Comparative techno-thermal analysis of a parabolic trough power plant with thermocline storage: Multi-climatic simulations in Morocco using different heat transfer fluids

Over the past decades, interest has grown in alternative and sustainable ways of generating heat and electricity, focusing on technologies such as Concentrated Solar Power (CSP) with integrated Thermal Energy Storage (TES). This study presents a parabolic trough (PT) power plant model using the TRNSYS simulation software with a cost-effective single-tank TES system. Applying it to a Moroccan case study, the model evaluates thermal performance in various climatic zones using five different heat transfer fluids (HTFs) and storage media. Comparison was undertaken to determine the optimal HTF/medium storage for each zone and propose an economic alternative to the conventional two-tank TES system. These alternatives employ solar salt mixtures (Binary molten salts, Hitec, and Hitec XL) as HTF or storage medium in place of traditional thermal oils (Therminol VP1 and Dowtherm A). Simulation results show that although thermal oils record slightly superior maximum annual SF thermal efficiencies (38.87% for Therminol VP1) compared to solar salts (36.95%–37.35%), the latter, particularly Hitec and Hitec XL, offer considerable cost advantages, with thermal storage costs of 19.86 and 13.24 $/ MWh th respectively, versus 73.50 $/ MWh th for Therminol VP1. Dowtherm A emerges as a more economical oil-based alternative to Therminol VP1. The thermal LCOE remains nearly identical across all configurations (2.25–2.34 c$/ kWh th ), with a total CAPEX ranging from 171.34 to 177.27 M$. These findings confirm that Hitec and Hitec XL present the most cost-effective storage solution with an appreciable performance compromise. The proposed simulation model is fully transferable and can be applied to CSP plant performance assessment in different locations worldwide, requiring only an update of the meteorological input data.