Metal hydrides for concentrating solar thermal power energy storage

Abstract

The development of alternative methods for thermal energy storage is important for improving the efficiency and decreasing the cost for Concentrating Solarthermal Power (CSP). We focus on the underlying technology that allows metal hydrides to function as Thermal Energy Storage (TES) systems and highlight the current state-of-the-art materials that can operate at temperatures as low as room-temperature and as high as 1100 o C. The potential of metal hydrides for thermal storage is explored while current knowledge gaps about hydride properties, such as hydride thermodynamics, intrinsic kinetics and cyclic stability, are identified. The engineering challenges associated with utilising metal hydrides for high-temperature thermal energy storage are also addressed.

Rare Earth Borohydrides—Crystal Structures and Thermal Properties

“…Above 450 • C, new peaks emerge and gain intensity up to the maximum temperature of 600 • C. They can be assigned to CeD 2 , and have been highlighted in Figure 10b. The formation of cerium borides such as CeB 4 or CeB 6 could not be observed under the applied experimental conditions. Ley et al performed in situ SR-PXD studies with a high heating rate of 8 • C/min up to 500 • C on several nLiBH 4 -CeCl 3 mixtures (n = 3, 4) [8].…”

“…Metal borohydrides are being intensively studied as potential hydrogen and thermal energy storage materials [1][2][3][4][5][6][7] as well as solid state electrolytes [8][9][10][11]. Alkali and alkaline earth borohydrides such as LiBH 4 and Mg(BH 4 ) 2 are of great interest due to their high gravimetric hydrogen storage capacity.…”

Complex Metal Hydrides for Hydrogen, Thermal and Electrochemical Energy Storage

“…This is because the thermochemical heat storage capacity of metal hydrides can exceed the sensible heat storage capacity of molten salts by a factor of >10 [216]. In fact, the theoretical thermochemical heat storage capacity of some metal hydrides, such as LiH and CaH 2 , are only exceeded by methane reforming reactions [214,218]. Specific details about the energy cycle for using metal hydrides as high temperature heat storage materials for CSP can be found elsewhere [67,214,[219][220][221][222].…”

“…In fact, the theoretical thermochemical heat storage capacity of some metal hydrides, such as LiH and CaH 2 , are only exceeded by methane reforming reactions [214,218]. Specific details about the energy cycle for using metal hydrides as high temperature heat storage materials for CSP can be found elsewhere [67,214,[219][220][221][222]. Besides the intermetallic hydrides first considered for heat storage in the 1970s and 1980s, most of the research on metal hydrides for high temperature heat storage (T > 400 • C) has focused on a few particular sub-sets.…”

“…With the commercialization of concentrating solar power plants (CSPs) incorporating molten nitrate salts heat storage and, in conjunction with the U.S. Department of Energy SunShot Initiative to drive down the cost of solar electricity [212], there has been a renewed focus on the potential of low-cost, high-temperature metal hydrides to be the second generation of CSP heat storage materials that can operate at temperatures above 600 • C [213][214][215][216][217]. This is because the thermochemical heat storage capacity of metal hydrides can exceed the sensible heat storage capacity of molten salts by a factor of >10 [216].…”