Impact of the current fluctuation on the efficiency of Alkaline Water Electrolysis

Dobó, Zsolt; Palotás, Árpád Bence

doi:10.1016/j.ijhydene.2016.11.142

Cited by 76 publications

(36 citation statements)

References 44 publications

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“…In general, thyristor-based power supplies tend to deliver a higher degree of fluctuation, and transistor-based systems output a smoother signal. Additionally, a higher ripple frequency does not affect the system performance as much as the occurrence of low-frequency ripples [68]. Furthermore, a coherence between the ripple behavior of a power supply and the product gas quality of alkaline water electrolysis can be observed [69].…”

Section: Peripherymentioning

confidence: 98%

Alkaline Water Electrolysis Powered by Renewable Energy: A Review

2020

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Alkaline water electrolysis is a key technology for large-scale hydrogen production powered by renewable energy. As conventional electrolyzers are designed for operation at fixed process conditions, the implementation of fluctuating and highly intermittent renewable energy is challenging. This contribution shows the recent state of system descriptions for alkaline water electrolysis and renewable energies, such as solar and wind power. Each component of a hydrogen energy system needs to be optimized to increase the operation time and system efficiency. Only in this way can hydrogen produced by electrolysis processes be competitive with the conventional path based on fossil energy sources. Conventional alkaline water electrolyzers show a limited part-load range due to an increased gas impurity at low power availability. As explosive mixtures of hydrogen and oxygen must be prevented, a safety shutdown is performed when reaching specific gas contamination. Furthermore, the cell voltage should be optimized to maintain a high efficiency. While photovoltaic panels can be directly coupled to alkaline water electrolyzers, wind turbines require suitable converters with additional losses. By combining alkaline water electrolysis with hydrogen storage tanks and fuel cells, power grid stabilization can be performed. As a consequence, the conventional spinning reserve can be reduced, which additionally lowers the carbon dioxide emissions.

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Section: Peripherymentioning

confidence: 98%

Alkaline Water Electrolysis Powered by Renewable Energy: A Review

2020

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“…22 In other studies, the impact of the fluctuating current (sinusoidal, triangular, and square waveforms) and voltage (sinusoidal) sources on the water splitting efficiency (H 2 yield) were investigated, however the durability issue was not discussed. 26,27 In the development of polymer electrolyte fuel cell systems, ADT test protocols are proposed as standard potential step cycles for load fluctuation and standard potential sweep cycles for start and stop operation of vehicles for a free-volume electrochemical cell and a laboratory scale fuel cell recommended by the Fuel Cell Commercialization Conference of Japan (FCCJ) and the United States Department of Energy (DOE). These protocols are shared in industry and have contributed to new material developments.…”

Section: Introductionmentioning

confidence: 99%

A New Accelerated Durability Test Protocol for Water Oxidation Electrocatalysts of Renewable Energy Powered Alkaline Water Electrolyzers

Haleem

Kuroda

Nishiki³

et al. 2021

Electrochemistry

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For electrocatalysts of oxygen evolution reaction (OER), a new accelerated durability test (ADT) protocol is presented. The protocol is designed to closely mimic the fluctuations of renewable energies. The unit cycle of the current ADT protocol represents the "ON / OFF" operation mode. In the "ON" step, the electrolyzer operates under a DC current of 0.6 A cm-2. In the "OFF" step, the electrocatalyst is subjected to a constant potential that is clearly more cathodic than its OER onset potential (namely, 0.3, 0.5, and 0.7 V vs. RHE) for 10 or 60 s. The transition from the "ON" state to the "OFF" state occurs through a cathodic linear sweep voltammetry of a fast sweep rate to mimic the sudden changes in the renewable power. A NiCoO x /Ni-mesh electrode was used as a case study. The electrode showed remarkable durability under continuous operation (i = 0.6 A cm-2) for about 900 hours. However, it did suffer severe degradation after a certain number of ADT cycles, and the rate of degradation mainly depends on the potential value and the duration of the "OFF" step. Interestingly, the inclusion of the 10-sec open-circuit potential step after the "ON" step clearly mitigates the impact of energy fluctuations on the durability of OER electrocatalysts.

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“…The comparison was conducted by analyzing the resulting specific energy consumptions for a 5 kW alkaline water electrolyzer. A labscale alkaline water electrolyzer was analyzed in [21], where steady DC current resulted in minimized cell efficiency loss.…”

Section: Introductionmentioning

confidence: 99%

Effect of Converter Topology on the Specific Energy Consumption of Alkaline Water Electrolyzers

Koponen

Ruuskanen

Kosonen

et al. 2019

IEEE Trans. Power Electron.

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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 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 A 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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Impact of the current fluctuation on the efficiency of Alkaline Water Electrolysis

Cited by 76 publications

References 44 publications

Alkaline Water Electrolysis Powered by Renewable Energy: A Review

Alkaline Water Electrolysis Powered by Renewable Energy: A Review

A New Accelerated Durability Test Protocol for Water Oxidation Electrocatalysts of Renewable Energy Powered Alkaline Water Electrolyzers

Effect of Converter Topology on the Specific Energy Consumption of Alkaline Water Electrolyzers

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