Author Topic: Applications for Heliostats  (Read 19556 times)

Gabriel

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Applications for Heliostats
« on: June 30, 2009, 08:07:07 AM »
I've decided to start compiling a list of all of the applications for heliostats. I have been researching them for the last year now and, naturally, have stumbled across ideas that are quite inspiring. Writing this list and presenting my own ideas for each section in one sitting, however, would be torture, so I won't try. Instead, the work will be spread across several days or maybe even weeks. Nothing is in any particular order. I just put it up as I think of it.

Of course, if anyone would like to add their own thoughts on the subject, please feel free to do so. Don't let me leave anything out. If you can think of a use for heliostats that no one else has, put it up. Thanks!  :)



To start things off, we're going to take a look at heliostats reflecting sunlight through prisms. The result of this combination is, well, just downright pretty.

Here is a link to some pictures. http://erskinesolarart.net/ There is a lot there if you just click around.

I can also think of some practical possibilities too. For example, one problem with solar cells is that their efficiency goes down as their temperature goes up. This means that it isn't feasible to increase their power output just by shining more light on them with mirrors. However, I know that solar cells are sensitive to certain frequencies (AKA colors) of light  more than others. With a prism, you could shine only the light that is useful for generating electricity on the solar cell while the other parts of the spectrum are sent elsewhere so they won't overheat it.

Something similar could be done with plants as well. One problem with greenhouses is that they can overheat easily, even in the winter. I know that plants like certain frequencies more than others, so perhaps a setup similar to the solar cell idea would work with them as well.


Thanks for reading!
More will come.
Gabriel
« Last Edit: July 06, 2009, 05:24:02 PM by Gabriel »


Gabriel

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Re: Uses for Heliostats
« Reply #1 on: July 05, 2009, 12:32:27 PM »
This isn't really a use for heliostats so much as it is just an interesting video with heliostats in it, but I'm posting it anyway.

http://www.ted.com/talks/lang/eng/bill_gross_on_new_energy.html

I find the concept of genetic algorithms fascinating. Long before I found this video, I had wondered if it was possible to use them for solar energy design. One of these days I want to write my own genetic algorithm and see if I can use it to find a way to utilize the scattered light from the sun on a cloudy day. It should be fun.  ;D

Gabriel


Davetech

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Re: Uses for Heliostats
« Reply #2 on: July 05, 2009, 02:17:01 PM »
Wow!  Fascinating indeed!    

It is so good to see genius at work for the good of mankind rather than working on better war machines. Not only an improved sterling-type engine but also combined with an intelligent light gathering device!  When he unveiled it I said "It's a flower!" Another instance of nature beating us to the punch. Should have known nature and evolution would have already produced the most efficient design.

I've never heard of genetic algorithms before, but he explained it so easily that even I understood the concept. Another step toward better AI. Future computer games that used that kind of machine reasoning might give us quite a challenge without the computer having to cheat!  ::)


I wonder if his system will be diy-able.  It sounds like they are trying to make them inexpensive, but I'm old, poor, and probably will stay pretty much that way. Hope I can build something similar from junk!

Well, back to making my rotozip mounting clamps. Thanks for turning us on to that! I'll share it with some friends I think might be interested.

___________________________________________________________________________________



Whoops... I went back and read the comments and visited some of Bill gross' sites and it seems that the video is 6 years old and the machine has been changed a lot in its development.  The sterling is out (awww man!) and it no longer looks like a flower.

I'd take any of those old sterlings off their hands if they don't want them anymore.   ::)


« Last Edit: July 05, 2009, 02:39:57 PM by Davetech »

Gabriel

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Re: Uses for Heliostats
« Reply #3 on: July 06, 2009, 06:40:02 AM »
Yeah, there are quite a few interesting videos on the TED website. I had it in my head that I was going to watch all of them because they really are very good. Of course, they are adding more faster than I can watch them.  :o I guess I'll just stick with what looks the most interesting.

A lot of the people giving talks at TED are some of the world's best innovators. It's nice getting the information straight from the source instead of from the news, which isn't exactly known to give much in the way of details.

Something I should have linked to in the first place is this site with a genetic algorithm in flash. http://www.wreck.devisland.net/ga/

It's pretty neat to watch. I Think? the red circles are supposed to be passengers in the car. If they hit the ground, the program starts over from the beginning and the car tries a different permutation. As you watch it, you will see that the success rate gradually increases.

Gabriel

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Re: Uses for Heliostats
« Reply #4 on: July 06, 2009, 01:54:07 PM »
Another use I can think of for heliostats is solar cooking. This is something I thought of while writing my heliostat program. Since up to ten targets can be programed into it, it would be easy to make one of those targets a solar cooker. Also, since they are so cheap and easy to make, a solar cooker would pay for itself very quickly.

A heliostat isn't really necessary for solar cooking, but it would definitely make things easier because you wouldn't have to move the solar cooker periodically as the sun moves through the sky. Also, it would be possible to shine the light through the kitchen window and into the solar cooker. That way, you don't have to carry your food outside to cook it.

Still another advantage is that it would be possible to use several mirrors together for cooking at higher temperatures. The fact that solar cookers aren't always hot enough is sometimes a problem. Of course, you would have to be careful when doing this as it could start a fire.

Here is a couple of sites with plans for building solar cookers. Some of them would probably need to be modified in order to work best with heliostats.

http://www.solarcooking.org/plans/

http://solarcookers.ning.com/

Take Care
Gabriel
« Last Edit: July 06, 2009, 01:56:09 PM by Gabriel »


Davetech

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Re: Applications for Heliostats
« Reply #5 on: July 06, 2009, 06:59:23 PM »
Good idea!  I've never gotten around to trying to cook with solar energy; mainly because of so many posts I've read about problems with low heat and how clouds come up just at the wrong time, and how long it took.  It seemed even at best, that solar cooking was "cooking in slow motion". 

But ganging up mirrors on your lunch is a great idea. You should be able to equal or even exceed the temps a conventional oven gets to... providing the weather co-operates of course.

If your array is micro controlled, it should be easy to prevent over heating.

Gabriel

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Re: Applications for Heliostats
« Reply #6 on: July 11, 2009, 11:57:11 AM »
This next post involves melting metal with a heliostat.

On a day with good sun and the correct setup, there shouldn't be any difficulty at all reaching the temperatures needed for melting aluminum or other metals.

I've only experimented with melting aluminum a few times and have never actually gotten around to making anything. My setup was simple. It was essentially just a garbage can filled with fiberglass insulation. In the center of the garbage can, there was a metal container filled with PerLight. In the center of the metal container, there was a piece of stove pipe holding back the PerLight, and inside the stove pipe was the heating element.

It was about the ugliest thing you could imagine, but it worked. However, it took a long time to melt, about 45 minutes. I tested how much wattage the heating element was using, and it was between 600 - 700 watts.

Now, if it were possible to concentrate the light from several heliostats into an insulated "box", I have no doubt that it would exceed 600 -700 watts of power. It could probably melt aluminum in a fraction of the time. It might also be possible to reach temperatures high enough to melt iron if you had enough mirrors.

Additionally, the sun's energy is free, propane, electricity, and charcoal are not. It might be safer in some ways too.

It's something that I definitely want to try sometime.

Here is a link to a site where someone has already done some experimenting on this subject.
http://www.foundry.ray-vin.com/fusion/fusionstory.htm



Jon

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Re: Applications for Heliostats
« Reply #7 on: July 25, 2009, 10:52:54 AM »
I thought I could post some input after reading some of the previous material.  Being that solarcells are less efficient in the summer heat and with the added light of a heliostat, it brought to mind that the cold winter time is good for solarpanels, so maby a heliostat can be used more effectively in the winter.  Maby the solarpanel is at a location where it is in shade, so a heliostat is helpful there.   A "solar tracker" for solarcooking  is a cheaper alternative to a heliostat, and some applications with a heliostat can possibly be done with manual steering (without motors), such as perhaps solarcooking or metal melting for relatively short amounts of time, say less than an hour.

Gabriel

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Re: Applications for Heliostats
« Reply #8 on: July 25, 2009, 08:02:50 PM »
Hey Jon

I hadn't thought of shining the reflected light from a heliostat onto a solar panel only in the cold winter. In the summer, it wouldn't help of course, but the winter cold might help keep the panel from getting too hot and thus losing power output.

I think you're also right about there being a cheaper alternative to heliostats as far as solar cooking is concerned. I can't remember how I found it, but there was some youtube video I watched where somebody had come up with a parabola shape that could keep the sun's reflection focused onto one spot for (I think) two hours without tracking.

Oh, and I watched a few of your videos. That wind turbine you built is pretty cool. I only wish that there was more wind where I live.

Take Care
Gabriel   

Jon

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Re: Applications for Heliostats
« Reply #9 on: July 25, 2009, 08:16:22 PM »
Thanks.  It's possible in summer that a heliostat can be used too, just as long as only the total light onto the solarpanel is say "one sun", that is only the light of the heliostat is focused onto the solarpanel in the shade.   For cooking, a solartracker similar to those for solarpanels would probably be sufficient, or just turn the cooker or have it on a "turntable" construction that can be rotated.  Also, Greenpowerscience on YouTube pointed out that solarpanels can be cooled in a glass water tank, as long as the solarpanels are waterproof... i'm guessing that perhaps a light value of 2 sun (1000W x 2 , or 2000W per square meter)  can illuminate the panels as long as the maximum rated current is not exceded.

Oh, the wind here is on and off, or is insufficient most of the time at ground level at least, and since I'm up in a building, its difficult to conduct experiements with the wind.... I went about a mile from where I live to make that video.  That project is still going, I'm thinking of putting a bearing in the hub and using some gearing/pully to increase the rotation speed of the generator.
« Last Edit: July 27, 2009, 12:57:16 PM by Jon »

Jon

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Re: Applications for Heliostats
« Reply #10 on: July 25, 2009, 09:00:55 PM »
I've been going through the topics trying to find where the homemade worm gear construction I seen yesterday was.  I currenty can't find it here or wherever it was.   I was doing a search on the internet for worm gear stuff, and found this link where nylon threading is used, and maby its usefull for someone making worm gears.  Still on topic I hope.   http://www.geocities.com/kindellism/Nylon_Worm_Gears.html?200925   

Davetech

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Re: Applications for Heliostats
« Reply #11 on: July 25, 2009, 10:13:46 PM »
Thanks for that link, Jon.  That's a great idea. I love knowing how to do stuff like that. I can imagine it being useful in a heliostat design. I think nylon is pretty weatherproof isn't it? Not sure about how it holds up to ultraviolet but it should be easy enough to make a housing for it.


Gabriel

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Re: Applications for Heliostats
« Reply #12 on: July 26, 2009, 04:46:07 PM »
I've been going through the topics trying to find where the homemade worm gear construction I seen yesterday was.  I currenty can't find it here or wherever it was. 


Do you mean this one here? http://www.cerebralmeltdown.com/cncstuff/page3/wormgear/default.htm

I guess it would be hard to make if you don't have a CNC machine, but you might be able to rig something similar. That link you provided looks like it might be easier to do though.

I originally made that worm gear to see if it would work well with a heliostat. It did work, but I decided to go with a lever arm/ leadscrew arrangement instead because it's easier to do, especially for people without CNC machines. I had to rewrite parts of the heliostat program that I am working on to do the needed lever arm calculations, but I think it was worth it.

I haven't released the new and improved heliostat program yet, but it is something I hope to do soon. 

Oh by the way, the Cerebral Meltdown site here is mine. I sometimes refer to stuff in the forums that exists on the site. I should probably be less vague though because I've come to realize that people find these forums without knowing that my personal posts are oftentimes just an extension of what I have put up on the site. I wonder how much confusion I've caused because I'm too lazy to post a link to what I'm talking about. ;D

Cheers
Gabriel

Jon

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Re: Applications for Heliostats
« Reply #13 on: July 26, 2009, 06:56:29 PM »
Your right, that is the gears I seen.  Now I'll try to look on Google what the "lever arm" thing/mechanism that
can be used in place of a worm gear is - I imagine it's some sort of "speed reduction" method like a worm gear. Thanks.

Gabriel

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Re: Applications for Heliostats
« Reply #14 on: August 05, 2009, 08:06:31 PM »
It's been awhile since I've posted any of my own ideas for heliostat applications. I haven't run out, I've just been busy with other things.

I found this instructable for using hot air from you attic to help dry your clothes in the dryer.
http://www.instructables.com/id/Summer-Energy-Savings-by-Modifying-Your-Electric-C/

Granted, you can just hang them up on a clothes line, but that does take a fair bit of time out of the day.

I suppose one thing you could do with the heat gained from a heliostat is to feed it into a dryer to dry your clothes.  I checked the temperature of the inside of my dryer, and it was 130 degrees F.

I was playing around with a solar cooker that I have been working on, and the temperature of the inside of the cardboard box it was heating got up to 110 degrees without much trouble. The box wasn't even sealed off or insulated, it was just plain old cardboard. That really isn't too far off from the dryer's temperature. This was with just one mirror too.

Using the instructable above, I may be able to find a way to feed the heat from the solar cooker to the dryer.

Solar cookers are pretty neat devices. I've only built the reflector so far, but it certainly does work. I can feel it heat up at the focal point instantly when I point it towards either the sun or the heliostat.

In any case, clothes dryers are one of the most expensive appliances to run because of the power they consume. Being able to heat them with something other than electricity would be awesome.