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Batteries not included: How small-scale energy harvesting will power the future

Good vibrations: Piezoelectric energy harvesting

Meanwhile at dance clubs all over the globe, patrons gleefully bop the night away. Apparently there’ll always be a place in this world for those who have a fixation for the gyration. But we digress. The point here is that some of these clubs are different than others. Seems there’s a movement afoot to “green up” our dance halls. And from re-used water to rooftop turbines, that movement grows stronger by the day.

Indeed, it extends all the way down to the floor. The dance floor, that is.

You see, there’s a tremendous amount of energy generated when dozens or hundreds of people repeatedly bounce to the beat. Until now, that energy dissipated into the floor and whatever lay beneath it. But what if you could somehow harness it?

With “piezoelectricity,” you can. Seems there are certain materials in this world, crystal- and ceramic-based, that generate wattage when put under pressure. If you place those materials in a spot where they’ll receive a constant pounding – say, in the floor of a dance club – you have a way of tapping into that pounding and producing useable electricity. In fact, companies such as Rotterdam’s Sustainable Dance Club are already doing just that, installing illuminated dance floors that are, in effect, self-powering.

The piezoelectric push is not confined to dance clubs. There’s a railway station in Tokyo that uses the effect to power display boards and ticket gates, and a sidewalk in Paris that juices the streetlights.

At the Cornell Nanoscale Science and Technology in Ithaca, New York, plans are underway to bring all this groovy piezoelectric stuff into the consumer world, albeit with a somewhat different approach. The name of the outfit is MicroGen Systems, Inc, and the people involved are seemingly in it for the long haul. CEO Mike Perrotta tells us the company was founded in 2007 and incorporated in 2010 after a “major investment contract was signed.” Perrotta estimates man hours thus far to be in the 20,000 range.microgen's first generation device battery power energy piezoelectric generationAt the heart of the push is MicroGen’s proprietary Piezoelectric Vibrational Energy Harvester (PZEH) technology. According to MicroGen, the concept will extend rechargeable battery lifetimes or eliminate the need for batteries altogether. An early permutation is the “BOLT060 MicroPower Generator,” a teeny-tiny gizmo that looks like a computer CPU. It operates purely by applied vibration, and should theoretically function for 20 years or more.

Why a miniature harvesting technology based on vibrations?

“Vibrations are everywhere, and do not depend on temperature differential, light, radio frequency, or other types of sources,” says Perrotta. “Everything that is plugged in vibrates, and many things have a natural harmonic even if they are not plugged into electric. We have even had conversations about placing these devices in a cow’s stomach, with a temperature sensor and wireless radio, to monitor livestock health and conditions. I haven’t seen anything plugged into livestock yet.”

Bovines aside, Perrotta envisions MicroGen piezoelectric technology in a wide variety of low-draw applications. “Think of us as a micro power plant, thus the name MicroGen. Flashlights and the like will require too much power (for our technology) to recharge. However, you can have a flashlight app on your mobile and that works pretty good.”

“Our target in the consumer space is ‘trickle charging’ a mobile device, so that the batteries do not wind down as quickly after the last plug-in charge.”

“Clothes dryers are another example, where current sensor technology only measures the average humidity of the entire load, thus requiring more energy. The sensor can now be relocated with our device powering it, and therefore more accurately indicate the humidity of the clothing, and stop the dryer more accurately. This will save significant energy consumption. Tire-pressure monitoring systems, now in every vehicle in the US, Canada and European markets, may be able to go battery-less. If not, our systems will last the life of the car, thus reducing the number of batteries in a landfill. Many more examples, especially in the industrial and commercial arenas, are targeted to reduce energy consumption, improve safety, and security as well.”

Perrotta claims the technology is currently capable of delivering a rather mild 200 microwatts, though he expects that figure to double and perhaps triple in the short term. The increasing efficiency of mobile devices could also help. “We’ve certainly seen a great degree of reduction, in the order of 50 to 80 percent, on the power needs of these devices, even over the last couple of years,” Perotta says. “We expect that will continue, and our power output per square millimeter to increase. Our target in the consumer space is ‘trickle charging’ a mobile device, so that the batteries do not wind down as quickly after the last plug-in charge.”

In the near term MicroGen devices will be coupled with either a solid-state battery or a super capacitor. But the eventual goal, he says, “is to be battery-less. However, most of that will depend upon the trends around sensors and wireless radio power needs.”

Whether MicroGen’s solution achieves those goals remains to be seen, though the mere potential was enough to compel the New York State Energy Research and Development Authority to award the company a $1.2 million grant just a month ago.  

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