In the future: power your gadgets just by hiking!

There is a kinetic energy charger already in the marketplace http://www.npowerpeg.com/. It would be great to see something that is lighter and more effective.

The problem with these schemes is the energy isn't 'free'–even if the boots were somehow the same weight as conventional footwear, walking in them would require extra effort to generate electricity. Which means more fatigue at the end of the day, and prob. more calories needed, hence more food carried.

No free lunch.

David, I think you may want to reconsider your logic. While you are correct, the law of Conservation of energy cannot be broken, you can change in what state that energy exists. If a system was developed to absorb the vibrations / impacts that normally occur during walking and translate them into electrical current, they would thus reduce the overall impact transferred to the musculoskeletal system (if even by a small amount), thereby reducing fatigue and necessary energy expended (as a function of fatigue). The easiest way to think of this is in an inverse setup, in which some cities have installed sidewalks that generate electrical current from the impact of walking. These sidewalks are no easier or harder to walk on, and simply work by converting transferred energy into electrical current, rather than vibration (heat).

I'm glad Cameron went into it so I didn't have to.

Just capturing energy that would otherwise be wasted. Same concept as a turbocharger.

I don't know – maybe a different part of the anatomy. Feet and gait are very important for backpacking and I'm not sure I would want to mess with the physics of that, as it would of necessity do.

"Same concept as a turbocharger."

Not quite. A turbo injects more oxygen into the system, which leads to more energy production.

With kinetic boots, formerly "wasted" energy is captured.

A better automotive analogy would be a thermocouple generating electricity by scavenging exhaust heat.

regenerative brakes on a Prius

From Wikipedia:

"…a turbocharger does not place a direct mechanical load on the engine… This is more efficient, because it uses the otherwise wasted energy of the exhaust gas to drive the compressor."

ahhh….

Now that's informative…

You guys seem to love to argue about irrelevant stuff.

The day physics becomes irrelevant is the day I am out of a job… oh and the day the universe collapses on itself.

Oh, you mean irreverent in terms of backpacking… hmmm… I haven't noticed that on this forum before…

Please pardon my liberal use of ellipses.

in terms of which analogy is the best… …. ………

Oh, we get a new one of these hyped up in the press about every 12 months or so. Boots, packs, whatever. They never work, but hope springs eternal.

The amount of 'free' energy available from your body is microscopic. Beyond that, you have to put real work into the device, and the devices are always heavy and expensive. A couple of spare Lithium AA batteries are much lighter, or sometimes a very light solar cell for very long trips.

Cheers

Roger, keep in mind that until not all that long ago, people were saying the same thing about solar panels, lithium batteries, and the like. I'd be extremely surprised if within the next few years we didn't see something related to energy storage that right now is nothing more than a dream.

Interesting how everyone consistantly focuses on power production in these types of discussions, when the biggest breakthroughs have really come from power consumption and conservation. The common flashlight is a prime example. Powering a standard bulb with a lithium battery is good, but powering an LED with a standard battery is much better. Obviously working both sides of the equation produces phenomenal results, but the bigger gains come from the consumption side.

Hi Cameron

> until not all that long ago, people were saying the same thing about solar panels,
> lithium batteries, and the like. I'd be extremely surprised if within the next few
> years we didn't see something related to energy storage that right now is nothing
> more than a dream.

Energy STORAGE has nothing to do with how much energy you can tap out of someone's boots or pack while walking. The two are almost entirely unrelated. And how much energy you can extract from motion is really limited by fundamental physics, not by current technology. One gets used to the dreamers after a few years.

Cheers

"Just capturing energy that would otherwise be wasted. Same concept as a turbocharger."

*pedant alert

Bit of a car nut so thought i'd jump in here.
Turbo's do have a parasitic effect on the car, the impeller does a pretty good job of blocking the exhaust gases.
Modern turbo's are a lot better but they still rob the engine of a certain amount of power.

Obviously once they've "spun up" they put in they help force in more energy than they use, but stil there is a parasitic loss.

One really significant amount of energy that is wasted for a hiker like me, as opposed to military, is the potential energy that I create when I do work hiking up to 5000 feet of positive vertical in a day (not net, just adding up all the uphills). Not only is that work/energy wasted in negative work on the way down, but it results in a force being applied to my joints, and my legs have to exert a force a equivalent to the force of gravity (or more specifically the component of gravity parallel to the slope of the hill) in order to prevent my acceleration down the hill. If there were a way to harness that force to do a small amount of work in the shoe (compressing a piston or better yet a liquid to create an electrical potential) that might be interesting. As an alternative but less effective method, maybe integrate something into your trekking pole shocks, although I dislike shocks on trekking poles. Shoes would be better as they take most of the pressure. You would need to be able to turn it off on the uphills (or it would make you do more work). The amount of potential energy that I create in those vertical ascents is around 1.2 million joules, or about half the energy in a fully charged car battery. How much of that you might recover I don't know, and of course the entire system needs to weigh less than 1.4 ounces, i.e. the weight of one spare cell phone battery that I carry :)

There, is that enough useless physics for everyone?

"There, is that enough useless physics for everyone?"

Definitely enough sketchy physics for one thread.

Expecting the usual design for a perpetual motion machine any post now.

A chemical engineer getting lectured on pump losses?

This thread is getting interesting.

Yes they have a small negative effect caused by the backpressure in the exhaust flow. It is still achieving the same goal (recapturing wasted energy).

In fact it is similar to how carrying an extra few ounces for the power generation unit would cause a small loss in hiking efficiency. However the ounces of extra batteries they would (in theory) replace would decrease efficiency more (similar to adding cylinders to match a twin turbo's added increase).

My roommate doesn't believe in turbos though, evidenced by his LS7 corvette.

I can't believe people are nagging on a one word example I put 3 seconds of thought into lol. Oh well, time to get out of the house.

"Modern turbo's are a lot better but they still rob the engine of a certain amount of power."

True. Which is why we should use Nitrous. Vroom Vroom :)

Ryan