Harnessing Energy with Piezoelectric Flooring: Materials and Setup Guide

[Wreak_Peace]

Hi!

I'm trying to find a way to use piezoelectric materials, and put them under floors or roads so that people's footsteps or a cars wheel will apply pressure on them, therefore creating an electric current.

I need to find the materials to create a small square of piezoelectric flooring, so I could step on it and attach a voltmeter/ galvanometer to it to measure how much electricity a footstep could generate.

I've heard of things like piezoelectric film, cables, and transducers..

http://science.howstuffworks.com/environmental/green-science/house-music-energy-crisis1.htm

So what are all of the materials I would need to create a setup like this?
Does anyone have an idea where I could get those materials too?

Thanks!

 

[Mbert]

Perhaps this can help:

http://www.mide.com/products/qp/qp_catalog.php"

M.

 

[Wreak_Peace]

Perhaps this can help:

http://www.mide.com/products/qp/qp_catalog.php"

M.

Thanks, but I have no idea whatsoever of which thing I should need.

 

[Wreak_Peace]

Not even my Physics teacher who has a phd knows what piezoelectricity is.. Can anybody help me?

 

[Pythagorean]

My thinking is that any substantial amount of energy you can generate is going to drain a substantial amount of energy from a human being.

So you'd have to have a lot of give in your floors to the point where it would be annoying and tiresome (like walking on a bed everywhere you go) to generate any kind of meaningful energy.

Of course, this is assuming a personal home. If you have a mall, I could see how you might save some pennies per dollar from all the traffic with only a very small energy absorption per step (so that the people don't notice it) but of course, mall's have a higher electric bill too keep up with, too. Would it be worth the installation and maintenance?

Also, could your customers potentially sue you for stealing their energy? :P

 

[Wreak_Peace]

Pythagorean, This is for a science fair, I am a 9th grader xd.
And most likely going to be applied on roads/ airport..
And yea, this is super expensive, but its still pretty cool..But now that I think of it, this is America, that could be perfectly valid case for a lawsuit..

 

[Pythagorean]

Pythagorean, This is for a science fair, I am a 9th grader xd.

Careful, that only raises my expectations nowadays.

 

[cjl]

On roads would be problematic, as it would require the road to have significant give. That would increase rolling resistance substantially, increasing pollution and decreasing gas mileage for every vehicle that travels on the road, as well as likely increasing the required road maintenance.

 

[Wreak_Peace]

It would be under the road.. Also, i think piezoelectric materials only compress a maximum of 4% or so.

And nobody's answered my questions yet :/

 

[Wreak_Peace]

Need help urgently :/

 

[Gordianus]

As far as I know, piezo ceramics have been used as pressure or force transducers but the efficiency is very low. What I men is this: I you compute the work done while compressing the piezo and compare it to integral al the voltage times the current, the former is much larger. In the sensor area this is not a problem because we're not interested in efficiency.
However I feel the project uses sound physical ideas, albeit the conversion from mechanical to electrical energy should be too low.
There are meny piezo makers. I've found these:
www.piezocryst.com/
www.piezotechnologies.com/

PS: I've never seen a piezo shaped like a tile.

Good luck.

 

[Mbert]

PS: I've never seen a piezo shaped like a tile.

Check my earlier post.

Not even my Physics teacher who has a phd knows what piezoelectricity is.. Can anybody help me?

Piezoelectricity comes from the deformation of the crystalline structure (of some materials). When the crystal is deformed, positive and negative charges forms on opposite faces of the crystal, which creates a voltage that can be alternating if the deformation is alternating (such as vibration). The inverse is also true: if an alternating voltage is applied, the piezo vibrates.

Pythagorean, This is for a science fair, I am a 9th grader xd.
And most likely going to be applied on roads/ airport..
And yea, this is super expensive, but its still pretty cool..

Not sure this is the kind of project for a 9th grader. Considering the amount of energy that can be gathered from this kind of source, using it in tiles wouldn't be very effective and could probably only light a LED.

M.

 

[Wreak_Peace]

Well, I realize its not that effective, but its for a science fair project..
If you put this in the busiest areas of an airport, I'm sure it'd be very effective.

Anyone else looking to help.. I need sources, or any places where i could obtain pre-made tiles of these, or even just helping me out in pointing out exactly what piezo component creates electricity when under pressure/ is designed specifically for it.

 

[Wreak_Peace]

I found a few senior theses/ projects on piezoelectricity..

Something about piezo coax cable.. Anybody know what this is/ how it works?

 

[Delta Kilo]

Well, I realize its not that effective, but its for a science fair project..
If you put this in the busiest areas of an airport, I'm sure it'd be very effective.

Sorry, but it does not work this way. You cannot be sure until you estimate it. Even a rough estimate will do.

Consider the distance traveled by the top edge of the tile when a person steps on it. Keep in mind most piezo materials are crystalline and don't bend well. Assume reasonable value for a person's weight. Knowing the force and the distance, estimate the amount of work done to a tile when a person steps on it (ignore the dynamics, assume the force is constant. This is only a rough estimate).

Consider the area of the area (pardon the pun), the average number of people there and how often they step. Compute average mechanical power output in watts per sq meter.

Now pluck a tiny little fraction out of thin air, that would be a proportion of the energy actually converted to electricity (as opposed to energy converted into heat and also returned back to the person due to deformation being partly elastic).

Then consider what sort of output your tiles are going to generate. Think of a way to convert short irregular pulses of unpredictable amplitude and duration into something useful. Conjure another small fraction, that would be the efficiency of your power converter.

Finally, do the math, get the answer (in watts per sq. meter), see if you like it.

 

[chrisbaird]

Sorry, the piezoelectric response of materials is extremely weak. Just strong enough that they can be used as detectors by amplifying the signal, but way too weak as an energy source, no matter how many people there are at the airport. If you are thinking of harnessing footsteps as an energy source, a much more efficient system would be hydraulic (like a pump). Put a length of rubber tubing filled with water snaking under a tile, connect to valves and a turbine that drives a generator.

 

[Delta Kilo]

Well, my point was, given very small displacement (some small fractions of a mm), even if you somehow manage to convert all availiable energy into electricity it will still not be enough to make it interesting.

 

[phinds]

It seems to me that the unstated part of your OP is that your experiment should either directly produce a useful amount of electricity or should show in some way how it could be scaled up to do so.

It is a good idea but suffers from the fact that it won't work, for the reasons others here have pointed out. I commend you for thinking of something clever to do. Now use that cleverness to recognize that you need to move on to another idea if you really want to show something meaningful.

If it's too late for this project, that is unfortunate. Perhaps you should have started earlier.

EDIT: by the way, if your prof has a PhD in one of the hard sciences (physics or engineering) and does not know what the piezoelectric effect is, I suggest you not give too much weight to anything he has to say. It is introduced in undergraduate physics.

 

[Wreak_Peace]

That hydraulics system sounds very interesting, and it probably is more viable (in a large area)
I may ask if I could maybe switch my project to that, as it might not be too late..

But also, I really don't care that right now, piezoelectric materials are very unefficient.
Maybe placing them under landing/takeoff strips at an airport would work? They'd obviously have to be relatively deep underneath the stone they have, but it would be more efficient than in the airport itself.

Although, it would be expensive to repair the system, it may be too fragile underneath that much pressure, and it would be expensive and hard to remove the landing strip and place this underneath it... But I would imagine that these landing/takeoff strips could be replaced regularly, i don't know.

 

[Wreak_Peace]

Anyways, if I would go with the hydraulic floor system, wouldn't the floor have to shift way too much? Either the floor would change positions enough for it not to be practical, or there would be too little pressure on the rubber tubes filled with water.

 

[Wreak_Peace]

According to: http://science.howstuffworks.com/environmental/green-science/house-music-energy-crisis1.htm

"One footstep can only provide enough electrical current to light two 60-watt bulbs for one second"

So that's 120 Watt Seconds
.0333... Watt Hours
3.33... x 10^-5 KwH

Atlanta Hartsfield Jackson Airport = 89 Million Visitors Ea. year..
Lets say half of them (44.5 Million) Walk a minimum of 100 steps (Wildly guessing here)

= 14,833 KwH per year.. Give or take idk, 3,500 KwH? So About 10 Megawatts a year.

Please correct me if you think I did something wrong in any of these calculations or if you think my guessing is ridiculous.
Thanks!

 

[AlephZero]

"One footstep can only provide enough electrical current to light two 60-watt bulbs for one second"

So, if that is true, and you march at 120 steps per minute, you could light up 240 watts of lanps contunuously? I don't believe that.

The 240W seems like a measure of the TOTAL amount of energy you expend in walking, judging by this site http://www.brianmac.co.uk/energyexp.htm

Take a typical value from the middle of the table of "4 Calories / minute" (really kCal). That is 4000/60 = 66 cal / sec = 66 x 4.2 = 280W.

That 280W of energy expenditure is assuming that NO extra energy is used in deflecting an extra-flexible floor. If you wanted to take out the energy to power the light bulbs, walking would require twice as much energy as before.

 

[Wreak_Peace]

So, if that is true, and you march at 120 steps per minute, you could light up 240 watts of lanps contunuously? I don't believe that.

The 240W seems like a measure of the TOTAL amount of energy you expend in walking, judging by this site http://www.brianmac.co.uk/energyexp.htm

Take a typical value from the middle of the table of "4 Calories / minute" (really kCal). That is 4000/60 = 66 cal / sec = 66 x 4.2 = 280W.

That 280W of energy expenditure is assuming that NO extra energy is used in deflecting an extra-flexible floor. If you wanted to take out the energy to power the light bulbs, walking would require twice as much energy as before.

http://www.csmonitor.com/2007/0926/p14s02-stgn.html?page

"For two architecture students at the Massachusetts Institute of Technology in Cambridge, Mass., the sound of footsteps is an echo of energy gone to waste. They figure that the stomp of every footfall gives off enough power to light two 60-watt bulbs for one second."

 

[Delta Kilo]

http://www.csmonitor.com/2007/0926/p14s02-stgn.html?page

"They figure that the stomp of every footfall gives off enough power to light two 60-watt bulbs for one second."

Well, they figured wrong. "two 60-watt bulbs for one second" is 120 Joules. That's the energy required to lift 60kg by 20cm or one step up the stairs. In other words it's the difference between walking level and climbing the stairs, who do they think are they kidding?

 

[AlephZero]

Sorry, but I don't accept articles in "Christian Science Monitor" as a reputable scientific source. As Delta Kilo said, the numbers don't add up by orders of magnitude.

 

[Wreak_Peace]

http://web.mit.edu/newsoffice/2007/crowdfarm-0725.html

And I agree with you on it not being a reputable scientific source..

 

[Vanadium 50]

Wreak Peace, the error in your argument has been shown. Repeating the same wrong number over and over (your links are all about the same story) is interfering with your learning.

Part of being smart is knowing when to ditch a wrong idea.

 

[AlephZero]

Here is something a bit more scientifically credible IMO.

They are aiming to produce 1 to 10W of power per person, though the prototype is only producing milliwatts.

http://host.madison.com/news/local/...cle_82a17e5c-cdec-11e0-a7b6-001cc4c03286.html
http://www.instepnanopower.com/

Apparently an experiment has been in progress at a train station in Tokyo for several years now, but I haven't been able to find anything substantial about it (press releases containg nonsense units like "kilowatts per second" aren't science!)

 

[Wreak_Peace]

Here is something a bit more scientifically credible IMO.

They are aiming to produce 1 to 10W of power per person, though the prototype is only producing milliwatts.

http://host.madison.com/news/local/...cle_82a17e5c-cdec-11e0-a7b6-001cc4c03286.html
http://www.instepnanopower.com/

Apparently an experiment has been in progress at a train station in Tokyo for several years now, but I haven't been able to find anything substantial about it (press releases containg nonsense units like "kilowatts per second" aren't science!)

They never mention piezoelectricity... They mention a fluid, which when compressed will create an electrical current.

 

[Wreak_Peace]

Wreak Peace, the error in your argument has been shown. Repeating the same wrong number over and over (your links are all about the same story) is interfering with your learning.

Part of being smart is knowing when to ditch a wrong idea.

The only reason I gave that link to the mit website which has basically the same stories and facts, is that the christan science monitor is not a reputable source, no offence to anybody.

 

[Vanadium 50]

The Christian Science Monitor is certainly a reputable source. Please stop posting such nonsense.

 

[AlephZero]

They never mention piezoelectricity... They mention a fluid, which when compressed will create an electrical current.

True, but the only working device that MIT students have built (according to the your MIT link) didn't involve piezoelectricity either. It was a stool with a built-in dynamo that powered 4 LEDs.

The point is, the "waste" energy from humans is not mechanical, it is heat. The heat energy available from a the feet has been measured at about 20 watts. If you want to make an efficient way to collect heat energy, you build some sort of heat engine. That's what the guys from Madison are doing, though they are also using the mechanical pressure from walking to help pump the working fluid around, so far as I can understand their website.

If you think about impedance matching and the maximum power transfer theorem, it seems rather obvious (to me) that attempting to transfer mechanical energy from a walker into the floor, before you convert it to electrical energy, will have a very low efficiency, except perhaps in two cases:

1. You make a very flexible floor, which will be difficult and tiring to walk on.
2. The "walkers" are actually jumping up and down (with straight and stiff legs), which might account for why a similar system "works" in a disco. But I'm much too old to know first hand what goes on in discos these days!

 

[Wreak_Peace]

If you think about impedance matching and the maximum power transfer theorem,

I totally understand this...
(Sarcasm, but I do get your point, its not efficient)

But I'm a stubborn person and you'd have to admit that it wouldn't be that inefficient in the busiest areas of an airport (Security Checking, Baggage Claims(Possibly on the baggage claim carousel itself?)) ..
It could also work underneath busy roads, or sidewalks, in New York..

I mentioned this earlier, but underneath takeoff/landing strips there is a potential of a lot of energy, just that it needs to be very flexible and deep underneath the stone.

It'll be really small, but in really busy areas, wouldn't all the tiny footsteps add up?
I kind of made it into a fermi question involving Atl. Hartsfield Jackson, but I'm not that good at them..

And sorry for claiming that the Christian Science Monitor is unreputable, I was just going off of what somebody else said.

 

[Vanadium 50]

I kind of made it into a fermi question involving Atl. Hartsfield Jackson

Except that you refuse to accept the answer.

This thread is done.