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Solar-Powered Water Desalination Science Project

Scholasticus K Sep 19, 2020
Here is a great science project for young and budding thinkers that will use solar energy to desalinate salt water. The apparatus or materials needed for this project are readily available and is sure to give plenty of fun and inspiration to all those involved.
Water shortage is an anticipated crisis, which is bound to affect the earth sooner or later. In fact it has already struck several regions across the world. Now one of the best ways to solve the crisis is by desalinating or distilling the saline sea water which constitutes to about more than 90% of the total water available on the earth.
There are three methods of desalinating water:
  • Osmotic membrane, where water is filtered by a fine membrane which allows only the passage of water molecules.
  • Second one is the conventional distillation method.
  • The third method is to use the water in a fuel cell system where the fuel cell will split its atoms and then put it back together in molecular form.
Solar energy can be easily used to distill or desalinate salty water and get absolutely pure water. The following is a set of quick instructions which would help you to put together a simple yet fruitful, solar-powered water desalination science project.

Shopping for Supplies

Now, make a list of the following when you go out as you will need to travel to different locations for the same. Some of the items can be also found in your garage or your backyard. Ready? So here we go.
  • First off, you will need 3-5 different magnifying glasses plus a discarded dish antenna, the ones that we use for our television sets. Make sure you get one with a stand so that it stands up on the ground.
  • Second you will need 3-5 stands or small tripods or you can also use camera tripods for the purpose. These are required to hold up the magnifying glasses.
  • Next, you will require some mirrors cut in a curve which fit the dish structure of the antenna. Now another alternative is to use three straight supported mirrors, if you cannot find the ones which go into the dish properly, however make sure that you get concave mirrors.
  • Next, visit a store that sells science experiment apparatus. Here you will need to find three important things. One, a beaker or a strong and thick petri dish, a tripod or stand, over which you can place the beaker and then a distillation apparatus.
This apparatus is standard apparatus which consists of a plug or a covering that fits over the beaker, then, there is an angled (90/45 degrees) tube which is made up of glass and goes into the plug and lastly there is a proper stand or tripod which holds up the tube.
  • Lastly, you will need a cloth which is the size of the glass tube, plus some cold water, a small ink dropper, a mug and a pencil.
Gathering that stuff was the difficult part, now let's set up the apparatus.

Setting it Up

It's all about adjusting. Throughout the setting-up process, of the apparatus you will have to set it up in such a manner that, the rays of the sun are concentrated the best on the beaker. Also it's going to take hours so be prepared with a sun cap and a pair of shades/goggles.
  • First place mirrors/dish facing the sun. If you are using mirrors they should have an angle of about 80 to 85 degrees. Using a measuring tape, try to find out the mid-point of the mirror. This does not have to be very precise. However make sure that you get a round about idea. Mark it in a circle with a pencil.
Next off, place the tripod plus beaker and the distillation apparatus with salt water in front of the mirror. Cover the tube with the cloth, you can clip it on. Do not cover the remaining half which goes inside the plug or covering.
  • Now here comes the hard part, aligning the mirrors and magnifying glasses. First, align the mirrors in such a manner that they are perfectly facing the sun and the beaker is getting the best and full blast of the sunlight. Change the direction and angles of the mirrors so that you get a really good refection of the rays.

  • Wear your goggles and start arranging your magnifying glasses. Once you have set them up on the tripos, you can get a reflection from the mirrors, focus and direct the sunrays exactly on the surface of the water. This will take bit of time but aim the rays in the best possible concentrated form on to the surface of the water.
In fact, if you do it really properly, you will get a single concentrated ray of sunlight.
  • Now this one's a bit tougher and also optional. The packet of the magnifying glass will tell you the 'focal length from the focal point'. This is the length from the surface of the glass, to a point where the energy of the rays would be concentrated the maximum.
  • If you can, you can mark a point on the ground, make it a focal point with the help of a stick and your pencil. 
  • Let the point be elevated in air to make things easier. Then arrange the apparatus for distillation over that point and then arrange the magnifying lenses in such a manner that all the lenses have one common focal point, which is the beaker. You will need a scale or measuring tape for this. This way, you will get the best possible concentration of the rays.
Keep the cloth wet using the cold water and the ink dropper.
Slowly the water will turn to steam and evaporate. It will leave behind the salt and since it is lighter than the air, it will float above and enter the tube. The cold from the cloth will condense it and it will come freshwater in a desalinated form. This very process can be easily used for desalination with the help of the very abundant solar energy.