Recent Advancements in CSP: Evaluating High-Temperature Heat Transfer Fluids, Corrosion Prevention, and Alloy Selection for Enhanced Energy Density

Abstract

Remarkable progress has been made in harnessing solar energy for electricity generation through Concentrated Solar Power (CSP) plants, which now exceed 6 GW in global installed capacity. The utilization of high-temperature heat transfer fluids (HTFs) has significantly improved system efficiencies; for instance, nitrate-based molten salts commonly operate at 300–565 °C, while newer chloride and carbonate salts can reach 700-800 °C enabling advanced supercritical CO₂ cycles with potential thermal-to-electric efficiencies of up to 50%. However, salts often cost $0.2-2.5 per kg and require carefully selected corrosion-resistant alloys. Meanwhile, liquid metals such as lead-bismuth can handle temperatures above 800 °C, offering high volumetric energy densities (often >20,000 MJ/m³) and strong heat-transfer properties. Yet, they demand rigorous corrosion mitigation and elevated capital expenditures. This paper provides an in-depth review of HTF selection, corrosion prevention strategies, material costs, and energy density aspects in CSP. It further examines the feasibility of liquid metals relative to molten salts, covering suitable alloy materials for storage. By highlighting practical performance data and cost considerations, this review offers key insights into advancements and challenges of CSP technology ultimately proposing pathways toward more efficient, high-temperature solar energy generation.