Chemical Energy Carriers Research Articles

Low carbon collaborative planning of integrated hydrogen-ammonia system and power distribution network

The conversion of renewable energy into chemical energy carriers, such as ammonia, enhances the accommodation of renewable energy for power distribution networks (PDN) and supports the decarbonization for ammonia production systems (APS). This paper addresses the integration of PDN with APS through a collaborative planning considering a carbon emission flow (CEF) model. A collaborative planning model with carbon emissions constraints is designed, and a sensitivity analysis is performed to evaluate the impact of varying renewable energy costs on the system. To further reduce carbon emissions from green ammonia production and stabilize renewable energy volatility, a nodal CEF model that incorporates energy storage systems (ESS), wind turbines (WT), and photovoltaics (PV) is proposed. The economic feasibility of the proposed model is verified via comprehensive experiments. Numerical results show that collaborative scheduling reduces both costs and carbon emissions in PDN and APS. Implementing a carbon tax encourages the transition from grey to blue ammonia production, while a decrease in renewable energy costs further promotes the shift from blue to green ammonia. Besides this, the analysis indicates that integrating long-term operation of WT and PV, together with low-cost renewable electricity and ESS, boosts the economic efficiency of the green ammonia production system.

Hydrogen and Hydrocarbon Fuels from Abundant Resources and Solar Energy: Current Activities and Perspectives in DLR’s Institute of Future Fuels

Abstract Chemical energy carriers, centralized around Hydrogen products, will play an essential role in the energy system of the future. The advantages of comparable power density and reliability to fossil fuels, as well as their versatile applications, make them an important component of the energy transition. DLR is conducting research on technologies that ensure the efficient production of chemical energy carriers. De-carbonizing the energy system and of industry needs not only electricity from carbon-neutral sources but also green fuels. DLR’s Institute of Future Fuels steps in at that point by developing and investigating production methods for hydrogen and synthetic hydrocarbon fuels. Those are mostly based on the utilisation of concentrated sunlight but in additionally also on other renewable resources. The development goes all along the way of identifying and qualifying suitable functional materials, over integrating them in specific components allowing to introduce renewable energy into the process, towards the demonstration of a representative overall process along the chain from raw materials to the targeted fuel. Hydrogen plays a key role in this context, either as the fuels itself or as a core building block of synthetic hydrocarbon fuels and chemicals. The institute has a specific focus on thermochemical processes, in particular for water and CO2 splitting, but also on air separation, thermochemical heat storage and upgrading of biomass and other hydrocarbons.

Giant nanomechanical energy storage capacity in twisted single-walled carbon nanotube ropes

A sustainable society requires high-energy storage devices characterized by lightness, compactness, a long life and superior safety, surpassing current battery and supercapacitor technologies. Single-walled carbon nanotubes (SWCNTs), which typically exhibit great toughness, have emerged as promising candidates for innovative energy storage solutions. Here we produced SWCNT ropes wrapped in thermoplastic polyurethane elastomers, and demonstrated experimentally that a twisted rope composed of these SWCNTs possesses the remarkable ability to reversibly store nanomechanical energy. Notably, the gravimetric energy density of these twisted ropes reaches up to 2.1 MJ kg−1, exceeding the energy storage capacity of mechanical steel springs by over four orders of magnitude and surpassing advanced lithium-ion batteries by a factor of three. In contrast to chemical and electrochemical energy carriers, the nanomechanical energy stored in a twisted SWCNT rope is safe even in hostile environments. This energy does not deplete over time and is accessible at temperatures ranging from −60 to +100 °C.

Process Engineering Analysis of Transport Options for Green Hydrogen and Green Hydrogen Derivatives

The transition of the German economy and energy system toward CO2 neutrality requires large quantities of climate‐friendly chemical energy carriers, such as green hydrogen, to be imported. The decision on the most favorable import routes must consider its energy efficiency To respect the remaining CO2 budget to achieve the 1.5° climate target, the implementation time and therefore additional evaluation criteria must be taken into account. In this article, as a first step, the energy utilization rate () for different hydrogen import options is evaluated. Starting off from hydrogen at 25 °C and 25 bar produced in the exporting country, liquid hydrogen, ammonia, liquid methane (Green LNG), methanol, and liquid organic hydrogen carrier are considered as chemical energy carries. Liquid hydrogen is in future the most efficient import option ( = 7%) when gaseous hydrogen is supplied in the importing country. When direct utilization of the H2 derivatives is considered, the ammonia import route has the highest energy utilization rate with 77%. If point sources for CO2 are considered, direct utilization of methanol ( = 83%) and Green LNG ( = 76%) are energetically favorable import options. Additional significant criteria for a technological assessment are maturity of technologies, available capacities, infrastructures, and production processes.

Direct recovery of electro-synthesized ammonia from low-concentration nitric oxide using pulse electrodeposited Cu/C catalyst in a catholyte-free system

Electrochemical production of ammonia (NH3) from nitric oxide (NO) offers a sustainable and environmentally friendly way to convert a nitrogenous pollutant into a valuable chemical feedstock and energy carrier. However, practical challenges in the electrochemical NO-to-NH3 conversion stem from mass transport limitations due to low NO concentrations in real-world streams and the need for post-purification of synthesized NH3. In this study, by synergistically developing an electrocatalyst (pulse-electrodeposited copper) and implementing a catholyte-free cell configuration with advantages of (i) facile NO transport, (ii) inhibited side reaction, and (iii) direct NH3 recovery in an external acid, we showcase an NH3 Faradaic efficiency of 85.6 % and a production rate of 53.4 μmol cm−2h−1 starting from 500 ppm NO. Crucially, the electro-synthesized NH3 was directly recovered as a high-purity aqueous ammonium sulfate solution comparable to industrial-grade quality. This approach opens the door to transforming waste into resources in a more energy-efficient and straightforward manner.

Strategies to achieve effective nitrogen activation

AbstractAmmonia serves as a crucial chemical raw material and hydrogen energy carrier. Aqueous electrocatalytic nitrogen reduction reaction (NRR), powered by renewable energy, has attracted tremendous interest during the past few years. Although some achievements have been revealed in aqueous NRR, significant challenges have also been identified. The activity and selectivity are fundamentally limited by nitrogen activation and competitive hydrogen evolution. This review focuses on the hurdles of nitrogen activation and delves into complementary strategies, including materials design and system optimization (reactor, electrolyte, and mediator). Then, it introduces advanced interdisciplinary technologies that have recently emerged for nitrogen activation using high‐energy physics such as plasma and triboelectrification. With a better understanding of the corresponding reaction mechanisms in the coming years, these technologies have the potential to be extended in further applications. This review provides further insight into the reaction mechanisms of selectivity and stability of different reaction systems. We then recommend a rigorous and detailed protocol for investigating NRR performance and also highlight several potential research directions in this exciting field, coupling with advanced interdisciplinary applications, in situ/operando characterizations, and theoretical calculations.

Electrical-energy storage into chemical-energy carriers by combining or integrating electrochemistry and biology

Our societies must reconsider current industrial practices and find carbon-neutral alternatives to avoid the detrimental environmental effects that come with the release of greenhouse gases from fossil-energy carriers.

Противодействие живых систем развитию возрастной катаракты. Физико-химическое объяснение

Simultaneous processes occur in living systems that lead to both an increase in entropy (chaos) and its decrease. A decrease in entropy is possible only in open systems, associated with a contin-uous flow of energy-intensive compounds into them, such as glucose, the oxidation of which is energetically associated with the synthesis of ATP, the universal carrier of chemical energy to en-sure functioning of living systems. When energy-intensive compounds are oxidized, entropy in-creases, and when ATP is synthesized, it decreases. In living systems, not only reactions associated with the synthesis of ATP and their functioning occur, but also aging does, namely, the oxidation of hydrophobic formations in cells, in particular, the membrane matrix, following the type of chain reactions with degenerate branching. The development of such chain reactions of oxidation in cells can be prevented by the penetration into them of various antioxidants, for example, resvera-trol, which is contained in grapes and other plants, and quenchers of molecular oxygen in the sin-glet state, for example, iodides, as well as by creating cyclic processes involving desaturases that prevent an increase in viscosity in the matrix of membranes up to certain limiting values, after which cell death becomes inevitable. In this regard, the processes leading to cataracts (clouding of the eye lenses) are indicative. In the absence of desaturases in the lens fibers of rats, exposure to UV light leads to cataracts in 2–4 months, while the presence of desaturases in human eye lens fi-bers makes it possible to avoid the occurrence of cataracts for many decades. The reaction of con-version of lipids with saturated fatty acids into unsaturated ones, catalyzed by desaturases, leads to counteracting the aging of the membrane matrix. The vital feature of this reaction is that it oc-curs only when the membrane matrix is cured. This reaction first leads to liquefaction of the ma-trix up to a certain state, after which it stops. The reasons leading either to revival of desaturase or to decrease in its activity are discussed in this article.

Accelerated design of Power-to-X process chains for transient operation using Recurrent Neural Networks

Climate change requires a reorientation towards renewable energy generation and storage technologies, especially from solar and wind-based sources. Power-to-X technologies offer a promising way to convert renewable energy into chemical energy carriers based on green hydrogen. A major obstacle to the implementation of such systems is the need to operate the plants dynamically to account for fluctuations. The conventional design of these process chains is usually done through complex dynamic flowsheet simulations, which require specialized engineers and are therefore time-consuming and costly.This study presents an innovative approach to build surrogate models of process chains by using Recurrent Neural Networks and in detail Long Short-Term Memory. To establish a basis for the training data of these models, process simulations were performed with respect to critical parameters for plant dynamics and capacity adjustment. The developed models can represent the dynamics of the process and allow the estimation of annual production volumes for different geographical locations, based on local wind speeds. In addition, plant-specific variables, such as the number of cells in hydrogen-producing electrolysis, can be modified and optimized. These models open the possibility of making informed decisions at an early project stage and reduce the risk of implementing dynamic Power-to-X plants.

Improvement of Current Efficiency of PEM Electrolyzer for Organic Chemical Hydride Energy Carrier Production with Water Electrolysis by Humidified Air Supply to Anode

Introduciton To improve hydrogen energy carrier synthesis, we have studied toluene electrohydrogenation and water decomposition using proton exchange membrane (PEM) electrolysis. The cathode reaction is electrohydrogenation of toluene to synthesis methylcyclohexane instead of hydrogen evolution reaction of water electrolysis. Only side reaction of the cathode is hydrogen evolution reaction, which was affected by electroosmotic water from the anode to cathode. Sulfuric acid solution feeds as anolyte that is not only reactant reduces water transportation and increases current efficiency [1, 2]. As practical system, water transportation from anode to cathode should be suppressed without sulfuric acid utilizationIn this study, to improve current efficiency by water management, we have investigated humidified air feed to reduce water transfer to cathode compare with liquid water feed. Experimental A single cell electrolyzer made of titanium with 16 cm2 of projected electrode area was used. Figure 1 shows the schematic drawing of toluene direct hydrogenation electrolyzers with humidified air feed. Membrane-electrodes assembly was consisted of Nafion® 117 (DuPont), 0.6 mg cm-2 of PtRu/C (TEC61E54, TKK, I/C = 0.8) cathode catalyst layer and 2.0 mg cm-2 of IrOx (TEC77100, TKK, I/IrOx = 0.28). Cathode backing was a carbon paper (10BC, SGL) of 0.02 mg cm-2 of Pt loading, which works flow filed of toluene-methylcyclohexane, too. Anode baking as a Pt plated sintered Ti web (Bekaert), and anode flow filed was serpentine type. 10 mL min-1 of toluene or 10% toluene – methylcyclohexane was fed to cathode. 5.0 L min-1 (313 mL min-1 cm-2) of fully humidified air or liquid water was fed to cathode. Operation temperature was 80oC. Internal resistance was determined by high frequency intercept of real axis of the electrochemical impedance spectroscopy in the current density region between 0.1 to 0.6 A cm-2. The water transportation through the membrane was determined by separated water in outlet liquid from cathode during constant current electrolysis, and the Faraday efficiency was determined by generated gas volume from the cathode, simultaneously. Results and discussion Figure 2 shows the cell voltage and current efficiency as a function of the current density for 10% toluene-methylcyclohexane or 100% toluene to cathode and 5.0 L min-1 of fully humidified air or liquid water to anode feed. Cell voltages were almost same for all experiments in less than 0.3 Acm-2 of current density region, while cell voltages of humidified air feed were higher than that of liquid water feed in higher current density region. Here, internal resistance of humidified air and liquid water feed were 0.29 and 0.21 Ω cm2. Therefore, membrane condition of the humidified air feed was drier than that of the liquid water feed. Water transportation through the membrane around 0.2 mg min-1 cm-2, which was less than 1/10 of the liquid water or 1 M H2SO4 feed electrolysis. The current efficiency for 100% toluene feed was more than 95% at 1 A cm-2, and slightly decreased with current density. In this case, the current efficiency of the liquid water feed was a little higher than that of the humidified air feed. The current efficiency of the humidified air feed was more than 95% up to 0.5 Acm-2, while the current efficiency of the liquid water feed decreased 95% around 0.2 Acm-2. In addition, the current efficiency of 10% toluene-methylcyclohexane significantly decrease with current density.The current efficiency would be affected by the cathode potential and toluene transportation in the catalyst layer. For the 100% toluene feed, toluene transportation would less affect and cathode potential would much affect to the current efficiency. Larger internal resistance of the humidified air feed would correspond to dry condition of cathode ionomer, and it would decrease the cathode potential. Therefore, the current efficiency of humidified air was slightly lower than liquid water feed. On the other hand, the current efficiency of 10% toluene feed would be controlled by toluene transportation in the cathode catalyst layer and is significantly affected by the water transportation through the membrane. Therefore, the current efficiency of the humidified air feed significantly higher than that of the liquid water feed. Acknowledgement This study was based on results obtained from the Development of Fundamental Technology for Advancement of Water Electrolysis Hydrogen Production in Advancement of Hydrogen Technologies and Utilization Project (P14021) commissioned by the New Energy and Industrial Technology Development Organization (NEDO). References Nagasawa, K. Tanimoto, J. Koike, K. Ikegami, S. Mitsushima, J Power Sources, 439, 227070 (2019).Oi, K. Nagasawa, T. Takamura, Y. Misu, K. Matsuoka, S. Mitsushima, ECS Meeting s, MA2021-02, 1737 (2021). Figure 1

Research on design and multi-frequency scheduling optimization method for flexible green ammonia system

As an important chemical product and energy carrier, green ammonia is a way to consume large quantities of green hydrogen produced from renewable electricity. For the optimization of the green ammonia production systems, a primary problem is to solve the electricity-hydrogen-ammonia matching problem under multi-frequency and multi-amplitude load fluctuations. In this work, a method for capacity designing and scheduling optimization of a hybrid multi-frequency flexible green ammonia system is constructed. The method can be applied to design the whole green ammonia system in grid-connected and isolated scenarios. The established model can accurately describe the electricity-hydrogen-ammonia matching characteristics of each module. Furthermore, many important practical engineering constraints are taken into account, such as the operating time of the chemical device, and the flexibility of the ammonia device. This work verifies the effectiveness of the proposed method based on a real case, and the impact of load range, adjustment speed, and adjustment frequency of the ammonia synthesis process on the product cost and module capacity.

Metabolic heat production impacts industrial upscaling of ex situ biomethanation trickle-bed reactors

Conversion of electrical energy and CO2 to a chemical energy carrier in the form of biomethane, can be carried out through the process chain of biomethanation. Although this process provides a promising source of fossil-free natural gas, limited experience with upscaling still hampers its industrial maturation. Through methanation of raw biogas in a 225 L pilot-scale trickle-bed reactor by use of electrolysis-derived H2, this work uniquely elucidates how metabolic heat from the exothermic biomethanation process present both a challenge and opportunity for upscaling the biomethanation technology. For the first time, a trickle-bed reactor subject to periodic trickling is characterised based on axial temperature profiles as a result of exothermic heat release, in up-flow and down-flow gas configurations. At maximum, reactor core temperatures in the upper thermophilic range (78 and 83 °C) were recorded in certain axial locations, respectively, for substrate gas flow rates of 3.0 and 7.5 NLCO2/Lreactor/d. During a long-term continuous period at 3.0 NLCO2/Lreactor/d, biomethane production with a CH4 content of ≥95 vol% was measured, in both the reactor’s up-flow and down-flow gas configurations. The alternating flow directions and periodic trickling affected both hydrodynamic factors and thermal stability, showing the importance of preheating and humidifying gaseous feed streams and the implementation of a metabolic heat management strategy, by way of cooling, to provide thermal and reaction stability for future upscaling of trickle-bed biomethanation reactors for biological power-to-gas.

Numerical investigation on the effect of hydrogen share in NH3/H2 blends in a turbulent lean-premixed swirl burner

Climate change and the energy crisis urge the transition from fossil to renewable fuels. Ammonia and hydrogen are the most versatile carbon-free chemical energy carriers. Hydrogen-diluted ammonia combustion can drastically lower the emission of nitrogen oxides. The present paper focuses on the numerical analysis of ammonia/hydrogen combustion in a lean-premixed swirl burner, highlighting the effect of hydrogen share and equivalence ratio. The hydrogen share notably influences the axial position of the heat release maximum due to the higher reactivity, while it marginally influences the global velocity field. Unburned ammonia was observed at lean condition and low hydrogen concentration. At ultra-lean conditions, nitrogen oxide emission increases with hydrogen content, while a maximum can be reached by increasing the equivalence ratio. The values are compared to experimental data from the literature. Dinitrogen oxide emission decreases with both hydrogen concentration and equivalence ratio. Non-reacting flow field was validated by Particle Image Velocimetry measurements.

Industrial hydrogen hub planning and operation with multi-scale optimisation

Hydrogen is a chemical product and energy carrier that, if used in the right way, could help decarbonise many sectors such as transportation, electricity production, the steel industry or petroleum refining. However, hydrogen’s versatility, which a strength in terms of energy transition, makes its deployment more complex to plan. This study provides a methodology aiming to understand the evolution of a local energy system including different coupled energy vectors: natural gas, biomethane, hydrogen and electricity. A bottom-up multi-vector linear optimisation provides some elements regarding the planning and hourly operation of hydrogen production and storage infrastructures. The methodology consists in three steps. First, hydrogen demand and the technical context is modelled by defining different evolution scenarios. Then, a first optimisation at the country scale is conducted in order to define the boundary conditions for the third step, where the local hydrogen ecosystem evolution is optimised. This methodology was used to study the evolution of the industrial harbour of Fos-sur-mer in south of France. The results show that electrolysis is expected to grow, replacing existing technologies such as conventional steam methane reforming (SMR). However, depending on the context, keeping the SMR as peak production capacities can bring more flexibility into the local system and thus; improve the competitiveness of hydrogen. For the studied industrial cluster in south of France, we found an average levelised cost of hydrogen of 2.9 €/kgH2 in a reference scenario. This value can decrease to 2.5 €/kgH2 in the most flexible case with large underground storage and go up to 4 €/kgH2 in the case where SMR are banned from 2030. If space is available on a local level, then the development of dedicated renewables together with electrolysis seems to be the optimal trajectory.

Surface Conversion of ZnO Tetrapods Produces Pinhole-Free ZIF-8 Layers for Selective and Sensitive H2 Sensing Even in Pure Methane.

As the necessary transition to a supply of renewable energy moves forward rapidly, hydrogen (H2) becomes increasingly important as a green chemical energy carrier. The manifold applications associated with the use of hydrogen in the energy sector require sensor materials that can efficiently detect H2 in small quantities and in gas mixtures. As a possible candidate, we here present a metal-organic framework (MOF, namely ZIF-8) functionalized metal-oxide gas sensor (MOS, namely ZnO). The gas sensor is based on single-crystalline tetrapodal ZnO (t-ZnO) microparticles, which are coated with a thin layer of ZIF-8 ([Zn(C4H5N2)2]) by a ZnO conversion reaction to obtain t-ZnO@ZIF-8 (core@shell) composites. The vapor-phase synthesis enables ZIF-8 thickness control as shown by powder X-ray diffraction, thermogravimetric analysis, and N2 sorption measurements. Gas-sensing measurements of a single microrod of t-ZnO@ZIF-8 composite demonstrate the synergistic benefits of both MOS sensors and MOFs, resulting in an outstanding high selectivity, sensitivity (S ≅ 546), and response times (1-2 s) to 100 ppm H2 in the air at a low operation temperature of 100 °C. Under these conditions, no response to acetone, n-butanol, methane, ethanol, ammonia, 2-propanol, and carbon dioxide was observed. Thereby, the sensor is able to reliably detect H2 in mixtures with air and even methane, with the latter being highly important for determining the H2 dilution level in natural gas pipelines, which is of great importance to the energy sector.

Scheduling power-to-ammonia plants considering uncertainty and periodicity of electricity prices

Developing affordable and scalable energy storage solutions are essential to decarbonizing power systems. The conversion of renewable electricity into chemical energy carriers such as ammonia has attracted extensive attention from academia and industry. Many Power-to-Ammonia (PtA) plants have been conceptualized and developed worldwide in recent years. The PtA plant is an integration of multiple electrochemical processes, each with a distinct set of operational constraints and cost structure. One of the problems in the operation of PtA plants is the optimal scheduling of the hydrogen buffer in PtA plants considering the operational characteristics of electrochemical processes and the volatility and uncertainty of electricity prices. In this paper, a two-stage Markov-Decision-Process (MDP) approach is proposed. The computational challenges brought by the infinite optimization horizon and non-concavity of cost functions are resolved. The first stage solution is based on the periodic MDP approach, which captures the periodic structure of electricity prices. The second stage solution gives optimal real-time decisions based on a rolling-horizon MDP approach. Numerical results show that the accurate representations of the cost functions and the optimization horizon using the proposed method are necessary, while the linearization of cost functions and the truncation of the optimization horizon lead to notable deviations from the optimality.

The Carbon Footprint of Hydrogen Produced with State-of-the-Art Photovoltaic Electricity Using Life-Cycle Assessment Methodology

The production of hydrogen as both chemical feed and energy carrier using low-carbon technologies is one of the solutions to reach net-zero emissions. This paper, firstly, reviews the publications on the life-cycle assessment of photovoltaic (PV)-based hydrogen production focused on the carbon footprint. Secondly, it updates the global warming potential (GWP) values of this H2 production process considering the state-of-the-art PV panels for installation in Italy. In the literature, H2 produced in Europe and the rest of the world results in a mean GWP equal to 4.83 and 3.82 kg CO2 eq./kg H2, respectively, in which PV systems contribute the highest share. The average efficiency of PV panels assumed in the literature is lower than the current PV modules. Updating the supply chain, efficiency, and manufacturing energy and material flows of PV modules can decrease the GWP value of the H2 produced by nearly 60% (1.75 kg CO2 eq./kg H2, with use of alkaline electrolyzer) in the Italian context, which can be further reduced with advancements in PV panels or electrolysis efficiency. The study proves that advancement in the PV industry and additional savings in the electrolyzer’s electrical demand can further decrease the carbon footprint of PV-based H2.

Techno-economic analysis to identify the optimal conditions for green hydrogen production

The intermittency of renewable energy sources necessitates energy storage to meet the full demand and balancing requirements of the grid. Green hydrogen (H2) is a chemical energy carrier that can be used in a flexible manner and store large amounts of energy for long periods of time. This techno-economic analysis investigates H2 production from wind using commercially available desalination and electrolysis units. Proton exchange membrane and alkaline electrolyser units are utilised and compared. The intermittency of wind is examined, with comparison against grid-bought electricity. A model is developed to determine the selling price required to ensure profitability over a 10-year period. Firstly, where H2 is produced using energy from the grid, with electricity purchased when below a specified price point or between specified hours. In the second scenario a wind turbine is owned by the user and the electricity price is not considered, while the turbine capital expenditure is. The price of H2 production from wind is found to be comparable with natural gas derived H2 at a larger scale, with a minimum selling price calculated to be 4.85 £/kg at a setpoint of 500 kg of H2/hr. At a setpoint of 50 kg of H2/hr, this is significantly higher at 12.10 £/kg. In both cases, the alkaline electrolyser produced cheaper H2. This study demonstrates an economy of scale with H2 prices decreasing with increased scale. H2 prices are also closely linked to the capital expenditure, with the equipment size, space and safety identified as limiting factors.

Catalytic CH4 pyrolysis promoted by the interface of a molten metal–salt hybrid system

Hydrogen is an important chemical feedstock and energy carrier. A promising idea for a bridging technology for net-zero carbon emission is the catalytic pyrolysis of natural gas into hydrogen and solid carbon. However, the activation of methane and recovery of the produced carbon with high purity are the main hurdles for process commercialization. In the present study, molten metal–salt layered reaction beds for methane pyrolysis were investigated to determine the effect of the interface and the optimal ratio of metal and salt. These layered catalyst beds had several advantages over pure molten metal or molten salt catalyst beds. First, the length of the molten metal layer could be minimized to a level where the methane bubbles only touch the metal–salt interface, enhancing the economic feasibility of the process. Second, the metal–salt interface could delay bubble rising in proportion to the interfacial tension. Third, the molten salt layer could wash out the residual metal traces from the produced carbon, improving the carbon purity. This study would provide hints for building economically viable catalytic pyrolysis of methane based on molten metal-salt layered reaction bed.

Numerical Modeling and Simulation of the Solid Oxide Cell Stacks and Metal Interconnect Oxidation with OpenFOAM

Solid oxide cells are capable of efficiently converting various chemical energy carriers to electricity and vice versa. The urgent challenge nowadays is the faster degradation rate compared with other fuel cell/electrolyzer technologies. To understand the degradation mechanisms, simulation of a solid oxide cell is helpful. Since most previous research developed models using commercial software, such as COMSOL and ANSYS Fluent, a gap for knowledge transfer is being gradually formed between academia and industry due to licensing issues. This paper introduces a multiphysics model, developed by a computational code, openFuelCell2. The code is implemented with an open-source library, OpenFOAM. It accounts for momentum transfer, mass transfer, electrochemical reactions and metal interconnect oxidation. The model can precisely predict I–V curves under different temperatures, fuel humidity and operation modes. Comparison between OpenFOAM and COMSOL simulations shows good agreement. The metal interconnect oxidation is modeled, which can predict the thickness of the oxide scale under different protective coatings. Simulations are conducted by assuming an ultra-thin film resistance on the rib surface. It is revealed that coatings fabricated by atmospheric plasma spraying can efficiently prevent metal interconnect oxidation, with a contribution of only 0.53 % to the total degradation rate.