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?