By Jeff Andle
From the June 2023 Issue
According to research from Statista, the number of IoT devices is expected to reach nearly 30 billion before the end of this decade. Many of these devices will be deployed into commercial or industrial spaces, especially smaller-scale wireless products like sensors, transmitters, and switches. These devices are remarkably useful when it comes to keeping a facility running smoothly, but as millions more roll out each year, the challenge of how to power them looms larger and larger for facility managers. Coin cell batteries have long been the default power option, but they bring with them costly downsides at scale. They are not optimized for small-scale “pulse-power applications,” they are a time-consuming nuisance to regularly replace, and they generate a substantial amount of waste. This article will explain why each of those issues should matter to facilities managers and will introduce an alternative style of IoT device power generation that could significantly ease their energy management burden.
Power Supply & Draw Clash
While wireless electronic devices like sensors, transmitters, and switches operate at low average currents, they don’t necessarily draw power from coin-cell batteries at low currents during peak operation. They experience short spikes of immediate activity followed by long periods of complete inactivity. During the current spikes, batteries operate well above the average currents that were used to benchmark these devices. During periods of inactivity, some of the power stored in batteries is just wasted away because of small leakage currents. Both extremes are less efficient than if the battery could operate at its average current. This mismatch between the power draws of these types of devices and the optimally efficient power delivery style of batteries results in hindered device performance and faster battery depletion than anticipated (and advertised). That means facility managers have to replace batteries more often than they bargained for without even getting peak performance from the devices.
What Happens When Batteries Run Out
A battery dying presents a number of complications, starting most obviously with the fact that the device it is powering will stop working. That can have dire consequences. Some environments like industrial settings avoid these issues with proactive maintenance by requiring regular battery inspection and/or replacement, but this constant need is remarkably costly, time-consuming, and tedious for everyone involved. If you have 10 of these small-scale wireless devices across your facility, that means every two years or so you’ll need to buy 10 new batteries and then dedicate the man-hours to replacing all of them. That doesn’t seem so bad, but what if you have 100 devices? Or 100,000? As our spaces grow more and more connected, the prospect of a facilities team simply replacing all these batteries by hand starts to sound increasingly unrealistic and uneconomical.
At 30 billion deployed devices, even a 10-year battery lifetime means that three billion battery changes would be required annually, interspersed among 30 billion inspections. At a rate of three per hour, including travel between locations, 10 billion man-hours—that is five million full-time workers—are needed to support the batteries for the supposedly automated and autonomous IIOT.
Beyond the device performance concerns and battery replacement costs, they are also incredibly wasteful. Environmental groups have reported that Americans dispose of more than three billion batteries annually, causing 180,000 tons of hazardous waste. EnABLES, an EU-funded energy research project, claims that nearly 80 million batteries powering IoT devices will be discarded every day by 2025, if no alternatives arise. For facility managers looking to maintain greener buildings, this is obviously problematic.
A Sustainable, Scalable Alternative
Advancements in electromagnetism, microelectronics, power conversion circuitry, and nano- and pico-power technology have unlocked the potential for many small-scale devices to be powered by their very triggering condition–consider a fire door sensor whose alert is triggered when doors are open and closed or an industrial switch whose action is powered by the switch being flipped.
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Technology Is The Backbone Of A Successful Hybrid WorkforceThis kinetic energy harvesting process involves electromagnetic induction, where a kinetic force such as pressing a button moves a small magnet through a metal coil, thereby creating an electromagnetic charge in accordance with Faraday’s Law. This charge can power various actions such as transmitting data. The quality, reliability, and functionality of the data transmission depends on the magnitude of the electromagnetic charge, but until recently, kinetic energy harvesting technology could not capture the charge efficiently enough to power these devices, nor were devices able to start up on such low voltage. Things have changed and kinetic energy harvesting is now a viable alternative to batteries for many applications.
We have a long way to go before batteries are phased out from our IoT devices, but if facility managers want to speed up deployment, we need to take steps to strip out the things holding back device performance, design, and sustainability. That means saying goodbye to energy from batteries wherever possible and instead sourcing it from motion from the devices’ own surroundings.
Dr. Andle, Chief RF Consultant for WePower Technologies, has been active in the area of piezoelectric materials, device modeling and design, sub-systems, and systems since 1980. This includes resonator and filter design at RF Monolithics, fluid sensor design at BiODE and Vectron, and SAW wireless sensor systems at Vectron, IntelliSAW, Mnemonics, and Cardian. Dr. Andle retired in December 2021 and has since been consulting in RF, IIoT, power, and PCB layout.
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