Scholars at the Institute of Optics at the University of Rochester have created a solar thermoelectric generator that is 15 times more efficient than the existing state-of-the-art devices, in new spectral engineering and thermal management schemes that radically narrow the efficiency gap between solar thermoelectric generators and conventional photovoltaic panels through novel black metal technology and photovoltaic laser processing techniques.
Revolutionary breakthrough addresses efficiency limitations
Technology Networks has established that solar thermoelectric generators (STEGs) have been studied as a potential source of solar electricity generation. STEGs have the advantage of being able to utilize any form of thermal energy as well as sunlight, unlike the photovoltaics presently employed in the majority of solar panels. The basic devices contain hot and cold surfaces and are filled with semiconductor materials, and the temperature difference between the surfaces produces electricity using the Seebeck effect.
However, the modern STEGs still have significant efficiency shortcomings that do not allow them to be more extensively used in the form of a practical energy source. Currently, the majority of solar thermoelectric generators can turn less than 1 percent of sunshine into electricity, about 20 percent of which is the case with solar panels installed in homes.
New methods developed by scientists at the University of Rochester in the Institute of Optics cut that efficiency gap drastically. The team reported their studied approach to spectral engineering and thermal management in a publication in Light: Science and Applications, generating 15 times more power as compared to the predecessor devices.
Black metal technology increases energy absorption
Researchers have been working on enhancing the semiconductor materials in STEGs over the past decades and have yielded small improvements in overall efficiency, says Chunlei Guo, a professor of optics and physics. In this work, we do not even touch the semiconductor material, but rather we looked at the hot and the cold side of the apparatus.
Three strategies were developed in the new, high-efficiency STEGs. To begin with, the researchers employed a special black metal technology invented in the laboratory of Guo to convert ordinary tungsten into a selective light absorber at the solar frequencies on the hot side of the STEG. They produced nanoscale structures on metal surfaces with the help of powerful pulses of the femtosecond laser and improved the energy absorption of the material by sunlight.
Greenhouse effect and cooling optimization
Second, the researchers placed a piece of plastic covering the black metal to form a mini greenhouse, similar to one in a farm, says Guo. You can reduce convection and conduction and allow more heat to be trapped, raising the temperature on the hot side. This method minimizes heat loss at other wavelengths and eliminates the loss of heat.
High heat dissipation finishes the system
Finally, on the cold face of the STEG, again, they applied the femtosecond bursts of laser to regular aluminum and, in effect, they fashioned a heat sink with miniature structures that enhanced the heat release in both radiation and convection. That action doubles the cooling capacity of a normal aluminum heat dissipator, generating the best temperature difference throughout the equipment.
Guo and his research team in the study gave a simple demonstration of how their STEGS can be applied in powering LEDs far better than the existing approaches. Guo notes that the technology might also be available to power wireless sensors for the Internet of Things, drive wearable devices, or act as off-grid renewable energy systems in rural locations.
The breakthrough of the solar thermoelectric generator efficiency of the University of Rochester is a paradigm shift towards not improving semiconductor, but maximising thermal management systems, and that innovative surface engineering and laser processing can significantly improve the functionality of renewable energy technology and provide new opportunities in the use of distributed power generation.