Interest in energy harvesting, the process associated with the collection of low-grade energy from sources such as ambient or waste heat, human power, solar, thermal and kinetic energy, and their conversion into electrical energy, is gaining momentum. Viewed initially mainly as a convenient way of powering sensors, small wireless electronic devices and low-power systems, it is also opening up for opportunities use in larger applications. The more so when it is used in connection with certain types of energy storage systems.
Cutting the cord – less batteries please!
Tapping energy from low-grade sources is seen as an attractive solution for powering the growing number of electronic products and devices that operate independently from power networks or without batteries.
Energy harvesting, also known as energy scavenging, is already widely used for powering sensors and actuators, such as those found in certain types of MEMS (Micro-Electro-Mechanical Systems), which are increasingly deployed in sectors such as automotive and medical. International Standards for MEMS are prepared by IEC TC 47: Semiconductor devices, and they are tested by IECQ (IEC Quality Assessment System for Electronic Components) testing and certification.
Energy harvesting is useful for devices that do not require a lot of power and when changing batteries may present challenges, such as when they are installed in remote locations, or risks. This is the case in the medical field where energy-harvesting devices that can convert the movement of body parts such as the heart, lungs and diaphragm into energy could be used to power implantable devices – for instance, pacemakers. Research has been ongoing into these devices as well as into the piezoelectric materials that could be used in them. A self-powered cardiac pacemaker using a piezoelectric nanogenerator was demonstrated on a rat in June 2014.
Techniques to harvest energy for other medical devices are also being developed. One example is using jaw movements to power hearing aids, which avoids having to replace internal batteries. New energy harvesting processes, many of them highly ingenious, are being introduced all the time. Some have an entertainment value but may still lead to the development of useful applications. Many others pave the way for the development of more energy-efficient systems. Many IEC TCs (Technical Committees) deveop standards applicable to energy harvesting applications.
Written by Morand Fachot for our e-tech Magazine. To continue reading check out our e-tech article.