Experimental study on laboratory scale Totalized Hydrogen Energy Utilization System using wind power data

The renewable energy source like wind energy generates electric power with intermittent nature. Hydrogen energy system can help to solve the fluctuation problem of the wind power. Totalized Hydrogen Energy Utilization System (THEUS) consists of a Unitized Reversible Fuel Cell (URFC), a hydrogen storage tank, and other auxiliary components. Wind power is inherently variable; the URFC will be subjected to a dynamic input power profile in water electrolyzer mode operation. This paper describes the THEUS operation and performance at different variations in intermittent wind power. The performance of the THEUS was evaluated in water electrolyzer and fuel cell mode operation. The stack efficiency, system efficiency, and system efficiency including heat output from the URFC were presented at each operation. The total efficiency of the URFC and THEUS were also investigated. The maximum total efficiency of the URFC and THEUS were 53% and 66%, respectively.     

Towards a hydrogen economy in Romania: Statistics,technical and scientific general aspects

The present work features an analysis of the current state of Romania's current policy in the context of hydrogen economy. The possibilities and limitations concerning the transition towards the hydrogen economy in Romania are discussed taking into account a number of aspects, including: the degree of development of the electric power infrastructure, aspects from petrochemical and agrochemical industry, transport infrastructure, socioeconomic development indicators, activity and dynamics of the scientific community and attitude of central authorities. All these are important aspects that contribute to technology deployment. The article presents both advantages and disadvantages from Romania, provides concrete examples, gives information, makes comparisons and provides recommendations, taking into account national aspects. Key areas of promise for hydrogen technologies in Romania are identified. The paper concludes with recommendations for actions in order to begin the process of transition towards a hydrogen economy.     

Fuel cells: Optimism gone – Hard work still there

A brief overview of the progress in fuel cell applications and basic technology development is presented, as a backdrop for discussing readiness for penetration into the marketplace as a solution to problems of depletion, safety, climate or environmental impact from currently used fossil and nuclear fuel-based energy technologies.     

Application of CuNi–CeO2 fuel electrode in oxygen electrode supported reversible solid oxide cell

The oxygen electrode-supported reversible solid oxide cell (RSOC) has demonstrated distinguishing advantages of fuel flexibility, shorter gas diffusion path and more choices for fuel electrode materials. However, there are serious drawbacks including the difficulty of co-firing the oxygen electrode and electrolyte, and the inefficient electrochemical performance. In this study, a (La_0.8Sr_0.2)_0.95MnO_3-δ (LSM) supported RSOC with the configuration of La_0.6Sr_0.4Fe_0.9Sc_0.1O_3-δ (LSFSc)-YSZ/YSZ/CuNi–CeO₂-YSZ is fabricated by tape casting, co-sintering and impregnation technologies. The single cell is evaluated at both fuel cell (FC) and electrolysis cell (EC) mode. Significant maximum power density of 436.0 and 377 mW cm^?2 is obtained at 750 °C in H₂ and CH₄ fuel atmospheres, respectively. At electrolysis voltage of 1.3 V and 50% steam content, current density of ?0.718, ?0.397, ?0.198 and ?0.081 A cm^?2 is obtained at 750, 700, 650 and 600 °C respectively. Much higher electrolysis performance than FC mode is exhibited probably due to the optimized electrodes with increased triple phase boundary (TPB) area and faster gas diffusion (oxygen and steam) and electrochemical reactions for water splitting. Additionally, the short-term stability of single cell in H₂ and CH₄ are also studied.     

国内外氢能发展概况

在21世纪新能源中,清洁而高效的氢可能扮演重要的角色,其它各种能源都可以转化为比较容易储存的氢。我国氢源丰富,技术研发在国际上处于领先水平,应加快燃料电池汽车的市场化步伐,积极培育以储氢罐、加氢站、输氢管道等为标志的氢经济或氢产业。     

A concept of combined cooling,heating and power system utilising solar power and based on reversible solid oxide fuel cell and metal hydrides

In energy systems, multi-generation including co-generation and tri-generation has gained tremendous interest in the recent years as an effective way of waste heat recovery. Solid oxide fuel cells are efficient power plants that not only generate electricity with high energy efficiency but also produce high quality waste heat that can be further used for hot and chilled water production. In this work, we present a concept of combined cooling, heating and power (CCHP) energy system which uses solar power as a primary energy source and utilizes a reversible solid oxide fuel cell (R-SOFC) for producing hydrogen and generating electricity in the electrolyser (SOEC) and fuel cell (SOFC) modes, respectively. The system uses “high temperature” metal hydride (MH) for storage of both hydrogen and heat, as well as “low temperature” MH's for the additional heat management, including hot water supply, residential heating during winter time, or cooling/air conditioning during summer time.The work presents evaluation of energy balances of the system components, as well as heat-and-mass transfer modelling of MH beds in metal hydride hydrogen and heat storage system (MHHS; MgH₂), MH hydrogen compressor (MHHC; AB₅; A = La + Mm, BNi + Co + Al + Mn) and MH heat pump (MHHP; AB₂; A = Ti + Zr, BMn + Cr + Ni + Fe). A case study of a 3 kWe R-SOFC is analysed and discussed. The results showed that the energy efficiencies are 69.4 and 72.4% in electrolyser and fuel cell modes, respectively. The round-trip COP's of metal hydride heat management system (MHHC + MHHP) are close to 40% for both heating and cooling outputs. Moreover, the tri-generation leads to an improvement of 36% in round-trip energy efficiency as compared to that of a stand-alone R-SOFC.     

Projections of the price of hydrogen fuel

The concept of remote solar plant giving piped hydrogen fuel is gaining strength with the likelihood of realization. Electricity (in 1977 U.S. $) for use in electrolysis with a 50 per cent load factor at the producing plant would be 1 cent/kWh now, and 1.5 cents (still 1977$) in 1985. Potential will be 1.5 V. Cost of 1 MBTU will be in the region of $5 (electrolysis). Photovoltaic electricity using Fresnel concentration and heat exchangers should cost 1 cent/kWh. H₂ transport costs should be some 1 mill/1000 km. Examination of ten approaches gives a maximum hydrogen cost of $9/MBTU, a likely value of $5, and speculative laboratory possibilities which could give $1/MBTU.     

Analysis of the control strategies for fuel saving in the hydrogen fuel cell vehicles

A hydrogen fuel cell vehicle requires fuel cells, batteries, supercapacitors, controllers and smart control units with their control strategies. The controller ensures that a control strategy predicated on the data taken from the traction motor and energy storage systems is created. The smart control unit compares the fuel cell nominal output power with the vehicle power demand, calculates the parameters and continually adjusts the variables. The control strategies that can be developed for these units will enable us to overcome the technological challenges for hydrogen fuel cell vehicles in the near future. This study presents the best hydrogen fuel cell vehicle configurations and control strategies for safe, low cost and high efficiency by comparing control strategies in the literature for fuel economy.     

Development of a PrBaMn2O5+δ-La0.8Sr0.2Ga0.85Mg0.15O3-δ composite electrode by scaffold infiltration for reversible solid oxide fuel cell applications

In this study, a PrBaMn₂O_5+δ (PBMO)-La_0.8Sr_0.2Ga_0.85Mg_0.15O_3-δ (LSGM) composite catalyst was developed for use in a reversible solid oxide fuel cell (SOFC) electrode. Through a chemical compatibility test, a heat treatment temperature at which secondary phases did not form between LSGM and PBMO was determined, and a PBMO-LSGM composite electrode material was synthesized by a scaffold infiltration technique capable of synthesizing a catalyst within the appropriate temperature range. A half-cell test consisting of two identical PBMO-LSGM composite electrodes supported on LSGM pellets found that the optimum infiltration amount of PBMO with respect to the LSGM scaffold was approximately 20 wt%. Electrochemical performance measurements under reversible SOFC operating conditions on a half-cell with 19.7 wt% PBMO-LSGM composite electrodes showed a specific resistance and activation energy significantly lower than those of conventional Ni-based cermet and perovskite-type materials, indicating that the developed PBMO-LSGM composite electrode is a promising electrocatalyst for reversible SOFCs.     

Fabrication of hydrogen electrode supported cell for utilized regenerative solid oxide fuel cell application

A utilized regenerative solid oxide fuel cell (URSOFC) provides the dual function of performing energy storage and power generation, all in one unit. When functioning as an energy storage device, the URSOFC acts like a solid oxide electrolyzer cell (SOEC) in water electrolysis mode; whereby the electric energy is stored as (electrolyzied) hydrogen and oxygen gases. While hydrogen is useful as a transportation fuel and in other industrial applications, the URSOFC also acts as a solid oxide fuel cell (SOFC) in power generation mode to produce electricity when needed. The URSOFC would be a competitive technology in the upcoming hydrogen economy on the basis of its low cost, simple structure, and high efficiency. This paper reports on the design and manufacturing of its anode support cell using commercially available materials. Also reported are the resulting performance, both in electrolysis and fuel cell modes, as a function of its operating parameters such as temperature and current density. We found that the URSOFC performance improved with increasing temperature and its fuel cell mode had a better performance than its electrolysis mode due to a limited humidity inlet causing concentration polarization. In addition, there were great improvements in performance for both the SOFC and SOEC modes after the first test and could be attributed to an increase in porosity within the oxygen electrode, which was beneficial for the oxygen reaction.     

Electrochemical stability of La0.6Sr0.4Co0.2Fe0.8O3−δ-infiltrated YSZ oxygen electrode for reversible solid oxide fuel cells

La_0.6Sr_0.4Co_0.2Fe_0.8O_3−δ (LSCF)-YSZ (yttria stabilized zirconia) oxygen electrodes were developed by an infiltration process for reversible solid oxide fuel cells (RSOFCs). Electrochemical performance of the LSCF-YSZ composite oxygen electrode was investigated in both fuel cell and steam electrolysis modes. Galvanostatic polarization operated at ±600 mA cm⁻² and 750 °C showed that the cell has a voltage degradation rate of 3.4% and 4.9% for fuel cell mode and steam electrolysis mode, respectively. Post-test SEM (scanning electronic microscopy) analysis of the electrodes indicates that the agglomeration of infiltrated LSCF particles is possibly responsible for the performance degradation of the cell.