Perpetual Power?
February / March 2010
Volume 8 Number 1
With today's ever-advancing technology, we increasingly rely on sensors to keep tabs on all kinds of industrial operating conditions. But what good is a wireless sensor without a long term, cost-effective power source? At the forefront of our shared national and international priorities, the ability to deliver power to such mechanisms in a sustainable way represents a major global need.
Now imagine a technology that can power wireless sensors indefinitely by harvesting energy naturally from temperature differences in the environment—€”a technology that allows managers and operators in a variety of fields to focus their time, attention and valuable resources on operations and conditions, rather than on manually checking equipment and systematically replacing wireless sensor batteries. Jon Hofmeister recognized the magnitude of the opportunity when he founded Perpetua Power Source Technologies Inc. and licensed technology developed at Pacific Northwest National Laboratory that was capable of doing just that.
Based on a disruptive PNNL technology called the Thermoelectric Ambient Energy Harvester, Perpetua's award-winning Perpetua Power Puck—„ answers the call for a renewable source of energy running compact, low-power devices such as wireless sensors by pulling energy directly from its surrounding environment.
Electricity is in fact produced whenever the Power Puck is exposed to temperature differences, but is also stored, regulated and delivered with steady voltage just like a battery, so no design changes are required by users of the long-life, renewable power sources.
The Power Puck's operating technology is based on a novel implementation of a proven technology called thermoelectrics—€”employed in continuous use by NASA for over 45 years without a single failure. Thermoelectric generators convert temperature differences across dissimilar materials into useful electricity.
The unique core technology used here includes an assembly of ultra-thin thermocouples in a flexible configuration that exploits small temperature differences occurring naturally in the environment of the application—€”e.g., ground-to-air, water-to-air, or skin-to-air interfaces. Depending on the magnitude of the temperature range the device's thermocouples are exposed to, electrical outputs range from the hundreds of microwatts to hundreds of milliwatts. The thermocouples are packaged along with power management electronics into robust products that provide maintenance-free, continuous power for the lifetime of the application.
The self-sustaining nature of this technology makes it especially valuable for monitoring the integrity of critical structures including pipelines, dams, buildings and bridges—€”applications where sensors communicate with remote facilities, and maintenance or repair is costly and logistically difficult. The Power Puck can replace or extend the life of traditional batteries used for these applications, and last as long as the sensors and transmitters they power. Thus, the operating life and lifecycle costs of remote monitoring systems are no longer directly or indirectly dictated by the shorter—€”months to several-year—€”lifespan of traditional power sources, allowing for much more efficient use of operational resources.
The environment also benefits from the use of this renewable power source. With no moving parts, the Power Puck provides a more efficient and cost-effective power source for a number of applications. And its long lifespan virtually eliminates the need for disposal of batteries and other short-lived power sources. "Most customers look first to the economic savings the Power Puck can provide, but there is a growing number that come to us because they are concerned about the negative environmental impact of disposing of more and more batteries into landfills," says Jon Hofmeister. "Particularly in the wireless sensor industry, where volumes this decade will top a billion units, the impacts of battery disposal are significant. Fortune 100 companies down to small and scrappy startups fortunately now have a viable options for long-life, self-replenishing, easy-to-install and cost effective power solutions for their wireless sensor systems."
The Perpetua Power Puck recently received the R&D 100 Award from R&D Magazine as well as a 2009 National Federal Laboratory Consortium Award for Excellence in Technology Transfer. Perpetua has expanded its market for the Power Puck to include industrial monitoring applications including pumps and motors, critical semiconductor equipment, and building energy efficiency. Working with partners in each area, Perpetua has recently demonstrated the Power Puck's versatility and value as a renewable power source in such applications.
One of Perpetua's partners, Evanite Fiber Corp., is a leading manufacturer of specialty glass fiber for filtration media, battery separators and insulation. The health of its vast network of industrial motors and blowers is critical to the success of its 24/7 manufacturing operations. Until now, it had relied on sending out a technician monthly to take handheld vibration readings and manually comparing month-to-month data to identify potential signs of maintenance need or failure.
Evanite's search for a more efficient and robust solution led it to consider a wireless sensor network—€”easy to deploy, scalable, and enabling them to view daily information right on their laptop or smart phone. Having to change batteries every three months or so for each of the wireless sensors they wish to deploy, however, was a significant concern. Perpetua collaborated with Evanite in developing and testing a vibration monitoring solution that incorporated the Perpetua Power Puck—€”changing the need for battery replacements from a matter of months to more than ten years.
Another Perpetua partnership focused on building energy efficiency began with a study for Oregon State University's Sustainability Office. The office had for some time wanted to gather heat loss data from their extensive steam pipe heating network to better understand how they may be able to improve its energy efficiency program.
Recognizing that even little improvements can add up quickly, the key is to establish a quantitative baseline for evaluating modifications to the system through upgrades such as adding insulation to the miles of warm pipes at the university. Tapping waste heat directly from the pipes being monitored, the office was able to gather the desired baseline data using Perpetua's remote heat flux sensors and allow the university to make informed decisions about where and when to make system-wide improvements.
Ali Madison is a PNNL communications specialist.
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