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In order to uncover the inner working mechanism and performance of solid oxide fuel cell (SOFC) with biomass gasification syngas as fuel, a two dimensional SOFC multi-physical field model is established. This study makes up for the deficiency that the previous studies of coupling biomass gasification unit and SOFC stack mostly stay at the system level. The results show that the SOFC fueled by the syngas produced from gasification of biomass with steam as the agent has the best performance. The peak power density could achieve approximately 10240 W m−2. With the improvement of operating temperature, the peak power density of SOFC will be increased. At the temperature of 1123 K, the peak power density could achieve about 15128 W m−2. The average reaction rate of water gas shift (WGS) reaction is −29.73 mol m−3 s−1 when the operating temperature is 1123 K. This indicates that the WGS reaction will proceed in reverse direction at high temperatures, thereby reducing the hydrogen concentration. In addition, increase in the anode flux and decrease in the cell length lead to the increase of SOFC current density. In general, this work could provide guidance for the optimization and practical application of SOFC using biomass syngas as fuel.

Mg-based materials have become the cornerstone of hydrogen storage applications and have shown recently promises in thermal energy storage applications. However, synthesis of some materials including Mg2FeH6 ternary hydride poses a number of challenges. In spite a variety of reports on various synthesis routes yielding Mg2FeH6, none of them produces a 100% pure Mg2FeH6. In this communication, we have attempted to synthesize Mg2FeH6 by high energy reactive ball milling (HERBM) performed in hydrogen gas. Prior to the ball milling, the starting stoichiometric 2:1 mixture of the initial materials Mg+Fe was heat treated through a judicious temperature program. It was found that the yield of Mg2FeH6 is related to the conditions of heat treatment, time and temperature, and the milling parameters such as ball to powder mass ratio (BPR) and rotation speed of the planetary mill. Moreover, it was found that the synthesis took place in less than 5 hours of milling with a maximum yield of Mg2FeH6 of 84 wt%, which is a noticeable improvement as compared to the reference data.

Thermo-chemical energy storage based on metal hydrides has gained tremendous interest in solar heat storage applications such as concentrated solar power systems (CSP) and parabolic troughs. In such systems, two metal hydride beds are connected and operating in an alternative way as energy storage or hydrogen storage. However, the selection of metal hydrides is essential for a smooth operation of these CSP systems in terms of energy storage efficiency and density. In this study, thermal energy storage systems using metal hydrides are modeled and analyzed in detail using first law of thermodynamics. For these purpose, four conventional metal hydrides are selected namely LaNi5, Mg, Mg2Ni and Mg2FeH6. The comparison of performance is made in terms of volumetric energy storage and energy storage efficiency. The effects of operating conditions (temperature, hydrogen pressure and heat transfer fluid mass flow rates) and reactor design on the aforementioned performance metrics are studied and discussed in detail. The preliminary results showed that Mg-based hydrides store energy ranging from 1.3 to 2.4 GJ m−3 while the energy storage can be as low as 30% due to their slow intrinsic kinetics. On the other hand, coupling Mg-based hydrides with LaNi5 allow us to recover heat at a useful temperature above 330 K with low energy density ca.500 MJ m−3 provided suitable operating conditions are selected. The results of this study will be helpful to screen out all potentially viable hydrides materials for heat storage applications.