Which types of electrolyzers can also be used as fuel cells?5 answersAnion-exchange membrane (AEM) technologies, such as AEM water electrolyzers (AEMWEs) and fuel cells (AEMFCs), are versatile in their ability to both transform and utilize renewable resources, indicating their dual functionality as both electrolyzers for hydrogen production and fuel cells for hydrogen utilization. Similarly, solid oxide electrolyzer (SOE) technology, particularly in its metal-supported cell configurations, demonstrates potential for reversible operation, contributing to energy storage and the production of green fuels, suggesting its capability to function in a dual role as well. The integration of electrolyzers (EL) and fuel cells (FC) in green hydrogen energy storage systems further supports the concept of dual-use technologies, where stored hydrogen can be converted back to electrical energy, showcasing the reversible functionality of such systems.
Alkaline electrolyzers (AELs) based on platinum on Vulcan cathodes and stainless-steel anodes, optimized for high-current density operation, although primarily designed for electrolysis, could theoretically be adapted for fuel cell applications due to their high efficiency and durability. The transition from proton exchange membrane fuel cells to AEMFCs, with their compatibility with non-Pt-group metals, suggests a flexibility in component materials that could be leveraged in reversible systems. While not directly stated, the advancements in CO2 conversion and hydrogen production through water electrolysis hint at the underlying potential for reversibility in these systems, especially when considering the broader context of renewable energy integration and storage.
Solid oxide electrolysis cells (SOECs) are highlighted for their high operating temperatures and favorable thermodynamics, which not only make them efficient for electrolysis but also suggest their potential reversibility for use in fuel cell applications, especially when considering their integration with chemical syntheses. The development of CO2 electrolyzers using polymer electrolyte based gas-diffusion electrodes, while focused on CO2 reduction, introduces materials and designs that could be adaptable for fuel cell operations, given the emphasis on efficient gas diffusion and electrolyte performance.
Polymer electrolyte membrane (PEM) electrolyzers, known for their high efficiency in converting electricity into hydrogen, utilize components and interfaces that could potentially be optimized for reverse operation as fuel cells, as indicated by studies on interface morphology and transport dynamics. Lastly, the exploration of gas diffusion electrodes in CO2 reduction, with a focus on maintaining optimal local pH levels for high selectivity and efficiency, introduces design considerations that could be relevant for reversible fuel cell applications, especially in managing the electrolyte environment.
In summary, AEM technologies, SOEs, and PEM systems, along with advancements in electrolyzer design and operation, suggest a broad potential for these devices to be used not only for electrolysis but also as fuel cells, highlighting the versatility and dual functionality inherent in these systems.
How to improve techno economic assesment for PEM electrolysis?7 answersImproving the techno-economic assessment (TEA) for Proton Exchange Membrane (PEM) electrolysis involves a multifaceted approach that integrates advancements in technology, optimization of operational parameters, and economic analysis to enhance system performance and reduce costs. Firstly, integrating wastewater treatment plants into green hydrogen networks can provide a dual benefit of utilizing oxygen produced in PEM electrolysis for biological treatment, potentially reducing the net costs of production (NCP) for oxygen, which in turn affects the overall economics of PEM electrolysis positively. Additionally, exergoeconomic analysis, which combines exergy and economic analyses, can help understand the interplay between system costs and performance, highlighting the importance of optimizing operating conditions such as temperature, pressure, and membrane thickness to improve efficiency and reduce costs.
Moreover, exploring alternative storage options like ammonia synthesis from green hydrogen can provide insights into cost reduction strategies for the broader hydrogen production and utilization ecosystem, which indirectly benefits the economic assessment of PEM electrolysis by showcasing viable end-use applications. A comprehensive overview of electrolysis systems, including technical and economic modeling, is crucial for accurate TEA, emphasizing the sensitivity of economic outcomes to variations in key input parameters.
The development of models for hydrogen production via offshore wind electrolysis demonstrates the potential for significant cost reductions through direct coupling of renewable energy sources with electrolysis systems, suggesting a pathway to lower hydrogen production costs. Addressing the economic trade-offs between key performance variables in CO2 electrolysis through multiscale modeling can also provide valuable insights for optimizing PEM electrolysis operations. Assessing the production of liquid electrofuels via PEM electrolysis highlights the importance of considering environmental impacts alongside economic factors, promoting a more sustainable energy transition.
Investigating the techno-economic performance of large-scale renewable energy and electrolysis systems reveals the potential for achieving economic equilibria that benefit both renewable energy sources and electrolysis operations, suggesting a win-win scenario for green hydrogen production. Financial metrics such as Levelised Cost of Hydrogen (LCH) and Net Present Value (NPV) are essential for evaluating the economic attractiveness and market flexibility of PEM electrolysis technologies, guiding investment decisions. Lastly, a systematic techno-economic assessment of low-temperature CO2 electrolysis products can prioritize technological developments and propose guidelines to facilitate market adoption, indirectly supporting the economic viability of PEM electrolysis by expanding its application scope.
What are the characteristics of PEM electrolyzers?4 answersPEM electrolyzers have several characteristics. They are used for hydrogen production through water electrolysis. PEM electrolyzers utilize a proton exchange membrane, which enables superior energy efficiency, higher hydrogen purity, and high flexibility. The development of PEM electrolyzers aims to achieve higher energy efficiency, minimize capital costs, and enable sustainable hydrogen production on a larger scale. Mass transport is crucial in PEM electrolyzers, as water must be supplied to the catalyst layer while oxygen bubbles are eliminated. The performance of PEM electrolyzers depends on the combined effect of heat and mass, especially at high voltages. Increasing the inlet temperature can improve the kinetic reaction rate and reduce the ohmic resistance, promoting performance improvement. Decreasing the thickness of the membrane can significantly improve performance but may increase the membrane temperature at high voltage.
What are the material used for electrode catalysts in electrolysis?5 answersElectrode catalysts used in electrolysis include platinum and other precious metals, as well as transition metal chalcogenides such as molybdenum sulfide. Single-atom catalysts (SACs) have also shown promise, with noble metals and transition metals supported by various materials serving as the catalysts. Nickel sulfide-based chalcogenide materials, particularly those doped with various transition metals, have been studied for their excellent catalytic activity in oxygen evolution reactions (OERs). Additionally, an electrode for electrolysis can contain elemental ruthenium, elemental iridium, elemental titanium, and a first transition metal element such as Sc, V, Cr, Fe, Co, Ni, Cu, or Zn. The preparation of catalytic materials for electrochemical reduction reactions involves electrolysis of precursor solutions containing group VIB metals, impregnation of an electrically conductive support with the solution, drying, and sulfurization.
What are the different PV systems configurations combined with alkaline and PEM water electrolyzers for hydrogen production?5 answersDifferent PV system configurations combined with alkaline and PEM water electrolyzers for hydrogen production have been studied in the literature. The first study by Urs et al. compares different configurations of PV systems with monofacial or bifacial PV modules and mounted or single-axis structures for utility scale PV sizes in Abu Dhabi. They identify the best configuration to be a single-axis tracking structure with bifacial PV modules. Nejadian et al. conduct a comparative analysis and techno-economic optimization of three integrated energy systems for hydrogen, power, and desalinated water production. They compare the performance of solid oxide electrolyzer cell (SOEC), polymer electrolyte membrane electrolyzer (PEM), and alkaline electrolyzer in an integrated system and find that the alkaline system has the cheapest hydrogen cost. Xia et al. propose an optimal current pulse-width modulation control strategy for alkaline water electrolyzers driven by photovoltaic arrays, which enhances their low-load performance and allows them to follow fluctuating photovoltaic power.
What cheaper alternatives to Titanium can be used as catalysts in hydrogen batteries?5 answersCheaper alternatives to titanium as catalysts in hydrogen batteries include molybdenum disulfide (MoS2) films on titanium substrates. These films have been shown to have high catalytic activity for the hydrogen evolution reaction (HER) and exhibit electroactivity. Another alternative is the use of single-atom metals on a carbon matrix, such as V, Mn, Fe, Co, Ni, Cu, Ge, Mo, Ru, Rh, Pd, Ag, In, Sn, W, Ir, Pt, Pb, and Bi. These single-atom catalysts (SACs) have been found to enhance the performance of electrochemical reactions, including HER, and have potential applications in energy conversion and storage.