Characterization of solid particle candidates for application in thermal energy storage and concentrating solar power systems

Journal Article · 04 August 2023 · Solar Energy

DOI: https://doi.org/10.1016/j.solener.2023.111908 · OSTI ID:1996222

Davenport, Patrick  ^[1]; Ma, Zhiwen  ^[1]; Schirck, Jason  ^[2]; Nation, William ^[2]; Morris, Aaron  ^[2]; Wang, Xingchao  ^[3]; Lambert, Matthew ^[4]

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1. National Renewable Energy Laboratory (NREL), Golden, CO (United States)
2. Purdue Univ., West Lafayette, IN (United States)
3. National Renewable Energy Laboratory (NREL), Golden, CO (United States); Colorado School of Mines, Golden, CO (United States)
4. Allied Mineral Products, Columbus, OH (United States)

Thermal energy storage (TES) enables concentrating solar power to remain competitive in the renewable energy mix by firming up intermittent solar resource and providing grid services such as load shifting. Free from siting constraints, stand-alone TES systems show promise as a low-cost alternative to traditional pumped-storage hydropower or compressed air energy storage. At the core of all TES technologies is a storage medium, the selection of which governs many aspects of system design and operation. Although the majority of commercial installations utilize molten salts, solid particles can demonstrate stability over wider temperature ranges. This amounts to increased energy storage densities and corresponding reductions in system cost which is essential in achieving low-cost energy storage. In this work, eight solid particle candidates are systematically identified and screened for application in a specific particle-TES system. The five most promising candidates (CARBO CP and HSP, calcined flint clay (CFC), brown fused alumina (BFA), and silica sand) are further characterized by size and morphology for fluidization suitability, flowability for particle transport, and thermal stability. Calcined flint clay and brown fused alumina are eventually down-selected due to thermal instability at the target operational temperature of 1200 °C. Although the physical characteristics of CARBO outperform silica sand in all categories examined, the marginal performance gains are considered insufficient to justify the additional media cost so silica sand is selected as the leading candidate. Within the silica sand (α-quartz) space, the high end of Geldart Group B particles is identified to satisfy the target fluidization regime for the application of interest without compromising particle flowability. Here, in focused testing, Silica 460 is shown to exhibit sufficient stability through long-duration (500-hour) thermal and cyclic testing (1200 °C), 10-hour testing at 1400 °C, and in contact with candidate refractory containment materials. Finally, an average heat capacity of 1.1 J/g∙ °C is measured over 300-1200 °C with a quartz inversion enthalpy (ΔH_α-β) of 10.7J/g.

• Research Organization: National Renewable Energy Laboratory (NREL), Golden, CO (United States)
• Sponsoring Organization: USDOE Advanced Research Projects Agency - Energy (ARPA-E)
• Grant/Contract Number: AC36-08GO28308
• OSTI ID: 1996222
• Report Number(s): NREL/JA-5700-83167; MainId:83940; UUID:f6085671-b267-4d57-8107-3daf2a18a6ab; MainAdminID:70093
• Journal Information: Solar Energy, Journal Name: Solar Energy Vol. 262; ISSN 0038-092X
• Publisher: ElsevierCopyright Statement
• Country of Publication: United States
• Language: English