I’ve been wondering recently about the power of human movement to generate, well, power. We do so many movements, from turning around or shaking hands to walking to standing up or sitting down, etc. – not to mention aerobic exercise. Has anyone ever tried to tap that movement as an energy source?
I would imagine that it would be possible to do it in a way that doesn’t involve massive amounts of wires and electrodes that would be annoying and inconvenient. Does anyone have any insight or info on this?
The problem is if you want to harvest the energy, you have to apply force to something. Just as an example, if you shake hands with someone, both hands would have to be attached to a rope/strap/whatever that turns a generator in order to use that energy.
A treadmill, stationary bike or stairclimber could similarly be used to generate electricity.
Of course people have been tapping into it. Automatic watches are/were probably the most common example. Not yet (AFAIK) enough power for a smartphone, if that’s what you need, at least not without special accessories.
It seems most interest in this sort of gear is for making one able to power one’s own electronic devices. And my cursory reading of the paper makes me think the tech isn’t quite there yet, but isn’t that far away.
The tech has gotten more sophisticated than I recall, in the days of my first self-winding watch, back in the 1960’s.
I suppose we can assume the wristwatch or telephone or whatever it is is attached to you or in a pocket so that it is subjected to acceleration and vibration as you walk around. The trick is to make such a thing so you would not even notice it; something that required, for instance, vigorous hand cranking would not qualify, unless I misunderstood the OP.
If the device is getting useful work out, then you must be doing that much more work. That is to say, it’ll be harder to walk, and you’ll get tired more quickly, and so on. So it’s only viable in one of two cases: If the amount of energy needed is so small that you wouldn’t even notice (like with self-winding watches), or if the user doesn’t mind doing extra work. And if it’s the latter, then you don’t need to restrict yourself to incidental motion; you can have the person making extra movements they wouldn’t otherwise.
The simplest way to implement this is to power your transportation with your own muscles, by walking or riding a bike in situations where you currently drive.
There’s a brief discussion of a movement powered system during this episode of “Wait Wait Don’t Tell Me” Clippy And Paula : NPR - scroll down to the mention of “Twinkle, Twinkle”
Or if it is work that would be done in any case. Clothing bends, shoes absorb the force of impact, in any case, with the work otherwise being lost as heat. The idea can be similar to regen braking.
I have always felt that small storage batteries charged by skateboards, bikes would be handy for small electronic devices. A device kind of like those tops we used to push on to make spin could be built into shoes. a once inch power stroke would take some getting used to.
In at least one science fiction novel, Portal to E’ewere by Irma Walker, people create energy by pedaling stationary bicycles for hours at a time in a dystopian future.
No, even if a movement would be done anyway, harvesting energy means it will take more effort to make that same movement. A piece of clothing that generates electricity from movement would be stiffer than conventional clothing, requiring more effort to bend your arms or legs. Walking with energy-absorbing shoes will take more effort.
If no changes are made to the clothes or shoes, then the harvesting system’s energy take-off will be in addition to the energy converted to heat in the clothes or shoes. Then scr4’s answer will apply perfectly. IOW, he’s got the underlying principles right, but maybe not the real-world details.
Part of the design of current shoes is to provide X amount of cushioning and impact absorbance. Right now the only way to dissipate that energy absorption is as heat. *If *we can convert some of that energy to electricity directly, we can scrimp on the remaining part that wastes the rest as heat. Resulting in the same mechanical outcome and no extra human effort needed to walk.
Plus, as Chronos almost said, if the incremental effort is small enough it practically speaking won’t matter. Yes, there is no free lunch or perpetual motion machine here.
But if we’re only trying to harvest a few milliwatts of power with a pair of shoes, and we unsmartly do that in addition the ordinary friction of ordinary shoes, then a healthy adult still will never notice the difference. Walking into a 1/4mph breeze or up a 1" per mile slope will be larger energy draws than that.
This is also where a hand-cranked LED flashlight works a lot better than a hand-cranked incandescent one. The progress in the rest of our electronics towards low power consumption certainly helps reduce the demand for power down to the level that it might be lost in the sauce. You could never operate a WWII walkie talkie off impreceptable amounts of human effort. You might be able to operate a modern GPS navigator off imperceptible amounts.
This isn’t quite true. An elastic material (metal springs, elastic rubber soles, etc) can absorb impact by deforming, and the energy is stored mechanically, not dissipated. The energy is then used to propel the wearer forward in the next step. If that energy is instead converted into electricity, that would slow down the wearer.