Solar Hydrogen Production via a Samarium Oxide-Based Thermochemical Water Splitting Cycle

Abstract

Abstract:The computational thermodynamic analysis of a samarium oxide-based two-step solar thermochemical water splitting cycle is reported. The analysis is performed using HSC chemistry software and databases. The first (solar-based) step drives the thermal reduction of Sm 2 O 3 into Sm and O 2 . The second (non-solar) step corresponds to the production of H 2 via a water splitting reaction and the oxidation of Sm to Sm 2 O 3 . The equilibrium thermodynamic compositions related to the thermal reduction and water splitting steps are determined. The effect of oxygen partial pressure in the inert flushing gas on the thermal reduction temperature (T H ) is examined. An analysis based on the second law of thermodynamics is performed to determine the cycle efficiency (η cycle ) and solar-to-fuel energy conversion efficiency (η solar´to´fuel ) attainable with and without heat recuperation. The results indicate that η cycle and η solar´to´fuel both increase with decreasing T H , due to the reduction in oxygen partial pressure in the inert flushing gas. Furthermore, the recuperation of heat for the operation of the cycle significantly improves the solar reactor efficiency. For instance, in the case where T H = 2280 K, η cycle = 24.4% and η solar´to´fuel = 29.5% (without heat recuperation), while η cycle = 31.3% and η solar´to´fuel = 37.8% (with 40% heat recuperation).

Techno-Economic Assessment of Solar Hydrogen Production by Means of Thermo-Chemical Cycles

“…Several materials have been analyzed both theoretically and experimentally [16]. Among them are zinc, iron, tin, terbium oxides, mixed ferrite, ceria, and perovskite [17].…”

Co-precipitation synthesized nanostructured Ce0.9Ln0.05Ag0.05O2−δ materials for solar thermochemical conversion of CO2 into fuels

“…In the first phase, the MO is reduced with the help of concentrated solar power, and in phase 2, the reduced MO is reoxidized again via a CO 2 splitting reaction. Zinc oxide [8,9], tin oxide [10,11], iron oxide [12,13], CeO 2 [14][15][16], doped ceria [17][18][19][20], ferrites [21][22][23][24], perovskites [25][26][27][28], and others [29][30][31][32] have been utilized for the solar thermochemical conversion of H 2 O and CO 2 . Among all these, the phase pure CeO 2 is considered as one of the promising options due to its faster reaction kinetics and better thermal stability.…”

Investigation of Zr‐doped ceria for solar thermochemical valorization of CO 2

“…[1][2][3][4] The effectiveness of this redox cycle depends mainly upon the oxygen storage capacity (OSC) of the metal oxides (MOs). To identify the most suitable MO, multiple volatile [5][6][7][8][9][10][11] and nonvolatile [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] redox materials were examined in previous studies. The findings reported in these investigations indicate that the materials in which ceria has been used as the base redox oxide are the state-of-the-art MOs due to their multiple advantages towards reactivity, kinetics, and thermal stability.…”