Energy Harvesting and Current State of the Technology with Application to Traffic Monitoring

Autonomous systems present the future of wireless networks and applications. Systems that are able to go anywhere and be truly "autonomous" have a huge advantage over those dependent on finite power sources. They do not require regular maintenance of a battery; therefore they can be put into places where it might be difficult to replace components. The question is "How to power an autonomous system?" Energy harvesting has been proposed as a means to harness energy from a system's operating environment and convert it to electricity. Research was undertaken in order to thoroughly investigate the current state of harvesting technologies and the results are presented in a comprehensive literature review. The review focuses on the underlying theory and the operating principles used by electromagnetic, piezoelectric, and electrostatic harvesters. We have also investigated and discussed the research and methodology used by previous researchers in developing their own systems. From preliminary analysis, it is evident that harvesters alone are incapable of powering large loads directly; therefore harvester circuits have also been investigated. Consequently the literature review presents a detailed overview of harvesting circuits and describes the work done in the development of circuits that manage harvested power and storage devices. This article also discusses a number of harvested energy powered traffic monitoring system and introduces our own novel proposed system.