Step 1: Install solar power plant on a hill near a city. This plant should be the solar collector type, but with solar reflectors aimed at the city, rather than the sun.

Step 2: Give everyone in this city a lump of a material that hardens. Could be as cheap as clay. Include instructions on how to stick a piece of this lump to their roof together with a CD aimed to reflect light at the hill (doesn't matter what time this is done - on average many CD's will be aimed at the hill).

Soon you'll have a shining silver city with abundant power.

(thanks, [Rayford] for inspiration)
-- Worldgineer, Jan 22 2004

Helios helper http://www.halfbake...dea/Helios_20helper
Similar idea to power the world with AOL CD's. Looks the same to me. [Laughs Last, Oct 04 2004, last modified Oct 05 2004]

MSCAoD http://www.halfbake...rray_20(of_20Doom!)
The next level [Worldgineer, Oct 04 2004, last modified Oct 05 2004]

A forum post http://www.ecolivin...le/messages/57.html
Someone has tried this in New Mexico [ooys, Oct 04 2004, last modified Oct 05 2004]

Physics Problem http://zebu.uoregon...strok/sunstrok.html
Solar reflector physics problem, with formulae. [sehrgut, Oct 25 2005]

Helios Helper Helios_20helper
Helios Helper: a home solar concentrator using AOL CDS. [sehrgut, Oct 25 2005]

I note that AOL's latest ads spoof themselves, with people making artwork out of AOL CDs, etc.
-- DrCurry, Jan 22 2004


I like the idea. I saw a guy make a Tesla turbine using about a dozen of them. I tried it and it worked. Maybe there's something there :) Maybe I'll try a hot water heater out of them. There are also lots of other sources for free cd's. I know my father in law gets about 20 a year from GM Parts updates. Good luck!
-- clafever, Jan 22 2004


Would you not need to steer the CDs to account for the moving sun?
-- kropotkin, Jan 22 2004


Every hour or so you have to go up on the roof and readjust your CD.
-- AO, Jan 22 2004


[krop] That would be ideal, and much more efficient. But it would require little motors and a few other components that are more expensive than clay. With this idea we fight inefficiency with a very large supply of material.
-- Worldgineer, Jan 22 2004


Just have each city block set thier cds up at diffrent defined times. That way the concept stays cheap but there are always some cds hitting their mark.
-- sub_text, Jan 22 2004


Yes, and housing near the plant have low rent and come with sunglasses.
-- Worldgineer, Jan 22 2004


Wow. That would hurt your eyes.
-- spacecadet, Jan 22 2004


Since AOL has strategically flooded every home with more then one of their precious CDs, everyone could place roughly 12 CDs each perfectly calibrated for a different hour of the day. Thus, eliminating the need for adjustment.
-- BigGibbyG, Jan 22 2004


Sorry to go on and on but it's fun. Just trying to contribute. to the meham. I'm sure some of yo uhave tried this but here goes.

If you put two of them back to back and use a 5" diameter 1/8" cross section oring between them then put a bolt or whatever in the middle pulling the two centers together you would have a quasi spherical surface. More conic than anything. Try this sometime. You'll be amazed at the heat you can get.

I know of coarse this would require near perfect tracking because you would have a smaller beam but hey if a bug flew in front of it near its focal point... well...zap...smoke...poof : )

I made a whole bunch of these using about 100 surplus lids from containers that were about 4" in diam. and 1/2 inch deep. Just drilled a hole in the center, set the cd on the open end, put a bolt and fender washer through the cd then the lid and a nut on the back. Adjustable focus too. Not a mirror of coarse, I'm an astronomy equipment manufacturer. I put a bunch of these on a board all focused within about a 4-5 inch area and fried my fence rather quickly. Have fun.

Now I know what we can do with all of the out of date satallite dishes in mobil home parks and out on farms. No insults intended. Just glue cd's to them and poof there's your sterling engine reflector.

Also surplus perfectly mirrored hard drive discs work great too.
-- clafever, Jan 22 2004


[claf] Thanks for the input, but it looks like your comment would be much more helpful in [Laugh]'s link. Having any kind of curve in the MACSCA implementation would not do at all - you'd disperse the light far before it reaches the power plant.

It is nice to know that CDs reflect infrared light well (//You'll be amazed at the heat you can get.//), as I was hopeful but not sure CDs are as reflective in that specrum as they are in the visible spectrum.
-- Worldgineer, Jan 23 2004


I'm happy just sticking with coasters... but my cups do that for me :(
-- Ossalisc, Jan 23 2004


You could maybe arrange the mirror CDs so that for most of the day they point in different directions, then at a particular time of day (maybe only one day a year) they all focus at a particular point. Like Stonehenge, except using CDs instead of megaliths. And with focussing.
-- kropotkin, Jan 23 2004


I think the issue with doing this on earth would be the distance spread vs. atmospheric losses in the power transmission, limiting the total output. The amount of land area needed to have a few CD's on everyone's roof is likely to be too large a distance in the outlier houses for there to be any more gain.

Interesting about AOL CD's and IR rays. Makes me want to revisit my AOL roofing shingle idea. Might have a melt problem, though.

I love the irony of using Stonehenge as the ultimate earth-based alien ship destructo-laser. We and our ancestors will have come full-circle.
-- RayfordSteele, Jan 23 2004


For some inexplicable reason this idea is doing much better in the voting department than my own.
Things that make you go Mmmmhhh.
-- 2 fries shy of a happy meal, Jan 24 2004


Yours was different. This idea's doing much better than my Rainforest Fruit, if that helps you feel better.
-- Worldgineer, Jan 24 2004


It takes some of the edge off. (+) btw
-- 2 fries shy of a happy meal, Jan 24 2004


(sorry for churning, but I realized I've never linked to the MSCAoD (link))
-- Worldgineer, Aug 18 2004


Don't apologize for a churn - there's a lot of good ideas some folks've never seen, and this brings 'em up faster.
-- shapu, Aug 18 2004


I seem to remember an Asimov's novel where a pack of soccer fans fry the referee using a lot of silvered booklets covers (not CD's of coarse).
-- finflazo, Aug 18 2004


- you mean the short story "Case of sunstroke" by Arthur C Clarke.
-- hippo, Aug 18 2004


You are Korrect. Thanks, Hippo.
-- finflazo, Aug 19 2004


Baked to some extent, or it sounds like it, but I can't find any more than the reference in a forum to my [link].
-- ooys, Aug 19 2004


[fin] That's wonderfully evil. See my MSCAoD idea (link) for an even closer comparison.

[oo] Cool, I hope Ray continued his/er project.
-- Worldgineer, Aug 20 2004


We have this gigantic field of mirrors at the Almeria desert powering an experimental smelting facility, and when at standby they focus on the air in front of the tower, and the air just....burns, that's the word for it. I imagine it's the dust in suspension getting hyper-hot. But you see this x-tremly bright point hanging in there and it takes a little to realize what it is.
-- finflazo, Aug 20 2004


I tried this on a backyard scale... cds aren't anywhere near as reflective as mirrors, you're losing a lot of efficiency. Of course if the scale is large enough it doesn't matter as the cds are free +
-- eulachon, Aug 20 2004


I drew a neat design for a table lamp with a central column of stacked CDs, and a T5 fl. tube through the center hole. I like this solar concentrator idea better.
-- elhigh, Jun 17 2005


[elhigh] Your lamp intrigues me. T-5's are considered too bright for direct illumination, and CDs might spread out the light and therefore the intensity. Of course, the shape of the CD may act as a lens and, well, blind you.
-- Worldgineer, Jun 17 2005


[World], the focal length of any optic effect the CD might have would be measured in millimeters, and not many of them. The light from the tube shouldn't be too bad. BTW, the base of this thing would weigh several kilos; that much solid plastic for the base gets pretty heavy.
-- elhigh, Jun 17 2005


[BigGibbyG], your idea is getting closer to what is necessary, but the main problem with this idea is that each household is contributing, at any given moment, the energy collected by a single CD, 120mm diameter (here discounting the center and rim of the CD, which are non-reflective), giving a reflective area of about 0.0113 m^2. This results (see "Physics Problem" link) in 11 watts of power being reflected from each CD. So, assuming an impossible, 100%-efficient solar plant, each citizen is contributing 11W of electricity. Which means, of course, that each citizen can run a small fluorescent bulb (provided they don't try to turn them on at the same time).

For this to work, each citizen would have to have nine reflectors trained on the station for each 100 watts of power they use, at any given moment. Also, even those closest to the station would need on the order of one reflector per ten or fifteen minutes per 11W, and those farther away would need one reflector per five minutes to even one minute.

If you went with the tracking system, it might actually be more financially feasible, since you would not need the everlasting multiplicity of reflectors, but merely one reflector per 11W. Well, considering real-world efficiencies, let's say in the light-to-steam-to-turbine- to-generator energy transfers, we're able to capture 2.5W per 11 (a best- case scenario), we'll need 25 reflectors per 100W used.

Another loss is, as [eulachon] pointed out, the diffraction resident in the CD (since it's not a smooth reflector, but rather a reflective diffraction grating). Say we can extract one watt of electricity per CD, and we'll be being optimistic.

--Pointed out on Helios Helper by [stonux], CD polycarbonate does not hold up well to solar UV.
-- sehrgut, Oct 25 2005


One watt? Wonderful! That's a watt that you had to burn oil/coal/nat gas for before. This is an absolutely free watt contributed by something that would have been added to a landfill anyway.
-- Worldgineer, Oct 25 2005


The real insight of this idea is not in the technical details, but in the idea that when you get A LOT of people doing one thing, that large quantity of small efforts can result in a big thing. If one solution is technically 100 times less efficient than another solution that is 1000 times more expensive, you're still 10 times ahead. (And the cost is very spread out.)
-- JackyD, Jul 28 2009


Nice one Worldgineer. I like the scale of this one. it would work best with a solar chimney/tower power plant - there's several multi-MW ones in existence, or I like the inflatable half-baked one. Fixed mirrors could work ok spread over a very large area.

Another AOL CD use would be to combine the inflatable 'parabolic' reflector idea (can't remember who posted that but it's here somewhere) with papier-mache and AOL CDs: Big balloon, cover part of it with AOL CDs, then papier- mache, then deflate = cheap solar collector for solar stoves and so forth.
-- Sandbach, May 15 2010


An interesting aside: There's a whole generation of people who will have no idea what this idea is about.
-- phoenix, May 16 2010


Has it been 7 years already (well, almost)? Luckily this idea still works, using old scratched cds or dvd or bluerays or whatever it is the kids use these days.
-- Worldgineer, Dec 30 2010



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