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Knee Brace Generates Electricity From Walking

Soulskill posted more than 6 years ago | from the runs-on-walks dept.

Power 128

ktulus cry brings news of a device that can power portable gadgets, prosthetic joints, and other mobile appliances by harvesting energy generated by walking. Researchers are working on making the device — still a moderately cumbersome 3.5 pounds — smaller while maintaining its energy harvesting capacity. CNet has a write-up with more pictures and a diagram of the device. "In the mode in which the brace is only activated while the knee is braking, the subjects required less than one watt of extra metabolic power for each watt of electricity they generated. A typical hand-crank generator, for comparison, takes an average of 6.4 watts of metabolic power to generate one watt of electricity because of inefficiencies of muscles and generators. A lighter version would be helpful to hikers or soldiers who don't have easy access to electricity. And the scientists say similar mechanisms could be built into prosthetic knees other implantable devices such as pacemakers or neurotransmitters that today require a battery, and periodic surgery to replace that battery."

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128 comments

Does it double its output ... (3, Funny)

MPAB (1074440) | more than 6 years ago | (#22370154)

by walking under heavy rain?

Re:Does it double its output ... (4, Funny)

mordenkhai (1167617) | more than 6 years ago | (#22370624)

Only if its Chocolate Rain.

Lots of applications ... (3, Funny)

ScrewMaster (602015) | more than 6 years ago | (#22370174)

A lighter version would be helpful to hikers or soldiers who don't have easy access to electricity.

Sergeant: Private!

Private: Sir!

Seargeant: Walk faster! We're trying to reach HQ.

Re:Lots of applications ... (1, Informative)

hazem (472289) | more than 6 years ago | (#22370570)

Good joke, but just an FYI, privates don't "sir" sergeants, seeing that sergeants work for a living.

(In the US Army, at least, "sir" is reserved for male officers and warrant officers.)

Re:Lots of applications ... (1)

ScrewMaster (602015) | more than 6 years ago | (#22371296)

Yeah, I knew that, actually, but I just woke up.

Re:Lots of applications ... (0)

Anonymous Coward | more than 6 years ago | (#22371770)

Didn't Forrest Gump have a stint in the Army?

Ruuuuuuuuun, fooooooooorrrrrrrreeeeeeeesssssssstttttttt!

Re:Lots of applications ... (1)

eonlabs (921625) | more than 6 years ago | (#22372650)

Those neurotransmitters are a bitch to keep powered all the time. Damn, most of my classmates and coworkers clearly had difficulty with keeping theirs up and running. I'm sure many people can say the same.

Considering the the potential energy stores in... (4, Interesting)

iknownuttin (1099999) | more than 6 years ago | (#22370180)

Walmart customers, I think if we can get them walking with these on, we'll solve all of our energy needs! Think about it. The entire country powered by fat, Cheetoes, Doritoes, Beer, etc.... And, with all of these large folks walking, they'll be in better health and therefore reduce the burden on our health care system ( one of the biggest expenses the Medicare has to deal with is kidney dialysis because folks fry their kidneys from hypertension. ).

Re:Considering the the potential energy stores in. (4, Informative)

ddrichardson (869910) | more than 6 years ago | (#22370394)

A study in Holland [plosjournals.org] disagrees about the savings from obesity reduction:

Conclusions

Although effective obesity prevention leads to a decrease in costs of obesity-related diseases, this decrease is offset by cost increases due to diseases unrelated to obesity in life-years gained. Obesity prevention may be an important and cost-effective way of improving public health, but it is not a cure for increasing health expenditures.

Re:Considering the the potential energy stores in. (1)

snl2587 (1177409) | more than 6 years ago | (#22371076)

But...what if we used them as fuel? I'll bet the researchers didn't consider that!

Re:Considering the the potential energy stores in. (1)

emjay88 (1178161) | more than 6 years ago | (#22374684)

Thanks Denny [tv.com]

Re:Considering the the potential energy stores in. (1)

the_humeister (922869) | more than 6 years ago | (#22371120)

A similar thing is going on with anti-smoking campaigns and mandatory seat-belt laws. With less people smoking, there are less people dying earlier of lung-related illnesses. With mandatory seat-belt laws, we're seeing a decrease in the number of viable organs for organ donation.

Tobacco corps said the same thing. (1)

iknownuttin (1099999) | more than 6 years ago | (#22371126)

I've seen that. It's very interesting. I think what's really ironic is that the tobacco companies have done a similar study (This is the closest I could find after several pages of Google hits [cnn.com] ) a few years ago and it was a PR disaster for them. But now, a similar study regarding obesity has come to the same conclusion that early death benefits society but without the PR disaster. Interesting isn't it?

Re:Considering the the potential energy stores in. (1)

Hal_Porter (817932) | more than 6 years ago | (#22371226)

I've heard smokers make the same argument. By dieing young they save the NHS money in expensive geriatric care. It's probably true, since it's far cheaper to let someone die untreated of something essentially untreatable like lung cancer or a sudden heart attack than it is to keep them alive for years in a old people's home.

Not that the NHS sees it that way of course, they're discussing refusing operations for people who are obese or smokers. [independent.co.uk] . Not all people with self control issues are punished though. Heroin is free on the NHS if you get yourself hooked [bbc.co.uk] .

Mind you most people end up paying for private nursing homes since the NHS ones are so grotty. And if the NHS refuses to pay for parts of your lung cancer treatment, you can't just pay for that part, you need to pay for the whole lot [bbc.co.uk] . So you don't have a choice about paying National Insurance, but they can decide not to pay for drugs that would keep you alive. If you don't like it, you need to pay for the whole cost of the treatment. It's sort of like an HMO that you're legally obliged to contribute to. In fact avoiding National Insurance can lead to prison since it legally considered a tax.

You'd think things like this and the obviously dismal state of NHS dentistry would put Americans off the concept of socialized health care, but quite often they'll joke about British teeth and then enthusiastically advocate it without seeing the link between the two.

Re:Considering the the potential energy stores in. (2, Interesting)

TheLink (130905) | more than 6 years ago | (#22371558)

I'm not a smoker.

But that's why I don't understand why so many of those socialist european countries are so against smoking, when they are so worried about "aging population" and creaking health services.

Sure discourage people from smoking, and educate them on the dangers. But don't make it impossible.

Tax tobacco enough and the smokers pay for their own "funeral" and everyone else's :).

If smokers survive past retirement age, they'll still be paying tobacco taxes. Give the best "donors" a cert of appreciation or something ;).

A lot of the antismoking stats seem to assume that nonsmokers never die. Worse - some even use the potential lost future earnings of a smoker who dies early as a "cost", which is _bullshit_. Smokers dying early means you don't need to support them later. Unless they are dying so early ( <25 ) when they haven't yet fully paid for the cost of bringing them up etc.

Maybe a smoker dying at 40 or 50, from lung cancer might be expensive. But dying from some other cancer is quite expensive too, and if the "nanny state" country has to take care of them from 60 till 80 when they finally die it gets more expensive.

As for obesity. IMO dying from a heart attack isn't that bad a way to go. But diabetes is.

Re:Considering the the potential energy stores in. (1)

edcheevy (1160545) | more than 6 years ago | (#22372222)

I could see where a long term healthy person might cost more than a short term obese person, but did they include the extra taxes and/or health insurance premiums a person might generate if they didn't die of a heart attack at 40?

Re:Considering the the potential energy stores in. (3, Funny)

g0dsp33d (849253) | more than 6 years ago | (#22370544)

I wonder how long until they pair this with a water tight hydration recycling suit and we chase worms in the desert?

Re:Considering the the potential energy stores in. (2, Insightful)

0100010001010011 (652467) | more than 6 years ago | (#22370854)

Walmart shoppers can walk? Most I see park in handicapped and get around on tiny electric scooters.

Re:Considering the the potential energy stores in. (1)

boundary (1226600) | more than 6 years ago | (#22371706)

Perhaps they should therefore invent a dynamo-wired fridge door, beer can ring pull, or perhaps a sofa cushion...

Re:Considering the the potential energy stores in. (1)

iluvcapra (782887) | more than 6 years ago | (#22372410)

In The Dilbert Future, Scott Adams suggested the logical consummation of this, and really the most complelling way of harnessing "stupidity for clean power(tm)".

The proposal is pretty ingenious: First, you build a bunch of large hamster-wheel type contraptions in front of gas stations and convenience stores. The energy generated by people running in the wheels is hooked either to the grid or electrolysis for Hydrogen production. Then, you offer a 10 free lottery tickets per every 15 minutes in the wheel.

Re:Considering the the potential energy stores in. (0)

Anonymous Coward | more than 6 years ago | (#22372732)

The entire country powered by fat, Cheetoes, Doritoes, [...]

"Cheetoes"? "Doritoes"? Dan Quayle, is that you?!

Re:Considering the the potential energy stores in. (5, Interesting)

KefabiMe (730997) | more than 6 years ago | (#22374138)

Actually, there is concern that this device may cause muscles to atrophy. It works by helping slow down your leg during the part of each step where your quadriceps "slow down" your leg. Similar to how electric cars use "regenerative breaking" to slow the car down and gain back energy.

In fact, theoretically when this device gets light and exact enough, walking can take less effort than without the device!

less than one watt for one watt? (1)

GroeFaZ (850443) | more than 6 years ago | (#22370190)

Care to explain how this statement, as it stands, does not conflict with the 2nd law of Thermodynamics?

Re:less than one watt for one watt? (4, Informative)

Burdell (228580) | more than 6 years ago | (#22370214)

It is less than one watt of extra metabolic power when braking. I would assume (without RTFA) that this is analogous to regenerative braking in electric/hybrid cars.

Re:less than one watt for one watt? (3, Informative)

Yetihehe (971185) | more than 6 years ago | (#22371602)

Yes, you are right. This brace helps you to brake your leg, when you straighten it for next step. It uses your lower leg momentum to generate electricity.

Re:less than one watt for one watt? (5, Funny)

maxwell demon (590494) | more than 6 years ago | (#22370226)

Care to explain how this statement, as it stands, does not conflict with the 2nd law of Thermodynamics?

That's simple: They violate the first law of thermodynamics, not the second one.

Re:less than one watt for one watt? (2, Informative)

TheEmptySet (1060334) | more than 6 years ago | (#22370242)

It generates energy as the knee is using energy to slow your downward motion, hence the statement "less than one watt of EXTRA metabolic power for each watt of electricity".

Re:less than one watt for one watt? (1)

vertinox (846076) | more than 6 years ago | (#22370268)

Gravity.

Walking and running is a controlled form of falling forwards.

Maybe .75 watt of metabolism to lift foot up met by .75 created by gravity where .5 is wasted due to heat and other forces leaving 1 watt left over?

Of course someone might be calculating a metabolic watt different from a plain old electrical watt for some reason.

Re:less than one watt for one watt? (1)

jadavis (473492) | more than 6 years ago | (#22372158)

Walking and running is a controlled form of falling forwards.

I've always wondered what people mean when they say that. Is standing still a controlled form of falling as well? What if you walk sideways, what's that? It seems to me that lying down must be a controlled fall, because you actually end up at a lower potential energy state, without ever losing control of the states in between.

So is there some kind of scientific basis for your statement? Or is it just one of those things that one person says, and everyone else keeps repeating? Or is it just a statement that is trivially true, such that it could be applied to anything ("swimming is a controlled form of sinking", "baking is a controlled form of burning") and thus has no meaning at all?

Re:less than one watt for one watt? (2, Informative)

heinousjay (683506) | more than 6 years ago | (#22373506)

They're all controlled falls. Try doing any of those things without using gravity.

Re:less than one watt for one watt? (1)

jadavis (473492) | more than 6 years ago | (#22374182)

Then anything that depends on gravitational force is a controlled fall?

If that's the case, then calling walking a "controlled fall" is meaningless (or nearly so).

Well... (5, Funny)

vertinox (846076) | more than 6 years ago | (#22370192)

Thats neat. But wouldn't it be more efficient for us slashdotters if it was put on our arms... Depending on which one is using the mouse... Or... Umm... The one not holding the lotion bottle?

Re:Well... (0)

Anonymous Coward | more than 6 years ago | (#22372374)

You fool! That would only worsen the strong-right-arm syndrome!

Perpetuum mobile? (1)

maxwell demon (590494) | more than 6 years ago | (#22370200)

In the mode in which the brace is only activated while the knee is braking, the subjects required less than one watt of extra metabolic power for each watt of electricity they generated.

Sounds like a violation of energy conservation.

Re:Perpetuum mobile? (5, Informative)

antifoidulus (807088) | more than 6 years ago | (#22370494)

Someone needs to work on their reading comprehension skills:

In the mode in which the brace is only activated while the knee is braking, the subjects required less than one watt of extra metabolic power for each watt of electricity they generated.(emphasis mine)

That means that the system captures some of the energy that would normally be "wasted" and converts it into electricity instead....

Re:Perpetuum mobile? (1)

jumperboy (1054800) | more than 6 years ago | (#22371860)

I wonder how much energy would be generated by a hip brake as I perfect the ass groove in my office chair all day...

Re:Perpetuum mobile? (1)

Snuhwolf (1105289) | more than 6 years ago | (#22373534)

Why not self contained hydraulic pumps in the heels of army boots that drive a small turbine when weight is transfered to the heel?
That would require no extra energy expenditure. Assuming of course they were being worn on earth where theres some gravity...

Re:Perpetuum mobile? (1)

fabs64 (657132) | more than 6 years ago | (#22374458)

There was an article about doing just this a while back actually.

From memory they had to use piezo's so the energy generated wasn't that great, still interesting though.

Re:Perpetuum mobile? (1)

MrMr (219533) | more than 6 years ago | (#22370500)

No, the university press release claims that the energy is collected from otherwise dissipated heat.
Sounds more like Maxwell demon ...

Re:Perpetuum mobile? (2, Informative)

KiloByte (825081) | more than 6 years ago | (#22371392)

Not exactly. The Maxwell demon takes what already is heat, these braces take what would turn to heat if unharvested.

In other news: (3, Funny)

imsabbel (611519) | more than 6 years ago | (#22370204)

Knee Brace makes walking harder - Segway sees potential market opening

Re:In other news: (1)

Deadstick (535032) | more than 6 years ago | (#22371100)

Segway sees potential market opening

Not Segway, Nautilus. Put an assembly of these suckers on all your major joints, dump the generated power into a resistor, and you have an exercise machine.

rj

Re:In other news: (0, Redundant)

KefabiMe (730997) | more than 6 years ago | (#22374160)

This device theoretically can make walking easier! It works by helping slow down your legs during each step. But the key point is that it only turns on during the part of your step where your muscles would be trying to slow down your leg anyway! (Similar to regenerative braking in electric cars.) So technically, this will make walking take less effort, not more!

Metal Gear? (1)

AbsoluteXyro (1048620) | more than 6 years ago | (#22370218)

At least this finally makes some sense out of Naked Snake's whole "walk around to recharge the battery" thing. Does this device generate enough power to operate a soliton radar?

Re:Metal Gear? (1)

pizzach (1011925) | more than 6 years ago | (#22370996)

I do believe I remember someone saying on slashdot.jp yesterday something about 5 min of walking = 1 hour of battery time for a standard cell phone. So I would say probably.

These stories are getting old. (4, Funny)

moseman (190361) | more than 6 years ago | (#22370282)

When someone comes up with one that can convert talking into usable energy, let me know. I have several women in my office that could generate enough power to light a small country!

Re:These stories are getting old. (0)

Anonymous Coward | more than 6 years ago | (#22370526)

You see, women are a lot like cars. When you've had your fill of talk radio, volume at max and sometimes in full stereo in each ear, and the car itself sucks more of your paycheck in maintenance and fuel than your return investment on driving pleasure:

A. Leave the rusted VW Beetle stranded on the highway.
B. Frequent swank Las Vegas "dealerships", test driving the rentals every other weekend.
or
C. As an anniversary gift, swap out the stock tires with some 20" rims to rub your hands all over with.

Re:These stories are getting old. (0)

Anonymous Coward | more than 6 years ago | (#22371470)

What is this, 1940?

Re:These stories are getting old. (0)

Anonymous Coward | more than 6 years ago | (#22374796)

What are you, a faggot?

Walk across USA and lose 180 pounds (1)

spineboy (22918) | more than 6 years ago | (#22373960)

Walking/running roughly burns one calorie per pound per mile. You need to burn roughly 3500 calories to lose a pound. The average basal matabolic rate in an average person burns about 1500 calories So a 330 pound person, could subsist on vitamins and water, and walk across the entire USA, and arrive at a svelte 120 pounds.
I picked a reasonable pace of 3 MPH for 15 hours a day, which would get you across the country in 66 days, using an additional 28 pounds for the basal metabolic rate.

they had a bit about this on NPR (5, Informative)

Raleel (30913) | more than 6 years ago | (#22370318)

it's so heavy right now because they made all the parts easily replaceable to the scientists working on it. The scientist they interviewed on it also mentioned that if you stop wearing it, you tend to swing your leg harder for the first 3-10 steps, unaccustomed to the now-unpresent braking by the device. Really neat idea... while it makes sense to me, I didn't realize we actually braked our legs as we walked forward.

Re:they had a bit about this on NPR (1)

gotzero (1177159) | more than 6 years ago | (#22370990)

Maybe it could be used to build muscle too. Go for a jog down a hill and you will feel your legs braking quite a bit. Hopefully they are able to make it a little less intrusive, and very inexpensive.

Exercise Power Plants (1)

Doc Ruby (173196) | more than 6 years ago | (#22370360)

Someday all that exercise equipment in gyms will reclaim all their expended human energy into powering their own devices. Since even top performers like Lance Armstrong produce only 500W for under 20min [active.com] , maybe we can just hope that exercisers can work off their lighting bill, if not heat their showers.

Hikers with a body suit, though, might be able to cook their dinner.

Re:Exercise Power Plants (1)

Babu 'God' Hoover (1213422) | more than 6 years ago | (#22370580)

Someone who exercises 1,000-1,200 Calories(that's a big C so we're talking 1.0-1.2 million one ml by one degree calories or 20 litres by 50 degrees) makes plenty of heat for a nice hot shower. For me this is about an hour on the stair climber or an hour and a half in the pool. As far as output to the machine it's only 2-250 Watt-hour but the heat energy is all there. Aside from getting ones exercise by swimming, I don't know of a good way to capture all that heat.

Re:Exercise Power Plants (1)

EaglemanBSA (950534) | more than 6 years ago | (#22370598)

Actually, most gyms already do this - if you haven't noticed, most modern gym equipment (bikes, rowing machines, etc.) doesn't start up until you start using it.

Now, if we could find an efficient way to extract the extra heat produced during exercise from the human body, that would be awfully cool - the human would be able to perform longer, and the heat could be used for something useful. Turns out the human body is a terribly inefficient heat engine - according to NASA SP-3006 (I research human power as a Mechanical Engineer), a human produces almost twice as much energy in waste metabolic heat that the body has trouble getting rid of as they do mechanical work.

Re:Exercise Power Plants (2, Informative)

Mendenhall (32321) | more than 6 years ago | (#22370856)

On the efficiency of the human body as an engine, the number you quote is about right. However, assessing that as a terribly inefficient heat engine is a bit odd.

A really well-tuned automobile engine, running on pre-refined fuel, might get 40% thermal efficiency or so. The human body, of course, starts with rather unrefined fuel (food, to the non-techie :-) ), runs all the necessary chemical conversion machinery, and produces its output. It also expends a lot of energy in self-repair and maintenance, which for your car is separate. And if your car had to provide enough power for all the computational work we are doing, too, it would further increase the overall energy budget.

A full-cycle efficiency of the 33% or so (assuming your 2:1 ratio of waste heat to output) seems very good. Almost all the fuel conversion techniques we have (oil refining, fermentation to convert the stuff we eat to ethanol, coal gasification, etc.) lose more than this, I suspect.

Re:Exercise Power Plants (1)

Doc Ruby (173196) | more than 6 years ago | (#22370870)

Gyms have lots of lights that are on even when the gym is empty, or when people are taking a rest. I think their body work could power those lights pretty well, offloading from the grid quite a bit.

Maybe there's a way to capture that waste body heat to heat up the water in the showers that people take after exercising. If the mechanical work is captured efficiently as power for lighting, then those gyms could nearly disappear from the grid, except as backup. The elevators in NYC gyms probably keep the energy budget in the black, though. Maybe they should switch to stairs, or manual elevators run by "stationary" bikes mounted in them.

Umm likely no (1)

way2trivial (601132) | more than 6 years ago | (#22371964)

Re:Umm likely no (1)

Doc Ruby (173196) | more than 6 years ago | (#22372124)

How does an article demonstrating that people are actually doing this show that people likely won't do this?

Re:Exercise Power Plants (2, Funny)

snl2587 (1177409) | more than 6 years ago | (#22371604)

Now, if we could find an efficient way to extract the extra heat produced during exercise from the human body...

I have an idea: we could put the humans in a little shell that captures their heat energy as they go about their lives. Come to think of it, it would make more sense if they were sedentary....and we could feed them through tubes....and make them think they were living free....oh, nevermind.

None shall pass. (1)

djupedal (584558) | more than 6 years ago | (#22370372)

Oh. Oh, I see. Running away, eh? You yellow bastards! Come back here and take what's coming to you. I'll bite your legs off!

Re:None shall pass. (0)

Anonymous Coward | more than 6 years ago | (#22373218)

http://xkcd.com/16/ [xkcd.com]

Enough!

Exercise plants! (1)

maxwell demon (590494) | more than 6 years ago | (#22370462)

I've found the solution to several problems at once: Exercise plants!

This will
  • generate jobs for unlearned workers, thus reducing unemployment
  • increase the health of those workers
  • reduce the reliance on oil
  • fight global warming, because the energy comes from food, that is, from regenerative sources


SCNR :-)

Compare against bicycle not hand crank ... (1)

AHumbleOpinion (546848) | more than 6 years ago | (#22370472)

In the mode in which the brace is only activated while the knee is braking, the subjects required less than one watt of extra metabolic power for each watt of electricity they generated. A typical hand-crank generator, for comparison, takes an average of 6.4 watts of metabolic power to generate one watt of electricity because of inefficiencies of muscles and generators.

That is a bogus comparison, the arm and leg muscles are too different. A fair comparison might be bicycle based generator. Junk like this makes my think hype not science. Well less than one watt in and a full watt out makes me think not science as well.

Re:Compare against bicycle not hand crank ... (0)

Anonymous Coward | more than 6 years ago | (#22370674)

That is a bogus comparison, the arm and leg muscles are too different. A fair comparison might be bicycle based generator. Junk like this makes my think hype not science. Well less than one watt in and a full watt out makes me think not science as well.

...and uneducated drivel like yours makes me wonder why I read slashdot.

Re:Compare against bicycle not hand crank ... (1)

gbjbaanb (229885) | more than 6 years ago | (#22370874)

Well less than one watt in and a full watt out makes me think not science as well.
statements like that make me think: try actually reading the article instead of just looking at the pictures.

the subjects required less than one watt of extra metabolic power for each watt of electricity they generated.

Re:Compare against bicycle not hand crank ... (1)

AHumbleOpinion (546848) | more than 6 years ago | (#22371166)

"Well less than one watt in and a full watt out makes me think not science as well."

statements like that make me think: try actually reading the article instead of just looking at the pictures.

the subjects required less than one watt of extra metabolic power for each watt of electricity they generated.


Try thinking harder. Your logic seems to assume that there is sufficient kinetic inefficiency to make up the difference. While this may be true for cars it is unlikely for a biological organism that has gone through millions of years of evolution optimizing walking efficiency. Also measuring power via respiration is highly suspect. It only measures total energy and does not measure shifts of energy from one bodily function to another. For example was energy diverted from digestion?

Re:Compare against bicycle not hand crank ... (1)

sssssss27 (1117705) | more than 6 years ago | (#22370892)

I think it was a fair comparison. How portable is a bicycle based generator? That and I imagine more people have been exposed to hand crank generators than they have bicycle based ones. It also doesn't say the device takes in less than one watt for every watt it puts out. It says the device required less than one watt of extra effort on the part of the wearer to get one watt out. In other words it's capturing some of the energy that would have been wasted anyways.

Re:Compare against bicycle not hand crank ... (1)

AHumbleOpinion (546848) | more than 6 years ago | (#22371052)

I think it was a fair comparison. How portable is a bicycle based generator?

Smaller than a hand crank, and they generate enough energy to power a headlight. And that was with 1970s tech.

Re:Compare against bicycle not hand crank ... (1)

sssssss27 (1117705) | more than 6 years ago | (#22371136)

Really? I could be mistaken then. I would have assumed the pedal on a bicycle based generator would have been bigger than the whole unit for a hand-crank one.

Re:Compare against bicycle not hand crank ... (1)

AHumbleOpinion (546848) | more than 6 years ago | (#22371312)

Really? I could be mistaken then. I would have assumed the pedal on a bicycle based generator would have been bigger than the whole unit for a hand-crank one.

One implementation of the generator is a device that makes contact with a wheel and spins as the wheel rotates. These are very small devices. With regard to making a bicycle a stationary generator a hole and some minor carpentry skill will accomplish that. However I think that is a tangent. If you are going to walk to generate power you could probably bike.

Re:Compare against bicycle not hand crank ... (1)

AHumbleOpinion (546848) | more than 6 years ago | (#22371490)

It also doesn't say the device takes in less than one watt for every watt it puts out. It says the device required less than one watt of extra effort on the part of the wearer to get one watt out. In other words it's capturing some of the energy that would have been wasted anyways.

Their measurements are naive. Respiration only indicates total energy consumption. It does not indicate a reallocation of energy within the body, for example digestion may have been slowed to provide additional energy. Furthermore what is the comparison of energy savings by reducing biological arresting of forward motion against the bodies own recapturing of energy and the additional energy required to operate without this evolutionary recapture system and the additional energy need to carry this apparatus around.

This device seems highly useful, but "free" with respect to bodily energy is a bit hard to believe. It is far easier to believe we have an incomplete picture.

At long last (1, Funny)

Anonymous Coward | more than 6 years ago | (#22370498)

A use for Heather Mills! [wikipedia.org]

Anybody got a whip?

You can get hurt by something like that (4, Insightful)

roman_mir (125474) | more than 6 years ago | (#22370588)

As a guy who has had constant pain in his knees for the past 7 years, I am warning you that something like that may permanently damage your knee joint by simply forcing a minuscule change to the way your knee rotates while walking. I mean if unfitting shoes can hurt your knee, foot and hip joints (and they can) then this device may certainly hurt all of those joints as well if it forces you to change the way your legs are naturally moving.

Don't damage your joints, the pain may last for the rest of your life.

Re:You can get hurt by something like that (0)

Anonymous Coward | more than 6 years ago | (#22371160)

Don't damage your joints, the pain may last for the rest of your life.


While we're being cautionary here let me just say this to the young'uns:

Protect your hearing.

Seriously. Don't use fireworks in confined spaces, wear hearing protection when shooting and when operating power tools for extended period, and turn down that music.

Otherwise you might get to enjoy tinnitus [wikipedia.org] for the rest of your days. And by enjoy I mean experience difficulty hearing over the persistent ringing in your ears as well as experiencing occasional difficulty falling asleep due to the #&%@*!% ceaseless ringing in your ears.

Re:You can get hurt by something like that (1)

justinchudgar (922219) | more than 6 years ago | (#22371514)

I've got a messed up knee; and, I wear a brace to do any serious hiking or similar activity. Since I've already got the damn itch, sweaty, annoying thing on; it might as well serve two functions instead of just one. Power and joint stabilization seem like a nice deal for those who need the stabilization in the first place.

For those whose knees are fine, however, it seems likely that the discomfort of any brace will outweigh the minimal juice provided. Carrying a supply of spare NiMH or other rechargeable batteries in your backpack or camera bag is not a great burden for an equivalent amount of juice. If you compare the weight of the food and water needed for a day of hiking compared to the weight of the batteries needed to run a GPS, camera and cell phone, the juice is negligible.

Re:You can get hurt by something like that (2, Funny)

Cousin Scuzzy (754180) | more than 6 years ago | (#22371520)

As a guy who has had constant pain in his knees for the past 7 years, I am warning you that something like that may permanently damage your knee joint by simply forcing a minuscule change to the way your knee rotates while walking.
The article states that the brace is activated only while the knee is breaking. Of course it's going to be painful if your knee is breaking. Duh...

What's that? Oh, braking...

Never mind.

I just like it because ... (1)

John Jorsett (171560) | more than 6 years ago | (#22370602)

it makes us look more like the Borg.

Slashdot is losing its edge (0, Troll)

mark99 (459508) | more than 6 years ago | (#22370648)

Yawn - the Economist had an extensive article on this last week.

It is sad when we get scooped by a large conservative economic journal that is only periphally concerned with technology.

If the fanboys on this site could focus on posting something besides "Linux is better than evil Microsoft" we might get Slashdot back to being the premier site for propagating techy news for geeks.

Re:Slashdot is losing its edge (1)

SlashWombat (1227578) | more than 6 years ago | (#22370832)

Your joking? A one watt solar cell would be a lot less intrusive.

Might I suggest the authors had this device strapped somewhere else, and that they now all need glasses. (As per the old joke ... can I do it until I need glasses.)

Bad Idea (1)

PolarBearFire (1176791) | more than 6 years ago | (#22370686)

Really horrible idea, good knees are what people miss the most as people get older. I wouldn't want to trade 10 years of good knees just charge up my cell phone. Furthermore if I was a hiker or soldier walking all day, I wouldn't want extra stuff attached to my leg actually impeding my leg movements for a few extra watts of electrical energy.

Re:Bad Idea (1)

greyhueofdoubt (1159527) | more than 6 years ago | (#22371030)

I wouldn't be so quick to dismiss this gadget. There is a good chance that the stabilizing function of this generator far outweighs the extra pressure exerted on the joints.

>>Furthermore if I was a hiker or soldier walking all day, I wouldn't want extra stuff attached to my leg actually impeding my leg movements for a few extra watts of electrical energy.

Would you rather have 10 pounds of batteries to power your radio, stove, lights, PSP, etc., or 1-2 pounds of knee brace that actually stabilized your gait? I AM a soldier and a hiker, and I would pay this device's weight in gold if it was as reliable and lightweight as they make it out to be. OK- maybe not gold, but some metal in the $100/lb area.

-b

There's an abundant source of power here (2, Funny)

thewils (463314) | more than 6 years ago | (#22370754)

If you could develop a smaller one that fits over a beer-drinker's elbow.

Or how about a micro one that works off a woman's jaw muscles? No, wait, that means their cellphone batteries would never quit. Yikes!

how does this work on hills? (1)

rubah (1197475) | more than 6 years ago | (#22371072)

My campus is incrediably hilly, and there are some hills where it is just more comfortable to run down. Would this thing have any effect on steep hills, I wonder?

I don't know much about how the knee functions, but it seems like I do a lot more of this 'braking' in the last 50 ft of my trek to class than anywhere else

Interview with inventor (1)

peterjt (50113) | more than 6 years ago | (#22371078)

This weekend, the CBC radio program Quirks and Quarks had an interview with Dr. Max Donelan. You can listen to the interview in either ogg or mp3 format at http://www.cbc.ca/quirks/archives/07-08/feb09.html [www.cbc.ca]

And the best way to use this electricity is... (1)

k2backhoe (1092067) | more than 6 years ago | (#22371084)

to power an exoskeleton. The power source is right where you need it and you no longer have to carry those heavy batteries!!

Re:And the best way to use this electricity is... (1)

greyhueofdoubt (1159527) | more than 6 years ago | (#22373812)

Wouldn't the exoskeleton be useful in large part for supporting and actuating the legs (In order to carry a heavier load)? It would be like like hooking up a generator to an electric motor. At best you could recover some of the energy used for braking or slowing, but you would still need batteries.

-b

And the best use of this enegy is ... (1)

k2backhoe (1092067) | more than 6 years ago | (#22371178)

to power the exoskeleton. Power is generated just where you need it, and you don't have to carry any big heavy batteries!

Treadmill = Energy, this is my question . . . (1)

corifornia2 (1158503) | more than 6 years ago | (#22371316)

I go to the gym a lot and there are like 200 people on treadmills when I go. Does anyone know what stops us from generating power from the hamster people?
IF this idea is feasible then, PATENT PENDING (C) 2008 ME

Re:Treadmill = Energy, this is my question . . . (1)

BeanThere (28381) | more than 6 years ago | (#22372534)

Like anything that generates power humans need an energy source / fuel, our "fuel" is food, so one factor in the cost (energywise and financially and resource-wise) of producing and distributing that fuel if one wants to make any meaningful comparisons.

Nonetheless you are looking at *a* possible power source, sure.

If someone burns fat to run that treadmill then you're using stored energy, like a battery. If someone keeps thin then they have to eat more to run on that treadmill. Of course exercise is good for you so there's nothing wrong with that to a degree, but if you only end up with a situation where people are just eating more in order to generate electricity via the gym you might not be better off (e.g. it might be more efficient to use the extra land required for say small solar plants instead). Still, it would be better not to waste the treadmill energy which people are going to expend anyway.

Re:Treadmill = Energy, this is my question . . . (1)

greyhueofdoubt (1159527) | more than 6 years ago | (#22374062)

This is really meant more as a point-of-use generator, not something that would be connected to the grid. The most efficient source of power would be upcoming super-capacitors, but there is a point beyond which carrying additional units would return less benefit- fatigue, primarily, would direct how many units could be carried.

This knee generator is meant to replace bulky and expensive batteries for people not connected to the grid. This would be useful in the field as well as in normal civilian life, where it's not always convenient to be sitting next to a power outlet.

An average person walking slowly will burn about 200 kilocalories per hour. To generate one watt/hour (creating one watt for one hour) a person would expend 860 calories. Since this device is using the generator as a brake on the leg, a person should need less than the 860 calories to actually create the watt-hour. Even if we go with the full 860 calories, we're only looking at 200.86 kilocalories. That could be restored to the body with one tenth of an MRE or a pack of M&Ms or a muffin or something. A watt-hour is not a terribly large amount of energy to generate; it only seems like a lot because when it's used inefficiently, it won't get much work done.

As I said in another post, I'd pay a healthy sum for this device for field use.

-b

Gitmo (1)

PoopDaddy (1064616) | more than 6 years ago | (#22371508)

Hey great, now Guantanamo detainees can electrocute their own genitals just by being marched around!

BRILLIANT! (1)

HeavensFire (1161917) | more than 6 years ago | (#22371614)

who would have thought that the six million dollar man could be the answer to the world's energy crisis?

Do do do do do! Ba ba ba ba ba!

Audio interview about the "Energy Brace" from CBC (4, Informative)

ClarkMills (515300) | more than 6 years ago | (#22371660)

The article with graphic:

    http://www.cbc.ca/quirks/archives/07-08/feb09.html [www.cbc.ca]

The Interview (in OGG & MP3 formats) :

    http://www.cbc.ca/quirks/media/2007-2008/ogg/qq-2008-02-09_01.ogg [www.cbc.ca]
    http://www.cbc.ca/quirks/media/2007-2008/mp3/qq-2008-02-09_01.mp3 [www.cbc.ca]

Crackpots and Nutjobs (0)

Anonymous Coward | more than 6 years ago | (#22372140)

the subjects required less than one watt of extra metabolic power for each watt of electricity they generated.

Perpetual motion machines are impossible! How many time we gotta tell ya? Either the magnets eventually lose their magnetic "charge", or you finish digesting the potato and have to eat another one!

The ER/EI is all wrong (1)

Ralph Spoilsport (673134) | more than 6 years ago | (#22372340)

Powering the device requires using calories you eat. However, every calorie you eat requires 10 calories of fossil fuel to get it in your mouth.

As a consequence, whatever energy is used to power such a device needs to be measured against that yard stick.

It's kind of like using an electric stove. One can (for example) burn natural gas to power a generator to power your stove, with, at best 20% efficiency (the nat gas turbine isn't super eficient, and then its dumped into electric lines that are lossy, and then it goes to your stove, which also has loss.) The result? You're beter off burning nat gas directly to cook your food...

Same with this gizmo. You;'re better off using rechargable batteries...

RS

Re:The ER/EI is all wrong (1)

Stray7Xi (698337) | more than 6 years ago | (#22374656)

Powering the device requires using calories you eat. However, every calorie you eat requires 10 calories of fossil fuel to get it in your mouth.
That may be true for the average person. What if I grow my own food with no fossil fuels. Am I better off burning the food or eating the food and using tech like this? I guess that depends on what the food is. But this also has the side effect of extra exercise.

Re:The ER/EI is all wrong (1)

BotnetZombie (1174935) | more than 6 years ago | (#22374682)

Exercise requires using calories already eaten. You opposed to that too? If you don't burn those calories, they end up as huge energy stores wrapped around your body. I'd be glad to give up those love handles if it would keep my mobile alive for longer. Or maybe I'm missing some obvious sarcasm here?

A kid in New Zealand invented this last year (1)

dandman (125459) | more than 6 years ago | (#22372838)

On a kids show called "Lets Get Inventin", Alex Drinkwater built exactly this device [tvnz.co.nz] - and got a full working prototype going.
As you can see by the picture (half way down this article [idealog.co.nz] ) direct image link [idealog.co.nz] the design is not only identical - it's BETTER with a built-in cellphone carrier! Somebody, give the kid his patent!

More importantly, is it comfortable? (1)

Lead Butthead (321013) | more than 6 years ago | (#22373106)

No one will buy into one of these if it isn't comfortable to wear.
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