Many environmental and wildlife monitoring sensors need sustainable power supplies capable of providing low-voltage energy across multiple years of service life with a minimum requirement for maintenance and a minimal impact on the environment. This is an idealized representation of one such technology tested in an arboreal bird monitoring station, the actual device appeared as little more than a closed PVC pipe painted in green and brown with vegetation glued to its exterior to reduce potential impact on the local environment.
This design was meant to derive electricity through several mechanisms, including a mobile permanent magnet that oscillated within three conductive coils as well as a piezoelectric film applied to the suspensory spring mounting. A flexible thin-film photovoltaic solar panel was wrapped around the experimental device’s body, with a monocrystalline PV solar cell atop it. The thin-film PV panel was scavenged from a damaged wildlife feeder and afforded a series of loose strips of PV material in addition to the section wrapped around the experimental body. I attached these to a common feed and allowed them to dangle from the device as a loose shroud.
In testing the energy production potential, I found that although the oscillating magnet was able to generate a harvestable current in the coils, the piezoelectric film had too high a resistance to provide a usable current after rectification. It is possible that direct vapor deposition onto a conductive flexible material with a second conductive layer deposited atop this might provide a more effective solution for piezoelectric power generation. By far, the photovoltaic materials out-performed the vibrational energy harvesting components – so for an outdoor installation PV solar would be the better solution for sensors located in un-obscuring foliage above ground.
Much was learned from the study of this design, and it demonstrated the potential for power generation through simple oscillating movement and vibration. This could be adapted to power long-cycle sensors for atmospheric, underground and submerged environments. For outdoor and extra-atmospheric environments, the traditional photovoltaic solar cell retains its place as the most durable long-term self replenishing power source with minimal environmental impact.
Although the hanging strips of PV material provided only a minimal amount of additional movement through wind interaction, they proved something of a hit with the local birds and squirrels as nest making materials. Fortunately, none of the materials presented a hazardous environment for the animals interacting with the experimental site.