The newscast below has been aired on many news stations nationwide. The kid in the video has an invention to charge a phone using some generator device in a shoe that generates power with footsteps as you run.

The kid seems confident and all, but I only trust inventors who have some more years under their belt, and maybe some gray hair. The kid is just too arrogant, which always raises questions for me. As a co-worker of mine would say, "he doesn't know how much he doesn't know."

My question: How much power will really be generated by some device in your shoe?

Those of us who have been to the gym know that sustaining significant "watts" on the display of the stationary bicycle is more difficult than we think it should be. Human power is not high, unless you are in really good shape.

But only a few watts are needed to charge a phone, --right?? Well, not so fast. Turns out "fast" charging on an iphone is 20 to 30 watts (from a google search). Slow charging which takes much of the night to charge your phone is like 5 watts, or maybe 2.5 watts depending.

I'm pretty convinced that a generator in your shoe will barely reach 5 watts, but my calculations may be wrong --- which is what I was hoping for a 2nd opinion on.

But if my calculations are correct, then is it really worth it to put a generator in your shoe? Or would it be better to just bring one of those USB batteries next time?

The cost of a generator in your shoe has to be the same or more than a USB battery, so I know what I'd choose.

But then again, maybe I'm too skeptical and this kid actually does have a marvelous idea.

It's just a proof of concept, it doesn't mean it would actually be financially viable. You can 100% collect energy from any movement of mass. There's nothing shocking here, at least hopefully not.

Scrolling through their page it definitely appears to be a real news company.

Creator of landfill. Buying shit and tinkering, winning plastic trophies and filling boxes with crap. He's invented nothing useful here.

Solar cell chargers are more practical. Hand cranks are also available and more effective at delivering charge from calories burned.

Using google or duck duck go and searching for “how much energy can be captured from walking” reveals dozens of articles about KEH, kinetic energy harvesting, going back 20 years. This 2016 article from UW-Madison claims up to 10 watts per shoe: Link.

Picture from UW-Madison article:


But hey, we’re making great strides towards a shoe phone.

Without looking at anything or really working through it in my mind, 10W (1A @ 5V)should be doable. That's about the minimum to charge most modern phones while the screen is active. You're only generating power on the strike & push motion, so you'll need some type of buffer to keep from cycling the charger - capacitor, battery or mechanical. Capacitor would be the cheapest & easiest, a battery is probably what would win out for cost/benefit, something like a flywheel would probably be the highest performance, but imagine a flywheel in your shoe.
The problem isn't if it can be done, it's if it can be done and still meet other criteria - such as comfort, longevity and how the fuck do you have a phone cabled to your foot while you run? wireless doesn't solve your problem because you need to have your phone strapped to your damn foot.

Now just looking at the intro-picture of the video & the picture posted after, the UW has a large outsole - not exactly a running shoe. the 'new' one looks to be in a much smaller, lighter shoe. If he has 10W+ in there & it doesn't compromise the feel/function/longevity of the shoe, he might be doing it right. It's still not that useful. Those look to be trail running shoes, so he might be considering the problem to be that he's far from home & needs to charge. One, he's making it harder to walk/run, which is the primary purpose. Two, a solar cell in a hat is probably just as effective, simpler and doesn't make it harder to move. So I don't think he has the best solution to that problem.

As a quality engineer, I spend a lot of time & frustration responding to "we spent a lot of money on this" with "it doesn't solve the problem".

Whether it would be useful, practical or interesting would depend on cost, efficiency, output and all sorts of other details, but theoretically valid.

There is no free lunch. TANSTAAFL. It would make walking a bit more effort, with that effort partly going into electricity output and partly into heat loss through inefficiency. Hopefully not too much heat for an athletic shoe (or put it into snow boots and lean into the heat loss?)

quote:

Originally posted by joel9507:
Whether it would be useful, practical or interesting would depend on cost, efficiency, output and all sorts of other details, but theoretically valid.

There is no free lunch. TANSTAAFL. It would make walking a bit more effort, with that effort partly going into electricity output and partly into heat loss through inefficiency. Hopefully not too much heat for an athletic shoe (or put it into snow boots and lean into the heat loss?)

No free lunch, but done right the energy would probably only come from the heel strike portion of the stride. If anything, this would provide a cushioning effect and could potentially make walking more comfortable.

quote:

But hey, we’re making great strides towards a shoe phone.

You can have the shoe phone, I'll take Agent 99!

The military had projects looking at this, years ago. Not sure what came of it.

Might not have been worth the weight.

quote:

Originally posted by trapper189:
Using google or duck duck go and searching for “how much energy can be captured from walking” reveals dozens of articles about KEH, kinetic energy harvesting, going back 20 years. This 2016 article from UW-Madison claims up to 10 watts per shoe: Link.

Picture from UW-Madison article:
{snip}

But hey, we’re making great strides towards a shoe phone.

Looking at that UW article, the so called genius inventor kid DIDN'T INVENT A DAMN THING.

It's customary to do a search for "prior art" which is normally the first step before claiming that you invented something. But no, the media just jumps on it and feeds this kid's ego.

Just another fraud.

quote:

Originally posted by snidera:
Without looking at anything or really working through it in my mind, 10W (1A @ 5V)should be doable. That's about the minimum to charge most modern phones while the screen is active. You're only generating power on the strike & push motion, so you'll need some type of buffer to keep from cycling the charger - capacitor, battery or mechanical. Capacitor would be the cheapest & easiest, a battery is probably what would win out for cost/benefit, something like a flywheel would probably be the highest performance, but imagine a flywheel in your shoe.
The problem isn't if it can be done, it's if it can be done and still meet other criteria - such as comfort, longevity and how the fuck do you have a phone cabled to your foot while you run? wireless doesn't solve your problem because you need to have your phone strapped to your damn foot.

that's the part they didn't really show --- a wire going from the phone to the shoe. Yup, not very practical.

And yeah, if you need a battery anyway for the between step energy storage, then why not just use a charged battery to begin with....

One small step for man, one giant charge for iPhone.

quote:

Originally posted by architect:

You can have the shoe phone, I'll take Agent 99!

I think thats Stefanie Powers from Girl From Uncle.
99 was Barbara Feldon. But I aint choosy!

A solution in search of a need/problem?

That’s how I see it anyways.