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This is just something simple, but some summers ago I made the "Fun-Panel" from the solarcooking.org plans. I was surprised how well it worked, was actually able to fully cook some small stuff. A fun and recommended geeky project.

If you get tired of listen for radio waves, and looking for "wild feed" TV signals, then I'd suggest you go green and use it as a (parabolic) solar oven to cook with.

There are plenty of plans and ideas online for you to try. Some easy metal work, and food cooked for free as a reward, what more can any guy ask for?

If you make a giant solar cooker, make sure to try the opposite too... use space as a heat sink and try to make ice.

http://solarcooking.org/plans/funnel.htm

Perhaps you replied to the wrong post.

What kind of engineer? Sanitation enginneer? That's just utterly rediculous.

I have no idea, he's not my friend. He's the friend of the person I replied to.

No spud, you don't run electric space heaters, dryers and stoves off solar. The first thing you do is get rid of all the overconsumptive stuff.

Space heaters, whether electric or gas, aren't very efficient. Radiant floor heating is more efficient. Solar dryers are the most efficient as well, the oldtime version is the cloths line. And Solar cookers are quite good. As for overconsumption, when designing for off the grid living, the first thing that's usually focused on is conservation, people reduce what's needed and then what is needed energy efficient models are used.

The Open Source community could build something that would make a real difference in the developing world --

if we stopped dicking around with laptops and started collaborating on high-yield, low-input agricultural methods, water reclamation systems, sanitation, and low-conventional-energy devices generally. Great examples: the discovery that pouring water through silk provides enough filtration to substantially reduce the incidence of cholera; the development of solar cooking technologies to help stop deforestation and prevent women from having to gather firewood alone in regions with prevalent rape gangs.
THAT is the kind of tech that we should be working on collaboratively. Though there isn't any Linux involved.

OLPC is a great idea, but it doesn't actually address the real problems of the developing world--which aren't web browsing, intuitive programming, and videoconferencing, but security, environmental repair, and conventional-energy-independent development! All this talktalk about laptops has always been the well-meaning but sorely out of touch "help" provided by people who know tons about OSS but have no idea what people in developing countries really need.

Those are valid criticisms of lifestraw, I'm afraid.

Better options are things like Solar Water Pasteurization which don't require a repurchase for each family member and reduce other problems, like firewood supply.

http://solarcooking.org/pasteurization/default.htm

I do agree that the general issues around water supply need better "quick fix" technologies, however. We can't wait for society to change, we have to move on technology. Now.

It just has to be the right technology.

I think there's a misconception about deserts. (They generally are not simply dunes of sand. There's a *lot* of plant and animal life in the Sonoran ecosystem, for example). Anyway, where I live, according to my local power company we have up to 17% solar power in the summer. I have two solar cookers which work really well for making soups and sauces. Exactly like these: http://solarcooking.org/images/hflame1.jpg
  I also have a roof-mounted solar water heater, part of a hybrid system (I have a gas water heater but it does considerably less work when the solar heater is working, which is almost all the time.) Yes we have hot water at night. The rooftop heater looks like a skylight. Okay, so I live in a desert city with 300 days of sunshine a year. Love it.

The reason I say the Universe is making it hard is that it has not been an easy task to harness solar power in a cost-effective way.

This is why the people who are promoting Solar Cooking are doing so in third world countries. Solar cooking means they don't have to spend so much time looking for firewood, and they can keep their trees. Plus, it helps stave off global warming a little bit.

Listen, we have the technology we could turn the sahara into an icebox. how you say? simple, http://solarcooking.org/funnel.htm "As a result, the cooking vessel now becomes a small refrigerator. We routinely achieve cooling of about 20 F (10 C) below ambient air temperature using this remarkably simple scheme."

and that's without designing the solar cooker specifically to 'cool' water into ice, using a 'heat pump' type device to accelerate the radiation of heat from say, water in a vaccume 'insulated' snow formation chamber etc. once you've got a few thousand of these machines creating 'snow' all night long, the snow itself will 'reflect' enough heat back, especially if the device can focus 'away' from the sun to 'continue' to draw the cooling power of space to maintain a 'cool draft' to preserve the snow from melting. all without using electricity. imagine if the devices did utileze small photovotaic piezeo electric coolers by 'daylight' hours to further enhance the 'radiation' of heat into space.

yeah, we could hold the winter olympics in cairo ;)

If you're interested in asteroid deflection, Jay Melosh has a few ideas.

Including: "Deploying a giant parabolic mirror to concentrate the sun's rays and vaporize rock on the surface of the asteroid. The vaporized material flies off at high speed and generates a re-coil action that pushes the asteroid, slowly but surely, in the opposite direction."

Which is great, because the parabolic mirror can double as a way for Bruce Willis to cook and refrigerate his food while he's there.

From a section on the solar funnel cooker website:

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In September 1999, we placed two funnels out in the evening, with double-bagged jars inside. One jar was on a block of wood and the other was suspended in the funnel using fishing line. The temperature that evening (in Provo, Utah) was 78 F. Using a Radio Shack indoor/outdoor thermometer, a BYU student (Colter Paulson) measured the temperature inside the funnel and outside in the open air. He found that the temperature of the air inside the funnel dropped quickly by about 15 degrees, as its heat was radiated upwards in the clear sky. That night, the minimum outdoor air temperature measured was 47.5 degrees - but the water in both jars had ICE. I invite others to try this, and please let me know if you get ice at 55 or even 60 degrees outside air temperature (minimum at night). A black PVC container may work even better than a black-painted jar, since PVC is a good infrared radiator - these matters are still being studied.

I would like to see the "Funnel Refrigerator" tried in desert climates, especially where freezing temperatures are rarely reached. It should be possible in this way to cheaply make ice for Hutus in Rwanda and for aborigines in Australia, without using any electricity or other modern "tricks." We are in effect bringing some of the cold of space to a little corner on earth. Please let me know how this works for you.
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This is an experiment you can conduct yourself. It may be that without advanced insulation (maybe straw wasn't enough?) one couldn't obtain ice in the desert, but given good modern materials the physics suggests that it would work well.

-Adam

I'm not sure of the time scales involved but you
can make ice this way in the desert.

The time scales involve mostly the quality of the insulation and the night-time temperatures. The reachable drop or delta from night temperatures depends on the quality of insulation. Straw and what not? Maybe 20 degrees.

http://solarcooking.org/funnel.htm

(Yes, mostly re. a solar cooker, but they also made ice. See about 1/4 up from the bottom or search for "cooler".)

sdb

Considering the main point of this system is to remove pathogens from the water, it'd probably be cheaper and more reliable to use fire or even funny square shaped tinfoil hats.

You can also build one of these to do your cooking for you. They can be build by various means for a pretty low price. Combine some collectors and a lens and you'll have a nice little material heater.

Also, I don't think this will ever see use in poor countries. First, the geography must be just right for there to be enough sunlight, this eliminates a lot of places.

IANAMedProf either but I'm sure that some types of surgery carried out by laser can't really be done any other way.

The cost of sending people to train others how to use the equipment is probably much greater than the cost of the equipment itself... some organisations do think it's worth it for other solar technologies, so it's quite possible it could work here. $1000 for something reusable without need of sterilization at very high temperature for extended periods of time (*how* much fuel is needed each time?!) isn't that excessive.

plain old sterilized surgical stainless steel

the collector must track the sun as it moves, and this implies some sort of motor. Hence I would not go so far as to say that this could be used anywhere without power. Sure, it could run on batteries,

Some people have asked why we don't generate energy with one of those things. Well, we don't use a single parabolic mirror, because it is hard to build a very large one. Instead, we use multiple mirrors all angled toward a focal point, like this:

Solar Power Tower

While the website says that it is in use, the last few times I have driven by on (on my way to my parents house in Bako), it hasn't been exceptionally bright. I remember it in the late 80's, early 90's, the top of the tower looked like it was white hot (at the focus), and when they would move the mirrors away, above the tower, you could "see" a spot of "boiling" air - it looked like the wavyness you see rippling off a hot car, from the heat refraction, but hovering at a point in mid-air. Very impressive shit.

That's not all, though - want to build such a device yourself, for cooking perhaps? Check this...

Still not enough? Want to build a "real" solar furnace?

Go here!

Have fun, and don't burn yourself!

Worldcom - Generation Duh!