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Stephen Kamizuru (Blog) - December 15, 2008 10:04 AM

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42 comment(s) - last by William Gaatje.. on Dec 21 at 5:01 AM

(Source: http://www.letsjapan.markmode.com/)

Commuter generated electricity used to light up Christmas lights

According to a LetsJapan article, special panels have been installed outside Shibuya station in Tokyo that generate electricity when commuters walk over them. The panels were installed by the Shibuya ward government and are set up near the Hachiko dog statue outside Shibuya station.

As Shibuya station is one of the busiest stations in Tokyo it is an appropriate location for the panels. Living in Asia you witness armies of people marching through busy train stations every day. Any innovation that can harness this energy is a positive development.

The panels are 90 square centimeters and 4 of them were installed beside each other. The panels are 2.5 centimeter thick piezoelectric mats and a person weighing 60kg can generate 0.5W by stepping on the panel twice.

The electricity generated is used to run an electronic light emitting display board in the Shibuya plaza which continuously updates the total amount of electricity generated. A small Christmas lights display is also powered by the piezoelectric panels. The floor panel can withstand light rain but is not completely waterproof and are scheduled to remain until December 25.

The panels were developed by a company called Soundpower Corp. and can be rented for a fee according to their website. The panels come in various sizes and versions and can be used for research and educational purposes.

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60kg x 2 = 0.5W ?????

By Schrag4 on 12/15/2008 12:14:25 PM , Rating: 4

quote:
a person weighing 60kg can generate 0.5W by stepping on the panel twice

0.5W isn't a unit of measure that makes sense here. And to say stepping on it twice generates 0.5W confirms that it doesn't make sense. I can guess what it means, but that's just speculation...

RE: 60kg x 2 = 0.5W ?????

By mmntech on 12/15/08, Rating: 0

RE: 60kg x 2 = 0.5W ?????

By masher2

(blog) on 12/15/2008 1:05:26 PM , Rating: 4

The problem isn't the lack of a voltage specification, it's the old energy-power confusion problem displayed by most media stories on the issue. One is a rate, the other a discrete quantity.

Two steps on a mat will generate a specific amount of energy (joules, watt-seconds, kW-h, etc.), whereas watts are a rate of energy generation.

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RE: 60kg x 2 = 0.5W ?????

By mars777 on 12/15/2008 10:31:27 PM , Rating: 2

There are more panels there and more people stepping on them simultaneously. I guess you can count the steps per day and transform that into kilowatts/hours (of course there will be variations during the day but not so much for a station that sees millions of people per day).

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RE: 60kg x 2 = 0.5W ?????

By Schrag4 on 12/15/2008 11:52:12 PM , Rating: 2

Ok, not trying to be a jerk, but you're just not getting it. 0.5 W, but for how long? A nanosecond? If that's true, 100 BILLION (with a B) people stepping on this TWICE would only produce 100 WattSeconds, enought to power a 100W lightbulb for 1 second.

Obviously it will be longer than a nanosecond, but the article doesn't say, so it's PURE speculation. It might be great, but it doesn't sound like it is...

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RE: 60kg x 2 = 0.5W ?????

By matt0401 on 12/16/2008 12:17:15 AM , Rating: 2

It is indeed very badly stated. I think what they mean is that a person will generate 0.5W continuously as they walk over the panel (usually using two steps). If this is the case, it reaffirms the previous posters' claims that this is a negligible amount of power. 0.5W would be generated continuously as a steady stream of people walked over these in an entrance or exit to a subway station. If this were to last all day long it would still only be 12 Wh generated per day. That would be a very long return on investment even if these things became cheap when mass-produced. They would also have to install them almost everywhere just to produce a noticeable contribution to the power grid.

It's definitely a neat proof of concept though. And that's obviously what the intention was here.

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RE: 60kg x 2 = 0.5W ?????

By royalcrown on 12/16/2008 5:49:49 AM , Rating: 3

Yes, but you're all missing the point that the first few iterations of any technology or invention are usually inefficient and sucky. Look at the battery invented by Volta, I mean beck in the day, you guys woulda said how bad it was and it's not very useful because it's not powering your laptop...blah blah.

Look at the first LCD monitors, they sucked too, but now they're decent because ppl kept refining them.

The first light bulbs...guess what, not bright at all. Point is that this may have a lot of room for improvement.

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RE: 60kg x 2 = 0.5W ?????

By Hoser McMoose on 12/16/2008 6:32:30 AM , Rating: 2

Even if this panel improves by several orders of magnitude it will still be a toy.

If matt0401 guess on the meaning of the numbers is correct (and it seems reasonable), we're looking at a best-case scenario of it generating 12Wh per day, or 4.4kWh per year. Even in Japan, with electricity costing twice as much as in North America, we're still talking about less than $1 per year.

Add in that you aren't going to get a stead-stream of people walking on your panel 24/7 and even if this panel improves by 1000 times it's still won't be anything other than a toy.

Interesting toy, but a toy none the less.

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RE: 60kg x 2 = 0.5W ?????

By royalcrown on 12/16/2008 7:20:26 AM , Rating: 2

Sure I can get a steady stream of ppl walking on it, that's easy:

Just glue a wallet on it, or a fake mp3 player.

Besides, it should be refined and maybe it will find a use someday such as self powering Ipod Nano 9 thumb wheel or something...

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RE: 60kg x 2 = 0.5W ?????

By Lugaidster on 12/18/2008 9:29:54 AM , Rating: 2

You guys are simply not thinking right. Lets put it this way, you are right that it only generates 12Wh in a day, but that is only one person walks all day in it. If one person in one panel generates 0.5W then two persons in two panels would generate 1W. Now, if you have 1000 panels and 1000 people walking all the time over them you get 500W or 12KWh in a day.

It is still inefficient and not that much energy is produced but, but it's not as much as you think it is. If it were to improve a 1000 times like you said, it would generate 500KW or 12MWh in a day. Now that is a lot for a metro station (not enough to power the train it self, but the rest of the station). Granted, it may not be possible to improve that much.

Ofcourse, all of the above is only possible if a continous stream of people walked over 1000 panels and that you still need to lay 1000 of these panels somewhere.

Not quite ready for primetime but an interesting toy nonetheless.

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RE: 60kg x 2 = 0.5W ?????

By Lugaidster on 12/18/2008 9:32:51 AM , Rating: 2

Sorry, meant to say not as little energy, or not as inefficient as you might think.

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RE: 60kg x 2 = 0.5W ?????

By masher2

(blog) on 12/18/2008 11:21:34 AM , Rating: 2

> "If it were to improve a 1000 times like you said, it would generate 500KW or 12MWh in a day"

It doesn't work that way. You can't improve efficiency past 100%, and you can't create energy out of nothing. A person walking on level ground isn't expending much energy (~1/10 hp =~75w or so). Even if you captured it all, you wouldn't get anywhere near 12MWh/day from 1000 people (less than 1/6, to be precise).

But that's only part of the picture. Nearly all that energy is being used to actually *move* your body. You can't capture more than a small fraction without increasing the effort required to walk. When you step on a piezo crystal, you're turning compression into electricity. The compression in this case is a minute fraction of an inch, which means you don't notice it while walking...but it also means you can't capture more than a tiny fraction of the total.

So what if the system actually did capture more? Well that increases your effort level, meaning walking is harder. In effect, you'd be turning expensive food energy (which has to be fertilized, grown, fed, whatever) into cheap electrical energy. Even without the massive conversion losses and inefficiencies, that's still a bad idea.

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RE: 60kg x 2 = 0.5W ?????

By Lugaidster on 12/18/2008 1:57:52 PM , Rating: 2

I know you can't get past 100% in efficiency I was burrowing a statement from someone else (although you are probably right, most likely 1000 people can't generate 12MWh in a day), but still that is not a discrete number, for all I knew (before your post) the energy generation process could be only 0.05% efficient (so 1000 times more would be feasible).

Now, if you are right about the compresion part, walking doesn't have anything to do with generating energy (unless it only generates energy while compression varies) in this mat, just standing there would generate the compression needed. How much energy that is, I don't know, so I can't say. And the energy wouldn't be coming from you (not all of it at least), but from the gravitation force.

Anyway, my point was that the system wasn't generating 12Wh a day from all the people that passed there. 12Wh is just the figure for one mat and one person. Increasing both would increase the output directly. So, 1000 people would generate 12KWh of energy a day. Although that would require 1000 people walking over the mats all day, which may not be possible.

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RE: 60kg x 2 = 0.5W ?????

By masher2

(blog) on 12/18/2008 4:19:46 PM , Rating: 2

> "in this mat, just standing there would generate the compression needed"

I apologize for not being more precise. It's not compression per se that creates energy, its the change in compression.

Compress an piezo crystal and you generate an electrostatic field. Drain off that charge and you can do work with it..but you get no more until you recompress the crystal. It's not a continual output.

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RE: 60kg x 2 = 0.5W ?????

By Schrag4 on 12/16/2008 10:09:27 AM , Rating: 2

quote:
Look at the first LCD monitors, they sucked too, but now they're decent because ppl kept refining them.

quote:
The first light bulbs...guess what, not bright at all

Ok, yeah, the first versions of those sucked, but they did their job.

Now what's the 'job' of these panels? To capture energy and turn it into electricity, thereby reducing the amount of fossil fuels that we have to burn in order to live our lives, right? Well guess what. These, in their current form, take WAY MORE electricity to produce than they will ever save. So they aren't doing their 'job', unlike the first light bulbs and the first LCD monitors.

I have no problem with researchers trying to refine them in the lab, on a small scale. I think that's great. But to produce these in their current form is actually (if you buy into it) murder to the environment. Sounds like a perfect thing for the government to step in and provide subsidies for. *rolls eyes*

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RE: 60kg x 2 = 0.5W ?????

By royalcrown on 12/16/2008 10:42:15 AM , Rating: 2

I never said make em like pizzas and I agree on the subsidizing. And you don't think all the prototype lcd's and light bulbs, and automobiles and whatnot took more energy than they should have ?

The first cars were toys that served no practical purpose, along with a lot of things such as tv, my only point being how will we know that this is useful or not for some un thought of application. Same thing with C60 a.k.a "buckminsterfullerene", the predecessor to carbon nanotubes.

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RE: 60kg x 2 = 0.5W ?????

By William Gaatjes on 12/21/2008 5:01:42 AM , Rating: 2

When i think of a typical lighter with piëzo ignition, it produces enough energy to run some leds in combination with some basic electronic components for a few minutes. I know this because i used to have such a device just to know how it works and it had no batteries in it. Afcourse the spark generated by the lighter is done with a mechanical acceleration of some weight hitting the piëzo crystal. I think this is usuable in shoppingstreets, public transport stations airports. Afcourse this is not going to solve the energy problem but it sure will make a difference when used for efficiënt led background lighting, led lighting for billboards, led based "neon" signs etcetera.

When improved, we may make our roads of it. A special tile that creates minute clicks when a car drives over it. the clicks are transfered to (random generated number)1000 of piëzo crystals. We salvage the sparks and store the average energy. Make these tiles exchangeable and replacable. This creats the option to refresh roads. This also allowes immidiately that we can improve our roads for computer based driving where the vehicles take control of driving and negotitation. We sit in our vehicles but we can read a newspaper, do some internetting while driving since we don't have to pay attention.

We can harvest energy from everywhere and everything if we want too. Combine all that and we don't have to worry anymore... Future based electricity will come from many different sources. This also creates disciplines which in turn means many specialized companies creating jobs. And these jobs will always exist since electrical energy demand will be rising and energy will always be a necessity.

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RE: 60kg x 2 = 0.5W ?????

By spread on 12/16/2008 6:02:57 PM , Rating: 2

These can probably power a console and a DDR pad.

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RE: 60kg x 2 = 0.5W ?????

By theboomboomcars on 12/18/2008 1:19:36 PM , Rating: 2

The bottom photo shows that there has been 211.53667 kWS, though it doesn't show how many people have stepped on it.

With a little conversion it looks like that is about about .06 kWh.

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Are you sure?

By masher2

(blog) on 12/15/2008 12:33:26 PM , Rating: 2

quote:
Any innovation that can harness this energy is a positive development.

Why? A vastly expensive device (meaning it required massive amounts of labor and/or resources to build, all of which consume energy) which generates negligible amounts of electricity is not a net gain.

I have no idea how much these mats actually cost -- but the fact they're apparently only being rented, rather than sold outright, is a fair bit of evidence they're far from viable at present.

RE: Are you sure?

By monomer on 12/15/2008 5:03:54 PM , Rating: 3

What are you talking about? These things are amazing. They produce enough energy to, uhhh... display how much energy they produce.

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RE: Are you sure?

By Tsuwamono on 12/15/2008 7:48:03 PM , Rating: 2

if you think about it though... imagine all major subway stations or air ports had these installed. They could probably put enough energy to at least offset the amount of energy the building takes from the grid. And when you remember that we are 6.5 billion people and growing we might as well take every bit of electricity we can generate. Granted this needs to be refined so it takes less energy to build but once thats done it may actually make sense.

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RE: Are you sure?

By masher2

(blog) on 12/15/2008 8:09:02 PM , Rating: 2

> "They could probably put enough energy to at least offset the amount of energy the building takes from the grid."

If that building needs to be heated or cooled-- not even close.

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RE: Are you sure?

By jadeskye on 12/15/2008 8:18:05 PM , Rating: 2

I don't think it should be THAT condemned =)

Don't get me wrong it's horribly inefficient, but it's a new way of thinking if nothing else :p

maybe one day if we could wire all the sidewalks of new york or London, this it could have a positive effect on energy.

particularly if you can get them to be reliable and last many years.

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RE: Are you sure?

By TheSpaniard on 12/17/2008 8:25:44 AM , Rating: 2

I dont think its inefficient, I think there is not much energy to be used here

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RE: Are you sure?

By mars777 on 12/15/2008 10:25:35 PM , Rating: 1

50 thousand people stepping on the panel per day is a huge underestimate since more than a million people passes on that station per day.

Anyway for this example thats 25000 watts per day.
More than a kilowatt/hour.

In a few days they should be fine and in positive gain i assume.

Plus this development may have some impact on the study of future use of piezoelectric systems and i cannot see why should you bash so hard for something clever.

Masher is a Basher :D

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RE: Are you sure?

By Hoser McMoose on 12/16/2008 6:42:13 AM , Rating: 4

quote:
Anyway for this example thats 25000 watts per day.

Uhh, do you realize that "25000 watts per day" is not a valid measure of anything? The units here are so horribly mixed up that it doesn't make any sense at all. What you're saying is about the same as saying that a mountain is a 100 miles per hour tall.

The article doesn't actually properly state how much energy or power are generated, but the best-guess is that runs at a peak power of 0.5W if you have a constant flow of 60kg people walking on it. That works out to a maximum amount of energy generated of 12Wh through a day, or approximately 4.4kWh per year. In the U.S. that is about $0.40 to $0.50 of electricity generated per year.

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RE: Are you sure?

By royalcrown on 12/16/2008 7:23:32 AM , Rating: 2

True, but it may have a valid application in the future, so why not experiment and see about getting it more efficient in the mean time

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RE: Are you sure?

By mars777 on 12/16/2008 5:06:55 PM , Rating: 2

You are true, it would be 25000 wattdoublesteps per day.
Having a double step last for two seconds...

Can you tell me if this calculation is correct?

25000 / (doublesteps in one hour) per day = 25000 / 1800 = 13.8 Wh ?

This assuming the energy lasts as long as the flow of steps is constant.

If true at least every panel could have a Christmas light lightened :D

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RE: Are you sure?

By PlasmaBomb on 12/17/2008 3:48:37 PM , Rating: 2

There are four panels so what you are saying is that they could run four 1W LED Christmas lights for almost 14 hours a day off the energy generated by people walking over the mats 24/7...

Excuse us while we don't jump for joy at a multi-thousand dollar mat saving us 0.0138kWh (0.1 cent @ 10 cents per kWh) per day...

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Imagine...

By eek2121 on 12/16/2008 2:41:47 PM , Rating: 2

I think everyone here is missing the point. Panels like this may produce a miniscule amount of power, but lots of them added up, along with other forms of electricity generation, could provide considerable energy savings. Imagine if these were waterproofed and designed to look like tiles/wood paneling, they could be installed in each room in the home and any walking/movement would help keep a battery charged. Combined with solar panels this would help power your house.

RE: Imagine...

By FITCamaro on 12/16/2008 2:52:30 PM , Rating: 3

Sorry kids. No hot water today. You didn't play DDR enough last night.

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RE: Imagine...

By rubyxc7 on 12/18/2008 10:56:06 AM , Rating: 2

If they turned it into a blanket or the top of a matress... Imagine the collective power output of the world doing the dirty... Wouldn't be useful as power output but it would be an interesting statistic...

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RE: Imagine...

By masher2

(blog) on 12/16/2008 3:11:53 PM , Rating: 3

> "Combined with solar panels this would help power your house..."

Let's assume the prior calculations are correct, and that one panel, while being walked on, generates 0.5W. Now let's assume a family of four in a home, with a very optimistic duty cycle of 50% (you spend 12 hours a day walking in your home). That works out to a net power output of 2 watts -- about half of what one single night light generates.

Not a light bulb. A 4watt night light.

Contrasted against the power required to manufacture, install, and maintain these panels, reaching breakeven seems quite unlikely.

The industrial age was born when we replaced the power of human muscle with more powerful, plentiful sources. I can't help but look at 'innovations' like this as an enormous step backwards.

Now in some fringe areas I can see potential applications. If the panels are light enough and have innate structural strength, then areas like a space station or remote camping facilities might benefit from this. But as a solution -- even a partial solution -- to powering society? Not in a thousand years, not in ten thousand.

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RE: Imagine...

By FITCamaro on 12/16/2008 3:17:22 PM , Rating: 2

Astronauts don't walk in the space station...

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RE: Imagine...

By masher2

(blog) on 12/16/2008 3:35:37 PM , Rating: 2

Not in this one, they don't...but in future ones, they will. A little spin to impart artificial gravity, and you're in business.

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RE: Imagine...

By FITCamaro on 12/17/2008 9:00:28 AM , Rating: 2

It's taken us nearly 20 years to build the piece of crap we've got.

I seriously doubt that there will be enough interest and support worldwide to build another one any time soon. There certainly isn't enough in America.

Only way its going to happen is if a company does it.

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RE: Imagine...

By Korvon on 12/17/2008 4:41:35 PM , Rating: 2

I wonder if this could be placed at the bottom of a shoe to a small battery pack. Go for a jog and power your MP3 player or Cell. The wattage on those would be small enough it might be viable. Just a thought.

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How?

By Heir on 12/17/2008 12:55:59 PM , Rating: 2

So how exactly does it generate electricity?

RE: How?

By masher2

(blog) on 12/17/2008 1:42:28 PM , Rating: 2

The piezoelectric effect-- it translates pressure on a crystal into a (tiny) amount of electricity.

Some cigarette lighters have long used a piezo crystal for the spark used to ignite the gas ... it's a more permanent solution than the misch-metal "flint" wheels the ultra-cheap lighters use.

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