Abstract: The irreversible release of the lattice oxygen in layered cathodes is one of the major degradation mechanisms of lithium ion batteries, which accounts for a number of battery failures including the voltage/capacity fade, loss of cation ions and detachment of the primary particles, etc. Oxygen release is generally attributed to the stepwise thermodynamic controlled phase transitions from the layered to spinel and rock salt phases. Here, we report a strong kinetic effect from the mobility of cation ions, whose migration barrier can be significantly modulated by the phase epitaxy at the degrading interface. It ends up with a clear oxygen release heterogeneity and completely different reaction pathways between the thin and thick areas, as well as the interparticle valence boundaries, both of which widely exist in the mainstream cathode design with the secondary agglomerates. This work unveils the origin of the heterogenous oxygen release in the layered cathodes. It also sheds light on the rational design of cathode materials with enhanced oxygen stability by suppressing the cation migration.

Abstract: Despite the recent promising potential of plasma-based nitrogen fixation, the technology faces significant challenges in efficient upscaling. To tackle this challenge, we investigate two reactors, i.e., a small one, operating in a flow rate range of 5-20 ln min-1 and current range of 200-500 mA, and a larger one, operating at higher flow rate (100-300 ln min-1) and current (400-1000 mA). Both reactors operate in a pin-to-pin configuration and are powered by direct current (DC) from the same power supply unit, to allow easy comparison and evaluate the effect of upscaling. In the small reactor, we achieve the lowest energy cost (EC) of 2.8 MJ mol-1, for a NOx concentration of 1.72%, at a flow rate of 20 ln min-1, yielding a production rate (PR) of 33 g h-1. These values are obtained in air; in oxygen-enriched air, the results are typically better, at the cost of producing oxygen-enriched air. In the large reactor, the higher flow rates reduce the NOx concentration due to lower SEI, while maintaining a similar EC. This stresses the important effect of the geometrical configuration of the arc, which is typically concentrated in the center of the reactor, resulting in limited coverage of the reacting gas flow, and this is identified as the limiting factor for upscaling. However, our experiments reveal that by changing the reactor configuration, and thus the plasma geometry and power deposition mechanisms, the amount of gas treated by the plasma can be enhanced, leading to successful upscaling. To obtain more insights in our experiments, we performed thermodynamic equilibrium calculations. First of all, they show that our measured lowest EC closely aligns with the calculated minimum thermodynamic equilibrium at atmospheric pressure. In addition, they reveal that the limited NOx production in the large reactor results from the contracted nature of the plasma. To solve this limitation, we let the large reactor operate in so-called torch configuration. Indeed, the latter enhances the NOx concentrations compared to the pin-to-pin configuration, yielding a PR of 80 g h-1 at an EC of 2.9 MJ mol-1 and NOx concentration of 0.31%. This illustrates the importance of reactor design in upscaling. With the focus on feasibility evaluation of scaling-up plasma-based nitrogen fixation by combined experiments and thermodynamic modelling, we aim to tackle the challenge of design and development of an energy-efficient and scaled-up plasma reactor.

Abstract: A new method is developed for synthesizing Ti4O7 supported Ru@Pt core–shell catalyst (Ru@Pt/Ti4O7) through pyrolysis followed by microwave irradiation. The purpose is to improve the Ru durability of PtRu from core–shell structure and strong bonding to Ti4O7 oxide. In this method, the first step is to co-reduce the mixture of ruthenium precursor and TiO2 in a H2 reducing atmosphere under heat-treatment to obtain a Ru core on Ti4O7 support, and the second step is to create a shell of platinum via microwave irradiation. Energy dispersive X-ray spectrometry, X-ray Diffraction, High-resolution Scanning Transmission Electron Microscopy with the high-angle annular dark-field method and Electron Energy-Loss Spectroscopy are used to demonstrate that this catalyst with larger particles has a core–shell structure with a Ru core and a Pt shell. Electrochemical measurements show Ru@Pt/Ti4O7 catalyst has a higher CO-tolerance capability than that of PtRu/C alloy catalyst.

Abstract: Nickel-containing N-doped carbons were synthesized for the electrochemical reduction of CO2 to CO, which is a promising approach to reduce the atmospheric CO2 levels and its negative impact on the environment. Unfortunately, poor performance (activity, selectivity and/or stability) is still a major hurdle for the economical implementation of this type of materials. The electrocatalysts were prepared through an easily up-scalable and easily tunable method based on the pyrolysis of Ni-containing N-doped carbons. Ni–N–AC–B1 synthesized with a high relative amount of nitrogen and nickel with respect to carbon, was identified as the most promising candidate for this reaction based on its partial CO current density (4.2 mA cm−2), its overpotential (0.57 V) and its faradaic efficiency to CO (>99%). This results in unprecedented values for the current density per g active sites (690 A g−1 active sites). Combined with its decent stability and its high performance in an actual electrolyzer setup, this makes it a promising candidate for the electrochemical reduction of CO2 to CO on a larger scale. Finally, the evaluation of this kind of material in a flow-cell setup has been limited and to the best of our knowledge never included an evaluation of several crucial parameters (e.g. electrolyte type, anode composition and membrane type) and is an essential investigation in the move towards up-scaling and ultimately industrial application of this technique. This study resulted in an optimal cell configuration, consisting of Pt as an anode, Fumatech® as the membrane and 1 M KHCO3 and 2 M KOH as catholyte and anolyte, respectively. In conclusion, this research offers a unique combination of electrocatalyst development and reactor optimization.

Abstract: Winter peaks in Belgian electricity demand are significantly higher than the summer peaks, creating a greater potential for imbalances between demand and supply. This potential is exacerbated because of the risk of outages in its ageing nuclear power plants, which are being phased out in the medium term. This paper conducts a choice experiment to investigate the acceptability of a load control-based demand response program in the winter months. It surveys 186 respondents on their willingness to accept limits on the use of home appliances in return for a compensation. Results indicate that respondents are most affected by the days of the week that their appliance usage would be curtailed, and by the compensation they would receive. The willingness to enroll in a program increases with age, environmental consciousness, home ownership, and lower privacy concerns. The analysis predicts that 95% of the sample surveyed could enroll in a daily load control program for a compen- sation of €41 per household per year. Thus while an initial rollout among older and more pro-environment homeowners could be successful, a wider implementation would require an explanation of its environmental and financial benefits to the population, and a greater consideration of their data privacy concerns.

Abstract: This paper assesses unintentional interference between different public policies promoting energy efficiency and renewable energy. The paper develops a methodology to study the interference by analysing the economic and technical behaviour of a hybrid energy system. The hybrid energy system in this case consists of an existing cogeneration unit extended with a new installation of thermal solar panels. This puts two complementary heating technologies in juxtaposition. The two technologies are supported with distinct regional support instruments in each region. The design and operation of the energy system is optimised from the point of view of the investor according to the different support instruments. The optimal configuration is analysed as well as its effect on reduced CO2-emissions during the lifetime of the project. The methodology is applied to a case-study for two neighbouring regions, the Netherlands and Flanders. The policies in the Netherlands show a beneficial synergy. In Flanders, the hybrid energy system is not interesting, indicating unbalanced high support for cogeneration in this case. From the point of view of the authorities, a more balanced regional policy as in the Netherlands provides a larger CO2-emission reduction for a smaller cost. (C) 2012 Elsevier Ltd. All rights reserved.

Abstract: Lignocellulosic biomass is the most abundant source of renewable biomass and is seen as a high-potential replacement for petroleum-based resources. The conversion technologies to advanced biofuels are still at a low maturity level, thus allowing for future cost reductions through technological learning. This fact is barely considered in state-of-the-art techno-economic assessments and a structured approach to account for technological learning in techno-economic assessments is needed. In this study, a framework for techno-economic assessments of advanced biofuels, integrating learning curves, is proposed. As a validation of this framework, the economic feasibility of the valorization of corn stover for the production of second-generation bioethanol in Belgium is studied. Process flowsheet simulations in Aspen Plus are developed, with an emphasis on the comparison of four different pretreatment technologies and two plant capacities at 156 dry kt biomass/y and 667 dry kt/y. The dilute acid pretreatment model of the large-scale biorefinery required the lowest minimum learning rate to reach an economically feasible biorefinery by 2030, being 3.9%, almost half as the one calculated for the smaller scale plant. This learning rate seems to be achievable based on learning rates commonly estimated in literature. We conclude that there is a potential for advanced ethanol production in Belgium under the current state of technology for large-scale biorefineries, which require additional biomass imports, when accounting for future cost reductions through learning

Abstract: Plasma-catalytic ammonia decomposition as a method for producing hydrogen was studied in a packed-bed dielectric barrier discharge (DBD) reactor at ambient pressure and a fixed plasma power. The influence of packing the plasma zone with various dielectric materials, typically used as catalyst supports, was examined. At conditions (21 W, 75 Nml/min NH3) where an NH3 conversion of 5% was achieved with plasma alone, an improved decomposition was found when introducing dielectric materials with dielectric constants between 4 and 30. Of the tested materials, MgAl2O4 yielded the highest conversion (15.1%). The particle size (0.3-1.4 mm) of the MgAl2O4 packing was found to have a modest influence on the conversion, which dropped from 15.1% to 12.6% with increasing particle size. Impregnation of MgAl2O4 with different metals was found to decrease the NH3 conversion, with the Ni impregnation still showing an improved conversion (7%) compared to plasma-only. The plasma-assisted ammonia decomposition occurs in the gas phase due to micro-discharges, as evident from a linear correlation between the conversion and the frequency of micro-discharges for both plasma alone and with the various solid packing materials. The primary function of the solid is thus to facilitate the gas phase reaction by assisting the creation of micro-discharges. Lastly, insulation of the reactor to raise the temperature to 230 degrees C in the plasma zone was found to have a negative effect on the conversion, as a change from volume discharges to surface discharges occurred. The study shows that NH3 can be decomposed to provide hydrogen by exposure to a non-thermal plasma, but further developments are needed for it to become an energy efficient technology. (C)2022 The Author(s). Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC.

Abstract: The safe and efficient use of hydrogen energy, which is in high demand worldwide today, requires efficient hydrogen storage. Despite significant advances in hydrogen storage using carbon-based nanomaterials, including carbon nanotubes (CNTs), efforts to substantially increase the storage capacity remain less effective. In this work, we demonstrate the effect of endohedral transition metal atoms on the hydrogen storage capacity of CNTs using reactive molecular dynamics simulations. We find that an increase in the volume fraction of endohedral nickel atoms leads to an increase in the concentration of physisorbed hydrogen molecules around single-walled CNTs (SWNTs) by approximately 1.6 times compared to pure SWNTs. The obtained results provide insight into the underlying mechanisms of how endohedral transition metal atoms enhance the hydrogen storage ability of SWNTs under nearly ambient conditions.

Abstract: We present a model that describes the effect of elastic constraint on the thermodynamics of hydrogen absorption and desorption in biphasic core-shell nanoparticles, where the core is a hydride forming metal. In particular, the change of the hydride formation enthalpy and of the equilibrium pressure for the metal/hydride transformation are described as a function of nanoparticles radius, shell thickness, and elastic properties of both core and shell. To test the model, the hydrogen sorption isotherms of Mg-MgO core-shell nanoparticles, synthesized by inert gas condensation, were measured by means of optical hydrogenography. The model's predictions are in good agreement with the experimentally determined plateau pressure of hydrogen absorption. The features that a core-shell systems should exhibit in view of practical hydrogen storage applications are discussed with reference to the model and the experimental results. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Abstract: Ag/ZnO nanocomposites were developed by a plasma-assisted approach. The adopted strategy exploits the advantages of Plasma Enhanced-Chemical Vapor Deposition (PE-CVD) for the growth of columnar ZnO arrays on Si(100) and Al2O3 substrates, in synergy with the infiltration power of the Radio Frequency (RF)-sputtering technique for the subsequent dispersion of different amounts of Ag nanoparticles (NPs). The resulting composites, both as-prepared and after annealing in air, were thoroughly characterized with particular attention on their morphological organization, structure and composition. For the first time, the above systems have been used as catalysts in the production of hydrogen by photo-reforming of alcoholic solutions, yielding a stable H2 evolution even by the sole use of simulated solar radiation. In addition, Ag/ZnO nanocomposites presented an excellent response in the gas-phase detection of H2, opening attractive perspectives for advanced technological applications.

Abstract: To counter global warming, a transition to a low-carbon economy is needed. The greenhouse sector can contribute by installing Combined Heat and Power (CHP) systems, known for their excellent energy efficiency. Due to the recent European liberalization of the energy market, glass horticulturists have the opportunity to sell excess electricity to the market and by tailored policy and support measures, regional governments can fill the lack of technical and economic knowledge, causing initial resistance. This research investigates the economic and environmental opportunities using two detailed cases applying a self managed cogeneration system. The Net Present Value is calculated to investigate the economic feasibility. The Primary Energy Saving, the CO2 Emission Reduction indicator and an Emission Balance are applied to quantify the environmental impact. The results demonstrate that a self-managed CHP system is economic viable and that CO2 emissions are reduced. (C) 2010 Elsevier Ltd. All rights reserved.

Abstract: Co-thermochemical conversion of coal and biomass can potentially decrease the use of fossil carbon and pollutant emissions. This work presents experimental results for the so-called top-lit updraft fixed bed reactor, in which the ignition front starts at the top and propagates downward while the gas product flows upwards. The study focuses on the ignition front propagation velocity for the co-thermochemical conversion of palm kernel shell and high-volatile bituminous coal. Within the range of assessed air superficial velocities, the process occurred under gasification and near stoichiometric conditions. Under gasification conditions increasing coal particle size from 7.1 to 22 mm decreased ignition front velocity by around 26% regardless of the coal volume percentage. Furthermore, increasing coal volume percentage and decreasing coal particle size result in product gas with higher energy content. For the operation near stoichiometric conditions, increasing coal volume percentage from 10 to 30% negatively affected the ignition front velocity directly proportional to its particle size. Additional experiments confirmed a linear dependence of ignition front velocity on air superficial velocity. Further steps in the development of the top-lit updraft technology are implementing continuous solids feeding and variable cross-sectional area and optimizing coal particle size distribution.

Abstract: Using density-functional theory in combination with the nonequilibrium Green's function formalism, we study the effect of the crystal lattice structure of organometallic perovskite CH3NH3PbI3 on its electronic transport properties. Both dispersive interactions and spin-orbit coupling are taken into account in describing structural and electronic properties of the system. We consider two different phases of the material, namely the orthorhombic and cubic lattice structures, which are energetically stable at low (< 160 K) and high (> 330 K) temperatures, respectively. The sizable geometrical differences between the two structures in term of lattice parameters, PbI6 octahedral tilts, rotation and deformations, have considerable impact on the transport properties of the material. For example, at zero bias and for all considered electron energies, the cubic phase has a larger transmission than the orthorhombic one, although both show similar electronic densities of states. Depending on the applied voltage, the current in the cubic system can be several orders of magnitude larger as compared to the one obtained for the orthorhombic sample. We attribute this enhancement in the transmission to the presence of extended states in the cubic phase due to the symmetrically shaped and ordered PbI6 octaherdra. (C) 2015 Elsevier B.V. All rights reserved.