Enhancement of fast CO2 capture by a nano-SiO2/CaO composite at Ca-looping conditions

In this paper we show the performance of a new CO(2) sorbent consisting of a dry physical mixture of a Ca-based sorbent and a SiO(2) nanostructured powder. Thermo-gravimetric analysis (TGA) performed at conditions close to the Ca-looping process demonstrate that the rate of CO(2) capture by the mixture is enhanced during the fast carbonation stage of practical interest in applications. Moreover, the residual capture capacity of the mixture is increased. SEM/EDX, physisorption, and XRD analyses indicate that there is a relevant interaction between the nanostructured SiO(2) skeleton and CaO at high temperatures, which serves to improve the efficiency of the transfer of CO(2) to small reactive pores as well as the stability of the sorbent pore structure.     

Modeling,simulation and experimental set-up of a renewable hydrogen-based domestic microgrid

This paper deals with domestic microgrid modeling and simulation covering some aspects not fully addressed in the existing literature. Specifically, most of the reviewed generic models are suitable for long-term simulations but only considering steady-state and nominal operating conditions, which overestimate the energy outputs, hydrogen production and system performance. More specific models are capable of capturing the accurate dynamics of each individual piece of equipment. However, their complexity leads to a high computational burden making it difficult to implement an overall system-scope model including all the interconnected equipment for long-term calculations. This paper seeks to rectify the problem presented by the detected lack of medium-complexity dynamic models of renewable systems with intermediate storage, proposing a domestic microgrid solution composed of photovoltaics, metal hydride hydrogen-based storage with an electrolyzer, polymeric electrolyte fuel cell (PEM-FC), and interconnections with neighbor grids and electric vehicles. This model is validated with experimental data gathered from a pilot microgrid plant designed, built and operated by the authors, and matching simulated data closely.     

Simultaneous production of H2 and C2 hydrocarbons by using a novel configuration solid-electrolyte + fixed bed reactor

A novel combined single chamber solid electrolyte plus fixed bed reactor configuration was developed for the simultaneous production of H₂ and C₂ hydrocarbons from a humidified CH₄ atmosphere. Hence, a Pt/YSZ/Ag solid electrolyte cell was placed on the top of an active oxidative coupling catalyst powder bed Ce–Na₂WO₄/SiO₂. H₂ was produced via steam electrolysis in a Pt cathode of the solid electrolyte cell (H₂O + 2e⁻ → H₂ + O²⁻). Simultaneously, the produced O²⁻ ions were electrochemically pumped to the Ag anode, leading to the C_2s production, via oxidative coupling of CH₄ (4CH₄ + 3O²⁻ → C₂H₄ + C₂H₆ + 3H₂O + 6e⁻). Additionally, non-reacted O²⁻ molecules desorbed to the gas phase (2O²⁻ → O₂+4e⁻) and reacted with CH₄ in the catalyst bed leading to an increase of C_2s yield. The influence of different reaction parameters was investigated together with long-term reaction experiments, confirming the stability of this configuration for its practical application. The obtained results demonstrated that the addition of an active catalyst bed strongly enhances both: the efficiency of the single chamber steam electrolysis and the oxidative coupling process.