Another company favoring the thermoelectric generator solution is Perpetua, which produces a flexible thermoelectric film. Jerry Wiant, Vice President of Marketing at Perpetua, believes that education is the company’s biggest short-term challenge, but feels energy harvesting is destined to be accepted on a wide scale: “The widely published reports of the pending explosive growth in wireless sensor network deployments is already intensifying the demand for energy harvesting solutions,” explained Wiant. “It is becoming clear that battery-changing labour costs and environmental concerns of disposing of batteries are going to be the primary drivers for widespread harvesting adoption.”
With technology already shipping in production quantities, Perpetuum, a spin-off from the UK’s University of Southampton but now also a VC-backed company, has developed its solution around a different principal; electromagnetic induction. Using the same basic techniques seen in countless electric motors - albeit in reverse - the company’s technology also targets wireless sensing in industrial automation. Predominantly the technology harnesses vibration created by the machines being monitored, making the wireless sensing node symbiotic with its power source. For this reason there is little need for storing excess power, but Perpetuum’s President, Roy Freeland, who is also the co-chair of the ISA100.18 Power Sources Working Group, does believe that better power management and its storage will be critical to the future success of energy harvesting.
One of the objectives of the Working Group is to address power management, which could include defining the average power output that any particular method of energy harvesting must produce.
This is perhaps more relevant for energy harvested using vibration because, as Freeland explained, the energy produced is dependent on the efficiency of the converter which is, in turn, dependent on the method used to harness the energy. This requires a ‘tuned’ solution which is optimal at the resonant frequency of the vibration source. For machinery running AC induction motors, for example, this may be 100Hz, but for an energy harvester attached to a locomotive, the frequency may be significantly different and prone to change. Perpetuum’s technology differentiator is the way it dynamical adjusts to these changes, to maximize the energy harvested.
Thinergy’s solid-state flexible and rechargeable thin-film cells are only 0.17mm thick.