The Experts below are selected from a list of 1428 Experts worldwide ranked by ideXlab platform

V N Fateev - One of the best experts on this subject based on the ideXlab platform.

  • evaluation of carbon supported pt and pd nanoparticles for the hydrogen evolution reaction in pem water Electrolysers
    Journal of Power Sources, 2008
    Co-Authors: S A Grigoriev, P Millet, V N Fateev
    Abstract:

    Carbon-supported Pt and Pd nanoparticles (CSNs) were synthesized and electrochemically characterized in view of potential application in proton exchange membrane (PEM) water Electrolysers. Electroactive metallic nanoparticles were obtained by chemical reduction of precursor salts adsorbed to the surface of Vulcan XC-72 carbon carrier, using ethylene glycol as initial reductant and with final addition of formaldehyde. CSNs were then coated over the surface of electron-conducting working electrodes using an alcoholic solution of perfluorinated polymer. Their electrocatalytic activities with regard to the hydrogen evolution reaction (HER) were measured in sulfuric acid solution using cyclic voltammetry, and in a PEM cell during water electrolysis. Results obtained show that palladium can be advantageously used as an alternative electrocatalyst to platinum for the HER in PEM water Electrolysers. Developed electrocatalysts could also be used in PEM fuel cells.

  • pure hydrogen production by pem electrolysis for hydrogen energy
    International Journal of Hydrogen Energy, 2006
    Co-Authors: S A Grigoriev, V I Porembsky, V N Fateev
    Abstract:

    Last years hydrogen as energy carrier becomes one of the best solutions of energy and ecological problems. Intensive development of fuel cells, especially based on proton exchange membrane (PEM), where pure hydrogen is needed, stimulates electrolyzers development for the future application in hydrogen energy and technology. From point of view of the authors PEM electrolysis is very perspective for this goal. Advantages and possible fields of applications of this type of electrolyzers in comparison with another one are reviewed. Some results achieved up to now in PEM electrolysis, including last achievement of the authors, are summarized.

Gareth Hinds - One of the best experts on this subject based on the ideXlab platform.

  • in situ characterisation of pem water Electrolysers using a novel reference electrode
    Electrochemistry Communications, 2015
    Co-Authors: E Brightman, James Dodwell, Nick Van Dijk, Gareth Hinds
    Abstract:

    Polymer electrolyte membrane water Electrolysers (PEMWEs) are a promising technology for hydrogen production but catalyst degradation mechanisms are poorly understood, hampering informed catalyst design for extended lifetimes and the use of more economical loadings. Here we demonstrate the application of an innovative reference electrode to the study of catalyst degradation in an operating PEMWE. This approach enables separation of the relative contribution of anode and cathode to the overall water splitting reaction. It is shown that, in shut-down periods during power cycling, the cathode contributes more to changes in open circuit voltage than the anode. Changes in the electrochemical surface area of the platinum cathode as a result of power cycling are measured in situ for the first time using hydrogen underpotential cyclic voltammetry. The results demonstrate that degradation of the platinum cathode plays a more significant role than conventionally assumed by the electrolyser community, which has tended to focus more on the iridium/ruthenium oxide anode because it dominates the performance of the cell.

  • in situ characterisation of pem water Electrolysers using a novel reference electrode
    Electrochemistry Communications, 2015
    Co-Authors: E Brightman, James Dodwell, Nick Van Dijk, Gareth Hinds
    Abstract:

    Polymer electrolyte membrane water Electrolysers (PEMWEs) are a promising technology for hydrogen production but catalyst degradation mechanisms are poorly understood, hampering informed catalyst design for extended lifetimes and the use of more economical loadings. Here we demonstrate the application of an innovative reference electrode to the study of catalyst degradation in an operating PEMWE. This approach enables separation of the relative contribution of anode and cathode to the overall water splitting reaction. It is shown that, in shut-down periods during power cycling, the cathode contributes more to changes in open circuit voltage than the anode. Changes in the electrochemical surface area of the platinum cathode as a result of power cycling are measured in situ for the first time using hydrogen underpotential cyclic voltammetry. The results demonstrate that degradation of the platinum cathode plays a more significant role than conventionally assumed by the electrolyser community, which has tended to focus more on the iridium/ruthenium oxide anode because it dominates the performance of the cell.

Mahdi Kiaee - One of the best experts on this subject based on the ideXlab platform.

  • Utilisation of alkaline Electrolysers in existing distribution networks to increase the amount of integrated wind capacity
    Journal of Energy Storage, 2018
    Co-Authors: Mahdi Kiaee, David G. Infield, Andrew Cruden
    Abstract:

    Hydrogen could become a significant fuel in the future especially within the transportation sector. Alkaline Electrolysers supplied with power from renewable energy sources could be utilised to provide carbon free hydrogen for future hydrogen filling stations supplying Hydrogen Fuel Cell Vehicles (HFCV), or Internal Combustion Engines (ICEs) modified to burn hydrogen. However, there is a need to develop and use appropriate strategies such that the technology delivers greater economic and environmental benefits. In this work, the use of alkaline Electrolysers to increase the capacity of integrated wind power in existing radial distribution networks is explored. A novel optimisation approach for sizing, placement and controlling Electrolysers has been introduced, and its performance is assessed through modelling using a United Kingdom Generic Distribution System (UKGDS) case study. The controller objective is to dispatch alkaline Electrolysers appropriately to maximise the total amount of profit from selling hydrogen and reduce the losses within the network while considering the realistic characteristics of pressurised alkaline electrolysis plants and satisfying the power system constraints. The impacts of increasing wind power capacity or the initial size of hydrogen filling stations on the results have been investigated and discussed.

  • Utilisation of alkaline Electrolysers to improve power system frequency stability with a high penetration of wind power
    IET Renewable Power Generation, 2014
    Co-Authors: P Chladek, David G. Infield, Andrew Cruden, Mahdi Kiaee
    Abstract:

    Controlling the frequency of power systems with high wind power penetration is more difficult due to the high variability of the wind power. One possible mainstream energy carrier in the future, particularly for the transportation sector, is Hydrogen, and water electrolysis is one of the most attractive ways to produce it. In this study, a detailed model of a steam turbine generator has been produced in MATLAB Simulink and used to investigate a scenario in which there is a 25% penetration of wind power. To improve the frequency stability of the power system, large scale alkaline Electrolysers used in future Hydrogen filling stations could adjust their load with respect to the frequency deviation from nominal and can significantly reduce fluctuations in system frequency. For the case examined, five times less spinning reserve is required in order to maintain the power system frequency within operational limits when Electrolysers are utilised as a form of demand side management (DSM), compared to the base case where no electrolyser DSM plant is available. Actual operational data from a pressurised alkaline electrolyser is used to evidence the fast load changing capability of such Electrolysers.

  • development of new materials for alkaline Electrolysers and investigation of the potential electrolysis impact on the electrical grid
    Renewable Energy, 2013
    Co-Authors: Andrew Crude, Mahdi Kiaee, Tamunosaki Graham Douglas, David Infield, Amitava Roy
    Abstract:

    This paper discusses development of new materials for alkaline Electrolysers and assesses the impact of large penetrations of electrolysis plants on the electrical grid.

  • Demand side management using alkaline Electrolysers within the UKGDS simulation network
    CIRED 2011 21st International Conference on Electricity Distribution, 2011
    Co-Authors: Mahdi Kiaee, Andrew Cruden, David G. Infield
    Abstract:

    Due to the problem of pollution from fossil fuels, there has been an effort to diversify our energy supply especially in the transportation sector and to use cleaner fuels. The interest in a hydrogen energy economy has been increasing recently. One of the Hydrogen production methods is to use an electrolyser. Hydrogen can help the transition from energy infrastructure available today into an energy world with a growing renewable electricity supply. As the number of time varying renewable power generators increases in the electrical power system, the usage of demand side management tools will become more important. Electrolysers could be used as a significant new demand side management tool in these networks to improve the quality of their operation. The UKGDS High Voltage Underground Network has been modelled with Electrolysers and wind farms added to four different buses to investigate the impact of Electrolysers on this network. The Electrolysers are assumed to be able to consume variable power (within their maximum and minimum limits) from the network. The impact of adding Electrolysers on the network voltages and transmission losses has been investigated through modelling. Despite the fact that Electrolysers behave like additional load on the system, the transmission losses were decreased by 2.91% while the Electrolysers were added to the electrical grid. This reduction in transmission loss is achieved as a result of the proper selection of the location and size of Electrolysers with respect to the location and size of the wind farms and also the control strategy which is used to run the Electrolysers with respect to the power output from the wind farms.

  • the impact on the electrical grid of hydrogen production from alkaline Electrolysers
    International Universities Power Engineering Conference, 2010
    Co-Authors: Mahdi Kiaee, David G. Infield, Andrew Crude, Tamunosaki Graham Douglas
    Abstract:

    In the next 50 years, it is possible that hydrogen could become widely used as a fuel for transport. The result of this change could increase energy security and reduce environmental impacts, such as CO 2 emissions. Hydrogen produced by Electrolysers could be used in Fuel Cell Vehicles (FCVs) with no direct harmful emission. In this research a scenario involving the widespread availability of Hydrogen at UK fuel stations for the purpose of supplying all vehicles is investigated. Calculations have been carried out to find out how much Hydrogen is needed for road transportation in the UK to be met in this way. The Electrolysers will be assumed to be able to follow supply, i.e. their electricity consumption can be adjusted to follow changes in renewable energy generation in the power system. In this way these new electrolyser loads can be used for demand side management, facilitating the introduction of high volumes of renewable energy generation (mainly wind energy) to the power system. The interaction between the Electrolysers and the network is investigated through modelling using MATLAB software.

Elton J G Santos - One of the best experts on this subject based on the ideXlab platform.

  • ultrahigh current density niobium disulfide catalysts for hydrogen evolution
    Nature Materials, 2019
    Co-Authors: Jieun Yang, Abdul Rahman Mohmad, Yan Wang, Raymond Fullon, Xiuju Song, Fang Zhao, Ibrahim Bozkurt, Mathias Augustin, Elton J G Santos
    Abstract:

    Metallic transition metal dichalcogenides (TMDs)1–8 are good catalysts for the hydrogen evolution reaction (HER). The overpotential and Tafel slope values of metallic phases and edges9 of two-dimensional (2D) TMDs approach those of Pt. However, the overall current density of 2D TMD catalysts remains orders of magnitude lower (~10–100 mA cm−2) than industrial Pt and Ir Electrolysers (>1,000 mA cm−2)10,11. Here, we report the synthesis of the metallic 2H phase of niobium disulfide with additional niobium (2H Nb1+xS2, where x is ~0.35)12 as a HER catalyst with current densities of >5,000 mA cm−2 at ~420 mV versus a reversible hydrogen electrode. We find the exchange current density at 0 V for 2H Nb1.35S2 to be ~0.8 mA cm−2, corresponding to a turnover frequency of ~0.2 s−1. We demonstrate an electrolyser based on a 2H Nb1+xS2 cathode that can generate current densities of 1,000 mA cm−2. Our theoretical results reveal that 2H Nb1+xS2 with Nb-terminated surface has free energy for hydrogen adsorption that is close to thermoneutral, facilitating HER. Therefore, 2H Nb1+xS2 could be a viable catalyst for practical Electrolysers. Metallic transition metal dichalcogenides are promising catalysts for hydrogen evolution reactions but their performances are still lower than industrial Pt and Ir Electrolysers. The metallic 2H phase of niobium disulfide now exhibits enhanced current densities versus a reversible hydrogen electrode.

Pablo Sanchis - One of the best experts on this subject based on the ideXlab platform.

  • integration of commercial alkaline water Electrolysers with renewable energies limitations and improvements
    International Journal of Hydrogen Energy, 2016
    Co-Authors: Alfredo Ursua, Ernesto L Arrios, Julio Pascual, Idoia Sa Marti, Pablo Sanchis
    Abstract:

    Abstract Hydrogen can be stored, transported and used in a large number of applications in which fossil fuels are currently used. From a sustainable point of view, the synergy existing between hydrogen and renewable energy sources shows great potential. In this respect, hydrogen can be produced from water electrolysis using the electricity generated by renewable systems. This paper studies the integration of a 1 Nm3 h−1 alkaline water electrolyser with photovoltaic solar energy (PVE) and wind energy (WE) in a stand-alone system. In particular, a one year energy balance of the conventional integration of the electrolyser with PVE and WE is carried out. To do so, actual weather data are used for irradiance, ambient temperature and wind speed, in addition to the technical specifications and characteristics of a 6.8 kWp PV generator and a 6 kW wind turbine. This energy evaluation reveals the main limitations of commercial Electrolysers, such as the lower operating limit and the number of stops permitted by manufacturers. Two strategies are therefore proposed to improve the integration of conventional Electrolysers, namely to allow the electrolyser to operate for a period of 10 min under the lower operating limit and to integrate a battery bank. Both strategies achieve successful results, with a reduction in the number of stops by up to 62.1% for the PVE integration and 63.1% for the WE, which should increase the electrolyser service life, and an increase in energy efficiency by up to 6.3% for the PVE integration and 7.6% for the WE.

  • photovoltaic hydrogen production with commercial alkaline Electrolysers
    18th World Hydrogen Energy Conference, 2010
    Co-Authors: Alfredo Ursua, Pablo Sanchis, Jesus Lopez, Detlef Stolte, E Gubia, Thomas Grube, Luis Marroyo
    Abstract:

    Renewable energy sources and Electrolysis generate the so-called green Hydrogen, a zeroemission and potentially fossil fuel independent energy source. However, the inherent variability of the renewable energy sources implies a mode of operation for which most current Electrolysers have not been designed. This paper analyses the operation of a water electrolyser fed with photovoltaic (PV) generator electric profile. The system, Integrated by a 1 Nm/h Hydrogenics alkaline electrolyser and a 5100 W PV generator with 60 BP585 modules, is installed at the Public University of Navarra (Spain). The PV generator profile fed to the electrolyser is emulated by a custom-made apparatus designed and built by the authors of this paper. The profile is designed according to real irradiance data measured by a calibration cell. The irradiance data are converted to the electric power profile that the PV generator would have delivered in case of having been connected to the electrolyser by means of a DC/DC converter with maximum power point tracking (MPPT). Finally, from previously measured power-current electrolyser characteristic curves, the current profile to be delivered to the electrolyser is obtained and programmed to the electronic device. The electrolyser was tested for two types of days. During the first day, the irradiance was very stable, whereas during the second day, the irradiance was very variable. The experimental results show an average power consumption rate and an efficiency of 4908 Wh/Nm and 72.1%, on the first day, and 4842 Wh/Nm and 73.3% on the second day. The electrolyser performance was particularly good in spite of the high variability of the electric supply of the second day.

  • influence of the power supply on the energy efficiency of an alkaline water electrolyser
    International Journal of Hydrogen Energy, 2009
    Co-Authors: Alfredo Ursua, E Gubia, Luis Marroyo, L M Gandia, P M Dieguez, Pablo Sanchis
    Abstract:

    Abstract Electric energy consumption represents the greatest part of the cost of the hydrogen produced by water electrolysis. An effort is being carried out to reduce this electric consumption and improve the global efficiency of commercial Electrolysers. Whereas relevant progresses are being achieved in cell stack configurations and electrodes performance, there are practically no studies on the effect of the electric power supply topology on the electrolyser energy efficiency. This paper presents an analysis on the energy consumption and efficiency of a 1 N m3 h−1 commercial alkaline water electrolyser and their dependence on the power supply topology. The different topologies of power supplies are first summarised, analysed and classified into two groups: thyristor-based (ThPS) and transistor-based power supplies (TrPS). An Electrolyser Power Supply Emulator (EPSE) is then designed, developed and satisfactorily validated by means of simulation and experimental tests. With the EPSE, the electrolyser is characterised both obtaining its I–V curves for different temperatures and measuring the useful hydrogen production. The electrolyser is then supplied by means of two different emulated electric profiles that are characteristic of typical ThPS and TrPS. Results show that the cell stack energy consumption is up to 495 W h N m−3 lower when it is supplied by the TrPS, which means 10% greater in terms of efficiency.