Steam Methane Reforming Research Articles

Techno-economic Analysis and Optimization of Intensified, Large-Scale Hydrogen Production with Membrane Reactors.

Steam methane reforming (SMR) currently supplies 76% of the world's hydrogen (H2) demand, totaling ∼70 million tonnes per year. Developments in H2 production technologies are required to meet the rising demand for cleaner, less costly H2. Therefore, palladium membrane reactors (Pd-MR) have received significant attention for their ability to increase the efficiency of traditional SMR. This study performs novel economic analyses and constrained, nonlinear optimizations on an intensified SMR process with a Pd-MR. The optimization extends beyond the membrane's operation to present process set points for both the conventional and intensified H2 processes. Despite increased compressor and membrane capital costs along with electric utility costs, the SMR-MR design offers reductions in the natural gas usage and annual costs. Economic comparisons between each plant show Pd membrane costs greater than $25 000/m2 are required to break even with the conventional design for membrane lifetimes of 1-3 years. Based on the optimized SMR-MR process, this study concludes with sensitivity analyses on the design, operational, and cost parameters for the intensified SMR-MR process. Overall, with further developments of Pd membranes for increased stability and lifetime, the proposed SMR-MR design is thus profitable and suitable for intensification of H2 production.

Steam reforming of methane over nickel-aluminum spinel-derived catalyst

Despite steam reforming of methane (SRM) has been the dominant way to produce hydrogen in industrial owing to its large hydrogen production capacity, easy accessibility of feedstocks and relative low cost, the development of high-efficient catalysts is still of great significance. In this work, we report the synthesis, characterizations and evaluation of Nickel-aluminum spinel (NiAl2O4) catalyst in SRM reaction. Compared with Ni/γ-Al2O3 catalyst prepared by impregnation, NiAl2O4 presents higher methane conversion. Virous of characterizations exhibit NiAl2O4 possesses higher distribution of Ni and smaller Ni nanoparticle size, which is one of advantages for its high activity. Another vital reason is the generation of oxygen vacancies in spinel during the reduction, which is beneficial for the activation of water. Moreover, NiAl2O4 catalyst shows extremely stability without obvious deactivation in 160 h. This study illustrates that the construction of catalyst with high activity and stability via NiAl2O4 spinel and reals its high activity origination.

Environmental performance of nonthermal plasma dry and conventional steam reforming of methane for hydrogen production: Application of life cycle assessment methodology

The environmental performance of nonthermal plasma assisted dry reforming of methane (NTP-DRM) for hydrogen production from methane rich natural gas is investigated and compared with the current state of the art steam reforming technology through a cradle-to-gate life cycle assessment (LCA). The NTP-DRM technologies studied in this analysis include dielectric barrier, microwave, and pulsed plasma discharges. Due to the level of technology the study is considered as the prospective LCA of selected types of NTP-DRMs for hydrogen production. Of these, the NTP-DRM using microwave and pulsed plasma presented better environmental performance. The impact categories include midpoints levels applying TRACI 2.1 and AWARE for the water scarcity, using ecoinvent 3.8 and US NETL databases. The scenario analysis regarding carbon dioxide, electricity, and natural gas sources, revealed the highly dependency of NTP-DRMs technologies environmental performance to the energy efficiency of the processes. In terms of steam reforming of methane (SRM) despite the main contribution of steam use in the technology environmental performance, the uncertainty analysis showed higher sensitivity to natural gas input. Investigation showed that using renewable energy sources can have significant improvement regarding NTP-DRMs environmental performance and specifically global warming potential. Accordingly, at their current reactant conversion and product selectivity reaching the energy use of eV per molecule of reactant equal or less than 2, can be a proper target for the studied best case NTP-DRM to make their environmental behavior competitive with the state-of-the-art SRM technologies.

Conceptual process design and technoeconomic analysis of an e-ammonia plant: Green H2 and cryogenic air separation coupled with Haber-Bosch process

Manufacturing low-carbon ammonia (NH3) is paramount for the green transition of the chemical industry and society at large. The conventional Haber-Bosch (HB) process based on steam methane reforming (SMR) entails whopping CO2 emissions (i.e., 400 Mt y−1), therefore we propose a sustainable plant design comprising water electrolysis and cryogenic distillation for H2 and N2 production, respectively. This electrified configuration powered by wind energy affords 80% lower carbon emissions than the conventional SMR-based process. However, the electrolyser unit can represent between 36 and 61% of the total capital cost, depending on its energy efficiency, and its high energy demand drives the electricity cost which accounts for more than 68% of the plant operational costs. Thus, even with anticipated improvements in efficiency of the electrolyser unit, the Levelized Cost of Production (LCOP) of e-NH3 in a 2050 scenario is 65% higher than the current benchmark; nonetheless, the two processes could be equally viable with a 135.8 $ tCO2−1 carbon penalty on the average conventional process. Notably, the cost of electricity is the most prominent cost driver in the e-process, which could be more economically viable than the fossil counterpart with electricity prices below 12.5 $ MWh−1. These findings provide evidence that the proposed e-process can replace the commercial benchmark in small-scale, standalone applications.

Performance of SOFCs using model waste gases: A case study

Municipal solid waste landfills and steelmaking industry produce large amounts of high-calorific waste gases which can be utilized for energy generation. The possibility of SOFC operation using model landfill and coke-oven gases without external steam reforming of methane was experimentally demonstrated employing a SOFC short-stack comprising two electrolyte-supported membrane-electrode assemblies of planar geometry. The current-voltage dependencies, polarization resistances and composition of the effluent fuel oxidation products were tested as function of time during approximately 600 h. In all cases, complete conversion of methane occurs at the anodes even under open-circuit conditions. The maximum power density of 183 mW/cm2 was achieved for the humidified landfill gas at 850 °C and current density of 320 mA/cm2; the fuel utilization was 67% at current density of 222 mA/cm2. Neither microstructural changes nor carbon deposition were revealed by microscopic analyses after the SOFC tests. However, thermodynamic estimations showed that local anode coking may occur in a narrow zone near the fuel inlet where the fuel utilization only starts. This process correlating with local cooling detected in the vicinity of fuel inlet, may be responsible for degradation in the SOFC performance observed in the waste gas utilization regime.

Recent Advances in Bimetallic Catalysts for Methane Steam Reforming in Hydrogen Production: Current Trends, Challenges, and Future Prospects.

As energy demand continues to rise and the global population steadily grows, there is a growing interest in exploring alternative, clean, and renewable energy sources. The search for alternatives, such as green hydrogen, as both a fuel and an industrial feedstock, is intensifying. Methane steam reforming (MSR) has long been considered a primary method for hydrogen production, despite its numerous advantages, the activity and stability of the conventional Ni catalysts are major concerns due to carbon formation and metal sintering at high temperatures, posing significant drawbacks to the process. In recent years, significant attention has been given to bimetallic catalysts as a potential solution to overcome the challenges associated with methane steam reforming. Thus, this review focuses on the recent advancements in bimetallic catalysts for hydrogen production through methane steam reforming. The review explores various aspects including reactor type, catalyst selection, and the impact of different operating parameters such as reaction temperature, pressure, feed composition, reactor configuration, and feed and sweep gas flow rates. The analysis and discussion revolve around key performance indicators such as methane conversion, hydrogen recovery, and hydrogen yield.

How sustainable and profitable are large-scale hydrogen production plants from CH4 and H2S?

The large-scale production of hydrogen through mature technologies such as steam methane reforming (SMR) has set a benchmark for emerging hydrogen production processes to gauge their economic viability for the hydrogen economy. In this work, we use detailed process modeling to perform a techno-economic and environmental assessments on the potential of alternative emerging hydrogen production processes based on H2S utilization including H2S-methane reforming (H2SMR), and H2S pyrolysis (H2SPyrol) compared to steam methane reforming (SMR), SMR with CO2 capture, storage, and utilization (CCUS), and CH4 pyrolysis (CH4Pyrol). Technically, the energy intensity of these processes in terms of electrical and thermal energy consumption was ranked as CH4Pyrol < SMR < SMR + CCUS < H2SMR < H2SPyrol. However, lower CH4 feedstock and absence of direct CO2 emissions were seen for H2SMR for the same target hydrogen production. Economically, both H2S-based hydrogen production technologies were competitive with levelized cost of hydrogen (LCOH) of $-1.000 and $3.537 per kg for H2SMR and H2SPyrol, respectively, compared to LCOH of $2.400, $2.410, and $1.930 per kg for SMR, SMR + CCUS, and CH4Pyrol, respectively, with consideration for by-product sales, and sensitivity analysis to their market prices and effect of carbon taxes. Environmentally, H2SMR and H2SPyrol revealed their lower contribution to global warming, with the absence of direct CO2 emissions, qualifying as low carbon hydrogen production processes. Although direct CO2 emissions are missing from CH4Pyrol, its qualification as low carbon hydrogen producer hinges on the level of decarbonization for the electricity grid. Conversely, the water footprint of H2S-based hydrogen production process remains to be the largest due to the indirect consumption of cooling water required for product recovery, although not necessarily impacting water stress, due to the lower quality of water required for cooling. In summary, transitioning from SMR wo/w CCUS to H2SMR or CH4Pyrol seems to be potentially attractive for competing with current processes for H2 production within the existing policies for decarbonization.

Prospects for hydrogen fuel cell vehicles to decarbonize road transport

This paper explores the role of hydrogen fuel cell vehicles (HFCVs) in helping to meet global climate goals of limiting long-term greenhouse gas (GHG) emissions to 1.5 °C. Employing the GREET Model and data from the International Energy Agency (IEA), the study comprehensively compares the full fuel-cycle emission profiles of HFCVs and battery electric vehicles (BEVs). The paper conducts an in-depth examination of the interplay between the carbon intensity of the electric grid and the resulting GHG emissions within the context of refueling HFCV vehicles via electrolyzers, and the analysis draws a comparison to BEVs charged using the same electric grid. The study finds that while emissions for BEVs increase, emissions for HFCVs are significantly larger when HFCVs are refueled from retail outlets producing hydrogen via electrolysis from grid electricity—a finding that was not previously reached in the current literature. The research underscores that countries operating electric grids characterized by high GHG emissions or lacking robust pathways to emission reduction would face suboptimal outcomes by adopting HFCVs powered by hydrogen sourced from distributed grid electricity generation. The gCO2e/mi for BEVs and HFCVs are also calculated when the electricity is produced from renewable energy resources. When electricity is derived from renewable energy sources, it becomes evident that the gCO2e/mi for both HFCVs and BEVs converge towards ‘zero’. The emission metric of gCO2e/mile for a HFCV refueled with the hydrogen produced from natural gas via steam methane reforming (SMR) without carbon capture utilization and storage (CCUS), stands at 105 gCO2e/mile, whereas in the absence of CCUS, it escalates notably to 247 gCO2e/mile, an approximate 150% increase in stark contrast to CCUS inclusion. This quantitative portrayal serves to underscore the substantial potential for curtailing carbon footprints achievable through the integration of CCUS, thereby amplifying its significance within the realm of hydrogen-based transportation and the broader purview of climate change mitigation endeavors. In order to provide a comprehensive perspective, the study delves into the examination of hydrogen production pathways and associated costs for the years 2021, 2030, and 2050. The forecasted supply costs are elucidated, particularly in relation to the potential hydrogen supply originating from variable renewable energy (solar PV and wind) sources and from CCUS-equipped hydrogen production facilities (considering the project pipeline of projects upto 2030). These factors are of substantial importance in shaping the hydrogen supply landscape and subsequently influencing the adoption of HFCVs in the market. The study also examines the cost implications of hydrogen delivery for varying transportation distances (for 2030), acknowledging their important role in the broader context. The challenges posed by the integration of variable renewable energy sources are also addressed, along with the imperative for effective energy storage solutions. This discourse unfolds within the overarching framework of the energy transition, prominently characterized by the ascendancy of solar PV and wind energy. The intricate interplay of these aspects assumes a critical role in shaping the trajectory of future hydrogen supply dynamics over the medium and long term.

Transport of Steam-Gas Mixture in Hydrodynamic Devices: A Numerical Study of Steam Reforming of Methane

The paper introduces a mathematical model that describes the cavitation process occurring during the passage of a water steam flow in various geometric configurations of a hydrodynamic device. The flow experiences a localized constriction (convergent nozzle) followed by expansion (divergent nozzle), exemplified by a Venturi tube or a Laval nozzle. A narrow flow channel connecting the convergent and divergent sections is equipped with a narrow-section nozzle for injecting methane molecules into the high-speed steam flow. As the steam-gas mixture passes through this zone, it is irradiated with an electron beam and sprayed into a cylindrical chamber at atmospheric pressure, where the distribution of methane molecules in water vapor forms an aerosol. Key geometric parameters of the constriction and expansion zones of the hydraulic system (cavitation-jet chamber) are determined to ensure the uniform distribution of dispersed-phase particles (methane) in the dispersion medium (water vapor). Velocity and pressure distributions of the mixed steam-gas flow are calculated using a turbulent mathematical model, specifically the k-ω model, while the motion of methane particles is simulated using a particle tracing method. The uniformity of methane molecule distribution in water vapor is assessed using Ripley’s K-function. The best performance of the hydrogen-producing chamber was observed when the cavitation-inducing nozzle’s convergence angle exceeded 50 degrees. The divergence angle of the nozzle within the range of 30–40 degrees provided the best distribution in terms of uniformity of the methane particles in the chamber.

Identification of early opportunities for simultaneous H2 separation and CO2 storage using depleted coal seams

Hydrogen (H2) production by steam methane reforming (SMR) is an economically viable technique on a commercial scale. However, this process produces large amounts of carbon dioxide (CO2), which eventually negates the benefits of employing H2 as an industrial input and clean energy carrier. This issue has led to increasing interest in capturing CO2 emissions from SMR to produce H2. This study proposes and investigates the use of coalbed methane (CBM) resources for separating the mixture of H2 and CO2 gases. The competitive adsorption mechanism in CBM not only can separate the H2 gas from the mixture but also results into the geological storage of CO2 at the same time. The idea is to inject the mixture of H2 and CO2 into a depleted coal seam gas and produce gas from another well offset by a distance. This work studies the proposed idea using a multi-physics simulation model based on the available data in the literature. The model accounts for multicomponent, multi-phase flow, coal swelling/shrinkage, diffusion, and sorption. Several simulations were performed to investigate the feasibility of H2 separation and CO2 storage in CBM. Proof-of-concept simulations showed over 80% H2 separation and over 90% CO2 storage. This result shows that H2 separation and CO2 storage can be performed simultaneously with high efficiency.

Process Considerations for the Production of Hydrogen via Steam Reforming of Oxygenated Gases from Biomass Pyrolysis and Other Conversion Processes

AbstractIn 2021, average CO2 emissions was 9.7 g CO2/g H2 produced, primarily based on steam methane reforming (SMR) technology that currently dominates hydrogen production. The substitution of natural gas (NG) and other fossil feedstocks in SMRs with renewable gases may be considered as an option for reducing greenhouse gas emissions. This analysis explores process impacts and constraints associated with the potential introduction of biogenic gases into SMRs. The results indicate that replacing NG in the fuel train of the SMR, followed by partial replacement of NG in the feed train may be a feasible approach. For the CO‐ and CO2‐rich gas compositions assumed in this analysis the results indicate that feed train may accommodate up to 25 mole % of biogenic gases using allowances in existing designs and/or with small modifications, while maintaining similar hydrogen output. NG substitution in higher proportions require more major changes because of increased flow rates and heat exchange requirements in the system. Biogenic gases with lower CO2 and higher calorific values are advantageous for NG substitution, and dry reforming using the CO2 present in the feed gas can reduce steam consumption and increase process efficiency within limits where coking does not become a new constraint.

Proton-Conducting Ceramic Membranes for the Production of Hydrogen via Decarbonized Heat: Overview and Prospects

Proton-conducting ceramic membranes show high hydrogen ion conductivity in the temperature range of 300–700 °C. They are attracting significant attention due to their relevant characteristics compared to both higher-temperature oxygen ion-conducting ceramic membranes and lower-temperature proton-conducting polymers. The aim of this review is to integrate the fundamentals of proton-conducting ceramic membranes with two of their relevant applications, i.e., membrane reactors (PCMRs) for methane steam reforming (SMR) and electrolysis (PCEC). Both applications facilitate the production of pure H2 in the logic of process intensification via decarbonized heat. Firstly, an overview of various types of hydrogen production is given. The fundamentals of proton-conducting ceramic membranes and their applications in PCMRs for SMR and reversible PCEC (RePCEC), respectively, are given. In particular, RePCECs are of particular interest when renewable power generation exceeds demand because the excess electrical energy is converted to chemical energy in the electrolysis cell mode, therefore representing an appealing solution for energy conversion and grid-scale storage.

Calcium-based pellets for continuous hydrogen production by sorption-enhanced steam methane reforming

Sorption-enhanced steam methane reforming (SESMR) can produce high-purity H2 in one step, while removing CO2 to reduce carbon emissions. The sorbents, catalysts or bifunctional composite used in this system typically exist in powder form, which is difficult to use in industrialized fluidized bed reactors. Granulation can effectively avoid reactor clogging, increase practicality and operability of the system. In this work, Al-modified CaO-based sorbents were granulated using the graphite-casting method and test its sorption-enhanced hydrogen production effects during methane steam reforming. The effects of granulation on the microstructure, carbonation reactivity and mechanical properties were characterized. The reaction conditions (temperature and water-gas ratio) and the combination method of catalyst and sorbent (powder mixing, pellets mixing, layered placement and bifunctional materials mixed evenly at the molecular level) on hydrogen yield were investigated. Results showed that CaO-based pellets after granulation had a fluffy and porous structure, exhibited excellent adsorption performance under low CO2 partial pressure. The average crushing load of 75Ca25Al and 15Ni70Ca15Al pellets exceeded 6 N, showing good mechanical strength. The optimal reaction temperature range was found to be 550–600 °C. Increasing the water-gas ratio and reducing the flow rate were effective ways of improving CH4 conversion and H2 purity. The bifunctional 15Ni70Ca15Al powder prepared by sol-gel method had no catalytic effect on CH4–H2O reforming at 600 °C. After granulation, the catalytic performance was improved and the purity of H2 reached 95%, but it declined rapidly during multiple SESMR cycles. In the case of mixed of two pellets (catalyst and sorbent), the outlet H2 reached almost 100% with no decay observed over 15 cycles. When the switching time of feed gas was set to 60 min, high-purity (>96%) hydrogen can be produced continuously for 600 min on the parallel two fixed-bed reactors.

Electrification of steam cracking as a pathway to reduce the impact of the petrochemical industry on climate change

In the Chemical Process Industry (CPI) only hydrogen production from steam methane reforming produces more greenhouse gas emissions than light olefins production. Various solutions have been proposed to reduce the CO2 emissions from olefins production. It is not clear which solution is best, particularly when you consider other sustainability factors. In this paper we report the results of our cradle-to-gate life cycle assessment (LCA) of three highly promising solutions: a so-called low-emission steam cracking furnace, the electrically driven RotoDynamic reactor (RDR), and a blue hydrogen-fired furnace. Life cycle inventory data is obtained from a first principles model for steam cracking, validated with industrial data, and combined with data obtained from process simulation. Our study shows that if the electrical supply is grey then the RDR-based cracking process has a 41% higher impact on climate change than the reference base case, a conventional plant with state-of-the-art furnaces. The low-emission furnace is only 7.2% higher. When using a mixed electrical grid, like Belgium's, the climate change impact for the RDR is 1.5% higher and the low emission furnace is 6.6% lower. With a grid that uses fully renewable power generation the RDR solution is an impressive 27% lower than the base case and the low-emission furnace 17% lower. We also analysed the impact of firing the furnaces with blue hydrogen from (a) a conventional steam-methane reformer and (b) an innovative gas-heated reformer: both (a) and (b) using carbon capture and storage (CCS). The climate change impact is reduced by 8% and 18% respectively compared to the base case. Since the blue hydrogen solution uses very little electricity, the climate change impact is insensitive to the method of electrical power generation.

Exploring the Challenges of Calcium Looping Integrated with Methane Bireforming for Enhanced Carbon Capture and Utilization.

The urgent need to mitigate greenhouse gas emissions and combat climate change has driven research in carbon capture and utilization (CCU) technologies. Among these, calcium looping (CaL) has emerged as a prominent candidate for CO2 capture. This study aimed to explore the novel integration of CaL with methane bireforming (BRM) using CaO-Ni/CeO2 as dual-function material (DFM) and investigated the challenges and opportunities associated with the process. Implementing a calcium looping-bireforming (CaL-BRM) process revealed distinct differences compared to methane dry reforming (DRM). Notably, methane conversion occurred at higher temperatures, likely due to competition with the formation of Ca(OH)2. Meanwhile, the conversion of CO2 was delayed, possibly because hydroxide species on the CaO surfaces hindered the availability of CO2 for methane reforming. To address these challenges, Ni/CeO2 and CaO-Ni/CeO2 catalysts were employed in conventional catalytic gas-phase BRM and methane steam reforming (SRM) reactions. The results demonstrated that the presence of CaO significantly influenced BRM efficiency due to the Ca(OH)2 formation, as was evident by the results of the characterization on the postreaction catalysts and the parallel study of SRM. This study contributes valuable insights into the feasibility and potential of CaL-BRM, advancing the development of sustainable CCU technologies.

Metallic Honeycomb Catalysts for Methane Steam Reforming: Effect of the Bimetallic Surface Coating on Catalytic Properties

Metallic honeycomb catalysts are promising candidates for fuel cell and small-scale onsite hydrogen production applications. In this study, high-cell-density Ni honeycomb catalysts coated with a series of bimetallic surface layers were synthesized. Their catalytic performance for CH4 steam reforming was investigated under a low steam-to-carbon ratio of 1.36 and a gas hourly space velocity of 6400 h-1 in the temperature range of 400–700°C. The catalysts coated with Ni-Mg and Ni-Zr showed excellent catalytic performance, reaching a high CH4 conversion and CO selectivity close to the equilibrium values within the test temperature range. The enhanced catalytic performance of the Ni-Mg and Ni-Zr coatings was attributed to the formation of oxide-supported fine Ni particles. In contrast, the catalysts coated with Ni-Fe and Ni-Sn exhibited an extremely low activity, which was lower than that of the catalyst coated with only Ni. The low activity of the Ni-Fe and Ni-Sn coatings is supposed to be due to the formation of aggregated Ni3Fe, Ni3Sn, and Ni3Sn2 phases.

Multi-objective optimization of breakthrough times for hydrogen purification through layered bed pressure swing adsorption based on genetic algorithm and artificial neural network model

Hydrogen purification from steam methane reforming (SMR) by pressure swing adsorption (PSA) technology is a common method to obtain high-purity hydrogen. The breakthrough time can well reflect the adsorption dynamics and help PSA cycle design. In order to avoid time-consuming and labor-intensive breakthrough curve experiments, it is very necessary to develop a fast and accurate surrogate model. In this study, a genetic algorithm (GA) and artificial neural network (ANN) are combined to predict and optimize breakthrough times of adsorbates in activated carbon/zeolite layered beds. Using the Latin hypercube sampling strategy, training data sets of GA-optimized ANN (GA-ANN) obtains from the physical model of adsorption, heat and mass transfer model. The genetic algorithm (GA) optimizes the weights and biases of ANN for better performance. The ANN topology has 4 input variables (superficial velocity, activated carbon height, adsorption pressure and feed temperature) and 3 output variables (breakthrough times of CH4, CO and CO2). The number of neurons in the hidden layer for the GA-ANN model was optimized as 7 to predict and optimize the maximum breakthrough time of SMR with a four-component (H2/CH4/CO/CO2) system. The sensitivity analysis displays that relative importance to the breakthrough time is in the order of superficial velocity (40.88%) > adsorption pressure (24.55%) > activated carbon height (21.04%) > feed temperature (13.53%). To obtain high-purity hydrogen, the GA-ANN model combined with multi-objective GA optimization is used to maximize the breakthrough times of CH4 and CO. The GA-ANN surrogate model proposed in this paper can not only accurately and quickly achieve the purpose of predicting the system breakthrough time with a high correlation coefficient (R = 0.9937) but also obtains the optimal operating conditions of PSA hydrogen purification.

Experimental investigation and 2D mathematical modelling of copper foams packed with Rh-Al2O3 catalysts for the intensification of methane steam reforming

Efficient heat transfer is a crucial factor in the design of compact methane steam reformers for delocalized hydrogen production. The use of copper packed foams was proposed few years ago by our group to strongly intensify heat transfer in these systems, allowing the design of small-scale units with minimal radial temperature gradients. In this study, a new experimental campaign was performed to demonstrate the concept potential under industrially relevant heat fluxes and to establish an experimental foundation for validating a 2D mathematical model of the process. Copper open-cell foams were packed with a Rh/Al2O3 egg-shell catalyst and loaded into a 29.5 mm diameter tubular reactor, which was heated using a lab-scale oven. By leveraging the combined benefits of enhanced heat transfer, granted by the copper foam, and the high activity of the Rh-based eggshell catalyst, experiments were successfully performed at gas hourly space velocities (GHSV) ranging from 10 to 30 Nm3/h/kgcat, with heat duties of up to 9 MW/m3. These experiments lead to a methane conversion close to thermodynamic equilibrium while maintaining limited radial gradients within the system (maximum 20 °C across the mid-radius). A predictive pseudo-heterogeneous 2D reactor model was developed and validated against experimental data. The model accurately captured the observed trends in temperature profiles and outlet concentrations, and can be utilized for optimized design, paving the way for the development of efficient small-scale hydrogen production units.

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.

Comparison of mathematical models of steam methane reforming process for the needs of fuel cells

The article presents a comparison of mathematical models of steam methane reforming. The analysis is divided into two parts. The first concerns the reforming process using separate steam reformers. The second part of the article compares models of steam methane reforming processes directly inside fuel cells. Due to the fact that the steam reforming process takes place at very high temperatures, internal steam reforming can only be carried out in high temperature fuel cells. Therefore, the second part of the article deals with molten carbonate fuel cells and solid oxide fuel cells powered by methane. In the case of both of fuel cells, the methane steam reforming may take place directly on the anodes of these electrochemical devices. The mathematical models (for both external and internal reforming) were compared based on available experimental data. In this analysis of mathematical models, particular attention was paid to the causes of discrepancies between the mathematical models and the experimental data. The steam reforming process is influenced by a number of different parameters such as: temperature, ratio of the amount of water vapor to carbon contained in the fuel (steam to carbon ratio), reaction time, presence of a catalyst, type of catalyst and many others. The models presented in this article were also compared in terms of taking into account various parameters that may affect the process of steam reforming. An attempt was also made to assess the accuracy of mathematical models. Unfortunately, for most of the equations considered in this article, numerical values for inaccuracies are not given or described as acceptable or minor.