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Proton exchange membrane (PEM) electrolysis is widely considered an integral part of the energy transition. Thinner membranes can reduce Ohmic losses and increase efficiency. However, hydrogen crossover limits the use of thinner membranes. For the first time, this review provides a comprehensive overview of both model and experimental works on hydrogen crossover and crossover mitigation. By combining the experimental data and state-of-the-art models, we discuss the recent progress in understanding crossover mechanisms. The dominant mechanism for hydrogen crossover is the diffusion driven by both the high hydrogen partial pressures at the cathode and supersaturation in the catalyst layer due to transport limitations. The reviewed models successfully reproduce the experimental data obtained by different groups. A variety of strategies for including recombination catalysts in the cell are currently investigated in academic and corporate research. Some of these show promising results with potential for near-term industrial application. • H 2 crossover conventionally limits the use of thin membranes in PEM electrolysis. • Supersaturation and electroosmotic water drag can significantly affect gas crossover. • Mechanistic crossover models describe various experimental results accurately. • Recombination catalysts mitigate safety issues associated with H 2 crossover. • Multiple approaches for including recombination catalysts in MEAs are promising. [ABSTRACT FROM AUTHOR]

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This work examines the electrochemically enhanced production of succinic acid using the bacterium Actinobacillus succinogenes. The principal objective is to enhance the metabolic potential of glucose and CO2 utilization via the C4 pathway in order to synthesize succinic acid. We report on the development of an electro-bioreactor system to increase succinic acid production in a power-2-X approach. The use of activated carbon fibers as electrode surfaces and contact areas allows A. succinogenes to self-initiate biofilm formation. The integration of an electrical potential into the system shifts the redox balance from NAD+ to NADH, increasing the efficiency of metabolic processes. Mediators such as neutral red facilitate electron transfer within the system and optimize the redox reactions that are crucial for increased succinic acid production. Furthermore, the role of carbon nanotubes (CNTs) in electron transfer was investigated. The electro-bioreactor system developed here was operated in batch mode for 48 h and showed improvements in succinic acid yield and concentration. In particular, a run with 100 µM neutral red and a voltage of −600 mV achieved a yield of 0.7 gsuccinate·gglucose−1. In the absence of neutral red, a higher yield of 0.72 gsuccinate·gglucose−1 was achieved, which represents an increase of 14% compared to the control. When a potential of −600 mV was used in conjunction with 500 µg∙L−1 CNTs, a 21% increase in succinate concentration was observed after 48 h. An increase of 33% was achieved in the same batch by increasing the stirring speed. These results underscore the potential of the electro-bioreactor system to markedly enhance succinic acid production.

This study aimed to investigate the waste streams from the production of hydrogen energy carriers from PtX technology and identify how they can be valorized by applying a symbiotic approach to enable greater utilization of the inputs and outputs from such plants. Various electrolysis development projects are under development or in the pipeline in Europe and Denmark, but in many cases, it is not clear how waste streams are emphasized and valued in these projects. Thus, three exploratory case studies (a city, a rural, and an energy hub case) were investigated herein exemplifying state-of-the-art electrolysis projects currently being deployed, with a focus on identifying how and to what extent waste streams are being valorized in these projects and energy system integration is being pursued. Inspired by the industrial symbiosis literature, we analyzed how internal, regional, and long-distance symbiotic collaboration is realized within these cases and found them to be very different in terms of the energy carrier produced, the current development stage, and the access to appropriate energy infrastructure. This paper concludes that the co-location of PtX technology near biogas plants would provide a great opportunity for the integration of the produced energy carriers and waste streams into the existing energy system and, hence, could assist in stabilizing fluctuating renewable energy sources to enable their more efficient use in the energy system.

In the past, neutron imaging has been the little brother of advanced neutron spectroscopy techniques due to its apparent simplicity. However, this simplicity allows the studying of complex chemical and electrochemical processes and related devices even under harsh reaction conditions such as high pressure, high temperature, corrosive and/or air sensitive environments. We review a number of highly relevant case studies as archetypal examples of modern energy technology; that is heat storage, power-to-X, batteries, fuel cells, and catalysis. The promising results trigger the further development of neutron imaging towards a chemical imaging method.

To maintain a global zero-emission policy and a high standard of living, new energy systems with higher system efficiency and net zero-emission productions need to be designed and deployed. This paper describes a novel integrated system between a direct-fired supercritical carbon dioxide (sCO2) power system with hydrogen and oxygen for zero-emission power generation and storage. sCO2 power cycles offer higher thermodynamic efficiencies than conventional gas-fired Brayton cycles. Heat is added to the system from the combustion of hydrogen and oxygen. The system consists of an electrolyzer unit and two cryogenic storage systems for hydrogen and oxygen. The proposed system is designed as a medium/long-term battery that can use excess electricity from the grid to produce hydrogen (electrolyzer) and supply to the grid (hydrogen combustion) in times of higher demand. Nitrous oxide emissions are mitigated by oxy-combustion and water separation from the post-combustion products allows for a closed-loop water cycle. The optimization of cycle parameters suggests a turbine inlet temperature of 1473 K and a pressure of 30 MPa for a specific net power output of 348 kJ/kg electrical. This results in an H2-sCO2 direct-fired power cycle efficiency of around 53 % with an overall system round-trip efficiency of up to 35 %.

The urgency for energy transition is evident through the increasing demand for new technologies such as water electrolysers (WEs), which have the potential to generate green hydrogen using renewable electricity. This paper aims to provide a comprehensive overview of the technical capabilities of commercially available WE system products. The analysis is based on publicly accessible data gathered from 28 WE manufacturers worldwide with a total of 186 products, focusing on technology types and various technical characteristics of each WE system, including capacity, footprint, hydrogen output pressure, hydrogen purity and conversion rate. The analysis reveals that the current WE system solutions in the market exhibit diverse and varied characteristics. Further, there is a lack of standardized product specifications adopted by manufacturers. This underscores the urgent need for the development of frameworks and standards. Implementing such standards is crucial for enhancing clarity and understanding, facilitating efficient comparisons and selection processes, and supporting the future advancement of WE technologies and WE-enabled Power-to-X applications on a global scale. [ABSTRACT FROM AUTHOR]

The hydrogen economy is of crucial importance in energy policies worldwide. Moreover, there are many benefits to producing biomethanol because it can be used in engines to achieve high efficiency, zero emission and lower risks of flammability. This research aims to evaluate a biomethanol and natural gas generation system that uses biomass gasification and high-temperature electrolysis. Thermal integration is applied between the steam generators of the gasifier and electrolyzer. The LNG regasification unit and an open Brayton cycle are responsible for power and natural gas production. The flue gas leaving the gas turbine leads to additional production of biomethanol. Oxygen management is applied between three different subsystems and there is a large amount of CO 2 utilization as well. The results of energy analysis and thermodynamic modelling of an integrated system conducted in Aspen Plus indicate that the proposed cycle produces 16 644 ton/yr of natural gas, 1412 ton/yr of biomethanol, uses 3450 ton/yr of CO 2 , and has an efficiency of 81.96 %. Raising the methanol reactor temperature from 220 °C to 350 °C significantly enhances biomethanol capacity from 1015 ton/yr to 1930 ton/yr, leading to a 4 % increase in total energy efficiency. • The biofuels plant integrates gasifier, electrolyzer, and water-gas-shift reactor. • Energy efficiency of 81.96 % and CO 2 utilization of 3450 ton/yr are obtained. • The overall cold gas efficiency is found to be 58.35 %. • The high-temperature electrolysis cell consumes 75 % of input electricity. • Decreasing input water of electrolyzer enhances efficiency and CO 2 utilization. [ABSTRACT FROM AUTHOR]

Offshore wind power integration is a grand challenge due to the volatility, randomness and intermittency This work presents a wind-thermal-electrolysis-battery (WTEB) hybrid energy system designed to integrate large-scale offshore wind energy and reduce curtailment. The system composes of offshore wind farms (OWF), thermal power plants (TPP), electrolysis station, battery bank. The Qingzhou (geographic name) I-VII offshore wind farms (5000 MW) and the Yangxi (geographic name) coal-fired power plant units #5, #6 (2 × 1240 MW) are taken as a case study. The OWF is the indispensable generator and the renewable fraction increases with integration level. The TPP adjusts the load ratio to meet the changing net load. The electrolysis station consumes the excess electricity and the battery bank time-shifts the electricity to reduce the electrolyzer downtime. The recommended wind-thermal (W-T) capacity ratio is 1.452:1 in the studied case, namely 3600 MW OWF. The WTEB system breaks the trade-off relationship between renewable fraction (50.11%) and curtailment rate (1.48%) compared to traditional wind-thermal (WT) bundled system. The WPEB system improves the electricity shortage rate (4.74%), transmission line capacity factor (61.79%), load following precision (91.79%). The internal rate of return (IRR), levelized cost of electricity (LCOE), levelized cost of hydrogen (LCOH) of WTEB-W3600 are 34.70%, 0.5172 ¥/kWh, 29.76 ¥/kg. The WTEB hybrid energy system for a large-scale offshore wind power integration is first proposed and the techno-economic feasibility analysis proves the feasibility and forward-looking of the system. Collaborative capacity optimization of OWF, TPP, electrolysis station, battery can improve the system performance and economy. The wind-photovoltaic-thermal-electrolysis-battery (WPTEB) system co-locating the OWF and floating photovoltaic (PV) is an important development direction. Figure. Schematic of the wind-thermal-electrolysis-battery (WTEB) hybrid energy system in Yangjiang, China. [Display omitted] • WTEB enables a large-scale offshore wind power integration and curtailment reduction. • WTEB improves load following precision, electricity shortage and curtailment rate. • The wind-thermal (W-T) capacity ratio of the WTEB system is 1.452:1. • The electrolyzers and battery bank operate on the curtailed electricity. • The NPV, LCOE, IRR of WTEB-W3600 are 3.13 billion¥, 0.5172 ¥/kWh, 4.70%. [ABSTRACT FROM AUTHOR]

Fuel synthesis through CO 2 hydrogenation is receiving much attention to decarbonizing the transport sector of future energy systems. In this study, an integrated system is proposed and investigated from a thermo-economic point of view to produce power and synthetic methane and methanol. The proposed system includes an externally fired gas turbine, Rankine cycle, organic Rankine cycle, proton exchange membrane electrolyzer, molten carbonate fuel cell and methane and methanol synthesis units. CO 2 hydrogenated under three different scenarios to produce methane-only, methanol-only and dual-production assuming various operating loads of electrolyzer. The influence of the key parameters on the system performance is assessed via response surface method and finally, the system performance is optimized. Under the base conditions, overall exergy efficiency, levelized cost of electricity, methanol and methane is estimated to be 36.8 %, 37.6, 92.8 and 79.4 $/MWh, respectively. Under the optimized conditions for the methane-only scenario, the overall exergy efficiency, levelized cost of electricity and methane is found to be 34.8 %, 36.7 $/MWh and 77.3 $/MWh, respectively. • A biomass-driven system is investigated to produce power and synthetic fuel. • Captured CO 2 via molten carbonate fuel cell is hydrogenated to produce synthetic fuel. • Three different scenarios are evaluated: producing methane, methanol and both. • Multi-objective optimization is conducted. • Minimum cost of electricity and methane is 36.7 and 77.3 $/MWh, respectively. [ABSTRACT FROM AUTHOR]

Estimates on the costs of renewable energy supply by hydrogen and hydrogen-based derivatives such as ammonia or organic compounds (e.g., synthetic methane, methanol, Fischer-Tropsch fuels) vary substantially among current publications. Hence, comprehensive analyses of each stage of the renewable energy supply chain are necessary, with ship transportation as the focus of this work. Shipping cost projections for various hydrogen-based derivatives from a wide range of recent international publications are compared, identifying uncertainties and research gaps in the shipping of Power-to-X energy carriers. While transportation costs in literature reveal a consistent picture for liquid ammonia, projections for liquid hydrogen, LOHCs, and, surprisingly, also for methanol, Fischer-Tropsch fuels and liquid methane differ significantly. Technological and economic assumptions contributing to the discrepancies are discussed. A sensitivity analysis is provided to quantify the effects of divergent assumptions for different parameters on shipping costs. • Projections of future ammonia shipping costs are quite consistent. • Cost projections for hydrogen diverge as large-scale shipping is not established. • Cost projections for hydrocarbon energy carriers reveal significant inconsistencies. • Discrepancies mainly attribute to ship's speed, lifetime and CAPEX assumptions. [ABSTRACT FROM AUTHOR]

The integration of offshore wind energy into Power‐to‐X (PtX) process chains offers opportunities for the efficient use of renewable energy. This article analyzes different PtX process chain configurations and their adaptation to the offshore environment. However, direct coupling of PtX platforms with fluctuating electrical energy poses major challenges. Dynamic process simulation is presented for analysis of different plant configurations and operating strategies. The article emphasizes the need for interdisciplinary research to consider technological as well as economic and environmental aspects. [ABSTRACT FROM AUTHOR]

Green hydrogen and power-to-X technologies hold significant potential in the global energy transition towards net-zero emissions. This is attributed to the premise that these technologies can decarbonize numerous sectors worldwide by providing versatile and sustainable energy carriers and industrial feedstocks to replace fossil-based fuels and chemicals. To this end, the qualitative benefits of green hydrogen and power-to-X technologies have been thoroughly examined for various applications in past years. In contrast, quantifying the potential penetration of such technologies on national and global levels still requires extensive research. Therefore, this paper investigates the prospective integration of green hydrogen and power-to-X technologies within Jordanian industries, considering their quantitative utilization potential for current and future capacities. The findings showed that the Jordanian food processing and heavy industries emerged as major sectors with substantial potential for incorporating green hydrogen and power-to-X products as alternative fuels or chemical feedstocks. In detail, the total potential utilization capacity for these sectors stood at around 57 thousand tons per year. Specifically, fertilizers production, cement industry, steel reforming, and oil refinery possess an annual potential capacity of around 6.8, 11.8, 12.7, and 25.8 thousand tons, respectively. It is also worth mentioning that the current utilization capacity of hydrogen in Jordanian industries was found to be around 8.9 thousand tons per annum, which is completely covered by fossil-based hydrogen to date. These results imply that there will be a promising market for green hydrogen and power-to-X utilization in Jordanian industries, which will play a significant role in integrated energy transition efforts in the future. [ABSTRACT FROM AUTHOR]

Green hydrogen and synthetic fuels are increasingly recognized as a key strategic element for the progress of the global energy transition. The Middle East and North Africa (MENA) region, with its large wind and solar potential, is well positioned to generate renewable energy at low cost for the production of green hydrogen and synthetic fuels, and is therefore considered as a potential future producer and exporter. Yet, while solar and wind energy potentials are essential, other factors are expected to play an equally important role for the development of green hydrogen and synthetic fuels (export) sectors. This includes, in particular, adequate industrial capacities and infrastructures. These preconditions vary from country to country, and while they have been often mentioned in the discussion on green hydrogen exports, they have only been examined to a limited extent. This paper employs a case study approach to assess the existing infrastructural and industrial conditions in Jordan, Morocco, and Oman for the development of a green hydrogen and downstream synthetic fuel (export) sector. [ABSTRACT FROM AUTHOR]

This paper investigates the project implementation of e-fuel production in Denmark to compare two projects and execute interviews with project employees, experts within the e-fuel field and authorities both local and national. A SWOT analysis of the interview outcomes was conducted as well as an internal and external factor evaluation. The analyses highlight the internal and external project factors that impact the implementation of these projects in Denmark. The analysis showed that collaboration and engagement of stakeholders, citizens and authorities to a large extent can mitigate hindrances and drive the projects forward in development. Large interest in these projects from all sides of the project implementation and development is a part of this. A threat to the implementation is the uncertain and rigid regulatory framework that involves permitting processes and conditions such as tax reductions. This threat can to a large extent be aided by the collaboration with stakeholders. The regulatory framework is not fit to the novelty of these cases which poses new requirements to the framework. Market readiness and offtake agreements pose obstacles for the projects, which are both external and internal conditions of the projects. The topic of the amount of renewable electricity in the grid is discussed among the interviewees and shows a discrepancy on whether or not this is an issue for the projects. However, it seems to be an issue only for projects that are expected to be in commission before 2028 where the electricity in the grid is not generated by renewable energy only. [ABSTRACT FROM AUTHOR]

A rapid defossilisation of the industry sector is required to stop further greenhouse gas emissions and to curb global warming. Additionally, to avoid irreversible consequences caused by climate change, the deployment of negative emission technologies is required to reduce the carbon dioxide (CO2) concentration in Earth’s atmosphere to a sustainable level. A novel approach to store gaseous CO2 from direct air capture facilities in solid silicon carbide (SiC) is presented. A chain of established processes to produce SiC from renewable electricity and air is evaluated in terms of energy and mass balances. Furthermore, possible fields of SiC utilisation are considered. Electricity-based SiC (e-SiC) can serve the growing global market for technical ceramics and can possibly be used to tackle increasing construction sand shortages in the construction industry by partially substituting sand. Calculations of the levelised cost of carbon dioxide removal show that storing ambient CO2 in solid SiC that can be subsequently sold on the world market can eventually create profit. In 2050, a net benefit of 259 €/tCO2 or 631 €/tSiC can be realised if the SiC product is sold at the world market with additional carbon compensation. Therefore, the proposed SiC production chain might be able to challenge conventionally produced SiC, while empowering negative emissions. In 2050, the net CO2 emission potential is limited to about 290 MtCO2/a for technical ceramics, but may reach up to 13.6 GtCO2/a for construction sand. Results show that e-SiC production is economically feasible for technical ceramics but not for construction sand without further process cost decrease. Alternative processes to produce e-SiC are described and evaluated. Future research opportunities are discussed. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the waste streams from the production of hydrogen energy carriers from PtX technology and identify how they can be valorized by applying a symbiotic approach to enable greater utilization of the inputs and outputs from such plants. Various electrolysis development projects are under development or in the pipeline in Europe and Denmark, but in many cases, it is not clear how waste streams are emphasized and valued in these projects. Thus, three exploratory case studies (a city, a rural, and an energy hub case) were investigated herein exemplifying state-of-the-art electrolysis projects currently being deployed, with a focus on identifying how and to what extent waste streams are being valorized in these projects and energy system integration is being pursued. Inspired by the industrial symbiosis literature, we analyzed how internal, regional, and long-distance symbiotic collaboration is realized within these cases and found them to be very different in terms of the energy carrier produced, the current development stage, and the access to appropriate energy infrastructure. This paper concludes that the co-location of PtX technology near biogas plants would provide a great opportunity for the integration of the produced energy carriers and waste streams into the existing energy system and, hence, could assist in stabilizing fluctuating renewable energy sources to enable their more efficient use in the energy system. [ABSTRACT FROM AUTHOR]

Copyright of Nachhaltigkeitsrecht is the property of Verlag Oesterreich GmbH and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The objective of this paper is to review the academic literature and identify best practices on the integration of artificial intelligence and sustainable technologies in strategic renewable energy and Power-to-X projects globally. We reflect upon the way in which exemplary case studies can be used to foster a common shared view among different policy makers to highlight new ways through which energy efficiency and systemic improvements in the energy sector may be achieved while curbing carbon emissions and addressing climate change. The main risks, challenges and mitigations for integrating artificial intelligence and sustainable technologies in energy systems are also educed from both the academic literature as well as interviews with experts. Our findings indicate that while the integration of artificial intelligence and sustainable technologies can support energy efficiency and systemic improvements in the energy sector, there are several risks that were not previously identified in the literature. Critical areas of future development for academic research as well as opportunities for professional practice are presented. [ABSTRACT FROM AUTHOR]

The fight against global warming requires novel approaches for the defossilisation of industrial processes, and the limitation of global warming requires options for negative carbon dioxide (CO2) emissions. The production of carbon fibre (CF) is an energy-intensive chain of processes which cause CO2 emissions. Having in mind the high market growth for CF composite materials, CF production might stand against the fight against global warming. CF also offers a huge mitigation opportunity, as CF contain up to 95–98wt% of pure carbon. This study investigates possible ways to link CF production to atmospheric CO2, enabling negative CO2 emissions through CF manufacturing. Production value chains for CF based on poly(acrylonitrile) (PAN) and pitch, the two most important CF precursor materials, are developed and analysed regarding their energy and mass balances. The PAN value chain is further assessed regarding a first economic estimation of CF production cost with atmospheric CO2 as carbon source. The results show that production costs per ton CO2 removed might be unattractive at 2949 €/tCO2 in 2050. However, from a CF perspective, production cost of 10.3 €/kgCF in 2050 might enable a business case for electricity-based CF production from atmospheric CO2 in the future. Each ton of CF produced can store about 3.5 tCO2 due to a very high carbon share in the final product. With an increasing market for CF, a total negative emission potential of at least 0.7 GtCO2 per year can be enabled by 2050. Further research opportunities are discussed. [ABSTRACT FROM AUTHOR]

The increased share of variable renewable energy sources such as wind and solar power poses constraints on the stability of the grid and the security of supply due to the imbalance between electricity production and demand. Chemical storage or power-to-X technologies can provide the flexibility that is needed to overcome this issue. To quantify the needs of such storage systems, energy system optimization models (ESOMs) are used, guiding policy makers in nationwide energy planning. The key input parameters for such models are the capacity and efficiency values of the conversion devices. Gas turbines, reciprocating engines, fuel cells and Rankine engines are often mentioned here as cogeneration technologies. Their performance parameters will however need to be revised when switching from fossil to renewable fuels. This study therefore investigates the possibility of using size-based scaling laws to predict the efficiency and power values of one type of conversion technology: the reciprocating engine. The most straightforward scaling laws are the ones based on the fundamental engine performance parameters and are constructed by fitting an arithmetic function for a large set of representative engine data. Their accuracy was tested with a case study, consisting of thirty large-bore, spark-ignited gas engines. Two alternative methods were also investigated: scaling laws based on the Willans line method and scaling laws based on the similarity theory. Their use is deemed impractical for the current research problem. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive techno-economic analysis of different energy storage systems (ESSs) in providing low-voltage ride-through (LVRT) support for power electronics-based electrolyzer systems. A framework for analyzing the performance of a grid-integrated electrolyzer-ESS system is developed, taking into account realistic scenarios and accurate models. The system components consist of a 500 kW alkaline electrolyzer module integrated with a medium-voltage grid and three different commercially available ESSs based on Li-ion battery, Li-ion capacitor, and supercapacitor technology, respectively. The performance of these ESSs is extensively studied for three LVRT profiles, with a primary focus on the upcoming Danish grid code. In order to perform simulation studies, the system is implemented on the MATLAB®/Simulink®-PLECS® platform. The results demonstrate that all three energy storage technologies are capable of supporting the electrolyzer systems during low-voltage abnormalities in the distribution grid. The study also reveals that the supercapacitor-based technology seems to be more appropriate, from a techno-economic perspective, for fault ride-through (FRT) compliance. [ABSTRACT FROM AUTHOR]

Renewable methanol has potential to be a key vector for attaining net zero emissions by providing a pathway to carbon neutrality for the value chains of carbon intensive industries with hard to abate emissions. To deliver an accurate assessment of feasibility, it is critical to understand the integrated operation and economies of the connected generation and conversion technologies that make up Power-to-Methanol (PtM) pathways. Given the highly variable nature of renewable energy (RE) and green hydrogen generation, it is also important to consider the need for feedstock and energy buffers to achieve reliable operation. Herein, we developed a globally applicable open-source cost framework consisting of a farm-to-gate model of Power-to-Methanol (PtM) populated with performance and cost functions from process simulation, recent literature, and industry consultation. This open-source tool was developed to evaluate PtM projects at various scales and locations, utilizing different recycled carbon feedstock sources, with a range of renewable power generation and electrolyser configurations, as well as balancing technologies including intermediate feedstock and power storage options. A key feature of the tool is the ability to analyse and optimize the incorporation of these balancing technologies. By using present cost estimates and defining design constraints to maintain operational viability, we apply this framework to map out the economies of PtM for potentially suitable Australian and international locations as case studies. The study estimates indicative levelized cost of methanol (LC MeOH) of 1360 A$/t MeOH and 1710 A$/t MeOH corresponding to PtM including CO 2 sourced from industrial flue gas (IFG) and direct air capture (DAC) respectively. While the case studies analysed in this work consist mainly of Australian locations, the open-source tool is applicable for other global locations as demonstrated by the cases evaluated for PtM in Chile and Germany. The tool presented here aims to serve as a customisable framework to support the assessment, optimization, and deployment of commercial scale e-methanol projects. • Open-source cost tool for assessment of economic viability of e-methanol projects. • Visualize local methanol generation based on time series renewable trace data. • Define custom costing and operational parameters for tailored generation costs. • Assess the impact of renewable intermittency to optimize configuration performance. • Estimate farm-to-gate and farm-to-grave direct and embedded emissions. [ABSTRACT FROM AUTHOR]

Aiming to advance the technical maturity of CO2 electrolysis to formic acid, various gas diffusion layers (GDLs) are investigated for their suitability as carbon‐based substrate for gas diffusion electrodes (GDEs) and their effect on the electroreduction of CO2 to formate. Particular attention lies on the elucidation for the effect of the GDL thickness, hydrophobic treatment, and presence of a microporous layer (MPL) on the GDE performance in terms of Faradaic efficiency. Based on the investigation it is found that the GDL thickness has no discernible influence on the Faradaic efficiency, while a GDE with a hydrophobic treatment of 10 % PTFE outperforms a GDE based on a GDL with 30 % PTFE. Furthermore, the presence of a MPL is found to be of marked importance to achieve relevant current densities given its effect on the focus of the catalyst layer on the GDE surface after spray coating, the wetting, and the electrical conductivity. [ABSTRACT FROM AUTHOR]

The challenges posed by climate change have prompted significant growth in efficiency evaluation and optimization research, especially in recent years. This has spawned a variety of heterogeneous methods and approaches to the assessment of technical processes. These methods and approaches are rarely comparable and are usually only applicable to specific sectors. This paper provides an overview of the literature on efficiency assessment methods and KPIs, leading to a more manageable selection of an appropriate method with special regard to energy system integration technologies. In addition to reviewing the literature systematically, this paper examines existing methods and indicators’ applicability to and significance for efficiency optimization. In this context, a holistic approach to process design, evaluation, and improvement is given with particular regard to power-to-X systems. Within the framework of the study, three overarching goals could be defined as levels of efficiency evaluation of power-to-X systems: 1. identification of the process (steps) with the most significant optimization potential, 2. identification of the process phases with the greatest optimization potential (timewise considered), and 3. derivation of specific recommendations for action for the improvement of a process. For each of these levels, the most suitable evaluation methods were identified. While various methods, such as life cycle assessment and physical optimum, are particularly suitable for Level 1 and Level 2, for Level 3, even the best-identified methods have to be extended on a case-by-case basis. To address this challenge, a new approach to a holistic evaluation of power-to-X systems was developed based on the study’s findings.

For achieving a carbon–neutral energy system, economical flexibility mechanisms are crucial to accommodate intermittent and decentralized renewable energy sources. Power-to-X (P2X) is a promising technology for this purpose. This study aims to elucidate the systematic effects and competition of dynamically operated power-to-X (P2X) technologies as a flexibility option in comprehensive renewable energy systems. We developed a linear programming model to optimize energy systems incorporating P2X technologies, including water electrolysis, methanation, Fischer–Tropsch synthesis, and Haber–Bosch synthesis, and investigated the impact of P2X flexibility on the system structure and energy costs, focusing on Japan as a case study. The results demonstrate that each P2X technology effectively shifts electricity loads and reduces curtailment by more than 80%. The contribution of each P2X technology varies, with water electrolysis playing a dominant role due to its relatively low fixed costs and large scale. Furthermore, the mechanism significantly reduces system costs by 35% and supply costs of electricity and hydrogen by 41% and 30%, respectively, by reducing the required capacities of electricity generators, stationary batteries, and transmission grids. Therefore, P2X has a cost advantage over these flexibility options. The results also highlight that the maximum effect is achieved when the capacity factor of P2X is 30%. However, synthetic hydrocarbons would require a carbon price of over 356 EUR/tCO2 to compete with fossil fuels. Domestic electrofuels would face tough competition with global fuel costs. Nevertheless, the reduction in electricity costs through P2X, along with its contribution to energy security, may incentivize its adoption.

This study proposes a country-based life-cycle assessment (LCA) of several conversion pathways related to both on grid-connected Power-to-X (PtX) fuels and advanced biofuel production for maritime transport in Europe. We estimate the biomass resource availability (both agricultural and forest residues and second-generation energy crops from abandoned cropland), electricity mix, and a future-oriented prospective LCA to assess how future climate change mitigation policies influence the results. Our results indicate that the potential of PtX fuels to achieve well-to-wake greenhouse gas intensities lower than those of fossil fuels is limited to countries with a carbon intensity of the electricity mix below 100 gCO2eq kWh−1. The more ambitious FuelEU Maritime goal could be achieved with PtX only if connected to electricity sources below ca. 17 gCO2eq kWh−1 which can become possible for most of the national electricity mixes in Europe by 2050 if renewable energy sources will become deployed at large scales. For drop-in and hydrogen-based biofuels, biomass residues have a higher potential to reduce emissions than dedicated energy crops. In Europe, the potentials of energy supply from all renewable and low-carbon fuels (RLFs) range from 32 to 149% of the current annual fuel consumption in European maritime transport. The full deployment of RLFs with carbon capture and storage technologies could mitigate up to 184% of the current well-to-wake shipping emissions in Europe. Overall, our study highlights how the strategic use of both hydrogen-based biofuels and PtX fuels can contribute to the climate mitigation targets for present and future scenarios of European maritime transport.

The Paris Agreement targets to halt the progression of climate change necessitate global cooperation and renewable energy uptake in developed and developing countries at similar rates. This study explores the energy transition pathway options for Egypt across the power, heat, transport, and desalination sectors as a representative case study for other emerging sunbelt economies. The LUT Energy System Transition Model has been used to investigate the feasibility of six scenarios, including four variations of best policy, delayed policy, and current policy scenarios. The least-cost solution, achieving 100% renewable energy and zero CO 2 emissions by 2050, is dominated by solar photovoltaics at 90% of the total primary energy demand. Key transition enablers are the excellent and low-cost solar resources, energy storage, and Power-to-X technologies allowing high electrification and full sector coupling. The results reveal that the current and delayed policy scenarios are the most expensive pathways, highlighting the value of leapfrogging into a fully renewable system. Such a transition would require policy reforms that balance investment risks in emerging economies and enable its financial mobilisation. The structural results of this study provide a reliable guide for energy transition planning in Egypt as well as other emerging sunbelt economies. [ABSTRACT FROM AUTHOR]

Unprecedented increase in atmospheric CO2 levels calls for efficient, sustainable, and cost‐effective technologies for CO2 removal, including both capture and conversion approaches. Current CO2 abatement is largely based on energy‐intensive thermal processes with a high degree of inflexibility. In this Perspective, it is argued that future CO2 technologies will follow the general societal trend towards electrified systems. This transition is largely promoted by decreasing electricity prices, continuous expansion of renewable energy infrastructure, and breakthroughs in carbon electrotechnologies, such as electrochemically modulated amine regeneration, redox‐active quinones and other species, and microbial electrosynthesis. In addition, new initiatives make electrochemical carbon capture an integrated part of Power‐to‐X applications, for example, by linking it to H2 production. Selected electrochemical technologies crucial for a future sustainable society are reviewed. However, significant further development of these technologies within the next decade is needed, to meet the ambitious climate goals. [ABSTRACT FROM AUTHOR]

Combining Power‐to‐X (PtX) processes with high temperature heat pumps (HTHP) can significantly increase their energy efficiency. Evaluating the example of oxymethylene ethers (OME) production from H2 via H2O electrolysis and captured CO2 from air shows that by upgrading waste heat streams using HTHP, a process overall energy efficiency of higher than 61 % can be achieved compared to 30 % in conventional integrated processes. Thereby, the waste heat stream from H2O electrolysis already covers the low temperature heat demand for CO2 capture via direct air capture, not only for OME but also for various PtX products. Importantly, a significant lever for the energy efficiency enhancement is the consideration of other low temperature heat‐demanding sectors. High overall process energy efficiencies and the electrification of the industry are key aspects towards a sustainable mobility sector. [ABSTRACT FROM AUTHOR]

Abstract Aiming to advance the technical maturity of CO2 electrolysis to formic acid, various gas diffusion layers (GDLs) are investigated for their suitability as carbon‐based substrate for gas diffusion electrodes (GDEs) and their effect on the electroreduction of CO2 to formate. Particular attention lies on the elucidation for the effect of the GDL thickness, hydrophobic treatment, and presence of a microporous layer (MPL) on the GDE performance in terms of Faradaic efficiency. Based on the investigation it is found that the GDL thickness has no discernible influence on the Faradaic efficiency, while a GDE with a hydrophobic treatment of 10 % PTFE outperforms a GDE based on a GDL with 30 % PTFE. Furthermore, the presence of a MPL is found to be of marked importance to achieve relevant current densities given its effect on the focus of the catalyst layer on the GDE surface after spray coating, the wetting, and the electrical conductivity.

One of the biggest global challenges we are facing today is the provision of affordable, green, and sustainable energy to a growing population. Enshrined in multiple United Nation Sustainable Development Goals – Goal 7: Affordable and Clean Energy; Goal 11: Sustainable Cities and Communities; Goal 12: Responsible Consumption and Production and Goal 13: Climate Action – as well as at the core of the Paris Agreement, it is our task as scientists and engineers to develop innovative technologies that satisfy society's needs while pivoting away from the use of fossil resources. This is a mammoth task with an ambitious timeline. The global development of the industrial sector as we know it is solely based on the exploitation of energy-rich fossil fuels that remain cost-competitive today. However, a gradual change from a market driven to a policy-driven transition allows alternative technologies to make inroads and find applications. One of the most prominently discussed approaches is the Power-to-X (PtX) process envelope. It describes a series of catalytic conversions using only renewable energy, water and captured CO2 to produce green hydrogen, liquid hydrocarbon fuels and chemicals. Especially for sectors that are difficult or impossible to decarbonise, such processes that effectively defossilising the production of energy and goods, represent an important solution.The Catalysis Institute at the University of Cape Town (herein/after referred to as the Catalysis Institute) builds on decades of experience in the individual catalytic processes combined in the PtX concept. In collaboration with our global partners, we are therefore able to develop technologies for the full value chain, considering interdependencies and develop solutions for the African and indeed global society.

This paper analyzes the operation of an energy hub on a community level with an integrated P2X facility and with access to energy markets. In our case, P2X allows converting power to hydrogen, heat, methane, or back to power. We consider the energy hub as a large prosumer who can be both a producer and consumer in the markets with the novelty that P2X technology is available. We investigate how such a P2X energy hub trades optimally in the electricity market and satisfies local energy demand under the assumption of a long-term strong climate scenario in year 2050. For numerical analysis, a case study of a mountain village in Switzerland is used. One of the main contributions of this paper is to quantify key conditions for profitable operations of such a P2X energy hub. In particular, the analysis includes impacts of influencing factors on profits and operational patterns in terms of different degrees of self-sufficiency and different availability of local renewable resources. Moreover, the access to real-time wholesale market electricity price signals and a future retail hydrogen market is assessed. The key factors for the successful operation of a P2X energy hub are identified to be sufficient local renewable resources and access to a retail market of hydrogen. The results also show that the P2X operation leads to an increased deployment of local renewables, especially in the case of low initial deployment; on the other hand, seasonal storage plays a subordinated role. Additionally, P2X lowers for the community the wholesale electricity market trading volumes.

The EU is promoting hydrogen as enabling energy carrier that may account for up to 20% of energy and especially fulfill between 20% and 50% of transportation demands and between 5% and 20% of industrial needs. To ensure the success of this shift, Power-to-Hydrogen and Hydrogen-to-X technologies have attracted significant interest because they transform renewable power directly into green hydrogen, via water electrolysis, which can be stored and transferred more readily than other fuels for several end-uses. The present paper aims to discuss the role of such technologies in the current and future energy systems, with a specific reference to the European scenario. The main energy sectors where hydrogen could play an important role will be discussed, such as transportation, power generation, manufacturing sectors, refining and agriculture, with a focus on potential technological integration and synergies, providing a guideline for industrial players up to 2050 with a discussion about technology maturity by presenting short-term/long-term roadmaps. [Display omitted] • Overview of green hydrogen production and Power-to-Hydrogen concepts. • Focus on European hydrogen demand and potential hydrogen applications. • Overview of several concepts of Hydrogen-to-X, enabling sector coupling. • Hydrogen can store energy with capacities ranging from 1 MW to 10 GW. • Hydrogen has the potential to meet 5–20% of industrial energy needs. [ABSTRACT FROM AUTHOR]

Hydrogen as an energy vector is seen as a key for the energy transition. Recently, more than 30 countries have launched their hydrogen strategies and roadmaps. Hydrogen storage and transportation are challenging steps of the hydrogen economy since all available options have significant drawbacks. This paper evaluates a power-to-liquid hydrogen process; the system is "charged" with electricity from renewable sources to produce hydrogen via water electrolysis; the produced hydrogen gas is liquefied and stored at ambient pressure and cryogenic temperature. The purpose of this paper is to report the first evaluation results of a system including a polymer electrolyte membrane electrolyser and a hydrogen liquefier. The evaluation was conducted using exergy-based methods, i.e. exergetic, exergoeconomic and exergoenvironmental analyses. The process of hydrogen liquefaction was simulated with the aid of the Aspen Plus software. The exergetic efficiencies for the liquefaction process and for the electrolyser are 42% and 47%, respectively. While the total exergetic efficiency of the power-to-liquid hydrogen system amounts to 44%. The total exergy destruction for the liquefier amounts to 9.3 MW and for the polymer electrolyser membrane electrolyser amounts to 19.3 MW. The electrolyser followed by the hydrogen compressors were identified as the components with the highest exergy destruction values and investment costs, while the compressors and the recuperators account for the highest exergoenvironmental impact. The sensitivity analysis shows that the specific liquefaction cost of hydrogen strongly varies with the electricity price and the cost of green hydrogen. • Green liquid hydrogen energy storage as a "power-to-liquid" approach is discussed. • The possibility of improvement of a hydrogen liquefaction system is assessed. • Exergy-based methods are used to identify the inefficiencies within the system. • The most important components from the thermodynamic, economic and environmental viewpoints are identified. [ABSTRACT FROM AUTHOR]

The era of considering carbon dioxide (CO2) as a waste stream has passed. New methods of utilising CO2 as a carbon feedstock are currently the focus of extensive research efforts. A fixed-bed reactor containing a commercial Cu/ZnO/Al2O3 catalyst washcoated on a Cu foam was used for the synthesis of methanol through direct CO2 hydrogenation. Catalytic activity tests in this reactor were conducted at reaction pressures of 30 and 50 bar, temperatures in the range 190–250 °C, and weight hourly space velocities (WHSV) in the range 1.125–2.925 NL gcat−1 h−1. The best reactor performance was recorded at 50 bar pressure: CO2 conversion and methanol selectivity of 27.46% and 82.97%, respectively, were obtained at 240 °C and 1.125 NL gcat−1 h−1. Increasing the WHSV to 2.925 NL gcat−1 h−1 resulted in a twofold increase in methanol weight time yield (WTY) to 0.18 gMeOH gcat−1 h−1 and a decrease in methanol selectivity to 70.55%. The results presented in this investigation provide insight into the performance of a bench-scale reactor in which mass transfer limitations are non-negligible and demonstrate that metal foams are promising catalyst support structures for CO2 hydrogenation towards methanol production. [ABSTRACT FROM AUTHOR]

The electrochemical conversion of NOx (including NO3– and NO2–) to ammonium using renewable energy is emerging as a green alternative pathway for decarbonization of high emission industry to meet net zero emission targets. The key to efficient NOx electrolysis relies on the understanding of surface chemistry to establish the structure–activity relationships that will govern future scaleup of this process. In this work, we have undertaken a mechanistic investigation, wherein by tuning the surface oxidation state of CuOx nanoparticles on Cu foam (referred as CuOx/CuF), we are able to investigate its impact on conversion of NOx to ammonium (NH4+) under acidic reaction conditions. Supported by in situ Raman measurements, we reveal the importance of tuning the Cu oxidation state to maximize Cu2O formation, which forms beneficial Cu2O/Cu interfaces during reaction, allowing an enhanced NH4+ yield with a production rate of 45 nmol s–1 cm–2 and Faradaic efficiency (FENH4+) of 83% at −0.5 V vs RHE. Further, we reveal the promising stability of such interfaces under acidic conditions during long-term electrolysis for usage of up to 20 h. [ABSTRACT FROM AUTHOR]

Power-to-X (P2X) technologies will play a more important role in the conversion of electric power to storable energy carriers, commodity chemicals and even food and feed. Among the different P2X technologies, microbial components form cornerstones of individual process steps. This review comprehensively presents the state-of-the-art of different P2X technologies from a microbiological standpoint. We are focusing on microbial conversions of hydrogen from water electrolysis to methane, other chemicals and proteins. We present the microbial toolbox needed to gain access to these products of interest, assess its current status and research needs, and discuss potential future developments that are needed to turn todays P2X concepts into tomorrow's technologies. [ABSTRACT FROM AUTHOR]

Using hydrogen (H2) and ammonia (NH3) for renewable energy storage has the potential to enable economical power and heat supply with high renewable penetrations, especially in remote locations which are characterized by high energy costs. In this work we assess the economic competitiveness of renewable combined heat and power (CHP) systems in Mahaka HI, Nantucket MA, and Northwest Arctic Borough (NWAB) AK by optimally designing these systems for scenarios in which power and heat can be purchased over a range of historical energy prices as well as when 100% renewable supply is required. We use a combined optimal design and scheduling model which minimizes annualized net present cost by determining optimal technology selection and size simultaneously with optimal schedules for each period of a system operating horizon aggregated from full year hourly resolution data via a consecutive temporal clustering algorithm. We find that renewable generation meets at least 85% of power demands and 75% of heat demands under the lowest energy prices investigated. Higher conventional energy prices lead to increased renewable penetration which is facilitated by renewable NH3 as a seasonal energy storage medium, as are 100% renewable CHP systems. NH3 is used for power generation with heat cogeneration in all three locations, as well as directly for heating in NWAB. On an annual cost basis, NH3‐enabled 100% renewable CHP is only 3% more expensive in Mahaka and NWAB than systems which can purchase energy at the lowest prices, while it is 15% more expensive in Nantucket. [ABSTRACT FROM AUTHOR]

The challenges posed by climate change have prompted significant growth in efficiency evaluation and optimization research, especially in recent years. This has spawned a variety of heterogeneous methods and approaches to the assessment of technical processes. These methods and approaches are rarely comparable and are usually only applicable to specific sectors. This paper provides an overview of the literature on efficiency assessment methods and KPIs, leading to a more manageable selection of an appropriate method with special regard to energy system integration technologies. In addition to reviewing the literature systematically, this paper examines existing methods and indicators' applicability to and significance for efficiency optimization. In this context, a holistic approach to process design, evaluation, and improvement is given with particular regard to power-to-X systems. Within the framework of the study, three overarching goals could be defined as levels of efficiency evaluation of power-to-X systems: 1. identification of the process (steps) with the most significant optimization potential, 2. identification of the process phases with the greatest optimization potential (timewise considered), and 3. derivation of specific recommendations for action for the improvement of a process. For each of these levels, the most suitable evaluation methods were identified. While various methods, such as life cycle assessment and physical optimum, are particularly suitable for Level 1 and Level 2, for Level 3, even the best-identified methods have to be extended on a case-by-case basis. To address this challenge, a new approach to a holistic evaluation of power-to-X systems was developed based on the study's findings. [ABSTRACT FROM AUTHOR]

Power-to-X is one of the most attention-grabbing topics in the energy sector. Researchers are exploring the potential of harnessing power from renewable technologies and converting it into fuels used in various industries and the transportation sector. With the current market and research emphasis on Power-to-X and the accompanying substantial investments, a review of Power-to-X is becoming essential. Optimization will be a crucial aspect of managing an energy portfolio that includes Power-to-X and electrolysis systems, as the electrolyzer can participate in multiple markets. Based on the current literature and published reviews, none of them adequately showcase the state-of-the-art optimization algorithms for energy portfolios focusing on Power-to-X. Therefore, this paper provides an in-depth review of the optimization algorithms applied to energy portfolios with a specific emphasis on Power-to-X, aiming to uncover the current state-of-the-art in the field. [ABSTRACT FROM AUTHOR]

There are increasing international efforts to tackle climate change by reducing the emission of greenhouse gases. As such, the use of electrolytic hydrogen as an energy carrier in decentralised and centralised energy systems, and as a secondary energy carrier for a variety of applications, is projected to grow. Required green hydrogen can be obtained via water electrolysis using the surplus of renewable energy during low electricity demand periods. Electrolysis systems with alkaline and polymer electrolyte membrane (PEM) technology are commercially available in different performance classes. The less mature solid oxide electrolysis cell (SOEC) promises higher efficiencies, as well as co-electrolysis and reversibility functions. This work uses a bottom-up approach to develop a viable business model for a SOEC-based venture. The broader electrolysis market is analysed first, including conventional and emerging market segments. A further opportunity analysis ranks these segments in terms of business attractiveness. Subsequently, the current state and structure of the global electrolyser industry are reviewed, and a ten-year outlook is provided. Key industry players are identified and profiled, after which the major industry and competitor trends are summarised. Based on the outcomes of the previous assessments, a favourable business case is generated and used to develop the business model proposal. The main findings suggest that grid services are the most attractive business sector, followed by refineries and power-to-liquid processes. SOEC technology is particularly promising due to its co-electrolysis capabilities within the methanol production process. Consequently, an “engineering firm and operator” business model for a power-to-methanol plant is considered the most viable option.

This study focuses on harnessing excess heat from Power-to-X technologies in future energy hubs. By coupling thermodynamics with an optimization model, a novel analysis is performed using the Greenlab Skive energy hub, which includes hydrogen and methanol synthesizers, as a case study. Pinch analysis techniques are employed to design a heat exchanger network that can thermally integrate processes within the energy hub. Through the EnerHub2X modelling framework, three scenarios are optimized to explore and compare the potential of excess heat recovery. Excess heat is utilized through an optimally designed heat exchanger network, which achieves up to 3.49 MW of heat recovery. This leads to increased profits due to reduced natural gas costs and higher methanol sales. Upgrading excess heat and distributing it to the district heating network yields the highest profit, driven by increased compressed hydrogen and methanol production and the sale of heat to district heating. Thermal integration reduces waste heat by 14.5%, while utilizing excess heat in the district heating network results in 60% further reduction. An economic assessment confirms the feasibility and profitability of the project. Sensitivity analyses are undertaken to analyse the impact of critical parameters on the model, such as electricity and heat prices, along with the selling prices of methanol and hydrogen. The results highlight that excess heat utilization enhances profitability, energy efficiency, and sustainability. By implementing waste heat recovery techniques and exploring alternative options, future energy hubs can strengthen their business models and play a crucial role in Europe's green transition and clean fuel production. • Pinch analysis is combined with a multi-carrier energy system model. • Excess heat utilization value from Power-to-X production in energy hubs is assessed. • Effective use of excess heat significantly reduces waste heat and gas consumption. • Connection of large-scale electrolysis to district heating provides additional value. [ABSTRACT FROM AUTHOR]

Cement production is responsible for about eight percent of global CO2 emissions. A potential use for CO2 is the production of synthetic fuels through power-to-X (PtX) processes. For this purpose, a potential analysis is performed in which the possibilities for CO2 avoidance and CO2 capture and utilization (CCU) in the cement manufacturing process are evaluated. Based on the potential analysis, three scenarios for the development of the German cement industry until 2050 are developed and displayed in geo-referenced form, yielding potential locations for PtX plants. Results show that it is unlikely that cement can be fully replaced by alternative construction methods or new types of binders from today’s perspective. Measures to reduce CO2 emissions in cement production are limited, especially due to the restricted possibilities to replace limestone as feedstock. In an intermediate scenario, CO2 emissions in cement production decrease by 35% until 2050 compared to the average value from the 2014–2018 reference period. For CCU to be introduced at cement plants, the additional costs must be compensated, either through revenues from CO2 certificates or economic and regulatory incentives.