Techno-economic analysis of solar thermal power plants using liquid sodium as heat transfer fluid

Abstract

Solar thermal power plants with central receiver and thermal storage are expected to be one key technology in future electricity generation, because they are renewable and due to the thermal storage independent of the current solar radiation. State-of-the-art solar power plants often use molten nitrate salts as heat transfer fluid. The use of liquid sodium instead leads to lower electricity generation costs. Sodium has a high thermal conductivity and thus large heat transfer rates are possible. Hence, a smaller absorber surface is sufficient for the same thermal power. As a result, the sodium receiver achieves a higher efficiency at lower investment cost. Additionally, the aiming strategy, which reduces the peak heat flux on molten salt receivers isn't necessary for sodium. Even at high heat flux densities, the absorber tubes will be cooled sufficiently due to the high heat transfer coefficients. Therefore, the sodium receiver in this analysis is designed for one single aim point, resulting in a heat flux density of q 1.06 MW/m mean 2 = and q 2.99 MW/m peak 2 =. The state-of-the-art system with molten salt considers q 0.51 MW/m mean 2 = and q 1.0 MW/m peak 2 =. The presented techno-economic analysis of two sodium based concepts compared to a reference system with molten salt results in up to 16% lower electricity generation costs.

Storage plants – a solution to the residual load challenge of the power sector?

“…3. Thermal energy storage consisting of two tanks that contain molten nitrate salts just like those used in solar thermal power plants [Fritsch et al 2019], [Turchi 2019]. Heat is stored when pumping salt from a cold tank (≈280°C) to a hot tank (≈560°C) while heating it up with one of the below mentioned alternatives.…”

Concentrated Solar Power Plants with Molten Salt Storage: Economic Aspects and Perspectives in the European Union

“…The technology was developed in the 90s by the Sandia National Laboratories [18]. Molten salt is more economically viable than other HTFs, such as mineral oil [19,20].…”

Comparison of Li2CO3-Na2CO3-K2CO3, KCl-MgCl2 and NaNO3-KNO3 as heat transfer fluid for different sCO2 and steam power cycles in CSP tower plant under different DNI conditions

“…27,28 Receivers having liquid HTF include high-temperature salts like halide (chloride and fluoride) and carbonate salts and some liquid metals (lead, bismuth and sodium). [29][30][31] The HTF is an important part of the transfer and storage of thermal energy in a centralized solar system. Due to its thermo-physical nature, the salt mixture can be used as a high-temperature HTF.…”