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... hydrogen with greater efficiency [57,59]. Solid oxide electrolysis operates at high pressure and high temperatures 500-850 °C and utilizes the water in the form of steam. Solid oxide electrolysis process conventionally uses the O 2À conductors which are mostly from nickel/yttria stabilized zirconia [60], operating principle of SOE has shown Fig. 3. Nowadays, some of the ceramic proton conducting materials have been developed and studied in solid oxide fuel cells. However, increasing the much attention towards ceramic proton conducting materials for SOE electrolysis process, due to these materials demonstrates high efficiency and superior ionic conductivity than O 2À conductors ...
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... Polymer-electrolyte-membrane (PEM) electrolysis has the advantage of being able to handle fast load changes, making it suitable for dynamic and part-load operation. This allows it to be easily combined with highly fluctuating electricity from renewable sources such as wind and solar [1]. Overall, the electrolysis cell's anode produces molecular oxygen through the chemical reaction 2H 2 0 →O 2 + 4H + + 4e − [2]. ...
... The former is anticipated to be a pure oxygen atmosphere of 1 bar [30]. The latter falls between 20 and 80 • C in PEM electrolysis systems [1] and was set to 50 • C. Furthermore, the super-saturation is assumed to be σ = 3 at the inlet of the pipe [31]. Regarding the density function of the nucleation site diameters discussed in section 3.3.1, ...
The formation of oxygen bubbles in the anodic circuit of a polymer electrolyte membrane (PEM) electrolyser is a major technological problem as it greatly affects heat transfer, process performance and safety. Overall, bubbles evolve in the pipe flow upstream of the gas separator due to oxygen super-saturation created by the chemical reaction at the anode. The accurate prediction of bubble formation in the pipes is important for the correct positioning and design of the gas separator. This paper therefore presents a cell-based one-dimensional numerical model that estimates bubble evolution in a horizontal pipe-flow. For this purpose, the model considers bubble growth at nucleation sites and in the flow, enabling the prediction of the corresponding gas fraction at different locations within the cooling circuit. Furthermore, a sensitivity analysis was conducted based on the derived model to evaluate the impact of various parameters on the degassing rate. It was found that the smaller the pipe diameter, the greater the initial gas content and the greater the number of nucleation sites, the shorter the pipe length required to achieve solubility.
... Driven by the political and societal endeavors to drastically reduce CO 2 emissions, the substitution of fossil fuels by green hydrogen is widely considered [1]. Electrochemical splitting of water inside polymer electrolyte membrane water electrolyzers (PEMWEs) is one possibility for efficient and sustained production of green hydrogen [2,3]. A key aspect of the commercialization of PEMWE is improving its performance at high current densities. ...
Investigating the counter-current two-phase flow within the anodic porous transport layer (PTL) of polymer electrolyte membrane water electrolyzers (PEMWEs) is a complex yet intriguing challenge. Until now, the gas-liquid invasion processes inside PTLs are only to a limited extent accessible under operation conditions, usually using sophisticated and expensive optical approaches, i.e., neutron imaging. We propose a model-supported experimental method with a fully operating microfluidic PEMWE, that allows to examine pore-scale oxygen-water distributions at the anode with high spatial and temporal resolution. The microfluidic cell is made of transparent Poly-Methyl-Methacrylate (PMMA), and the PTL is simplified by a quasi-2D pore network (PN) with a uniform pore-throat structure in the first preliminary study. The proposed setup is a significant advancement over previous studies, where gas was only injected at a constant flow rate from a single point. Test cases with current densities of 0.1, 1, and 2 A/cm 2 and water flow rates of 1, 3, 5, and 10 ml/min were realized in the novel setup. We found periodically alternating invasion of oxygen (drainage) and water (imbibition), which were analyzed based on image sequences as well as voltage measurements. The experimental data is additionally supported by pore-scale Lattice Boltzmann (LB) and PN simulations. The preliminary results with the simplified PN structure are used to study the dominating transport mechanisms, revealing that drainage and imbibition occur simultaneously and are affected by evaporation and wetting liquid films formed in sharp pore corners. These phenomena are also expected to occur in more complex PTL structures. The preliminary results can, therefore, be regarded as an important basis for PTL studies, which are structurally more complex.
... To overcome these serious threats, new energy solutions are advancing toward a sustainable economy and a secure living style [6], such as relying on low-impact renewable energy sources on our environment. In this sense, the clean energy industry is turning towards hydrogen (H 2 ) production as a potential alternative to fossil fuels due to its highly efficient combustion process that can produce up to 1.4 × 10 5 kJ/kg of energy while emitting only water as a by-product [7][8][9]. Given that current steam-based H 2 production requires fossil fuels, resulting in CO 2 emissions, it is essential to develop a clean, renewable, and efficient pathway for H 2 production to ensure the sustainable development of the H 2 economy [10]. ...
The focus on sustainable energy sources is intensifying as they present a viable alternative to conventional fossil fuels. The emergence of clean and renewable hydrogen fuel marks a significant technological shift toward decarbonizing the environment. Harnessing mechanical and thermal energy through piezoelectric and pyro-electric catalysis has emerged as an effective strategy for producing hydrogen and contributing to reducing dependence on carbon-based fuels. In this regard, this review presents recent advances in piezoelectric and pyroelectric catalysis induced by mechanical and thermal excitations, respectively, towards hydrogen generation via the water splitting process. A thorough description of the fundamental principles underlying the piezoelectric and pyroelectric effects is provided, complemented by an analysis of the catalytic processes induced by these effects. Subsequently, these effects are examined to propose the prerequisites needed for such catalysts to achieve water splitting reaction and hydrogen generation. Special attention is devoted to identifying the various strategies adopted to enhance hydrogen production in order to provide new paths for increased efficiency.
... Schematic representation of an (left) AWE and (right) PEMEL (adapted from[20]). ...
... Schematic representation of an SOEC (adapted from[20]). ...
Accelerating the transition to a cleaner global energy system is essential for tackling the climate crisis, and green hydrogen energy systems hold significant promise for integrating renewable energy sources. This paper offers a thorough evaluation of green hydrogen’s potential as a groundbreaking alternative to achieve near-zero greenhouse gas (GHG) emissions within a renewable energy framework. The paper explores current technological options and assesses the industry’s present status alongside future challenges. It also includes an economic analysis to gauge the feasibility of integrating green hydrogen, providing a critical review of the current and future expectations for the levelized cost of hydrogen (LCOH). Depending on the geographic location and the technology employed, the LCOH for green hydrogen can range from as low as EUR 1.12/kg to as high as EUR 16.06/kg. Nonetheless, the findings suggest that green hydrogen could play a crucial role in reducing GHG emissions, particularly in hard-to-decarbonize sectors. A target LCOH of approximately EUR 1/kg by 2050 seems attainable, in some geographies. However, there are still significant hurdles to overcome before green hydrogen can become a cost-competitive alternative. Key challenges include the need for further technological advancements and the establishment of hydrogen policies to achieve cost reductions in electrolyzers, which are vital for green hydrogen production.
... Moreover, Kazakhstan is actively exploring opportunities to export green hydrogen to places like China and Europe. Water electrolysis is among the methods employed for hydrogen production intended for export, and research and development endeavors are underway in this domain (Kumar et al. 2019;Ergazieva et al. 2020). ...
... The principle of obtaining hydrogen from renewable sources has been analyzed in several studies [5,6], in which various types of electrolyzers have been analyzed [7][8][9] and positive results have been shown. ...
... PEM water electrolysis is one of the favorable methods for the conversion of renewable energy into high pure hydrogen, which is one of the reasons researchers are developing methods for its use in power systems with renewable sources [25]. Figure 5 illustrates the principle of a PEM electrolyzer [6]. When an electric current is applied, water molecules are separated into oxygen and hydrogen protons and electrons. ...
With the increasing use of renewable energy sources and decentralized power systems, certain challenges have emerged in meeting consumers’ electrical energy demands. The intermittent nature of renewable energy generation means that it cannot always align with consumers’ needs, resulting in periods of excess energy production when it is not required. To bridge this gap between production and consumption, energy storage systems are necessary. This paper defines the work of an isolated microgrid, which consists of renewable sources (wind and PV) for energy production, households with electric vehicles as consumers, and a combined storage system. This storage system is made from batteries, hydrogen storage, and a control system that defines the best use of the storage. Stored energy is utilized through fuel cells to generate electricity for consumption when renewable sources cannot meet the demand. This paper presents the principles of electrolysis and models of individual elements within such a system, as well as the definition and principle of control of the system functionality based on rules and conditions. The proposed control system aims to increase the energy storage lifecycle by deciding when and how to utilize which type of storage and define a self-sufficient microgrid based on renewable sources of production. An economic analysis of the storage part of the system was carried out in which the levelized cost of energy stored and the NPC of the storage systems are calculated. A simulation of the system’s operation is conducted using one-hour measurements of wind turbines, solar panels, and household consumption in Serbia. To analyze the system’s behavior, a one-week time horizon is considered.
... For instance, metal and/or metal-oxide-based catalysts have received much attention due totheirlowcost, morphology and facets, as well as defect-tuned optoelectronic properties, which are favorable for overall water splitting [14][15][16][17][18][19]. Nonetheless, their inherent disadvantages such as low charge mobility and self-degradation have thus far resulted in low conversion efficiency and stability [20][21][22]. ...
Robust engineering of two-dimensional (2D) materials via covalent grafting of organic molecules has been a great strategy for permanently tuningtheir physicochemical behaviors toward electrochemical energy applications. Herein, we demonstrated that a covalent functionalization approach of graphitic surfaces including graphene by a graftable porphyrin (g-Por) derivative, abbreviated as g-Por/HOPG or g-Por/G, is realizable. The efficiency of this approach is determined at both the molecular and global scales by using a state-of-the-art toolbox including cyclic voltammetry (CV), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, atomic force microscopy (AFM), and scanning tunneling microscopy (STM). Consequently, g-Por molecules were proven to covalently graft on graphitic surfaces via C-C bonds, resulting in the formation of a robust novel hybrid 2D material visualized by AFM and STM imaging. Interestingly, the resulting robust molecular material was elucidated as a novel bifunctional catalyst for both the oxygen evolution (OER) and the hydrogen evolution reactions (HER) in acidic medium with highly catalytic stability and examined at the molecular level. These findings contribute to an in-depth understanding at the molecular level ofthe contribution of the synergetic effects of molecular structures toward the water-splitting process.
... A comprehensive review on current technologies of hydrogen compression based on mechanical, cryogenic, electrochemical, adsorption and metal hydride compressors (MHHCs) has been discussed previously [129][130][131]. Of the compressors examined, MHHCs pose an interesting avenue, due to the reduced number of moving parts and the fact they are driven thermally. ...
This article presents a comprehensive review of the current landscape and prospects of large-scale hydrogen storage technologies, with a focus on both onshore and offshore applications, and flexibility. Highlighting the evolving technological advancements, it explores storage and compression techniques, identifying potential research directions and avenues for innovation. Underwater hydrogen storage and hybrid metal hydride compressed gas tanks have been identified for offshore buffer storage, as well as exploration of using metal hydride slurries to transport hydrogen to/from offshore wind farms, coupled with low pressure, high flexibility electrolyser banks. Additionally, it explores the role of metal hydride hydrogen compressors and the integration of oxyfuel processes to enhance roundtrip efficiency. With insights into cost-effectiveness, environmental and technology considerations, and geographical factors, this review offers insights for policymakers, researchers, and industry stakeholders aiming to advance the deployment of large-scale hydrogen storage systems in the transition towards sustainable energy.
... These technologies follow different methods of achieving electrolysis, mainly with how they use different charge carriers and environments in which the electrolysis takes place [4]. The PEM electrolysis systems, in comparison to the aforementioned technologies, can respond rapidly to varying power inputs and therefore can be easily integrated with renewable energy systems [5]. The PEM technology also offers lower operating temperatures, robustness, flexibility in fuel types, high power density, fast start-up and fewer problems with corrosion and leaks [6]. ...
... The constants 1 and 2 are defined as follows: Proposed Polymer Electrolyte Membrane electrolyser model to produce green hydrogen When the wind energy system generates more power than the load demands, the electrolyser splits water into hydrogen and oxygen using the excess energy. The amount of power ( ) available for the electrolyser is computed following the schematic representation in Figure 1 as: (5) where mppt = 98 % is the MPPT power efficiency; load is the power required by the load; bat = 80% is the battery bank charge efficiency, and inv = 98% is the inverter efficiency. ...
... PEM electrolyzers were initially favored over alkaline electrolyzers for renewable electricity sources because they were thought to respond better to the intermittent behavior of the renewables [28]. However, in papers such as Bos et al. [25] and Ince et al. [29], alkaline electrolyzers were also coupled with wind turbines or a PV plant without the application of hydrogen storage. ...
