Energy Harvesting & Storage Technology

Energy in the form of light, thermal, mechanical and electromagnetic radiation is present in virtually every environment. The harnessing and collection of this ambient energy into a useful form is called Energy Harvesting or Energy Scavenging. In the past, the methods of harvesting energy were not efficient enough to convert the relatively low levels of energy into an amount that can provide the power for an electronic system. Additionally, there has not been an adequate method of storing the energy gained from the transducers that was both permanent and efficient. Advances in both transducer technology and thin film batteries have made ambient energy harvesting a practical reality.


An Energy Harvesting power management system must be capable of capturing, converting, storing and delivering energy in a form that can be used to provide the power needed by the system it serves. A typical Energy Harvesting system starts with an energy collector or transducer device and depends on the type of energy one is trying to convert. These are typically solar or photovoltaic cells for light energy, piezoelectric for pressure, kinetic for movement, inductive for rotational or motion, thermoelectric for heat or temperature differential, and electromagnetic. The energy collected from these transducers must be converted to a form that can be stored for later use. In remote sensor systems or portable device applications that use Energy Harvesting a small rechargeable battery or storage capacitor is often employed to store the collected energy the system needs for operation. The drawbacks to each of these storage methods are numerous in that even rechargeable batteries wear out after a few hundred charge/discharge cycles and need to be replaced and super caps while they eventually change their characteristics, will self discharge rapidly, as much as 20% per day, causing much of the converted energy to be wasted. A more robust and permanent solution is to use an EnerChip thin-film battery as the energy storage element in the system to eliminate the need for replacement since it can support in excess of 5000 cycles and has a minimal self-discharge of less than 3% per month.

The final stage of the system conditions to stored energy to suit the requirements of the system. This could be as simple as a regulator and level shifter to a complex power control circuit that intelligently manages the power distribution to the system based on power needs and system operation.