dc converter, achieved a maximum outputs of 3103 mV and 2049 μW. These findings highlight the potential of multi-source energy harvesting for sustainable sensor operation in agriculture, supporting long-term monitoring and reducing energy waste.