The distillation of water using solar energy is not a new concept. People have been doing it for literally thousands of years. Aristotle did not invent the method, but he did document the process. This is our first glimpse into the historical uses of sun to distill water.
The history of when the technique was actually invented goes back farther than recorded history. The technique had been practiced successfully for thousands of years, but it wasn’t until the 1800s that a large scale plant was built dedicated to purifying and distilling water through solar power. The plant was originally located in South America and was capable of providing water to tens of thousands of gallons of water to the local people. The system is popular in undeveloped countries around the world as a clean and efficient small scale method to purify water.
Solar distillation is a method or technique used to separate water from contaminants, or materials harmful to the human body. These materials can be naturally occurring like salt or harmful manmade contaminants. The process of solar distillation can make dirty water and salt water safe for human consumption through vaporization. When water is vaporized it is heated, which causes it to rise as steam. This leaves the contaminants and anything besides pure water separated.
It’s important to remember there is a big difference between solar desalination and solar distillation. The two terms become confused very easily and they even sound the same. The difference is the fact that for solar distillation to occur the water has to be separated from the harmful materials via vaporization. Desalination is where we see salt and mineral extracted from the water. Heat is not necessary and the process can be done with electrical and mechanical driven systems that cause reverse osmosis.
Distillation works like every other highly efficient, environmentally friend technique, it mimics nature. Distillation works by applying heat to the water (with solar distillation this is of course energy from the sun). In nature the sun acts as a heat source to dissolve water after it rains. In both cases of rain evaporation and distillation the water leaves any harmful materials behind and rises. When the temperature and pressure are perfect the evaporated water is then reformed into completely clean and purified water. For solar distillation to work you need a still, and this still needs to be able to evaporate the water to remove the impurities, and it needs to create an environment where condensation can occur. Lastly, you’ll need to be able to gather the water as condensation occurs.
Solar distillation can be explained as simple as this: water is heated by solar energy, it dissolves, leaving behind impurities and is gathered for human consumption.
As I mentioned above you will need a still of some kind to cause solar distillation. This stills vary in size and efficiency across the world. A still can be something as simple as you make at home, or something complicated enough to provide water for thousands of people. You can actually make a relatively simple still in your backyard should you choose to try an experiment.
All you need is some plastic, like trash bags, a bowl, a cup and a shovel. You’ll need lots of sunshine, and a nice hot day. You dig a decent little hole, deep enough to fit both the bowl and the cup in. In the cup you want your impure water, and your bowl can be empty. Place the bowl in the center and the cup off to the side. Once in place cover everything with your plastic material and set a rock in the middle, over the bowl. The sun’s heat will vaporize the water in the cup, and gather on the plastic. The plastic material will capture the vaporized water, and this will become drops of water that run down the plastic into the bowl.
This simple still is a perfect example of solar distillation, and is not only an interesting experiment, but a handy tool to survive with. In an emergency situation you can use a similar method to gather water from leafy green plants, and it’s safe to drink once it’s distilled. This type of still is a simple version of a single basin solar still. A real single basin solar still is built to last a lot longer, and made from much better materials.
Multi Stage Flash Distillation
A still that is a little more complicated, actually a lot more complicated, is the one used in the Multi Stage Flash Distillation. These are the big boys that use solar energy to flash impure water. These flashes distill seawater by lowering the pressure. This induces vaporization in multiple different stages, but is highly efficient for large amounts of water.
A similar mass method of distilling water is known as Multiple Effect Distillation or MED. MED consists of several different stages. First the seawater is heated by steam in tubes. This leads to partial evaporation, and lends steam to the next stage. The process is then repeated over and the steam gathered creates electricity through turbines, which actually creates the energy used for MED.
Water created through solar distillation has become a highly effective method of providing clean drinking water to countries around the world. The process of turning salt water or contaminated water into drinking water is quite simple, it’s affordable, and it can be done cleanly and efficiently. The water can then move on to being used as clean drinking water across the world. It can be used to cook with, or to bathe with. Water is necessary for any and all life, and the World Health Organization estimates that over a billion people lack clean water resources.
Solar distillation is just one of the many universally needed and appreciated tasks solar energy can provide. Solar power is so versatile, and so environmentally friendly that there is no way it won’t heavily play a role in the future planning of nations around the world.