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Re: [Phys-L] [Phys-l] real-world exercise : AB 306



Well …. It’s happening.

http://asmdc.org/members/a43/news-room/press-releases/california-roads-to-become-a-source-of-energy

My source:

http://prorevnews.blogspot.com/2016/08/how-freeways-can-provide-electrical.html?utm_source=feedburner&utm_medium=email&utm_campaign=Feed%3A+prorevfeed+%28UNDERNEWS%29


I also think it’s a matter of robbing Peter to pay Paul.


bc thinks by the time the extraction of energy from us Calirornians to pay the infra structure, there won’t be any ‘biles and roadways.

1, As JD wrote, stiffening is more efficient and cheaper. Road will last longer, also!
2, Concomitantly, less gasoline, less CO2. Obtain useable energy by the least CO2 producer, not gasoline.

On 2011, Mar 02, , at 16:46, John Denker <jsd@av8n.com> wrote:

Hi Folks --

On 02/27/2011 11:54 AM, I wrote:

Note that there are two topics on the table here:
1) The physical principles.
2) The broader notion of how to handle open-ended questions.

Let me talk a little more about item (2). In this context, it
can be formulated as a _scenario planning_ exercise. The first
rule of scenario planning is to consider _all_ of the plausible
scenarios.
++ Scenario planning is heavily used in the business community.
In this context it is sometimes called a _business case_ analysis
or a case-by-case analysis.
++ Scenario planning is also heavily used in science, including
scientific research. In this context a scenario is often called
a hypothesis. The rule remains: consider _all_ of the plausible
hypotheses. Consider _all_ the plausible scenarios.

This is something that everybody is *supposed* to learn in school.
It is supposed to be introduced in third grade and reinforced
repeatedly thereafter. Unfortunately, it is often taught wrong,
quite grotesquely wrong, more often than not. This needs to be
fixed. We should not wait until people are in MBA school or in
some upper-division physics course before they learn to consider
_all_ the plausible scenarios.

The infamous "Scientific Method" poster
http://www.av8n.com/physics/scientific-methods.htm#sec-poster
speaks of "the" hypothesis (singular). All too often, people
pick one hypothesis -- before they have any real evidence -- and
consider that to the exclusion of all others. This is a travesty.
It defies common sense.

Let's take piezoelectric roads as an example, and work out the
business case.

-- Plan A is to install piezoelectric transducers in the roads.
This captures energy that otherwise would go to waste. To
understand this in more detail, we invoke some fundamental
physics, namely the idea that energy cannot be created from
scratch. This is another idea that is supposed to be introduced
in third grade. The relevant equation is
energy taken from car = energy captured by piezo
+ energy wasted

-- Plan B is to leave the roads as they are.

The folks who are touting Plan A like to compare it to Plan B.
The claim is that under Plan A, there will be less wasted energy,
because the road is effectively stiffer.

That's fine as far as it goes, but we must also consider Plan C.
Remember the rule: Consider _all_ of the plausible scenarios.

-- Plan C is to stiffen the roadway /without/ adding piezos.

Now at this point, it should be obvious that Plan C is Pareto
superior to Plan A. That is, Plan C is in some ways better and
in no ways worse. Plan C can be done for a fraction of the cost.
It is at least as effective as Plan A in reducing the waste of
energy. Actually it is strictly /more/ effective, because the
piezos and the associated circuitry are not 100% efficient.
Under Plan C, energy that would have been wasted is returned
directly to the vehicles.

If you analyze Plan C, you will discover it is worthless, because
the amount of energy involved is very very small. Even if you
don't analyze Plan C in any detail, you know that Plan A will
never be worth doing, because it will always be worse than Plan C.

I'm leaving out a bunch of details, such as the dollar value of
various forms of energy, but this doesn't change the conclusions.
Feel free to re-do the analysis yourself, including these details.

It is typical of real-world problems that you cannot solve them
using one idea alone. You need to string together several ideas,
such as "conservation of energy" and "consideration of _all_ the
plausible scenarios".

Sometimes for pedagogical reasons we break things down so we
can introduce the ideas one by one. That's fine as a starting
point, but we must not allow it to be the ending point!

There is a disease called "equation hunting" whereby students
run down a list of equations to find "the" equation that applies.
This method sometimes works for end-of-chapter problems that have
been cooked to /make/ them yield to this method ... but it doesn't
work for real-world problems. Equation hunting is a disease that
needs to be stamped out.

James Dann wrote:

I think it's a good idea and worth checking out. I have a few in my
lab and they are neat devices. We squeeze a lot of things in this
world -why not capture some of this 'wasted energy'

I'm all in favor of checking things out. In this case, the checking
is very simple. As soon as we consider Plan C, we know that Plan A
is *not* a good idea, and no further checking is necessary.

This is a great student project by the way.

Not really.

We need to arrange things so that every student -- and every alumnus --
is able to analyze a proposal such as this. That includes analyzing it
instantly and correctly. This shouldn't be considered a project; it
should be a simple homework assignment.

There is hope: Here are a couple of people who figured it out a year
and a half ago, labeling innowattech as an "obvious scam":
http://www.alternative-energy-news.info/produce-electricity-while-you-drive/

And here is a good article about a similar scam from mid-2007:
http://www.theregister.co.uk/2007/07/30/all_the_power_they_would_ever_need/

===============

Action item: If you have one of those infamous "Scientific Method" posters
that talks about "the" hypothesis (singular), rip it down and throw it away.
Replace it with something that says
_Consider /all/ of the plausible scenarios._
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