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Friday, July 14, 2006

How To Build a Solar Generator

Continued from page 1

By Kevin Bullis
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Repurposed auto parts aren't the only way to go. Amy Sun, a graduate student in MIT's Media Lab, has designed an inexpensive system that uses heat from a solar concentrator to drive a type of turbine originally patented by Nicola Tesla. Rather than making complex, difficult-to-manufacture bladed turbines, Sun turned to the Tesla turbine, which consists of simpler flat disks stacked like records on a central shaft. The disks are carefully spaced to allow steam to flow between them. As the steam flows, friction between the steam and the surface of the disks causes them to rotate. "Once I have rotational shaft work, I can couple it to almost anything -- an air pump, compressor, fan, mixer, grinder, sewing machine, refrigeration compressor, and, to power those very few things that are truly electric in nature, an electric generator." She calculates that this system, which she says is simple enough for an eight-year old to make, can produce cheap power.

Of course the overall economics of these solar generator systems depend on how long they will last and how much maintenance they will require. The lifetime for Orosz's system could be quite good, since it uses parts designed for rugged service in vehicles. It also works at relatively low temperatures that, in addition to making it safer and easier to work with, won't strain the performance limits of the plumbing used.

Having already built a working prototype, Orosz's next step, which he hopes to accomplish starting this September in Lesotho, is to optimize manufacturing and set up a financing system, drawing on a recent $100,000 World Bank grant, to make the system affordable to villagers who would likely use the generator in a community center and as a battery-charging station.

Although their system was originally designed for Lesotho, Orosz and his colleagues believe it might appeal to amateurs elsewhere. "Backyard tinkerers could build it themselves. No doubt about it," says Amy Mueller, an MIT graduate student who's taken on a leading role in Orosz's project. "Matt's dad has one of these that we built to heat his Jacuzzi."
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Comments

  • Parabolic reflectors
    Guest (Bill) on 07/14/2006 at 12:00 AM
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    A book was published in the 70's outlining simple methods of producing parabolic reflectors.  As sun trackers were not readily available then, a clock mechanism was used control the orientation of the reflectors.
    Rate this comment: 12345
    • car to elaborate?  How do you make one?
      Guest (Dale) on 07/14/2006 at 12:00 AM
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      I was thinking that the reflector would be the most expensive thing in this solar energy solution.  Can these be made by someone with access to the local college metal shop?  I'm thinking 50-gal steel drum cut in half, or something like that...
      Rate this comment: 12345
      • Cheap Easy Parabola
        Guest (Andre) on 07/18/2006 at 12:00 AM
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        1
        Glue aluminumized mylar (reflective plastic sheet) to a piece of formica and bend, cut end blocks to form the shape and ther at alle you go. Not expensive
        Rate this comment: 12345
        • Parabola
          Guest (John Handy) on 07/19/2006 at 12:00 AM
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          Easy and cheap parabola but the shape is critical. Where Can I get a pattern for the end blocks?
          Rate this comment: 12345
          • parabolas
            Guest (Maker) on 07/19/2006 at 12:00 AM
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            A parabola is just one-half of an elipse cut the short way.  To make an elipse, drive two nails into a sheet of plywood at each of a straight line (length doesn't matter really). Then make a loop of string that can hook on one nail and extend past the second nail some distance, say 30% the distance between the two nails (this distance also doesn't matter).  Then hook a pencil inside the loop and trace around the two nails, keeping the string taught always.  This will draw an elipse.  If you cut the elipse in half halfway between the nails, each half will be a parabola with the focal point at the nail.
            Rate this comment: 12345
            • a 'half elipse' is not a parabola
              Guest (jimbo) on 07/20/2006 at 12:00 AM
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              anybody remember graphing parabolas in high school math?  get a presentation pad with gridlines from an office supply store and graph some parabolas.  y=x^2
              Rate this comment: 12345
              • More on Parabolic Math
                Guest (postman) on 07/26/2006 at 12:00 AM
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                To go one further, for a solar trough collector it's also convenient to place your collection pipe level with the endpoints of your parabola.  This is good for providing mechanical support and easily finding your focal point.  This requires an extension to the basic parabola formula.  Unfortunately I did that derivation 30 years ago when I was far more mathematically astute and don't have it handy any more.
                Rate this comment: 12345
                • Parabolic math and things
                  Guest (riverrock) on 07/28/2006 at 12:00 AM
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                  Shouldn’t the parabola used in such a system be very accurately built?

                  I understand that sun rays hitting points on the parabola will reflect to the focus, thus heating the pipe carrying the liquid.

                  I found free sites on the internet that provide sun azimuth and vertical angles from any location, based on the time of day, any day.

                  I believe that a light weight hard, but flexible material covered with a highly reflective surface material could do the job.

                  What I’d like to learn is how a steam turbine would be connected to the feed pipe at the focus?

                   
                  Rate this comment: 12345
                • Parabolic Math
                  Guest (Charlie Queen) on 08/07/2006 at 12:00 AM
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                  The formula for a parabolic curve is X * x = 4 * P * Y. 
                  To solve for Y, divide X squared by 4* P, where P is the focal point.  This will give you the parabolic curve for a given focal point.
                  Rate this comment: 12345
              • Re: a 'half elipse' is not a parabola
                falk on 10/16/2006 at 9:08 PM
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                If the ellipse is eccentric enough, it will be close enough to a parabola to do the job.

                Ways to draw an ellipse:

                http://www.uwgb.edu/dutchs/MATHALGO/Ellipses.HTM
                Rate this comment: 12345
                • how to construct a parabolic concentrator curve
                  john milton on 03/02/2007 at 11:43 PM
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                  1
                  Avg Rating:
                  4/5
                  1 Obtain a piece of plywood

                  2 Draw a straight line close to one edge (will call this the "base line")

                  3 Partially hammer in a nail some distance above the base line. this will be the focal point.

                  4 Obtain a framing square (the metal L shaped thing carpenters use).

                  5 Place the square so that the outside edge of one leg is touching the nail and the outside corner of the square is touching the base line.

                  6 Draw a line along the outside edge of the leg of the square not touching the nail, then extend this line to the edge of the plywood

                  7 Reposition the square to a new location that still meets both the criteria of step #5

                  8 Draw a new line as per step 6

                  9 repeat steps 7 & 8 many times, the line segments you draw will describe the parabola (in fact each of them is a tangent to it at some point)
                  Rate this comment: 12345
                • Re: a 'half elipse' is not a parabola
                  jsixis on 09/05/2008 at 10:19 AM
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                  5/5
                  Close enough is not good enough.
                  If you can't increase the "suns" hitting the pipe then you just made a fancy batch heater so you'll get 150 degree water vs 400.
                  I just spent 1 week making 2 collectors using a freeware calculator, after checking it with a laser pointer it turned out it was for a solar stove.
                  It did focus 30 degrees onto the pipe and if exactly lined up I could get steam in 15 minutes
                  but if the rest of the parabolic dish actually hit the pipe steam would be almost instant.
                  Rate this comment: 12345
              • Re: a 'half elipse' is not a parabola
                dinesh13 on 10/03/2008 at 11:22 AM
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                How to draw parabola with it's exact focal point, kindly confirm.
                Rate this comment: 12345
            • Re: parabolas
              dinesh13 on 10/03/2008 at 11:12 AM
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              4
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              5/5
              Kindly arrange to send details about design and fabrication of Solar parabolic concentrators on aditya1369@gmail.com
              Rate this comment: 12345
        • cheep and easy
          Guest (scott) on 07/21/2006 at 12:00 AM
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          I have about 100 sheets of mylar.
          what kind of glue should i use to glue it to the formica
          Rate this comment: 12345
          • Re: cheep and easy
            Romawat on 09/27/2006 at 2:09 AM
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            5/5
            Someone asked how to glue the mylar to the formica.  You can apply it just like window tinting: spray the formica with soapy water, carefully apply the mylar, and squeegee the excess water to and out the sides.  Blot the excess liquid and tape the seams (use aluminized tape if you really must), to keep the mylar from peeling.  As long as the edges remain taped, the mylar cannot come away from the formica.  Smooth formica is best and will provide the superior reflection.
            Rate this comment: 12345
    • Parabolic Reflectors
      Guest (GalaxyM100) on 07/15/2006 at 12:00 AM
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      I think nonimaging optics would solve the tracking problem and reduce costs further.
      Rate this comment: 12345
      • Re: Parabolic Reflectors
        Rob-in-texas on 09/08/2007 at 7:31 PM
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        1
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        5/5
        I worked at a solar collection siste in New Mexico in the 80s.. The tracking device is actually simple ot make. simply use 4 photo-optic sensors in a box with a clear cover facing the sky. The tracking boxes were actually mounted to the tops of the troughs.
        Align was achieved by having two sensors in the sun, and two still in the shaded area of the sensor board.. think of it as a rectangle with a smaller square opening.. the output of the photo sensors drove relays to reversible electric motors.
        Rate this comment: 12345
    • Parabolic dish
      Guest (John) on 07/31/2006 at 12:00 AM
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      A inexpensive parabolic dish can be purchased from Edmund Scientic. They have a pretty short focal length, 3.5". But for $50 for a 24" dish is pretty cheap.
      Rate this comment: 12345
    • Re: Parabolic reflectors
      MyTonyTiger on 12/31/2007 at 5:27 PM
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      1
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      3/5

      You could use an old satellite dish. You know, the old 6, 8, 10, or 12 foot dishes hardly anyone uses anymore. Set up correctly, the actuator (motor) on each one could easily track the sun. You could even run the plumbing through the center of the dish up to the focal point and back.

      Just an idea. ;-)
      Rate this comment: 12345
    • Re: Parabolic reflectors
      aymaneman on 01/17/2008 at 6:42 AM
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      1
      i love to be have a knoleg abuot any thing new , and i like wht yo have in your web set 
      Rate this comment: 12345
    • Re: Parabolic reflectors
      dinesh13 on 10/03/2008 at 10:59 AM
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      4
      Avg Rating:
      5/5
      Rate this comment: 12345
    • Re: Parabolic reflectors
      dinesh13 on 10/03/2008 at 11:07 AM
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      4
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      5/5
      Dear sir,

      Kindly arrange to send details about Parabolic trough design and clock machanism for tracking.
      I would like to fabricate parabolic trough in my work shop hence furnish the details.
      Kindly send the reply on my e-mail ID - aditya1369@gmail.com

      Thank you,

      Dinesh.
      Rate this comment: 12345
  • Oh good.  They've solved global poverty.
    Guest (WOV) on 07/14/2006 at 12:00 AM
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    Another set of engineers saying that because they've made this water pump / electrical generator / seed harvester / cardboard house / what have you, that *this* will solve why rural poor populations don't have electricity.

    It's not a technical problem.  It's a social one.  (Actually a bunch of them.)  And as long as engineers continue to come up with new widgets that will solve it for sure this time, it will still be with us...
    Rate this comment: 12345
    • WOV is right
      Guest (MDEX) on 07/14/2006 at 12:00 AM
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      These people had the same opportunities as other races to advance, they are just too lazy to do anything. You'd think that because they are poor and stuff, that they would be motivated to come up with ways to help themselves. Instead, engineers of superior races do all the brainwork.
      Rate this comment: 12345
      • poor and stuff
        Guest (Steve) on 07/14/2006 at 12:00 AM
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        Uh huh... you sound pretty advanced yourself.

        The idea is to bring those who are without, no matter what the reason,  the ability to grow.  It isn't a matter of race.  If you have a doubt, check out the local trailer trash parks.

        I hope they continue with their work.
        Rate this comment: 12345
      • It's not a race thing
        Guest (Ruben) on 07/14/2006 at 12:00 AM
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        It's difficult to make great strides in technology when you have to worry about where your next meal will come from or if you have clean water to drink.  You make a bad name for your "superior race".  Isn't it more superior to help others and share your knowledge for the good of humanity?  Thank goodness the engineers who worked on these solar generators were more openminded than you.
        Rate this comment: 12345
      • Wow, that's totally racist...
        Guest (shocked reader) on 07/14/2006 at 12:00 AM
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        ...
        Rate this comment: 12345
        • MDEX was joking
          Guest (Mike Hal) on 07/14/2006 at 12:00 AM
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          I thought MDEX made a good show of sarcastic wit to loosen the humorless up a bit - relax already, it's a cool idea...  breaking down the institutionalized pricing of an industry like Photov's - seemingly in the 'lucrative' phase - by industrial supply 'dumpster diving' is the key here.
          Rate this comment: 12345
          • too much credit
            Guest (Dan) on 07/16/2006 at 12:00 AM
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            I think MDEX is being given far too much credit for his/her intellectual and humanitarian capacity.
            Rate this comment: 12345
        • Its a social problem
          Guest (Dave) on 07/19/2006 at 12:00 AM
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          They have a social problem. When people going to those poor cities for diggin a well, they have to check why they dont dig well before by themselves. Often, its a social problem that cause lazy behavior and ... 3000 years ago they was diggin well, so they can now too. Speak to engeneer without border for more details.
          Rate this comment: 12345
          • Not about race...its about ease
            Guest (Jeff) on 07/26/2006 at 12:00 AM
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            They dug the wells 3000 years ago because back then there weren't liberal helpniks to enable their lazy behavior. I say giving them some good plans is a move in the right direction but making these things and giving them away goes over the line.
            Rate this comment: 12345
        • not racist
          Guest (dudevato) on 07/29/2006 at 12:00 AM
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          there's only one human race, we are here together
          Rate this comment: 12345
      • WOV may not be all "right"
        Guest (Luke) on 08/03/2006 at 12:00 AM
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        I believe there are a lot of smart people out there but I don't think MDEX or WOV are very educated.  Would you think your PEOPLE would be so great if your country is constantly being plagued with drought, war, and disease.  Where do you think all their oppourtunity for advancement would come from?? 
        Rate this comment: 12345
    • Solar Generator
      Guest (CLB) on 07/14/2006 at 12:00 AM
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      I think this is more of a social economic problem however widgets have historically helping focus populations. I also think every discipline needs to do its part to make an impact, Engineers engineer. The growing need for power is a profound problem and will require many solutions.
      Rate this comment: 12345
      • Don't diss this development
        Guest (CKE) on 07/14/2006 at 12:00 AM
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        Prior 1st world efforts at aiding the 3rd world have largely been failures. This is because they have centered on giving resources to the local governments to implement large publicly shared infrastructure projects. They failed because of the usual reasons: corruption, larceny, incompetence, civil strife, etc. These new efforts are directed instead at the ultimate end users, the villagers. These end users don't have, and don't need any involvement of their governments to implement these tools. Witness how well the cellphone technology has spread into daily life in these countries, they now outnumber the 1st world in cellphone usage. Because the final users are responsible and capable of operating these devices, and because they will be the direct beneficiaries of its operation, this technology approach, and others like it, will be successful.
        Rate this comment: 12345
      • Re: Solar Generator
        Gopakumar on 09/27/2006 at 1:00 AM
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        Dear Sir,
        I like too much your technology. I am from Inida now I am working in U.A.E.

        I would like to implement your SOLAR GENERATOR SYSTEM  for poor villagers in India and Site workers in. U.A.E.

        I would like to get technical suport from you for the your greate new technology.

        I am looking forward to hearing your replay.

        Have a nice day.

        Thank with Regards,

        Gopakumar
        Giffin Traffiks LLC
        Section head- Electrical
        Abu Dhabi
        United arab Emirates.
        Tel-00971 2 5553141
        Fax-00971 2 5553992
        Mob - 00971 50 5215644
        Emai-goppikka@yahoo.com
        www.signfab.ae
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        • Re: Solar Generator
          marketofwgmax on 02/04/2007 at 10:52 PM
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          2
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          5/5
          I know this company has already put this products into bulk production and got big sales volume,www.duxlite.com
          Rate this comment: 12345
    • True - Solving Rural Poverty Requires More
      Guest (The Teacher) on 07/14/2006 at 12:00 AM
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      The solution to the privations of the rural poor is not "inexpensive gadgets". The solution lies in a worldwide economic system that can build wealth for every family. It is not socialism, and current capitalist systems are too brutal and inefficient. WeMSA is presenting a workable, innovative