Doubt the power of the sun?

Here are a collection of videos of concentrating sunlight to produce super high temperatures. Why has no company jumped on this? I have no idea.

"Doubt the power of the sun?"
http://www.youtube.com/watch?v=7ltqFtX7NkQ&feature=feedlik

"Melting steel with sunlight, James Mays big ideas"
http://www.youtube.com/watch?v=AJot9WKybQE&feature=related
... Melting a (I think) 4 inch hole in plate steel in about 5 seconds.

There are commercial and industrial applications of concentrating sunlight that have never been tapped before. One of these days there will be a first company who realizes this could cut their fossil fuels budget drastically and then you'll see an avalanche of businesses jumping onto the concentrating solar bandwagon.

Or it could be used for videos like this:
"1 MINUTE GRILLED CHEESE SOLAR COOKING Parabolic Mirror Star Powered Grill"
http://www.youtube.com/watch?v=aJ22QCAqFCc&feature=related

place at the focal point of reflecting mirrors?

It concentrates and stores the energy in molten salt to provide 24 hour electricity production.

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

A similar plant will be open in California by 2014 if the anti-renewable republicans don't sabotage it before then.

http://www.desertdispatch.com/news/project-11946-final-abengoa.html

http://www.solarmillennium.de/upload/Download/Technologie/eng/Andasol1-3engl.pdf

The Maricopa Solar plant in Arizona uses Stirling gensets:

http://www.srpnet.com/environment/solar/maricopasolar.aspx

It would melt lead fairly easily with solar power..

and even a mini-solar furnace kit for that lens. I got one years ago, don't know where it is now. http://www.scientificsonline.com/catalogsearch/result/?q=fresnel+solar

I think they had an even larger lens available at one point.

But in good supply since those old rear projection TVs are going out of style and being tossed by the dozens every week somewhere.

They'll melt anything. Concrete, steel, anything.

They've been using solar grills in Africa (among other places) for a REALLY long time. I've also seen pictures of pot growing operations (after they were busted) where they used mirrors or reflective metals to bathe the plants from all angles with the same grow lights. And at least according to legend (Lucian), Archimedes directed the use of parabolic mirrors to set fire to enemy sails in the Siege of Syracuse. He was certainly aware of the mathematics behind the concept but whether it actually generated enough focused heat to set the ships on fire (or if it was even attempted) will probably always be in question.

It's been a really long time since I read "Alive" (plane crash in the Andes where they had not choice but to resort to cannibalism of those who didn't survive the wreck), but it is based on a true story and I'm pretty sure it says they used some form of reflection to create a solar snow-melting device so they would have water to drink. I don't remember if they cooked the flesh that way as well, but I do remember one of the survivors saying the only part of the human body you couldn't eat was the lungs (not sure if that's TRUE or not).

The energy contained in a single charcoal briquet could easily melt steel, but they're never used for that.

Why not?

Or for our purposes, our ability to make use of concentrating light from the sun might as well be infinite.

I don't think we'll have too many factories in 100 years, if any, but till then we should be using the heat from the sun in every way possible to cut down on limited resources (especially the dangerous and expensive ones like fossil fuels).

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

This article is the English version of the French: http://fr.wikipedia.org/wiki/Four_solaire_d%27Odeillo which has better graphics and shows the heliostats reflecting sunlight to the giant mirror which then concentrates it to reach temperatures of 3500 degrees C.

If it's power you want, how about enough heat to melt any known material
==========================================

Just because you concentrate the sun's rays; you aren't getting any more energy.

You are just concentrating it.

Imagine you have a bunch of milk. Milk is essentially butterfat suspended in water.

You churn the milk to make butter - you are concentrating the butterfat.

However, do you have anymore butterfat after you churned it? NOPE
Churning doesn't "make butterfat"

Suppose you ate all that butter. How many calories did you consume?

Suppose instead of churning the milk into butter ( i.e. removing the water );
you just drank all that milk. You would get just as many calories from the
milk as you do from the butter.

By concentrating the sunlight; you can get high temperatures; but you don't
get any more "energy" or "power".

You might want to take an introductory science course. In introductory
courses, you should learn the difference between "extensive" quantities
like energy, and "intensive" quantities like temperature.

PamW

1pow·er
noun, often attributive \ˈpau̇(-ə)r\
Definition of POWER
1
a (1) : ability to act or produce an effect (2) : ability to get extra-base hits (3) : capacity for being acted upon or undergoing an effect b : legal or official authority, capacity, or right

Taking 100 mirrors and pointing each of them so their reflected light lands on one spot will definitely produce an effect.

http://www.youtube.com/watch?v=z0_nuvPKIi8

and

http://www.youtube.com/watch?v=8tt7RG3UR4c

I said concentrating sunlight results in more POWER
====================================================

You are just as WRONG about the POWER as you are about ENERGY.

Power is just the time derivative of the energy. If you are wrong about
the energy; then you are also wrong about the power.

Evidently you don't understand the basic physics that if you take those
100 mirrors and instead of concentrating their energy on one spot; you
collect the energy from each mirror individually; the sum total of the
power you get from collecting each mirror individually is the SAME
as if you concentrated the sunlight at one spot and collected the energy
there.

Again, I would recommend a remedial course in basic science in which
you learn the difference between "extensive" and "intensive" quantities.

Energy, as well as its derivative Power; are "extensive" quantities as is
the mass from my previous example with milk and butterfat that you obviously
didn't understand.

Temperature, density, and caloric density ( calaries per gram ) are "intensive"
quantities. The fact that you have high temperature doesn't mean you have
more energy.

Didn't you ever play with a magnifying glass as a kid and focused it on the
sidewalk? When you do, you get a hot spot that will light paper on fire.

However, you evidently didn't notice that the hot spot is surrounded by a
dark area. That dark area is where sun photons would have gone had not
the magnifying glass diverted them to the hot spot.

If you take the average light energy, or power falling on that dark spot and
the bright spot; you will find that the total energy is just what would have
fallen there if the magnifying glass is taken away.

Magnifying glasses and mirrors just bend light rays; they don't add energy.

You had better learn this basic tenet of elementary physics if you want to
discuss solar power intelligently.

PamW

:rofl:

Message removed by moderator. Click here to review the message board rules.

After reading my explanations of why merely concentrating
sunlight with lenses or mirrors doesn't add energy to the
process; I'll let the forum readers decide if my comments
deserved to be laughed at.

They can also decide the level of intellect used to form
the various responses posted here.

PamW

Suppose I have 1 gallon of highly toxic liquid, and I want to
dispose of it by tossing it into my local river. You say,
"Stop - you are going to pollute the river".

So I tell you that I'm going to take 999 gallons of water
and mix it with my 1 gallon of toxic liquid, so that I'll
have 1000 gallons of liquid that is 1/1000-th as toxic.

I've done the opposite of concentrating; I've diluted the
toxicity by a factor of 1000. However, I now have 1000 times
as much total liquid to toss in the river.

Do you feel better now that I've diluted the toxic crap?

You shouldn't - because when I toss 1000 gallons of stuff that
is 1/1000-th as toxic; I'm tossing the SAME amount of
toxic crap into the river as when it was all in a single one
gallon bucket.

Do you understand that dilution doesn't change the amount of
toxic crud in the river? Then you should now understand that
concentrating sunlight with lenses and mirrors doesn't increase
the amount of energy or power. At any given time of the day,
you get a certain amount of sunlight power per unit area of
collector. If you take the area of your collector mirrors or
lenses and multiply it by this power per area - you get the
total amount of power you have to work with. As above, concentrating
or diluting it is not going to increase the power above that
which you have collected.

In fact there is a reason NOT to concentrate. When I said
the amount would be the SAME, that is an idealized case with
collectors that are 100% efficient.

In reality, collectors are not 100% efficient because they
re-radiate some of the energy. This represents a LOSS; an
inefficiency to the solar system. The amount of power that
is re-radiated is given by the Stephan-Boltzmann Law and it
goes like the fourth power of the temperature.

So if you concentrate the solar energy to give you higher
temperature, you are increasing the loss / inefficiency due
to re-radiation. If you double your collector temperature, the
loss goes up by a factor of 16. If you increase the temperature
by a factor of 10, the loss rate goes up by a factor of 10,000.

One thing that gets me about so-called "environmentalists" is that
they haven't studied the Physics, but in an Aristotelian manner
think can just divine the Laws of Physics for themselves. Then
using their own made up Laws of Physics, which are wrong; they
then construct "solutions" to scientific problems, and call the
scientists and engineers dumb for not using their "solutions".

Did they ever consider that the scientists and engineers might just
be smarter than they are? Not your average self-righteous environmentalist.

I've encountered many "environmentalists" that "think" they can
boost the power of solar energy by using magnification or concentration.
Carrying their ignorant / faulty logic to its logical conclusion, we
would be able to get gigawatts of power from a postage-stamp sized
collector.

The level of scientific acuity on this board is probably the
LOWEST of all the Internet discussion boards that I
frequent.

There are some here that don't understand that the 2nd Law of
Thermodynamics demands that any heat engine must expel
waste heat.

PamW

I wouldn't like "environmentalists" either

yup

:rofl:

Did I tell you what I do for a living?

PamW

The "power" of each individual mirror has not changed.

But you can clearly see, and I even copied the dictionary definition for you so you could read it and understand, that at that spot where all 100 mirrors are pointing the power of the sun has been multiplied and instead of just making the steel plate mildly warm it melts a hole through it.

Melting a hold through something is what I call having an effect on that object.

Quote all the meaningless drivel you wish. I have clearly shown you that the power of the sun, when 100 mirrors concentrate it on one spot, is multiplied. You'll have to deal with it.

I won't be a childish imp and put a ROFL in this post because that is so juvenile. :hi:

Quote all the meaningless drivel you wish. I have clearly shown you that the power of the sun, when 100 mirrors concentrate it on one spot, is multiplied. You'll have to deal with it.
===============================================

Sorry - but you've "clearly shown" no such thing - because it is NOT TRUE

You are still confusing an "intensive" quantity temperature, with an
"extensive" property of power or energy.

Again - we have 2 solar power plants with 100 mirrors. In one power plant, we
"concentrate" all 100 mirrors on a single spot and collect the energy there.

In the other power plant, we don't concentrate the sunlight, and collect the
power from each mirror individually. Because we have 100 times the collection
area, the collectors don't get as hot.

Are you claiming that the first power plant is more powerful than the sum total
of the power collected by the second power plant; because if that is your claim -
the you are just flat out WRONG.

Evidently you are not a student of science, otherwise you wouldn't get such a
simple physics problem so wrong. You probably don't understand about the laws
of physics known as "conservation laws".

There is a law called "Conservation of Energy" - go look it up if you doubt it.
It says that you can't just make energy out of nothing.

Let's look at how this applies to one of the focusing mirrors. We have the
focusing mirror, and we have an incoming beam of sunlight which is not concentrated.
It hits the mirror, and leaving it we have a beam of sunlight which will be
concentrated when it hits the collector.

Let's say the power in the incoming beam is "P" kilowatts. Now if you claim that
the power of the concentrated beam is going to be 100 P kilowatts when it is collected,
then it has to have a power of 100 P kilowatts when it leaves the mirror. No energy
is going to be added by traversing the space between the mirror and collector.

So you have a mirror that has 1 P kilowatts coming in, and 100 P kilowatts in a beam
leaving. In other words, we have increased the power of the beam by 99 P kilowatts by
just having the beam reflect from a mirror.

In 1 second, the amount of energy coming in is the power P times 1 sec = P kilo-Joules,
and leaving we have power 100 P times 1 sec = 100 P kilo-Joules.

So every second, the system would create 99 kilo-Joules out of NOTHING.

Can you not see that this is a VIOLATION of the Law of Conservation
of Energy? Every second, according to your description, you are creating energy
out of nothing.

Sorry, but the Universe doesn't work that way.

If it did, why stop with just one mirror. Take the output beam with more power and
reflect it off another mirror and get 100 x 100 P = 10,000 P; i.e. ten-thousand times
the initial power. If you add a reflection by a third mirror; then the power will have
increased by a factor of 1 Million. Just keep going...

Do you not have the intellect to see that this can't be? Energy for nothing?

Sorry; but it is YOU that is just plain 100% WRONG about this.

If you doubt it; take the posts of this thread to your local high school and find
the physics teacher and ask him or her which of us is correct.

When you find out the answer; you should take the opportunity to sign up for some
remedial courses in science.

PamW

If anything is gobbledygook, it's your definitions of power from the dictionary. Do you take a lexicon of sports terminology when you want to have a medical discussion with your physician?

We're talking about a scientific issue, and the wordy, imprecise, non-technical definitions you give above are not what is really needed. We need the well-defined, precise, technical definition of power that I gave which is the temporal derivative of work or energy:

http://physics.about.com/od/glossary/g/power.htm

Definition: Power is the time rate at which work is done or energy is transferred. In calculus terms, power is the derivative of work with respect to time.


Suppose we have an engine, and the work output of the engine as a function of time is given by:

Work = a exp(bt) where "a" and "b" are constants and "t" is time. How does your definitions of power above tell us anything about what the power of the engine is as a function of time? However, my definition tells us exactly how to determine the power.

Evidently, you don't realize that your wikipedia definition above that mirrors amplify power is just plain wrong.

You evidently haven't taken my challenge to take this to your local high school physics teacher so that he or she can dispel your misunderstandings and misconception of the laws of Physics.

Again, mirrors don't increase either the total amount of energy nor power; they merely concentrate the energy in a smaller location.

Mirrors and lenses only alter the direction of the light; they don't create energy.

As for not having the time; how long does it take you to make such a decision if you are fluent in the field of knowledge. It didn't take me but a fraction of a second of reading your posts to decide that you are not learned in the field of physics nor science.

PamW

I wish I could get the time back that I've wasted reading your post.

Again, let us take the example of the engine whose work output is exponentially increasing:

Work = a exp(bt) where "a" and "b" are constants and "t" is time.

How does your definition above, without any other assumptions or definitions; tell us what
the power is for the above engine?

In any case, the definition of power is really secondary to the discussion, since even
your statement above means that power and work / energy are linked, so if one makes
an error in work / energy as you did when you made a claim that mirrors increase power,
and hence energy in violation of the physical law of Conservation of Energy.

It's confounding to a physicist that anyone would believe something that the
fundamental laws of Physics say is impossible.

You are just concentrating the sunlight onto a smaller area with your curved mirrors.

Mirrors don't make energy, and hence don't make power; so the amount of power is unaffected
by the mirror. You just get more concentrated power in a smaller region; but you don't get
more total power or energy.

However, you are a splendid example of how environmentalists "think";
and while Mother Nature will see to it that your energy production methods will all
come to naught.

PamW

With all the yammering and bickering over a single word or term. It's no wonder science hasn't progressed on cures for diseases, working nanotechnology, Artificial Intelligence, etc. All the physicists are arguing about what the meaning of "is" is. When done with that they'll argue about what is or is not power.

"The capacity to learn is a gift;
The ability to learn is a skill;
The WILLINGNESS to learn is a choice." -Unknown

The two are not even close to being the same thing. They do not even overlap.

I suspect a doppelganger is in our midst.

Pam used to be knowledgeable and wise, pro-nuclear but not anti-renewables. And she was always respectful of others. I miss her.

I need over a hundred thousand square miles of land and I need both environmentalists and venture capitalists to get out of my way. No questions. Period. End of discussions.

Why hasn't it been done? Because 1) no one owns the land necessary to do it 2) no one has the environmental go ahead to do it (using BLM leases), 3) because the startup costs are higher than current energy investments, but you can't even try without getting past the first 2.

Glad you aren't using computers.
lol.

During the day the salt would store enough energy to power night time. It's not a particularly difficult problem.

...about a go-anywhere pumped hydro design. Preferable, imho...

and a place to store it in the second place.

I think a similar effect could be created by having two shafts, two metal clad tubes filled with rocks but connect them with a cable or chain which turns large gear which turns small gear connected to a generator. No water, no piston rings to worry about. Any thoughts?

During the day the salt would store enough energy to power night time. It's not a particularly difficult problem.
========================

A typical solar plant operates on a 25% duty cycle; that is the bulk of its energy it gets during
a time period from 3 hours before local noon to 3 hours after local noon; i.e. the bulk of its
energy is derived in a 6 hour time period. However, we demand power 24 hours a day; so a solar
plant may have to store up to 75% of its daily output.

Consider a typical 1 Gw(e) power plant conventional power plant, and what it would take to supplant
this power plant with a solar installation. In 24 hours, the 1 Gwe plant will, by definition, output
1 Gw-Day of electric energy. From above, a solar plant that supplants it may have to store as much
as 0.75 Gw-Days of energy. However, if you are storing energy as heat, as is the case with molten
salt; then you have to take into account the efficiency by which this heat can be converted to
electric energy. If you want to store enough heat to give you 0.75 Gw-Days of electricity, then at
a typical 40% conversion rate for a Rankine cycle; you need to store 1.875 Gw-Days of heat energy.

Since the Gw-Day is just a unit of energy; we can convert it to any other unit of energy so that
meaningful comparisons can be made. Heat of 1.875 Gw-Days is the equivalent of 38.6 kilotons or
equivalent of 2.5 Hiroshima atomic bombs.

To replace a single 1 Gw(e) power plant; you need a molten salt storage capacity that can store
2.5 Hiroshima atomic bombs worth of heat energy. You need one of these for EACH conventional
power plant you wish to replace.

Conceptually easy; but think about what happens if there is an accident and 2.5 Hiroshima bombs
worth of heat are let loose. The Little Boy bomb deposited only 1 of these Hiroshima units worth
of heat into the atmosphere above Hiroshima; and look what happened.

PamW

...such as in a massive accident (a plane flies into it or a terrorist gets a bomb into the inner chamber because they somehow breached security), what happens to the salt, PamW? 1) it's close to ambient pressure 2) it falls into a cooling chamber and is not released spontaneously.

We're talking hundreds of thousands of gallons of molten salts.

There's a massive difference between releasing a lot of energy in a small localized point in one spontaneous moment, and having a lot of energy over a relatively large area (say, the size of one of those big oil storage containers), which will release slowly over time as it gets cooled and pumped into a second container holding the cooled, though not solidified salts).

Yes, you would need to have 2-3 times as many mirrors to produce 24x7 electricity, but it's not really that big of a deal, you should never calculate the energy use of a renewable plant based on the peak capacity of said plant, you always base it on the potential capacity factor that plant can produce. Every single renewable design plan does it this way (regardless of what others might say, the contracts use CF and not Peak Capacity). The whole "this plant is capable of X capacity" thing is going away as far as I can tell, as renewable energy companies are learning that it's bad PR when they report peak capacity and then people start pitching a fit. I've been seeing much more accurate energy production numbers coming from the renewable community the past few years, it's really helping shut the naysayers up.

You could also use flywheels or other kinds of batteries at various storage locations nearer to the source where people will use your energy, you could also use hydrogen production and the like for fuel cells. I say molten salts because they're relatively easy to get to work.

The best nuclear designs use molten salts and when their energy is "released"...
==================================================

Do you know how many nuclear reactors used molten salts? EXACTLY ONE!

The Oak Ridge National Laboratory had a short-lived experiment called the
Molten Salt Reactor Experiment or MSRE. That is the ONLY reactor
built to use molten salts, and Oak Ridge discontinued the experiment and did
not pursue that line of reactor design further.

PamW

Reading comprehension fail?

I do not like Gen III+ or older technology because pressurized water containment is outdated and archaic technology.

Yes, you would need to have 2-3 times as many mirrors to produce 24x7 electricity, but it's not really that big of a deal, you should never calculate the energy use of a renewable plant based on the peak capacity of said plant, you always base it on the potential capacity factor that plant can produce. Every single renewable design plan does it this way (regardless of what others might say, the contracts use CF and not Peak Capacity).
======================================

Sorry - the contracts and ratings are always "peak" power. When you buy a 2 kW solar array, that 2 kW is
the peak capacity of the array.

When Siemens touts their 2.5 Mw wind turbines; that 2.5 Mw is the peak power; and not the average.

You see it doesn't make sense to rate a solar array or wind turbine in terms of average power; because
the average power that the array or turbine will produce is site dependent.

You are just plain flat out WRONG to say that every renewable plant is rated by average power with
a capacity factor applied. NOPE - they are rated at peak power and the capacity factor is what it
is for a particular site.

As far as shutting up naysayers; does that include the National Academy of Science and Engineering, who
have said in a number of reports that the maximum percentage that we can count on renewables delivering
is about 20% of our electric power demand. That's fine with me. We should exploit renewables for all the
electric power they can deliver; which is about 20% of our total. But what do we use for the other 80%?

PamW

What the poster is saying is that the utility does not pay the owner of the wind farm for its "rated capacity" aka Peak Capacity (which for wind is derived by a ridiculous formula).

Utilities pay the owner of a wind farm based on actual power output to the grid, in kWh, multiplied by the spot market price for electricity at that time. When demand is low and generation is high that price can go as low as 1 cent per kWh or it can even go to zero.

This is why I always say that wind farms need to be able to store their electrical output for when it's needed (wind being strongest usually at night when demand is lowest).

So the energy procurement contract will have the CF in there in fine print because 1) the wind farm doesn't want to be held liable for not being able to meet the energy requirements and 2) the power plant doesn't want to plug into a system that isn't contractually sound.

For wind it's something like 20% CF even though the wind plant may actually provide as much as 40% CF. It's a baseline so that providers aren't screwed. And it's not based in any way on peak capacity.

Stop putting words in my mouth. I was contrasting between public relations numbers and actual contract numbers.

It remains a fact that the energy procurement contract always gives an average capacity factor. It's not made public in the past because often times that is 2-3 times less than what the power option provides. The lawsuits would be enormous if a renewable plant said "we can provide 1MW of power" (the peak capacity of their plant) when it's 1/3rd of that or less. However, that is changing, despite what posters here would like. (Some pro-renewable people might hate that some plants get a lower rating, while anti-renewable posters would hate more accurate numbers because then they can't use them to bash the plant.)

http://bravenewclimate.com/2011/11/13/energy-storage-dt/#comment-142242

Nuclear advocates would be wise to stop this false equivalence because as more and more plants start to adopt capacity factor as their load ability, this argument about capacity factor will become moot.

You could also use flywheels or other kinds of batteries at various storage locations nearer to the source where people will use your energy, you could also use hydrogen production and the like for fuel cells.
================================

We've discussed flywheels here before too. At least with the flywheels, you don't need the extra
storage capacity due to the 40% conversion efficiency that you need when heat is the storage medium.

However, one fellow poster suggested storing that 15 kilotons of needed storage capacity with flywheels.
Again, as with your opening example, when the airliner hits the building full of flywheels and those
flywheels fail and release their energy as heat; that 15 kilotons of heat energy doesn't just disappear.
The law of conservation of energy doesn't allow it to just go away.

So 15 kilotons of heat gets deposited in the atmosphere at ground level where the building once stood.

PamW

All flywheels are buried for that reason.

In any event, you're not storing 15kt in one flywheel, that's dozens if not hundreds of flywheels.

And a flywheel's energy can be very quickly discharged, so if you had an accident or an attack, the flywheels not immediately effected could be safe'd in short order.

http://www.youtube.com/watch?v=-hu4nrcXxm8

http://www.solarreserve.com/

You need tens of thousands of these little guys though, going across vast swaths of desert.

The environmental impact would be enormous (likely cooling the desert, screwing up the local ecosystem, etc).

But it could be done.

I never under estimate the power of the Sun.