Session: 06-03: CSP Receivers and Reactors II

Paper Number: 164854

164854 - Efficient Generation of Solar Heat Up to 800°c Enabled by Curved Silica-Alumina Aerogels 

Abstract: 

The use of linear concentrating systems for generating solar industrial process heat and baseload electricity is an attractive prospect owing to their high optical efficiency and reduced capital costs when compared to solar towers. However, linear concentrators face challenges related to low solar-to-thermal conversion at high operating temperatures due to their significant thermal losses. Degradation of efficient selective absorber coatings limits their use to below 600°C, while operating under vacuum introduces additional cost. To address this issue, silica aerogels can be integrated into the design of the linear receiver to improve the performance of parabolic trough collectors (PTC). It is possible to use broadband absorbers while leveraging the greenhouse effect of silica aerogels to suppress the emitted radiation, thereby enhancing the receiver selectivity.

In previous work, we characterized the optical and thermal properties of large area alumina-coated silica aerogels. This demonstrated the potential for record-high solar receiver efficiencies in high-temperature environments ranging from 550 to 800°C.¹ The alumina coating, achieved through a single cycle of atomic layer deposition (ALD), is necessary to mitigate the densification experienced by silica aerogels at these elevated temperatures.²

In this study, we developed and constructed a prototype solar receiver using novel curved aerogel tiles. We evaluated the performance of the module and assessed the economic feasibility of this technology through experimental heat loss testing. Heat loss testing at temperatures up to 800°C showed that the new system reduced heat losses by more than half compared to an absorber tube without aerogels. The results suggest that the proposed receiver requires substantially less input power and can operate efficiently at low vacuum and ambient pressure, with heat losses under 2.3 kW/m when operating at ambient pressure. Furthermore, we performed a long-term annealing study to demonstrate the remarkable thermal stability of this material over an extended period of time, highlighting its potential for a long service life.

We subsequently estimated annualized plant efficiencies and heat costs for aerogel-based receivers operating between 600°C and 800°C across different locations with varying amounts of solar irradiance. Our calculations yielded promising results, particularly in regions with high solar irradiance, like the Southwestern U.S. and Chile. In these areas, we observed good receiver efficiencies of approximately 80% and heat cost estimates of less than 4 cents/kWh-th.

References

1.        Berquist, Z. J. et al. Large area transparent refractory aerogels with high solar thermal performance. Solar Energy 292, 113437 (2025).

2.        Gayle, A. J. et al. Tunable Atomic Layer Deposition into Ultra-High-Aspect-Ratio (>60000:1) Aerogel Monoliths Enabled by Transport Modeling. Chemistry of Materials 33, 5572–5583 (2021).

Presenting Author: Andres Miranda Manon University of Michigan

Presenting Author Biography: 4th year Chemical Engineering PhD Student at the University of Michigan