Solar Energy Experiment: Water From Plants

This solar energy experiment draws water from plants using only the power of the sun. With just a shovel, a plastic sheet and a bowl it is possible to get fresh water from virtually any vegetation.

Materials Needed: You will need the following:

* shovel
* a clear plastic sheet at least 75cm x 75cm (25 in x 25 in)
* 10 - 15 heavy stones
* a clean jar
* a pebble
* any kind of green plant matter


Step 1: Dig a hole in the ground approximately 30cm (10 in) deep and 60cm (20 in) in diameter. Collect any fresh green vegetation from the nearby area and fill the hole with them. Weeds and / or lawn clippings are ideal in a suburban environment.

Step 2: Place the jar in the CENTRE of the hole and make sure it has a firm foundation, ie it is resting on the ground and not on the vegetation.

Step 3: Cover the hole with the clear plastic sheet. Any colour plastic sheet will work, but with a clear one you can SEE what is happening. Use the stones to weigh down the EDGES of the plastic sheet.

Step 4: Place the pebble in the CENTRE of the sheet so that it makes a dip in the plastic sheet, which must be EXACTLY above the jar in the hole.

Here is what it will look like:

solar energy experiment

What is Happening?

The heat from the sun is trapped by the plastic sheet. This makes the temperature in the hole rise. This in turn dries of the vegetable matter. The water vapour then reaches the plastic sheet (since hot air rises) where it condenses to form water. It does this because although the plastic sheet traps the heat, it is exposed to cooler air on the outside of the hole which makes it be at a lower temperature than the air in the hole.

The condensed water vapour runs down the underside of the sheet to the point where the pebble is sitting, and then drips into the cup.

IMPORTANT: While this is a good solar energy experiment and also has survival value, it is strongly recommended that your child DOES NOT DRINK THE WATER. It could contain toxins from herbicides or another source that are carried with the water when it evaporates. The plastic sheet may also be dirty. If you want a version of this solar energy education experiment where you CAN drink the water, see this water science experiments Water Purifier.

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