Experimental demonstration of a 5 kWth granular-flow reactor for solar thermochemical energy storage with aluminum-doped calcium manganite particles

Using concentrated solar energy as the source of high-temperature process heat, a two-step CO2 splitting thermochemical cycle based on Zn/ZnO redox reactions is applied to produce renewable carbon-neutral fuels. The solar thermochemical cycle consists of: 1) the solar endothermic dissociation of ZnO to Zn and O2; 2) the non-solar exothermic reduction of CO2 with Zn to CO and ZnO; the latter is the recycled to the 1st solar step. The net reaction is CO2 = CO + 1/2 O2, with products formed in different steps, thereby eliminating the need for their separation. A Second-Law thermodynamic analysis indicates a maximum solar-to-chemical energy conversion efficiency of 39% for a solar concentration ratio of 5000 suns. The technical feasibility of the first step of the cycle has been demonstrated in a high-flux solar furnace with a 10 kW solar reactor prototype. The second step of the cycle is experimentally investigated in a hot-wall quartz aerosol flow reactor, designed for in-situ quenching of Zn(g), formation of Zn nanoparticles, and oxidation with CO2. The effect of varying the molar flow ratios of the reactants was investigated. Chemical conversions were determined by gas chromatography and X-ray diffraction. Chemical conversions of Zn to ZnO of up to 88% were obtained for a residence time of ∼ 3.05 s. For all of the experiments, the reactions primarily occurred outside the aerosol jet flow on the surfaces of the reaction zone.

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Revisiting the BaO2/BaO redox cycle for solar thermochemical energy storage

Physical Chemistry Chemical Physics ◽

10.1039/c5cp07777j ◽

2016 ◽

Vol 18 (11) ◽

pp. 8039-8048 ◽

Cited By ~ 38

Author(s):

A. J. Carrillo ◽

D. Sastre ◽

D. P. Serrano ◽

P. Pizarro ◽

J. M. Coronado

Keyword(s):

Energy Storage ◽

Storage System ◽

Energy Storage System ◽

Redox Cycle ◽

System P ◽

Barium Peroxide ◽

Solar Thermochemical

The barium peroxide-based redox cycle, proposed in the late 1970s, was re-evaluated as a thermochemical energy storage system.

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Ammonia synthesis for producing supercritical steam in the context of solar thermochemical energy storage

10.1063/1.4949108 ◽

2016 ◽

Cited By ~ 9

Author(s):

Chen Chen ◽

Hamarz Aryafar ◽

Gopinath Warrier ◽

Keith M. Lovegrove ◽

Adrienne S. Lavine

Keyword(s):

Energy Storage ◽

Ammonia Synthesis ◽

Solar Thermochemical

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Efficiency Enhancement of an Ammonia-Based Solar Thermochemical Energy Storage System Implemented with Hydrogen Permeation Membrane

Sustainability ◽

10.3390/su132212783 ◽

2021 ◽

Vol 13 (22) ◽

pp. 12783

Author(s):

Qi Xia ◽

Shuaiming Feng ◽

Mingmin Kong ◽

Chen Chen

Keyword(s):

Energy Storage ◽

Reaction Temperature ◽

Hydrogen Permeation ◽

Storage System ◽

Energy Storage System ◽

Ammonia Decomposition ◽

Exergy Loss ◽

Parabolic Trough ◽

Solar Thermochemical ◽

Exergy Losses

The ammonia-based solar thermochemical energy storage (TCES) is one of the most promising solar TCESs. However, the solar-to-electric efficiency is still not high enough for further commercialization. The efficiency is limited by the high ammonia decomposition reaction temperature, which does not only increase the exergy loss through the heat recuperation but also causes a large re-radiation loss. Nonetheless, lowering the reaction temperature would impact the conversion and the energy storage capacity. Thanks to the recent development of the membrane technology, the hydrogen permeation membrane has the potential to enhance the conversion of ammonia decomposition under the moderate operating temperature. In this paper, an ammonia-based solar thermochemical energy storage system implemented with hydrogen permeation membrane is proposed for the first time. The system model has been developed using the Aspen Plus software implemented with user-defined Fortran subroutines. The model is validated by comparing model-generated reactor temperatures and conversions profiles with data from references. With the validated model, an exergy analysis is performed to investigate the main exergy losses of the system. Furthermore, the effects of the membrane on system efficiency improvement are studied. The results show that exergy loss in the charging loop is dominant, among which the exergy losses of Heat Exchanger Eh,A, together with that of the re-radiation Er, play important roles. Compared with the conventional system, i.e., the system without the membrane, the Eh,A and Er of the proposed system are more than 30% lower because the hydrogen permeation membrane can improve ammonia conversion at a lower endothermic reaction outlet temperature. Consequently, the proposed system, presumably realized by the parabolic trough collector at ~400 °C, has a theoretical solar-to-electric efficiency of ηste, which is 4.4% higher than the conventional ammonia-based solar thermochemical energy storage system. Last but not least, the efficiency is 3.7% higher than that of a typical parabolic trough solar power plant, which verifies the thermodynamic feasibility of further commercialization.

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