Project Profile: Low-Cost Self-Cleaning Reflector Coatings for CSP Collectors

-- This project is inactive --

The Oak Ridge National Laboratory (ORNL), under the National Laboratory R&D competitive funding opportunity, developed self-cleaning, optically transparent coatings that can be applied to the surfaces of heliostats and collector mirrors in concentrating solar power (CSP) systems. The coatings can help to achieve the SunShot Initiative cost goals by reducing the time and costs associated with cleaning collector and heliostat mirror surfaces and increasing the reliability and efficiency of CSP systems.

Approach

The research team has developed optically transparent superhydrophobic (SH) materials and coatings based on nanostructured silica surfaces that can address the soiling and maintenance issues of CSP systems. In this project, the team investigated and optimized the adhesion, transmittance, and water and dirt repellent properties of these multifunctional nanostructured surface coatings. The team worked to improve the technology using a suspension of SH silica nanoparticles, polymeric binders, and solvents that can be applied to large area surfaces using simple low-cost spray coating techniques developed by the commercial paint industry.

Innovation

This project derived innovative new coatings by modifying high surface-area nano-structured silica particles with self-assembled low surface energy monolayers. The coatings are transparent over the entire ultraviolet-visible near-infrared range and are applicable to surfaces other than glass, making them suitable for other retrofitting and refinishing applications.

Conclusions

The work performed during the course of this project on the development of durable, optically transparent anti-soiling coatings has led to considerable performance improvements in both the durability and optical transparency of the coatings in comparison with our best performing optically transparent coatings at the beginning of the project. Specifically, the mechanical durability of the coatings has shown a 30 fold improvement, while the optical transparency of the coatings has improved by 1-2% over the wavelength range 250nm to 600nm, in comparison with the original anti-soiling coatings. Accelerated UV environmental testing of the anti-soiling coatings developed in this project show no degradation in hydrophobicity or optical transparency of the coatings over a simulated exposure period of 2-5years. Test mirrors, coated with the anti-soiling coatings developed in this project, are now under test at the Ivanpah CSP facility in the Mojave Desert, CA in collaboration with BrightSource Energy and NRG Energy.

Publications, Patents, and Awards

• Polizos, Georgios, et al. "Scalable superhydrophobic coatings based on fluorinated diatomaceous earth: Abrasion resistance versus particle geometry." Applied Surface Science 292 (2014): 563-569. doi: 10.1016/j.apsusc.2013.12.009
• Boreyko, Jonathan B., et al. "Air-stable droplet interface bilayers on oil-infused surfaces." Proceedings of the National Academy of Sciences 111.21 (2014): 7588-7593. doi:10.1073/pnas.1400381111/-/DCSupplemental.
• Conference Proceeding: Schaeffer, D. A., et al. "Large Area Transparent Superhydrophobic Coatings." Future of Instrumentation International Workshop IEEE. 2013.
• Patent: Simpson, John T., Georgios Polyzos, and Daniel A. Schaeffer. "Durable superhydrophobic coatings." U.S. Patent Application No. 13/793,394. 

 

Learn about other DOE competitive awards for concentrating solar power research that are in progress.