Highly efficient solar-thermal energy harvesting
Solar energy is one of the renewable energy resources with hourly incident solar flux on earth surface greater than the global energy consumption in a year. Photo-thermal applications for harvesting solar energy currently suffer from low efficiency and require high concentration of sunlight, which adds complexity and cost to the solar energy harvesting systems.
In solar-thermal systems, high conversion efficiency is in significant demand. Localization of heat is a promising approach to achieve these high efficiencies. The localization of heat leads to locally elevated temperature while minimizing dissipated energy. This localization can be incorporated in all forms of phase-change processes, including evaporation, boiling, condensation, and freezing.
In early research in this field, scientists utilized plasmonic nanoparticles to reach locally elevated temperatures for a broad range of applications. There is a significant unexplored gap in fundamental understanding of this localization. The key challenge for increasing efficiency is the design of material structures for energy conversion. Through heat localization, we developed a material structure leading to solar steam generation at low optical concentration with an efficiency of 85%. This high efficiency is reached by a combination of properties in the developed material structures and supports highly efficient solar-assisted phase-change phenomena.