Transparent Refractory Aerogels for Efficient Spectral Control in High‐Temperature Solar Power Generation

Abstract

Although spectrally selective materials play a key role in existing and emerging solar thermal technologies, temperature‐related degradation currently limits their use to below 700 °C in vacuum and even lower temperatures in air. Here a solar‐transparent refractory aerogel that offers stable performance up to 800 °C in air is demonstrated, which is significantly greater than its silica counterpart. This improved stability is attributed to the formation of a refractory aluminum silicate phase, which is synthesized using a conformal single cycle of atomic layer deposition within the high‐aspect‐ratio pores of silica aerogels. Based on direct heat loss measurements, the transparent refractory aerogel achieves a receiver efficiency of 75% at 100 suns and an absorber temperature of 700 °C, which is a 5% improvement over the state of the art. Transparent refractory aerogels may find widespread applicability in solar thermal technologies by enabling the use of lower‐cost optical focusing systems and eliminating the need for highly evacuated receivers. In particular, a shift to higher operating temperatures while maintaining a high receiver efficiency can enable the use of advanced supercritical CO2 power cycles and ultimately translate to an ≈10% (absolute) improvement in solar‐to‐electrical conversion efficiency relative to existing linear concentrating systems.

Integrating Structural Colors with Additive Manufacturing Using Atomic Layer Deposition

“…One advantage of structural color layers over traditional polymer-based paints is their improved thermal stability, which arises from the use of entirely inorganic materials. While the constituent materials in this study may not surpass the best pigment-based paints, dielectric materials like Al 2 O 3 are stable up to 800 °C . Furthermore, with the proper choice of materials, the coating can also serve as a “shield” against thermochemical reactions such as oxidation in humid air.…”

Opportunities for mesoporous silica aerogels in parabolic trough collectors

“…For MS, multicomponent mesoporous insulation such as our previous work on developing refractory aerogels offers one possible pathway. 30 MS coated with a single cycle of alumina maintains hydrophilicity of the multicomponent insulation even at temperatures as high as 500°C. The presence of water at high temperatures helps close the infrared transparency gap of MS, leading to reduced radiative losses.…”

“…These densities are much greater than the densities of MS typically designed for transparent insulators (<170 kg/m 3 ), 25,29,30 suggesting that future designs of MS for high temperature operation should use higher densities. Secondly, the optimal density increases with increasing MS thickness.…”

Transparent thermal insulation ceramic aerogel materials for solar thermal conversion

“…Each year, over 627 TW h of energy in the United States is converted from fossil fuel sources to thermal energy, 1 while its environmental impact motivates an alternative pathway towards solar thermal generation. [2][3][4][5][6] Effective thermal management is critical for energy-efficient solar thermal applications, which requires advanced thermal management materials. 2,7,8 In this context, transparent silica aerogel materials show great promise in solar thermal conversion, 3 since they show high solar light transmission and heat loss suppression due to their transparent porous microstructure.…”

“…[2][3][4][5][6] Effective thermal management is critical for energy-efficient solar thermal applications, which requires advanced thermal management materials. 2,7,8 In this context, transparent silica aerogel materials show great promise in solar thermal conversion, 3 since they show high solar light transmission and heat loss suppression due to their transparent porous microstructure. Optical transparency and thermal insulation are two important aspects of solar thermal systems and window materials.…”