In 2012 a new technology was invented by the Rice University in the USA. Here steam is produced by using nanoparticles. This technique is meant to be implemented in the sanitation and water purification process.
For quite a long time humans produce steam by putting a heat source under the water and wait until it is boiling. For this solar evaporation process nanoparticles and a lens is used. All it needs is to put these nanoparticles in the water and concentrate the sun with the lens on them. This will heat them up so quickly that they can produce steam even when the water is near the freezing point.
The material of the nanoparticles absorbs the light over the whole spectrum, not only the visible light which human beings can see. Some of the materials used are SiO2 /Au –nanoshells and carbon nanoparticles. These two were tested on how long it takes for them to produce steam. For the nanoshell it takes 5 seconds while for the carbon nanoparticles it took 20 seconds, which is very fast as well compared to the conventional steam production. But after that the production of steam was constant.
The advantage of this technique is that not all of the water has to be heated up in the first place. All it needs is the surface of the nanoparticles which have a higher temperature than the boiling point of the water. Some steam will come into existence, will move up because of the high temperature and new liquid will get into contact with the surface.
This process is very efficient as around 80% of the sunlight is converted into steam, while the rest will heat up the liquid. Therefore this technique makes the distillation process more efficient. But there are even more possible applications for this technology. For example desalination and sterilization can become more efficient with this technology.
In 2013 the University built a sterilization engine which uses the steam evaporation technology. It is meant to be used in the developing world, where people have lack of access to clean water and electricity.
The produced engine can deal with the waste of a family with four members while the machine is used only twice in a week.
The developers hope that this technique is tested on three sites in Kenya.
As this technology is very promising in generating steam, which then can be used for a variety of purposes it would be great when this invention become widespread and used all over the world.
The picture at the bottom illustrates the process.