The Experts below are selected from a list of 15873 Experts worldwide ranked by ideXlab platform
Karl Johann Jakob Mayrhofer - One of the best experts on this subject based on the ideXlab platform.
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an alkaline water Electrolyzer with nickel electrodes enables efficient high current density operation
International Journal of Hydrogen Energy, 2018Co-Authors: Maximilian Schalenbach, Olga Kasian, Karl Johann Jakob MayrhoferAbstract:Abstract Low-temperature industrial water electrolysis is typically conducted using either liquid alkaline electrolytes or acidic polymer electrolyte membranes (PEMs). The latter approach is considered to be more efficient but also more expensive as it requires Pt and Ir based catalysts. This study reports on an alkaline water Electrolyzer with Ni electrodes that operates at a current density of 2 A/cm2 with a cell voltage of 1.85 V, which provides a comparable voltage-current characteristic to the state-of-the-art PEM water Electrolyzers. Thin Ni mesh electrodes with surface areas that are thousand times higher than the geometric area were manufactured by an easily scalable and cheap process, i.e. metallurgical hot dip galvanization with subsequent de-alloying. With a thin porous polymer of approximately 140 μm as the diaphragm a low cell resistance of 0.11 Ω cm−2 was obtained.
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importance and challenges of electrochemical in situ liquid cell electron microscopy for energy conversion research
Accounts of Chemical Research, 2016Co-Authors: Nejc Hodnik, Karl Johann Jakob Mayrhofer, Gerhard DehmAbstract:ConspectusThe foreseeable worldwide energy and environmental challenges demand renewable alternative sources, energy conversion, and storage technologies. Therefore, electrochemical energy conversion devices like fuel cells, electrolyzes, and supercapacitors along with photoelectrochemical devices and batteries have high potential to become increasingly important in the near future. Catalytic performance in electrochemical energy conversion results from the tailored properties of complex nanometer-sized metal and metal oxide particles, as well as support nanostructures. Exposed facets, surface defects, and other structural and compositional features of the catalyst nanoparticles affect the electrocatalytic performance to varying degrees. The characterization of the nanometer-size and atomic regime of electrocatalysts and its evolution over time are therefore paramount for an improved understanding and significant optimization of such important technologies like Electrolyzers or fuel cells. Transmission el...
Nelson A Kelly - One of the best experts on this subject based on the ideXlab platform.
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optimization of solar powered hydrogen production using photovoltaic electrolysis devices
International Journal of Hydrogen Energy, 2008Co-Authors: Thomas L Gibson, Nelson A KellyAbstract:Abstract Hydrogen fuel for fuel cell vehicles can be produced by using solar electric energy from photovoltaic (PV) modules for the electrolysis of water without emitting carbon dioxide or requiring fossil fuels. In the past, this renewable means of hydrogen production has suffered from low efficiency (2–6%), which increased the area of the PV array required and therefore, the cost of generating hydrogen. In this research, the efficiency of the PV-electrolysis system was optimized by matching the voltage and maximum power output of the photovoltaics to the operating voltage of proton exchange membrane (PEM) Electrolyzers. The optimization process increased the hydrogen generation efficiency to 12% for a solar powered PV-PEM Electrolyzer that could supply enough hydrogen to operate a fuel cell vehicle.
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a solar powered high efficiency hydrogen fueling system using high pressure electrolysis of water design and initial results
International Journal of Hydrogen Energy, 2008Co-Authors: Nelson A Kelly, Thomas L Gibson, David B OuwerkerkAbstract:Abstract Hydrogen for fuel-cell electric vehicles (FCEVs) was produced using clean, renewable solar energy to electrolyze water. This report describes the design, construction, and initial performance testing of a solar hydrogen fueler at the GM Proving Ground in Milford, MI. The system used high-efficiency photovoltaic (PV) modules, a high-pressure (6500 psi, 44.8 MPa) Electrolyzer, and an optimized direct connection between the PV and Electrolyzer systems. This resulted in world-class solar to hydrogen efficiencies as high as 9.3% (based on H2 lower heating value, LHV). The system could potentially supply approximately 0.5 kg of hydrogen per day from solar power for the average solar insolation in Detroit; more hydrogen would be produced in locations with more abundant sunshine. This is sufficient hydrogen to operate an FCEV for an average daily urban commute. Thus, the solar hydrogen fueler testing served as a “proof of concept” for clean, renewable hydrogen with potential applications including convenient, clean, quiet, small-scale home fueling of FCEVs (that can contribute to the growth of a future FCEV fleet) and fueling in remote locations where grid electricity is not available.
R Durand - One of the best experts on this subject based on the ideXlab platform.
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design and performance of a solid polymer electrolyte water Electrolyzer
International Journal of Hydrogen Energy, 1996Co-Authors: P Millet, F Andolfatto, R DurandAbstract:Abstract The development of medium size solid polymer electrolyte (SPE) water Electrolyzers is of great practical interest for on-board production of oxygen in submarines and for energy storage purposes in space applications. While the SPE technology has largely demonstrated its potential on the laboratory scale, very little information is available in the literature on the technological characteristics and electrochemical performances of larger water Electrolyzers. In this paper, we present part of the experience that we gained in the development of medium size electrolysis units. A 0.5 kW SPE water Electrolyzer was designed and tested. Its performance is discussed with respect to technological design (fluids and current distribution) and operating conditions.
Michihisa Koyama - One of the best experts on this subject based on the ideXlab platform.
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battery assisted low cost hydrogen production from solar energy rational target setting for future technology systems
International Journal of Hydrogen Energy, 2019Co-Authors: Yasunori Kikuchi, Takayuki Ichikawa, Masakazu Sugiyama, Michihisa KoyamaAbstract:Abstract The massive implementation of renewable energy requires sophisticated assessments considering the combination of feasible technology options. In this study, a techno-economic analysis was conducted for hydrogen production from photovoltaic power generation (PV) utilizing a battery-assisted Electrolyzer. The installed capacity of each component technology was optimized for the wide range of unit costs of electricity from the PV, battery, and proton-exchange membrane Electrolyzer. Leveling of PV output by battery, the necessary capacity of Electrolyzer is suppressed and the operating ratio of Electrolyzer increases. The battery-assist will result in a lower hydrogen production cost when the benefit associated with the smaller capacity and higher operation ratio of the Electrolyzer exceeds the necessary investment for battery installation. The results from this study indicated the cost of hydrogen as low as 17 to 27 JPY/Nm3 using a combination of technologies and the achievement of ambitious individual cost targets for batteries, PV, and Electrolyzers.
Jero Ahola - One of the best experts on this subject based on the ideXlab platform.
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Effect of Converter Topology on the Specific Energy Consumption of Alkaline Water Electrolyzers
IEEE Transactions on Power Electronics, 2019Co-Authors: Joonas Koponen, Vesa Ruuskanen, Antti Kosonen, Markku Niemelä, Jero AholaAbstract:Water electrolysis will be used to produce renewable hydrogen for energy storage and Power-to-X applications in the future renewable-energy-based energy systems. Therefore, the energy efficiency of hydrogen production will probably become a major issue. In this study, the effect of practical supply power converters on the specific energy consumption of megawatt (MW)-scale alkaline Electrolyzers is studied and compared with an ideal dc power supply. The current quality and the stack specific energy consumption are studied in the case of traditional thyristor rectifiers and a transistor-based converter. The stack specific energy consumption is analyzed based on the simulated current waveforms and the electrical equivalent circuit of the Electrolyzer stack. It is found that the transistor-based converter offers up to 14% lower Electrolyzer stack specific energy consumption than the 6-pulse thyristor rectifier and up to 9.2% lower Electrolyzer stack specific energy consumption than the 12-pulse thyristor rectifier as the current varies between 5000 and 1000 A. The simulated change in the stack specific energy consumption of the MW-scale alkaline water Electrolyzer outweighs the losses occurring in the rectifiers. Further, selection of the ac voltage level may have a more adverse effect on the stack specific energy consumption with the thyristor rectifier topologies compared with the transistor-based topologies.
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Dynamic Behavior Emulation of Alkaline Electrolyzer by Power-Hardware-in - the- Loop
2018 20th European Conference on Power Electronics and Applications (EPE'18 ECCE Europe), 2018Co-Authors: Antti Kosonen, Vesa Ruuskanen, Joonas Koponen, Markku Niemelä, Jero Ahola, Jorn Geisbusch, Philip KreideweisAbstract:Hydrogen production is energy intensive, and hence, the efficiency of the process is essential. Power electronics play an important role in energy efficiency of water Electrolyzers. In general, the research requires real devices and handling of hydrogen. On the other hand, the water Electrolyzer stack can be replaced by a power hardware-in-the-loop (PHIL) emulator that includes the same electrical characteristics as the real one. However, water Electrolyzers are dynamic devices, and hence, the PHIL emulator should be able to realize the same bandwidth. Dynamics are important when studying DC power quality effects on water Electrolyzers. The switching phenomena that can be seen after the utilized rectification are up to several kHz in frequency. This paper examines a dynamic PHIL test system for the purpose of emulation of water Electrolyzers.
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PEM water Electrolyzer model for a power-hardware-in-loop simulator
International Journal of Hydrogen Energy, 2017Co-Authors: Vesa Ruuskanen, Joonas Koponen, Antti Kosonen, Markku Niemelä, Kimmo Huoman, Jero AholaAbstract:Abstract Power-electronics-based power-hardware-in-loop (PHIL) simulator for water Electrolyzer emulation with a nominal current of 405 A is developed to study the Electrolyzer as part of a smart grid and to analyze the characteristics of various Electrolyzer power supply electronics. A simplified model of a proton exchange membrane (PEM) Electrolyzer is implemented into the PHIL simulator to describe the voltage and current characteristics of the Electrolyzer stack. The model is verified comparing the current and the estimated hydrogen production of the PHIL simulator with the measured values of the commercial PEM Electrolyzer following the measured solar photovoltaic (PV) system output power.
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Considering the power quality in the fower-hardware-ln-loop simulation of the water Electrolyzers
2017 19th European Conference on Power Electronics and Applications (EPE'17 ECCE Europe), 2017Co-Authors: Vesa Ruuskanen, Joonas Koponen, Teemu Sillanpää, Antti Kosonen, Markku Niemelä, Jero AholaAbstract:Considering the effect of current and voltage frequency content in the power-hardware-in-loop (PHIL) simulation of water Electrolyzers is studied as the AC components may cause additional losses in the Electrolyzer stack. A transistor based power supply is used to excite DC current with selected AC components for an alkaline Electrolyzer and a PHIL simulator. The practical current and voltage waveforms are analyzed, and the possibilities to take the power quality aspects in consideration in the PHIL simulation is discussed.