Factors influencing the performance and durability of polymer electrolyte membrane water electrolyzer: A review

Hydrogen is the best energy vector for renewable and intermittent power sources. Electrolysis coupled with renewable energy resources is the most promising for the production of green hydrogen among the current hydrogen production methods. The polymer electrolyte membrane water electrolyzer (PEMWE) is the frontrunner of electrolyzer technology because of its ability to operate at high current densities and compact design, thereby enabling high-pressure operation. This review summarizes the static parameters (stack assembly and design aspects) and dynamic parameters (operating parameters and gas bubble removal) affecting PEMWE's performance, as well as static parameters (stack design) and dynamic parameters (operating parameters) affecting durability. For PEMWE, stack design plays an important role in the electrolyzer performance and durability, such as the fabrication of the bipolar plate and the material selection of the stack components. Recently, novel stack designs have shown promising performance and durability enhancements by lowering the ohmic and mass losses, enabling constant clamping pressure inside the stack, and eliminating the degradation of the BPP plates by using 3D-printed plastic plates, which also greatly lower the cost of the stack. Operating parameters, including temperature, pressure, and water flow rate, can be regulated during operation. However, temperature and pressure have a more significant impact on PEMWE's performance and durability than water flow rate. Research on magnetic fields, ultrasonic power, pulsed power, and pressure swings has shown promising results in increasing gas removal rate to enhance PEMWE's performance by addressing intrinsic mass transport limitations. However, their application to large PEMWE systems has not been extensively tested. Further studies are needed to elucidate their mechanism and potential in PEMWE applications.     

The possibilities of cooperation between a hydrogen generator and a wind farm

In this paper, a hydrogen generator and a wind farm were taken as the research objects. The H₂ generator consisted characteristics of laboratory-tested electrolyzers were determined as a function of the hydrogen mass flow. Determining the auxiliary power index of the device allowed the efficiency of the hydrogen generator to be determined as a function of hydrogen mass flow as well as the hydrogen generator relative power. The dynamic characteristics of a generator were also presented. The possibility of a given wind farm cooperating with hydrogen generators that are characterized by different powers and various efficiencies was simulated. Algorithm enables determination of hydrogen generators efficiency for devices with various performance in nominal operation point is shown. It has been shown that proper selection of the power of the hydrogen generator in relation to the power of the wind farm can ensure a high efficiency for the device.     

Dynamic modeling of a solar hydrogen system under leakage conditions

Dynamic behaviors of an integrated solar hydrogen system have been modeled mathematically, which is based on a combination of fundamental theories of thermodynamics, mass transfer, fluid dynamics, and empirical electrochemical relationships. The model considers solar hydrogen system to be composed of three subsystems, i.e., solar cells, an electrolyzer, and a hydrogen tank. An additional pressure switch model is presented to visualize the hydrogen storage dynamics under a leakage condition. Validation of the solar hydrogen model system is evaluated according to the measured data from the manufacturer's data. Then, the overall was simulated by using solar irradiation as the primary energy input and hydrogen as energy storage for one-day operation. Finally, electrical characteristics and efficiencies of each subsystem as well as the entire system are presented and discussed.     

Evaluation of hybrid solar-wind-hydrogen energy system based on methanol electrolyzer

In this study, it is aimed to meet the annual electricity and heating needs of a house without interruption with the photovoltaic panel, wind turbine, methanol electrolyzer, and high temperature proton exchange membrane fuel cell system. The system results show that the use of the 2 WT with 18 PV was enough to provide the need of the methanol electrolyzer, which provides requirements of the high temperature proton exchange membrane fuel cell. The produced heat by the fuel cell was used to meet the heat requirement of the house with combined heat and power system. Electrical, thermal and total efficiencies of fuel cell system with combined heat and power were obtained as 38.54%, 51.77% and 90%, respectively. Additionally, the levelized cost of energy of the system was calculated as 0.295 $/kWh with combined heat and power application. The results of this study show that H₂ is useful for long-term energy storage in off-grid energy systems and that the proposed hybrid system may be the basis for future H₂-based alternative energy applications.     

Sizing of photovoltaic system coupled with hydrogen/oxygen storage based on the ORIENTE model

PEPITE is a project funded by the French ANR PAN-H research program. This project concerns, among various other tasks, a demonstration of a weather station electricity supply with help of a PV/FC/EL hybrid system located at the CEA center of Cadarache (France). To design a relevant sizing for this demonstration system, a complete sizing tool has been developed via a new numerical optimizing code named ORIENTE. It uses Matlab software based on sequential running time.     

Multi-state techno-economic model for optimal dispatch of grid connected hydrogen electrolysis systems operating under dynamic conditions

The production of hydrogen through water electrolysis is a promising pathway to decarbonize the energy sector. This paper presents a techno-economic model of electrolysis plants based on multiple states of operation: production, hot standby and idle. The model enables the calculation of the optimal hourly dispatch of electrolyzers to produce hydrogen for different end uses. This model has been tested with real data from an existing installation and compared with a simpler electrolyzer model that is based on two states. The results indicate that an operational strategy that considers the multi-state model leads to a decrease in final hydrogen production costs. These reduced costs will benefit businesses, especially while electrolysis plants grow in size to accommodate further increases in demand.     

Optimal operating conditions evaluation of an anion-exchange-membrane electrolyzer based on FUMASEP® FAA3-50 membrane

Hydrogen production via water electrolysis is considered the “greenest” way because it does not produce any direct carbon emissions when powered by renewable sources. Among the different technologies of electrolyzers, increasing interest is registered by that one based on anion-exchange membranes (AEMs). In this work, a FAA3-50 anion-exchange membrane (from FuMa-Tech) is used, after the KOH solution (1 M) exchange, as electrolyte/separator in an electrolysis cell of 5 cm² geometrical area. Commercial IrO₂ and 40% Pt/C catalysts are used at the anode and cathode, respectively, to evaluate the membrane under the most convenient conditions. The influence of cell temperature, membrane-electrode assembly (MEA) procedure (catalyst-coated membrane or catalyst coated electrode), and pure water or KOH solution on electrolyzer performance are analyzed. It appears that the catalyst-coated membrane approach, using the FAA3-50 membrane, allows higher temperature operation. However, diluted KOH solution is necessary to increase the membrane conductivity and the cell performance.     

Electrolyzer switching strategy for hydrogen generation from variable speed wind generator

This paper presents a new switching strategy for electrolyzer used in hydrogen generation which is connected to the terminal of a wind farm. The output of wind generator, in general, fluctuates greatly due to the random wind speed variations, which has a serious influence on the power system operation. In this study, the wind farm is composed of variable speed wind turbines (VSWT) driving permanent magnet synchronous generators (PMSG). The hydrogen generator (HG) is composed of rectifier and 10 electrolyzer units where each unit is controlled by the chopper circuit. To smoothen the wind farm line power, at first, a reference for the line power is generated from the difference of exponential moving average of wind farm output and its standard deviation. Then the switching strategy is developed in such a way that the proposed cooperative system can smoothen the wind farm line power fluctuation as well as generating hydrogen gas absorbing the fluctuating portion of wind farm output that lies above the reference line power. This novel switching strategy helps each electrolyzer unit working in full load and shift operation conditions and hence increases its lifespan and efficiency. The performance of the proposed system is investigated by simulation analyses, in which simulations are performed by using PSCAD/EMTDC.     

High temperature electrolysis using Molten Carbonate Electrolyzer

Molten Carbonate Fuel Cells (MCFC) are a well-developed and commercial technology that can operate also as an electrolyzer producing hydrogen from steam. In this study, a system for the production of hydrogen based on Molten Carbonate Electrolyzer (MCE) is presented. The system receives, as an external input, water and recovers internally the additional gas streams required as input to the electrolyzer. The system products are, separately, pure oxygen and hydrogen. A calculation sheet was implemented to analyze the energy equilibrium and gas mix compositions. The system can produce 0.074 Nl h^?1 cm^?2 of hydrogen with an inlet power density of 0.213 W cm^?2 for an energy consumption of 3.40 kWh Nm_H2^?3. Sensitivity studies on current density, utilization factors of both steam and CO₂ were analyzed considering energy equilibrium of the stack unit and the post processing processes. Results show how current density has higher impact on system equilibrium compared to the other parameters.     

Comparative experimental investigation of oxyhydrogen (HHO) production rate using dry and wet cells

Hydroxy gas was produced by water electrolysis from dry and wet cells using stainless steel 316L electrode of 136.5 cm² surface area and 4 mm separation. Electrolytes as NaOH and KOH of different concentrations were used. This study investigates the effect of electrolyte concentration, cell connection, electric current, operating time, electrolyte temperature and voltage on HHO productivity of the cells. Different plate configurations were studied. Increases of applied current, electrolyte temperature, electrolyte concentration and voltage led to the increase of gas production. More gas was produced from wet cell as compared to dry cell for the same design. HHO production for the dry cell reaches its maximum values of 866, 985, 1040 and 1090 ml/min at 5, 10, 15 and 20 g/L of NaOH at currents of 14, 18, 20 and 21.3 A and attains stable after about 30 min but the temperatures were increased till 32, 38, 44 and 52 °C, respectively and remained constant after that. The production peak values for wet cell were 975, 1160, 1325 and 1375 ml/min at 5, 10, 15 and 20 g/L of NaOH and flow currents of 17.8, 23.5, 26 and 27 A and remains constant after 90 min. At 10, 15 and 20 g/L NaOH, the temperatures were increased till constant values of 35, 44, 50 and 58 °C, respectively. HHO productivities from dry and wet cells are 866 and 1160 ml/min with electrolyzer efficiency of 72.1 and 69.3% at 14 and 18 A and (5 and 10 gm NaOH/L), respectively.