Energy harvesting (EH) or converting renewable or existing sources of energy to electrical power can occur with several sources including light, heat, and motion providing the input. Photoelectric, thermoelectric, piezoelectric and electrodynamic techniques are well-known and often used to power sensing nodes that transmit data to a central controller.
Depending on how much light is available on a consistent basis and how much energy is needed, photoelectric power conversion provides a potential source of energy even in an indoor environment. Table 1 shows a snapshot of the capabilities of popular energy harvesting techniques. These capabilities are continuously improving.
More commonly in industrial situations, the machinery provides the inherent energy sources with heat and vibration and other motion for electromagnetic and electrodynamic energy conversion techniques. For example, a thermoelectric generator (TEG) can use the temperature difference between a motor and the ambient, in some cases as low as 10°C or even less,to provide the energy to power a wireless sensor node as shown in Figure 1. No matter what EH technique is used, the sensor(s) could provide the critical input for machine health monitoring system but could also be an easily installed (no wiring required) feedback element in the control system.
For those interested in more energy harvesting information including the newest techniques, Sensors Expo 2017, June 27-29 in San Jose, CA, provides EH presentations and a focused EH display area on the show floor. On Tuesday, June 27 the preconference symposium, “Energy Harvesting and Energy Efficient Power Solutions for Sensor Applications – Tutorials” provides a full-day focused on real-world applications of existing technologies. On Wednesday, June 2 8 the EH track in the sessions provides conference attendees five additional opportunities to learn more.
Table 1. Power generated by popular energy harvesting sources. Source: Understanding Smart Sensors, 3rd Edition, Artech House.
Figure 1. The elements of an energy harvesting powered wireless. sensor node.