Is Critiquing Green Ideas Considered Taboo in the Scientific Community?

[CWatters]

I'm in two minds about this story...

http://inhabitat.com/13-year-old-ohio-girl-taps-traffic-to-generate-renewable-energy/

On the one hand it's great to encourage young engineers but how exactly is it green/ renewable?

 

[scottdave]

At first it seems awesome. But I don't consider it renewable. The energy has to come from somewhere. It would slightly slow the car down, so the engine would have to burn a little more fuel to maintain speed. And how efficient are the piezoelectric devices? For each driver, the additional cost would be tiny. But if the device is cheap enough to install, it might be more economical for the city to use these to recharge signs, rather than solar panels( at least in areas which don't get a lot of sun). It could be worth a look.

 

[CWatters]

I suppose it would be ok if only used say on the approach to a stop sign where a car would be slowing anyway.

 

[scottdave]

I suppose it would be ok if only used say on the approach to a stop sign where a car would be slowing anyway.

Great point. Since they are slowing down, they would be braking (which converting the kinetic energy to heat).
I have served as a judge on some science fairs. I always like to talk with the students to find out their understanding, and to give them tips on things they may not have considered. If I'd been judging this project, I would like to ask where the energy comes from.

 

[scottdave]

Maybe the idea could be used to power light-up shoes? http://www.robotroom.com/Light-Up-Shoes-Vibration-Sensor.html

 

[jack action]

Maybe the solutions of these kids won't solve the energy crisis, cure Alzheimer or help feed the poor, but if you require that type of criterion to be fulfilled to enter the challenge, how many 10-15 year-old (or anyone for that matter) would qualify for the challenge?

I looked at some of the presentation videos from the finalists of this challenge, and I think it's more about the effort put in the research, the experimentation and the presentation. From the official rules:

Entry Videos will be scored using the following judging criteria:

• (i) Creativity (ingenuity and innovative thinking) (30%);
• (ii) Scientific knowledge (30%);
• (iii) Persuasiveness and effective communication (20%); and
• (iv) Overall presentation (20%).

Knowing that inhabitat.com is convinced that her solution has potential, I guess that this 8th grader fully earned her points for Persuasiveness and effective communication!

 

[scottdave]

I looked at some of the presentation videos from the finalists of this challenge, and I think it's more about the effort put in the research, the experimentation and the presentation. From the official rules:

Knowing that inhabitat.com is convinced that her solution has potential, I guess that this 8th grader fully earned her points for Persuasiveness and effective communication!

I think the effort that she has put into this project is great. And she is a great communicator. I have no intention of crushing her idea. But I am saying that she needs to know where the energy is coming from, and how that affects the success of her project. I think she will go far, regardless of who wins the contest.

Thanks for sharing the link to the contest. I am interested in looking at all of the finalists, now.

 

[russ_watters]

I'm in two minds about this story...

http://inhabitat.com/13-year-old-ohio-girl-taps-traffic-to-generate-renewable-energy/

On the one hand it's great to encourage young engineers but how exactly is it green/ renewable?

I tend to agree; you can call it energy harvesting without calling it green/renewable. For a 13 year old, the idea doesn't need to be viable, but I think it sends a bad message to reward a claim that is just plain wrong in a basic way.

Hopefully she'll learn the truth gently and not become a 30 year old still believing in (and trying to sell!) Santa Claus.

 

[jack action]

I tend to agree; you can call it energy harvesting without calling it green/renewable. For a 13 year old, the idea doesn't need to be viable, but I think it sends a bad message to reward a claim that is just plain wrong in a basic way.

Hopefully she'll learn the truth gently and not become a 30 year old still believing in (and trying to sell!) Santa Claus.

I think the problem is those people who «scout» kid challenges to find solutions to complex problems. Especially if they believe and/or sell the solutions as to be viable.

 

[NTL2009]

Maybe the solutions of these kids won't solve the energy crisis, cure Alzheimer or help feed the poor, but if you require that type of criterion to be fulfilled to enter the challenge, how many 10-15 year-old (or anyone for that matter) would qualify for the challenge?

I looked at some of the presentation videos from the finalists of this challenge, and I think it's more about the effort put in the research, the experimentation and the presentation. From the official rules:

Entry Videos will be scored using the following judging criteria:

• (i) Creativity (ingenuity and innovative thinking) (30%);
• (ii) Scientific knowledge (30%);
• (iii) Persuasiveness and effective communication (20%); and
• (iv) Overall presentation (20%).

Knowing that inhabitat.com is convinced that her solution has potential, I guess that this 8th grader fully earned her points for Persuasiveness and effective communication!

IMO, the 30% for Scientific Knowledge in an issue. There should be some baseline 'gate' for demonstrating sound science, or you get a zero overall. You could score 70% with a nice presentation on a perpetual motion machine. We have far too much of that sort of thing in the world today.

My basic problem with this is she uses the term energy, but never discussed the energy being produced. Looking back, I did see she listed current with the different piezo she sampled (in fine print, and no dialog to bring attention to it), so around 1V and 6 mA for 6 mW. Fine for demonstrating the principal, but I cringe with the amount of hype between demonstrating an effect, and the leap to "cheap and easy" electrical energy production on the a scale of solving the world's energy needs! Don't tell me it is cheap and easy unless you have something to indicate that. And it does come across as 'perpetual energy' if you don't explain you are getting the energy from the cars (which might be fine, if as other's said, you are trying to slow the cars down).

Too much to expect from 13 year olds? I don't think so. Start with a sound science principal and go from there. I think the "innovative, creative and presentation" focus leads to producing a generation of snake oil sales-men and women.

I know it's not the goal of something like this, but I'd be more impressed with these kids demonstrating why a certain idea won't work. Build critical thinking. Show the difficulties of installing these in areas with snow and ice, what will happen when cars run over them, will they wear the car tires, etc. I remember learning the lesson that sometimes the most important thing is to know what not to do. I fear that all this positive reinforcement of everything a kid does is killing critical thinking.

OK, I know I sound like a curmudgeon, but it is important. And actually positive, we need to be critical to make good progress, or we waste our time on the dreams that lead no where.

 

[scottdave]

I think it would be cool to go to this contest and see the different projects and talk to the participants about what they are doing and what they may have forgotten to include. Hopefully to help them to improve themselves. I enjoyed judging at the science fairs. I have been a judge at both the Jr High (7-8 grade) and High School level. I have seen some good and some mediocre projects at both levels. I have also seen some Junior High projects which put some of the high school projects to shame. The website for the contest shows that there is some great thinking going on at this age level. It gives me optimism about our future.

 

[The Wizard]

@ CWatters: Green and renewable as it functions every time the Piezo is subjected to pressure, which generates electricity.

@ scottdave: The vehicle would not have to slow down or use more fuel as the Pressure pad would be mounted in the road surface, not on the vehicle, so that everytime a vehicle drives over it the pad will produce electricity.

How much electricity would be produced will be dependent on the size of the pressure pad and how many Piezo cells would be mounted in it and how many pressure pads would be inserted into the road surface.

I am currently working on a project that uses Piezo pads to operate switches.

 

[mfb]

@ CWatters: Green and renewable as it functions every time the Piezo is subjected to pressure, which generates electricity.

A coal power plant generator functions every time it is spun, that doesn't make it green or renewable.

@ scottdave: The vehicle would not have to slow down or use more fuel as the Pressure pad would be mounted in the road surface, not on the vehicle, so that everytime a vehicle drives over it the pad will produce electricity.

In general the vehicle will need more power. If the road gets pushed down by the wheel but doesn't return that elastic energy later the car will need more power to drive over the road.
If you harvest vibrations, on the other hand, you can do that without increasing the car power.

A main problem with all these ideas is their low power. If you have a device that can produce 1 W (that is a very large power for vibration harvesting) for 30 years, how much money can you spend on it to make electricity at a market-competitive price? Make a guess.

Spoiler

About $5. Establishing the grid connection costs more already - a device that produces 1 W is simply not worth the installation even if the device and its power source are free.

 

[russ_watters]

In general the vehicle will need more power. If the road gets pushed down by the wheel but doesn't return that elastic energy later the car will need more power to drive over the road.

The way I like to describe this is that the car is constantly trying to drive out of a depression. So it looks like it is driving on flat ground, but is really driving uphill.

And, of course: never forget conservation of energy!

The key problem is this:

@ CWatters: Green and renewable as it functions every time the Piezo is subjected to pressure, which generates electricity.

Your unfinished logic process here is that the device doesn't need to move or deform for it to work. You're looking at the wrong side of the coin(or maybe just half?): it is the deformation, not the pressure, that causes the electricity to be generated.

 

[NTL2009]

...
A main problem with all these ideas is their low power. If you have a device that can produce 1 W (that is a very large power for vibration harvesting) for 30 years, how much money can you spend on it to make electricity at a market-competitive price? Make a guess. ...

And at that payback, it would be better financially to invest the money elsewhere. As far as environmental payback, it's unlikely it would payback the energy/resources to construct and maintain it for 30 years. And if that's the case, it isn't 'green' at all - it's negative 'green'.

 

[JBA]

We have had a similar discussion about power losses on this type of power generation and in both cases the issue that is being ignored is that the power loss driving over the hard surface of a piezoelectric plate is from a practical standpoint is essentially zero because the deflection of this type of device is comparable to driving on an existing concrete or asphalt surface so the equivalent power recovery is essentially 100%. At that point, the issue of power output then come into effect as to the economics of installing such a system vs. alternative power supply options.

In the case of replacing a section of existing road where there is also an existing power distribution system there is one set of economics; however for a location that does not have either an existing power grid or road and the power generated is to be used locally to that point for applications such as safety lighting there is a whole different set of economics involved (not say that the comparable cost for alternatives such solar and/or wind power shouldn't be included in evaluating those cases as well).

I feel many times we can make the mistake of taking a geocentric view applicable to our own developed environments when, in fact, those conditions exist on only very minimal region of the world's populations. Likewise, even small contributions to improving the environmental methods by which we generate power can, when accumulated, make an important contribution.

 

[mfb]

the power loss driving over the hard surface of a piezoelectric plate is from a practical standpoint is essentially zero

Compared to the power of the car, the additional power the car needs is essentially zero. But compared to the car the electricity produced is essentially zero as well. It doesn't make sense to neglect a loss and highlight a gain of the same value (actually lower, because the conversion is not 100% efficient).

These systems can be interesting if low power is needed at remote locations, sure. But connecting them to the grid doesn't make sense.

 

[scottdave]

I don't recall her saying in the video that it was for developing countries, but the description on the contest page does mention that. So yes it can have some applications there. But I would like to see them stay away from terminology like renewable.

 

[krater]

I feel many times we can make the mistake of taking a geocentric view applicable to our own developed environments when, in fact, those conditions exist on only very minimal region of the world's populations. Likewise, even small contributions to improving the environmental methods by which we generate power can, when accumulated, make an important contribution.

You're forgetting something as it applies to something like the pizeo road concept. To focus solely on the locales that invention x is desired to be applied neglets the fact that frequently invention x will require production facility the likes of which exist on actually a vanishingly small proportion of the globe. There could be many reasons for this, resources or necessity of a modern economy for example, but it falls in line with what I always enjoy inserting into any discussion on solar...

Tell me, if pizeoelectric roads were really that great a return on investment... is it likely that pizeo plate factories will be powered by the roads their employees drive to get to them? Or is this wonder product easily assembled in an afternoon with stuff out of the garage? Don't forget, coal power built coal power. It also built nuke. And hydro, and largely wind and solar. Essentially all the raw material, all the tooling, all the flourescent lights in the engineering offices owed to history's largest energy source. And in the current energy market it will be building a large share of whatever we end up going with next. So we really need to get serious about deciding which choice is worth it. Pizeo roads are not taking us in that direction, and nobody should be trying to lobby for them anywhere.

 

[JBA]

There was also a time when the common knowledge was that neither wind or solar power would ever be practical. At this time, the best thing for us to do is continue to encourage and investigate all possible combinations of existing and proposed power sources, present and future, even if they are "not economical" at their current state of development.

The idea that there can be a single best source of power for all regions of the globe is a folly. To paraphrase the President of GE Power Systems, "We cannot continue to depend upon our current centralized power production and distribution grids because they are too vulnerable to massive systemic failures. What we need is an array of interconnected distributed mini and micro grid power sources". Fortunately, due the current spreading development of solar and wind power around the globe that is exactly what is now happening; but, we should not assume that even those will the paramount systems of the future.

Due to the spread of technological knowledge around the globe our rate of exponential technological growth and investigation will continue seeking new and innovative sources of power, even if some turn out to be deadends. The fluorescent lights mentioned above are good example of a deadend technology now being replaced by those once "little tiny low power" LED's.

What we are now learning is that the once holy grail of lowest cost $/Btu basis for power sources does not necessarily represent their total cost once their damage to world health and environment are included in the equation.

What was yesterday or is today is not what must or will be tomorrow.

 

[The Wizard]

From all the replies posted to date only JBA has recognised what is proposed by the use of Piezo electrics to generate power which is renewable every time the piezo disc is subjected to mechanical pressure. The disc movement required to generate electricity is aprox. 0.1mm or 0.0039 in.
The amount of power produced will be subject to the size of the disc and how many discs are included in a pad.
Unlike Solar or Wind powered systems they are not restricted by weather conditions or lack of daylight.
As to the limited power output, do you need a x Megawatt Coal / Nuke powerstation, not to mention the costs involved getting the power to a remote village maybe 1000 miles away, to power a few LED's?

The idea is not to supply a power grid, it is to provide electricity on a very local level maybe down to a single dwelling just needing power for a few LED lamps.

As to the pressure needed, most road surfaces are mallable and deflect when a vehicle rolls over it so it would not be a problem to incorporate a pressure pad in the road surface. In fact, russ_watters even made a reference to this point in his post about driving uphill all the time due to this "Deflection"

For a young woman to come up with an alternative idea that could eventually provide power, even in a very limited form, in areas of the world which do not have any power at this moment in time is, in my opinion, certainly worthy of the prize.

 

[CWatters]

.. the issue that is being ignored is that the power loss driving over the hard surface of a piezoelectric plate is from a practical standpoint is essentially zero because the deflection of this type of device is comparable to driving on an existing concrete or asphalt surface so the equivalent power recovery is essentially 100%.

If I've understood you correctly you are saying that the rolling resistance when driving over piezoelectric plates is the same as the rolling resistance when driving over concrete or asphalt?

 

[The Wizard]

@ CWatters

As the plates would be essentially "buried" in the road surface, the road surface would not alter the rolling resistance of the vehicle.
In addition, even if there was a difference in the surface material the effect would be absolutely minimal and certainly not detectable.
Rough Example: Car tyre surface in contact with the road surface = tyre tread width by length of tyre contact with road surface or numerically say 215mm x 180mm. For purpose of travel only the length is relevant 180mm. So a vehicle traveling at 70 kms/hr (43.5mph) will cover 70000 mtror 229658 feet., that extends to 70.000.000 mm or 2.755.905 inches in 60 minutes. In seconds that means the vehicle will travel 19444 mm in 1 second.
If the pad was 720mm wide the tyre contact with the pad would be 0.037secs, as I stated earlier, not detectable and would not change the normal rolling resistance of the tyre to road surface.

 

[256bits]

@ CWatters

As the plates would be essentially "buried" in the road surface, the road surface would not alter the rolling resistance of the vehicle.
...

I think what you are saying is that the road/tire deform anyways and produces heat.
The piezoelectric device is capturing the deflection of the road and making a capture of that energy as electrical, rather than having an increase in temperature of the road.

 

[The Wizard]

@ 256bits,

the Piezo device itself actually only needs a deflection of about 0.1mm which is enough to produce the electrical impulse. As roads deflect under weight of the vehicles passing over the surface, the movement required to actuate the device is a given fact. Temperature does not play any role in the piezo's ability to produce electricity. The deflection of the road surface is not producing any electrical power, it is only allowing the pressure required to be transmitted to actuate the piezo device.

In order to clear up any misunderstandings, the piezo device is a composition of various components which normally form a flexible flat surface circular part with a plus & minus cable attached. The piezo is deflected from its normal flat status by pressure applied to the center which in turn generates an electrical current. When the pressure is relieved the piezo returns to it's flat state until the cycle is repeated. As most road surfaces are mallable they deflect when the weight of a vehicle passes over it, this deflection will allow a piezo device to function even when mounted below the actual road surface.

On a side issue, I did some work last year on suspension systems where piezo devices are being considered as an on-board electrical source when mounted on the vehicle shock absorbers.

 

[mfb]

There was also a time when the common knowledge was that neither wind or solar power would ever be practical.

The equivalent would be "fan-powered wind turbines and light bulb powered photovoltaics are not practical" - and that is still common knowledge. That doesn't mean optocouplers would be useless, but they don't power an electricity grid.

For a young woman to come up with an alternative idea

The idea is not really new.
It is a nice project to build a prototype (probably not the first one).

Normal roads deform as well, but that deformation is mainly elastic - the asphalt absorbs some energy and gives it back to the wheel. With the piezos the restoring force is reduced, rolling resistance increases.

 

[The Wizard]

@ mfb,

the force required to deflect a flexible part by 0,1 mm is so small you would need a specialist with high tech equipment to measure it and as it also returns to its original position it does not detract from the road surface returning to its original state so there is no loss of force and it certainly will not increase the rolling resistance of any vehicle. Any deformation of the road surface created by the weight of a vehicle will not be given back to the wheel as the wheel would have already left the point of deformation before the return to the original state would exist, so that is an invalid argument.
The road surface (asphalt, concrete, mud, stone etc) is not receiving energy, it is receiving pressure created by the weight of the vehicle being driven over it.
Should the surface deformation be converted to energy in another form such as heat etc. has absolutely no bearing on the piezo function.

With regard to your other comment her idea is not to supply power to a power grid, she is talking about supplying power to light a LED lamp in a house in areas where electricity does not exist in any form except maybe a non-rechargable battery.

As some background information, I spent 10 years in Heavy Vehicle Technical Sales which also involved having to calculate rolling resistance of different tyres (sizes, tread profiles, ect) on different road surfaces with different gradients in order to select appropriate Gearbox, Axle & Final Drive ratios for different applications, so when I make a comment regarding Rolling Resistance between various road surfaces and vehicle tyres, I know what I am talking about.

 

[jack action]

The road surface (asphalt, concrete, mud, stone etc) is not receiving energy

Oh, yes it is. If the piezo produces energy, it means that there was an energy input somewhere. And the only energy source here, it is the car engine. The pressure creates a force and a displacement. Both combined creates work, which is a form of energy.

When you are rolling on a road, it's like rolling on a series of vertical springs. As you roll over it, the springs compress, requiring some energy, and then releases the energy as the tire passes by and the springs decompress.

Two possibilities exist:

1. The entire energy stored in the road is used to push back the tire as it passes by. That would mean no losses, which is a very unlikely scenario. But if that scenario was true, a piezo would necessarily take additional energy from the rolling tire.
2. The energy stored is partly or entirely dissipated into some damping, one way or another. Most likely scenario. In this case, a piezo can recover the damped energy. But if you install a piezo on the road, that doesn't mean it doesn't take some additional energy from the rolling tire either (or even that it effectively take any damped energy at all). That is because a piezo is an additional spring/damper by itself. I guess one should take some very precise road and tire temperature measurements to confirm how much wasted energy was recover.

The problem with piezo is that - if it doesn't recover the damped energy - it takes the energy from the car engine, as little as it is. And if your car is powered by an internal combustion engine, it means that you can use an electric generator powered by an internal combustion engine that will necessarily be more fuel efficient to generate that same power the car engine/piezo combination produces. So even if you want to use this in a remote area, in such a case, the fuel used by all cars passing by would cost more (both financial and emissions) than the fuel used by an equivalent electric generator.

But all that depends on how much damped energy is actually recovered.

 

[NTL2009]

@ mfb,

the force required to deflect a flexible part by 0,1 mm is so small you would need a specialist with high tech equipment to measure it and as it also returns to its original position it does not detract from the road surface returning to its original state so there is no loss of force and it certainly will not increase the rolling resistance of any vehicle. Any deformation of the road surface created by the weight of a vehicle will not be given back to the wheel as the wheel would have already left the point of deformation before the return to the original state would exist, so that is an invalid argument. ...

For this to be true, the road-bed that supports the piezo elements would need to be infinitely stiff, or more practically, say provide only 20% the deflection of the normal road surface to get 80% of the effect. How expensive would such a mechanical support be to construct? How much energy would it take to construct/install/maintain it? You don't get something for nothing.

edit/add: If that works, maybe we should just make stiffer roadbeds then, and reduce the energy wasted by all vehicles, all the the time they travel. We'd save even more because we wouldn't need to convert anything, it would all be a direct savings of fuel.

With regard to your other comment her idea is not to supply power to a power grid, she is talking about supplying power to light a LED lamp in a house in areas where electricity does not exist in any form except maybe a non-rechargable battery. ..

But in the intro, she certainly does compare this to world-wide power, and the grid, and how we are running out of oil and wind & solar aren't enough, etc. If she really presented this as a niche power source (many 'impracticable' ideas can be practical for a remote, low power device), that would be different.

... In order to clear up any misunderstandings, the piezo device is ... As most road surfaces are mallable they deflect when the weight of a vehicle passes over it, this deflection will allow a piezo device to function even when mounted below the actual road surface. ...

I don't think there is any confusion among the critics here about what a piezo is or how it functions. But you seem to be telling us you can perform work (force times distance) and produce energy without consuming any energy, and that is perpetual energy territory. Or alternately, you are trying to tell us the energy consumed is small, but that tells us the energy produced is even smaller.

What is the efficiency of a piezo in this configuration? I saw some refs to ~ 40% at resonance, I assume it would be far lower in this application. Here's an interesting note from wiki (emphasis mine):

A similar idea is being researched by DARPA in the United States in a project called Energy Harvesting, which includes an attempt to power battlefield equipment by piezoelectric generators embedded in soldiers' boots. However, these energy harvesting sources by association affect the body. DARPA's effort to harness 1–2 watts from continuous shoe impact while walking were abandoned due to the impracticality and the discomfort from the additional energy expended by a person wearing the shoes.

... On a side issue, I did some work last year on suspension systems where piezo devices are being considered as an on-board electrical source when mounted on the vehicle shock absorbers...

Now that is interesting and a horse of a different color, I'd like to hear more. It seems to me a car suspension can be (or are?) designed to absorb energy (I couched that, as I'm thinking that theoretically, the spring/absorber return all energy to the system?). So if converting some of that energy from mechanical to electrical can be part of the damping, it is workable. Whether it makes sense from a power/weight/cost/size standpoint is another matter, but it would be interesting to see the numbers behind it.

 

[NTL2009]

@ mfb,
the force required to deflect a flexible part by 0,1 mm is so small you would need a specialist with high tech equipment to measure it ...

I just re-read this after submitting my post, and I must say "Wait a minute! Isn't this an absolute contradiction??!"

We can't get any more energy out of something than we put in, right? Yet, you say "It would take a specialist with high tech equipment to measure it (the force that is so small that is input to the system)". But you propose that the presenter is correct that we can get meaningful energy out and do it "cheap and easy".

Not adding up, is it? Time for a review of the laws of physics?

 

[scottdave]

So I was reading about the contest. It looks like each finalist is assigned a mentor to work with. With some guidance from the mentor, the contestant comes up with a solution to some problem, which may or may not be related to the original submission. Also, it appears that most of the work that goes into the initial idea and presentation, is intended to come from the student.

In reality, this contestant probably has already been made aware of many of the issues associated with this type of energy generation. I am glad that Discovery and 3M takes this approach.

 

[NTL2009]

There was also a time when the common knowledge was that neither wind or solar power would ever be practical. ...

I see that as a straw man argument on several levels. First, it isn't 'common knowledge' that matters, it is the knowledge and experience of those who have expertise in the area. And those with expertise should fully realize that solar and wind (like anything else) are the right answer in the right situation. It's why solar panels are used to power satellites, but the Voyager spacecraft was powered by nuclear decay and thermo-couples (very inefficient, but Voyager would travel too far from the Sun for solar power). The right tool for the right job.

... At this time, the best thing for us to do is continue to encourage and investigate all possible combinations of existing and proposed power sources, present and future, even if they are "not economical" at their current state of development. ...

Agreed. And we should recognize the difference between investigating possibilities and hyping some impractical application. No one is served by the latter (except shysters).

... The idea that there can be a single best source of power for all regions of the globe is a folly.

True, but another example of a logical fallacy. We can state a problem to be serious, but it does not follow that any solution we throw at it is a good one.

Proposed solutions should not be looked at in a vacuum (of knowledge that is, I guess if you are designing vacuum systems... ). They need to be compared to other solutions, and the best overall for the application is chosen. Not anything that 'works'.

...Due to the spread of technological knowledge around the globe our rate of exponential technological growth and investigation will continue seeking new and innovative sources of power, even if some turn out to be deadends. The fluorescent lights mentioned above are good example of a deadend technology now being replaced by those once "little tiny low power" LED's. ...

But it is also that technological knowledge that we possesses that allows us to identify which areas might have some potential, and which ones are certainly a dead-end. LEDs were very practical for a long time at lower power levels. But the technological knowledge we possesses told us that they could be scaled up, it took time and resources to do that, but it was clear it wasn't an absolute dead end, it had potential, and that potential is being realized. And it was clear that the CFL had limits, so there is where that comparison of technology that I mentioned comes into play (I'll skip any lame 'joke' about vacuum and CFLs for now - hah-hah).

... What we are now learning is that the once holy grail of lowest cost $/Btu basis for power sources does not necessarily represent their total cost once their damage to world health and environment are included in the equation.

What was yesterday or is today is not what must or will be tomorrow.

And we got to that point, and will advance, by applying critical thinking and our technological knowledge to new ideas, not chasing Unicorns.

 

[russ_watters]

We have had a similar discussion about power losses on this type of power generation and in both cases the issue that is being ignored is that the power loss driving over the hard surface of a piezoelectric plate is from a practical standpoint is essentially zero because the deflection of this type of device is comparable to driving on an existing concrete or asphalt surface so the equivalent power recovery is essentially 100%.

@mfb took the tack of assuming you're rounding the "input" to zero while claiming the benefit of the output, but I'll challenge it more directly: what you are saying (as a reason) just isn't true.

Piezo devices are in general not as hard as a concrete road and the hardness and energy generation ability of the devices are inversely proportional, meaning you have to decrease the hardness (increase the rolling resistance) to increase the energy harvesting. The goals and properties are opposites of each other.

Now, I suppose that there is a cross-over threshold where you can say a harder ceramic might have lower rolling resistance than a concrete road, but that still doesn't help you because the act of harvesting the energy creates an offsetting energy loss in the tire/car. In other words, if you have a system installed and harvesting energy, you save more energy by turning it off than you harvest by using it.

There was also a time when the common knowledge was that neither wind or solar power would ever be practical. At this time, the best thing for us to do is continue to encourage and investigate all possible combinations of existing and proposed power sources, present and future, even if they are "not economical" at their current state of development.

Though people (including me) have used synonomous words like "economical", "viable" and "practical", I want to emphasize that the reason I disagree with awarding the prize is not because of those terms. They aren't releant here because this idea is theoretically flawed as a violation of conservation of energy. People should not just research anything, but should know when the path they are on is a complete non-starter/dead end and choose a different path that doesn't require violating the laws of physics to work.

 

[The Wizard]

@NTL2009
quote "edit/add: If that works, maybe we should just make stiffer roadbeds then, and reduce the energy wasted by all vehicles, all the the time they travel. We'd save even more because we wouldn't need to convert anything, it would all be a direct savings of fuel."

your comment is very true, harder roads would indeed save a large amount of fuel but the initial road building costs would be higher and the division of costs would be hard to share. Example the state or city is responsible for the road maintenance costs but the fuel savings would be in the pocket of the vehicle owner and the general savings in the economy because of lower fuel imports etc.

To answer your remarks about the use of Piezo units on the suspension, the Piezo acts as a switch to control electronic suspension components, the power generated is simply used to trigger a Canbus signal.

Regarding your comment of energy input, the vehicle weight say 2 tons spread over 4 wheels is 500 kilos per wheel pressing down over an tyre area of roughly 50 cm² so 10kg per cm². Take your 1st. finger which has about 1 cm² area at the tip and press on a household scale and see how much force you need to equal 10kgs, then repeat the exercise using a I-phone button (located at bottom of screen display) which moves about 1mm which is 10 times the distance required to trigger the Piezo.

The force required to trigger the piezo is so negible compared to force already being excerted by the vehicle on the road surface that it is virtually unmeasurable.

 

[The Wizard]

@ russ_watters,

as piezo parts are made of metal and hardenened ceramics they are just as hard if not harder than concrete or asphalt or mud or stone road surfaces so your statement is not true.
Deformationor Deflection as it is known, of a road surface varies according to a lot of factors and the deflection rate decreases with the depth and materials used in the substructure. There is no change in the rolling resistance between the tyre and road surface if you mount a sub-surface device,the co-efficients involved do not change, especially where a deflection of only 0.1mm is involved.

 

[The Wizard]

@ jack action,

the energy produced by the cars powertrain propels the vehicle over the road surface. Depending on a large number of factors, size of tyre, tread pattern, road surface material, gradient, engine output, gearing, use of accessories define how much energy is required to achieve a given speed and maintain it.

As the vehicle is driven the tyres create friction between the road surface and the tyre which produces heat. The vehicle also creates another power source and that is weight which presses down on the road surface causing Deflection. This deflection has nothing to do with heat of any kind, it is a simple mechanical reaction to the force being applied from above. If the force being applied already exceeds the force required to move a sub-component a minimal amount of 0.1mm it is a zero rated byproduct.

The idea of using the Piezo is the Zero emissions, by using a fuel based generator you have Co² emissions and noise.

 

[russ_watters]

If that works, maybe we should just make stiffer roadbeds then, and reduce the energy wasted by all vehicles, all the the time they travel. We'd save even more because we wouldn't need to convert anything, it would all be a direct savings of fuel."

your comment is very true, harder roads would indeed save a large amount of fuel but the initial road building costs would be higher and the division of costs would be hard to share. Example the state or city is responsible for the road maintenance costs but the fuel savings would be in the pocket of the vehicle owner and the general savings in the economy because of lower fuel imports etc.

Since the costs are borne by the drivers either way, it doesn't make much sense to try to generate more in taxes by purposely making cars less efficient. Instead, tax rates should be adjusted to account for increases in fuel efficiency -- which they are.

To answer your remarks about the use of Piezo units on the suspension, the Piezo acts as a switch to control electronic suspension components, the power generated is simply used to trigger a Canbus signal.

Are you saying that's how they are actually used today? That's fine, but a quick google tells me people are indeed researching energy harvesting in the shocks.

Regarding your comment of energy input...

The force required to trigger the piezo is so negible compared to force already being excerted by the vehicle on the road surface that it is virtually unmeasurable.

It isn't clear to me why you think this matters. The difficulty in measuring a small variation of a large number (on the input) vs a small number by itself (on the output) doesn't impact the physics of the situation.

You are aware that conservation of energy applies and that therefore negligible input energy results in negligible output energy, right? A separate post tells me that you may not accept the role of energy conservation here:

The vehicle also creates another power source and that is weight which presses down on the road surface causing Deflection. This deflection has nothing to do with heat of any kind, it is a simple mechanical reaction to the force being applied from above. If the force being applied already exceeds the force required to move a sub-component a minimal amount of 0.1mm it is a zero rated byproduct.

It sounds to me that you are saying you can extract output energy from this process with no additional input energy. Is that what you are saying? If that is what you are saying, it is a direct violation of conservation of energy.

Consider a spring (because that's what we have here). If you push this spring down 1m with a force of 2N, you store 1J of energy. When you release the spring, it gives 1J back. There is no energy left over to extract from the system.

If, instead, you add an energy harvesting device (an electric generator of any type), what happens is the force required to compress the spring goes up and the difference in force time distance is the energy that can be harvested. The input rises to provide the output. That's what is happening here (though for the piezo it is more deformation, not more force, that provides the output).

@ russ_watters,

as piezo parts are made of metal and hardenened ceramics they are just as hard if not harder than concrete or asphalt or mud or stone road surfaces so your statement is not true.

The most common piezo material is plastic, and "metal piezo" sounds like a contradiction in terms. Could you provide a link to such a device? I'm aware of ceramics. I probably should have set this asside because I don't want it to get in the way of the more direct problem I was discussing:

Deformationor Deflection as it is known, of a road surface varies according to a lot of factors and the deflection rate decreases with the depth and materials used in the substructure. There is no change in the rolling resistance between the tyre and road surface if you mount a sub-surface device,the co-efficients involved do not change, especially where a deflection of only 0.1mm is involved.

In the scenario you are describing you replace a piece of a road with a piezo material with the same stiffness. The catch is, the stiffness drops when you plug it into collect the electricity. So when you first build the road it feels identical, but then when you turn on the energy harvesting, the rolling resistance goes up.

 

[russ_watters]

Now that is interesting and a horse of a different color, I'd like to hear more. It seems to me a car suspension can be (or are?) designed to absorb energy (I couched that, as I'm thinking that theoretically, the spring/absorber return all energy to the system?). So if converting some of that energy from mechanical to electrical can be part of the damping, it is workable. Whether it makes sense from a power/weight/cost/size standpoint is another matter, but it would be interesting to see the numbers behind it.

I own a pair of skis that are equipped with this. They have LEDs on them that light up when skiing over rough terrain (or if you whack them with your knuckles), dissipating the vibrational energy.

This is, of course, why they are also used in microphones.

For car shocks they offer better dampening and energy production simultaneously.

 

[russ_watters]

Er, I missed this before;

Any deformation of the road surface created by the weight of a vehicle will not be given back to the wheel as the wheel would have already left the point of deformation before the return to the original state would exist...

That's the loss! With an elastic road surface, most of the energy of deformation is returned by the road pushing the wheel back up, just like in the spring example in my previous post. With a piezo(like a memory foam mattress), you decouple the input and return, and the difference is the energy loss!

 

[JBA]

OK, I get point but even the piezo chip will have some elasticity and I certainly don't mean to imply that there is 100% free energy to be gained here. So let's just say that this is another potential means of delivering energy to a location where installing the wiring or expanding or installing a power grid is not feasible or desirable; or, even if it is simply for aesthetic purposes, such as a number of upper class neighborhoods that have demanded underground power distribution systems to eliminate power poles and overhead wring in spite of its higher installation and potential maintenance costs). There are currently piezoelectric walkways, and bike path sections already operating in parks in Europe where this technology places the energy generation burden directly upon the users (not the power grid) for the safer lighted pathways that benefit those users.

As to the economics of the process, in that respect, there are too many current technologies that were "too expensive" (the cell phone as an obvious latest example, that in their earliest stage was too expensive for general population access). Thankfully technology marches on and once a new concept is brought to light then the world of technology becomes aware of it and it attracts those who are interested, or see a potential, begin to seek answers to improve that technology. As soon as we start to impede the flow of "look at this" or "what about this" scenarios based on something as simplistic as "it is just not economical" or "I can't see any future in that" we are seriously impeding scientific investigation; and, that is exactly what has been happening across this country in many industries as the corporations operate with their total focus on satisfying the investment community.

Thankfully, we still have Steven Jobs, Bill Gates and Elton Musk type individuals that are willing to take the longer view. If the short term "we have to meet the investor's quarterly profit projections" goal now driving our corporations had been historically allowed to control our global technological development then we would still be lit only by the sun and moon and traveling by foot. To paraphrase an old short quote "it was a brave man who mounted that first horse"; but, apparently he thought it was worth the risk.

With regard to the piezoelectric shoes, while making the sensors large enough and flexing them far enough to get usable power for such ideas as powering electronic accessories may not be worth the energy required from the user; using that technology to power small LED type shoes that can make children and/or runners more visible at night might be worth the energy penalty. It all has to do with individual possible applications.

As someone who spent more than half of my 40 years in new product development engineering, I have seen too many examples of "hell, that could never work" ideas turn into "well, damn, will you look at that" results.

 

[jack action]

The vehicle also creates another power source and that is weight which presses down on the road surface causing Deflection. This deflection has nothing to do with heat of any kind, it is a simple mechanical reaction to the force being applied from above. If the force being applied already exceeds the force required to move a sub-component a minimal amount of 0.1mm it is a zero rated byproduct.

The energy source with a weight $mg$ is called potential energy and it is equal to $mgh$, where $h$ is the 0.1 mm you are talking about. Two possible scenarios:

1. The car must go «uphill» 0.1 mm and then will sunk under its own weight to go back to the road level;
2. The car will sunk 0.1 mm when passing over the piezo and must «climb out» of the hole to go back to the road level.

Either way, the car must climb a small hill when it goes over a piezo and that will necessarily require wheel power.

You cannot repeatedly create energy with a weight without someone lifting it between cycles.

Even if you tell me the car will not rise, but only part of the tire will deform, still this will necessarily increase the rolling resistance of your tire, no matter how insignificant you think it is. By comparison, the power produced by the piezo will also be insignificant compared to the car power.

 

[mfb]

@JBA and @The Wizard: You keep shifting the goalpost around. In some posts you make the system inefficient to highlight that it wouldn't have an effect on the car, in other posts you make the system efficient to get some energy out. You cannot have both.

As someone who spent more than half of my 40 years in new product development engineering, I have seen too many examples of "hell, that could never work" ideas turn into "well, damn, will you look at that" results.

I'll bet that none of these examples violated conservation of energy.

Shifting things from the "that doesn't work" category to "we did it" is part of the job for every scientist, but if it violates fundamental laws of physics you should have extraordinary evidence for such a violation, and you cannot prove this violation using the laws you try to violate.

 

[russ_watters]

There are currently piezoelectric walkways, and bike path sections already operating in parks in Europe where this technology places the energy generation burden directly upon the users (not the power grid) for the safer lighted pathways that benefit those users.

Fine. Like I said, it's the just incorrect marketing that would lead me to deny her the prize. I can envision scenarios where it is worth the trade-off and know of other energy harvesting devices (indoor "solar" power, flow powered devices) that are successful and therefore proven worth the trade-off. Get rid of the "green" label and market it honestly as a "leech" and I'm onboard.

 

[russ_watters]

I'm going to expand on @jack action's lead and go into some detail on the nuts and bolts of rolling resistance and how exactly a piezo cell could be made to impact it.

Rolling resistance has 3 somewhat inter-connected components:
1. Inelastic deformation of the tire.
2. Kinetic friction due to slippage due to deformation.
3. Inelastic deformation of the ground.

Obviously, #3 is the one we are concerned with. In general/for a quality road, it is a couple of orders of magnitude smaller than the other two. But it works identically to #1. Here's how it works:

As described, an elastic object is like a bunch of little, connected springs. Apply a force and the springs compress. Release the force and the springs expand back to their original length. For the most part, energy is conserved in this process and the spring gives back almost all of the energy it absorbed. Applied to a car, the tire and road are literally shoving each other out of the way, but then they both rebound and push each other back, recovering the energy it took to shove each other out of the way. In other words, we said the car is basically climbing a hill all the time. Well, that's what the front of the tire is doing. The back of the tire is traveling down that hill (er - the previous hill).

But springs, roads and tires are not perfectly elastic. There is a component of inelasticity, which means that when they spring back, they do so imperfectly: with less force than it took to compress them. That means the hill they are rolling down isn't as steep as the hill they are driving up. The rolling resistance is the difference between the compression force and restoration force (adjusted for the angle of the contact to get it in the direction of motion of the car).

A simple piezoelectric device you can buy and play with for a couple of bucks is just a strip of plastic, to be used as a vibration sensor. Flick it and it vibrates - and it has a certain inelasticity that dissipates the energy and causes it to eventually stop vibrating. But otherwise, like the road rebounding, this is a pretty elastic situation.

Now, when you hook the device up to a circuit, you change its mechanical properties. How exactly depends on the circuit, but I'll give a simple example that dovetails well with what we are discussing. Let's say that for the deflection part of the cycle you leave the circuit open. At max deflection, you have a certain voltage and charge available and at that moment you shunt it to something that can harness it. What you just did is to siphon-off some of the elasticity of the device, making it rebound with less force and lower amplitude.

Applied to a road, the connection should be obvious: When you implant the device in the road, you can say the elasticity is the same as the concrete you replaced, if you choose it that way. But when you turn it on to extract the energy, the impact is to not rebound as well, opening a new gap between the compression and the expansion, creating new rolling resistance.

 

[NTL2009]

OK, I get point but even the piezo chip will have some elasticity and I certainly don't mean to imply that there is 100% free energy to be gained here. So let's just say that this is another potential means of delivering energy to a location where installing the wiring or expanding or installing a power grid is not feasible or desirable; ...

I think the critics here have said all along that efficiency isn't the primary constraint for remote power. But the presenter put this in the context of the world's energy supply. That is the issue.

... As to the economics of the process, in that respect, there are too many current technologies that were "too expensive" (the cell phone as an obvious latest example, that in their earliest stage was too expensive for general population access).

Oh please. Now you've touched on a hot button.

I worked on the pre-cellular tele-comm equipment (IMTS). I worked with the R&D engineers to deliver the equipment for the initial Washington-Baltimore cellular trials. I worked on the teams that brought you the first portable cell phone, and the first pocket-sized cell phone. I have sat and talked with the key players in the cell phone industry.

Not every new idea follows the path of cell phones, computers, semi-conductors, etc. Gordon Moore himself has addressed this fallacy. Just because our tablets and smartphones today have more power than a room sized computer back in the day, is no reason to think everything will progress at that rate. That tech had an extreme amount of potential growth before hitting the limits of physics, unlike most other technologies.

Bell Labs was working on the concept of the cell phone years (decades?) before the technology existed to make it feasible. Why? Because they could see the progress in technology, and could see that there was a pathway towards achieving this. They knew it was complex, so they started working through the concepts, realizing that it was likely that one day, the technology would catch up, and they wanted to be ready.

If you can show us there is a pathway for piezo elements in a roadway, to someday be viable as anything beyond niche applications, please share.

Thankfully technology marches on and once a new concept is brought to light then the world of technology becomes aware of it and it attracts those who are interested, or see a potential, begin to seek answers to improve that technology.

Piezo technology has been around a while and is well understood, both its advantages, and its limitations.

Thankfully, we still have Steven Jobs, Bill Gates and Elton Musk type individuals that are willing to take the longer view. If the short term "we have to meet the investor's quarterly profit projections" goal now driving our corporations had been historically allowed to control our global technological development then we would still be lit only by the sun and moon and traveling by foot. To paraphrase an old short quote "it was a brave man who mounted that first horse"; but, apparently he thought it was worth the risk.

And if we also did not look at every new idea critically, and evaluate the risk/reward/feasibility, we would still have hordes of people trying to turn mud into gold, or develop perpetual motion machines.

... As someone who spent more than half of my 40 years in new product development engineering, I have seen too many examples of "hell, that could never work" ideas turn into "well, damn, will you look at that" results.

I've heard that applied to some new technology as well (CDMA to be specific), but as was mentioned earlier, it didn't break the laws of physics.

 

[NTL2009]

OK, I think this thread is in need of a bit of levity.

Other than learning of the piezoelectric effect somewhere along the way in my studies, my first real awareness of them being used in a product was in the Ovation guitar ( I may have seen piezo tweeters, or piezo microphones or strain gauges, but this was at least more interesting to me, and made more of an impression). Instead of a contact microphone that was sometimes used to capture the direct vibrations of an acoustic guitar, or the electromagnetic pick-ups in an electric guitar, the Ovation guitar used piezoelectric pickups. They were mounted under the 'bridge' (where the vibrating string lengths are terminated at the body), and I think a separate one was used for each string, so the volume/tone could be balanced independently.

https://en.wikipedia.org/wiki/Pickup_(music_technology)#Piezoelectric_pickups

I also recall that unlike most electric guitars with coil pickups, the Ovation required a 9 Volt battery. The output impedance of the piezo was so high, that it couldn't drive the standard guitar amplifier properly, so the 9 V battery was used to power an FET buffer.

Hmmm, high output impedance - hard to get much useful power out of such a device. Fortunately, guitars don't need to produce a lot of power, the amplifier takes care of that. The 'power' is in your choice of chords (for you distorted guitar fans - 'never play the third!')

 

[JBA]

I am only pursuing a discussion and not a heated discourse on my part. No animosity felt or intended.

I have not said nor implied that every brain child would turnout to be the next great idea; and, every new concept will at some point have to face scrutiny, due to the scientific principal we all support (unless it is a political idea and then all bets are off).

There are dozens wild ideas generated all the time, but some of those so judged in history turned out not to be so crazy is the point I am trying to make.

I simply believe that it is really bad idea to allow the current primarily corporate view of "yes but what will it do for me today" to invade the world of scientific investigation and pursuit of new ideas.

 

[russ_watters]

...every new concept will at some point have to face scrutiny, due to the scientific principal we all support...

There are dozens wild ideas generated all the time, but some of those so judged in history turned out not to be so crazy is the point I am trying to make.

I don't agree, and others have provided examples (or pointed out that examples you provided were invalid). Indeed, you can't even get a patent on an idea that violates conservation of energy, so before anyone even knows about it, it has to have already passed scientific muster. I think you would be hard pressed to actually come up with an example of an invention that was believed to be scientifically impossible for a while before being proven valid. The closest would be a new scientific principle (like superconductivity) that was invented by scientists that brought applications with it. That cart *never* leads the horse though, though the internet is awash with crackpot perpetual motion machines that try.

I simply believe that it is really bad idea to allow the current primarily corporate view of "yes but what will it do for me today" to invade the world of scientific investigation and pursuit of new ideas.

I would agree if such an animal existed, but it doesn't in general and doesn't factor in here. @mfb brought up the amount of energy generated, but it was a side issue, after the first 10 posts pointed out the violation of conservation of energy. And his point wasn't wrong; it was another flaw in the way the project was presented. As a smilar example, a "solar" powered automatic faucet is generally a leech, but even if it is under a window, no one is going to claim you can provide grid power with it.

 

[NTL2009]

...
I have not said nor implied that every brain child would turnout to be the next great idea; and, every new concept will at some point have to face scrutiny, due to the scientific principle we all support (unless it is a political idea and then all bets are off). ...

OK, but you do seem to be treating this one as a'great idea' w/o applying what many of us consider a reasonable amount of scrutiny. I was just pointing out that seems to be a recurring theme among many, especially when it comes to anything with the 'green/renewable' label attached to it.

... There are dozens wild ideas generated all the time, but some of those so judged in history turned out not to be so crazy is the point I am trying to make. ...

I don't give much credence to the usual "people laughed at so and so" that we hear from the green 'critics of the critics' so often. First, many of those who said "it could never be done" were people w/o the knowledge to make a sound judgement. And today is different from history. Today, we have a sound understanding of the underlying principles, and at a more detailed level, computer modelling. We rarely need to build a prototype and do so much trial and error just to determine if something has a chance at success. Yes, we prototype to work out details, characterize and so forth. But, for example, that solar powered plane group didn't need to actually build a plane to realize the whole concept was very, very marginal, and a long, long ways from being able to carry a near-normal payload at near-normal airspeed. And no amount of prototyping would get them there until batteries and/or solar panels make a leap in power/weight performance.

I simply believe that it is really bad idea to allow the current primarily corporate view of "yes but what will it do for me today" to invade the world of scientific investigation and pursuit of new ideas.

As @russ_watters pointed out - is this common? And I'll make the counter-point that I believe it is a really, really bad idea to treat anything and everything with a 'green/renewable' label as something that can't be critiqued and analyzed without the critic being labeled a 'naysayer' or 'Luddite' or 'shill for the oil companies', or 'someone who doesn't care about the planet' - and I see this all the time on the comments section of green sites. I hate to even say it, but "solar roadways" anyone? Gimme a freakin' break! That is stupid on top of stupid with a side order of stupid, drenched in stupid sauce. It's a mosh-pit of stupid ideas combined, and not one of them has any merit whatsoever in a general sense, either stand-alone or combined (maybe, maybe some will work OK in some very limited niche applications). Yet, it has a cult like following. Makes me sad, depressed even.