Hydriding characteristics of NaMgH₂F with preliminary technical and cost evaluation of magnesium-based metal hydride materials for concentrating solar power thermal storage

Abstract

An economic assessment is performed on NaMgH2F and magnesium-based metal hydrides as heat storage materials for concentrating solar thermal power.

Complex and liquid hydrides for energy storage

“…Therefore, fluorine substitution is expected to lead to significant thermodynamic destabilization. However, thermodynamic stabilization is also possible, as seen for NaMgH 2 F [61]. The first complex hydride with fluorine substitution was prepared by hydrogenation of the system NaF-Al, which provided complex hydride Na 3 AlH 6-x F x [62,63] [65].…”

Mg-Based Hydrogen Absorbing Materials for Thermal Energy Storage—A Review

“…The poor cycling stability of Mg/MgH2 above 400 °C could not meet the requirements in practical application due to the sintering of Mg particles and the high hydrogen equilibrium pressure of MgH2 at high temperature. According to this, many studies were developed and focused on increasing the operation temperature of the Mg/MgH2 system [47][48][49]. Tortoza et al synthesized a series of Mg (HxF1−x)2 (x = 1, 0.95, 0.85, 0.70, 0.50, 0) compounds by ball milling and annealing under hydrogen atmosphere [50].…”

Metal hydrides for concentrating solar thermal power energy storage

“…A variation on this system has also been studied to increase its enthalpy for solar thermal applications [12]. Fluorine incorporation in NaMgH3 to form NaMgH2F results in an increase in the H2 absorption enthalpy to −96.8 kJ mol −1 H2.…”

“…Certain alloys are commercially available such as heavily substituted Ti-Mn (Ti0.97Zr0.019V0.439Fe0.097Cr0.045Al0.026Mn1.5) [76], which have favourable properties. Other intermetallics excluded include those based on CaNi3, which show degradation in performance for only a minimal decrease in cost compared to CaNi5 [77,78], and solid solutions of Ti-Cr-V-Fe, which remain expensive even when produced with cheaper forms of vanadium such as ferrovanadium [12,79,80].…”

“…As such, research into using metal hydrides for CSP is beginning to intensify with efforts split between: (1) metal hydrides suitable for use with current power tower technologies that operate in the 550 o C to 650 o C range and; (2) metal hydrides that operate in the 650 o C to 800 o C range that are compatible with the next generation of power tower technology being pursued by the U.S. Department of Energy as part of the SunShot research program [10,11]. This research is directed towards identifying promising metal hydrides, testing their H2 sorption properties, designing tanks and test beds with active heat extraction, and testing the metal hydrides under dynamic conditions [7][8][9][12][13][14][15]. Scale-up testing is required to mimic realistic operating conditions and it is clear that the engineering of the metal hydride tank and heat extraction system will be as critical as the properties of the metal hydride itself [14].…”