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Revision as of 14:33, 7 December 2007 by Jaran Ellermeyer (New page: == Solar still basics == Solar stills are a type of appropriate technolgy that are used to distill water using the power of the sun. They come in three basic types, cone shaped, boxlik...)
Solar still basics
Solar stills are a type of appropriate technolgy that are used to distill water using the power of the sun. They come in three basic types, cone shaped, boxlike, and pit. The most sophisticated being the box like and the least sophisticated is the pit. In any solar still the basic layout is some sort of collection device that captures rainwater. Covering this will in most cases be a sheet of glass or transparent plastic which allows solar radiation to pass through but not escape. This causes the water to evaporate and condense on the cover material. This process removes impurities such as salts and heavy metals as well as eliminates microbiological organisms. The end result is a supply of fresh, clean water.
Solar stills have been used for Hundreds of years. The earliest known examples date back to 1551 when Arab alchemists used it. In 1882 the first conventional still was invented by Charles Wilson. It was a massive solar still plant which was used to supply freshwater to a mining community in northern Chile. Today hundreds of solar still plants and thousands of individual solar stills have been built around the world.
Generally, solar stills are used in areas where piped or well water is impractical. Such areas include remote locations or during power outages. In areas that frequently lose power, solar stills can provide an alternate source of clean water. A large use of solar stills is in developing countries where the technology to effectively distill large quantities of water has not yet arrived. The drawback is that they produce a relatively small amount of cleanwater for an individual still. Another application for solar stills is survival. Simple solar stills can be created using basic elements from camping gear and the environment. Stills for survival would generally be the pit type since they are they simpilest to produce. Moisture from the ground can be extracted but to increase the available moisture, water must be added inside or along the edges of the still. Where no water sources are readily available, urine or shredded vegetation can be used inside the pit. However makeshift solar stills often do not provide enough water for longterm survival, but can prevent dehydration for short periods of time.