Semi-methanolysis reaction of potassium borohydride with phosphoric acid for effective hydrogen production Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-22 Asım Balbay, Cafer Saka
The methanol and water solvents were used for the production of hydrogen from potassium borohydride. In addition, phosphoric acid was selected as the green catalyst so that this semi-methanolysis reaction would be more effective for the first time. The semi-methanolysis of potassium borohydride is investigated depend on potassium borohydride, phosphoric acid concentrations and temperatures. The maximum normalized hydrogen production rate obtained from this semi-methanolysis reaction with 1 M phosphoric acid as a catalyst was 5779 ml min −1 g−1. In addition, this semi-methanolysis reaction was completed in 5 s. Kinetic studies have been carried out with the power law kinetic model. The activation energy obtained for this semi-methanolysis reaction is 1.45 kJ mol−1.
Monte-Carlo-analysis of minimum load cycle requirements for composite cylinders for hydrogen Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-22 G.W. Mair, B. Becker, B. Wang, S. Gesell
Hydrogen is an attractive energy carrier that requires high effort for safe storage. For ensuring safety, storage cylinders must undergo a challenging approval process. Relevant standards and regulations for composite cylinders used for the transport of hydrogen and for its onboard storage are currently based on deterministic (e.g. ISO 11119-3) or to some respect semi-probabilistic criteria (UN GTR No. 13; with respect to burst strength).This paper provides a systematic analysis of the load cycle properties resulting from these regulations and standards. Their characteristics are compared with the probabilistic approach of the Federal Institute for Materials Research and Testing BAM. The most important aspect of comparing different concepts is the rate for accepting designs with potentially unsafe or critical safety properties. This acceptance rate is analysed by operating Monte-Carlo simulations over the available range of production properties.
Long-life Ni-MH batteries with high-power delivery at lower temperatures: Coordination of low-temperature and high-power delivery with cycling life of low-Al AB5-type hydrogen storage alloys Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-22 Wanhai Zhou, Ding Zhu, Kun Liu, Jinchi Li, Chaoling Wu, Yungui Chen
Trends in design of distributed energy systems using hydrogen as energy vector: A systematic literature review Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-22 Juan D. Fonseca, Mauricio Camargo, Jean-Marc Commenge, Laurent Falk, Iván D. Gil
Currently, a significant transformation for energy systems has emerged as a result of the trend to develop an energy framework without fossil fuel reliance, the concerns about climate change and air quality, and the need to provide electricity to around of 17% of world population who lacks the service. Accordingly, the deployment of power plants located close to end-users and including multiple energy sources and carriers, along with the growing share of renewable energies, have suggested changes in the energy sector. Despite their potential capabilities, the design of distributed energy systems (DES) is a complex problem due to the simultaneous goals and constraints that need to be considered, as well as to the high context dependence of this kind of projects. For these reasons, in this work a systematic literature review of DES including hydrogen as energy vector, was made analyzing 106 research papers published between the years 2000–2018, and extracted from Scopus® and Web of Science databases. The aim was to identify how hydrogen is employed (technologies, uses) and the criteria that are evaluated (economic, technical, social and environmental) when these systems are designed, planned and/or operated. The results constitute a baseline information covering the type of technologies, equipment sizes and hydrogen applications, that could be valuable for the preliminary stages of research or project planning of DES involving hydrogen. Furthermore, other factors have also been identified, such as the focus on techno-economic issues, and the lack of considering socio/political aspects and the uncertainty about input data like weather conditions, energy prices and demands. Additionally, a more integrated approach is needed including all the hydrogen supply chain stages and project stakeholders, to tackle issues like safety of the energy systems that could produce consumer rejections.
Optimization of interconnect flow channels width in a planar solid oxide fuel cell Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-19 Xiaolian Li, Wangying Shi, Minfang Han
Finite element analysis is an effective method to investigate the uniformity of species distribution in solid oxide fuel cells. This paper presents a 3-D model with coupled mass transport, electron transfer and electrochemical reaction. Based on a working anode-supported SOFC with gas channels and porous electrodes, the model is validated by measured IV curves. The simulated results deviate no more than 3% from the measured data and indicate significant dependency of current density distribution on the gas composition distribution. Meanwhile, the simulated results also indicate that the ridges of the interconnect have negative effects on electrochemical reaction due to the limitation of mass transport. In further study, cases of various channel widths are calculated and analyzed, finding that the optimal width ratios for electrochemical in cathode and anode are 0.5.
Comparison of co–gasification efficiencies of coal, lignocellulosic biomass and biomass hydrolysate for high yield hydrogen production Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-19 Açelya Seçer, Nilgün Küçet, Ender Fakı, Arif Hasanoğlu
The diversity in the chemical composition of lignocellulosic feedstocks can affect the conversion technologies employed for hydrogen production. Gasification and co–gasification activities of lignocellulosic biomass, biomass hydrolysate, and coal were evaluated for hydrogen rich gas production. The hydrolysates of biomass materials showed the best performance for gasification. The results indicated that biomass hydrolysates obtained from lignocellulosic biomass were more sensitive to degradation and therefore, produced more hydrogen and gaseous products than that of lignocellulosic biomass. The effects of feed (kenaf and sorghum hydrolysate), flow rate (0.3–2.0 mL/min) and temperature (700–900 °C) on hydrogen production and gasification yields were investigated. It was observed that 0.5 mL/min the optimum feed flow rate for the maximum total gas and hydrogen production. Synergism effects were observed for co–gasification of coal/biomass and coal/biomass hydrolysate. In all co–gasification processes, the main component of the gas mixture was hydrogen (≥70%).
Hydrogen production by direct injection of ethanol microdroplets into nitrogen microwave plasma flame Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-19 Dariusz Czylkowski, Bartosz Hrycak, Mariusz Jasiński, Mirosław Dors, Jerzy Mizeraczyk
Challenges arising from the use of TiO2/rGO/Pt photocatalysts to produce hydrogen from crude glycerol compared to synthetic glycerol Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-19 Paula Ribao, M. Alexandra Esteves, Vitor R. Fernandes, Maria J. Rivero, Carmen M. Rangel, Inmaculada Ortiz
Binderless, bendable graphene/FexSn1-xO2 anode for lithium-ion batteries without the necessity of a current collector Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-19 Xueqian Zhang, Xiaoxiao Huang, Dongdong Liu, Tuan K.A. Hoang, Xin Geng, Pu Chen, Xiaodong Zhang, Guangwu Wen
SnO2 is an appealing anode material for lithium ion batteries. Advantages of SnO2 includes relatively low charge-discharge plateau and highly abundance in nature. However, the volume change (300%) is significant and critically impeding its cycle life. In this manuscript, we address these problems by exploiting an in-situ redox process to prepare graphene encapsulated SnO2 nanoparticles using soluble Sn2+ as the Sn precursor, which is oxidized to SnO2 by using graphene oxide. This method affords graphene @ SnO2 via oxygen bridging through of SnO2 nanoparticles. Furthermore, this method incorporates Fe atom into the SnO2 structure in-situ to create FexSn1-xO2 structure, which exhibits higher Li storage capacity. Our synthetic approach delivers graphene encapsulated FexSn1-xO2 structure, which is located on flexible carbonaceous fibers, and the whole system can be applied as lithium-ion batteries anode without any need of a current collector or binder polymer. This novel Sn based electrode could deliver a high capacity (calculate total electrode mass) of 454.3 mAh g−1 after 200 cycles at 100 mA g−1 (65.1% retention). Unlike most contemporary technologies, increasing the thickness of our Sn based electrode simply increases the capacity proportionally. The areal capacity is 1348.3 μAh cm−2, and it is simply doubled to 2856.1 μAh cm−2 while we double the thickness of electrode.
Recent developments in bifunctional air electrodes for unitized regenerative proton exchange membrane fuel cells – A review Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-19 M. Hunsom, D. Kaewsai, A.M. Kannan
Unitized regenerative proton exchange membrane fuel cell (UR-PEMFC) technology has progressed in the recent past and has started appearing towards few applications. However, the UR-PEMFC viability is limited by its lower round-trip efficiency mainly due to several reasons such as sluggish air electrode reactions, lower performance/stability, higher materials cost etc. In this context, many approaches are being implemented for efficiency enhancement including design and development of effective bifunctional air electrodes (oxygen reduction and evolution reactions) materials both for fuel cell and electrolyzer modes as well as for optimization of operating condition for performance stability in real life applications. This review focusses on the recent developments of air electrode active materials design/development for performance improvement in UR-PEMFC. Among all developed electrode materials, the catalysts with Pt- and Ir-based metals still provided the maximum round-trip efficiency of about 50% at 500 mA cm−2 in the unit cell.
Recent progress in efficiency of hydrogen evolution process based photoelectrochemical cell Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-20 Muhammad Zahir Iqbal, Saman Siddique
Photoelectrochemical water splitting (PEC) has emerged as an important strategy for the generation of low cost, highly efficient and sustainable hydrogen fuel. However, improvement in PEC water splitting is facing several challenges such as limited harvesting of solar light, slow charge separation rate and fast carriers recombination. Our study focuses on the brief description of PEC water splitting principle, basic working mechanism and different materials for photoanodes such as carbon and its composites, transition metals, nanomaterials and nanostructures to overcome the challenges to an extent. Numerous strategies have been discussed to investigate the performance of PEC water splitting. This work emphasized on the recent progress for sustainable hydrogen production through PEC water splitting. These photoanodic materials are good contender in future water splitting applications and enhance the overall photocurrent generation and hydrogen evolution efficiency.
Mathematical model for coal conversion in supercritical water: reacting multiphase flow with conjugate heat transfer Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-20 Zhisong Ou, Hui Jin, Zhenhua Ren, Shixing Zhu, Mengmeng Song, Liejin Guo
Providing heat for supercritical water gasification (SCWG) of coal by coupling subsequent products oxidation in integrated supercritical water reactor (ISWR) provides an effective method for directional control of temperature field and avoids excessive hot spots caused by uniform heating. An exploratory numerical model incorporating particle-fluid flow dynamics, multispecies transport and thermal coupling between endothermic coal gasification and exothermic product oxidation was established to simulate the reacting multiphase flow process of coal conversion in a novel lab-scale ISWR. An eleven-lump kinetic model was proposed for the prediction of chemical reactions. And the thermal coupling relationship was described by conjugate heat transfer boundary conditions (BC). Detailed physical and chemical field distribution in ISWR were analyzed and influence factors were discussed. The results showed that oxidation of gas products as inner heat source could promote the gasification reaction with only slight or even little maximum temperature increase of the pressure-bearing wall. Coal feeding rate and oxygen supply method significantly affected the field distribution. The multi-injection compressed-air supply method provided a more uniform temperature field but would reduce heat transfer temperature difference. The carbon gasification efficiency (CGE) in the gasification zone could easily reach up to 97% under mild conditions (less than 650 °C).
Investigation of electrospun Ba0.5Sr0.5Co0.8Fe0.2O3−δ-Gd0.1Ce0.9O1.95 cathodes for enhanced interfacial adhesion Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-20 Sanghun Lee, Kunho Lee, Sungmin Kang, Juhyun Kang, Sejin Song, Joongmyeon Bae
Fibrous Ba0.5Sr0.5Co0.8Fe0.2O3−δ-Gd0.1Ce0.9O1.95 (BSCF-GDC) composite cathodes are fabricated by a facile electrospinning method. However, the electropun BSCF-GDC cathode shows poor adhesion to a GDC electrolyte because of the high shrinkage rate of the electrospun BSCF-GDC cathode during sintering. To solve this adhesion issue, mixed BSCF fiber-GDC powder cathode is investigated. As a result, mixed BSCF fiber-GDC powder cathode with an enhanced adhesion is successfully fabricated. This improvement can be attributed to the modified microstructure with the GDC powder that joins the BSCF fibers to the GDC electrolyte at the cathode and electrolyte interface. The polarization resistance of the mixed BSCF fiber-GDC powder cathode is 0.10 Ω cm2, which is lower than 0.13 Ω cm2 of conventional BSCF-GDC powder cathode at 700 °C. It is attributable to the improved oxygen gas and lattice oxygen diffusion, and the surface exchange of the mixed BSCF fiber-GDC powder cathode. The single cell with a mixed BSCF fiber-GDC powder cathode show 500 mW cm−2 at 700 °C, which is 25% higher than conventional BSCF-GDC powder cathode.
Power-to-SNG technologies by hydrogenation of CO2 and biomass resources: A comparative chemical engineering process analysis Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-20 F. Gutiérrez-Martín, L.M. Rodríguez-Antón
Power to Synthetic-Natural-Gas (SNG) technology consists of two main steps: water electrolysis and methanation; the primary energy input is usually surplus power from renewable energy sources, while the electrolytic hydrogen and carbon oxides from different COx sources are converted into methane that can be fed in the natural gas grid. We focus on methanation technology, where the main criteria are the complexity of process setup and reactor sizes to achieve production and SNG quality for gas-grid injection. The processes are simulated using a plug-flow model for the reactors and a pseudo-homogeneous kinetic law describing the reaction of CO2 (that is rate limiting). The results show that feeding biogas or syngas (instead of CO2) for methanation has remarkable effects regarding the operation and design of the processes; it is concluded that Power-to-SNG technologies that use methane rich streams are favorable in terms of biogas upgrading, H2 requirements, reactor volumes and process simplicity, as far as these resources are available: e.g., using a typical composition (60% CH4) the required inputs are 0.96 kmol of biogas, 1.54 kmol of H2 and 0.26 m3 of reactors (two adiabatic beds with recirculation, R/F = 0.695) per kmol/min of pipeline quality dry gas product (95% CH4), which means 60% hydrogen saving, less than 26% reaction volumes and near 62% reduction of process throughput, when compared to the methanation process that uses pure CO2; conversion of syngas can be also favorable, but it requires high recirculation due to the large proportions of COx; e.g. for syngas (47.3%H2-25.9%CO-17.2%CO2-9.6%CH4), the required values mean a 53% hydrogen saving and less than 25% reaction volumes, but only 11% reduction of process throughput.
Development of a large-sized direct injection hydrogen engine for a stationary power generator Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-20 Taku Tsujimura, Yasumasa Suzuki
A number of studies on hydrogen engines have targeted small-sized engines for passenger vehicles. By contrast, the present study focuses on a large-sized engine for a stationary power generator. The objective of this study is to simultaneously achieve low NOx emission without aftertreatment, and high thermal efficiency and torque. Experimental analysis has been conducted on a single-cylinder test engine equipped with a gas injector for direct hydrogen injection. The injection strategy adopted in this study aims generating inhomogeneity of hydrogen mixtures within the engine cylinder by setting the injection pressure at a relatively low level while injecting hydrogen through small orifices. High levels of EGR and increased intake boost pressures are also adopted to reduce NOx emission and enhance torque. The results showed that extreme levels of EGR and air-fuel inhomogeneity can suppress NOx emission and the occurrence of abnormal combustion with little negative impact on the efficiency of hydrogen combustion. The maximum IMEP achieved under these conditions is 1.46 MPa (135 Nm@1000 rpm) with engine-out NOx emission of less than 150 ppm (ISNOx < 0.55 g/kW) for an intake boost pressure of 175 kPa and EGR rate of around 50%. To achieve further improvement of the IMEP and thermal efficiency, the Atkinson/Miller cycle was attempted by increasing the expansion ratio and retarding the intake valve closing time of the engine. The test engine used in this study finally achieved an IMEP of 1.64 MPa (150 Nm@1000 rpm) with less than 100 ppm of NOx emission (ISNOx < 0.36 g/kWh) and more than 50% of ITE.
Numerical modelling of release of subsonic and sonic hydrogen jets Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-21 Pratap Sathiah, Chris M. Dixon
For the general public to use hydrogen as a vehicle fuel, they must be able to handle hydrogen with the same degree of confidence as conventional liquid and gaseous fuels. For refuelling hydrogen cars, hydrogen is stored at high pressures up to 700 bar. The hazards associated with jet releases from accidental leaks of such highly pressurized storage must be considered since a jet release and dispersion can result in a fire or explosion. Therefore, it is essential to understand the dispersion characteristics of hydrogen to determine the extent of the flammable cloud when released from a high-pressure source. These parameters are very important in the establishment of the safety distances and sizes of hazardous zones. This paper describes the work done by us in modelling of dispersion of accidental releases of hydrogen, using the FRED (Fire Explosion Release Dispersion) software. The dispersion module in FRED is validated against experimental data available in the open literature for steady release and dispersion of cold and ambient hydrogen gas. The validation is performed for a wide range of hole sizes (0.5–4 mm), pressure (1.7–400 bar) and temperature (50–298 K).The model predictions of hydrogen gas jet velocity, concentration decay as a function of distance as well as radial concentration distribution are in good agreement with experiments. Overall, it is concluded that FRED can accurately model accidental release and dispersion of hydrogen in unconfined and open configurations.
Experimental studies on the catalytic behavior of alloy and core-shell supported Co-Ni bimetallic nano-catalysts for hydrogen generation by hydrolysis of sodium borohydride Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-17 Amirhossein Didehban, Mohammad Zabihi, Javad Rahbar Shahrouzi
Monometallic (Co) and bimetallic (Co-Ni and Co-Cu) oxides catalysts supported on the almond based activated carbon (AC) were prepared by the heterogeneous deposition-precipitation method. The activity of these catalysts was evaluated as a function of reaction temperature, NaOH, and NaBH4 concentration. Several analysis methods including XRD, XPS, FTIR, TEM, FESEM, ICP-OES, and BET were applied to characterize the structure of prepared samples. Well-dispersed supported bimetallic nano-catalysts with the size of particles below 20 nm were formed by using nickel and copper oxides as a promoter which was confirmed by XRD and TEM techniques. Surface composition of alloy and core-shell cobalt-nickel oxides catalysts was analyzed by ICP-OES which was in a good agreement with nominal content during catalyst preparation. The performance of bimetallic cobalt-nickel oxides catalysts indicated the synergic effect between cobalt and nickel in comparison with monometallic and bimetallic cobalt-copper samples for hydrogen production. Maximum hydrogen generation rate was measured for the supported core-shell catalyst as named Ni1/Co3/AC. The reaction rate increased with increasing the temperature of the alkaline solution as a significant parameter while other operating conditions were kept constant. The optimal values for NaOH and NaBH4 content were calculated to be 10 wt % for both variables at 30 °C. Hydrogen production rates were calculated to be 252.0, 310.8 and 658.8 mL min−1.g−1 by applying Co3/Ni1/AC, Co3-Ni1/AC (alloy) and Ni1/Co3/AC at 30 °C in 5 wt % NaBH4 and 5 wt % NaOH solutions, respectively. Obtained activation energy (50 kJ mol−1) illustrated that the suitable catalysts were synthesized for hydrogen generation. The experimental study showed that the hydrolysis of NaBH4 was a zero-order type reaction with the respect to the sodium borohydride concentration. A semi empirical kinetic model was derived at the various temperatures and NaOH concentrations.
Adsorption behavior and kinetics of H2S on a potassium-promoted hydrotalcite Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-16 Kai Coenen, Fausto Gallucci, Emiel Hensen, Martin van Sint Annaland
Catalytic effect of MgFe2O4 on the hydrogen storage properties of Na3AlH6–LiBH4 composite system Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-16 F.A. Halim Yap, N.A. Ali, N.H. Idris, M. Ismail
The effect of MgFe2O4 on the hydrogen storage properties of the composite Na3AlH64LiBH4 was studied for the first time, where it was found that MgFe2O4 addition decreased the onset desorption temperature of Na3AlH64LiBH4. Hydrogen (∼9.5 wt%) was released in three stages and the dehydrogenation temperatures were reduced to 80 °C, 350 °C, and 430 °C for the first, second, and third stage, respectively. The absorption kinetics of Na3AlH64LiBH4 was also significantly improved due to the catalytic effect of MgFe2O4. Using Kissinger analysis, the apparent activation energies of decomposition of the Li3AlH6 and NaBH4 stages in Na3AlH64LiBH4-10 wt% MgFe2O4 were calculated to be 72 and 141 kJ/mol, respectively. These values were considerably lower than the corresponding values for the undoped composite. X-ray diffraction analysis revealed the formation of new products such as MgO and Fe during the heating process. Our results suggest that MgFe2O4 enhanced the hydrogen storage properties of Na3AlH64LiBH4 through the formation of active species, such as MgO and Fe.
Cu2ZnSnS4 decorated CdS nanorods for enhanced visible-light-driven photocatalytic hydrogen production Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-16 Meng Yuan, Wen-Hui Zhou, Dong-Xing Kou, Zheng-Ji Zhou, Yue-Na Meng, Si-Xin Wu
Facile and large-scale preparation of Co/Ni-MoO2 composite as high-performance electrocatalyst for hydrogen evolution reaction Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-16 Bo Xu, Yiqiang Sun, Zhiming Chen, Shuying Zhao, Xiaodong Yang, Haijing Zhang, Cuncheng Li
Facile fabrication of high-performance catalyst based on low-cost metals for sustainable hydrogen evolution is still a matter of cardinal significance. However, synthetic approaches for electrocatalyst are usually complicated and the yields are often low. Herein, we report a one-step simple method for the large-scale synthesis of Co/Ni-MoO2 composite as efficient and stable hydrogen evolution reaction (HER) electrocatalyst to drive 10 mA cm−2 current density with a low overpotential of 103 mV in basic media. Co-MoO2 and Ni-MoO2 were also prepared using this method with overpotential of 137 and 130 mV, respectively, to gain the same current density. These results indicate that this facile synthesis approach is of great practical importance as it can be easily used for large-scale preparation of electrocatalysts in industry.
Synthesis of PdV/C nanoparticles using phase transfer method for oxygen reduction in alkaline electrolytes Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-16 Biyao Jin, Yiqi Li, Lianhua Zhao
Hydrogen isotopes separation validation of frontal displacement chromatography for various compositions of feed gas and tritium extraction simulation for TBM Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-16 Xiaojun Deng, Deli Luo, Cheng Qin, Daqiao Meng, Tao Tang, Wenhua Luo
Based on the previous study in frontal displacement chromatography (FDC) packed with Pd-Al2O3, three groups of separation tests were carried out to verify the separation performance of the constituted FDC device for various compositions of feed gas and to validate the application probability of FDC in the Tritium Extraction System (TES) of ITER and China Fusion Engineering Test Reactor (CFETR). The separations were conducted by the FDC procedure with characteristics of the feed gas one-time flushing though the column and then reasonable separation performance had been obtained. The results indicate that the FDC process could be applied to deal with the desorbed gas mixtures from TES and/or further to extract and thereafter enrich the breeding tritium in ITER or CFETR, which would take the advantages of system compactness and efficiency over the present route of TES. Comparing to other related displacement chromatography procedures, the FDC process could be applied in tritium pre-enrichment for the mixtures of low tritium concentrations, which is highlighted by the outstanding merit of operation simplicity.
A numerical study of the combustion and jet characteristics of a hydrogen fueled turbulent hot-jet ignition (THJI) chamber Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-16 Nana Wang, Jinxiang Liu, Wayne L. Chang, Chia-fon Lee
Turbulent hot-jet ignition (THJI) is an advanced ignition enhancement technology which can potentially overcome the problem associated with lean burn combustion. The present study makes an effort on the comprehensive understanding of a hydrogen fueled THJI chamber with various pre-chamber spark locations. Computational fluid dynamics (CFD) simulations are performed using an in-house code based on the KIVA-3V release 2 program coupled with an in-house chemical solver. A detailed chemical kinetics mechanism with 10 species and 19 reversible reactions is used for the H2/air mixture in both the pre-chamber and the main chamber. The results show that moving the spark ignition location farther from the orifice significantly reduces the 0−10% mass fraction burn period. By analyzing the local Mach number, turbulence kinetic energy and turbulence length scale, the compressibility and turbulence level of the jet flow are evaluated. Further analysis of the OH mass fraction distribution identifies three regions in the hot jet, i.e. extinction region, just-igniting region and combustion region. A critical Damköhler number of 0.3 is determined to separate the extinction region from the other regions. Meanwhile, transition Damköhler numbers ranging from 0.3 to 0.6 are determined in the just-igniting region.
CoSe2 nanoparticles grown on carbon nanofibers derived from bacterial cellulose as an efficient electrocatalyst for hydrogen evolution reaction Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-16 Licheng Wei, Jiaxian Luo, Lijuan Jiang, Lijun Qiu, Jinming Zhang, Dawei Zhang, Peiman Xu, Dingsheng Yuan
Exploration of high-efficiency and inexpensive Pt-free electrochemical catalysts for hydrogen evolution reaction (HER) is highly significative for carbon dioxide free energy conversion systems. In this work, we described the development of CoSe2 nanoparticles grown on the carbon nanofibers (CNFs) derived from bacterial cellulose (CNFs/CoSe2) through a facile one-step hydrothermal preparation, which not only showed a three-dimensional (3D) porous network structure, but also possessed large surface area. This rationally designed architecture realizes the uniform distribution of CoSe2 nanoparticles to provide with fully exposed active edges and the unique conductive interwoven carbon nanofibers facilitates the charge transportation in HER process, thus leading to remarkable HER activity. As expected, the CNFs/CoSe2 shows a low onset overpotential of −85 mV, low overpotential (η10 = 119 mV) for reaching a current density of −10 mA cm−2 and smaller Tafel slope of 54 mV dec−1 as well as good cycling stability in acidic electrolyte.
Numerical investigation of coal gasification in supercritical water with the ReaxFF molecular dynamics method Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-17 Hanhui Jin, Bonan Xu, Hanqing Li, Xiaoke Ku, Jianren Fan
Studies on the coal gasification process in supercritical water (SCW) were carried out with the ReaxFF molecular dynamics (MD) method, in which the Wiser model of the coal molecule was adopted. The results show that hydrogen production increases with increase of temperature and water–coal mass ratio. It is also found that the coal molecule breaks into small fragments before it reacts with water molecules. The detailed chemical reactions and pathways of hydrogen generation during the gasification process are disclosed. H ions are found to be the main source of hydrogen generation, and C–H–O compounds or radicals are the most essential reactants throughout the reactions producing H2 and H ions. OH ions can significantly accelerate the oxidization of organic fragments to produce C–H–O compounds and radicals, which explains how catalysts of alkali salts such as NaOH and KOH improve hydrogen production.
Enhancement of the quality of syngas from catalytic steam gasification of biomass by the addition of methane/model biogas Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-17 Yalan Shen, Yang Liu, Haimiao Yu
In this study, methane and model biogas were added during the catalytic steam gasification of pine to regulate the syngas composition and improve the quality of syngas. The effects of Ni/γ-Al2O3 catalyst, steam and methane/model biogas on H2/CO ratio, syngas yield, carbon conversion rate and tar yield were explored. The results indicated that the addition of methane/model biogas during biomass steam gasification could increase the H2/CO ratio to about 2. Methane/model biogas, steam and Ni/γ-Al2O3 catalyst significantly affected the quality of syngas. High H2 content syngas with H2/CO ratio of about 2, biomass carbon conversion >85% and low tar yield was achieved under the optimum condition: S/C = 1.5, α = 0.2 and using Ni/γ-Al2O3 catalyst. According to ANOVA, methane and catalyst were the key influencing factors of the H2/CO ratio and syngas yield, and the tar yield mainly depended on the Ni/γ-Al2O3 catalyst. Biogas, as a more environmentally friendly material than methane, can also regulate the composition of syngas co-feeding with biomass.
Thermal decomposition behavior of nickel-iron hydrotalcite and its electrocatalytic properties of oxygen reduction and oxygen evolution reactions Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-17 Zejie Zhang, Debi Zhou, Xinjun Bao, Huazhang Yu, Boyun Huang
The thermal decomposition behavior of NiFe layered double hydroxide (LDH) was investigated by thermogravimetric analysis-differential scanning calorimetry (TG-DSC). The calcined product at 500 °C was mainly NiO/FeOx composite oxide, of which FeOx was amorphous oxide; the calcined product at 650 °C was mainly NiO/NiFe2O4 composite oxide. The polarization curves and chronopotentiometry stated that the NiO/FeOx and NiO/NiFe2O4 showed good electrocatalytic OER and ORR activity; the OER activity of NiO/FeOx was better than that of NiO/NiFe2O4; the ORR activity of NiO/NiFe2O4 was better than that of NiO/FeOx.
Hydrogen storage in porous geological formations – onshore play opportunities in the midland valley (Scotland, UK) Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-17 N. Heinemann, M.G. Booth, R.S. Haszeldine, M. Wilkinson, J. Scafidi, K. Edlmann
Hydrogen usage and storage may contribute to reducing greenhouse gas emissions by decarbonising heating and transport and by offering significant energy storage to balance variable renewable energy supply. Underground storage of hydrogen is established in underground salt caverns, but these have restricted geographical locations within the UK and cannot deliver the required capacity. Hydrogen storage in porous geological formations has significant potential to deliver both the capacity and local positioning. This study investigates the potential for storage of hydrogen in porous subsurface media in Scotland. We introduce for the first time the concept of the hydrogen storage play. A geological combination including reservoir, seal and trap that provides the optimum hydrogen storage reservoir conditions that will be potential targets for future pilot, and commercial, hydrogen storage projects. We investigate three conceptual hydrogen storage plays in the Midland Valley of Scotland, an area chosen primarily because it contains the most extensive onshore sedimentary deposits in Scotland, with the added benefit of being close to potential consumers in the cities of Glasgow and Edinburgh. The formations assessed are of Devonian and Carboniferous age. The Devonian storage play offers vast storage capacity but its validity is uncertain due to due to a lack of geological data. The two Carboniferous plays have less capacity but the abundant data produced by the hydrocarbon industry makes our suitability assessment of these plays relatively certain. We conclude that the Carboniferous age sedimentary deposits of the D'Arcy-Cousland Anticline and the Balgonie Anticline close to Edinburgh will make suitable hydrogen storage sites and are ideal for an early hydrogen storage research project.
Copper oxide hollow spheres: Synthesis and catalytic application in hydrolytic dehydrogenation of ammonia borane Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-17 Xiaoge Feng, Xi-Meng Chen, Pengtao Qiu, Dapeng Wu, Ewan J.M. Hamilton, Jie Zhang, Xuenian Chen
Solvent effect in the synthesis of nanostructured Pt–Sn/CNT as electrocatalysts for the electrooxidation of ethanol Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-15 Luis A. Romero-Cano, G. Rosado-Ortiz, A.M. Valenzuela-Muñiz, L.C. Ordóñez, R. Gauvin, Y. Verde Gómez
Co3O4@g-C3N4 supported on N-doped graphene as effective electrocatalyst for oxygen reduction reaction Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-16 Yanqiu Wang, Xiang Yin, Haibo Shen, Hao Jiang, Jiawen Yu, Yafei Zhang, Dongwei Li, Wenzhang Li, Jie Li
LaCoO3-δ-coated Ba0.5Sr0.5Co0.8Fe0.2O3-δ: A promising cathode material with remarkable performance and CO2 resistance for intermediate temperature solid oxide fuel cells Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-16 Peng Qiu, Ao Wang, Haoyu Zheng, Lichao Jia, Bo Chi, Jian Pu, Jian Li
LaCoO3-δ (LC)-coated Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) cathode is fabricated by the solution impregnation method and promoted electrochemical performance is obtained. After being coated by LC shell, the polarization resistance can be as low as 0.197 Ω cm2 and the peak power density is 0.243 W cm−2 at the operating temperature of 600 °C. The excellent CO2 resistance of LC-coated BSCF cathode is verified by the CO2-poisoning test. Even in the operating atmosphere with high CO2 concentration, the polarization resistance change of LC-coated BSCF cathode is much smaller than that of the blank BSCF cathode. By long-term test of single cells, the remarkable electrochemical performance stability of LC-coated BSCF cathode is shown. The promoted electrochemical performance, excellent CO2 resistance and remarkable long-term stability make LC-coated BSCF cathode promising for intermediate temperature solid oxide fuel cells.
Investigations on the influence of ethanol and water injection techniques on engine's behavior of a hydrogen - biofuel based dual fuel engine Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-16 M. Senthil Kumar, S.V. Karthic, P. Pradeep
This work explores the influence of hydrogen and ethanol on improving engine's behavior of Maduca longifolia oil (MO) based dual fuel diesel engine. A mono cylinder diesel engine was tested in dual fuel mode of operation at the rated power output of 3.7 kW under variable hydrogen energy shares from 0 to the maximum allowable limit (until severe knocking i.e. upto 20%). The knock limit was further extended by injecting water and ethanol at the intake manifold and the engine's performance, emission and combustion characteristics were analyzed. In addition ethanol was also injected and introduced along with the intake air for comparison with hydrogen dual fuel mode. Dual fuel operation increased the BTE from 25.2% with neat MO to a maximum of 28.5% and 30% respectively with hydrogen and ethanol for the energy share of 15% and 38% where as the BTE was 30.8% with ND. The smoke opacity was reduced from 78% with neat MO to 58% for the hydrogen energy share of 15% which is the MEP (maximum efficiency point) whereas the smoke emission was noted as 51% with ND operation. However, hydrogen induction increased the NO (nitric oxide) emission. Injection of water and ethanol at the inlet was observed to extend the knocking limit with improved BTE. The BTE reached a maximum of 30.1% with 5% water and 30.8% with 10% ethanol injection. The MEPs were arrived as 31% and 30% hydrogen energy shares respectively with 5% water and 10% ethanol injection. It was concluded that hydrogen induction can be very effective in improving the diesel engine's performance when using MO as base fuel when operating on dual fuel mode. The performance could be improved by extending the knock limit by injecting ethanol and water along with hydrogen.
Numerical simulation and analysis of thermal stress distributions for a planar solid oxide fuel cell stack with external manifold structure Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-15 Cun Wang, Jia jun Yang, Wei Huang, Tao Zhang, Dong Yan, Jian Pu, Bo Chi, Jian Li
A three-dimensional numerical model based on the finite element method (FEM) is constructed to calculate the thermal stress distribution in a planar solid oxide fuel cell (SOFC) stack with external manifold structure. The stack is composed of 5 units which include cell, metallic interconnect, seal and anode/cathode current collectors. The temperature profile is described according to measured temperature points in the stack. It can be clearly seen that the maximum stress concentration area appears at the corner of the components when the stack is heated from room temperature (RT) to 780 °C. The effects of stack components on maximum stress concentration have been investigated under the operation temperature, as well as the thermal stress simulation results. It is obvious that the coefficient of thermal expansion (CTE) mismatch between the interconnect and the seal plays an important role in determining the thermal stress distribution in the stack. However, different compressive loads have almost no effect on stress distribution, and the influence of glass-based seal depends on the elastic modulus. The simulation results can be applied for optimizing the structural design of the stack and minimizing the high stress concentration in components.
Analysis of shaking effect on photo-fermentative hydrogen production under different concentrations of corn stover powder Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-15 Shengnan Zhu, Zhiping Zhang, Yameng Li, Nadeem Tahir, Huiliang Liu, Quanguo Zhang
High solid phase and easily congeal affect the mass transfer in the photo-fermentative biohydrogen production when taken straw biomass as substrate. Hence, oscillator was adopted to provide the shaking condition to enhance the mass transfer situation in this paper. Diverse shaking velocity (0, 80, 120 and 160 rpm) and substrate concentration (0, 2, 4, 6, 8 and 10 g) were studied, to evaluate the influence on the hydrogen yield capacity. The results showed that shaking could help to accelerate of gas release, shorten the fermentation time, and improve hydrogen production rate. Hydrogen yield was significantly enhanced at high substrate concentration under shaking condition. Highest hydrogen yield of 57.08 ± 0.83, 57.62 ± 1.37, 62.28 ± 0.84 mL/g-volatile solids (VS) were observed at shaking velocities of 80, 120 and 160 rpm with 6, 8 and 10 g corn stover powder, respectively. On the contrary, shaking significantly reduced the potential of hydrogen yield at a low substrate concentration, and the lower hydrogen yield obtained at the higher shaking velocity. As the lowest hydrogen yields of 27.68 ± 1.02 and 41.93 ± 0.40 mL/g VS were obtained at shaking velocity of 160 rpm with 2 and 4 g corn stover powder, respectively.
Improvement in the activity of Pt1Ni3/C by decorating with Au adatoms for ethylene glycol oxidation Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-15 Nan Cai, Jialu Wu, Rulin Dong, Changchun Jin
The decoration of Pt1Ni3 nanoparticles supported on carbon black with Au adatoms and the electrocatalytic activity of the Au-decorated Pt1Ni3/C (Au/Pt1Ni3/C) for the oxidation of ethylene glycol (EG) in alkaline solution have been investigated. The decoration of Pt1Ni3/C with Au is performed by potentiostatically depositing a small amount of Au on Pt1Ni3/C, and the Au/Pt1Ni3/C catalysts with Au/Pt atomic ratios of ca. 0.02:1 and 0.08:1 are obtained. Physical and electrochemical characterizations reveal that a small part of the surface of Pt1Ni3 nanoparticles is covered by Au adatoms. In EG oxidation, the performances of Pt1Ni3/C before and after the Au decoration are quite different. Au/Pt1Ni3/C shows remarkably high peak intensity compared to Pt1Ni3/C, in spite of a decrease in the surface of Pt by Au adatoms. The low Pt content of Pt1Ni3 nanoparticles and the small Au loading also suggest advantages of the Au/Pt1Ni3/C catalysts in cost. The result of this study reveals a significant enhancing effect of Au adatoms on the activity of Pt1Ni3/C for EG oxidation.
Cobalt phosphide nanoparticles anchored on molybdenum selenide nanosheets as high-performance electrocatalysts for water reduction Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-15 Chaoying Ding, Jiahui Qian, Zhen Li, Yang Li, Wenchao Peng, Guoliang Zhang, Fengbao Zhang, Xiaobin Fan
Cobalt phosphide (CoP) has been regarded as one of the most promising electrocatalysts to generate hydrogen gas by splitting water. However, the electrocatalytic performance of CoP is hindered by its relatively sluggish kinetics. Herein, a novel and effective electrocatalyst based on MoSe2 nanosheets combining with CoP has been synthesized via a facile method. By electrochemistry test, it is found that all the composites display much better catalytic activities than pristine CoP and pure MoSe2 nanosheets. In addition, the optimized composite can realize a current density of 155.14 mA/cm2 at the potential of −300 mV vs RHE and exhibit outstanding stability. This remarkable HER activity may result from the excellent electrical conductivity of MoSe2 nanosheets and the synergistic effect between MoSe2 nanosheets and CoP.
Structure of V-doped Pdn (n = 2–12) clusters and their ability for H2 dissociation Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-12 P.L. Rodríguez-Kessler, Fernando Murillo, A.R. Rodríguez-Domínguez, Pedro Navarro-Santos, Gabriel Merino
A complementary study on novel PdAuCo catalysts: Synthesis, characterization, direct formic acid fuel cell application, and exergy analysis Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-12 Hilal Kivrak, Dilan Atbas, Orhan Alal, M. Selim Çögenli, Ayse Bayrakceken, Suha Orcun Mert, Ozlem Sahin
Performance evaluation of hematite oxygen carriers in high purity hydrogen generation from cooking oil by chemical looping reaction Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-12 Guoqiang Wei, Xianshuang Wu, Junguang Meng, Zhen Huang, Fang He, Weina Zhao, Kun Zhao, Anqing Zheng, Zengli Zhao, Haibin Li
Bottom-up cost evaluation of SOEC systems in the range of 10–100 MW Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-12 Régis Anghilante, David Colomar, Annabelle Brisse, Mathieu Marrony
A detailed bottom-up cost evaluation of SOEC systems in the range of 10–100 MW was carried out based on recent experimental results in the SOEC field. Capital costs of installed SOEC systems were evaluated starting from raw SOEC materials. Two scenarios were defined, assuming different capacities of SOEC units, yearly production capacities of SOEC cells and stacks as well as operating conditions of manufacturing lines. It resulted in installed capital costs of 309–395 €/kW for SOEC units integrated into power-to-methane plants (reference case) and of 380–494 €/kW for stand-alone SOEC units. This highlights the cost reduction potential of the SOEC technology when thermally coupled with a steam source. These costs were compared with previous capital cost estimates for future SOEC, proton exchange membrane (PEM) and alkaline electrolysis systems available in the literature. A sensitivity analysis allowed to identify which parameters have the highest impact on installed system costs. In the least favorable conditions, it was estimated that they could raise up to 494–618 €/kW for SOEC units in the reference case and up to 573–727 €/kW for stand-alone SOEC units.
Building evaluation model of biohydrogen industry with circular economy in Asian countries Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-13 Duu-Hwa Lee
This investigation contributes to the relevant literature by building a preliminary economic model of the biohydrogen with circular economy (CE) to evaluate the effects of developing biohydrogen which is an important driven power of CE. Value flows of secondary materials are estimated and added to the IO database and circularity are also added to GTAP model. The results demonstrate that the GTAP model modified with biohydrogen of CE is valid. Malaysia will be the most productive country if it developed CE, and it will have the highest output value of biohydrogen industry compared to other countries. CE will outperform LE in developed regions, whereas LE will outperform CE in developing regions. Japan will be the first country to realize CE with negative CE gap. The results for Japan indicate the effectiveness of the modification of GTAP model to incorporate CE mechanism and biohydrogen. The biohydrogen industry will have an important role in the transition to CE.
Performance assesment of hydrogen and ammonia combustion with various fuels for power generators Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-13 Arda Yapicioglu, Ibrahim Dincer
This paper proposes the use of hydrogen and ammonia as possible fuels for power generators and to do so the combustion is modelled by using different types of fuels which are; hydrogen, gasoline, diesel, ethanol, methanol, propane, butane and natural gas to see the effects of these fuel sources on combustion. The main aim of using a clean fuel is to decrease the greenhouse emissions, and by looking at the results, the reduction in CO2 emissions shows that blending hydrogen and ammonia will result in a reduction for the deleterious emissions occurring after combustion. The reason behind using a dual fueled system is to make use of the secondary fuel source as a combustion promoter to help increase the low flame temperatures of ammonia that causes it not to ignite when used solely. In the modelling of combustion the maximum power output is set to 3.65 kW as this is the maximum power output for the power generator used in the experimental studies. In the studies the increase of clean fuel percentage in the fuel blend cause a reduction in the performance measures as expected with the lower energy density and lower heating values that ammonia offers but the reduction in CO2 and NOx emissions makes it a fuel source worth using with a combustion promoter.
Porous nickel-iron alloys as anode support for intermediate temperature solid oxide fuel cells: II. Cell performance and stability Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-14 Xin Wang, Lichao Jia, Kai Li, Dong Yan, Bo Chi, Jian Pu, Li Jian
Porous nickel–iron alloy supported solid oxide fuel cells (SOFCs) are fabricated through cost-effective ceramic process including tape casting, screen printing and co-sintering. The cell performance is characterized with humidified hydrogen as the fuel and flowing air as the oxidant. Effects of iron content on the cell performance and stability under redox and thermal cycle are investigated from the point of view of structural stability. Single cells supported by nickel and nickel–iron alloy (50 wt % iron) present relatively high discharge performance, and the maximum power density measured at 800 °C is 1.52 and 1.30 W cm−2 respectively. Nickel supported SOFC shows better thermal stability between 200 and 750 °C due to its dimensional stable substrate under thermal cycles. Posttest analysis shows that a dense iron oxide layer formed on the surface of the nickel-iron alloy during the early stage of oxidation, which prevents the further oxidation of the substrate as well as the functional anode layer, and thus, making nickel-iron supported SOFC exhibits better redox stability at 750 °C. Adding 0.5 wt % magnesium oxide into the nickel-iron alloy (50 wt% iron) can inhibit the metal sintering and reduce the linear shrinkage, making the single cell exhibit promising thermal stability.
Synthesis and properties of new side-chain-type poly(arylene ether sulfone)s containing tri-imidazole cations as anion-exchange membranes Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-14 Chenyi Wang, Yuanpeng Zhou, Chang Xu, Xiaoyan Zhao, Jian Li, Qiang Ren
Influence of operating variables on the aqueous-phase reforming of glycerol over a Ni/Al coprecipitated catalyst Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-11 L. García, A. Valiente, M. Oliva, J. Ruiz, J. Arauzo
Hydrogen permeation properties of CrxCy@Cr2O3/Al2O3 composite coating derived from selective oxidation of a CrC alloy and atomic layer deposition Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-11 Jipeng Wang, Zhaoxia Lu, Yunhan Ling, Rongguang Wang, Yunhui Li, Qingyun Zhou, Zhengjun Zhang
Metal oxides and carbides are promising tritium permeation barrier coatings for fusion reactors. However, the thermomechanical mismatch between the coating and substrate poses a threat to their interface's integrity during fabrication and operation. To address this issue, a metallic interlayer coating was introduced followed by selective oxidation in which a compact and uniform CrC amorphous alloy coating was successfully deposited on the stainless steel substrate by pulsed electrochemical deposition. A new composite coating of CrxCy@Cr2O3/Al2O3 was formed by subsequent controlled oxidation conversion and atomic layer deposition. The phase, morphology, chemical state and defects of the films were analyzed and compared both before and after hydrogen exposure at 300 °C. The results show that this new kind of composite coating, based on the principles of grain boundary pinning of chromic oxide with carbide and defect healing of alumina, can remarkably improve the hydrogen permeation barrier performance of these materials.
Investment screening model for spatial deployment of power-to-gas plants on a national scale – A Danish case Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-11 Steffen Nielsen, Iva Ridjan Skov
When transitioning to a 100% renewable energy system storing electricity becomes a focal point, as the resource flexibility is lost and the design of the energy system needs to provide flexibility and balancing options to integrate intermittent renewable resources. Using technologies such as power-to-gas offers an opportunity to store electricity in chemical form, which can be used as a long-term storage option. This paper develops a spatial modelling method by using a GIS tool to investigate potential generation sites for power-to-gas plants. The method determines the location of the plants by carbon source potential, proximity of the grid, costs of grid transmission and investment costs of the technology itself. By combining these types of data, it is possible to identify the investment costs of the power-to-gas plants. The method focuses on two paths: biogas upgrade and CO2 methanation. The method is applied to a specific case by investigating the power-to-gas potential in Denmark. The potential and spatial deployment is found by examining the investment costs of plants with an annual gas production of 60 GWh. The findings of the analysis indicate that the biogas upgrade path is the cheapest one of the two, at the present cost level, but due to the relatively small number of biogas plants in Denmark, the chosen plant size is limited to around 55 plants. CO2 methanation is a more costly path, but it has a larger potential of around 800 plants. As the analysis is based on the current sources for biogas and CO2, it is important to emphasise that the potential for CO2 methanation plants can be expected to diminish in the future as more renewable energy is introduced, lowering the need for thermal energy producers, while biogas production could see an increase. Nevertheless, the analysis of a specific case shows that the method gives a good indication of the extent of the power-to-gas resources by using a novel approach to the matter. The method can be applied in other countries as well, giving it a wide appeal.
Facile synthesis of BSCF perovskite oxide as an efficient bifunctional oxygen electrocatalyst Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-12 Uday Pratap Azad, Monika Singh, Sourav Ghosh, Ashish Kumar Singh, Vellaichamy Ganesan, Akhilesh Kumar Singh, Rajiv Prakash
The optimization of electrolyte composition for CH4 and H2 generation via CO2/H2O co-electrolysis in eutectic molten salts Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-12 Deqiang Ji, Zhida Li, Wei Li, Dandan Yuan, Yuhang Wang, Yanyan Yu, Hongjun Wu
A huge number of carbon dioxide (CO2) emission is beyond the scope of the natural changes of the earth itself and destabilizes the carbon cycle, which leads to worsening global warming problem, and also seriously threats the survival and development of human. Herein, CO2 is captured and transformed electrochemically with H2O to controllably generate CH4 and H2 in an electrolyte comprising a eutectic of carbonates and hydroxides with equal-area Fe cathode and Ni anode. Gas chromatography (GC) is employed to analyze the content of gaseous products. Additionally, Faraday efficiency under different conditions is measured via the comparison between moles of obtained fuel gas (mainly composed of CH4 and H2) and the Faradays of charge passed during the electrolysis reaction. This article investigates the effect of molten salt compositions on gaseous product generation, and confirms the visible dependence of obtained products on the electrolytes.
Experimental investigation on the temperature and heat-transfer characteristics of rotating-detonation-combustor outer wall Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-12 Shengbing Zhou, Hu Ma, Chuan Liu, Changsheng Zhou, Daokun Liu
The thermal management on rotating detonation engine is attracting much attention in recent years. In this study, the experiments were performed on a rotating detonation combustor to study the temperature and heat-transfer characteristics of the outer wall. Hydrogen, which was used as fuel, was injected into chamber through 120 orifices uniformly distributed in front of combustor, and air, which was functioned as an oxidiser, was injected into combustion chamber through an annular slot. An infrared thermal imaging was used to measure the temperature of outer wall. All the experimental test cases could obtain a stable rotating detonation wave, and the hot-gas temperature decreased with the increase of axial-direction length. The temperature initially increased and then decreased from the head of the wall towards the back. The heat which transferred from the hot gas to the outer wall was further large than the value of losing during the combustor operation, resulting in an approximately linear relationship for the temperature rise. There was a similar distribution trend for the outer-wall heat flux under the conditions of different equivalence ratios, and the location of 20% distance, relative to combustor length, had a biggest heat flux.
Techno-economic feasibility of power to gas–oxy-fuel boiler hybrid system under uncertainty Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-12 Manuel Bailera, Dawid P. Hanak, Pilar Lisbona, Luis M. Romeo
One of the main challenges associated with utilisation of the renewable energy is the need for energy storage to handle its intermittent nature. Power-to-Gas (PtG) represents a promising option to foster the conversion of renewable electricity into energy carriers that may attend electrical, thermal, or mechanical needs on-demand. This work aimed to incorporate a stochastic approach (Artificial Neural Network combined with Monte Carlo simulations) into the thermodynamic and economic analysis of the PtG process hybridized with an oxy-fuel boiler (modelled in Aspen Plus®). Such approach generated probability density curves for the key techno-economic performance indicators of the PtG process. Results showed that the mean utilisation of electricity from RES, accounting for the chemical energy in SNG and heat from methanators, reached 62.6%. Besides, the probability that the discounted cash flow is positive was estimated to be only 13.4%, under the set of conditions considered in the work. This work also showed that in order to make the mean net present value positive, subsidies of 68 €/MWelh are required (with respect to the electricity consumed by PtG process from RES). This figure is similar to the financial aids received by other technologies in the current economic environment.
Transformation of biomass into carbon nanofiber for supercapacitor application – A review Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-12 Elfina Azwar, Wan Adibah Wan Mahari, Joon Huang Chuah, Dai-Viet N. Vo, Nyuk Ling Ma, Wei Haur Lam, Su Shiung Lam
Steam reforming of acetic acid for hydrogen production over attapulgite and alumina supported Ni catalysts: Impacts of properties of supports on catalytic behaviors Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-12 Chenting Zhang, Xun Hu, Zhenjie Yu, Zhanming Zhang, Guozhu Chen, Cuncheng Li, Qing Liu, Jun Xiang, Yi Wang, Song Hu
Evaluation of performance improvement by model predictive control in a renewable energy system with hydrogen storage Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-12 David Morin, Yoann Stevenin, Cédric Grolleau, Pascal Brault
Nowadays islanded microgrids mostly rely on diesel generator. In order to reduce greenhouse emissions, two islanded microgrids with hydrogen storage have been installed and are currently working autonomously in Reunion Island and France. Energy management implemented on these stations fall in the myopic control category. This study aims to determine the performance improvement that could be achieve on such stations using model predictive control. Ability to supply to the loads and energy losses minimisation are our main objectives. Lifetime degradation is also taken in consideration. Simulations shows that significant improvement can be brought, with a 76% decrease of the station's defaults time and better fill rate of hydrogen tank and batteries. In the meantime, chemical and electrical losses are reduced by 38 and 11%, and the batteries degradations are decreased by around 1%. The relevance of taking into account the electrolyser and fuel cell degradations depends on the time-step of the control. These results give a performance target in order to implement a real-time model predictive control in the microgrids, and eventually can be used to better sizing of future microgrids with similar architecture.
A coupled power-voltage equilibrium strategy based on droop control for fuel cell/battery/supercapacitor hybrid tramway Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-11 Guorui Zhang, Qi Li, Weirong Chen, Xiang Meng, Huiwen Deng
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.
Impact of urban development on residents’ public transportation travel energy consumption in China: An analysis of hydrogen fuel cell vehicles alternatives Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-11 Xiaoying Chang, Tao Ma, Ran Wu
Urban development has an important influence on the energy consumption of transportation. To develop public transportation is one of the important ways to decrease the energy consumption of urban transportation. It is very urgent to upgrade technology to reduce the energy consumption and emissions of the vehicles constantly. The popularization of hydrogen fuel cell vehicles is the trend of the future automobile industry, which can effectively reduce traffic energy consumption and alleviate urban pollution. This article analyzes the impact of urban development on public transport and private transportation energy consumption from 2013 to 2015; and uses hydrogen fuel cell vehicles alternatives in urban public transport as a scenario. It shows that urban economic development can effectively reduce public transport. Population growth will increase greatly energy consumption of public transport, while larger cities with reasonable spatial density can reduce traffic energy consumption. Moreover, hydrogen fuel cell vehicles can effectively reduce the energy consumption and pollution emissions of urban transportation during operating. Based on the above conclusions, this article will eventually provide targeted recommendations for the development of Chinese cities, public transport, and hydrogen fuel cell vehicles.
Theoretical study on the effect of an O vacancy on the hydrogen storage properties of the LaFeO3 (010) surface Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-11 Yuhong Chen, Jiajia Fan, Tingting Liu, Jing Wang, Meiling Zhang, Cairong Zhang
Based on first-principles calculations, we investigated the hydrogen adsorption dissociation on the LaFeO3 (010) surface with an O vacancy. It was confirmed that H2 molecules have four kinds of adsorption modes on LaFeO3 (010) surfaces with an O vacancy. First, H atoms are adsorbed on O atoms to form an OH group. Second, H atoms are adsorbed on Fe atoms to form FeH bonds. Third, two H atoms are adsorbed on the same O atom to form H2O. Fourth, two H atoms are adsorbed on the same Fe atom and it is a new type of adsorption, which does not exist in the ideal surface. The main channel of dissociative adsorption is the fourth adsorption mode of OH and FeH, where the H atoms adsorbed on the surface of Fe can be easily diffused into O atoms. Charge population analysis showed that increasing the O vacancy enhanced the interaction between FeH. In the system containing O vacancies adsorbed H atoms in the top of Fe to diffuse to the top of O need to overcome the energy barrier decreased from 0.968 eV to 0.794 eV. So the existence of an O vacancy enhances the hydrogen absorption properties of Fe atoms in LaFeO3.
Effects of reformed exhaust gas recirculation on the HC and CO emissions of a spark-ignition engine fueled with LNG Int. J. Hydrogen Energy (IF 4.229) Pub Date : 2018-10-11 Yanxiang Long, Gesheng Li, Zunhua Zhang, Junjie Liang, Litong Mao, Yeyuan Li
Reformed exhaust gas recirculation (REGR), which can generate onboard hydrogen-rich gas (i.e., the reformate including H2, CO, unreformed hydrocarbon, etc.) via catalytic reforming of fuel and engine exhaust gas, is an attractive way to improve the performance and emissions characteristics of the engine fueled with liquefied natural gas (i.e., NG engine). However, the leakage during the valve overlap period and incomplete burning of the added reformate may lead to extra HC and CO emissions from the engine with REGR. In the present study, a multi-dimensional computation fluid dynamics model coupled with a detailed chemical kinetic mechanism was developed to investigate the effects of the ratio of reformate addition (Rref) and exhaust valve closed (EVC) timing on the total emissions characteristics as well as the sources of HC and CO emissions from the engine. The emissions from the combustion and the leaking were included to calculate the total emissions. Moreover, the unburned CO from the added reformate was distinguished from the total CO emissions by adding marked-species. Results show that the unburned CH4 in the cylinder is the main component of the total CH4 emissions. Due to the increase of the concentrations of OH, O and H radicals during the combustion process, the oxidization of CH4 is promoted with the increase of Rref at high load, and therefore the total CH4 emissions decrease. However, the total CO emissions increase with the increase of Rref, and it is demonstrated that the unburned CO from the added reformate increases and turns to be the main sources of the total CO emissions. At Rref of 10%, the total CH4 and CO emissions firstly remain nearly constant and then increase dramatically with the delay of EVC timing. Therefore, low concentration of CO in the reformate and short valve duration are recommended to achieve low HC and CO emissions for the NG engine with REGR.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
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