Wireless Technology

Call It Assault On Batteries

Energy harvesting promises to address their limitations for wireless devices

By Mark Rosenzweig, Editor in Chief

Battery-powered devices have altered our lives and workplaces in myriad ways. Of course, smartphones and laptop computers rank high on the list of key transformational developments. Meanwhile, wireless sensors and transmitters are assuming a bigger role in plant operations.

The roster of battery-powered equipment that we now rely upon seems almost endless, ranging from prosaic items like the key fobs that arm/disarm the locks and alarms on our cars to life-saving medical implants.

I keep on hand a “crank up” radio for emergencies.

Going way back, I recall marveling over the first small transistor radios. The attraction of carrying a radio in your shirt pocket and then listening to AM stations whenever you wanted was stupendous. I still remember tuning into the “Good Guys” on WMCA – 570 kHz in New York City on my petite made-in-Indianapolis “Regency TR-4” radio!

Then being a teenager with a small allowance, that radio sensitized me to the finite life and fiscal impact of batteries.

Fortunately, battery technology has progressed dramatically since those days. Today, lithium ion batteries provide high power in a compact form factor undreamt of not that long ago — although with the risk of fire from overheating in some circumstances. Meanwhile, common inexpensive alkaline batteries now boast shelf lives of up to 10 years.

Nevertheless, despite these advances, concerns over batteries persist.

On a personal level, I still worry a bit about a battery’s state of fitness when left for a long time in a device. That’s why I keep on hand a small emergency radio (for listening to weather information as well as regular broadcasts) that gets power from turning a crank a number of times.

Battery life also remains a sticking point for some industrial applications of wireless technology. Sure, a wireless sensor/transmitter can make getting data from a remote or inaccessible location feasible when it otherwise wouldn’t be. However, the need to limit the frequency of readings to ensure adequate battery life as well as the overall cost of battery replacement thwart use of wireless in some services.

Fortunately, developments in energy harvesting may alleviate these concerns by augmenting or even replacing batteries. We’ve long covered the idea of scavenging power by taking advantage of machinery vibrations or the temperature gradient between equipment and ambient conditions (see, e.g., “Energy Harvesting Widens Wireless’ Appeal”). Progress continues to occur. For instance, last month, we reported that researchers at MIT have developed a harvester that doesn’t require two different temperatures at a given time. Instead, the device works off the natural swings in ambient temperature that occur between day and night (“Temperature Swings Power Sensor”).

Meanwhile, commercially available harvesters continue to win over users. For example, this issue’s article “Energy Harvester Stars for Steam Monitoring,” highlights how a thermoelectric device with protruding heat-sink bristles now is teamed with a wireless transmitter in an inhospitable location at a process plant. It powers the transmitter during routine operations— significantly extending the life of the battery, which only gets called upon during turndowns and other situations involving loss of process heat.

While advances in batteries have ushered in the wireless era at plants, energy harvesters may significantly enhance the feasibility of more widespread adoption.

rosenzweigweb.jpgMARK ROSENZWEIG is Chemical Processing's Editor in Chief. Along with his emergency radio, he keeps around dozens of vintage typewriters and a Studebaker or two. You can email him at mrosenzweig@putman.net.