Energy harvesting—drawing and then using small amounts of "free" power from various physical phenomena—seems like a great idea that is always "just around the corner." But we may have turned that corner, judging from the activity at the Energy Harvesting & Storage Conference (Cambridge, MA).
I'm just back from the event and saw about 30 modest but vibrant vendor exhibits/booths (by my count)--spanning companies you may not have heard of, to much-larger IC and system vendors--and 400 attendees (that's the organizer's head count). [See the show-floor photos at the bottom of this report.] There were also in-depth tutorial tracks and keynote addresses on technical issues, installed applications, and down-and-dirty engineering details.
Why harvesting, and why now? As to "why?", harvesting is a great fit for applications where conventional power (usually a battery which has to be changed) is detrimental or impractical; there is no need to explain this advantage for the EE Times readership. As to "why now?": it is a coming together of the necessary elements towards that critical mass needed for a successful system designs and installations.
Certainly, the basic transducers have improved somewhat but haven't changed much, since they are constrained by the laws of physics; they transform light, vibration, thermal differentials, ambient RF, and fluid flow into electrical energy. But now, you also have the other critical elements needed for a viable system, and at competitive prices: 1) efficient components to capture the minuscule available energy; 2) ICs which can manage the storage and use of the energy; 3) storage using supercapacitors, low-leakage conventional capacitors, and rechargeable batteries; and 4) application ICs and designs which can actually implement fairly impressive and meaningful tasks using just a trickle of current, on the order of 10 to 100 microamps.
For example, I saw wireless building-energy-management data logging links, operating from extracted RF, as well as a piezoelectric-powered machine-monitoring unit which included a multiline LCD display and serial link. There were also vendors of essential building blocks, such as energy-storage components with the packaging, form factors, and electrical specifications tailored to the specific needs (capacity, charge/discharge rate, duty cycle).
No question, lots is happening at all levels in energy harvesting. So, has it hit the take-off inflection point? I don't like to make long-range "crystal ball" forecasts in this age of excessive hype and hope, but check back in a few years, and we'll all know the outcome with much greater certainty. ?