Energy harvesting in precision agriculture applications (ENTRAP) was a Marie Skłodowska Curie Action individual fellowship awarded to David Blažević and Tampere University. The aim was to develop a small wearable device which can convert the natural motion of farm animals into electrical power. In the precision agriculture management concept, or more specifically precision livestock farming, smart wearable devices are being used to manage livestock production. Farm animals can be equipped with special smart collars, leg straps or ear tags with embedded health or wellbeing monitoring sensors (temperature, disease, geolocation etc.). These smart wearables report the animal’s health status or location wirelessly to the farmer. Millions of smart farming devices are being marketed today in the EU and all are powered with batteries with limited capacity (finite lifetime batteries). Battery manufacturing is known to be unsustainable and a toxic polluting practice with low recycling rates which produces negative effects on the ecosystem. Thus, the goal of project ENTRAP was to replace batteries in these wearable devices with a small electromechanical generator. The generators use a moving permanent magnet mechanism which reacts to simple animal movement like a cow’s step or ear flap and – based on Faraday’s principle of electromagnetic induction– converts that kinetic energy into electrical energy by inducing voltage in a coil. To design such a generator animal locomotion was first measured and analyzed and then a numerical model was developed which could take recorded animal movement as an input. Computer simulations were performed and based on the results, laboratory prototypes were built and tested on field with free grazing cattle. The conclusive result of action ENTRAP is that certain low power smart farming devices could be completely powered by animal locomotion. For more energy intensive applications, like virtual fencing, significant increases in battery lifetimes could be achieved. The action has also shown that these generators could be made cheap, reliable, and easily integrated with existing smart farming devices.
