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Thermodynamical and Electrical Model of a PEM Electrolyzer Plant in the Megawatt Range
Abstract
During the next years, proton exchange membrane (PEM) electrolyzers with a capacity of several 100MW each, shall be built in the European Union. Currently, there are hardly any corresponding system models in the literature that can be used for simulating PEM electrolysis plants of this size. In particular, the generation of heat as a hydrogen by-product during electrolysis is commonly not considered. However, waste heat from larger plants can potentially be used for district heating. In this paper, a first approach of a detailed system model of a PEM electrolysis plant in the megawatt range is developed. The model parameters are based on values from the literature. This paper shows that the values for the exchange current density from the literature vary in a range of 10^9 , resulting in a large impact on the polarization curve. The result is a detailed PEM electrolyzer plant model, which is adapted to the Siemens Silyzer 300.
... Since the parameter calibration process for the fuel cell stack requires partial derivatives of the governing equations, these are discussed in detail. The electrochemical model of the PEM electrolyzer, together with a detailed discussion of the parameters involved and different models for them, is discussed in [9]. PEM fuel cell model. ...
Power-toGas to -X (PtGtX) systems consisting of PV cells, PEM electrolysis, hydrogen storage based on metal-hydrides, PEM fuel cells and buffer batteries could be used to meet heat and electricity demands of homes, businesses, or small districts. However, the actual size of the individual components and their interplay are crucial for the technical and economic feasibility for the respective application. Currently, there are hardly any tools available that can simulate power, fluid and heat flows of such systems simultaneously. In this paper, a multiphysical energy system simulation and analysis tool called MEgy is introduced. MEgy models electrochemical and thermodynamic processes. Innovations include calibration processes for parameters of the metal-hydride storage, PEM electrolyzer and PEM fuel cell, an extended degradation model for PEM fuel cells, an integration of modern equations of state for the fluids considered, and an own numerical solver for the arising differential-algebraic system of equations. A simulation model of a hydrogen lab is successfully set up based on experimental results.
KEYWORDS power-to-gas to -X, metal hydride storage, PEM, parameter calibration, energy network simulation, DAE solver.
... In addition, planned hydrogen generator plants as well as (possibly retrofitted) combined heat and power plants shall be taken into account. Respective models and data from [24] and [25] shall be incorporated. ...
A building's energy storage demand depends on a variety of factors related to the specific local conditions such as building type, self-sufficiency-rate and grid connection. Here we present a method to classify buildings of an urban building portfolio according to these criteria, in a newly developed bottom-up procedure. The algorithm uses publicly available building data such as building use, ground floor area, ridge height, solar roof potential, and population statistics. In addition, it considers the local gas grid (GG) as well as the district heating (DH) network. The building classification is developed for identifying typical building situations that can be used in a defined scenario to estimate the demand for residential energy storage capacity. In our case, the algorithm shall identify potential implementation of private photovoltaic(PV)-metal-hydride-storage(MHS) systems, for three scenarios, into the urban infrastructure for the city of Cologne. Since the data sets used are available for many German or European metropolitan areas, the method developed with the assumptions presented in this work, can be used for classification of other urban and semi-urban areas including the assessment of their grid infrastructure.
Power-toGas to -X (PtGtX) systems consisting of PV cells, PEM electrolysis, hydrogen storage based on metal-hydrides, PEM fuel cells and buffer batteries could be used to meet heat and electricity demands of homes, businesses, or small districts. However, the actual size of the individual components and their interplay are crucial for the technical and economic feasibility for the respective application. Currently, there are hardly any tools available that can simulate power, fluid and heat flows of such systems simultaneously. In this paper, a multiphysical energy system simulation and analysis tool called MEgy is introduced. MEgy models electrochemical and thermodynamic processes. Innovations include calibration processes for parameters of the metal-hydride storage, PEM electrolyzer and PEM fuel cell, an extended degradation model for PEM fuel cells, an integration of modern equations of state for the fluids considered, and an own numerical solver for the arising differential-algebraic system of equations. A simulation model of a hydrogen lab is successfully set up based on experimental results.
KEYWORDS power-to-gas to -X, metal hydride storage, PEM, parameter calibration, energy network simulation, DAE solver.
Polymer Electrolyte Membrane (PEM) electrolyzers will play a central role in future power-to-gas plants. Increasing the performance and scaling of PEM electrolyzers to the MW scale represents significant challenges for existing system components, as well as for optimal operational management. In relation to existing control loops, temperature control turns out to be critical. Due to scaling into higher performance classes and highly dynamic load profiles of green energy sources such as wind power and photovoltaics, the disturbance variable current density has an increasing influence on temperature control. The temperature is an essential operating parameter, especially for PEM electrolyzers, to be able to provide optimum efficiency, safety and prevent premature aging or destruction. In this article, we present an adaptive temperature control with a model-based feedforward control based on a model that considers the dependency of the operating parameters current density and stack temperature. In order to demonstrate the reliability and robustness of the control performance, an experimental validation of the adaptive temperature control with feedforward control is carried out on a 100 kW PEM electrolyzer. In this context, a comparison and an evaluation of the control concept to the existing proportional–integral–derivative (PID) control under highly dynamic load changes from wind power and photovoltaics is performed. Finally, the obtained results are discussed with respect to the aspects of optimal operational management.
For a transformation of current energy infrastructure towards 100% renewables, pipeline systems for natural gas have to be converted to ones for transporting hydrogen or synthetic gases containing hydrogen; this process needs intense planning and optimization based on simulations. Since known simulation tools were designed for natural gas primarily, they are expected to be not accurate enough for scenarios with hydrogen fractions above 10%. Hence, an efficient method for simulating transport of gases from renewable resources as well as impacts of hydrogen injection into gas networks is developed. This includes a method for setting up scenarios for analysis of impacts to long-distance networks for a country based on state-wise transient estimates for wind excess power. The simulation method employs transient non-isothermal Euler equations with the most recent equation-of-state of the European Gas Research Group (GERG-2008), a gas law allowing for hydrogen fractions up to 100 percent, and an approach for shifting compressor characteristics according to gas composition. In case of hydrogen and realistic scenarios, pressure ratios are between 1.025 and 1.075 only. For testing the overall method, a novel set of realistic long-distance gas transport scenarios with hydrogen injection nodes based on a study of wind power as well as power-to-gas plants installed in the federal states of Germany as well as a simple pipeline model for testing biogas, syngas, natural gas and hydrogen qualities were developed. Both models are analyzed with GERG in comparison with the commonly used alternative, showing that GERG is more accurate; depending on gas composition and scenario, differences between the commonly used detailed gas law and GERG can accumulate up to 2.8% in pressure and 6% in velocity for exemplary gases and a simple pipeline model with 100 km length. Additionally, the simulation process with GERG is at least as fast as with the commonly used gas law. Overall, GERG should be used. Moreover, results for the German transport scenarios indicate that with larger hydrogen injections, considerable flow shifts and locally quite different gas compositions over Germany can be expected, and a pure hydrogen network would need large additional injections, favorably from the northwestern part of Europe.
The objective of this paper is to present the modelling and experimental validation of the 46 kW PEM high pressure water electrolyzer installed on the MYRTE platform, which is a real-scale demonstrator that aims to study the deployment of hydrogen to store the energy associated to intermittent renewable energy source systems. An electrochemical steady-state and semi-empirical submodel coupled with a lumped thermal capacitance dynamic submodel is developed to predict the stack voltage and the stack temperature evolution from instantaneous operating conditions such as the applied current, the gas storage pressure tanks ( H 2 and O 2 ) and the ambient temperature. The Particle Swarm Optimization algorithm is used to find the electrochemical submodel parameters and a multivariable Matlab-Simulink® linked modular mathematical model is developed for validation. Results indicate that within a temperature range of 20–60 °C, and a pressure range of 15–35 bar, the stack voltage and the temperature evolution can be predicted even in transitory operating phases. The strategy used for the parameters identification is explained in detail and can be applied to any PEM water electrolyzer.
This review provides an exhaustive and comprehensive analysis of the existing modelling works about low temperature electrolysis system: alkaline and proton exchange membrane (PEM) technologies. In order to achieve this review, a classification was built, based on different criteria such as physical domains involved or modelling approaches. The proposed methodology allows both exposing an overview of the electrolysis system modelling field and providing a deep analysis of each reviewed model. Actual strengths, weaknesses and lacks in this research field are pointed out and the performed analysis provides ideas for future research in this area.
An enhanced model of a PEM electrolyser cell is presented, based on linked modular mathematical models of the anode, cathode, membrane and cell voltage. In addition to predicting the overall equilibrium electrolyser cell performance, based on parameters related to the materials of construction and the configuration of its components, the model is a powerful tool for exploring control strategies and understanding the contributions to cell voltage from the various internal components as a guide to researchers aiming for improved performance.
The purpose of this chapter is to provide an overview of the different water electrolysis technologies. In the introduction section, the general characteristics of water electrolysis (thermodynamics, kinetics, efficiency) are described. Main electrolysis technologies used to produce hydrogen and oxygen of electrolytic grade are then described in the following sections. Alkaline water electrolysis is described in Section 2.2, proton-exchange membrane water electrolysis in Section 2.3 and high-temperature water electrolysis in Section 2.4. For each technology, state-of-the-art performances are analyzed, limitations are identified and some perspectives are discussed.
We present here an isothermal, one-dimensional, steady-state model for a complete polymer electrolyte fuel cell (PEFC) with a 117 Nafion membrane. In this model we employ water diffusion coefficients electro-osmotic drag coefficients, water sorption isotherms, and membrane conductivities, all measured in our laboratory as functions of membrane water content. The model predicts a net-water-per-proton flux ratio of 0.2 H2O/H+ under typical operating conditions, which is much less than the measured electro-osmotic drag coefficient for a fully hydrated membrane. It also predicts an increase in membrane resistance with increased current density and demonstrates the great advantage of a thinner membrane in alleviating this resistance problem. Both of these predictions were verified experimentally under certain conditions.
In this work, a 1D polymer electrolyte membrane water electrolyzer (PEMWE) model that incorporates chemical degradation of the membrane is developed to study the influence of temperature and current density on the membrane degradation. In the 1D performance model, electronic and ionic transports through the different cell components are considered together with the electrochemical behavior of the anodic and cathodic catalyst layers. The membrane degradation model describes the oxygen cross-over from the anode to the cathode side, the formation of hydrogen peroxyde at the cathode side together with the subsequent formation of radicals via Fenton reactions involving metal-ion impurities and the membrane degradation. The development of the model is supported by specific single cell experiments to both validate the different modeling assumptions and determine some of the physical parameters involved in the performance and degradation models. The single-cell degradation tests confirm that most of the membrane degradation occurs at the cathode side and also show the strong influence of the temperature on the degradation rate. The effect of the current density on the degradation rate is more complex and presents a maximum at quite low current density. This phenomena, observed in the experiments, is well captured by the model. The model is then used to study the time evolution of the membrane thickness. The coupling between the performance and the chemical degradation models allows to capture the acceleration of membrane thinning.
Computational model of a proton exchange membrane (PEM) water electrolyzer is developed to enable investigation of the effect of operating conditions and electrolyzer components on its performance by expending less time and effort than experimental investigations. The work presents a dynamic model of a PEM electrolyzer system based on MATLAB/Simulink software. The model consists mainly of four blocks – anode, cathode, membrane and voltage. Mole balances on the anode and cathode blocks form the basis of the model along with Nernst and Butler–Volmer equations. The model calculates the cell voltage by taking into account the open circuit voltage and various over-potentials. The model developed predicted well the experimental data on PEM water electrolyzer available in the literature. The dynamic behavior of the electrolyzer system is analyzed and the effects of varying electrolyzer temperature and pressure on electrolyzer performance and over-potentials are presented.
Hydrogen is often considered the best means by which to store energy coming from renewable and intermittent power sources. With the growing capacity of localized renewable energy sources surpassing the gigawatt range, a storage system of equal magnitude is required. PEM electrolysis provides a sustainable solution for the production of hydrogen, and is well suited to couple with energy sources such as wind and solar. However, due to low demand in electrolytic hydrogen in the last century, little research has been done on PEM electrolysis with many challenges still unexplored. The ever increasing desire for green energy has rekindled the interest on PEM electrolysis, thus the compilation and recovery of past research and developments is important and necessary. In this review, PEM water electrolysis is comprehensively highlighted and discussed. The challenges new and old related to electrocatalysts, solid electrolyte, current collectors, separator plates and modeling efforts will also be addressed. The main message is to clearly set the state-of-the-art for the PEM electrolysis technology, be insightful of the research that is already done and the challenges that still exist. This information will provide several future research directions and a road map in order to aid scientists in establishing PEM electrolysis as a commercially viable hydrogen production solution.
We propose in this work a simple model for atmospheric or low-pressure PEM water electrolysers, which allows for simulating the electrochemical, thermal and H2 output flow behaviours with enough precision for engineering applications. The model has been validated by good agreement with experimental measurements performed in two different electrolysers. The electrochemical submodel allows for obtaining the operating stack voltage from the input current and the stack temperature conditions. After non-linear fitting and statistical analysis from experimental data we conclude that the electrochemical submodel can be extrapolated for any PEM water electrolyser knowing two parameters with physical meaning: activation energy of the “water oxidation” for the anode electrocatalyst and the activation energy for proton transport in the solid polymer membrane. This submodel was validated with experimental polarisation curves at different temperatures from two different PEM water electrolysers. The standard err
The performance of a 6 kW proton exchange membrane (PEM) electrolyzer was modeled using a semiempirical equation. Total cell voltage was represented as a sum of the Nernst voltage, activation overpotential and ohmic overpotential. A temperature and pressure dependent Nernst potential, derived from thermodynamic principles, was used to model the 20 cell PEM electrolyzer stack. The importance of including the temperature dependence of various model components is clearly demonstrated. The reversible potential without the pressure effect decreases with increasing temperature in a linear fashion. The exchange current densities at both the electrodes and the membrane conductivity were the coefficients of the semiempirical equation. An experimental system designed around a 6 kW PEM electrolyzer was used to obtain the current–voltage characteristics at different stack temperatures. A nonlinear curve fitting method was employed to determine the equation coefficients from the experimental current–voltage characteristics. The modeling results showed an increase in the anode and cathode exchange current densities with increasing electrolyzer stack temperature. The membrane conductivity was also increased with increasing temperature and was modeled as a function of temperature. The electrolyzer energy efficiencies at different temperatures were evaluated using temperature dependent higher heating value voltages instead of a fixed value of 1.48 V.
This work aims at analysing the performances of a prototype of a high pressure Polymer Electrolyte Membrane water electrolyser.The whole work was funded in the framework of the Italian FISR (Research special supplementary funding) project. The high pressure electrolyser prototype was manufactured by Giner Inc. (Massachusetts, USA), whereas the test bench was expressly designed and built thanks to the collaboration with LAQ INTESE (High Quality Laboratory – Technological Innovation for Energetic Sustainability) and with Sapio SpA (Monza, Milan, Italy).An electrochemical model of the electrolyser stack is developed, which calculates the theoretical open-circuit voltage via a thermodynamic analysis of the process, and then obtains the expected real voltage during operation by calculating the different overvoltages as function of the current. The final result of the model is a theoretical polarisation curve.Experimental results are then presented and compared with the model theoretical results, and thanks to an experimental data fitting it is possible to obtain the estimated values of some important process parameters and their trend in different temperature and pressure conditions.
Water electrolysers using proton exchange membranes (PEM) offer high prospective potentialities for the production of pure hydrogen. The basic components of PEM electrolysis cell stacks are membrane, electrocatalytic layers, porous current collectors and bipolar separating plates. The work presented in this paper is devoted to the optimization of the structure of the current collectors, the role of which is to provide efficient electric contact and gas/water transport between electrocatalytic layers and bipolar plates. Using both experiments and modelling, optimum pore sizes, thickness and porosities have been determined for operation at high current densities (above 1 A.cm −2).
In this paper a study of the thermal performance of a commercial alkaline water electrolyzer (HySTAT from Hydrogenics) designed for a rated hydrogen production of 1 N m3 H2/h at an overall power consumption of 4.90 kW h/N m3 H2 is presented. The thermal behaviour of the electrolyzer has been analyzed under different operating conditions with an IR camera and several thermocouples placed on the external surface of the main electrolyzer components. It has been found that the power dissipated as heat can be reduced by 50–67% replacing the commercial electric power supply unit provided together with the electrolyzer by an electronic converter capable of supplying the electrolyzer with a truly constant DC current. A lumped capacitance method has been adopted to mathematically describe the thermal performance of the electrolyzer, resulting in a thermal capacitance of 174 kJ °C−1. The effect of the AC/DC converter characteristics on the power dissipated as heat has been considered. Heat losses to the ambient were governed by natural convection and have been modeled through an overall heat transfer coefficient that has been found to be 4.3 W m−2 °C−1. The model has been implemented using ANSYS® V10.0 software code, reasonably describing the performance of the electrolyzer. A significant portion of the energy dissipated as heat allows the electrolyzer operating at temperatures suitable to reduce the cell overvoltages.
Temperature dependency of the charge transfer coefficient (CTC) of the oxygen electrode of a commercial proton exchange membrane electrolyzer stack is investigated in this paper. A good estimate of the CTC is important in predicting the current–voltage characteristics of electrolyzers. The estimated CTC also provides insight into the properties of the electrode. The results of this study show that at typical operating temperatures, there is a reasonable variation of the CTC from the symmetry factor. The results indicate that within a temperature range of 20–60 °C, the average CTC changes from 0.18 to 0.42 which is clearly lower than the standard symmetry factor of 0.5.
Shell starts up Europe's largest PEM green hydrogen electrolyser
- Refhyne
REFHYNE. Shell starts up Europe's largest PEM green hydrogen electrolyser, July 2021 URL:
https://www.refhyne.eu/shell-starts-up-europes-largest-pem-green-hydrogen-electrolyser/
[Accessed: 8-June-2022]
Heat Management of PEM Electrolysis: A study on the potential of excess heat from mediumto largescale PEM electrolyisis and the performance analysis of a dedicated cooling system
- W J Tiktak
Tiktak, W. J., Heat Management of PEM Electrolysis: A study on the potential of excess heat
from mediumto largescale PEM electrolyisis and the performance analysis of a dedicated cooling
system." Delft, 2019, https://resolver.tudelft.nl/uuid:c046820a-72bc-4f05-b72d-e60a3ecb8c89
[Accessed: 26-November-2021]
- Vdi-Wärmeatlas
VDI-Wärmeatlas, Berlin, Heidelberg, Springer Berlin Heidelberg, 2013, ISBN: 978-3-64219980-6, DOI: 10.1007/978-3-642-19981-3
The global energy transition will be based on the hydrogen economy
- Siemens Energy
Siemens Energy, The global energy transition will be based on the hydrogen economy, 2021,
URL:
https://press.siemens-energy.com/global/de/feature/die-globale-energiewende-wird-aufder-wasserstoffwirtschaft-basieren
At the Dawn of the Hydrogen Economy, POWER -Access Intelligence
- A Schnettler
Schnettler, A., At the Dawn of the Hydrogen Economy, POWER -Access Intelligence,
01.07.2020, URL: https://www.powermag.com/at-the-dawn-of-the-hydrogen-economy