[math-fun] one crazy idea
Hello, I was thinking at how we could procuce energy in a simple way, like having solar ovens with mirrors and such devices. This lead me to Archimedes and the way he used to 'toast' roman warships from the Syracuse citadel, apparently that idea was somewhat validated once, they found a way to toast a pile of plywood resembling a roman ship with plates of metals used at the time. Anyhow which lead me to think : what about today ?, suppose we would hypothetically having the same kind of threat but from space : an alien warship threatening to zap humans from existence. What about doing the same thing ? Billion of people using mirrors directly aimed at (more or less precisely) at this alien ship : what would happen ? More precisely, what would be the effect in energy having let's say 100 miilion mirrors aimed at one point in space toward one of those things, would it do the same thing ? Is this feasible, we would have one shot at it. This may sound naive, well is it ? Can someone calculate what output of energy this represent ? Best regards, Simon PLOUFFFE
You may find this interesting (and tangentially related in terms of energy output): http://what-if.xkcd.com/13/ Charles Greathouse Analyst/Programmer Case Western Reserve University On Wed, Jul 17, 2013 at 5:07 AM, Simon Plouffe <simon.plouffe@gmail.com>wrote:
Hello,
I was thinking at how we could procuce energy in a simple way, like having solar ovens with mirrors and such devices. This lead me to Archimedes and the way he used to 'toast' roman warships from the Syracuse citadel, apparently that idea was somewhat validated once, they found a way to toast a pile of plywood resembling a roman ship with plates of metals used at the time.
Anyhow which lead me to think : what about today ?, suppose we would hypothetically having the same kind of threat but from space : an alien warship threatening to zap humans from existence.
What about doing the same thing ? Billion of people using mirrors directly aimed at (more or less precisely) at this alien ship : what would happen ?
More precisely, what would be the effect in energy having let's say 100 miilion mirrors aimed at one point in space toward one of those things, would it do the same thing ? Is this feasible, we would have one shot at it.
This may sound naive, well is it ?
Can someone calculate what output of energy this represent ?
Best regards, Simon PLOUFFFE _______________________________________________ math-fun mailing list math-fun@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun
On 7/17/2013 2:07 AM, Simon Plouffe wrote:
Hello,
I was thinking at how we could procuce energy in a simple way, like having solar ovens with mirrors and such devices. This lead me to Archimedes and the way he used to 'toast' roman warships from the Syracuse citadel, apparently that idea was somewhat validated once, they found a way to toast a pile of plywood resembling a roman ship with plates of metals used at the time.
Mythbusters (the TV show) tried this a couple of different times, even using modern mirrors. It never really worked.
Anyhow which lead me to think : what about today ?, suppose we would hypothetically having the same kind of threat but from space : an alien warship threatening to zap humans from existence.
What about doing the same thing ? Billion of people using mirrors directly aimed at (more or less precisely) at this alien ship : what would happen ?
Solar illumination at the surface of the Earth is about 1kw/m^2. So if each person wielded a one square meter mirror and they all successfully aimed them at the same point you could, at best get a billion kw/m^2 on the target point - which if it weren't very shiny would probably burn a hole in it. But the problem, which Mythbusters had, is holding the mirrors still and pointed at the same spot. At high intensities you also get heating of the air and defocusing due to different densities. Of course all these problems can be greatly mitigated with adaptive optics; which have been developed for laser weapons. http://news.yahoo.com/navys-laser-weapon-blasts-bad-215808231.html Brent
More precisely, what would be the effect in energy having let's say 100 miilion mirrors aimed at one point in space toward one of those things, would it do the same thing ? Is this feasible, we would have one shot at it.
This may sound naive, well is it ?
Can someone calculate what output of energy this represent ?
Best regards, Simon PLOUFFFE _______________________________________________ math-fun mailing list math-fun@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun
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It is a mistake, I typed toooo fffast. Seriously, Every time there is a neat idea about energy, there is always something that makes it that : it finaly does not work so well. For example, Geothermic energy, in theory the potential is quite big, but in practice, well nobody want's to invest in a slow process or somehing that does not use petroleum, where profits are much more interesting. Wind energy, Alexander Graham Bell found a way with kites to gather energy, you just have to construct a kite in a tetrahedric shape and with a cable, it flies by itself, this was done 100 years ago, and then : well it does not work so well., .. etc. A counter example : The ITER project in France, well that one cost a lot and still does not work even in prototype mode BUT it uses a lot of high tech devices and technology and it is probably why governments are paying a lot for it : well, look where the money goes and you will perhaps understand the forces in place (nothing to do with atoms and lasers). just $$$. Another example : simple mirrors, why can't we buy , find a simple device to produce 2000 watts when there is a lot of sun for cheap ??, This does WORK, in africa they have a lot of those sun-ovens, it uses the sun to cook something : so there is a way to get 1000-2000 watts with a device that cost 100 $, what is the problem, can't we just multiply to get 1 gigawatt ? This is cheap to produce yes but perhaps the economic model is not : meaning that if you can buy a simple device to get 3000 watts out of the sun for not much, where are they going to put taxes and profits in this ?? if there is nothing to push , maintain or a 3 way profit or taxe scheme out of it : well they will find good reasons to say that : it does not work. 3 way model : the car : you buy a car : there is gas to put in it (lots of taxes too), + the maintenance is costly, this is the 3 way model. Another example : why can't we convert plastics into petroleum ? and this works, a certain woman (A chemist) found a catalytic product to make petroleum using any plastic. well... you know, it does not really work... etc etc. There is a film about this , she is from India. And this is where (we ) the mathematicians we should first calculate the cost and the feasibility of something like that and prove that : this DOES work in term of physics and output of energy. Do we have to do it ourselves ? Best regards, Simon Plouff (f optional) e.
On 7/18/2013 7:22 AM, Simon Plouffe wrote:
Another example : simple mirrors, why can't we buy , find a simple device to produce 2000 watts when there is a lot of sun for cheap ??, This does WORK, in africa they have a lot of those sun-ovens, it uses the sun to cook something : so there is a way to get 1000-2000 watts with a device that cost 100 $, what is the problem, can't we just multiply to get 1 gigawatt ?
You're ignoring the entropy. A watt of electrical power is very low entropy and hence much more useful and valuable than a watt of heat at 100C. That's why it's cheap and easy to get heat from sunlight, but hard to get electricity. Brent Meeker
Somewhere in a desert near L.A., there's a field of mirrors controlled by little pre-Arduino sun-tracking computers that aim the sun at a tower in the middle. The idea is to create steam in the tower. I assume that because there hasn't been much press, this idea isn't working out as well as the promoter had expected. Among other problems, transmission losses from the desert to L.A. will eat up perhaps 50% of the electrical energy. At 12:14 PM 7/17/2013, meekerdb wrote: Mythbusters (the TV show) tried this a couple of different times, even using modern mirrors. It never really worked.
50% loss for that distance seems high. "Transmitting electricity at high voltage reduces the fraction of energy lost to resistance, which varies depending on the specific conductors, the current flowing (measured in kilo-Amperes (kA.)) and the length of the transmission line. For example, a 100 mile 765 kV line carrying 1000 MW of energy can have losses of 1.1% to 0.5%. A 345 kV line carrying the same load across the same distance has losses of 4.2%.[8]" [Wiki, but it does sound plausible] Other sources say that California gets some of its electricity from as far away as Alberta and Texas. -----Original Message----- From: math-fun-bounces@mailman.xmission.com [mailto:math-fun-bounces@mailman.xmission.com] On Behalf Of Henry Baker Sent: Thursday, July 18, 2013 7:36 AM To: math-fun Subject: [EXTERNAL] Re: [math-fun] one crazy idea Somewhere in a desert near L.A., there's a field of mirrors controlled by little pre-Arduino sun-tracking computers that aim the sun at a tower in the middle. The idea is to create steam in the tower. I assume that because there hasn't been much press, this idea isn't working out as well as the promoter had expected. Among other problems, transmission losses from the desert to L.A. will eat up perhaps 50% of the electrical energy. At 12:14 PM 7/17/2013, meekerdb wrote: Mythbusters (the TV show) tried this a couple of different times, even using modern mirrors. It never really worked. _______________________________________________ math-fun mailing list math-fun@mailman.xmission.com<mailto:math-fun@mailman.xmission.com> http://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun
On 7/18/2013 6:36 AM, Henry Baker wrote:
Somewhere in a desert near L.A., there's a field of mirrors controlled by little pre-Arduino sun-tracking computers that aim the sun at a tower in the middle.
The idea is to create steam in the tower.
I assume that because there hasn't been much press, this idea isn't working out as well as the promoter had expected.
It's near Lancaster and I think it's working just fine. It's the only one in the U.S. but there are several others in the world: http://en.wikipedia.org/wiki/List_of_solar_thermal_power_stations Apparently the parabolic trough design seems preferred.
Among other problems, transmission losses from the desert to L.A. will eat up perhaps 50% of the electrical energy.
That's a huge over estimate of the loss. Average loss rate is about 7%, but only a small part of that is the loss due to the long, high voltage lines. Measured transmission line losses are 2% to 3% per 1000Km. http://large.stanford.edu/courses/2010/ph240/harting1/ Brent
On Jul 18, 2013, at 1:41 PM, meekerdb wrote:
On 7/18/2013 6:36 AM, Henry Baker wrote:
Somewhere in a desert near L.A., there's a field of mirrors controlled by little pre-Arduino sun-tracking computers that aim the sun at a tower in the middle.
The idea is to create steam in the tower.
I assume that because there hasn't been much press, this idea isn't working out as well as the promoter had expected.
It's near Lancaster and I think it's working just fine. It's the only one in the U.S. but there are several others in the world:
http://en.wikipedia.org/wiki/List_of_solar_thermal_power_stations
This can't be right. There is definitely one on Kirkland AFB in Albequerque, near the Atomic Bomb Museum (highly recommended!). I think that one is a prototype, and has been there for at least 7 years. The Wikipedia article presumably is only counting production versions.
Among other problems, transmission losses from the desert to L.A. will eat up perhaps 50% of the electrical energy.
That's a huge over estimate of the loss. Average loss rate is about 7%, but only a small part of that is the loss due to the long, high voltage lines. Measured transmission line losses are 2% to 3% per 1000Km.
http://large.stanford.edu/courses/2010/ph240/harting1/
Brent
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We need to compare apples with apples. If I have a solar panel on my roof, I don't have to pay for power transmission from a desert hundreds/thousands of miles away to my refrigerator. (I also don't have to pay for all those ads on TV or those utility lobbyists.) The utilities love to tell you how efficient their transmission lines are, but neglect to tell you about the _net_ loss for the entire system, including delivery to your refrigerator. (We're not even counting the $$ costs of building & maintaining these transmission lines, the cost in forest fires (many large California fires have been sparked by transmission lines), or the cost to the environment -- including visual pollution -- of these transmission lines.) At 10:41 AM 7/18/2013, meekerdb wrote:
Among other problems, transmission losses from the desert to L.A. will eat up perhaps 50% of the electrical energy.
That's a huge over estimate of the loss. Average loss rate is about 7%, but only a small part of that is the loss due to the long, high voltage lines. Measured transmission line losses are 2% to 3% per 1000Km.
participants (8)
-
Charles Greathouse -
Cordwell, William R -
Dan Asimov -
Henry Baker -
Marc LeBrun -
meekerdb -
Simon Plouffe -
Tom Knight