Energy harvesting is rapidly maturing to become an important sector in the electronics industry, having risen over the past five years to take its place as a competent technology enabling an expanding market. While the pioneering companies behind the technology have faced many challenges in that time, the market now faces one of its biggest obstacles; convincing system integrators that it is a viable alternative to battery packs.
According to some leading companies in the field, the technology has proved it delivers the levels of energy needed for its target applications, in a reliable, sustainable way. The number of installations using harvested energy grows daily, and many forms of energy harvesting now exist; from thermopiles to vibration, solar to RF. As they all deliver relatively modest amounts of energy, they also share a common application area, which today is predominantly providing power for wireless sensor nodes, used for monitoring industrial/automation equipment and machinery.
Micropelt’s Thermoelectric Generator (TEG) uses MEMS technology to sandwich n-type and p-type substrates to harness Seebeck’s Law.
But even with significant demand now coming from end-users in this field, it seems system integrators are yet to be fully convinced of harvested energy’s credentials. This is due in part to the fragmentation that currently exists amongst competing suppliers as, while standards exist for batteries, the same isn’t yet true for harvested energy. This places another hurdle in the way of their being specified, but one that is comparatively easier to overcome than the laws of physics.
Micropelt’s TEG device shown on a pen, can be directly mounted on a heatsink to maximize the temperature gradient across its faces.
Because they increasingly target the same class of applications as batteries; typically those that need limited power often sourced from replaceable, removable, rechargeable or renewable cells, this breakdown in the supply chain threatens to impede the future progress of energy harvesting.
However, recent efforts backed by the ISA (Instrumentation, Systems and Automation Society) have created a working group that intends to develop standards for the interchangeability of power modules for wireless sensor nodes (WSNs), which will cover the electrical and mechanical characteristics of power modules whether they be batteries, fuel cells or energy harvesters.