Black Metal can give a heavy boost to the generation of solar energy
In the search for energy dependence, researchers have studied solar -thermo -electric generators (Stegs) as a promising source of generating solar electricity. In contrast to the photovoltaïschens that are currently used in most solar panels, Stegs can use all kinds of thermal energy in addition to sunlight. The simple devices have warm and cold sides with semiconductor materials in between, and the temperature difference between the sides generates electricity through a physical phenomenon that is known as the Seebeck effect.
But current Stegs have important efficiency restrictions that prevent them from being widely assumed as a practical form of energy production. At present, most thermo -electric generators are converting less than 1 percent of the sunlight in electricity, compared to around 20 percent for residential solar panel systems.
That gap in efficiency was dramatically reduced by new techniques developed by researchers from the Institute of Optics at the University of Rochester. In a study published in Light: Science and Applications, the team described their unique spectral engineering and thermal management methods to make a STEG device that generates 15 times more electricity than previous devices.
“For decades, the research community has been focusing on improving the semiconductor material used in Stegs and has achieved a modest profit in overall efficiency,” says Chunlei Guo, a professor in optics and physics and a senior scientist at Rochester’s Laboratory for Laser Energetics. “In this study we do not even touch the semiconductor materials-in-city, instead we focused on the hot and cold sides of the device. By combining a better absorption of solar energy and heat stains on the hot side with better heat disease on the cold side, we have made an amazing improvement of the efficiency.”
The new, very efficient Stegs were designed with three strategies. Firstly, the researchers on the hot side of the STEG used a special black metal technology that was developed in the GUO laboratory to transform the normal tungsten to absorb lightly light at the sun golf lengths. With the help of powerful femtosecond laser pulses to etch metal surfaces with nano -scale structures, they improved the energy absorption of the material from sunlight, while also reduced heat disipation in other wavelengths.
Secondly, the researchers “covered the black metal with a piece of plastic to make a mini greenhouse, just like on a farm,” says Guo. “You can minimize the convection and guide to capture more heat, which increases the temperature on the hot side.”
Finally, they used femtosecond laser pulses on the cold side of the Steg, but this time on normal aluminum, to create a cooling body with small structures that improved the heat discharge through both radiation and convection. That process doubles the cooling performance of a typical aluminum heat disiper.
In the study, Guo and his research team gave a simple demonstration of how their stegs can be used to feed LEDs much more effectively than current methods. Guo says that the technology can also be used to feed wireless sensors for the internet of things, portable fuel and to serve as renewable energy systems outside the countryside.
