Heat Modeling and Material Development of Mg-Based Nanomaterials Combined with Solid Oxide Fuel Cell for Stationary Energy Storage

Abstract

Mg-based materials have been investigated as hydrogen storage materials, especially for possible onboard storage in fuel cell vehicles for decades. Recently, with the development of large-scale fuel cell technologies, the development of Mg-based materials as stationary storage to supply hydrogen to fuel-cell components and provide electricity and heat is becoming increasingly promising. In this work, numerical analysis of heat balance management for stationary solid oxide fuel cell (SOFC) systems combined with MgH 2 materials based on a carbon-neutral design concept was performed. Waste heat from the SOFC is supplied to hydrogen desorption as endothermic heat for the MgH 2 materials. The net efficiency of this model achieves 82% lower heating value (LHV), and the efficiency of electrical power output becomes 68.6% in minimizing heat output per total energy output when all available heat of waste gas and system is supplied to warm up the storage. For the development of Mg-based hydrogen storage materials, various nano-processing techniques have been widely applied to synthesize Mg-based materials with small particle and crystallite sizes, resulting in good hydrogen storage kinetics, but poor thermal conductivity. Here, three kinds of Mg-based materials were investigated and compared: 325 mesh Mg powers, 300 nm Mg nanoparticles synthesized by hydrogen plasma metal reaction, and Mg 50 Co 50 metastable alloy with body-centered cubic structure. Based on the overall performances of hydrogen capacity, absorption kinetics and thermal conductivity of the materials, the Mg nanoparticle sample by plasma synthesis is the most promising material for this potential application. The findings in this paper may shed light on a new energy conversion and utilization technology on MgH 2-SOFC combined concept.

Catalysis and Downsizing in Mg-Based Hydrogen Storage Materials

“…Emerging ideas, such as new composite materials, metastable alloys, geometrical storage materials, as well as nano-confinement technology, may give us some new directions to develop Mg-based hydrogen storage materials in the future. On the other hand, Mg-based nanomaterials combined with solid oxide fuel cells for stationary energy storage have been proposed, and this makes it possible to apply Mg-based hydrogen storage materials to large-scale storage with a working temperature for storage materials higher than 250 • C [43]. In this case, thermodynamic change is no longer a problem.…”

“…It is reported that reducing the size of hydrogen storage materials could lead to a remarkable change in hydrogen absorption/desorption kinetics [12,[38][39][40][41]. It is well proven that small particles of hydrides have an influence on hydrogen absorption/desorption kinetic properties, mainly due to shortened hydrogen diffusion and dissociation pathways, and enlarged surface free energy when the size decreases to below a few nanometers [42,43]. Numerous methods are applied to synthesize the hydrogen storage nanostructured materials, including ball milling, the hydrogen plasma metal reaction, nano-confinement, thin film synthesis, and catalyzed solution synthesis.…”

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

“…In the hydrogen storage area, Mg-based materials are promising candidates due to the large abundant reserve in the crust, the light weight of Mg element, and high hydrogen storage capacity (7.6 wt % for Mg) [34][35][36]. However, the relatively higher hydrogen desorption enthalpy (74.6 kJ/mol, from Sandia National Lab database) becomes a restriction for the future application of Mg-based materials for hydrogen storage [35,37,38]. The story is totally different when Mg-based materials are applied to TES.…”

Effect of Yttrium on antioxidant process of Mg‐Ni‐Zn phase change thermal storage alloys

“…In TES systems, Mg‐based phase change heat storage alloy has the advantage of low corrosion at high temperatures, which are better than Al‐based alloys in comparison. Currently, researchers have focused more on the Mg‐based phase change heat storage alloy as TES materials, and have conducted a lot of research 19‐24 . For instance, Faik et al 25 investigated the structure and thermophysical properties of Zn 85.8 Al 8.2 Mg 6 and Mg 70 Zn 24.9 Al 5.1 eutectic alloys, and found that the great potential of the alloys studied in heat energy storage applications.…”

“…Currently, researchers have focused more on the Mg-based phase change heat storage alloy as TES materials, and have conducted a lot of research. [19][20][21][22][23][24] For instance, Faik et al 25 investigated the structure and thermophysical properties of Zn 85.8 Al 8.2 Mg 6 and Mg 70 Zn 24.9 Al 5.1 eutectic alloys, and found that the great potential of the alloys studied in heat energy storage applications. Fang et al 26 calculated Mg-Bi phase change alloy as TES material and found that Mg-54%Bi alloy has high melting enthalpy and activation energy, among which the activation energy is as high as 1322.8 kJÁmol −1 .…”