ALBERT

Description: 〈p〉Publication date: Available online 8 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy〈/p〉 〈p〉Author(s): Muhammad Abid, Muhammad Sajid Khan, Tahir Abdul Hussain Ratlamwala〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Parabolic dish solar collector system has capability to gain higher efficiency by converting solar radiations to thermal heat due to its higher concentration ratio. This paper examines the exergo-economic analysis, net work and hydrogen production rate by integrating the parabolic dish solar collector with two high temperature supercritical carbon dioxide (s-CO〈sub〉2〈/sub〉) recompression Brayton cycles. Pressurized water (H〈sub〉2〈/sub〉O) is used as a working fluid in the solar collector loop. The various input parameters (direct normal irradiance, ambient temperature, inlet temperature, turbine inlet temperature and minimum cycle temperature) are varied to analyze the effect on net power output, hydrogen production rate, integrated system energetic and exergetic efficiencies. The simulations has been carried out using engineering equation solver (EES). The outputs demonstrate that the net power output of the integrated reheat recompression s-CO〈sub〉2〈/sub〉 Brayton system is 3177 kW, whereas, without reheat integrated system has almost 1800 kW net work output. The overall energetic and exergetic efficiencies of former system is 30.37% and 32.7%, respectively and almost 11.6% higher than the later system. The hydrogen production rate of the solarized reheat and without reheat integrated systems is 0.0125 g/sec and 0.007 g/sec, accordingly and it increases with rise in direct normal irradiance and ambient temperature. The receiver has the highest exergy destruction rate (nearly 44%) among the system components. The levelized electricity cost (LEC) of 0.2831 $/kWh with payback period of 9.5 years has proved the economic feasibility of the system design. The increase in plant life from 10 to 32 years with 8% interest rate will decrease the LEC from (0.434-0.266) $/kWh. Recuperators have more potential for improvement and their cost rate of exergy is higher as compared to the other components.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 8 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy〈/p〉 〈p〉Author(s): Yuan Xue, Shixiong Min, Fang Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Although black phosphorous (BP) and its derived materials have shown great potential for application in photocatalytic H〈sub〉2〈/sub〉 evolution reaction (HER), their HER activity and stability still remains unsatisfied mainly due to the insufficient charge separation, the lack of surface active sites, and the defect-riched nature of BP. Herein, we report that BP nanosheets decorated with in situ grown Pt (BP NSs/Pt) could act as a highly efficient catalyst for photocatalytic H〈sub〉2〈/sub〉 evolution in an Erythrosin B (ErB)-sensitized system under visible light irradiation (≥450 nm) in the presence of triethanolamine (TEOA) as sacrificial electron donor. It is found that BP NSs can provide large surface area for the confined growth of Pt nanoparticles with a high dispersion and a reduced size but also stabilize the loaded Pt nanoparticles by covalent bonds at the BP NSs/Pt interfaces. Moreover, BP NSs offer a fast electron transfer pathway to facilitate the photocatalytic HER over in situ grown Pt catalyst. As a result, BP NSs/Pt catalyst exhibits ∼6 times higher H〈sub〉2〈/sub〉 evolution activity than free Pt nanoparticles and an apparent quantum yield (AQY) of 0.57% at 500 nm irradiation in ErB-TEOA system. This work indicates the potential of BP NSs as an effective 2D matrix to construct numerous high performance photocatalysts and photocatalytic systems.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 8 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy〈/p〉 〈p〉Author(s): C. Juillet, M. Tupin, F. Martin, Q. Auzoux, C. Berthinier, F. Miserque, F. Gaudier〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Under Pressurized Water Reactor normal operating conditions, the external surface of zirconium alloys cladding absorbs a fraction of the hydrogen produced by water reduction. During spent fuel transport, hydrogen may desorb from the cladding. The study aims to identify and quantify the rate-limiting step in the hydrogen desorption process initially present in the alloy. To better understand this process, the Thermal Desorption Spectrometry (TDS) was used in association with X-ray Photoelectron Spectroscopy analysis. TDS results were analysed with finite elements simulations using the Cast3M code. The optimization of the kinetic constants of hydrogen desorption was performed with CEA (Alternative Energies and Atomic Energy Commission)-tool URANIE. Results showed that hydrogen desorption kinetics from the metal is limited by the surface molecular recombination. Arrhenius-type temperature dependence of kinetic constants allowed to simulate experimental data with a good agreement. The optimized activation energy and the pre-exponential factor for desorption processes were in the range of 290 ± 10 kJ mol〈sup〉−1〈/sup〉 and 3 × 10〈sup〉7〈/sup〉 m〈sup〉4〈/sup〉 mol〈sup〉−1〈/sup〉 s〈sup〉−1〈/sup〉 respectively.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 8 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy〈/p〉 〈p〉Author(s): Abhishek Rajput, Prem P. Sharma, Vikrant Yadav, Vaibhav Kulshrestha〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Proton exchange membrane is a basic element for any redox flow battery. Nafion is the only commercial available proton exchange membrane used in different electro-chemical energy systems. High cost restrict it's used for energy generation devices. In present work, we synthesised styrene divinylbenzene based composite proton exchange membranes (PEMs) with varying sulfonated graphene oxide (sGO) content for redox flow battery (RFB). Synthesized copolymer PEMs were analyzed in terms of their chemical structure with the help of FT-IR spectroscopy to confirm desired functional groups at appropriate position. Electrochemical characterization was performed in terms proton-exchange capacity, protonic conductivity and water uptake. Membrane shows adequate proton exchange capacity with good proton conductivity. Vanadium ion permeability was also tested for the prepared membrane to assess capability for vanadium redox flow battery (VRFB) in contrast with commercially available Nafion 117 PEM. Higher VO〈sup〉+2〈/sup〉 ion cross-over resistance was found for CEM-4 with 7.17 × 10〈sup〉−7〈/sup〉 cm〈sup〉2〈/sup〉 min〈sup〉−1〈/sup〉 permeability, which is about half of the CEM-1. Further CEM-4 was also evaluated for charging-discharging phenomenon for single cell VRFB. The values of columbic, voltage and energy efficiency for VRFB confirms prepared membrane as a good candidate for redox flow battery. Composite PEM also shows better mechanical and thermal stability. Results indicates that synthesized composite membrane can be used in vanadium redox flow battery.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0360319919323584-fx1.jpg" width="395" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 26 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy, Volume 44, Issue 36〈/p〉 〈p〉Author(s): Zhiguo Liu, Xiao Zhang, Zhixiang Jiang, Hsueh-Shih Chen, Ping Yang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Non-metal doping not only optimizes the energy band structure of g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉 to improve the absorption of visible light, but also exacerbates the distortion of lowest and highest unoccupied molecular orbital plane, causing polarization, thereby improving photocatalytic activity. For the first time, S and P are co-introduced into g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉 network to enhance photocatalytic performance and create various tubular morphologies. The ratio of S to P is crucial to control the tubular morphology and property. In the photocatalytic process, the separation of electrons and holes causes by the polarization of the S and P elements and the synergy of the tubular morphology results in new migration paths for photogenerated electrons and holes. Using optimized preparation conditions, g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉 tubes co-doped with S and P (CNSP) reveal very high H〈sub〉2〈/sub〉 generation efficiency (163.27 μmol/h), which is two orders of magnitude higher compared to that of pure g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉 and apparent quantum yield is 18.93% at 420 nm. Fast degradation of Rhodamine B by using CNSP occurs within 5 min under visible light irradiation. Because of the reproducible process, the synthetic strategy provides a novel method for controlling the morphology of g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉-based materials with super activity.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0360319919322487-fx1.jpg" width="311" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 5 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy〈/p〉 〈p〉Author(s): Shuguo Qu, Minhui Li, Chenchen Zhang, Jihai Duan, Weiwen Wang, Jianlong Li, Xiaojin Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A novel proton exchange membrane was synthesized by embedding a crystalline which was nano-assembled through trimesic acid and melamine (TMA·M) into the matrix of the sulfonated poly (ether ether ketone) (SPEEK) to enhance the proton conductivity of the SPEEK membrane. Fourier transform infrared indicated that hydrogen bonds existed between SPEEK and TMA·M. XRD and SEM indicated that TMA·M was uniformly distributed within the matrix of SPEEK, and no phase separation occurred. Thermogravimetric analysis showed that this membrane could be applied as high temperature proton exchange membrane until 250 °C. The dimensional stability and mechanical properties of the composite membranes showed that the performance of the composite membranes is superior to that of the pristine SPEEK. Since TMA·M had a highly ordered nanostructure, and contained lots of hydrogen bonds and water molecules, the proton conductivity of the SPEEK/TMA·M-20% reached 0.00513 S cm〈sup〉−1〈/sup〉 at 25 °C and relative humidity 100%, which was 3 times more than the pristine SPEEK membrane, and achieved 0.00994 S cm〈sup〉−1〈/sup〉 at 120 °C.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 19 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy, Volume 44, Issue 35〈/p〉 〈p〉Author(s): Ying Han, Weirong Chen, Qi Li, Hanqing Yang, Firuz Zare, Yongkang Zheng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉With the fast development of DC Microgrid (MG) technology, its operating economy and reliability are getting more and more concern. The traditional distributed control method is aimed at power balance and system stability, and is difficult to meet the requirement of energy management system for multi-source hybrid DC MG. This paper provides a two-level energy management strategy for PV-fuel cell-battery-based DC MG, which is divided into device control level and system control level. At the device control level, the distributed control methods based on MPPT-droop dual-mode control and droop control are proposed to enhance system reliability; at the system control level, the equivalent consumption minimization strategy (ECMS) is used to distribute system net power between battery pack and fuel cell system. A lab-scale DC microgrid platform is developed to verify the proposed energy management strategy in this paper. Moreover, the analysis and compare of the results show that the proposed two-level energy management strategy can achieve lower equivalent hydrogen consumption than classical PI control and state machine control method.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 19 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy, Volume 44, Issue 35〈/p〉 〈p〉Author(s): Nicolás Cobos Ullvius, Masoud Rokni〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉While energy demand in this fast developing world is increasing, its future is being compromised by the CO〈sub〉2〈/sub〉 emissions produced through the burning of fossil fuels. Clean energy technologies are available, but there are still barriers hindering their full integration into the society, the majority of which are economic and social. For these reasons, the development of new technologies and configurations to make renewable energies systems more cost-effective is urgently needed. The plant design proposed in this paper consists of basic Dish-Stirling collectors supported by a reversible solid oxide fuel cell acting as a power generator and storage unit, and therefore offering dispatchable power on demand. Further, the system reuses the waste heat for seawater desalination, which is very convenient for arid areas with high solar radiation and shortage of freshwater. The present work is an analytical study in which thermodynamic investigation of the performance evaluation of a self-sustainable polygeneration system with integrated hydrogen production, power generation, and freshwater production is conducted. An evaluation in a real context (South Africa) showed the potential of this system to supply 500 kW, 24 h a day, while producing a considerable amount of freshwater. Although the distillation system presented is able to produce 8464 L per day, there is potential for it to increase its output by nine times or more.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 6 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy〈/p〉 〈p〉Author(s): Hongri Wan, Xiaofang Hu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Nitrogen/sulfur co-doped disordered porous biocarbon was facilely synthesized and applied as anode materials for lithium/sodium ion batteries. Benefiting from high nitrogen (3.38 wt%) and sulfur (9.75 wt%) doping, NS〈sub〉1-1〈/sub〉 as anode materials showed a high reversible capacity of 1010.4 mA h g〈sup〉−1〈/sup〉 at 0.1 A g〈sup〉−1〈/sup〉 in lithium ion batteries. In addition, it also exhibited excellent cycling stability, which can maintain at 412 mAh g〈sup〉-1〈/sup〉 after 1000 cycles at 5 A g〈sup〉−1〈/sup〉. As anode materials of sodium ion batteries, NS〈sub〉1-1〈/sub〉 can still reach 745.2 mA h g〈sup〉−1〈/sup〉 at 100 mAg〈sup〉-1〈/sup〉 after 100 cycles. At a high current density (5 A g〈sup〉-1〈/sup〉), the reversible capacity is 272.5 mA h g〈sup〉−1〈/sup〉 after 1000 cycles, which exhibits excellent electrochemical performance and cycle stability. The preeminent electrochemical performance can be attributed to three effects: (1) the high level of sulfur and nitrogen; (2) the synergic effect of dual-doping heteroatoms; (3) the large quantity of edge defects and abundant micropores and mesopores, providing extra Li/Na storage regions. This disordered porous biocarbon co-doped with nitrogen/sulfur exhibits unique features, which is very suitable for anode materials of lithium/sodium ion batteries.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0360319919323572-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 6 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy〈/p〉 〈p〉Author(s): Zhilong Wei, Haisheng Zhen, Jin Fu, Chunwah Leung, Chunshun Cheung, Zuohua Huang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The laminar burning velocities of biogas-hydrogen-air mixture at different fuel compositions and equivalence ratios were determined and studied using the spherical flame method. The combined effects of H〈sub〉2〈/sub〉 and CO〈sub〉2〈/sub〉 on the laminar burning velocity were investigated quantitatively based on the kinetic effects and the thermal effects. The results show that the laminar burning velocities of the BG40, BG50 and BG60 are increased almost linearly with the H〈sub〉2〈/sub〉 addition owing to the improved fuel kinetics and the increased adiabatic flame temperature. The dropping trend of laminar burning velocity from the BG60-hydrogen to the BG40-hydrogen is primarily attributed to the decreased adiabatic flame temperature (thermal effects). The GRI 3.0 mechanism can predict the laminar burning velocity of biogas-hydrogen mixture better than the San Diego mechanism in this study. Whereas, the GRI mechanism still needs to be modified properly for the hydrogen-enriched biogas as the CO〈sub〉2〈/sub〉 proportion exceeds 50% in the biogas at the fuel-rich condition. The increased CO〈sub〉2〈/sub〉 exerts the stronger suppression on the net reaction rate of H + O〈sub〉2〈/sub〉=OH + O than that of H + CH〈sub〉3〈/sub〉(+M) = CH〈sub〉4〈/sub〉(+M), which contributes to that the rich-shift of peak laminar burning velocity of biogas-hydrogen mixture requires higher H〈sub〉2〈/sub〉 addition as the CO〈sub〉2〈/sub〉 content is enhanced. For the biogas-hydrogen fuel, the H〈sub〉2〈/sub〉 addition decreases the flame stability of biogas fuel effectively due to the increased diffusive-thermal instability and hydrodynamic instability. The improved flame stability of biogas-hydrogen fuel with the increased CO〈sub〉2〈/sub〉 content is resulted from the combined effects of diffusive-thermal instability and hydrodynamic instability.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 19 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy, Volume 44, Issue 35〈/p〉 〈p〉Author(s): Guorui Zhang, Qi Li, Weirong Chen, Xiang Meng, Huiwen Deng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In order to improve the robustness of the energy management system (EMS) and avoid the influence of demand power on the design of EMS, a coupled power-voltage equilibrium strategy based on droop control (CPVE-DC) is proposed in this paper. Making use of the principal that the DC bus can directly reflect the changes of load power, the proposed strategy couples DC bus voltage with output powers through droop control to achieve self-equilibrium. The proposed EMS is applied into a hybrid tramway model configured with multiple proton exchange membrane fuel cell (PEMFC) systems, batteries and super capacitors (SCs). FC systems and SC systems are responsible for satisfying most of the demand power, therefore the CPVE-DC strategy generates FCs and SCs reference power through power-voltage droop control on the primary control. Then batteries supplement the rest part of load power and generate DC bus voltage reference value of the next sampling time. With the gambling between output power and DC bus voltage, the hybrid system achieves self-equilibrium and steps into steady operation by selecting appropriate droop coefficients. Then the secondary control of the proposed strategy allocates power between every single unit. In addition, a penalty coefficient is introduced to balance SOC of SCs. The proposed strategy is tested under a real drive cycle LF-LRV on RT-LAB platform. The results demonstrate that the proposed strategy can achieve self-equilibrium and is effective to allocate demand power among these power sources，achieve active control for the range of DC bus voltage and SOC consensus of SCs as well. In addition, some faults are simulated to verify the robustness of the proposed strategy and it turns out that the CPVE-DC strategy possesses higher robustness. Finally, the CPVE-DC strategy is compared with equivalent consumption minimization strategy (ECMS) and the results shows that the proposed strategy is able to get higher average efficiency and lower equivalent fuel consumption.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 26 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy, Volume 44, Issue 36〈/p〉 〈p〉Author(s): Alexander N. Bondarchuk, Iván Corrales-Mendoza, Sergio A. Tomás, Frank Marken〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Photoelectrochemical water splitting using solar energy is a highly promising technology to produce hydrogen as an environmentally friendly and renewable fuel with high-energy density. This approach requires the development of appropriate photoelectrode materials and substrates, which are low-cost and applicable for the fabrication of large area electrodes. In this work, hematite photoelectrodes are grown by aerosol assisted chemical vapour deposition (AA-CVD) onto highly-conductive and bulk porous SnO〈sub〉2〈/sub〉 (Sb-doped) ceramic substrates. For such photoelectrodes, the photocurrent density of 2.8 mA cm〈sup〉-2〈/sup〉 is achieved in aqueous 0.1 M NaOH under blue LED illumination (〈em〉λ〈/em〉 = 455 nm; 198 mW cm〈sup〉-2〈/sup〉) at 1.23 V vs. RHE (reversible hydrogen electrode). This relatively good photoelectrochemical performance of the photoelectrode is achieved despite the simple fabrication process. Good performance is suggested to be related to the three-dimensional morphology of the porous ceramic substrate resulting in excellent light-driven charge carrier harvesting. The porosity of the ceramic substrate allows growth of the photoactive layer (SnO〈sub〉2〈/sub〉-grains covered by hematite) to a depth of some micrometers, whereas the thickness of Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉-coating on individual grains is only about 100–150 nm. This architecture of the photoactive layer assures a good light absorption and it creates favourable conditions for charge separation and transport.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 19 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy, Volume 44, Issue 35〈/p〉 〈p〉Author(s): J. Büsselmann, M. Rastedt, V. Tullius, K. Yezerska, A. Dyck, P. Wagner〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉With the help of consistent conditions for improved batch production and defined quality standards, the lifetime of fuel cell systems should be improved and cost-intensive losses should be minimized at an early state in the production process. Within this work, we concentrated on two accelerated stress tests: load cycling at high current densities and start/stop cycling to compare high temperature (HT) polymer electrolyte membrane (PEM) membrane electrode assemblies (MEAs) of three suppliers to evaluate performances and degradation rates under such conditions. These MEAs have been investigated in-situ via electrochemical characterization. MEAs of three providers differ significantly in their performance and power output for both operation strategies. It was also shown that load cyclization causes greater stress on the MEA than start/stop cycling. Next to the manufacturer comparison, a batch-to-batch evaluation of one provider has been performed including micro-computed tomography (μ-CT) investigations and the determination of the tortuosity of the cathode side gas diffusion layers.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 19 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy, Volume 44, Issue 35〈/p〉 〈p〉Author(s): Gisela Orcajo, Helena Montes-Andrés, José A. Villajos, Carmen Martos, Juan A. Botas, Guillermo Calleja〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The organometallic Li-Crown ether species, formed by the complexation of lithium cation with the hydrophobic 18Crown6 ether, has been included in three Metal-Organic-Framework〈del〉s〈/del〉 (MOF) structures with different pore size: Cr-MIL-101, Fe-MIL100 and Ni-MOF-74. X-ray powder diffraction, thermogravimetric analysis, proton nuclear magnetic resonance, infrared spectroscopy and inductively coupled plasma atomic emission spectroscopy measurements have proved the successful incorporation of the organometallic units to the three MOFs without altering their crystalline structure. Hydrogen adsorption properties of the post-synthesis modified materials have been evaluated in a wide temperature (77–298 K) and pressure (1–170 bar) range conditions. The post-synthetic modification method used based on the MOF impregnation with a Li-Crown ether complex solution produced a partial pore blocking effect on the microporous Ni-MOF-74, reducing its hydrogen adsorption capacity. However, the inclusion of the crown-ether and particularly the Li-Crown ether complex resulted in an increase of the volumetric hydrogen adsorption capacity at room temperature for Cr-MIL101 and Fe-MIL-100, due to the pore volume reduction, higher confinement of H〈sub〉2〈/sub〉 molecules in the cavities and the formation of new specific binding sites for H〈sub〉2〈/sub〉 molecules. The inclusion of Li-Crown ether complex also enhances the H〈sub〉2〈/sub〉 interaction with the mesoporous MOF structures, attributed to the additional electrostatic interactions produced by the presence of Li〈sup〉+〈/sup〉 ions complexed to the crown ether molecules. Further work following this strategy to improve hydrogen adsorption capacity of mesoporous MOFs at room temperature should be extended to other MOF materials, checking its influence on their capacity for gas separation purposes.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 19 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy, Volume 44, Issue 35〈/p〉 〈p〉Author(s): Quentin Bellouard, Sylvain Rodat, Stéphane Abanades, Serge Ravel, Pierre-Éric Frayssines〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The use of concentrated solar energy as the high-temperature heat source for the thermochemical gasification of biomass is a promising prospect for producing CO〈sub〉2〈/sub〉-neutral chemical fuels (syngas). The solar process saves biomass resource because partial combustion of the feedstock is avoided, it increases the energy conversion efficiency because the calorific value of the feedstock is upgraded by the solar power input, and it also reduces the need for downstream gas cleaning and separation because the gas products are not contaminated by combustion by-products. A new concept of solar spouted bed reactor with continuous biomass injection was designed in order to enhance heat transfer in the reactor, to improve the gasification rates and gas yields by providing constant stirring of the particles, and to enable continuous operation. Thermal simulations of the prototype were performed to calculate temperature distributions and validate the reactor design at 1.5 kW scale. The reliable operation of the solar reactor based on this new design was also experimentally demonstrated under real solar irradiation using a parabolic dish concentrator. Wood particles were continuously gasified at temperatures ranging from 1100 °C to 1300 °C using either CO〈sub〉2〈/sub〉 or steam as oxidizing agent. Carbon conversion rates over 94% and gas productions over 70 mmol/g〈sub〉biomass〈/sub〉 were achieved. The energy contained in the biomass was upgraded thanks to the solar energy input by a factor of up to 1.21.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S036031991831334X-fx1.jpg" width="244" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 19 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy, Volume 44, Issue 35〈/p〉 〈p〉Author(s): Antonio Valente, Diego Iribarren, Javier Dufour〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The environmental sustainability of hydrogen energy systems is often evaluated through Life Cycle Assessment (LCA). In particular, environmental suitability is usually determined by comparing the life-cycle indicators calculated for a specific hydrogen energy system with those of a reference system (e.g., conventional hydrogen from steam methane reforming, SMR-H〈sub〉2〈/sub〉). In this respect, harmonisation protocols for comparative LCA of hydrogen energy systems have recently been developed in order to avoid misleading conclusions in terms of carbon footprints and cumulative energy demand. This article expands the scope of these harmonisation initiatives by addressing a new life-cycle indicator: acidification. A robust protocol for harmonising the acidification potential of hydrogen energy systems is developed and applied to both SMR-H〈sub〉2〈/sub〉 and a sample of case studies of renewable hydrogen. According to the results, unlike other energy systems, there is no correlation between acidification and carbon footprint in the case of hydrogen energy systems, which prevents the estimation of harmonised acidification results from available harmonised carbon footprints. Nevertheless, an initial library of harmonised life-cycle indicators of renewable hydrogen is now made available.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 19 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy, Volume 44, Issue 35〈/p〉 〈p〉Author(s): Paul Brack, S.E. Dann, K.G.U. Wijayantha, Paul Adcock, Simon Foster〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Ferrosilicon 75, a 50:50 mixture of silicon and iron disilicide, has been activated toward hydrogen generation by processing using ball milling, allowing a much lower concentration of sodium hydroxide (2 wt %) to be used to generate hydrogen from the silicon in ferrosilicon with a shorter induction time than has been reported previously. An activation energy of 62 kJ/mol was determined for the reaction of ball-milled ferrosilicon powder with sodium hydroxide solution, which is around 30 kJ/mol lower than that previously reported for unmilled ferrosilicon. A series of composite powders were also prepared by ball milling ferrosilicon with various additives in order to improve the hydrogen generation properties from ferrosilicon 75 and attempt to activate the silicon in the passivating FeSi〈sub〉2〈/sub〉 component. Three different classes of additives were employed: salts, polymers and sugars. The effects of these additives on hydrogen generation from the reaction of ferrosilicon with 2 wt% aqueous sodium hydroxide were investigated. It was found that composites formed of ferrosilicon and sodium chloride, potassium chloride, sodium polyacrylate, sodium polystyrene sulfonate-co-maleic acid or fructose showed reduced induction times for hydrogen generation compared to that observed for ferrosilicon alone, and all but fructose also led to an increase in the maximum hydrogen generation rate. In light of its low cost and toxicity and beneficial effects, sodium chloride is considered to be the most effective of these additives for activating the silicon in ferrosilicon toward hydrogen generation. Materials characterisation showed that neither ball milling on its own nor use of additives was successful in activating the FeSi〈sub〉2〈/sub〉 component of ferrosilicon for hydrogen generation and the improvement in rate and shortening of the induction period was attributed to the silicon component of the mixture alone The gravimetric storage capacity for hydrogen in ferrosilicon 75 is therefore maintained at only 3.5% rather than the 10.5% ideally expected for a material containing 75% silicon. In light of these results, ferrosilicon 75 does not appear a good candidate for hydrogen production in portable applications.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 19 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy, Volume 44, Issue 35〈/p〉 〈p〉Author(s): Ioan Iordache, Karel Bouzek, Martin Paidar, Karin Stehlík, Johannes Töpler, Mirosław Stygar, Juliusz Dąbrowa, Tomasz Brylewski, Ioan Stefanescu, Mihaela Iordache, Dorin Schitea, Sergey A. Grigoriev, Vladimir N. Fateev, Viacheslav Zgonnik〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The article contains examples about hydrogen research and development progress in different countries: Czech Republic, Poland, Romania, Russia and Ukraine. Each chapter describes a specific situation for a country and one of them describes some aspects from Germany for comparison with one of international leaders. The examples described into articles are not aleatory. The intention of the authors is to give to the reader the possibility to understand the concrete examples about what means the state of hydrogen and fuel cell research and innovation in the Central and Eastern European countries. The chapters dedicated to Czech Republic, Poland, and Romania, reveal the commitment of these countries in this adventure, often viewed today as a subject of very advanced countries. The specific situation in the Russia Federation describes a strong background, an uncertain present and a questionable future for the hydrogen and fuel cell technology. Development of hydrogen technologies and fuel cells in Ukraine have a long history, also. All of that, in the EU context, by voice of the main stakeholders, considered the hydrogen and fuel cell a decisive issue, with economic and societal ramifications.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 19 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy, Volume 44, Issue 35〈/p〉 〈p〉Author(s): Evangelos I. Gkanas, Thomas Statheros, Martin Khzouz〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A numerical study fully validated with solid experimental results is presented and analysed, regarding the hydrogenation process of rectangular metal hydride tanks for green building applications. Based on a previous study conducted by the authors, where the effective heat management of rectangular tanks by using plain embedded cooling tubes was analysed, in the current work the importance of using extended surfaces to enhance the thermal properties and the hydrogenation kinetics is analysed. The studied extended surfaces (fins) were of rectangular shape; and several combinations regarding the number of fins and the fin thickness were examined and analysed. The values for fin thickness were 2-3-5 and 8 mm and the number of fins studied were 10-14-18 and 20. To evaluate the effect of the heat management process, a modified version of a variable named as Non-Dimensional Conductance (NDC) is introduced and studied. A novel AB〈sub〉2〈/sub〉-Laves phase intermetallic was considered as the metal hydride for the study. The results of the hydrogenation behaviour for the introduced parameters (fin number and thickness) showed that the rectangular tank equipped with the cooling tubes in combination with 14 fins of 5 mm fin thickness has the capability of storing hydrogen over 90% of its theoretical capacity in less than 30 min.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 4 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy〈/p〉 〈p〉Author(s): Zhao-Hui Ruan, Yu-Dong Li, Yuan Yuan, Kai-Feng Lin, He-Ping Tan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉As is reported, the photocatalytic activity will increase significantly when TiO〈sub〉2〈/sub〉 nanoparticles are agglomerated into TiO〈sub〉2〈/sub〉 nanofibers (NFs), but the photocatalytic activity enhancement mechanisms are still not fully understood. As is widely accepted, the optical absorption process plays a key role in photocatalysis, and it can even be said that the optical absorption capability of the photocatalyst directly determines its photocatalytic activity, while the influence of the structure on the optical absorption characteristics of TiO〈sub〉2〈/sub〉 has largely been ignored in the existing explanations. In this paper, optical simulations are introduced into analyzing optical characteristics of TiO〈sub〉2〈/sub〉 Nanofibers with which, the photocatalytic activity enhancement mechanism is further discussed, and a photocatalytic activity enhancement mechanism of TiO〈sub〉2〈/sub〉 Nanofibers is proposed.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 19 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy, Volume 44, Issue 35〈/p〉 〈p〉Author(s): Chenhuan Zhao, Xuegang Liu, Wenqiang Zhang, Yun Zheng, Yifeng Li, Bo Yu, Jianchen Wang, Jing Chen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉To make full use of the advantages of solid oxide cells (SOCs) under actual operating conditions, hetero-structured La〈sub〉0.6〈/sub〉Sr〈sub〉0.4〈/sub〉CoO〈sub〉3-δ〈/sub〉/LaSrCoO〈sub〉4±δ〈/sub〉 (LSC〈sub〉113/214〈/sub〉) thin film electrodes are prepared and investigated by a novel high temperature micro-probe electrochemical test platform for SOCs. The results show that the surface exchange coefficient (k〈sup〉q〈/sup〉) of LSC〈sub〉113/214〈/sub〉 thin films is 3–10 times higher than that of single phase LSC〈sub〉113〈/sub〉 in 773–1123 K. ToF-SIMS and XPS characterizations show that LSC〈sub〉113/214〈/sub〉 hetero-interface leads to Sr enrichment at interfacial region and stabilizes it against detrimental Sr segregation. This hetero-interface further induces increased number of active oxygen vacancies and leads to accelerated oxygen exchange kinetics by raising O 2p center closer to Fermi level. This work provides significantly enhanced ORR/OER activity of hetero-structured LSC〈sub〉113/214〈/sub〉 oxygen electrode at operation conditions and brings substantial technical benefits for the SOC systems.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 19 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy, Volume 44, Issue 35〈/p〉 〈p〉Author(s): Penghui Feng, Luying Zhu, Yang Zhang, Fusheng Yang, Zhen Wu, Zaoxiao Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉As the well-known solid hydrogen storage materials, metal hydrides (MHs) have been developed systematically for decades. During recent years, due to the development of thermal energy storage (TES) market, they have also received much attention gradually as the excellent TES materials because of the high energy density, low cost, and good reversibility. In this study, the stabilized discharging performance of an MH reactor for TES was investigated by numerical simulation. A mathematical model combining multi-physics and proportional-integral controller was established. Based on finite-time thermodynamics, gravimetric exergy-output rate (〈em〉GEOR〈/em〉) considering the control requirement, finite-material, and finite-time constraints was defined. For a given reactor, the output temperature setting could be optimized based on 〈em〉GEOR〈/em〉. Besides, the effects of the reactor parameters on the optimum output temperature setting were systematically studied. The heat transfer analysis indicated the occurrence of the axial non-uniform reaction in the bed due to the inherent increase in the temperature of heat transfer fluid, resulting in the decrease of both 〈em〉GEOR〈/em〉 and material availability. Accordingly, a new tapered bed structure (〈em〉L〈/em〉/〈em〉D〈/em〉〈sub〉o〈/sub〉 = 600/50 mm) was proposed to effectively improve the discharging efficiency from 76 to 90% and 〈em〉GEOR〈/em〉 from 65 to 120 W kg〈sup〉−1〈/sup〉, which provides a helpful guidance for the advanced designing and construction of MH reactor for the practical TES applications.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 4 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy〈/p〉 〈p〉Author(s): P. Karthik, T.R. Naveen Kumar, B. Neppolian〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Graphitic carbon nitride (g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉) is one of the promising two-dimensional metal-free photocatalysts for solar water splitting. Regrettably, the fast electron-hole pair recombination of g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉 reduces their photocatalytic water splitting efficiency. In this work, we have synthesized the CuO/g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉 heterojunction via wet impregnation followed by a calcination method for photocatalytic H〈sub〉2〈/sub〉 production. The formation of CuO/g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉 heterojunction was confirmed by XRD, UV–vis and PL studies. Notably, the formation of heterojunction not only improved the optical absorption towards visible region and also enhanced the carrier generation and separation as confirmed by PL and photocurrent studies. The photocatalytic H〈sub〉2〈/sub〉 production results revealed that CuO/g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉 photocatalyst demonstrated the increased photocatalytic H〈sub〉2〈/sub〉 production rate than bare g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉. The maximum H〈sub〉2〈/sub〉 production rate was obtained with 4 wt % CuO loaded g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉 photocatalyst. Importantly, the rate of H〈sub〉2〈/sub〉 production was further improved by introducing simple redox couple Co〈sup〉2+〈/sup〉/Co〈sup〉3+〈/sup〉. Addition of Co〈sup〉2+〈/sup〉 during photocatalytic H〈sub〉2〈/sub〉 production shuttled the photogenerated holes by a reversible conversion of Co〈sup〉2+〈/sup〉 to Co〈sup〉3+〈/sup〉 with accomplishing water oxidation. The effective shuttling of photogenerated holes decreased the election-hole pair recombination and thereby enhancing the photocatalytic H〈sub〉2〈/sub〉 production rate. It is worth to mention that the addition of Co〈sup〉2+〈/sup〉 with 4 wt % CuO/g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉 photocatalyst showed ∼7.5 and ∼2.0 folds enhanced photocatalytic H〈sub〉2〈/sub〉 production rate than bare g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉/Co〈sup〉2+〈/sup〉 and CuO/g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉 photocatalysts. Thus, we strongly believe that the present simple redox couple mediated charge carrier separation without using noble metals may provide a new idea to reduce the recombination rate.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0360319919322566-fx1.jpg" width="268" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 19 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy, Volume 44, Issue 35〈/p〉 〈p〉Author(s): B.A. Braz, V.B. Oliveira, A.M.F.R. Pinto〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉A great challenge in a passive direct methanol fuel cell (pDMFC) is how to reduce both methanol and water crossover, from the anode to the cathode side, without significant losses on its power output. Different approaches including improving the membrane and modifying the cell structure and materials have been proposed in the last years.〈/p〉 〈p〉In this work, an experimental study was carried out to evaluate the effect of the cathode diffusion layer (CDL) properties on the power output of a pDMFC. Towards a cost reduction, lower catalyst loadings were used on both anode and cathode electrodes. Since the main goal was the optimization of a pDMFC using the materials commercially available, different carbon-fibber materials were employed as CDL. The experimental results were analysed based on the polarization curves and electrochemical impedance spectroscopy measurements with innovative electric equivalent circuit allowing the identification of the different losses, including the activation resistance of the parasitic cathode methanol oxidation.〈/p〉 〈p〉A maximum power density of 3.0 mW/cm〈sup〉2〈/sup〉 was obtained using carbon cloth with a lower thickness as CDL and a methanol concentration of 5 M.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 19 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy, Volume 44, Issue 35〈/p〉 〈p〉Author(s): A. Herrmann, A. Mädlow, H. Krause〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉The project H2home – decentralised energy supply by hydrogen fuel cells – is part of the HYPOS initiative (Hydrogen Power Storage & Solutions East German) and has the aim to develop an embedded system suitable for the highly efficient use of electrical, thermal and cooling energy provided by green hydrogen in domestic applications. This system is characterized by a hydrogen CHP plant based on a low temperature PEM fuel cell and a hydrogen-based heat generator module with the application of condensation technology as well as an integrated solution for the use of electrical energy in an AC and DC grid through power electronic components. The electric efficiency of the CHP is nearly 50% and the total efficiency higher than 95%.〈/p〉 〈p〉To evaluate the performance of the proposed technology the first step was to model a reference case using the simulation tool TRNSYS〈sup〉®〈/sup〉. Therefore, a multi-family house with 16 residential units was chosen. Within the next step different technologies for the energy supply in complex buildings were identified and evaluated. For this purpose, various Key Performance Indicators (KPI's) have been defined and summarized in three main groups allowing a technical, ecological and economical comparison of the selected technologies. The method as well as the main results of the KPI investigations will be explained in the present paper.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 19 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy, Volume 44, Issue 35〈/p〉 〈p〉Author(s): Karin Stehlík, Martin Tkáč, Karel Bouzek〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Although activities in hydrogen technologies in the Czech Republic date back to the 60'ies of the 20th century, significant progress in research and implementation appeared only in the 21st century. The acceleration is linked to the foundation of the Czech Hydrogen Technology Platform (HYTEP) in 2007. The mission of HYTEP is to inform and coordinate implementation of hydrogen economy in the Czech Republic.〈/p〉 〈p〉The last three years brought visible changes. The most important one is that hydrogen mobility is part of the national action plan for clean mobility. During the conference WHTC 2017 in Prague the Ministry of Transport and the Ministry of Environment announced support for construction of over 100 hydrogen refilling stations and more than 100,000 hydrogen cars and buses until 2030. Thanks to this governmental activities also first commercial subject developed plans how utilize the potential of hydrogen technologies.〈/p〉 〈p〉In the future HYTEP has the ambition to initiate coordination with other former East Bloc countries. The objective is to strengthen active participation of this region in European efforts and to link it to European networks and strategies to turn regional stakeholders into active participants in hydrogen technologies.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 19 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy, Volume 44, Issue 35〈/p〉 〈p〉Author(s): Wei-Chieh Chung, Yun-En Lee, Moo-Been Chang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Anthropogenic emission of CH〈sub〉4〈/sub〉 and CO〈sub〉2〈/sub〉 contributes for most of global warming. Hence, simultaneous conversion of CH〈sub〉4〈/sub〉 and CO〈sub〉2〈/sub〉 into syngas (dry reforming of methane) can be a promising way to alleviate climate change. In this work, we developed a series of perovskite-type photocatalysts, based on LaFeO〈sub〉3〈/sub〉 with various calcination temperatures to combine with a spark discharge reactor to form a hybrid plasma photocatalysis reactor. The hybrid reactor is applied for dry reforming of methane to investigate the syngas generation rate and to reveal possible interactions between plasma and photocatalyst. Results show that LFO600-packed bed has the best CH〈sub〉4〈/sub〉 and CO〈sub〉2〈/sub〉 conversions and syngas generation efficiency of 53.6%, 40.0% and 18.4 mol/kWh, respectively. The enhancement of syngas generation rate can be attributed to synergies between LFO and plasma. Furthermore, changing calcination temperature of photocatalyst also leads to variable characteristics of photocatalyst and hence plasma photocatalysis performance for syngas production.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 19 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy, Volume 44, Issue 35〈/p〉 〈p〉Author(s): Odtsetseg Myagmarjav, Jin Iwatsuki, Nobuyuki Tanaka, Hiroki Noguchi, Yu Kamiji, Ikuo Ioka, Shinji Kubo, Mikihiro Nomura, Tetsuya Yamaki, Shinichi Sawada, Toshinori Tsuru, Masakoto Kanezashi, Xin Yu, Masato Machida, Tatsumi Ishihara, Hiroaki Abekawa, Masahiko Mizuno, Tomoyuki Taguchi, Yasuo Hosono, Yoshiro Kuriki〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Thermochemical hydrogen production has attracted considerable interest as a clean energy solution to address the challenges of climate change and environmental sustainability. The thermochemical water-splitting iodine-sulfur (IS) process uses heat from nuclear or solar power and thus is a promising next-generation thermochemical hydrogen production method that is independent of fossil fuels and can provide energy security. This paper presents the current state of research and development (R&D) of the IS process based on membrane techniques using solar energy at a medium temperature of 600 °C. Membrane design strategies have the most potential for making the IS process using solar energy highly efficient and economical and are illustrated here in detail. Three aspects of membrane design proposed herein for the IS process have led to a considerable improvement of the total thermal efficiency of the process: membrane reactors, membranes, and reaction catalysts. Experimental studies in the applications of these membrane design techniques to the Bunsen reaction, sulfuric acid decomposition, and hydrogen iodide decomposition are discussed.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 19 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy, Volume 44, Issue 35〈/p〉 〈p〉Author(s): Yi-Hsuan Liang, Ming-Wei Liao, Mrinalini Mishra, Tsong-Pyng Perng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Based on the Z-scheme mechanism, the combination of two semiconductors with suitable bandgaps can reduce the recombination rate of electrons and holes in a single material to enhance photocatalytic hydrogen evolution. Ta〈sub〉3〈/sub〉N〈sub〉5〈/sub〉 with suitable band gap positions is a potentially promising material for photocatalysis. In order to raise the hydrogen production rate, ZnO nanocrystals were deposited by atomic layer deposition (ALD) on Ta〈sub〉3〈/sub〉N〈sub〉5〈/sub〉 to form a direct Z-scheme structure, ZnO@Ta〈sub〉3〈/sub〉N〈sub〉5〈/sub〉. The ALD cycle number varied from 200 to 500. All of the direct Z-scheme samples exhibited much higher hydrogen evolution efficiencies than Ta〈sub〉3〈/sub〉N〈sub〉5〈/sub〉, ZnO, and the indirect Z-scheme, with the order of ZnO300@Ta〈sub〉3〈/sub〉N〈sub〉5〈/sub〉〉ZnO200@Ta〈sub〉3〈/sub〉N〈sub〉5〈/sub〉〉ZnO400@Ta〈sub〉3〈/sub〉N〈sub〉5〈/sub〉〉ZnO500@Ta〈sub〉3〈/sub〉N〈sub〉5〈/sub〉. Because of the uniform distribution, discrete particles, and proper size of ZnO, ZnO300@Ta〈sub〉3〈/sub〉N〈sub〉5〈/sub〉 showed the highest hydrogen evolution rate, being about 500 μmol/g-h. With 400 or 500 ALD cycles, the larger particles of ZnO would overlap with each other to form a continuous layer on Ta〈sub〉3〈/sub〉N〈sub〉5〈/sub〉, thus reducing the exposure of Ta〈sub〉3〈/sub〉N〈sub〉5〈/sub〉 to the light and water for producing hydrogen.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 4 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy〈/p〉 〈p〉Author(s): Ahmed Sadeq Al-Fatesh, Jehad K. Abu-Dahrieh, Hanan Atia, Udo Armbruster, Ahmed A. Ibrahim, Wasim U. Khan, Ahmed Elhag Abasaeed, Anis H. Fakeeha〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this paper, the effect of pre-treatment and calcination temperature on a series of 5%Co/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉-ZrO〈sub〉2〈/sub〉, 5%Ni/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉-ZrO〈sub〉2〈/sub〉 and 2.5%Co-2.5%Ni/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉-ZrO〈sub〉2〈/sub〉 catalysts for dry reforming of methane was investigated. Main focus of our research was to improve the catalyst stability by proper pre-treatment and reaction conditions. The first approach aimed at the catalyst pre-treatment by using bimetallic systems and the second strategy at the 〈em〉in situ〈/em〉 suppression of coke. The catalytic activity of bimetallic system was indeed higher compared to the monometallic in the temperature range of 500–800 °C (space velocity 18000 ml h〈sup〉−1〈/sup〉·g〈sub〉cat〈/sub〉〈sup〉−1〈/sup〉, CH〈sub〉4〈/sub〉/CO〈sub〉2〈/sub〉 = 1). The bimetallic catalyst calcined at 800 °C showed highest CH〈sub〉4〈/sub〉 conversion without deactivation and gave a H〈sub〉2〈/sub〉/CO ratio of 91% and 0.96, respectively, and good stability with less coke deposition over 28 h at 800 °C reaction temperature. This improvement is assigned to the synergism between Co and Ni, their high dispersion according to interaction with support. It has been shown in our work that pretreatment temperatures and atmospheres have strong impact on stability of the catalyst. TEM, XRD and TPO investigations confirmed that the slight catalyst deactivation was related to the formation of multiwall carbon nanotubes with hollow inner tube structure. The addition of small amounts of steam or oxygen during DRM improved both the catalyst activity and stability as the bimetallic catalyst lost around 9.4% conversion in DRM, 5.4% in presence of water and only 3.2% in presence of O〈sub〉2〈/sub〉.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 19 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy, Volume 44, Issue 35〈/p〉 〈p〉Author(s): Jakub Kupecki, Ryszard Kluczowski, Davide Papurello, Andrea Lanzini, Michał Kawalec, Mariusz Krauz, Massimo Santarelli〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉The current study was oriented at analyzing the performance of an anode-supported solid oxide fuel cell produced using high-pressure injection molding. The cell with a total thickness of 550 μm was produced in the Ceramic Department (CEREL) of the Institute of Power Engineering in Poland and experimentally analyzed in the Energy Department (DENERG) of Politecnico di Torino in Italy. The high-pressure injection molding technique was applied to produce a 500 μm thick anode support NiO/8YSZ 66/34 wt% with porosity of 25 vol%. The screen printing method was used to print a 3 μm thick NiO anode contact layer, 7 μm thick NiO/8YSZ 50/50 wt% anode functional layer, 4 μm thick 8YSZ dense electrolyte, 1.5 μm thick Gd〈sub〉0,1〈/sub〉Ce〈sub〉0,9〈/sub〉O〈sub〉2〈/sub〉 barrier layer and a 30 μm thick La〈sub〉0,6〈/sub〉Sr〈sub〉0,4〈/sub〉Fe〈sub〉0,8〈/sub〉Co〈sub〉0,2〈/sub〉O〈sub〉3–δ〈/sub〉 cathode with porosity 25 vol%.〈/p〉 〈p〉The experimental characterization was done at two temperature levels: 750 and 800 °C under fixed anodic and cathodic flow and compositions. The preliminary studies on the application of high-pressure injection molding are discussed together with the advantages of the technology. The performance of two generations of anode-supported cells is compared with data of reference cells with supports obtained using tape casting.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 19 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy, Volume 44, Issue 35〈/p〉 〈p〉Author(s): Tian-Feng Hou, Arunkumar Shanmugasundaram, Mostafa Afifi Hassan, Muhammad Ali Johar, Sang-Wan Ryu, Dong-Weon Lee〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In present work, we report a facile fabrication process to improve the photoelectrochemical (PEC) performance of ZnO-based photoelectrodes. In order to achieve that, the Cu〈sub〉2〈/sub〉O nanocubes are cathodic-deposited on the as-prepared ZnO nanorods. Then rGO nanosheets are electrodeposited on the ZnO/Cu〈sub〉2〈/sub〉O heterostructures. The fabricated photoelectrodes are systematically studied in detail by different characterization techniques such as powder X-ray diffraction, micro-Raman, X-ray photoelectron spectroscopy, ultraviolet diffused reflectance spectroscopy and photoluminescence spectroscopy analysis. Morphologies of the fabricated photoelectrodes are investigated through electron microscopy in scanning and transmission mode. To evaluate the PEC performance of the fabricated photoelectrodes, the line scan voltammetry (LSV) measurement is performed using a three-electrode system in 0.5-M Na〈sub〉2〈/sub〉SO〈sub〉4〈/sub〉 electrolyte solution under stimulated light illumination at 100 mW/cm〈sup〉2〈/sup〉 from a 300-W Xenon Arc lamp coupled with an AM 1.5G filter using a three-electrode system. The photocurrent measurement demonstrates that the photoelectrodes based on ZnO/Cu〈sub〉2〈/sub〉O/rGO possess enhanced PEC performance compared to the pristine ZnO and ZnO/Cu〈sub〉2〈/sub〉O photoelectrodes. The photocurrent density of ZnO/Cu〈sub〉2〈/sub〉O/rGO-15 photoelectrode (10.11 mA/cm〈sup〉2〈/sup〉) is ∼9 and ∼3 times higher than the photoelectrodes based on pristine ZnO (1.06 mA/cm〈sup〉2〈/sup〉) and ZnO/Cu〈sub〉2〈/sub〉O (3.22 mA/cm〈sup〉2〈/sup〉). The enhanced PEC performance of ZnO/Cu〈sub〉2〈/sub〉O/rGO photoelectrode is attributed to the excellent light absorption properties of Cu〈sub〉2〈/sub〉O and excellent catalytic and charge transport properties of rGO. Experimental results reveal that the proposed functional nanomaterials have a great potential in water splitting applications.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉The improved PEC performance of the ZnO/Cu〈sub〉2〈/sub〉O/rGO hybrid photoelectrodes is attributed to (i) excellent crystalline nature of the as-prepared ZnO NRs and Cu〈sub〉2〈/sub〉O nanocubes, (ii) large light absorption property of the Cu〈sub〉2〈/sub〉O nanocubes, (iii) high electrical conduction effect and excellent charge transport property of the rGO nanosheets, (iv) electric effect induced by the heterojunction between the vertically aligned ZnO NRs, Cu〈sub〉2〈/sub〉O nanocubes and rGO nanosheets (Scheme 2) and (v) excellent electron acceptor and passivation layer of rGO. All these factors coupled together contribute to the excellent PEC performance of ZnO/Cu〈sub〉2〈/sub〉O/rGO hybrid based photoelectrodes.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S036031991831646X-fx1.jpg" width="221" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 19 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy, Volume 44, Issue 35〈/p〉 〈p〉Author(s): Masoud Rokni〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Fossil fuels are stored energy during millions of years and we are using it in a rate that new fuels cannot be formed. Renewable energies are not available all the time and there is a need to find ways to store them. One way of storing renewable energies is in fuel form, similar to the fossil fuels and then use this stored fuel whenever needed. The plant design proposed in this paper consists of Dish-Stirling collectors supported by a reversible solid oxide cell acting as a power generator and storage unit, and therefore offering dispatchable power on demand. Further, the system reuses the waste heat for seawater desalination. The present work is an analytical study in which the performance evaluation of a self-sustainable polygeneration system with integrated hydrogen production, power generation, and freshwater production is conducted. An evaluation for selected days, representative for summer, fall, winter and spring in an area with low solar irradiation is studies to investigate the potential of this system to supply 500 kW continuously and simultaneously producing a considerable amount of freshwater. The study shows that the plant can produced hydrogen even in low irradiation winter days together with at least 6500 L of freshwater daily.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 26 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy, Volume 44, Issue 36〈/p〉 〈p〉Author(s): Zhentao Wang, Yanwei Zeng, Chuanming Li, Zhupeng Ye, Yuan Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The electrochemical properties of bi-layered electrolytes GDC(Gd〈sub〉0.1〈/sub〉Ce〈sub〉0.9〈/sub〉O〈sub〉1.95〈/sub〉)/YSZ(Y〈sub〉0.16〈/sub〉Zr〈sub〉0.84〈/sub〉O〈sub〉1.92〈/sub〉), ESB(Er〈sub〉0.4〈/sub〉Bi〈sub〉1.6〈/sub〉O〈sub〉3〈/sub〉)/GDC and ESB/YSZ with different layer thickness fractions in the temperature range from 400 to 800 °C have been investigated by simulating calculations based on a charge transport continuity equation and the characteristic conductivity parameters of YSZ, GDC and ESB. It has been found that the model cells with ESB/GDC and ESB/YSZ bi-layered electrolytes can render a higher maximum power density that increases with the ESB layer thickness than those with GDC/YSZ bi-layered electrolytes in the studied temperature range. While the oxygen partial pressure at the interface of ESB/GDC is much lower than that of ESB/YSZ electrolyte with the same ESB thickness fraction, a higher interfacial oxygen partial pressure than the critical decomposition value of Bi〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 can be achieved in the ESB/YSZ electrolytes even with small YSZ thickness fractions. This result strongly suggests that the ESB/YSZ, instead of ESB/GDC, would be a thermodynamic stable bi-layered electrolyte with high output power density for potential applications in the intermediate to low temperature SOFCs.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 19 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy, Volume 44, Issue 35〈/p〉 〈p〉Author(s): Oliver Posdziech, Konstantin Schwarze, Jörg Brabandt〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The paper describes the development status of Sunfire's reversible solid oxide cell (RSOC) technology. Here, Sunfire is a pioneer in the field of high-temperature electrolysers (HTE) for renewable hydrogen production which can be operated as a fuel cell for power generation in a reverse mode. The maturity of the technology is improved stepwise so that first applications in the field of hydrogen production for industry and electricity storage can be tackled. Three application examples where larger scale prototype has been installed will be discussed: 1) A power-to-power electricity storage based on hydrogen, 2) a RSOC unit that is installed in an iron and steel works, and 3) a pressurized SOEC prototype which will be integrated with a methanation unit. Results show the potentials of the technology in connection with fluctuating renewable energy sources.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 6 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy〈/p〉 〈p〉Author(s): Fengzhan Si, Xiaomin Kang, Victoria F. Mattick, Guodong Fu, Xian-Zhu Fu, Kevin Huang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In order to design and synthesize oxygen reduction reaction catalysts with high activity and low cost, a series of Co–Mn-oxide/C catalysts with different Co:Mn ratios have been prepared using a hydrothermal method applied in sequential steps. The monotonically systematic trends of the catalysts’ phases, morphologies and particle sizes have been verified, and the trending of Mn ions and Co ions in different valence states follows the increasing Co:Mn ratio. Electrochemical performance of the catalysts in oxygen reduction reaction results in a volcano-type trend with an optimal Co:Mn ratio of 3 giving the best performance, which is comparable to that of commercial Pt/C. Lastly, a Koutecky-Levich approach has been employed to deduce the electron transfer values, in an attempt to rationalize their selectivity towards the varying 2 and 4 electron pathways. The systematic research is significant for understanding and designing a new generation of non-noble metal oxygen reduction reaction catalysts.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 19 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy, Volume 44, Issue 35〈/p〉 〈p〉Author(s): Arul Murugan, Marc de Huu, Thomas Bacquart, Janneke van Wijk, Karine Arrhenius, Indra te Ronde, David Hemfrey〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Uptake of hydrogen vehicles is an ideal solution for countries that face challenging targets for carbon dioxide reduction. The advantage of hydrogen fuel cell electric vehicles is that they behave in a very similar way to petrol engines yet they do not emit any carbon containing products during operation. The hydrogen industry currently faces the dilemma that they must meet certain measurement requirements (set by European legislation) but cannot do so due to a lack of available methods and standards. This paper outlines the four biggest measurement challenges that are faced by the hydrogen industry including flow metering, quality assurance, quality control and sampling.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy, Volume 183〈/p〉 〈p〉Author(s): M. Kandidayeni, A. Macias, A. Khalatbarisoltani, L. Boulon, S. Kelouwani〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Proton exchange membrane fuel cell (PEMFC) models are multivariate with different nonlinear elements which should be identified accurately to assure dependable modeling. Metaheuristic algorithms are perfect candidates for this purpose since they do an informed search for finding the parameters. This paper utilizes three algorithms, namely shuffled frog-leaping algorithm (SFLA), firefly optimization algorithm (FOA), and imperialist competitive algorithm (ICA) for the PEMFC model calibration. In this regard, firstly, the algorithms are employed to find the parameters of a benchmark PEMFC model by minimizing the sum of squared errors (SSE) between the measured and estimated voltage for two available case studies in the literature. After conducting 100 independent runs, the algorithms are compared in terms of the best and the worst SSEs, the variance, and standard deviation. This comparison indicates that SFLA marginally outperforms ICA and FOA regarding the best SSE in both cases while it performs 20% and twofold better than other algorithms concerning the worst SSE. Furthermore, the obtained variance and standard deviation by SFLA are much less than the other algorithms showing the precision and repeatability of this method. Finally, SFLA is used to calibrate the model for a new case study (Horizon 500-W PEMFC) with variable temperature.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0360544219312848-egi10RTCKX882H.jpg" width="500" alt="Image 10882" title="Image 10882"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy, Volume 183〈/p〉 〈p〉Author(s): Lifu Li, Zhongbo Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In order to improve the natural gas engine (NGE) fuel economy, a steam direct injection method has been presented in the present study. In this method, exhaust was employed to heat water to produce superheated steam firstly. After that, at the power stroke, steam was injected into the cylinder directly. The potentials for fuel savings by this method are evaluated. First, ideal thermodynamic cycle of steam injected NGE is analyzed. Then, a baseline NGE is modeled and validated through experiments. After that, based on the simulation model, the effects of different steam injection parameters on the NGE performance are discussed, including steam mass, temperature and injected timing. The results show that the NGE fuel economy is significantly improved with steam direct injection. With optimal steam mass, 3.9–5.2% reductions of the NGE brake specific fuel consumption (BSFC) are obtained over different speeds, when steam temperature and injected timing are 550 K and 50 deg, respectively. Steam mass and injected timing have great influences on the NGE BSFC. However, steam mass is limited by pinch point temperature difference of the evaporator and exhaust temperature at the evaporator exit. In addition, steam injected timing is restricted by pressure inside the cylinder.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy, Volume 183〈/p〉 〈p〉Author(s): Vinícius Faria Ramos, Olivert Soares Pinheiro, Esly Ferreira da Costa, Andréa Oliveira Souza da Costa〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Detailed model was proposed in this work for exergy analysis of a real biomass boiler. The model was based on an equilibrium model which uses Gibbs Energy minimization and energy balance to calculate the flue gas composition, the temperature of the furnace and the temperature of the flue gases along the boiler. The exergetic efficiency was calculated by the indirect method, and the exergy destruction in each component of the boiler and each material stream was evaluated. The Gibbs minimization model predicted successfully the complete combustion of the biomass and can be adapted to another thermochemical processes. The exergy analysis results showed that the furnace and the water walls have the higher exergy destruction, accounting for 47% and 30% of the total exergy destruction, respectively. In other parts of the boiler, the exergy destruction was higher in the water and steam flows than in the flue gases, and the results indicate that exergy destruction was higher in streams at lower temperatures. The global exergetic efficiency was 42.47%.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy, Volume 183〈/p〉 〈p〉Author(s): Lin Yang, Xiang Ling, Hao Peng, LuanFang Duan, Xiaoyi Chen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this study, a novel high temperature two-phase closed flat heat pipe receiver is proposed and investigated experimentally. In order to simulate the transient startup from frozen state, a transient analysis code for the novel flat heat pipe receiver has been developed. Closed-form analytical solutions for the temperature distribution along the heat pipe length are obtained and experimental tests are undertaken. These closed-form analytical solutions are in good agreement with the experimental data. The theoretical and experimental studies prove that the flat heat pipe receiver with sodium as working fluid has a well startup performance. Experiments were carried out to investigate the temperature uniformity of FHPR under the normal conditions. It is found that the FHPR has well feature of uniformity and stability through startup process experiments with constant heat flux. This research provides guidance for the research and development of flat heat pipe solar receiver, and has important significance for broadening its application in the field of heat utilization of solar energy at high temperature.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy, Volume 183〈/p〉 〈p〉Author(s): Paweł Ocłoń, Marzena Nowak-Ocłoń, Andrea Vallati, Alessandro Quintino, Massimo Corcione〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This paper presents the determination of the heat losses of the pre-insulated pipe and twin pipe in the heating network. The paper compares the heat losses calculated by using the analytical solution (1D model) and numerical model (2D model) based on the Finite Element Method. The developed numerical model considered undisturbed ground temperature at various depths. Therefore, it allowed to study the effect of temperature distribution at various ground depths on heat losses in heating network. Various variants of insulation are considered including standard, plus and plus-plus types for pre-insulated tubes. The remaining heat loss calculation is based merely on temperature levels and thermal resistance factors (in the ground), determined by the pipe dimensions and materials. The differences in calculated heat losses by analytical and numerical model do not exceed 10%.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy, Volume 183〈/p〉 〈p〉Author(s): Sobhan Badakhshan, Neda Hajibandeh, Miadreza Shafie-khah, João.P.S. Catalão〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Photovoltaic energy is one of the clean and efficient energies which has been developing quickly in the last years. As the penetration of solar plants is increasing in the electricity network, new problems have arisen in network operation. This paper models a high penetration factor of solar energy in the electricity network and investigates the impact of solar energy growth on both the generation schedule of different power plants and in the natural gas transmission network. Fuel management of gas power plants is modeled through simulation of the natural gas transmission network. To this end, an increase in the penetration of solar energy in the electricity network inevitably leads to a sudden increase in the output of gas fired units and a linear and integrated model with the electricity and the natural gas transmission networks has been presented to analyze both of them at the same time to better depict the impact of a high penetration of the solar energy in natural gas transmission grids. In this method, natural gas transmission network and Security Constrained Unit Commitment (SCUC) are presented in a single level program. Gas network constraints are linearized and added to the SCUC problem. The stress imposed on the gas network due to a sudden increase in the load of the electricity network is investigated. Conclusions are duly drawn.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy, Volume 183〈/p〉 〈p〉Author(s): Bin Zhao, Mingke Hu, Xianze Ao, Nuo Chen, Qingdong Xuan, Yuehong Su, Gang Pei〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉For rooftop building-integrated photovoltaic (BIPV) technology, photovoltaic (PV) modules are typically mounted on the sunny side of a rooftop to receive a high amount of solar irradiance, whereas the opposite side of the rooftop will have free space. This study proposed a novel strategy for building-integrated PV and radiative cooling (RC) system, namely BIPV−RC system, by covering the sunny side of a rooftop with PV modules and its free side with all-day RC modules to integrate solar energy collection and RC utilization into a single building unit. A mathematical model was developed for the proposed BIPV−RC system and a case study was conducted in two tropical cities (Karachi, Pakistan and Riyadh, Saudi Arabia). Results show the total electricity and cooling output of the BIPV−RC system in Riyadh is 462.1 kWh·m〈sup〉−2〈/sup〉 and 1315.3 MJ m〈sup〉−2〈/sup〉, respectively, approximately 20.7% and 94.0% higher than those in Karachi. Moreover, a comparative study between the BIPV−RC system and the common BIPV and building-integrated RC (BIRC) system was performed and results indicate that the annual total energy output of the BIPV−RC system is nearly 79.1% and 16.8% higher than that of BIPV and BIRC system, respectively.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy, Volume 183〈/p〉 〈p〉Author(s): Yuanwang Deng, Changling Feng, Jiaqiang E, Kexiang Wei, Bin Zhang, Zhiqing Zhang, Dandan Han, Xiaohuan Zhao, Wenwen Xu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Hydrocarbon(HC) emission from cold start for gasoline engine has become a big problem as the emission regulations go increasingly stringent. Zeolites are used to reduce hydrocarbon emission from gasoline engine before three-way catalysts reaching its operating temperature. In this paper, a mathematical model is fitted from hydrocarbons emission experimental data and a computational fluid dynamic(CFD) method is applied to investigate the influence on adsorption capacity of the different gasoline engine hydrocarbons catchers, and grey relational analysis is used to analyze and enhance adsorption performance of the gasoline engine hydrocarbon catchers for reducing hydrocarbons emission during the cold-start period. Driving cycle Federal Test Procedure(FTP) 75 is adopted to see the transient response of adsorbing hydrocarbon in cold start period. Results show that both hydrocarbon catcher length and its zeolite type in gasoline engine have great impact on hydrocarbon adsorption, the ranking of adsorption capacity is 25 cm  〉  20 cm  〉  15 cm, 5A 〉 13X. The gasoline engine hydrocarbon catcher with 25 cm length using zeolite 5A is of the best adsorption performance, and with this hydrocarbon catcher, the adsorption efficiency is 35.8% under cold start for driving cycle FTP75.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 6 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy〈/p〉 〈p〉Author(s): Pragati Singh, Pardeep K. Jha, Priyanka A. Jha, Prabhakar Singh〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Sodium bismuth titanate samples with different morphology were synthesized via varying the sintering temperature from 1000 to 1150 °C. The conductivity was significantly affected with the morphology of the system. The dynamics of ions was understood from the conductivity spectra. The dc conductivity, hopping frequency and exponent values were extracted from the conductivity spectra analysis. The impedance and modulus spectroscopy along with exponent behaviour suggested short range hopping for the sample sintered at 1000 °C and followed Ghosh scaling instead of Summerfield scaling. While long-range hopping was observed for the samples sintered at 1150 °C and it followed both the Summerfield scaling and Ghosh scaling. Moreover, the stability of the sample is checked in reducing atmosphere.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0360319919323468-fx1.jpg" width="280" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 6 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy〈/p〉 〈p〉Author(s): Ruirun Chen, Xin Ding, Xiaoyu Chen, Xinzhong Li, Yanqing Su, Jingjie Guo, Hongsheng Ding, Hengzhi Fu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Nanosizing is efficient as the dual-tuning of thermodynamics and kinetics for Mg-based hydrogen storage materials. The in-situ synthesis of nanocomposites through hydrogen-induced decomposition from long-period stacking ordered phase is proved effective to achieve active nano-sized catalysts with uniform dispersion. In this study, the Mg〈sub〉93〈/sub〉Cu〈sub〉7-〈em〉x〈/em〉〈/sub〉Y〈sub〉〈em〉x〈/em〉〈/sub〉 (〈em〉x〈/em〉 = 0.67, 1.33, and 2) alloys with equalized Mg–Mg〈sub〉2〈/sub〉Cu eutectic and 14H long-period stacking ordered phase of Mg〈sub〉92〈/sub〉Cu〈sub〉3.5〈/sub〉Y〈sub〉4.5〈/sub〉 are prepared. Its solidification path is determined as α-Mg, 14H–Mg〈sub〉2〈/sub〉Cu pair and Mg–Mg〈sub〉2〈/sub〉Cu eutectic. The increased Y/Cu atomic ratio lowers the first-cycle hydrogenation rate of the alloys due to the increased 14H–Mg〈sub〉2〈/sub〉Cu structure and reduced Mg–Mg〈sub〉2〈/sub〉Cu eutectic interfaces. After the hydrogen-induced decomposition of the long-period stacking ordered phase, MgCu〈sub〉2〈/sub〉 and YH〈sub〉3〈/sub〉 nanoparticles are in-situ formed, and the following activation process significantly accelerates. The YH〈sub〉3〈/sub〉 nanoparticles partly decompose to YH〈sub〉2〈/sub〉 at 300 °C in vacuum and Mg–Mg〈sub〉2〈/sub〉Cu-YH〈sub〉〈em〉x〈/em〉〈/sub〉 nanocomposites are in-situ formed. The nano-sized YH〈sub〉2〈/sub〉 helps catalyze H〈sub〉2〈/sub〉 dissociation and the YH〈sub〉〈em〉x〈/em〉〈/sub〉/Mg interfaces stimulate H diffusion and the nucleation of MgH〈sub〉2〈/sub〉. Therefore, the Mg〈sub〉93〈/sub〉Cu〈sub〉5〈/sub〉Y〈sub〉2〈/sub〉 composite shows the fastest absorption rates. However, due to the positive effect of YH〈sub〉〈em〉x〈/em〉〈/sub〉/Mg interfaces on H diffusion and the negative effect of YH〈sub〉3〈/sub〉 nanophases on the hydride decomposition, the minimum activation energy of 115.43 kJ mol〈sup〉−1〈/sup〉 is obtained for the desorption of the Mg〈sub〉93〈/sub〉Cu〈sub〉5.67〈/sub〉Y〈sub〉1.33〈/sub〉 hydride.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0360319919323390-fx1.jpg" width="343" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 6 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy〈/p〉 〈p〉Author(s): Zhihao Dong, Tong Zhou, Jie Liu, Xinwen Zhang, Bin Shen, Wenbin Hu, Lei Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Stainless steels as proton exchange membrane fuel cell bipolar plates have received extensive attention in recent years. The pack chromizing layer was fabricated on 316L stainless steel to improve the corrosion resistance and electrical conductivity. The corrosion properties were investigated in 0.5 M H〈sub〉2〈/sub〉SO〈sub〉4〈/sub〉 + 2 ppm HF solution at 70 °C purged with hydrogen gas and air. Higher electrochemical impedance and more stable passive film were obtained by chromizing the 316L stainless steel. Potentiodynamic polarization results showed the corrosion current densities were reduced to 0.264  μA cm〈sup〉−2〈/sup〉 and 0.222  μA cm〈sup〉−2〈/sup〉 in two simulated operating environments. In addition, the interfacial contact resistance was decreased to 1.4 mΩ⋅cm〈sup〉2〈/sup〉 under the compaction force of 140 N⋅cm〈sup〉−2〈/sup〉 and maintained at low values after potentiostatic polarization for 4 h. The excellent corrosion and conductive performances could be attributed to the chromium carbides and high alloying element content in chromizing layer.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0360319919323493-fx1.jpg" width="278" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 6 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy〈/p〉 〈p〉Author(s): Anshul Gupta, Suboohi Shervani, Flamina Amaladasse, Sri Sivakumar, Kantesh Balani, Anandh Subramaniam〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Nickel is a good catalyst for the dissociation of molecular hydrogen to atomic form, but suffers from a negligible hydrogen storage capacity (∼10〈sup〉−4〈/sup〉 wt% at 25 °C and 1 atm). The current investigation pertains to the enhancement in the reversible hydrogen storage capacity of Ni via storage in molecular form; thus utilizing a recently developed multi-mode storage philosophy. Ni nano hollow spheres (NiHS) have been synthesized using hydrothermal method (outer diameter of ∼300 nm and shell thickness ∼30 nm). Pressure-composition-isotherms and temperature programmed desorption curves have been used to characterize the hydrogen storage capacity and to establish the reversibility of the process. An enhancement in the reversible storage capacity by a factor of 7 × 10〈sup〉3〈/sup〉 (7,00,000%) is obtained at 25 °C and 150 bar pressure. The capacity is further enhanced to 0.91 wt% hydrogen by utilizing a pressure of 300 bar. Ni plays a dual catalytic role in the absorption and desorption process.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 6 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy〈/p〉 〈p〉Author(s): Xiaoqiang Du, Hui Su, Xiaoshuang Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The efficiency and stability of electrocatalysts are the key factors for measuring oxygen evolution reaction. In this work, the MnCo〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 structure assembled from well-arranged nanowires or nanosheet arrays has been grown vertically on nickel foam by in-situ hydrothermal method. Interestingly, different morphology of MnCo〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 can be easily regulated by adding NH〈sub〉4〈/sub〉F to a mixed solvent to achieve conversion from nanowires to nanosheets. In addition, further synthesis of unique three-dimensional hierarchical core/shell MnCo〈sub〉2〈/sub〉O〈sub〉4〈/sub〉@CoS nanowires or nanosheets arrays was performed primarily by electrochemical deposition. Both MnCo〈sub〉2〈/sub〉O〈sub〉4〈/sub〉@CoS-7 cycles nanowires and MnCo〈sub〉2〈/sub〉O〈sub〉4〈/sub〉@CoS-7 cycles nanosheets exhibit high efficiency and long-lasting stability for the oxygen oxidation reaction. The lower overpotential of only 280 mV and 270 mV at 20 mA cm〈sup〉−2〈/sup〉 for the MnCo〈sub〉2〈/sub〉O〈sub〉4〈/sub〉@CoS-7 cycles nanowires and MnCo〈sub〉2〈/sub〉O〈sub〉4〈/sub〉@CoS-7 cycles nanosheets were obtained with lower Tafel slopes of 139. 19 mV dec〈sup〉−1〈/sup〉 and 131.81 mV dec〈sup〉−1〈/sup〉 in 1.0 M potassium hydroxide respectively comparing with our other MnCo〈sub〉2〈/sub〉O〈sub〉4〈/sub〉@CoS catalysts. The results demonstrate that the crystal morphology of MnCo〈sub〉2〈/sub〉O〈sub〉4〈/sub〉@CoS does not significantly influence their electrocatalytic activity in water oxidation reactions by comparing nanostructured MnCo〈sub〉2〈/sub〉O〈sub〉4〈/sub〉@CoS nanowires and MnCo〈sub〉2〈/sub〉O〈sub〉4〈/sub〉@CoS nanosheets. The high catalytic activity of the MnCo〈sub〉2〈/sub〉O〈sub〉4〈/sub〉@CoS nanoarrays is attributed to the possession of more active sites, larger specific surface area, abundant oxygen vacancy, and fast electron transport rate. Not only that, the durability of the MnCo〈sub〉2〈/sub〉O〈sub〉4〈/sub〉@CoS nanoarrays is also excellent after continuous oxygen evolution test of 1000 cycles. The results of XRD, SEM and XPS show that MnCo〈sub〉2〈/sub〉O〈sub〉4〈/sub〉@CoS-7 cycles nanowires and MnCo〈sub〉2〈/sub〉O〈sub〉4〈/sub〉@CoS-7 cycles nanosheets materials can be used as a highly efficient and stable catalyst for oxygen evolution reaction.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉The results of XRD, SEM and XPS show that MnCo〈sub〉2〈/sub〉O〈sub〉4〈/sub〉@CoS-7 cycles nanowires and MnCo〈sub〉2〈/sub〉O〈sub〉4〈/sub〉@CoS-7 cycles nanosheets materials can be used as a highly efficient and stable catalyst for oxygen evolution reaction.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0360319919323365-fx1.jpg" width="308" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy, Volume 183〈/p〉 〈p〉Author(s): Guihua Zhu, Lingling Wang, Naici Bing, Huaqing Xie, Wei Yu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The working fluids with higher solar thermal conversion performance within broadband spectrum ranges are of great concern for direct absorption solar collectors (DASCs). Both metal nanoparticles with localized surface plasmon resonance (LSPR) effects and carbon nanomaterials have unique spectral absorption behaviors and have shown better photothermal performance in DASCs. In this paper, we attempted to prepare composite nanofluids including plasmonic bimetallic alloy and carbon nanomaterials to realize enhanced solar absorption and photothermal conversion performance. By taking ZIF-8-derived nitrogen-doped graphitic polyhedrons (ZNGs) as carrier, plasmonic bimetallic Ag-Au alloy nanoparticles were loaded on them by an impregnation-reduction method successfully. Ag-Au/ZNGs ethylene glycol nanofluids showed significant broadband absorption in the visible and near-infrared spectrum range at a lower concentration. Comparing to ethylene glycol, the photothermal conversion effeiency of all ZNGs nanofluids increased remarkablely. Plasmonic bimetallic Ag-Au alloy nanoparticles further improved the photothermal conversion efficiency, which was up to 74.35% for Ag-Au ZNGs nanofluids compared with 72.41%, 70.35% for Au/ZNGs, Ag/ZNGs respectively. This work presents a new way to enhance solar energy absorption and improve solar thermal conversion efficiency of nanofluids for DASCs.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy, Volume 183〈/p〉 〈p〉Author(s): Ruipeng Tan, Boqiang Lin, Xiying Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Market-oriented reforms on production factors in China are far lagged behind that of the commodity market, remaining the problem of price distortion in production factor markets. In this paper, we measure the degree of relative price distortion among capital, labor and energy focusing on China's secondary industry. Then, we take the own-price and cross-price elasticities as the link to estimate the demand changes of the three production factors in three cases. At last, we estimate the influence of relative price distortion elimination on the total factor energy efficiency. The main findings are: relative price distortions among the three factors exist. No matter taking the prices of capital, energy or labor as the benchmark, the prices of the other two kinds of production factors should be changed. Second, the own-price elasticities of the factors are negative, while the cross-price elasticities between the factors are positive, indicating the substitutability among the factors. Finally, correcting the relative price distortion can serve for the improvement of total factor energy efficiency of China's secondary industry. Therefore, if taking improvement of total factor energy efficiency as the goal, eliminating the price distortion in the factor market is necessary.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy, Volume 183〈/p〉 〈p〉Author(s): Honglun Yang, Qiliang Wang, Yihang Huang, Junsheng Feng, Xianze Ao, Maobin Hu, Gang Pei〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Solar selective absorbing coatings that absorb solar irradiation and emit infrared radiation have a significant impact on the thermal efficiency of the receivers. The spectrum parameters heat transfer model and the non-ideal coating curve model are established. The cutoff wavelength of coatings is comprehensively optimized, and the effect of the optical properties of the coating on overall performance is analyzed. Results show that the optimal cutoff wavelength rises with the solar irradiation flux but decreases with increased absorber temperature. Sensitivity analysis results of the coating optical properties indicates that the thermal efficiency significantly decreases with increasing slope width. The change range of the thermal efficiency at the temperature of 200 °C is ±0.1%, resulting from a ±1 μm variation in slope width, whereas the range at 600 °C is ±6.5%. Spectral absorptivity analysis shows that the coating absorptivity has nearly same positive influence on thermal efficiency under different temperatures and irradiation fluxes, whereas emissivity analysis reveals an evidently different negative effect on the receiver performance. Finally, the annual optimal cutoff wavelength decreases with increasing temperature but increases with solar irradiation. The optimal cutoff wavelength decreases from 2.23 μm at 200 °C to 0.78 μm at 600 °C in Phoenix.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy, Volume 183〈/p〉 〈p〉Author(s): Jing Yang, Zhiyong Zhang, Mingwan Yang, Jiayu Chen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Recovering wasted heat is sustainable and cost-effective approach to secure energy supply in cities. This paper extended the Stackelberg game model to investigating the supply chain of the waste heat recovery market. Three models were proposed to investigate the optimal decision-making for different supply chain participants. With a validation case, the results suggested that the joint decision can reach the optimal outcomes and cost. Mobile heating strategy has advantages over coal-fired boilers, electric boilers, natural gas boilers in terms of costs and environmental protection. With a typical consumption of the recovered waste heat 342 GJ/day for water heating (from 25 °C to 60 °C) can save 11.672t standard coal and 79,800 RMB per day. In addition, improving thermal energy quality of waste heat recovery can generate higher profit and attract more potential customers.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy, Volume 183〈/p〉 〈p〉Author(s): Xiaotian Lai, Minjie Yu, Rui Long, Zhichun Liu, Wei Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A modified theoretical model of dish solar Stirling engine was developed based on a Stirling cycle operating with finite shaft rotating speed and the energy balance equations at hot and cold ends. The convergence of solar receiver temperature and charged gas heat releasing temperature represent the stabilization of solar receiver and Stirling engine respectively, thus, to guarantee a steady operation of the overall system. Impacts of meteorological condition, operational parameter of Stirling engine on system performance were investigated and analyzed systematically. Results indicate that higher solar flux intensity improves system performance while wind deteriorates the system performance. With the input solar energy specified, optimal charged gas mass in Stirling engine exists corresponding to the maximal power output. More effective heater, regenerator and cooler contribute to better optimal system performance. Meanwhile, the charged gas mass optimized under the daily average solar flux intensity achieves the maximal mechanical work in a day with less computation. The maximal theoretical peak power output of 25 kW and overall efficiency of 44% are obtained as high performance heat exchangers are adopted and charged gas mass is optimized.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 12 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy, Volume 44, Issue 34〈/p〉 〈p〉Author(s): Arzu Kanca, Deniz Uner〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Economical valorization of low quality, high sulfur feedstocks is an important challenge. Most of the valorization processes start from pyrolysis, with a significant amount of evolution of sulfur containing compounds. This study addresses in situ and downstream sulfur capture ability of lead oxide (PbO) in comparison to zinc oxide (ZnO) during the pyrolysis of high–sulfur Tuncbilek lignite. In order to assess the role of hydrogen in sulfur capture, hydrogenation experiments were also performed. Sulfidation reaction thermodynamics of PbO and ZnO was compared to most commonly used metal oxides for sulfur capture i.e., FeO, MnO, and CaO. The equilibrium conversions indicated superior performance of PbO and ZnO towards sulfidation reactions at high temperatures. Thermodynamic superiority of PbO sulfidation encouraged us to investigate the PbO as a new sulfur sorbent for hot gas desulfurization. The experimental verification of the high temperature sulfidation ability of PbO and ZnO was performed using high–sulfur Tuncbilek lignite under semibatch conditions. The final compounds formed after each process were observed by X-ray diffractometer (XRD) and Diffuse Reflectance Infrared Fourier Transformation Spectroscopy (DRIFTS). Experiments revealed that PbO can be promising candidate as hot gas sulfur trap during pyrolysis and hydrogenation processes, while ZnO can hold up sulfur only in the presence of hydrogen. Furthermore, both PbO and ZnO show the superior sulfur capture performance in the presence of hydrogen when they were used as adsorbents located after the reactor (downstream) at ambient conditions.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 12 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy, Volume 44, Issue 34〈/p〉 〈p〉Author(s): Mustafa Kaan Baltacioglu, Raif Kenanoglu, Kadir Aydın〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉One of the primary aims of this experimental investigation is to examine hydroxy-gas enrichment effects on environmentally friendly but performance-reducing alternative fuels such as ethanol and biodiesel. Hydroxy gas is a product of the pure water electrolysis method. Entire HHO system has integrated into engine test rig for this purpose. Two different biodiesohol fuel blend prepared and named by their volumetric compositions. Biodiesohol used to describe biodiesel, ethanol and standard diesel blends. Specific fuel properties are measured and ensured to be in EN590 and EN14214 standards. Experiments were conducted on a single cylinder diesel engine which was fuelled with diesel-biodiesel-ethanol fuel blends those enriched by 1 L per minute HHO gas during the entire tests. All of the experiments performed under full load condition within the range of 1200–3200 rpm engine speed. From the view of performance; brake power, brake specific fuel consumption and thermal efficiency results discussed. Besides, carbon monoxide and nitrogen oxides results measured and presented as exhaust emission. Standard diesel fuel outputs determined as a reference line to analyze the changes. A number of studies have been conducted with fuels used in this experimental study and their mixture in different ratios as well, but an examination of the HHO addition to biodiesel is performed for the first time in this research area of the literature.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 12 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy, Volume 44, Issue 34〈/p〉 〈p〉Author(s): Yusuf Bicer, Ibrahim Dincer〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The study presented here concerns a comprehensive investigation on exergoeconomic analysis and optimization of an integrated system for photoelectrochemical hydrogen and electrochemical ammonia production. The present integrated system consists of a solar concentrator, spectrum-splitting mirrors, a photoelectrochemical hydrogen production reactor, a photovoltaic module, an electrochemical ammonia production reactor and support mechanisms. Detailed thermodynamic and exergoeconomic analyses are initially conducted to determine the performance of the integrated system namely; efficiency and total cost rate. The obtained performance parameters are then optimized to yield the minimum cost rate and maximum efficiency under given constraints of the experimental system. The highest capital cost rates are observed in the photoelectrochemical hydrogen and electrochemical ammonia production reactors because of high procurement costs and electricity inputs. The optimized values for exergy efficiency of the integrated system range from 5% to 9.6%. The photovoltaic and photoelectrochemical cell areas and solar light illumination mainly affect the overall system efficiencies. The optimum efficiencies are found to be 8.7% and 5% for the multi-objective optimization of hydrogen production and integrated ammonia production system, respectively. When the exergy efficiency of the integrated system is maximized and the total cost rate is minimized at the same time, the total cost rate of the system is calculated to be about 0.2 $/h. The cost sensitivity analysis results of the present study show that the total cost rate of the system is mostly affected by the interest rate and lifetime of the system.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0360319918332518-fx1.jpg" width="266" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 12 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy, Volume 44, Issue 34〈/p〉 〈p〉Author(s): Gobeng R. Monama, Kwena D. Modibane, Kabelo E. Ramohlola, Kerileng M. Molapo, Mpitloane J. Hato, Mogwasha D. Makhafola, Gloria Mashao, Siyabonga B. Mdluli, Emmanuel I. Iwuoha〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Copper(II)phthalocyanine-incorporated metal organic framework (CuPc/MOF) composite material was synthesized for application as an electrocatalyst for hydrogen evolution reaction (HER). The composite exhibited excellent electroactivity compared to the unmodified MOF, as confirmed by the diffusion coefficients (〈em〉D〈/em〉) values of 3.89 × 10〈sup〉−7〈/sup〉 and 1.57 × 10〈sup〉−6〈/sup〉 cm〈sup〉2〈/sup〉 s〈sup〉−1〈/sup〉 for MOF and CuPc/MOF, respectively. The 〈em〉D〈/em〉 values were determined from cyclic voltammetry (CV) experiments performed in 0.1 mol L〈sup〉−1〈/sup〉 tetrabutylammonium perchlorate/dimethyl sulfoxide (TBAP/DMSO) electrolyte. The Tafel slope determined from the CV data of CuPc/MOF-catalysed HER for 0.450 mol L〈sup〉−1〈/sup〉 H〈sub〉2〈/sub〉SO〈sub〉4〈/sub〉, was 176.2 mV dec〈sup〉−1〈/sup〉, which was higher than that of the unmodified MOF (158.3 mV dec〈sup〉−1〈/sup〉). The charge transfer coefficients of MOF and CuPc/MOF were close to 0.5, signifying the occurrence of a Volmer reaction involving either the Heyrovsky or the Tafel mechanism for hydrogen generation. For both MOF and CuPc/MOF, the exchange current density (〈em〉i〈/em〉〈sub〉0〈/sub〉) improved with increase in the concentration of the hydrogen source (i.e. 0.033–0.45 mol L〈sup〉−1〈/sup〉 H〈sub〉2〈/sub〉SO〈sub〉4〈/sub〉) Nonetheless, the CuPc/MOF composite had a higher 〈em〉i〈/em〉〈sub〉0〈/sub〉 value compared with the unmodified MOF. Thus CuPc/MOF has promise as an efficient electrocatalyst for HER.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 12 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy, Volume 44, Issue 34〈/p〉 〈p〉Author(s): Ramazan Solmaz, Hilmi Yurdakul〈/p〉

Description: 〈p〉Publication date: 15 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy, Volume 183〈/p〉 〈p〉Author(s): Yu-Jen Wang, Chih-Kuang Lee〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this study, a two-degree-of-freedom (2-DOF) wave energy converter (WEC) composed of an eccentric dual-axis ring and power generators using circular Halbach array magnetic disks and iron-core coils was developed. The 2-DOF WEC was designed to convert kinetic energy from the pitching, rolling, and heaving motions of a mooring-less buoy. The eccentric dual-axis ring with appropriate weighting conditions enhanced power generation by revolving in biaxial hula-hoop motion, because it exhibited a higher angular velocity than when in swing motion. Kinetic equations for the biaxial eccentric dual-axis ring mounted on the buoy were derived using the Lagrange–Euler equation. Furthermore, weighting conditions of the eccentric dual-axis ring for biaxial hula-hoop motion were determined in accordance with frequency and amplitude of regular buoy motion. The magnetic flux density, cogging torque, and electromagnetic damping of the magnetic disk were evaluated using magnetic field strength simulations and Faraday's law of induction. The 2-DOF WEC prototype was implemented, and biaxial hula-hoop motion was observed in a wave flume test. An output power of 0.56 W was generated for the primary frequency of buoy motion from 0.7 to 1.0 Hz. Results indicate the WEC is feasible as a sustainable power source for sensors on buoys.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy, Volume 183〈/p〉 〈p〉Author(s): Juan Ignacio Peña, Rosa Rodríguez〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This paper studies the realizability and compatibility of the three CEP2020 targets, focusing on electricity prices. We study the impact of renewables and other fundamental determinants on wholesale and household retail electricity prices in ten EU countries from 2008 to 2016. Increases in production from renewables decrease wholesale electricity prices in all countries. As decreases in prices should promote consumption, an apparent contradiction emerges between the target of an increase in renewables and the target of a reduction in consumption. However, the impact of renewables on the non-energy part of household wholesale electricity prices is positive in six countries. Therefore, decreases in wholesale prices, that may compromise the CEP2020 target of decrease in consumption, do not necessarily translate into lower household retail prices. Monte Carlo simulations suggest that the probability of achieving CEP's target of reductions in GHG emissions for 2020 is lower than 1% in Austria, Portugal, and Spain. In horizon 2030, Austria, France, Germany, Portugal, and Spain have probabilities lower than 1% of achieving the GHG emissions target. Finland and France present success probabilities lower than 1% on the national targets of renewable sources for 2020 and 2030 as do Austria and Spain with reductions in electricity consumption.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 29 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy〈/p〉 〈p〉Author(s): Prashant Sharma, Sandeep Gupta, Rini Singh, Kanad Ray, S.L. Kothari, Soumendu Sinha, Rishi Sharma, Ravindra Mukhiya, Kamlendra Awasthi, Manoj Kumar〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In the present paper, Na〈sub〉3〈/sub〉BiO〈sub〉4〈/sub〉–Bi〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 films have been tested for hydrogen ion sensing. Na〈sub〉3〈/sub〉BiO〈sub〉4〈/sub〉–Bi〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 mixed oxide nanostructures were deposited on the Indium–Tin-Oxide (ITO) coated glass substrate using a low-cost electrodeposition technique at room temperature. The nanostructures have been characterized using FESEM and XPS to study their morphology and composition, respectively. Vertically aligned nanostructures (thickness~90 nm) with well-defined edges were seen in FESEM studies. XPS analysis indicates the presence of Na〈sub〉3〈/sub〉BiO〈sub〉4〈/sub〉 and Bi〈sub〉2〈/sub〉O〈sub〉3〈/sub〉. The crystallinity and the mixed phase of the film were further confirmed by X-ray diffraction study. These nanostructures were explored as a potential candidate for pH sensing using them as a sensing film for Extended-Gate Field-Effect Transistor (EGFET). A sensitivity of 49.63 mV/pH has been observed with good linearity. To the best of our knowledge, for the first time vertically aligned Na〈sub〉3〈/sub〉BiO〈sub〉4〈/sub〉–Bi〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 mixed oxide nanostructures are demonstrated as an EGFET-based (Hydrogen ion) pH sensor.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 29 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy〈/p〉 〈p〉Author(s): Yang Zhang, Tian Zhang, Zhiping Zhang, Nadeem Tahir, Quanguo Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉As a perennial grass, 〈em〉Humulus scandens〈/em〉 is rich in cellulose which can be fermented for bioenergy producing. Hence, the hydrogen production potential of the 〈em〉Humulus scandens〈/em〉 from dark fermentation by 〈em〉Enterobacter aerogenes〈/em〉 was investigated in this paper. Cellulase amount, inoculation amount, and initial pH value were evaluated. The interrelationship between these factors were studied by Response Surface Box-Behnken Experiments. Results showed that there was a significant correlation between the three factors. Through the correction of the regression equation, the optimized technological conditions were obtained. The amount of cellulase was 0.203 g g〈sup〉−1〈/sup〉 TS, the inoculation amount was 42.6%, the initial pH value was 6.59, the pre-estimated maximum cumulative value of hydrogen production was 65.12 mL g〈sup〉−1〈/sup〉 TS, and it was similar to the test mean value which was 64.08 mL g〈sup〉−1〈/sup〉 TS.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 29 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy〈/p〉 〈p〉Author(s): Harun Yilmaz〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Major challenges for micro combustors are high heat losses and inappropriate residence time. In this study, it was aimed to eliminate these challenges via placing bluff bodies into the combustion zone and combusting fuel with oxygen enriched air. To this end, micro combustor models with different geometries were constructed and in these models, premixed H〈sub〉2〈/sub〉/air combustion was simulated by using ANSYS/Fluent CFD code to investigate effects of bluff body shape, location and thickness, and low level O〈sub〉2〈/sub〉 enhancement on performance determining parameters such as rate of conversion of fuel to useable heat, temperature uniformity, pollutant emissions etc. To further analyze effects of micro combustor geometry, a perforated plate was also placed into the combustion zone. Thermal performance of the micro combustor with perforated plate insertion in O〈sub〉2〈/sub〉 enriched conditions was found to be highest in terms of increased reaction kinetics and heat transfer characteristics. The trade-offs of respective design are increased NO〈sub〉x〈/sub〉 emissions and slightly decreased temperature uniformity.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 29 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy〈/p〉 〈p〉Author(s): Sujoy Bepari, Debasish Kuila〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Depletion of non-renewable energy sources such as coal and natural gas is paving the way to generate alternative energy sources. Hydrogen, a very promising alternative energy has the highest energy density (143 MJ/kg) compared to any known fuel and it has zero air pollution due to the formation of water as the only by-product after combustion. Currently, 95% of hydrogen is produced from non-renewable sources. Hydrogen production from renewable sources is considered a promising route for development of sustainable energy production. Steam reforming of renewable sources such as methanol, ethanol and glycerol is a promising route to hydrogen production. This review covers steam reforming of these three alcohols using Ni-based catalysts with different supports. Chemistry of the steam reforming reactions is discussed. Hydrogen yield depends on operating conditions, the nature of active metal and the catalyst support. Supports play an important role in terms of hydrogen selectivity and catalyst stability because of their basic characteristics and redox properties. Synthesis of suitable catalysts that can suppress coke formation during reforming is suggested.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 29 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy〈/p〉 〈p〉Author(s): Sandeep Kumar Lakhera, V.S. Vijayarajan, B.S. Rishi Krishna, Pandiyarasan Veluswamy, Bernaurdshaw Neppolian〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉To overcome the low photocatalytic efficiency of bulk g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉, herein, we have designed a novel cobalt phosphate hydroxide loaded graphitic carbon nitride photocatalysts by co-precipitation route. The FESEM and HRTEM analysis revealed that in the presence of the phosphorus compound, the g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉 sheets tend to fold and form a rod-like morphology. The loading of cobalt phosphate hydroxide in g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉 resulted in the redshift of the absorption edge. XRD, FTIR and XPS analysis revealed that cobalt phosphate hydroxide is bonded to g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉 via electrostatic interaction. The cobalt phosphate hydroxide/g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉 photocatalysts was used for photocatalytic hydrogen evolution and produced nearly 1016 μmol/g of hydrogen in 4 h of reaction time under direct solar light irradiation. This significantly higher activity was accredited to the effective charge carrier separation by cobalt phosphate hydroxide in the photocatalysts, as shown by the photoluminescence and time-resolved photoluminescence (TRPL) measurements. TRPL measurements have shown that Co〈sub〉2〈/sub〉PO〈sub〉4〈/sub〉OH incorporation in g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉 leads to a 42% higher lifetime of photogenerated charge carriers. In addition, the Co〈sub〉2〈/sub〉PO〈sub〉4〈/sub〉OH loaded g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉 photocatalysts retains its photostability even after four cycles of reaction without any significant drop in hydrogen production activity. This work provides a facile approach to synthesize highly stable and efficient visible light active cobalt phosphate hydroxide loaded graphitic carbon nitride photocatalysts for solar energy conversion applications.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0360319919328381-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 10 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy〈/p〉 〈p〉Author(s): Xinming Du, Hongyu Zhang, Minghui Li, Zhe Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The alternating copolymer based on poly (ether ether ketone) (PEEK) is synthesized with ordered side chain. A series of novel anion exchange membranes grafte with the 1, 2-dimethylimidazole and 1-vinylimidazole are obtained. The copolymer was verified by 〈sup〉1〈/sup〉H NMR and the crosslinked membranes are further investigated by solvability test. The ordered hydrophilic side chains form well-defined microphase separation structure, which are proved by Transmission electron micrographs microscopy (TEM). The ionic conductivity is 0.075 S/cm at 80 °C of Im-PEEK-0 uncross-linked membrane. With the addition of 1-vinylimidazole, the maximum stress increases to 66.57 MPa, the water uptake drop to 17.1% and swelling ratio drop to 14.8% at 80 °C of Im-PEEK-0.3 membrane. The hydroxide conductivity remains 82.8% in 2 mol L〈sup〉−1〈/sup〉 NaOH solution at 60 °C for 400 h. Meanwhile, all the membranes exhibit excellent thermal stability. Overall, the ordered imidazolium-functionalized side chains provide a method to balance hydroxide conductivity and alkali stability of anion exchange membranes.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 9 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy〈/p〉 〈p〉Author(s): Vikrant Yadav, Abhishek Rajput, Nehal H. Rathod, Vaibhav Kulshrestha〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Fuel cells are the promising new non-conventional power source for vehicles as well as portable devices. Direct methanol fuel cell (DMFC) is especially attractive since it uses low cost liquid methanol as a fuel. Proton exchange membrane is one of the most crucial part of DMFC. Herein, we synthesized the sulfonated boron nitride (SBN) based SPEEK composite membranes for the DMFC application. SBN was synthesized by covalent functionalization of hydroxylated BN by using 3-mercaptopropyl trimethoxysilane and sulfonated by subsequent oxidation of mercapto group. Sulfonated poly (ether ether ketone) is used as a polymer matrix for SBN. With well controlled content of SBN into SPEEK matrix exhibit high proton conductivity, IEC and water content along with excellent mechanical strength. Composite membranes show low methanol cross over and high selectivity, which makes them attractive candidate for proton exchange membrane for direct methanol fuel cells.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 10 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy〈/p〉 〈p〉Author(s): Lucas Faccioni Chanchetti, Daniel Rodrigo Leiva, Leandro Innocentini Lopes de Faria, Tomaz Toshimi Ishikawa〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Hydrogen is a promising sustainable energy carrier for the future due to its high energetic content and no emissions, other than water vapor. However, its full deployment still requires technological advances in the renewable and cost-effective production of hydrogen, cost reduction of fuel cells and especially in the storage of hydrogen in a lightweight, compact and safe manner. One way to achieve this is by using materials in which hydrogen bonds chemically, or by adsorption. Different kinds of Hydrogen Storage Materials have been investigated, such as Metal-Organic Frameworks (MOFs), Simple Hydrides (including Magnesium Hydride, MgH〈sub〉2〈/sub〉), AB〈sub〉5〈/sub〉 Alloys, AB〈sub〉2〈/sub〉 Alloys, Carbon Nanotubes, Graphene, Borohydrides, Alanates and Ammonia Borane. Billions have been invested in Storage Materials research, resulting in tens of thousands of papers. Thus, it is challenging to track how much effort has been devoted to each materials class, by which countries, and how the field has evolved over the years. Quantitative Science and Technology Indicators, produced by applying Bibliometrics and Text Mining to scientific papers, can aid in achieving this task. In this work, we evaluated the evolution and distribution of Hydrogen Storage Materials research using this methodology. Papers in the 2000–2015 period were collected from Web of Science and processed in VantagePoint〈sup〉®〈/sup〉 bibliometric software. A thesaurus was elaborated relating keywords and short phrases to specific Hydrogen Storage Materials classes. The number of publications in Hydrogen Storage Materials grew markedly from 2003 to 2010, reducing the pace of growth afterwards until a plateau was reached in 2015. The most researched materials were MOFs, Simple Hydrides and Carbon-based materials. There were three typical trends in materials classes: emerging materials, developed after 2003, such as MOFs and Borohydrides; classical materials with continuous growth during the entire period, such as Simple Hydrides; and stagnant or declining materials, such as Carbon Nanotubes and AB〈sub〉5〈/sub〉 Alloys. The main publishing countries were China, countries from the European Union (EU) and the USA, followed by Japan. There is a division between countries with continued growth in recent years, such as China, and those with stagnant production after 2010, such as the EU, the USA and Japan. The results of this work, compared to a previous study in storage materials patenting by our group, and the recent launch of commercial hydrogen cars and trains and stationary hydrogen production and fuel cell solutions, indicates that although the Hydrogen Energy field as a whole is transitioning from lab and prototype stages to commercial deployment, materials-based hydrogen storage still has base technological challenges to be overcome, and therefore still needs more scientific research before large scale commercialization can be realized. The developed thesaurus is made available for refinement and future works.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy, Volume 187〈/p〉 〈p〉Author(s): Faezeh Esmaeili, Mohsen Gholami, Mohammad Hojjat〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this study, the external surface of a finned tube was coated by 13X zeolite powder, and the CO〈sub〉2〈/sub〉 adsorption equilibrium and dynamics were investigated experimentally. A slurry consisting of dionized water, 13X zeolite powder, and Acrylic latex emulsion (ALE) was used to coat the finned tube. The finned tube was coated by deep coating method. The equilibrium isotherms were measured at the range of 20–90 °C and fitted well by the dual-site Langmuir model. The average difference between the model and the results obtained from the experiments is about 2.5%. The nitrogen adsorption/desorption at 77 K was used for characterization of adsorbents. A 11% reduction was observed in pore volume and surface area. The dynamic test showed that the desorption of adsorbed CO〈sub〉2〈/sub〉 takes place in about 14 s which is an order of magnitude faster than the fastest developed method. A conservative criterion was developed for estimating adsorbent working capacity. This criterion showed that the working capacities of the adsorbent are about 80% of its ideal values.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0360544219317086-fx1.jpg" width="339" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy, Volume 187〈/p〉 〈p〉Author(s): Saber Khanmohammadi, Shoaib Khanmohammadi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉One of the most substantial aspects of the solar still systems that should be significantly considered is their economic and environment aspects. The present study deals with analyzing and identifying the behaviors of a cascade solar still desalination system in the presence of different insulation types and phase change materials. A Matlab code is developed to solve the energy equations for different components of the system simultaneously using ODE-45 solver. A comprehensive thermal, economic and environment analyses performed on the solar still desalination system with different insulation types and phase change materials. With selecting three objective functions namely total annual cost (〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"〉〈mrow〉〈mi〉T〈/mi〉〈mi〉A〈/mi〉〈mi〉C〈/mi〉〈/mrow〉〈/math〉), exergy efficiency (〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si2.svg"〉〈mrow〉〈msub〉〈mrow〉〈mi〉η〈/mi〉〈/mrow〉〈mrow〉〈mi〉e〈/mi〉〈mi〉x〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉), and exergy-based CO〈sub〉2〈/sub〉 mitigation 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si3.svg"〉〈mrow〉〈mrow〉〈mo stretchy="true"〉(〈/mo〉〈mrow〉〈msub〉〈mrow〉〈mi〉φ〈/mi〉〈/mrow〉〈mrow〉〈mi〉C〈/mi〉〈msub〉〈mrow〉〈mi〉O〈/mi〉〈/mrow〉〈mrow〉〈mn〉2〈/mn〉〈/mrow〉〈/msub〉〈mo〉,〈/mo〉〈mi〉e〈/mi〉〈mi〉x〈/mi〉〈mo linebreak="badbreak"〉−〈/mo〉〈mi〉b〈/mi〉〈mi〉a〈/mi〉〈mi〉s〈/mi〉〈mi〉e〈/mi〉〈mi〉d〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈mo stretchy="true"〉)〈/mo〉〈/mrow〉〈/mrow〉〈/math〉, the tri-objective optimization is carried out for two considered cases of solar still desalination units. The thermal analysis represents that among different insulation types phenolic foam with 9.42 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si4.svg"〉〈mrow〉〈mi〉k〈/mi〉〈mi〉g〈/mi〉〈mo linebreak="goodbreak" linebreakstyle="after"〉/〈/mo〉〈msup〉〈mrow〉〈mi〉m〈/mi〉〈/mrow〉〈mrow〉〈mn〉2〈/mn〉〈/mrow〉〈/msup〉〈/mrow〉〈/math〉 per day has the highest value of distilled water production. The total annual cost analysis infers that the system with paraffin as phase change material (PCM) and glass wool as insulation, with 71.67 $, has the lowest TAC. The tri-objective optimization results demonstrate that for both considered cases three objectives are improved considerably compare with non-optimized solar still systems.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy, Volume 183〈/p〉 〈p〉Author(s): Xiao Luo, Dongxu Wu, Congliang Huang, Zhonghao Rao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉To relieve the fresh water shortage, a skeleton double layer structure (SDLS) is developed in this work to give a high evaporation efficiency for solar steam generation. In the SDLS, the bottom layer is dug hollow to prevent heat dissipating from the bottom layer into the bulk water. The method to optimize structure of the SDLS is also given in this work. The increase of height of SDLS has a positive effect on reducing heat losses while negative effect on supplying water, thus a proper height should be selected. After obtaining the proper height, the optimal cross sectional area of the skeleton structure can be approximately calculated based on the mass conservation of water. Applying the optimal SDLS, both of our experiment and simulation methods show that the evaporation rate and the evaporation efficiency under a solar power illumination of 1 sun can be 1.5 kg m〈sup〉−2〈/sup〉 h〈sup〉−1〈/sup〉 and 90% respectively, which is much higher than most emerging structures. The simulation by finite element method further shows that the high evaporation efficiency of the SDLS arrives from the low energy losses. The good match between the simulation and experimental results suggests the reliability of our results. We concluded that the SDLS is a promising system for application in solar steam generation due to its high evaporation efficiency, reusability and also easy to prepare.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy, Volume 183〈/p〉 〈p〉Author(s): Giovanni Barone, Annamaria Buonomano, Francesco Calise, Cesare Forzano, Adolfo Palombo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉This paper presents a novel dynamic simulation model for the analysis of a hybrid turboexpander system coupled with innovative high-vacuum solar thermal collectors. The model is developed in MatLab and it is able to dynamically calculate the energy, exergy, environmental, and economic performances of the investigated system, by taking into account the hourly fluctuation of thermodynamic and economic parameters (e.g. electricity cost, natural gas temperature, and flow rates, etc.). In addition, a computer-based Design of Experiment (DoE) approach was implemented for achieving the optimal design of the proposed system.〈/p〉 〈p〉A suitable case study is presented in order to show the capabilities of the developed simulation tool. Conventional and non-conventional decompression systems located in the weather zone of Messina (South-Italy) are investigated with the aim of assessing the optimal system configuration. By means of the computer-based DoE analysis, the optimal values of several design parameters (such as the number of solar thermal collectors, the volume of the hot water storage tank, and the size of the water loop pump) are calculated. Numerical results show significant primary energy savings (1.36 TWh/year) and avoided carbon dioxide emissions (348 t〈sub〉CO2〈/sub〉/year). From the economic point of view, a feasible simple pay-back period of 4.51 years is achieved. The destroyed exergy of the system components are calculated, obtaining the highest value for the turbo-expander, equal to 12.0 TWh/year.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy, Volume 183〈/p〉 〈p〉Author(s): Kamil Kozłowski, Maciej Pietrzykowski, Wojciech Czekała, Jacek Dach, Alina Kowalczyk-Juśko, Krzysztof Jóźwiakowski, Michał Brzoski〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The aim of this study is to analyse the possibilities of use of waste from dairy production to produce electricity and heat in the process of anaerobic digestion. The analysis covers one of the Polish dairies located in Eastern Poland. The amounts of the substrates produced in analyzed dairy plant will enable the production of approx. 14,785 MWh electricity and 57,815 GJ of heat. This will allow the construction of biogas plant with an electrical power of 1.72 MW. The paper has been stated that the construction of biogas plants for environmental and social reasons is beneficial.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy, Volume 183〈/p〉 〈p〉Author(s): Dongran Song, Yinggang Yang, Songyue Zheng, Weiyi Tang, Jian Yang, Mei Su, Xuebing Yang, Young Hoon Joo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This paper proposes a systematic method that precisely estimates the capacity factor (CF) of the variable-speed wind turbine (WT) by considering the coupled influence of the turbine operation constraints and the air density. To do so, the WT’s operation is defined by introducing the QN-curve (denoting the generator torque versus rotor speed), and the influence of different QN-curves on the power production is analysed while considering the influence of the air density. Then, a practical power-curve model considering the constraint of the QN-curve is derived for the WT. Following that, the formulation and the procedure of CF estimation are presented. Lastly, the presented CF estimation approach is applied into an industrial WT while considering the wind sites with four different altitudes. Finally, the application results show the capabilities of the proposed approach in evaluating the CF under the coupled influence of the QN-curve constraint and the air density. Meanwhile, comparing the proposed approach to four empirical approaches demonstrates that the CF estimation based on empirical models has considerable deviations to the results of the presented model under different site altitudes. Furthermore, among the four empirical models, the CF estimations from the quadratic and the linear models present the least deviations to those by the proposed model at the sites with low altitude and high altitude, respectively.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy, Volume 183〈/p〉 〈p〉Author(s): Boqiang Lin, Hermas Abudu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Particularly for developing regions like Sub Saharan Africa, energy intensity is a critical policy issue and usually affected by four challenges: substitution between energy and other factors, technological change, changes in energy composition, and changes of economic growth. This paper examines energy intensity, output elasticity, energy-capital-labor substitution possibility, and factors contribution rates. The study applies a Translog production approach with data spanning 1990–2014 and further, applies ridge regression technique as a robust rectification to achieve unbiasedness in the findings. There is expected evidence of inverse relationship: higher energy intensity in lower per capita economy, evidenced by upward energy tariffs with lower energy elasticity. Factors are inelastic and have average elasticity substitution possibility for capital-energy with their inferential rebound effects’ challenges. However, other combinations indicate complementarity at the current development stage. We further, observe that if higher energy intensity not managed, would translate into higher CO〈sub〉2〈/sub〉 intensity, because 99% of total energy is sourced from hydrocarbons of 51% and 48% of biomass. Based on the findings, policymakers and implementors are encouraged to integrate and optimize the whole energy system towards improving energy efficiency through increasing renewable energy composition from the current 1% to at least 10% whiles increasing quality-energy from nonrenewable.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy, Volume 183〈/p〉 〈p〉Author(s): Lanchuan Zhang, Jun Li, Yifei Wu, Mingyun Lv〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Solar energy is an essential energy source collected by photovoltaic (PV) cells for long-endurance stratospheric airships. Attitude control is crucial for the energy production of the PV array attached to the airship hull. This study was conducted to analyze the energy balance of stratospheric airships with attitude planning. A solar radiation and PV array model is proposed, then a steerable attitude strategy is established considering the roll, pitch, and yaw control of the PV array. The energy balance of the model is analyzed under an attitude planning scheme based on an actual airship design. The daily net energy of the airship is calculated according to monthly wind data of various latitudes. The influence on the net energy considering the conversion efficiency of PV cells and specific density of the energy stored system (ESS) is also analyzed. The results shows that attitude planning has a significant effect on both the energy production and wind resistance of the airship. The energy balance of the airship is markedly improved when PV conversion efficiency is high and ESS energy capacity is large. The results presented here may prove valuable for future stratospheric airship applications.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy, Volume 183〈/p〉 〈p〉Author(s): Zhuochun Wu, Liye Xiao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Accurate wind speed forecasting ensures the controllability for the wind power system. In this paper, a structure with density-weighted active learning (DWAL)-based model selection strategy from the perspective of meteorological factors is proposed to improve the accuracy and stability for wind speed deterministic and probabilistic forecasting. To improve training efficiency and accelerate the sample selection process, DWAL is employed. The multi-objective flower pollination algorithm is used to combine best models selected from model space with optimal weights for higher accuracy and stability. Except deterministic forecasts, as large-scale wind power generation integrated into power grid, the wind direction should also be forecasted and the estimation of the wind speed and direction uncertainty is vital, offering various aspects of forecasts for risk management. Thus, both deterministic and probabilistic forecasting for the wind speed vector are included in this paper. Eight datasets from Ontario Province, Canada, are utilized to evaluate forecasting performance of the model selection and the proposed structure. Results demonstrated: (a) the proposed structure is suitable for wind speed vector forecasting; (b) the proposed structure obtains more precise and stable forecasting performance; (c) the proposed structure improves the accuracy of deterministic forecasting and provides probabilistic information for wind speed vector forecasting.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy, Volume 183〈/p〉 〈p〉Author(s): Matt Lewis, James McNaughton, Concha Márquez-Dominguez, Grazia Todeschini, Michael Togneri, Ian Masters, Matthew Allmark, Tim Stallard, Simon Neill, Alice Goward-Brown, Peter Robins〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Temporal variability in renewable energy presents a major challenge for electrical grid systems. Tides are considered predictable due to their regular periodicity; however, the persistence and quality of tidal-stream generated electricity is unknown. This paper is the first study that attempts to address this knowledge gap through direct measurements of rotor-shaft power and shore-side voltage from a 1 MW, rated at grid-connection, tidal turbine (Orkney Islands, UK). Tidal asymmetry in turbulence parameters, flow speed and power variability were observed. Variability in the power at 0.5 Hz, associated with the 10-min running mean, was low (standard deviation 10–12% of rated power), with lower variability associated with higher flow speed and reduced turbulence intensity. Variability of shore-side measured voltage was well within acceptable levels (∼0.3% at 0.5 Hz). Variability in turbine power had 〈1% difference in energy yield calculation, even with a skewed power variability distribution. Finally, using a “t-location” distribution of observed fine-scale power variability, in combination with an idealised power curve, a synthetic power variability model reliably downscaled 30 min tidal velocity simulations to power at 0.5 Hz (R〈sup〉2〈/sup〉 = 85% and ∼14% error). Therefore, the predictability and quality of tidal-stream energy was high and may be undervalued in a future, high-penetration renewable energy, electricity grid.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy, Volume 187〈/p〉 〈p〉Author(s): Jian Chen, Xiong Pan, Canxing Wang, Guojun Hu, Hongtao Xu, Pengwei Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The airfoil research is one of the most essential issue which has great influence on the vertical axis wind turbine (VAWT) performance. Thus, a comprehensive research was conducted in this study with the objective of evaluating the effect of the twelve airfoils' controlling parameters on a Darrieus rotor's performance. The airfoil parameterization method, orthogonal algorithm and computational fluid dynamic (CFD) prediction were intergtated to fulfill this objective. A modification was conducted for the airfoil parameterization method to avoid trailing edge crossing and make controlling parameter's geometrical meaning more explicitly. The analysis results sorted the effect of design parameters by impact weight or contribution ratio. A remarkable finding was that the design parameters on the lower surface have greater influence than those on the upper surface. Orthogonal analysis gained a best airfoil whose power coefficient (C〈sub〉P〈/sub〉) is 13.26% larger than that of NACA 0015. Flow field analysis found that a tiny positive vortex was enlarged intensively with the increasing of the azimuth angle, which degrades the rotor's performance.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy, Volume 187〈/p〉 〈p〉Author(s): Thi Anh Tuyet Nguyen, Shuo-Yan Chou〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉One of the most critical impediments of developing offshore wind systems is the high maintenance cost that reduces the cost-effectiveness of projects. To increase the cost-effectiveness of offshore wind energy, an effective solution is to reduce the overall maintenance cost by improving the efficiency of maintenance activities. Although maintenance optimization is crucial for improving cost-effectiveness, no model in the literature has analyzed the effects of government subsidies, the time value of money, the cost of lost power generation, and location on the optimal maintenance schedule. This study proposes an approach for thoroughly investigating the effects of various factors such as government subsidies, the time value of money, lost power generation, and location on maintenance cost. A dynamic approach was developed to determine the optimal maintenance schedule with the objective of minimizing the present maintenance cost on the time horizon. The results demonstrated that the optimal maintenance schedule varied according to changes in government subsidies under the influence of the time value of money. Moreover, the effect on the maintenance schedule became greater when government subsidies increased.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy, Volume 187〈/p〉 〈p〉Author(s): Mohamed Adel Sayed, Mostafa R. Abukhadra, Mohamed Abdel Salam, Sobhy M. Yakout, Ahmed A. Abdeltawab, Ibrahim M. Aziz〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Novel heulandite/polyanailine@Ni〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 composite (Hu/PAN@NiO) was fabricated as an advanced product of enhanced photocatalytic properties and low band gap energy for efficient hydrogen generation. The composite was characterized and identified through different techniques including XRD, HRTEM, SEM, and FTIR in addition to the investigation of its textural and optical properties. The fabricated composite is of a significantly high surface area (531 m〈sup〉2〈/sup〉/g) and low band gap that reaches about 1.46 eV which strongly qualifies the product electrode in photo-electrochemical hydrogen generation processes. The synthetic composite exhibits effective photocatalytic performance in the photoelectrochemical splitting of water under a visible light source. The detected photocurrent density reached 4.7204 mAcm〈sup〉−2〈/sup〉 and the hydrogen production rate was estimated to be 4.1 μmol/h〈sup〉−1〈/sup〉cm〈sup〉−2〈/sup〉 after about 50 min at an applied voltage of +1V. The obtained results reflected the potentiality of such hybrid material as an effective catalyst in the photo-electrochemical splitting of water for hydrogen production.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy, Volume 187〈/p〉 〈p〉Author(s): Mathieu Legrand, Luis Miguel Rodríguez-Antón, Carmen Martinez-Arevalo, Fernando Gutiérrez-Martín〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The European energy transition implies a relevant increase of renewable energies in the electric power generation mix. Integrating additional renewables is becoming more challenging due to their variability. Spain's peninsular situation aggravates this problem because it is an electric island. Within this framework, Liquid Air Energy Storage (LAES) is a promising technology for balancing the power grid. This work proposes a transient thermodynamic modelling of a 100 MW LAES plant. The cycle incorporates a packed-bed cold-storage system to enhance the charge/discharge efficiency. The appearance of a thermocline in the cold-storage unit is relevant regarding the round-trip efficiency. An economic study based on the simulation results is performed considering different scenarios of renewables grid penetration (photovoltaic and wind power). Depending on the installed LAES capacity, the levelized cost of delivered energy is evaluated. The results suggest that it is more interesting to store photovoltaic energy in the daytime peak hours and release energy during the night-time valleys to maximize the use of storage plants. This allows the levelized cost of energy and storage to be reduced to values as low as 150 and 50 €/MWh respectively. These prices are competitive with compressed air energy storage and even with pumped-hydro storage.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S036054421931655X-egi102Q5CTF2PS.jpg" width="367" alt="Image 10252" title="Image 10252"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy, Volume 187〈/p〉 〈p〉Author(s): Salim Issaadi, Wassila Issaadi, Abdelkrim Khireddine〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉To increase the power output of a PV module or a field of PV modules, an electronic controller is incorporated between the PV generator and the load, whose role and main objective is the continuous monitoring of the maximum power point of the PV generator commonly known as MPPT (Maximum Power Point Tracking) and this in general per action on a DC-DC conversion device.〈/p〉 〈p〉The regulation and control techniques provide the impedance matching function, transferring to the load the maximum electrical power output from the PV generator in any the temperature and sunshine conditions.〈/p〉 〈p〉The development of a revolutionary method based on neural algorithms for the prediction of an instantaneous command is the main objective in our work.〈/p〉 〈p〉Indeed, the paper presents a new control strategy for the photovoltaic PV, it is a command based on Neuronal Network technique. It is the first time that this technique has been introduced, and proposed by the authors in synthesizing control laws for the converters of electronic power.〈/p〉 〈p〉The new technical algorithm based on Neural Networks, is designed to be more robust in performance with respect to tracking speed and precision.〈/p〉 〈p〉Moreover, this new successful technical research, provides a robust neural structure compared to the noisy empirical data used for the prediction of the command. Consequently a smooth control signal without oscillation, targeting exactly the expected optimal control with an independent control of the sampling frequency of the system.〈/p〉 〈p〉This study, which is followed by a simulation, has enabled us to consolidate the idea that the new Neural Network controller when compared to their classical counterparts, and obtains the best performances concerning the speed of tracking and precision.〈/p〉 〈p〉The robustness of the networks of neurons opposite the noise of measurements, like, the smoothness of the power signal of PV system generated during the application of the neuronal order, will qualify this command as a practical alternative to the disadvantages recorded on the levels of the classical methods.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 23 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy〈/p〉 〈p〉Author(s): R.A.R. Ferreira, C.N. Ávila-Neto, F.B. Noronha, C.E. Hori〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Liquefied petroleum gas (LPG) is a mixture of hydrocarbons that has a broad distribution network in several countries. In this context, the objective of this study was to evaluate the steam reforming of LPG using catalysts derived from hydrotalcites. The precursors were characterized by X-ray fluorescence analysis, BET surface area, temperature programmed reduction, thermogravimetric analysis, 〈em〉in situ〈/em〉 X-ray diffraction spectroscopy and X-ray absorption spectroscopy. Catalysts were synthesized with 47.5% Ni content without increasing the particle diameter. All catalysts showed the formation of the same gas phase products: H〈sub〉2〈/sub〉, CO, CH〈sub〉4〈/sub〉 and CO〈sub〉2〈/sub〉. Ni〈sub〉1.64〈/sub〉Mg〈sub〉1.36〈/sub〉Al catalyst showed the highest conversion (about 70%) and lower deactivation by coke deposition after 24 h reaction. The use of higher reaction temperatures (1073 and 1173 K), for steam reforming process, resulted in higher conversions of LPG, increased formation of H〈sub〉2〈/sub〉 and lowered the formation of carbon deposits.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 3 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy, Volume 44, Issue 42〈/p〉 〈p〉Author(s): Rami S. El-Emam, Ibrahim Dincer, Calin Zamfirescu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Nuclear energy is considered a key alternative to overcome the environmental issues caused by fossil fuels. It offers opportunities with an improved operating efficiency and safety for producing power, synthetic fuels, delivering process heat and for multigeneration applications. The high-temperature nuclear reactors, although possess great potential for integration with thermochemical water-splitting cycles for hydrogen production, are not yet commercially established. Current nuclear reactor designs providing heat at relatively low temperature can be utilized to produce hydrogen using thermochemical cycles if the temperature of their thermal heat is increased. In this paper, a hybrid chemical-mechanical heat pump system is proposed for upgrading the heat of the Enhanced CANDU (EC6) reactor design to the quality required for the copper-chlorine (Cu–Cl) hybrid thermochemical water splitting cycle operating at 550–600 °C. A modification to the heat pump is proposed to bring the heat to temperature higher than 650 °C with operating coefficient of performance estimated as 0.65.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 3 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy, Volume 44, Issue 42〈/p〉 〈p〉Author(s): Yong Zhang, Guangwu Wen, Shan Fan, Wenhui Ma, Shuhua Li, Tao Wu, Zhaochuan Yu, Baoru Zhao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉At present, amino acids are often used as the source of heteroatom functional groups for the preparation of doped graphene materials. However, a large amount of amino acids will be used as reaction precursors in the preparation process, which will lead to increased cost, reduced efficiency and waste of resources. Herein, a very small amount of neutral 〈span〉l〈/span〉-alanine is employed to synthesize 3D carboxyl and hydroxyl co-enriched graphene hydrogels (CHGHs) by a one-pot hydrothermal method. The CHGHs contain copious carboxyl and hydroxyl groups, and a small amount of nitrogen-containing functional groups. In addition, the CHGHs also present large specific surface areas and 3D porous structures. Therefore, the CHGH-20 binder-free electrode displays a high specific capacitance of 262.8 F g〈sup〉−1〈/sup〉 at 0.3 A g〈sup〉−1〈/sup〉, and this value still maintains 84.3% (221.6 F g〈sup〉−1〈/sup〉) at 10 A g〈sup〉−1〈/sup〉 in a two-electrode system in 6 M KOH. Furthermore, the CHGH-20 electrode also displays outstanding cycle stability with 103.6% of its initial capacitance after 10,000 cycles at 10 Ag〈sup〉−1〈/sup〉. Therefore, the CHGHs samples prepared by a very small amount of neutral 〈span〉l〈/span〉-alanine have great significance for the practical application of supercapacitors.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0360319919325935-fx1.jpg" width="281" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 3 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy, Volume 44, Issue 42〈/p〉 〈p〉Author(s): Shitanshu Sapre, Kapil Pareek, Rupesh Rohan, Pawan Kumar Singh〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Hydrogen as compressed gas is a promising option for zero-emission fuel cell vehicle. The fast and efficient refueling of high pressure hydrogen can provide a convenient platform for fuel cell vehicles to compete with conventional gasoline vehicles. This paper reports the finding of adiabatic simulation of the refueling process for Type IV tank at nominal working pressure of 70 MPa with considering the station refueling conditions. The overall heat transfer involved in refueling process was investigated by heat capacity model based on MC method defined by SAE J2601. The simulation results are validated against experimental data of European Commission's Gas Tank Testing Facility at Joint Research Centre (GasTef JRC), Netherlands. The results confirmed that end temperature and state of charge significantly depends on refueling parameters mainly supply hydrogen temperature and filling rate.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 3 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy, Volume 44, Issue 42〈/p〉 〈p〉Author(s): Ekaterina A. Kozlova, Evgenii N. Gribov, Anna Yu. Kurenkova, Svetlana V. Cherepanova, Evgeny Yu. Gerasimov, Denis V. Kozlov〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Novel composite photocatalysts consisting of a cadmium and zinc sulfide solid solution (Cd〈sub〉0.6〈/sub〉Zn〈sub〉0.4〈/sub〉S) and zinc sulfide (ZnS) nanoparticles were successfully prepared by a simple hydrothermal treatment of suspended Cd〈sub〉0.3〈/sub〉Zn〈sub〉0.7〈/sub〉S at 120 °C. The as-obtained materials were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and UV-VIS diffuse reflection spectroscopy. The obtained photocatalysts were tested in the photocatalytic evolution of hydrogen from a Na〈sub〉2〈/sub〉S/Na〈sub〉2〈/sub〉SO〈sub〉3〈/sub〉 aqueous solution under visible light irradiation (λ = 450 nm). It is shown that the hydrothermal treatment of Cd〈sub〉0.3〈/sub〉Zn〈sub〉0.7〈/sub〉S at 120 °C increases the activity by a factor of 7.5 due to the phase transformations of the solid solution with the formation of the multiphase Cd〈sub〉0.6〈/sub〉Zn〈sub〉0.4〈/sub〉S/ZnS sample. The deposition of gold on the surface of Cd〈sub〉0.6〈/sub〉Zn〈sub〉0.4〈/sub〉S/ZnS leads to a further increase in activity: the achieved photocatalytic activity and quantum efficiency (450 nm) for 1%Au/Cd〈sub〉0.6〈/sub〉Zn〈sub〉0.4〈/sub〉S/ZnS are 17.4 mmol g〈sup〉−1〈/sup〉 h〈sup〉−1〈/sup〉 and 42.6%, respectively. This excellent performance is found to be attributable to the transformation of Cd〈sub〉1-x〈/sub〉Zn〈sub〉x〈/sub〉S from the cubic to the hexagonal phase during the hydrothermal treatment. Additionally, photoelectrodes based on Cd〈sub〉0.6〈/sub〉Zn〈sub〉0.4〈/sub〉S/ZnS and FTO were synthesized and tested in a two-electrode cell. A high value of the photocurrent equal to 0.5 mA/cm〈sup〉2〈/sup〉 is achieved for the Cd〈sub〉0.6〈/sub〉Zn〈sub〉0.4〈/sub〉S/ZnS/FTO electrode. An investigation by means of impedance spectroscopy reveals the longer lifetime of photogenerated charge carriers in the Cd〈sub〉0.6〈/sub〉Zn〈sub〉0.4〈/sub〉S/ZnS/FTO photoelectrode if to compare with Cd〈sub〉0.3〈/sub〉Zn〈sub〉0.7〈/sub〉S/FTO system.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0360319919326369-fx1.jpg" width="215" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy, Volume 183〈/p〉 〈p〉Author(s): Sofiane Kichou, Nikolaos Skandalos, Petr Wolf〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Energy management is very important for the effective operation of a hybrid system composed of various energy sources. The present work aims to develop an effective control strategy in order to reduce the grid-maximal contracted power of a hybrid building containing PV systems, combined heat and power (CHP) unit and battery energy storage system (BESS). The proposed solutions (new control strategy and increased PV system size) were carried out based on the analysis of monitored data collected from May 2016 to April 2017 representing the real behaviour of the hybrid system.〈/p〉 〈p〉The obtained results demonstrated the effectiveness of the developed control strategy in decreasing the grid-maximal contracted power from 140 kW to 120 kW and increasing the self-sufficiency of the building. Furthermore, by combining the proposed control strategy and the proposed PV system, the self-sufficiency can be even more increased and the grid-maximal power can be reduced by 30% leading to an annual savings of almost 4000 €/year.〈/p〉 〈p〉Finally, the financial assessment revealed that the payback period of the proposed solution is less than 10 years confirming the profitability of the investment.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy, Volume 183〈/p〉 〈p〉Author(s): Qiang Wang, Kun Luo, Chunlei Wu, Jianren Fan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The environment-friendly development of wind power is complicated as the atmospheric impacts of wind farms are difficult to measure. Wind power has made contributions to emission reduction, but it is undeniable that the substantial wind farms (SWFs) have had a non-negligible impact on the local ABL. This paper aims to provide a reliable methodological scheme and practical data for human beings to objectively understand the development of wind power. Based on the data from one of the Chinese gigawatt-scale wind power bases in Zhangbei County of Hebei Province, the mesoscale simulations were conducted to explore the impacts of substantial wind farms on the local and regional atmosphere. The results show that: (i) the impact of substantial wind farms on the local area is significant and sustained, while this impact on the regional area is slight and occasional; (ii) it can bring about the seasonal and diurnal differences in the local ABL property; (iii) it can not only induce the horizontal turbulence directly caused by wind turbine wake flow, but also produce the vertical mixing in the near-surface ABL. A systematic analysis of wind power potential and its atmospheric impact is urgent to ensure sustainable development of wind power.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy, Volume 183〈/p〉 〈p〉Author(s): Hüseyin. Karaca, Cemil Koyunoğlu, Ali Özdemir, Kenan Ergun〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this work, the liquefaction of coal and biomass with direct liquefaction strategy was explored. The point of liquefaction is both to utilize a greater amount of the current coal and biomass assets all the more productively and to create an alternative liquid fuel to oil. Along these lines, the procedure parameters must be resolved to expand the liquefaction efficiency. In addition, it is proposed to do the liquefaction efficiency, particularly in the reactant conditions, to expand the measure of oil. Process parameters were controlled by utilizing Factorial Experimental Design technique in the liquefaction procedures. The solid/liquid ratio was changed as 1/2-1/4, the catalyst concentration was 2–6%, the temperature was 375–400 °C and the duration was 30–90 min. Starting nitrogen pressure was set at 30 bar, stirring speed was 400 rpm, coal/biomass proportion was settled at 1/1. Tetralin as a solvent and MoO〈sub〉3〈/sub〉 as catalyst were utilized. Toward the finish of the liquefaction procedure, the total conversions were computed in view of the acquired non-reactive solid (char). As indicated by the outcomes obtained, the most total conversion (81.9%) was acquired at a solid/liquid proportion of 1/2, a catalyst concentration of 2%, a reaction time of 90 min and a reaction temperature of 400 °C. In light of total conversions and elective liquid fuel (oil) in the given conditions, the solid/liquid ratio should be taken as 1/2, the catalyst concentration is 2%, the reaction time is 30–90 min and the reaction temperature is 400 °C. The lowest reaction time found, in this study, is the innovative solution for reducing co-liquefaction cost preferred.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 22 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy〈/p〉 〈p〉Author(s): M. Garara, H. Benzidi, M. Lakhal, M. Louilidi, H. Ez-Zahraouy, A. El Kenz, M. Hamedoun, A. Benyoussef, A. Kara, O. Mounkachi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Owing to the existence of periodic channels in phosphorene, this 2D material can be a good candidate for room temperature reversible hydrogen storage. The density functional theory calculations (DFT), including van der Waals interactions (vdW-DF2) coupled with the cooper exchange functional (C09), has been applied to study the potential of phosphorene as a new 2D material for hydrogen storage. Our results show that the adsorption energy (−292 to −277 meV) of H〈sub〉2〈/sub〉 on phosphorene is appropriate for storage. The analysis of diffusion pathways between different physisorbed states on phosphorene shows that a single hydrogen molecule diffuses very easily along the open channel (less than 1 meV along the zigzag direction), as compared to 14 meV for diffusion across the channels (along the armchair direction). The potential energy surfaces for the dissociative chemisorption of H〈sub〉2〈/sub〉 was computed on highly symmetric sites of phosphorene and the highest activation barrier was found to be 2.77 eV. The very large dissociation energy coupled with a strong physisorption of H〈sub〉2〈/sub〉 on phosphorene and facile diffusion, makes this 2D material a promising candidate for H〈sub〉2〈/sub〉 storage at room temperature.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy, Volume 187〈/p〉 〈p〉Author(s): Dhivya Sampath Kumar, Anurag Sharma, Dipti Srinivasan, Thomas Reindl〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉With the shift in renewable portfolio standards, conventional fossil-fuel based generators are expected to be partially or fully replaced with renewable energy sources such as photovoltaics (PVs). However, replacing the conventional synchronous generators with PV generators may raise new stability concerns such as lack of inertia, insufficient reactive power and voltage fluctuations, which can jeopardize the reliability of the entire network. In this paper, various impacts of integrating utility-scale PVs and rooftop PVs and replacing the existing conventional generators on the stability of a power network are investigated. Detailed steady state, transient and small signal analyses are conducted on a large test system, namely Texas 2000-bus system for different PV penetration levels. System transients such as line faults, double-line faults, loss of generator, loss of PVs and cloud cover scenarios are simulated to study their impacts on the test system with different PV penetration levels. It is demonstrated from the impact analysis that the benefits of PVs are highly dependent on a spectrum of factors such as node criticality, type, location and penetration of PVs, and type of transients. Furthermore, the influence of battery energy storage system that are generally associated with PVs on the system stability is also discussed.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy, Volume 187〈/p〉 〈p〉Author(s): Zhengzhi Deng, Chen Wang, Peng Wang, Pablo Higuera, Ruoqian Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉As an example of multipurpose utilization of marine structures, the hydrodynamic performance of an offshore-stationary Oscillating Water Column (OWC) device with an immersed horizontal bottom plate was investigated through both experimental tests and numerical simulations. Based on the open source package OpenFOAM and toolbox waves2Foam, the numerical results were validated by comparing them with experimental data. The effects of the opening ratio (〈em〉a〈/em〉), plate length (〈em〉D〈/em〉), relative opening (〈em〉ε〈/em〉), and water depth on the energy absorption efficiency, transmission coefficient, and energy dissipation coefficient were examined over a wide range of wave conditions. The results show that a relatively long bottom plate and small opening ratio is beneficial for both the energy extraction and wave-damping ability, especially for long waves. Increasing the relative vertical opening considerably improves the performance of multipurpose OWC devices. Moreover, the optimal structure configuration is found for parameters 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"〉〈mrow〉〈mi〉a〈/mi〉〈mo linebreak="goodbreak" linebreakstyle="after"〉=〈/mo〉〈mn〉0.65〈/mn〉〈mtext〉%〈/mtext〉〈/mrow〉〈/math〉, 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si2.svg"〉〈mrow〉〈mi〉D〈/mi〉〈mo linebreak="goodbreak" linebreakstyle="after"〉=〈/mo〉〈mn〉2〈/mn〉〈mi〉B〈/mi〉〈/mrow〉〈/math〉 (〈em〉B〈/em〉 is the breadth of chamber), and 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si3.svg"〉〈mrow〉〈mi〉ε〈/mi〉〈mo linebreak="goodbreak" linebreakstyle="after"〉=〈/mo〉〈mn〉1〈/mn〉〈mo linebreak="goodbreak" linebreakstyle="after"〉/〈/mo〉〈mn〉2〈/mn〉〈/mrow〉〈/math〉.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy, Volume 187〈/p〉 〈p〉Author(s): Hongping Quan, Pengfei Li, Wenmeng Duan, Liao Chen, Langman Xing〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉With the increasing of oil demand and the decreasing of conventional crude oil production, unconventional crude oil is gaining interest. A flow improver (FI) was synthesized and designed a series of methods for investigating the effect of the flow improver on the asphaltene and resin of two unconventional crude oil samples. Changes in the morphology of the solid samples, as determined by scanning electron microscopy. 〈em〉n〈/em〉-Heptane and alcohol were selected as poor solvents for asphaltene and resin, respectively, to prepare solution samples of different concentrations. The precipitation tendency was judged according to the color change of the solution. Fluorescence microscopy was used to observe the changes in the aggregation morphology of the solution samples before and after FI addition. Solid samples and solution samples were tested by XRD and UV spectrophotometry, respectively. The results consistently showed that the effect of FI on resin was better than that on asphaltene. The effect of asphaltene and resin on the viscosity of crude oil was investigated through the series of studies.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 10 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Hydrogen Energy〈/p〉 〈p〉Author(s): M.S. Yahya, N.A. Ali, N.A. Sazelee, N.S. Mustafa, F.A. Halim Yap, M. Ismail〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Notable effects of Li〈sub〉3〈/sub〉AlH〈sub〉6〈/sub〉 on the hydrogen storage properties of the NaBH〈sub〉4〈/sub〉 are studied intensively. Li〈sub〉3〈/sub〉AlH〈sub〉6〈/sub〉 is synthesized by milling 2LiH-LiAlH〈sub〉4〈/sub〉 mixture for 12 h. The best molar ratio of the NaBH〈sub〉4〈/sub〉- Li〈sub〉3〈/sub〉AlH〈sub〉6〈/sub〉 destabilized system is 1:1 which has decomposed at two stages; Li〈sub〉3〈/sub〉AlH〈sub〉6〈/sub〉 decomposition stage at 170 °C and NaBH〈sub〉4〈/sub〉decomposition stage at 400 °C. As no significant effect on the decomposition temperature between 1 h and 24 h of milling time can be observed, the 1-hour milling preparation method is selected for the characterization. Isothermal absorption has shown that the system is able to absorb 4.2 wt% and 6.1 wt% of hydrogen in 60 min at 330 °C and 420 °C under 30 atm of hydrogen pressure. In contrast, only about 3.4 wt% and 3.7 wt% of hydrogen can be absorbed by the milled NaBH〈sub〉4〈/sub〉 under a similar condition. Meanwhile, the system is able to desorb 2.0 wt% and 4.1 wt% of hydrogen in 60 min at 330 °C and 420 °C in isothermal desorption while only 0.3 wt% and 2.1 wt% can be released by the milled NaBH〈sub〉4〈/sub〉 under the similar condition. The decomposition activation energy and enthalpy of the NaBH〈sub〉4〈/sub〉 stage are calculated to be 162.1 kJ/mol and 68.1 kJ/mol H〈sub〉2〈/sub〉. Based on the X-ray diffraction analysis, Na, Al and AlB〈sub〉2〈/sub〉 are formed during the dehydrogenation process. The formation of Al and AlB2 are the keys to the improvement of hydrogenation properties. It is concluded that Li〈sub〉3〈/sub〉AlH〈sub〉6〈/sub〉 is a good destabilizing agent for the NaBH〈sub〉4〈/sub〉 system.〈/p〉〈/div〉 〈/div〉