Piezoelectrics installed in Tokyo railway station floors generate power, wastes it

The East Japan Railway Company has been running tests on a "power-generating floor" since the beginning of January 2007, but they've just installed the system for public testing in several areas of the Tokyo station. Using piezoelectrics similar to that we've seen before in a UK discotheque, the Japanese company says the power-generating capacity of the flooring has increased ten-fold over its initial results, and they now expect to generate 1,400kW/sec per day. With that, they plan to power the display pictured above, which shows the power generatd by the floor. Sound a little redundant? Fear not: they plan on using the juice to operate automatic ticket gates in the future.

[Via Inhabitat]

[go seki @ Dec 11th 2008 4:01PM]

Piezoelectric subway cars next ??

[a @ Dec 11th 2008 4:41PM]

How about a series of strips along bridges / other highly traveled roads... Tens of thousands of cars per day, along with greatly increased weight and therefor potential energy.

[Sea Urchin @ Dec 11th 2008 4:48PM]

@ a, you got that right. Shame here in USA we are too busy spending money of Auto bailouts, war and such.

[Funke, Tobias Dr. @ Dec 11th 2008 5:41PM]

The increased resistance on the vehicle tyres would negate the energy recouped. You can't get energy from nothing. And you can't transfer it without loss. You'd be bleeding away (adding more resistance) kinetic energy from the vehicle in order to power a less efficient system.

This whole concept is like a jetpack; sure it works, but for practical applications, it is an order of magnitude below the necessary capabilities.

[Grey Acumen @ Dec 11th 2008 6:05PM]

I'd still like to see this done on more things, even if it's just for people. I'm just imagining what you could do if every sidewalk in new york had something like this.

[Kakkoii @ Dec 11th 2008 6:21PM]

@Funke:

What increased resistance? It would be almost like normal road you drive over. The amount of movement a piezoelectric would need isn't much. It's harnessing gravity as the car rolls over, it's not harnessing the cars power. Just the power exerted from gravity pulling the car down on the piezoelectric pad.

The energy wasted in the car is used to move the car along the road, which it already does, piezoelectric road or not. The car doesn't use more energy to move over one solid surface than another. There's just no system in place to capture the gravitational force, force exerted by the spinning tires and momentum of the car exerted by cars on the pavement.

[Funke, Tobias Dr. @ Dec 11th 2008 6:27PM]

Have you ever tried running or driving on sand? Even wet roads cause a decrease in MPG because of a change in rolling resistance.

http://en.wikipedia.org/wiki/Rolling_resistance

[1234321 @ Dec 11th 2008 7:23PM]

Funke, what do you think about the idea of windmills along the middle of a two way freeway, it would rotate along the x,z plane and turn with the wind from both directions

[Funke, Tobias Dr. @ Dec 11th 2008 8:06PM]

That sounds like it would work in theory; again though, at such a small scale, the amount of energy you would recoup wouldn't be worth the time/installation/maintenence costs. If you had the resources to deploy a system like this, you'd be better off building something with a higher level of efficiency. It's all about scale.

[Kakkoii @ Dec 12th 2008 12:20AM]

@Funke: Ok if where going to go down that route, then that would make piezoelectric roads even better for MPG. As they are hard and are smoother than asphalt..

[Funke, Tobias Dr. @ Dec 12th 2008 2:25AM]

My point is that if you are going to scale it to the point where the energy you are recouping is worth anything, the resistance added to the vehicle would cause a greater loss of efficiency to the vehicle than the energy you are getting out of the road. It just doesn't balance. Just scale it up in your mind to picture why it really isn't practical.

For instance, imagine a sidewalk made of this material that sinks so little when you step on it, it feels like concrete to your foot. This would generate very little energy per step of course. Now imagine one where every step you take, the sidewalk sinks in an inch. This would generate many times the energy of the first, but it would be much more taxing for you to walk on. In the first example, the energy output of the system would not be worth the time and expense of harnessing it. In the second example, the energy output would be much greater, and maybe marginally worthy of the expense of capturing it, however, it would be much more taxing to someone walking on it. Now imagine what I've described, but substitute vehicles and roads.

http://upload.wikimedia.org/wikipedia/commons/c/c4/SchemaPiezo.gif (best illustration of the concept)
http://en.wikipedia.org/wiki/Piezoelectric#History (the above image in context)

[Wwhat @ Dec 12th 2008 8:50AM]

Amusing, funke is an ignorant fool but by calling himself dr while spouting nonsense he gets high ranked, whereas the smart people showing how foolish he is are remaining neutral ranked.
I noticed that before on engadget, people vote positively on what they think might be 'smart talk' and not on judging if it actually is smart, it just has to sound technical or as if it's displaying expertise, which works often but obviously fails plenty too.

[Funke, Tobias Dr. @ Dec 12th 2008 5:43PM]

So Wwhat, what do you disagree with exactly? I'd rather hear your criticism of where I'm wrong, than be insulted; that doesn't solve anything. I hope you'll oblige me in that.

[I LOVE THE CAPS LOCK KEY @ Dec 13th 2008 1:25AM]

Dr. Tobias.

You are semi-correct.

Why not put piezoselecronics under the steel track (think suspension) and let the weight of the train push and it's vibration down (compress) on the device?

[Funke, Tobias Dr. @ Dec 13th 2008 12:21PM]

CAPS LOCK, I think that sounds to be more efficient, but again though, the tracks aren't constantly in use, and even in the most used track length in the world, the energy that you would get back, for the amount of time and resources you spend installing a system like this would not be worth your investment. You would simply be better off spending the time and money installing a solar panel or windmill.

When materials technology gets to the point where this is cheap and easy to deploy, other alternatives that provide more energy will surely have leapt ahead several generations, making this akin to using rainwater runoff to run a small turbine for frivolity.

[I LOVE THE CAPS LOCK KEY @ Dec 13th 2008 9:45PM]

No one ever said there would be a high energy return on investment. Even I don't think it's worth while to do this, but every little gain is still a gain.

He's not a doc, he just portrays one on TV.
http://www.google.com/search?hl=en&q=Dr.+Tobias+Funke

[Jane Edmunds-Reeb @ Dec 11th 2008 4:02PM]

This is an excellent experiment. Kudos.

[Stuhe @ Dec 11th 2008 4:03PM]

Watts are already joules per second. Watts per second is an acceleration.

[Adam @ Dec 11th 2008 4:07PM]

It's not watts per second, it's watt-seconds. 1,400 kW-Sec means it can deliver 1400 kW for one second; or, 140 kW for ten seconds, etc. Incidentally, this means the floor generates 388 watt-hours per day.

[potato @ Dec 11th 2008 4:36PM]

388 Wh a day?! That's ridiculous - that powers 2-3 laptops for a single HOUR. Why are people spending a huge amount of money installing these so they can save $0.03 a day? How long would it take to recoup the energy cost, not to mention monetary cost, of producing these floors?

Environmentalism goes way too far sometimes.

[therpham @ Dec 11th 2008 4:40PM]

@Adam: I believe Stuhe was pointing out the typo: the slash after kW implies that the measurement is kW per second per day.

[HunterXI @ Dec 11th 2008 4:47PM]

Stuhe's still right, even if he misunderstood the units. This article should have provided the amount of energy as an amount of energy (joules), not as power-time. It's like saying, "I just walked 3 mph-hours", as opposed to, "I just walked 3 miles".

[Anthony @ Dec 11th 2008 5:15PM]

The article is very wrong, as it says W/sec, which means Watts per second, i.e. Joules per second squared. So W/sec/day is Js^-3 :D

1400000 / 24 / 60 = 16W. Not so impressive.

[Temple @ Dec 11th 2008 5:45PM]

it currently uses only that small black patch, clearly its technical experiment. You have to start somewhere- the real question is how much it'll cost to have these all over the subway once the technology becomes developed over time. If they can get it cheap enough that its below all the flooring, that small amount of energy starts to become more and more relevant.

[MrBo @ Dec 11th 2008 5:50PM]

The only one who's gotten it right so far is potato.
1,400kW-seconds per day (the slash is a typo; get over it, Anthony) translates to 0.389 kW-hours per day.

Why list it as Watt-hours and not joules? Because that's how the power company sells power. Look at your bill. They charge you by the Watt-hour.

Since the ballpark cost of a kW-h in the US is somewhere around 10 CENTS, it does sound like a ridiculously expensive endeavor.

[sr @ Dec 12th 2008 4:56AM]

It's amazing how little most of you know about basic physics. Stuhe's right and some of you have the gall to correct him and in the process get more "highly ranked" than him. What a daft readership for a so-called "gadget" site. Keep buying gadgets because most of you have little understanding to understand leave alone design and or critique them.

[Flashpoint @ Dec 11th 2008 4:03PM]

I wonder how much of this material could be used to generate enough power for a building full of low wattage L.E.D bulbs. Maybe a Mall could power itself with a combination of this flooring and a solar roof.

[Jack Chance @ Dec 11th 2008 4:15PM]

Considering that one kW-hour is like $0.15 it is going to take a long time before they recoup the energy used to build the floor in the first place. Now, if they could get everyone marching in lockstep! frightening but more effective.

[BlurMagic @ Dec 11th 2008 4:22PM]

I guarantee if they installed this on the floor of that prison in the Phillipines, they would generate that cash back in noooo time.
http://www.youtube.com/watch?v=hMnk7lh9M3o

[Kris120890 @ Dec 11th 2008 4:03PM]

Discotheque?
Thats Old skool.

[kjb434 @ Dec 11th 2008 4:10PM]

Not if you are in France. That's still how they spell it.

[Kris120890 @ Dec 11th 2008 4:14PM]

I know I just meant its a long time since I heard someone say it.

[snacker @ Dec 11th 2008 4:08PM]

/sec per day??

[mrpysnik @ Dec 11th 2008 4:11PM]

If they all stop walking, would they get trapped inside?

[Andir3.0 @ Dec 11th 2008 4:21PM]

Run Forrest! Run!

[dreamscape86 @ Dec 11th 2008 4:30PM]

lol...

But I'm pretty sure there's no risk of people stopping in a Tokyo rail station. ;) The more relevant question would be whether the floor can still generate power with someone being trampled between the walkers and the floor...

[qTip @ Dec 11th 2008 4:54PM]

OOO. like in Walmart

[grabbydad @ Dec 11th 2008 4:35PM]

Excellent!
After generating the power to get my ticket, I can board the train.
http://www.youtube.com/watch?v=Fk2R_mqV4ts

[BratPAQ @ Dec 11th 2008 4:37PM]

i thought they were using the power to power some xmas lights?

[qTip @ Dec 11th 2008 4:53PM]

you spelled christmas wrong. It's spelled Christmas. Get it right.

[BratPAQ @ Dec 11th 2008 5:00PM]

http://en.wikipedia.org/wiki/Xmas
http://en.wikipedia.org/wiki/Abbreviation

[andres @ Dec 11th 2008 5:48PM]

WHOOSH!

[Dan Fruzzetti @ Dec 11th 2008 4:39PM]

Has anyone pointed out that for the vast expense in size, time, materials and manufacturing processes, this machine generating 1400kWsec / day is generating 0.389kWh. A fraction of a kilowatt-hour. Per DAY.

Sorry, but this product would have to improve in power output by a factor of at least 100 times before we could ever care about it. Or it would have to get so much foot traffic it would be impossible.

Maybe under cars on a bridge...

[Ataneruo @ Dec 11th 2008 4:47PM]

At least three people have already pointed that out.

[Jay @ Dec 11th 2008 4:53PM]

Yes

[Dan Fruzzetti @ Dec 11th 2008 5:44PM]

True, but to be honest I only really care about the things I say and the ways in which I say them. :P

[HunterXI @ Dec 11th 2008 5:10PM]

Oh, and that works out to 1.4 MJ / day, or 16.2 Watts. The funny thing is that the metric "watts / sec" doesn't mean what they think it does – it would actually mean "joules / second^2". They meant Watt-seconds, which is almost as hilarious (joules per second for one second). All in all, doesn't say much for Nikkei's journalists.

The real thing to bitch about isn't how miniscule that is but rather the energy required to produce these floor mats – I'm sure it greatly exceeds the energy these things will produce in their lifetimes.

[dagugscht @ Dec 11th 2008 5:39PM]

@a, @sea urchin
i know of a guy who tried to get a patent and that piece of tec. know what? didn't pass!
why? where does the energy comes from? from the cars engine. when trying to store the "lost?" energy, you actually reduce the engines efficiency by increasing the rolling resistance of the tires = more gallons/miles. so you have a engine with a energy efficiency of about 20% and make it even worse. it would be better to install a decent power plant and burn the fuel with 50%+ plus heat.

for the japanese approach. nothing more than a glorified gym. the people power that thing by stepping on it. the environmental concerns are 100% correct. no way you'll get the energy input back, ever, period.

if you go down that path, they will have trampolines at the platform so that they can produce energy while waiting.
nice side effect-> it will certainly improve the health of the commuters due to an extra workout.

[Emceay @ Dec 11th 2008 5:52PM]

Every parent should have one of these under their beds - And look at their children as flesh batteries.

[why not the LS2LS7? @ Dec 11th 2008 5:56PM]

The picture clearly shows Ws, not W/s. And isn't a Ws a Joule? Why didn't they use the proper unit?

Also, I find it odd it could be stated to generate 1400kJ per day, when the display only has 4 digits. It would max out at 9.999kJ per day.