1. Field of the Invention
This invention relates to the use of solar energy to boil and purify drinking water.
2. Description of Related Art
About two billion people do not have access to clean, fresh water. Most of earth's water cannot be used for drinking, cooking, or bathing, due to dissolved natural salts, bacterial or parasitic contamination, or chemical contamination. While unpurified water can often be used for some purposes, it must be purified if it is to be used for drinking Water purification can be done by a number of different processes, including reverse osmosis and evaporation-condensation processes.
Although effective processes for water purification are well known, these processes are also energy intensive. For example, in evaporation-condensation processes, water is typically heated to convert it to steam and then condensed back into the liquid phase. The heating process kills many organisms found in unpurified water, but requires a great deal of energy. Unfortunately, many of the places that do not have clean, fresh water also do not have access to reliable sources of power or established power grids. A common solution to the lack of reliable power sources, particularly for sunny areas of the globe, is to use photovoltaic panels to convert solar energy to electricity.
Photovoltaic cells cannot use all of the wavelengths of light in the solar spectrum to produce electricity. They particularly have trouble using infrared and ultraviolet wavelengths of light, and even for those wavelengths that can be converted into electricity, the conversion is not particularly efficient. An average solar panel is capable of converting only about 20% of the solar energy it absorbs into electricity; the other 80% is lost, typically as heat energy. Solar panels are also relatively expensive.