On-Demand Energy Harvesting Techniques - A System Level Perspective

Abstract

In recent years, energy harvesting has been generating great interests among researchers, scientists and engineers alike. One of the major reasons for this increased interest sterns from the desire to have autonomous perpetual power supplies for remote monitoring sensor nodes utilizing some of the already available and otherwise wasted energy in the environment in a very innovative and useful way (and at the same time, maintaining a green environment).

Scientists and engineers are constantly looking for ways of obtaining continuous and uninterrupted data from several points of interests especially remote or dangerous locations, using sensors coupled with RF transceivers, without the need of ever replacing or recharging the batteries that power these devices.

This is now made possible through energy harvesting technologies which serve as suitable power supply substitutes, in many cases, for low power devices. With the proliferation of wireless energy in the environment through different radio frequency bands as well as natural sources like solar, wind and heat energy, it has become a desirable thing to take advantage of their availability by harvesting and converting them to useful electrical energy forms.

The energy so harnessed or harvested could then be utilized in sensor nodes. Now, since these energy sources fluctuate from time to time, and from place to place, there is the need to have a form of energy accumulation, conversion, conditioning and storage. The stored energy would then be reconverted and used by the sensors nodes and/or RF transceivers when needed. The process through which this is done is referred to as energy management.

In this research work, many types of energy harvesting transducers were explored including – solar, thermal, electromagnetic and piezo/vibration. A proof of concept approach for an on-demand electromagnetic power generator is then presented towards the end. While most, if not all, of the energy harvesting techniques discussed needed some time to accumulate enough charge to operate their respective systems, the on-demand energy harvester makes energy available as at and when needed. In summary, a system level design is presented with suggested future research works.