Papers by Keyword: Hydrogen Energy

Abstract: As a clean and efficient renewable energy, hydrogen energy will play an important role in the future energy system. The utilization of hydrogen energy involves various fields including production, application, storage and transportation, and the storage of hydrogen has become the main technical bottleneck restricting the wide application of hydrogen energy. Rare earth-based hydrogen storage alloys are promising hydrogen storage medium and have been widely used as anode materials for commercial Ni/MH batteries because of the excellent hydrogen storage and electrochemical properties. In this paper, the research progress of AB5 and R-Mg-Ni-based rare earth-based hydrogen storage alloys is described in detail. The alloy composition, preparation process, heat treatment and surface treatment process have significant influence on the comprehensive properties of rare earth-based hydrogen storage alloys. The effects of element substitution on the hydrogen storage capacity, corrosion resistance, oxidation resistance and electrochemical properties of the alloys are emphasized. This paper provides a guidance and a theoretical basis for the development and application of rare earth-based hydrogen storage materials.

Abstract: This paper presents the results of performance evaluation of anode-supported solid oxide fuel cells (SOFC) with magnetron sputtered YSZ/CGO bilayer electrolyte, and composite LSCF-CGO cathode. Deposition of the YSZ/CGO electrolyte with the thickness of up to 14 microns was performed on the commercial anode substrates with dimensions of 5×5 cm². The LSCF-CGO cathode of the fuel cells was formed by the screen-printing method. The microstructure of the YSZ/CGO bilayer electrolyte and LSCF-CGO cathode was studied by scanning electron microscopy. Comparison of the fuel cells performance with different thicknesses of the YSZ and CGO layers was carried out by measuring current-voltage and power characteristics, and also by testing the long-term stability of cell power at the temperature of 750 °C and voltage of 0.7 V.

Abstract: This paper presents the analysis and design of a dual active bridge DC-DC converter for fuel cell applications. The zero voltage switching operating condition of such converter is analyzed to select an appropriate turn ratio of the high frequency transformer for a high efficiency operation. The ratio between the output voltage to the fuel cell voltage should be close to the transformer turn ratio to guarantee the zero voltage switching regimes at a light load. The prototype converter was designed to be suitable for the input voltage of 40 to 65 V and output voltage of 360 to 400 V with the transformer turn ratio of 7.33. The converter was tested with a 48 V DC power supply and with a polymer electrolyte membrane fuel cell stack. The maximum power of 700 W was delivered and the efficiency was better than 94% for the whole load range.

Abstract: This paper illustrates the results of comparative study regarding two RES storage solutions for a energen hybrid system that power supply a passive house. In this case-study was used sun and wind as a primary sources and their storage was realized in S₁ scenario through electrolytic hydrogen and in S₂ scenario through battery. The aim of this research was to demonstrate the capability of hydrogen to integrate renewable energy sources in green electricity production for stationary applications, especially to new concepts of low energy buildings. As main results was found that on S₁ is harnessed 77% of total energy production of the system to obtain hydrogen and on S₂ just 10%. Storage by electrolytic hydrogen generates 55% reduced amounts of CO₂ emissions compared with storage by battery. Total S₁ NPC was with 45,6 % higher than S₂ due to conversion equipment of hydrogen into electricity.

Abstract: Hydrogen energy is a kind of important clean energy. PEMFC(Proton exchange membrane hydrogen fuel cell) is a kind of effective hydrogen energy utilization device. It has many advantages, such as simpler structure, lower energy consumption, high reliability, quick start and easy for controlling. For the air-cooled type hydrogen fuel cell, temperature and humidity inside the PEMFC are the main factors. According to the 150W small power air-cooling type hydrogen fuel cell, the paper presented an improved purging control algorithm based on the fuzzy control. Through the dynamic adaptive control of exhaust gas purge, the PEMFC can work efficiently in the appropriate humidity conditions. The experiment results show that compared with the traditional timing purging, the proposed algorithm can effectively improve the work efficiency of the PEMFC, and reduce the hydrogen consumption

Abstract: This paper introduces the advantage of hydrogen energy source and the state of recover. It given the Thermodynamic parameter of the shift reaction of water gas into the converter waste gas contain CO(g) of high quality, and the specification of the catalysis using the smoke of the converter waste gas (Fe₃O₄). The paper states the principle and the process of separating out H₂ from the mixture gas (H₂+CO₂) by the pressure swing adsorption method (PSA).

Abstract: Development of efficient photoanodes for water splitting under solar light is desirable to surmount the possible fuel crisis in future. Ferrite systems, with their excellent visible light absorption capability, stability, non-toxicity, cost-effectiveness and abundance, are being preferred to titanates, niobates and sulfides. The present work briefly reviews the modified form of ferrites. Additionally, ZnFe₂O₄ an n-type semiconductor with the low band gap (~1.9eV) has been considered as special case of visible light PEC application. The work further emphasizes on the utilization of solution processed techniques to develop the ferrite photoanodes. The tuning of photoanode properties by virtue of electrode fabrication parameters say deposition parameters viz., precursor concentration, pH, stoichiometry has been reviewed and discussed.

Abstract: In this paper; technological challenges and commercialization barriers for Proton Exchange Membrane (PEM) fuel cell are presented. Initially, the criteria that must be met by the energy source of the future is presented from the point of view of the authors. Sustainability, high energy content and combustion independence are recognized as the main decisive factor of future fuels, which are all met by hydrogen, consequently the application of fuel cells as combustion free direct energy converters of the future. Fuel cell technology as an alternative to heat engines is discussed in the context of the current status of fuel cells in various applications. Finally, the challenges facing fuel cell technology to replace heat engines from the commercial and research points of view are presented and discussed supported by current trends in the industry. It is concluded that there have been several advancements and breakthrough in materials, manufacturing and fabricating techniques of fuel cells since the eighties, many of these challenges which are associated with cost and durability still exist when compared with the already matured technology of internal combustion engines. Any effort to achieve these goals would be a significant contribution to the technology of the fuel cell.

Abstract: Ferrites have been predicted to be potential material for photo catalytic and photo electrochemical (PEC) hydrogen generation under visible light photons. The article briefly reviews, as well as compares the supremacy of ferrites over titanates and sulfides with respect to their photo-electro catalytic hydrogen producing ability. It shows that though the band energetic of a material plays a vital role to induce the photo-splitting of water; but its optical structure, at the first instance is very important to utilize it to absorb the visible light photons. Among all the PEC materials, the low-band gap ferrites (Fe-d orbital) favor absorption of visible light photons; at the same time offer an advantage of being an eco-friendly material system. A specific focus is given to the single phase, nanostructure and composite forms of typical ZnFe₂O₄ system. Though a concise report, but also throws light on the importance and tunability of PEC properties.

Abstract: This article presents a comparative study on the synthesis and characterization of the binary and ternary ferrites for photocatalytic and photoelectrochemical applications. The importance and role of ferrite photocatalysts is discussed in context to the visible-light active photocatalyst application viz. for hydrogen production via. water-splitting. It also demonstrates that computational-exploration of any material system is key to identify, and achieve visible-light active photocatalysts.