Coffee-based colloids for direct solar absorption
(PHYSorg.com Physics)

Solar energy is one of the most promising resources to help reduce fossil fuel consumption and mitigate greenhouse gas emissions to power a sustainable future. Devices presently in use to convert solar energy into thermal energy mostly rely on the indirect absorption of sunlight, where the efficiency is generally limited as a result of major convective heat losses into the surrounding environment. A promising alternative is the direct absorption of sunlight, where a fluid can serve as both solar energy absorber and heat carrier. The advantage of the technique is based on reduced convective and radiative heat losses, since temperature peak shifts from the absorbent surface (indirect absorption) to the bulk region of the carrier fluid (direct absorption). In a recent study, Matteo Alberghini and co-workers at the Departments of Energy, Applied Science and Technology, and the National Institute of Optics in Italy, investigated a sustainable, stable and inexpensive colloid based on coffee solutions to implement direct solar absorption. Results of their work are now published on Scientific Reports.