Sustainable Issue: Energy Efficiency
Technology: Butterfly wing inspires photovoltaics: Light absorption can be enhanced by up to 200 percent. Sunlight reflected by solar cells is lost as unused energy. The wings of the butterfly Pachliopta aristolochiae are drilled by nanostructures (nanoholes) that help absorbing light over a wide spectrum far better than smooth surfaces. Researchers have now succeeded in transferring these nanostructures to solar cells and, thus, enhancing their light absorption rate by up to 200 percent.
Scientist reproduced the butterfly’s nanostructures in the silicon absorbing layer of a thin-film solar cell. Subsequent analysis of light absorption yielded promising results: Compared to a smooth surface, the absorption rate of perpendicular incident light increases by 97% and rises continuously until it reaches 207% at an angle of incidence of 50 degrees. However, this does not automatically imply that efficiency of the complete PV system is enhanced by the same factor. Hence, the 200 percent are to be considered a theoretical limit for efficiency enhancement.”
Prior to transferring the nanostructures to solar cells, the researchers determined the diameter and arrangement of the nanoholes on the wing of the butterfly by means of scanning electron microscopy. Then, they analyzed the rates of light absorption for various hole patterns in a computer simulation. They found that disordered holes of varying diameters, such as those found in the black butterfly, produced most stable absorption rates over the complete spectrum at variable angles of incidence, with respect to periodically arranged monosized nanoholes. Hence, the researchers introduced disorderly positioned holes in a thin-film PV absorber, with diameters varying from 133 to 343 nanometers. The scientists demonstrated that light yield can be enhanced considerably by removing material. According to the researchers, however, any type of thin-film PV technology can be improved with such nanostructures, also on the industrial scale.
Thin-film PV modules represent an economically attractive alternative to conventional crystalline silicon solar cells, as the light-absorbing layer is thinner by a factor of up to 1000 and, hence, material consumption is reduced. Still, absorption rates of thin layers are below those of crystalline silicon cells. Hence, they are used in systems needing little power, such as pocket calculators or watches. Enhanced absorption would make thin-film cells much more attractive for larger applications, such as photovoltaics systems on roofs.
Public/ Government body
Commercial building users
Deployment / Implementation:
Step one: Showcase the reliability of the technology to the public and private entities. Attract more investors and spread awareness about the usage to this technology.
Step two: Set up some full-scale prototype units to prove the principles in real-world conditions.
Step three: Find companies that could use this technology in their buildings to demonstrate the efficiency of the technology.
Response to Another post
Plastic Roads by Drb2171
Plastic Roads, are found to perform better compared to those constructed with conventional bitumen. This means no more stripping and no potholes. Plastic roads will also address the major issue of disposing plastic waste. But as I read more on plastic roads I learnt that the first rain will trigger leaching as plastics will merely form a sticky layer and once laid plastic roads are inert. These problems need to be addressed before implementing plastic roads on large scale.