New Solar Energy Facts - Carbon Nanotubes For Solar Energy Systems

With the need for alternative energy high on every priority list, engineers in every country are working with the hope of economizing solar energy so that it can be available even to modest businesses and individuals. Solar energy technology is improving, and one of the most spectacular improvements to date is the introduction of carbon nanotubes (hollow tubes of carbon atoms) into new solar energy systems. Carbon nanotubes are not recent discoveries, they were introduced several years ago and they were popularized for their strength. It was recognized that they could be used in the construction of airplanes, lighter and stronger automobiles, buildings, and even soft balls. But, new solar energy facts show that the introduction of carbon nanotubes into solar energy systems allows the level of energy storage of those systems to increase 100 fold in comparison to regular photovoltaic solar cells.This finding is credited, for the most part, to a group of MIT chemical engineers. Through their research, they found that by using carbon nanotubes, solar energy can be super concentrated. Their studies showed that the nanotubes could form antennas that are capable of capturing and focusing light energy more effectively thus allowing smaller and more powerful solar arrays.According to a recent study released in the Journal of Nature Materials by Michael Strano, Associate Professor of Chemical Engineering at MIT and the associated research team, the carbon nanotube antenna, or as they call it the "solar funnel", might also be useful for other applications that require concentrated light. Among these applications, they specifically made mention of night vision goggles and telescopes.At the most basic level, the way this process works; solar panels generate electricity by converting photons (packets of light energy) into an electric current. The nanotube boosts the number of photons that can be captured and then transforms this increased level of light into energy that can be funneled into the solar storage cell.What the MIT team accomplished was the construction a special antenna consisting of fibrous ropes, only 10 micrometers (millionths of a meter) long and 4 micrometers thick. Each fibrous rope contained about 30 million carbon nanotubes. These ropes or micro fibers were made up of two layers of nanotubes with different electrical properties or bandgaps*. The inner layer of the antenna contained nanotubes with a smaller bandgap than the outer layer. This is important because excitons flow from high energy to low energy or, in this specific case, from the outer layer to the inner layer where they can exist in a lower, yet still excited, energy state.So, what does all of this mean? Well, when light energy strikes the antenna, all of the excitons flow to the center of the fiber where they are concentrated and stored. Better methods of energy storage translate to improved efficiency and improved efficiency means more economical energy resources. As solar power becomes more economical more people will migrate to solar panel installation and solar powered homes and businesses.*Electrons can exist in any material at different energy levels. When a photon strikes the surface of the material it excites an electron to a higher energy level that is specific to that particular material. The interaction between the excited electron and the hole it leaves behind is called an exciton. The difference in energy levels between the hole and the electron has been labeled the bandgap.