Latest "Green" Power Generation — Your Feet

gbjbaanb writes "Remember those ideas that suggested hooking gym machines to the power grid? Well, the Times is reporting that something like this to harness free energy is about to become a reality — the footfall of trudging shoppers is to become the latest source of emission-free energy. 'Engineers who have modelled the effects of the technology at Victoria Underground station in central London have calculated that the 34,000 travellers passing through every hour could power 6,500 lightbulbs. ... The plans for heel-strike generation follow successful trials last year at a bridge in the Midlands where generators converted energy from trains passing above into electricity powering a flood detector.' Possibly the most important thing for the readership is at the end: 'There could also be a range of domestic uses, for example powering iPods by plugging them into batteries placed in the owners' heels, using technology which is already available.' Obviously you'd have to get up and walk around, but, as they say, it's the thought that counts."

There is no free lunch

[Omniscious]

As well as no free energy.

Re:There is no free lunch

[dougmc]

Energy from the sun is approximately free, especially when you put your solar panels on top of building and such rather than in fields ... but I digress. (I said approximately -- the solar panels are not free, and neither are any other components or their maintenance.)

But as for free energy -- this is not it. By putting generators in the ground that are moved by people walking on them, it will make it harder to walk. I don't know the specifics, but I'm guessing that parts of the floor will move up and down a little as people walk on it, probably a few milimeters. It might be somewhat akin to walking on sand -- and I have to wonder what it would do to a wheelchair.

This might be practical if you're in a remote location where electrical power is unavailable and you only need a little -- but beyond that, the solution seems worse than the problem. (And really, solar power is more practical for remote areas where you need only a little power.)

Re:There is no free lunch

[gbjbaanb]

by people walking on them, it will make it harder to walk

I remember some adverts for training shoes that had fluid capsules inside them to reduce stresses on your joints (or something, probably just marketing). People bought them but didn't complain they were difficult to walk in. If the generation systems are of the same order, then I can't see a problem.

I imagine it would cost a fair bit to install, but there's paths everywhere, whereas solar panels have a limited amount of area they can be installed on. Also, these wouldn't require the noxious chemicals solar panels are made of, and wouldn't require as much maintenance (I think).

For other areas, I thought bridges etc had to have soem 'squidginess' to them, or the traffic riding on them would quickly shake it to bits. As the article said, this principle also applies to antennas that wave in the wind, so its not just going to be used in every pavement in the world.

Re:There is no free lunch

[smaddox]

Also, these wouldn't require the noxious chemicals solar panels are made of, and wouldn't require as much maintenance (I think).

Noxious chemicals?

Silicon, and trace amounts of boron and phosphorous are noxious? You need to go back to chemistry class. Not only is silicon one of the most abundant elements on earth, it is one of the least harmful to humans.

Also, solar cells don't really require maintenance. You would want to clean them occasionally to get optimal power, but that involves spraying them off with a hose. That is the beauty of photovoltaics - there are no moving parts to break.

Re:There is no free lunch

[gbjbaanb]

Me? You're the one that needs to go back to eco-warrior class.

IIRC it was cadmium used in the manufacture that made solar cells not as green as they could be.


A quick google says
However there are many environmentalists and some scientists that are worried about the potential negative impact of solar cells (photovoltaic technology). This is because manufacturing process of photovoltaic cells needs toxic metals such as mercury, lead and cadmium

Still, I think its better than coal-fired power, but don't think any green energy generation is the perfect answer to all problems.

Re:

[Tweenk]

Commercial PV cells are not made of doped silicon as you seem to presume. They are made of cadmium telluride. This thing IS noxious: Wikipedia is your friend. [wikipedia.org] Silicon cells are only used in laboratories, because for now they are much more expensive.

Additionally, silicon is abundant on Earth, but it doesn't mean it's cheap. Obtaining semiconductor grade silicon from sand or silicates is not a trivial process, and this is why it's still very expensive despite its broad usage.

Re:There is no free lunch

[tehdaemon]

Yes, Wikipedia is your friend [wikipedia.org], but you have to know how to use it. Most solar cells are not cadmium telluride.

From this wikipedia link,

First-generation photovoltaic cells (also known as silicon wafer-based solar cells) are the dominant technology in the commercial production of solar cells, accounting for more than 86% of the terrestrial solar cell market.

T

Re:

[vimm]

That would be smaddox's edit on Sunday June 8, at 5:14 pm

Re:

[tehdaemon]

Haha - That isn't quite what I had in mind when I mentioned "how to use it". I guess I did set myself up for that though.

smaddox, whoever (s)he is, edited the next paragraph.

T

Re:There is no free lunch

[TubeSteak]

I remember some adverts for training shoes that had fluid capsules inside them to reduce stresses on your joints (or something, probably just marketing). People bought them but didn't complain they were difficult to walk in. If the generation systems are of the same order, then I can't see a problem.

I read an article (I can't find it, but I'm sure someone will pull it up) where they discussed the issues around cushioning in shoes.

What they found is that your body is used to a certain 'feel' from the ground when you walk. It turns out that more cushioning = more stress on your joints, because your body notices the lack of pressure & compensates with harder heel strikes.

The article tied all this into walking barefoot and some shoes that were about as close to walking barefoot as you can get.

Anyways, the moral of the story is that you do work harder with cushioned shoes and they're not good for the health of your feet & lower joints.

Re:There is no free lunch

[maxume]

Probably:

http://nymag.com/health/features/46213/ [nymag.com]

Re:There is no free lunch

[zippthorne]

W=f*d

In the case of the shoes, work done compressing the cushion approximately come back on the up-stroke. It's fairly conservative (in the physics sense). You'll find that if the shoes had tiny holes in the cushions, it'd be quite a bit harder to walk in them, especially if they had a lot of vertical play. The difference between a spring and a shock absorber.

Re:

[Malekin]

The thing about shoes is that while they absorb some energy, they're springy and (good shoes) largely give it back to you when you're lifting your foot. Tiles that absorb energy and don't give it back will indeed make it harder to walk. Probably something akin to walking up a slight incline.

Re:There is no free lunch

[Deadstick]

Probably something akin to walking up a slight incline.

And that would be bad for the typical obese American or Brit how?

rj

Re:

[dougmc]

If you make walking harder, fewer people will walk.

freeking obesity epidemic

[Anonymous Coward]

Most western and industrialized nations people need all the extra exercise they can get. (I said most, not all, some people actually stay in shape, most do not, go ahead, look around you) I think the artificial urban power sucking islands could use around a few million of these generators, help to walk off some of that lard and get some practical benefit from it. I already see those ridiculous belching buses that they praise as mass transit stopping every couple hundred of feet. Egads people can't even walk beyond that? Then they go sit on their asses all day long at some office. Jeebus, how wuss can you get? "OMG it feels like walking on sand! I might get the swooning vapors!"

Re:

[Kjella]

I already see those ridiculous belching buses that they praise as mass transit stopping every couple hundred of feet. Egads people can't even walk beyond that?

Of course they could. But I find the ability to take small trips one of the big advantages of public transportation (got a monthly card so doesn't cost anything extra). Take a few stops from work, go for a walk in the park (much nicer than sidewalks). Take a few more stops, go to a store. Take a few more stops, visit a store in the other end of the city center. Take another few stops and meet some friends at a pub. Not to mention, drink a few beers and take it all the way home. Car user? Well, there's park

Re:

[tverbeek]

The United States has vast, largely-untapped energy reserves stored in the fat cells of its population. If we would start putting this to use for transportation (walking, bicycling, skateboarding, whatever) it would not only reduce our dependence on overseas petroleum, it would reduce the amount we spend on health care. No new technology required.

At 5'10" and 210lbs I'm no fitness freak. But by biking and walking whenever practical, and using the car only when I have to, I go through only about 100 gall

Re:There is no free lunch

[sentientbeing]

Youre right.

I remember this being debunked using basic energy estimates and calculations last year by The Register.

http://www.theregister.co.uk/2007/07/30/all_the_power_they_would_ever_need/ [theregister.co.uk]

Re:

[ma1wrbu5tr]

Victoria Underground station in central London

Um... in this case, I don't think sunshine is something you can count on. This is true of many places.

In the United Kingdom the frequency of rain [wikipedia.org] driven into the
country by the south-western trade winds following the warm gulfstream
currents. Areas along the western coasts can receive between 1016 mm
(40 inches, at sea-level) and 2540 mm (100 inches, on the mountains) of
rain per year.

I live in the middle of a temperate rainforest right here in Washington state. Solar panels simply would not work very efficie

Re:

[aproposofwhat]

When they invent a means of generating power from the pressure of my fat overfed arse on the chair, or from the movement of the TV remote, wake me up.

Otherwise, I'm Mr Couch Potato(head).

:P

Re:

[Thelasko]

By putting generators in the ground that are moved by people walking on them, it will make it harder to walk. I don't know the specifics, but I'm guessing that parts of the floor will move up and down a little as people walk on it, probably a few milimeters. It might be somewhat akin to walking on sand -- and I have to wonder what it would do to a wheelchair.

The cushioning in your shoes already absorbs energy while you walk. You don't mind because it reduces the stress on your joints. The air pockets in your Nikes get slightly warmer when you land on them. The idea is to simply harness that energy.

Where you have a problem is when the owners of these electricity generating floors get greedy. They optimize the floor to generate the maximum amount of electricity without regard for how it effects the people walking on it. Now it feels like walking on sand.

Basic Physics

[EgoWumpus]

You're entirely wrong, I suspect.

The floor moves up and down regardless. Different surfaces will move different amounts based on the type of surface. If you stand on a bamboo pole floor, for instance, you can expect it to flex a lot. If you stand on a concrete floor, it will flex only a tiny amount. It still flexes, though, still moves; that's what causes concrete to crack over time.

Now, for strong surfaces this movement might translate to a very low-level vibration - unnoticeable to you. But it's absence

Re:

[dougmc]

And you're partially wrong.

You're right that all surfaces move to some degree, and some move more than others. Where you're wrong is that most surfaces return most of that energy when they bounce back. Sure, there's some energy lost, but in most cases most of it's returned.

Sand is a case where most of that energy is not returned, and it's very tiring to walk on sand. Ditto for non-packed snow.

Ultimately, it's not going to be practical.

Doing some simple math, let's say that you have 10 1

Re:

[EgoWumpus]

I fear that arguing practicality is never something that is worthwhile engaging in when talking about emerging technologies. Chances are that only the very inventive or the very expert will be able to either, respectively, find the way to make it cost-effective or declare something actually infeasible.

To some degree, it's just a matter of numbers. If I have SuperDuperCrete, a concrete alternative that converts vibration to electricity but in all other ways is exactly like concrete, including cost - well, c

Re:

[dougmc]

The smaller the deflection, the less power generated. If it's hundredths of a millimeter, then you'd be right -- nobody would notice. But on the other hand, the energy generated would be insignificant.

Re:

[dougmc]

I didn't say that the cost of solar panels was zero. You snipped too much. Also note that the parent post said approximately that `there is no such thing as free energy', which I was disagreeing with to some degree.

Re:

[ookabooka]

Yeah, I guess the idea is to take the energy that would normally be dissipated as heat/friction and harness that. I'm still wondering if the cost of this technology makes it worth it or not. 6,500 lightbulbs may sound like a lot but if it costs millions...Also if the floor is springy it would be a chore to walk on; that could get really annoying.

Re:

[Hojima]

You can't refine energy that is dissipated as heat when it's at that level. It's mechanical energy that they use. What would be better is just a gym which uses the mechanical energy of a workout. Have bicycles that spin turbines, weight machines use the kinetic energy that power lifters exert, stair machines with similar principles etc. It wouldn't be a difficult design. With all the huge bastards at my gym, we'd be pumping out a lot of watts.

Re:There is no free lunch

[flyingsquid]

6,500 lightbulbs may sound like a lot but if it costs millions...

6500 light bulbs isn't all that much. Let's be generous and say that each bulb is a high-powered, inefficient 100-watt incandescent bulbs. 6500 bulbs x 100 watts = 650,000 watts, or .65 megawatts. To put things in perspective, a coal or nuclear plant might put out 500-1500 megawatts of power (according to various Wikipedia pages). Obviously, the power output is going to be a lot lower if they're talking about 15 watt compact fluorescent bulbs, however; that'd be about 100 kilowatts of power. That's a respectable amount of power, but you've got to ask (1) how expensive is it going to be, (2) how widely applicable is this model going to be, and (3) how reliable is this power source? Presumably foot traffic is going to decline substantially at night, and perhaps on weekends and major holidays, so the average power generation will be much lower than peak power generation.

I thought this article http://www.npr.org/templates/story/story.php?storyId=90714692 [npr.org] provided a much more practical take on the problem. Apparently, factories, mills and refineries which generate high temperature exhaust can use that exhaust to generate power. A major difficulty here is legislative, not technological; if you install the machinery to generate power from the heat produced by a steel furnace, laws designed to protect utilities mean that it's often difficult to sell it.

That being said, I don't think that recycling waste heat, or any other single technology will solve our energy problems. We need a whole suite of technologies- the ability to drill for deeper oil deposits, more cost-effective mining of tar sands and oil shales, more efficient cars, solar, wind, and more efficient houses, cars, and light bulbs- to increase our supply and reduce our demand.

Re:There is no free lunch

[evanbd]

Exactly. This article completely ignores the most interesting question -- is it cheaper or more expensive than other zero-emissions sources of energy, like solar? In some specialized applications, human power is nice. But in a supermarket or train station, power is readily available, and this should be compared on even footing in terms of $ per watt of generation capability against other options. Somehow I doubt it beats out solar power. Sure, it may be (*) cleaner than fossil fuels, but what's the point if it costs more than solar?

* Depends whether you count the marginal fossil fuel cost of food calories, which are a very expensive form of energy by the time they reach your plate. There are reasonable arguments both ways.

Re:There is no free lunch

[Escogido]

this should be compared on even footing in terms of $ per watt of generation capability

I think that if this energy source is compared on even footing with other ones, it wins hands, err, feet down.

Re:

[virgil_disgr4ce]

Unfortunately for everyone, my feet are NOT emission-free sources of energy.

Re:

[moreati]

It was too tempting, I just had to run with it.

Re:

[Andrew Kismet]

This thread is using too many puns in one place, Slashdot needs to learn to pace itself.

Re:There is no free lunch

[FinchWorld]

As well as no free energy.

There is however an amass of energy out there going to waste.

Re:There is no free lunch

[BPPG]

As well as no free energy.

Apparently somebody was paying attention in Grade 10 chemistry.

but there is easy energy

[thermian]

My son's pc is on an old Singer Sewing Table, complete with the forged Iron foot pump affair that used to run the sewing machine.

At the moment all he does is operate the flywheel while he plays (a little noisy, but better for his legs then just sitting static for ages). I want to set it up with a generator so we can use it to power something, or store the charge in a battery.

Not perhaps the most efficient means of power generation, but a teensy bit cool.

Re:

[hkmarks]

Your son is very lucky. When I was a kid, no one would let me touch our sewing table. I should have told them it was good exercise, but these were the days before NES so I doubt they would have cared.

Re:

[thetoadwarrior]

Anything decent needs investment. Sure solar panels, for instance, aren't free but as long as the sun is around they'll generate energy and the return will be greater than the initial outlay.

Re:

[v1]

why don't people "get it"? if you attach a generator of any kind to anything it will cause drag on whatever it's attached to, which is why it's able to produce energy.

If you attach a generator to your shoes, you will get power, and will get more tiring walk.

As far as walking goes, it's a pendulum-like motion that's highly efficient, and if you try to tap into that you're not going to like how tiring that walk to the grocery store gets.

Waste of resources

[jafiwam]

Humans can't power much continuously. At full tilt on an efficient machine a PRO biker can light a 100 watt bulb. The average luser working out, not worth the bother.

All the equipment, moving parts, maintained, used to capture human power won't reach the point of break even on any of this stuff. (If you pay your maintenance guy at least.)

They'd be better off CLOSING the stinking gyms and making people work out outside and not DRIVE there than capturing that power.

Green is not complicated, often, it is SIMPLE.

Re:

[kickmyassman]

Yes, hence why they're using footfalls in subway lines instead of gyms. The gym analogy was just meant as to describe the "humans produce a lot of wasted energy, why don't we harvest some?" sentiment.

Re:Waste of resources

[dougmc]

I may agree that extracting energy from humans like this isn't practical, but your figures are wrong.

A world-class bike sprinter can put out 1500-2000 watts for a short period of time, perhaps a minute or so [wikipedia.org]. Lance Armstrong can put out about 500 watts for 30 minutes or so [pezcyclingnews.com], and a somewhat lesser amount for many hours.

I'm a pretty weak pedaler, but I can put out about 100 watts for an hour or so without too much trouble.

Re:

[rale, the]

There's a significant loss in the efficiency of the conversion to electricity. You only get about 25-35% of the power you're outputting after conversion, so you'd have to put out 300-400 watts sustained to keep that 100 watt bulb going.

Re:

[tknd]

My celeron based eee 900 requires about 15 watts to idle with the screen still on. Perhaps we could put generators with pedals under everyone's cubicle desk and have them power their own computers? Not only would we be green, but we'd also solve America's obesity problem!

Re:

[elrous0]

A Chuck Norris punch can easily power Las Vegas for a full month.

Re:

[Anonymous Coward]

"not worth the bother." You mean like oil? I mean, a drop of oil can hardly power anything, thus why waste our time trying to power stuff with it?

Not green energy

[BradMajors]

Using humans to generate electricity is not a green source. Humans generate methane, a green house gas, from their fuel (food).

Re:Not green energy

[gbjbaanb]

Using humans to generate electricity is not a green source

yeah, we should ban humans and all the world's energy problems would be over.

Re:

[fahrbot-bot]

yeah, we should ban humans and all the world's energy problems would be over

Post was modded "Funny", but it's actually true. Wish there was a +1 "Ironic". I would hazard a guess that most of the World's problems wouldn't exist w/o people...

Re:

[Negatyfus]

You forget that all of these "world problems" you speak about are only problems to us "humans"...

Re:

[fahrbot-bot]

all of these "world problems" you speak about are only problems to us "humans"

Of course. People talk about "saving the planet", but whatever horror we do, the planet itself will (eventually) be fine. We, on the other hand...

Our Sun will be around for a few more billion years. Plenty of time for life on the planet to start over again.

Re:

[damn_registrars]

You forget that all of these "world problems" you speak about are only problems to us "humans"...

I think there are a variety of other species that might disagree...

• Endangered animals in rapidly deforested areas
• Yet-unknown plants in the same deforested areas
• Polar bears that aren't reaching ice floes in time
• Sea-bottom critters that are being suffocated by sea-bottom "dead zones"

Re:

[Wavebreak]

Clearly what we need is catalytic converters for people. Now to get that image out of my head.

But can certainly be recycled

[barocco]

Well the release of humans' methane, however, happens at much more predictable and organized locations, when compared to livestocks. So the collection and recycling should be easy. Now if only I have a permit and £500,000 to build a special lavatory at Victoria Underground...

Re:

[Warbothong]

Using humans to generate electricity is not a green source. Humans generate methane, a green house gas, from their fuel (food).

Well, it is green in the Soylent sense of the word........

Re:

[GodfatherofSoul]

Yes, but let me present a Modest Proposal [art-bin.com]. Additionally, we can sequester the methane with a leakproof membrane [huggiesbabynetwork.com] and put it to use in a variety of entertaining diversions [wikipedia.org]. How much more sustainable can you get than that?

Re:

[MrMacman2u]

You forgot about another source of human pollution, stupidity. They NEVER got the hang of not emitting that!

Might as well use the kinetic energy of the thousands of foot-steps we take everyday for something like generating electricity rather then wasting it all on the impact with the floor (which is cushioned by those delightful gel shoe inserts!).

190 pounds (or in the case of Americans 290lbs) striking the ground is quite a large bit of energy, I'd love to have some form of generator built into my sh

Dunno about this...

[religious freak]

How much, in terms of emissions, did this "emission free" device require when it was built? Perhaps more than 6,500 light bulbs worth of pollution?

who writes these articles?

[brunokummel]

...Obviously you'd have to get up and walk around, but, as they say, it's the thought that counts."

GREAT ! If it's the thought that counts why do I have to get up and walk around??..I could only imagine that I'm walking around and watch those batteries juice up....

Emission free?

[BobNET]

I'm pretty sure my feet are producing harmful emissions right now...

Re:

[BobNET]

Especially if your name is Al Bundy [marriedwithchildren.com].

The episode where Al's dirty socks power an alien attack force was on my mind when I wrote my comment...

Hmm, it's getting dark in here.

[Have Blue]

Five minute break, everyone. Do a few laps around the office.

Cool toy, but...

[RyanFenton]

This sounds as practical as trying to harness the 'incredible power' of our stomach acid for energy generation. I'm sure we could power a lot of lightbulbs in a lot of ways - but I think there are better options than relying on extracted energy from human movement. It's like relying on whale and pig fat as a major power source - it just doesn't scale past a small market segment.

What we want is to use something more scalable, like algae-based oils [wikipedia.org], using arid and other unfarmable land, and not using fresh water sources for production. That, plus increases in solar power efficiency are much more direct ways of gathering usable energy, which could scale far beyond our current needs in a sustainable way. That way, we raise the standard of living of people by increasing energy production, rather than make them stick battery chargers on their feet.

Ultimately, food and fresh water will be bigger concerns going forward - and I don't think we'll be able to grow sustainable crops in our shoes with any toys either.

Ryan Fenton

Re:Cool toy, but...

[rocketPack]

Exactly. Why would we want to rely on an unpredictable, complicated solution to generate a small amount of electricity when we could be harnessing lots of other sources which are much more reliable, scalable, simple, and cheap!

What about using EM induction to slow down trains? How much electricity could a freight train generate if it stopped using a "third rail" and some magnets beginning a few miles out of town (when it'll already begin slowing down). The savings in mech braking wear and tear, the usefulness of the quantity of electricity generated, the predictability, reliability, simplicity, and cost of such a system make this idea seem so much better than trying to harness the power of "walking."

But we're not into "useful tech", we want something "clever" sounding and "outside of the box" - even if it's really useless and a waste of resources that could equivocally produce a superior, albeit "boring" and "obvious" solution.

This green revolution made so much more sense when it didn't have the all the hype. Bring back the old timers!

Re:

[RyanFenton]

This green revolution made so much more sense when it didn't have the all the hype. Bring back the old timers!

Well, that depends on how you define the Green Revolution [wikipedia.org]. I prefer to define it in terms of agriculture and human production standards. In terms of the work of Norman Borlaug [wikipedia.org] and other scientists' contribution, rather than as a way to dismiss folks as leftist, which these folks in particular are not. That work has likely saved the lives of more people than almost any other act in human history.

T

Re:

[Zak3056]

What about using EM induction to slow down trains? How much electricity could a freight train generate if it stopped using a "third rail" and some magnets beginning a few miles out of town (when it'll already begin slowing down). The savings in mech braking wear and tear, the usefulness of the quantity of electricity generated, the predictability, reliability, simplicity, and cost of such a system make this idea seem so much better than trying to harness the power of "walking."

What you're suggesting has bee

Re:

[mdielmann]

That way, we raise the standard of living of people by increasing energy production, rather than make them stick battery chargers on their feet.

In theory, I agree with you, but given the current situation people's standard of living would be increased if they spent a little more of the energy they already consume.

Re:

[zippthorne]

Nuclear energy IS clean energy. You're pouring water over hot metal to generate steam, and you do it in a closed loop. It doesn't get much cleaner than that.

My feet are always green energy

[LM741N]

Thats because I made a conscious choice to live in the city. I can walk to almost anywhere I need to, and on those rare occasions that I can't, there is always the bus. Plus I get the additional benefit of lowered chance of cardiovascular disease and others so I'm not going to weigh down the health system like the lazy people out in the suburbs. They drive everywhere with their gigantic SUV's, polluting the environment and turning into big lumps of fat.

Re:

[GodfatherofSoul]

How's that clean city air and population density-induced stress treating the unadulterated temple you call a body?

Maybe the tap-dancing grifter

[antifoidulus]

can now get a job working to keep the train stations power bill down.

Everybody Dance Now...

[fahrbot-bot]

powering iPods by plugging them into batteries placed in the owners' heels, ... Obviously you'd have to get up and walk around.

Or dance, if you follow the iPod commercials...

The idea is not as bad as it seems

[ZarathustraDK]

Getting all nerded up and talking about "there is no free energy" only covers it partly, specificly the bad part.

In 'reality' though there are certain bonusses to a soft walking surface.

1. You get more traction and reduce slipping of feet (which is a problem on hard surfaces with grains of sand on it).

2. Damage from falling is reduced.

3. A soft surface is easier on the joints, which is important for everyone, though especially elderly and disabled people.

Try finding one of those new fancy playgrounds with a semi-soft rubbery-like surface and walk on it. Much more comfortable to walk on compared to concrete.

Green?

[Tablizer]

If I don't wash them, they do turn green. Does that count?

Bwuh?

[Phanatic1a]

.. The plans for heel-strike generation follow successful trials last year at a bridge in the Midlands where generators converted energy from trains passing above into electricity powering a flood detector.'

That couldn't possibly be more efficient than just plugging the flood detector into the same source that powers the trains.

It is much more efficient

[ctid]

Because you have to get the oil which powers the source from your sworn enemies.

What's with all the negative waves?

[Charcharodon]

Someone could come up with a power source that is practically free in every sense, and the majority of the people on /. would tear it down.

If we could build a device to pick up all the negative waves around here, the amount of energy collected would cause the Sun to snuff out a septillionth of a second later.

Its a cool idea, even if its not 100% practical. Throwing around the standard "there's no free lunch" response doesn't prove your smart, it just proves you're an asshole.

Re:

[LM741N]

Hey, don't mod that one down, I thought it was hilarious- and true.

How about harness doors?

[British]

Take a door in a public place. There's a hydraulic mechanism to make sure it doesn't slam shut. There's a bit of a resistance when you open a door. Think of how many times doors in public places open & close on a given day. Sure, it may not be much per 1 door open/shut, but imagine a shopping mall or office with hundreds of doors.

Take the hydraulic damper and turn it into a generator. Chain together all the doors and have it provide power peak power hours(when the public will be using them). Make them compatible(ie mount-wise) with existing dampers & retrofit them everywhere.

Slap a generator on those revolving doors too. Imagine the power it could make in a busy downtown area.

Dang, I should patent this before.........

Re:How about harness doors?

[isj]

Already done in the comic Gaston [wikipedia.org], where he invented such a device which could press the juice from 4 oranges, grind 30g coffee and stamp 5 letters. His coworkers were not pleased.

Ever heard of thermodynamic?

[Anonymous Coward]

Given than a human muscular efficiency is considerably less than most combustion-based engines, and considering the energetic cost of producing then delivering the food in the first place is itself steep, I expect the net energy gain to be gruesomely negative. Most corn-based biofuel plants in the US fail to "get even" right now: this is an even worse bet.

Even better...

[NerveGas]

As that will make it harder for people to walk, and they will have to expend more energy... that means greater sales in the food court. Woohoo!

What we really need

[Orig_Club_Soda]

is all these exercise machines America uses is to plug in to the wall and transfer the energy we expend at the gym and home to be put to use rather than wasted in heat and friction.

Re:

[r_jensen11]

is all these exercise machines America uses is to plug in to the wall and transfer the energy we expend at the gym and home to be put to use rather than wasted in heat and friction.

What we need is for all of these exercise machines Americans have to actually be used. You know, exercise machines such as road bikes and the like. The way I see it, so much energy being consumed in America is wasted because it's duplicating work. Why the hell people drive 10 miles each way to the gym to use exercise bikes for an hour or two is beyond me.

There was a Ziggy cartoon that addressed this issue; however, instead of using exercise bikes, I believe it involved a treadmill....

What about Zero Point Energy?

[LM741N]

cold fusion, and magical Tesla power transmission. Ok, I'm just kidding, but I couldn't resist.

But who owns it?

[Thyamine]

It would be nice and all, but if all these people are helping generate the power, how is it being used/sold/distributed? Do they get a discount of tickets/merchandise? Is it required that the power gets freely distributed in some manner? If they are making money off of it (as they no doubt will want to, even if it's only to conserve their own electric bills), I want to be compensated in some fashion.

Re:

[Vegeta99]

How do you think you'll be compensated? You'll be compensated by having a store that's lit and still cheap, versus one that's lit and now twice as expensive.

Batteries WHERE?

[Alsee]

for example powering iPods by plugging them into batteries placed in the owners' heels

I have a better idea. How about we put the batteries in the shoes instead?
I'd really rather not have a Sony Battery surgically implanted in my foot.
Results 1 - 10 of about 289 from slashdot.org for battery fire Sony. (0.08 seconds) [google.com]

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Old news

[vrjim]

This was brought up in the media last year from the folks at MIT: http://archive.uwire.com/2007/09/11/mit-students-take-step-toward-cleaner-greener-urban-energy/ [uwire.com] In fact, I could have sworn I saw the story run here on Slashdot. Can't we just reference the arguments from then so we don't have to rehash them?

HOW do you...

[solitas]

...get everybody to walk in lockstep to synchronize the pumping action? With random footfalls you'd have to have a LOT of smallish pumping cells with a lot of valves to keep it all flowing properly.

TFA: "It works by using the pressure of feet on the floor to compress pads underneath, driving fluid through mini-turbines that then generate electricity, which is stored in a battery."

Additional Benefits

[dave87656]

It seems that stepping on a tile with pads which push fluid through turbines would have kind of a gel effect or feeling to the people walking on them. This could reduce the impact on the joints and perhaps the fatigue of walking around.

The green broken window fallacy

[4D6963]

Here's something I've been wondering ever since I found out my body could generate peaks of 400 Watts at the gym. Is human energy really green?

My analogy to the broken window fallacy is based on the fact that this fallacy relies on what we see (the store owner buying services from the glazier) versus what we don't see (the store owner not investing that money for better purposes). Note that the logic also holds for alternative energies such as electric cars (which electricity comes from coal power) or ethanol which has to be processed/transported in a polluting way. So how green is human power? Considered that what powers us is food, we have to look at how much energy is involved in the making (making that cow live, eat and die involves making its food, transportation, etc..), the transformation and the transportation (a lot of the food you eat has travelled thousands of miles). Also it's important to note that just because it's necessary for us to eat food anyways, it doesn't make our energy free. You'll need more food if you produce 100 Watts for 30 minutes (say, if you're jogging) than if you just lay there.

Unfortunately I'm not qualified to estimate how polluting human power actually is, but I'm sure it's far less greener and more expensive than most people would assume. I think it's just yet another of these "feel good" measures that are actually not that good at all. When will we realise that there's no problem that can't be fixed by throwing a few trillion dollars into nuclear power and r&d?

Re:success to-date sounds limited

[mikael]

I would think that piezo-electric mats that absorb sound would create more energy while at the same time reducing the amount of noise would be more practical than collecting potential energy from passing trains.

Re:

[evanbd]

You would be wrong. There's just not much energy in sound. A 100W sound system is quite loud -- and the speakers are only a few percent efficient. A few watts of sound is *very* loud; the energy available from covering the walls of a normal room is a couple watts at best, before you count inefficiencies.

Re:

[Yetihehe]

.well that GPS is great for getting me out on my bicycle, and off into unexplored territories. I just love it. Except when it dies because it sucks too much juice, which is most of the time. (so I have learned to carry spares)

I love it too. But I just have Dell X5 palmtop, and 3400mAh battery, it works approximately 6-7 hours this way.
*guitar riff* *guitar riff* *(Ding! Turn left in 300m)*

Re:

[Yetihehe]

It would be actually cool if some dynamo with charging capabilities existed. Just like cross between bicycle dynamo and sidewinder phone charger [americansurvivalgear.com].

What you're forgetting is ...

[ctid]

.. that the person would be there anyway. You have to think about this idea as recovering wasted energy, rather than generating new energy because all those people are walking about anyway.

Re:

[iMaple]

'34,000 travellers passing through every hour could power 6,500 lightbulbs' - for how long? Probably for one minute, although they seem to be trying to imply a day.

Well, an hour is what they are implying.