Search Results (250)

Hydrogen production is increasingly vital for global decarbonization but remains a water- and energy-intensive process, especially in arid regions. Despite growing attention to its climate benefits, limited research has addressed the environmental impacts of water sourcing. This study employs a life cycle assessment (LCA) approach to evaluate three water supply strategies for hydrogen production: (1) seawater desalination without brine treatment (BT), (2) desalination with partial BT, and (3) freshwater purification. Scenarios are modeled for the United Arab Emirates (UAE), Australia, and Spain, representing diverse electricity mixes and water stress conditions. Both electrolysis and steam methane reforming (SMR) are evaluated as hydrogen production methods. Results show that desalination scenarios contribute substantially to human health and ecosystem impacts due to high energy use and brine discharge. Although partial BT aims to reduce direct marine discharge impacts, its substantial energy demand can offset these benefits by increasing other environmental burdens, such as marine eutrophication, especially in regions reliant on carbon-intensive electricity grids. Freshwater scenarios offer lower environmental impact overall but raise water availability concerns. Across all regions, feedwater for SMR shows nearly 50% lower impacts than for electrolysis. This study focuses solely on the environmental impacts associated with water sourcing and treatment for hydrogen production, excluding the downstream impacts of the hydrogen generation process itself. This study highlights the trade-offs between water sourcing, brine treatment, and freshwater purification for hydrogen production, offering insights for optimizing sustainable hydrogen systems in water-stressed regions. Full article

This review explores CO₂ methanation and steam methane reforming (SMR) as two key thermochemical processes governed by reversible reactions, each offering distinct contributions to carbon-neutral energy systems. The objective is to provide a comparative assessment of both processes, highlighting how reaction reversibility can be strategically leveraged for decarbonization. The study addresses methane production via CO₂ methanation and hydrogen production via SMR, focusing on their thermodynamic behaviors, catalytic systems, environmental impacts, and economic viability. CO₂ methanation, when powered by renewable hydrogen, can result in emissions ranging from −471 to 1076 kg CO₂-equivalent per MWh of methane produced, while hydrogen produced from SMR ranges from 90.9 to 750.75 kg CO₂-equivalent per MWh. Despite SMR’s lower production costs (USD 21–69/MWh), its environmental footprint is considerably higher. In contrast, methanation offers environmental benefits but remains economically uncompetitive (EUR 93.53–204.62/MWh). Both processes rely primarily on Ni-based catalysts, though recent developments in Ru-based and bimetallic systems have demonstrated improved performance. The review also examines operational challenges such as carbon deposition and catalyst deactivation. By framing these technologies through the shared lens of reversibility, this work outlines pathways toward integrated, efficient, and circular energy systems aligned with long-term sustainability and climate neutrality goals. Full article

During the steam reforming of methane (SRM) process, elevated CH₄ levels after the reaction often signify inadequate heat supply or incomplete reactions within the reformer, jeopardizing process stability. In this paper, a novel multi-step forecasting method using a Trans-GRU network was proposed for predicting the methane content outlet of the SRM reformer. First, a novel feature selection based on the maximal information coefficient (MIC) was applied to identify critical input variables and determine their optimal input order. Additionally, the Trans-GRU network enables the simultaneous capture of multivariate correlations and the learning of global sequence representations. The experimental results based on time-series data from a real SRM process demonstrate that the proposed approach significantly improves the accuracy of multi-step methane content prediction. Compared to benchmark models, including the TCN, Transformer, GRU, and CNN-LSTM, the Trans-GRU consistently achieves the lowest root mean squared error (RMSE) and mean absolute error (MAE) values across all prediction steps (1–6). Specifically, at the one-step horizon, it yields an RMSE of 0.0120 and an MAE of 0.0094. This high performance remains robust across the 2–6-step predictions. The improved predictive capability supports the stable operation and predictive optimization strategies of the steam reforming process in hydrogen production. Full article

The increasing demand for hydrogen has made it a promising alternative for decarbonizing industries and reducing CO₂ emissions. Although mainly produced through the gray pathway, the integration of carbon capture and storage (CCS) reduces the CO₂ emissions. This study presents a sustainability method that uses flare gas for hydrogen production through steam methane reforming (SMR) with CCS, supported by a techno-economic analysis. Data Envelopment Analysis (DEA) was used to evaluate the oil company’s efficiency, and inverse DEA/sensitivity analysis identified maximum flare gas reduction, which was modeled in Aspen HYSYS V14. Subsequently, an economic evaluation was performed to determine the levelized cost of hydrogen (LCOH) and the cost–benefit ratio (CBR) for Nigeria. The CBR results were 2.15 (payback of 4.11 years with carbon credit) and 1.96 (payback of 4.55 years without carbon credit), indicating strong economic feasibility. These findings promote a practical approach for waste reduction, aiding Nigeria’s transition to a circular, low-carbon economy, and demonstrate a positive relationship between lean and green strategies in the petroleum sector. Full article

This work deals with the catalytic steam reforming of raw syngas to increase the efficiency of coupling gasification with downstream processes (such as fuel cells and catalytic chemical syntheses) by producing high-temperature, ready-to-use syngas without cooling it for cleaning and conditioning. Such a combination is considered a key point for the future exploitation of syngas produced by steam gasification of biogenic solid fuel. The design and construction of an integrated gasification and gas conditioning system were proposed approximately 20 years ago; however, they still require further in-depth study for practical applications. A 3D model of the freeboard of a pilot-scale, fluidized bed gasification plant equipped with catalytic ceramic candles was used to investigate the optimal operating conditions for in situ syngas upgrading. The global kinetic parameters for methane and tar reforming reactions were determined experimentally. A fluidized bed gasification reactor (~5 kWth) equipped with a 45 cm long segment of a fully commercial filter candle in its freeboard was used for a series of tests at different temperatures. Using a computational fluid dynamics (CFD) description, the relevant parameters for apparent kinetic equations were obtained in the frame of a first-order reaction model to describe the steam reforming of key tar species. As a further step, a CFD model of the freeboard of a 100 kWth gasification plant, equipped with six catalytic ceramic candles, was developed in ANSYS FLUENT^®. The composition of the syngas input into the gasifier freeboard was obtained from experimental results based on the pilot-scale plant. Simulations showed tar catalytic conversions of 80% for toluene and 41% for naphthalene, still insufficient compared to the threshold limits required for operating solid oxide fuel cells (SOFCs). An overly low freeboard temperature level was identified as the bottleneck for enhancing gas catalytic conversions, so further simulations were performed by injecting an auxiliary stream of O₂/steam (50/50 wt.%) through a series of nozzles at different heights. The best simulation results were obtained when the O₂/steam stream was fed entirely at the bottom of the freeboard, achieving temperatures high enough to achieve a tar content below the safe operating conditions for SOFCs, with minimal loss of hydrogen content or LHV in the fuel gas. Full article

The dry reforming of methane (DRM) and the combined steam–CO₂ reforming of methane (CSCRM) are promising routes for syngas production while simultaneously utilizing two major greenhouse gases—CO₂ and CH₄. In this study, a series of Ni/MgO-Al₂O₃ catalysts with varying Mg/Al molar ratios (Ni/MgAl(x), x = 0.5–0.9), along with Ni/MgO and Ni/Al₂O₃, were synthesized, characterized, and evaluated in both the DRM and CSCRM. Ni/MgO and Ni/Al₂O₃ exhibited a lower activity due to fewer active sites and a poor CH₄/CO₂ activation balance. In contrast, Ni/MgAl(0.6), Ni/MgAl(0.7), and Ni/MgAl(0.8) showed an enhanced activity, attributed to more abundant active sites and a more balanced activation of CH₄ and CO₂. Ni/MgAl(0.7) delivered the best DRM performance, whereas Ni/MgAl(0.8) was optimal for the CSCRM, likely due to its greater number of strong basic sites promoting CO₂ and H₂O adsorption. At 750 °C and 0.1 MPa over 100 h, Ni/MgAl(0.7) maintained a stable DRM performance (77% CH₄ and 86% CO₂ conversion; H₂/CO = 0.9) at 120 L/(g_cat·h), while Ni/MgAl(0.8) achieved a stable CSCRM performance (80% CH₄ and 62% CO₂ conversion; H₂/CO = 2.1) at 132 L/(g_cat·h). This study provides valuable insights into designing efficient Ni/MgO-Al₂O₃ catalysts for targeted syngas production. Full article

Solid oxide fuel cells (SOFCs) represent a pivotal technology in renewable energy due to their clean and efficient power generation capabilities. Their role in potential carbon mitigation enhances their viability. SOFCs can operate via a variety of alternative fuels, including hydrocarbons, alcohols, solid carbon, and ammonia. However, several solutions have been proposed to overcome various technical issues and to allow for stable operation in dry methane, without coking in the anode layer. To avoid coke formation thermodynamically, methane is typically reformed, contributing to an increased degradation rate through the addition of oxygen-containing gases into the fuel gas to increase the O/C ratio. The performance achieved by reforming catalytic materials, comprising active sites, supports, and electrochemical testing, significantly influences catalyst performance, showing relatively high open-circuit voltages and coking-resistance of the CH₄ reforming catalysts. In the next step, the operating principles and thermodynamics of methane reforming are explored, including their traditional catalyst materials and their accompanying challenges. This work explores the components and functions of SOFCs, particularly focusing on anode materials such as perovskites, Ruddlesden–Popper oxides, and spinels, along with their structure–property relationships, including their ionic and electronic conductivity, thermal expansion coefficients, and acidity/basicity. Mechanistic and kinetic studies of common reforming processes, including steam reforming, partial oxidation, CO₂ reforming, and the mixed steam and dry reforming of methane, are analyzed. Furthermore, this review examines catalyst deactivation mechanisms, specifically carbon and metal sulfide formation, and the performance of methane reforming and partial oxidation catalysts in SOFCs. Single-cell performance, including that of various perovskite and related oxides, activity/stability enhancement by infiltration, and the simulation and modeling of electrochemical performance, is discussed. This review also addresses research challenges in regards to methane reforming and partial oxidation within SOFCs, such as gas composition changes and large thermal gradients in stack systems. Finally, this review investigates the modeling of catalytic and non-catalytic processes using different dimension and segment simulations of steam methane reforming, presenting new engineering designs, material developments, and the latest knowledge to guide the development of and the driving force behind an oxygen concentration gradient through the external circuit to the cathode. Full article

In this work, Aspen Plus was used to simulate a sorption-enhanced steam methane reforming (SE-SMR) process in a fluidized bed reformer using a Ni-based catalyst and CaO as a sorbent for CO₂ removal from the reaction environment. The performances of the process in terms of the outlet gas hydrogen purity (y_H2), methane conversion (X_CH4), and hydrogen yield (η_H2) were investigated. The process was simulated by varying the following different reformer operating parameters: pressure, temperature, steam/methane (S/C) feed ratio, and CaO/CH₄ feed ratio. A clear sorption-enhanced effect occurred, where CaO was fed to the reformer, compared with traditional SMR, resulting in improvements of y_H2, X_CH4, and η_H2. This effect, in percentage terms, was more relevant, as expected, in conditions where the traditional process was unfavorable at higher pressures. The presence of CaO could only partially balance the negative effect of a pressure increase. This partial compensation of the negative pressure effect demonstrated that the intensification process has the potential to produce blue hydrogen while allowing for less severe operating conditions. Indeed, when moving traditional SMR from 1 to 10 bar, an average decrease of y_H2, X, and η by −16%, −44%, and −41%, respectively, was recorded, while when moving from 1 bar SMR to 10 bar SE-SMR, y_H2 showed an increase of +20%, while X_CH4 and η_H2 still showed a decrease of −14% and −4%. Full article

Biogas is a crucial renewable energy source for green hydrogen (H₂) production, reducing greenhouse gas emissions and serving as a carbon-free energy carrier with higher specific energy than traditional fuels. Currently, methane reforming dominates H₂ production to meet growing global demand, with biogas/landfill gas (LFG) reform offering a promising alternative. This study provides a comprehensive simulation-based evaluation of Steam Methane Reforming (SMR) and Dry Methane Reforming (DMR) of biogas/LFG, using Aspen Plus. Simulations were conducted under varying operating conditions, including steam-to-carbon (S/C) for SMR and steam-to-carbon monoxide (S/CO) ratios for DMR, reforming temperatures, pressures, and LFG compositions, to optimize H₂ yield and process efficiency. The comparative study showed that SMR attains higher specific H₂ yields (0.14–0.19 kgH₂/Nm³), with specific energy consumption between 0.048 and 0.075 MWh/kg of H₂, especially at increased S/C ratios. DMR produces less H₂ than SMR (0.104–0.136 kg H₂/Nm³) and requires higher energy inputs (0.072–0.079 MWh/kg H₂), making it less efficient. Both processes require an additional 1.4–2.1 Nm³ of biogas/LFG per Nm³ of feed for energy. These findings provide key insights for improving biogas-based H₂ production for sustainable energy, with future work focusing on techno–economic and environmental assessments to evaluate its feasibility, scalability, and industrial application. Full article

The global campaign to reach net zero will necessitate the use of hydrogen as an efficient way to store renewable electricity at large scale. Methane pyrolysis is rapidly gaining traction as an enabling technology to produce low-cost hydrogen without directly emitting carbon dioxide. It offers a scalable and sustainable alternative to steam reforming whilst being compatible with existing infrastructure. The process most commonly uses thermal energy to decompose methane (CH₄) into hydrogen gas (H₂) and solid carbon (C). The electrification of this reaction is of great significance, allowing it to be driven by excess renewable electricity rather than fossil fuels, and eliminating indirect emissions. This review discusses the most recent technological advances in electrified methane pyrolysis and the relative merits of the mainstream reactor technologies in this space (plasma, microwave, fluidised bed, and direct resistive heating). This study also examines the economic viability of the process, considering energy costs, and the market potential of both turquoise hydrogen and solid carbon products. Whilst these technologies offer emission-free hydrogen production, challenges such as carbon deposition, reactor stability, and high energy consumption must be addressed for large-scale adoption. Future research should focus on process optimisation, advanced reactor designs, and policy frameworks to support commercialisation. With continued technological innovation and sufficient investment, electrified methane pyrolysis has the potential to become the primary route for sustainable production of hydrogen at industrial scale. Full article

This study investigates the effect of potassium (K) promotion on Pt/m-ZrO₂ catalysts in methanol steam reforming (MSR), revealing critical insights into reaction pathways and catalyst performance. While increasing K loading reduces catalytic activity, it selectively enhances the hydrogen-producing formate dehydrogenation and de-carboxylation pathway. Structural analyses using HR-TEM and DRIFTS show that higher K concentrations block Pt sites and promote agglomeration, reshaping catalytic behavior. Notably, the 3.1% K-promoted catalyst achieves high stability at 358 °C, with a CO₂ selectivity exceeding 80% and minimal methane formation, outperforming the unpromoted catalyst in terms of CO and CH₄ selectivity. Temperature studies further demonstrate reduced CO selectivity at higher temperatures, highlighting distinct advantages of K-doped catalysts. These findings underscore the role of K in enhancing surface basicity and its impact on formate interaction, offering valuable insights for optimizing MSR catalysts and advancing hydrogen production technologies. Full article

A thermodynamic analysis of a compact hydrogen generation system for mobile fuel cell applications is presented. The system consists of a miniature autothermal steam reformer (ATR) and a water–gas shift (WGS) reactor, designed to produce hydrogen from hydrocarbon fuels for a 1 kW proton exchange membrane (PEM) fuel cell. Methane is used as the model fuel, and the study focuses on optimizing feed compositions and operational conditions to maximize hydrogen yield and purity. Feed compositions and operational conditions are optimized. In total, 0.7 Nm³ h⁻¹ H₂ is generated from 0.25 Nm³ h⁻¹ CH₄ with properly adjusted steam and air feeding. Issues with product purity and start-up procedures have been identified and discussed, along with feasible solutions. The system is suitable for remote and mobile applications. Full article

The topic of hydrogen as an energy vector is widely discussed in the present literature, being one of the crucial technologies aimed at human carbon footprint reduction. There are different hydrogen production methods. In particular, this paper focuses on Steam Methane Reforming (SMR), which requires a source of high-temperature heat (around 900 °C) to trigger the chemical reaction between steam and CH₄. This paper examines a plant in which the reforming heat is supplied through a helium-cooled high-temperature nuclear reactor (HTR). After a review of the recent literature, this paper provides a description of the plant and its main components, with a central focus on the safety and reliability features of the combined nuclear and chemical system. The main aspect emphasized in this paper is the assessment of the hydrogen production reliability, carried out through Failure Modes and Effects Analysis (FMEA) with the aid of simulation software able to determine the quantity and origin of plant stops based on its operational tree. The analysis covers a time span of 20 years, and the results provide a breakdown of all the failures that occurred, together with proposals aimed at improving reliability. Full article

The LNG maritime industry started to anticipate offshore LNG production in tandem with increasing demand for FLNG platforms as offshore gas resources were developed further. The rapid expansion of FLNG deployment demands equipment and procedures that handle challenges associated with weight and space constraints. The chemical composition of LNG will result in slightly fewer CO₂ emissions. While not significant, another crucial aspect is that LNG predominantly comprises methane, which is acknowledged as a greenhouse gas and is more harmful than CO₂. This requires investigation into clean energy fuel supply for power generation systems, carbon emissions from the process, and thermodynamic analysis and optimisation. Focus on supplying fuel for FLNG power generation to reduce the essential management of boil-off fuel gas, which can be researched on the direct reforming method of hydrogen as a marine fuel gas to support the power generation system. The principal reason for choosing hydrogen over other energy sources is its exceptional energy-to-mass ratio (H/C ratio). The most effective method for hydrogen production is the methane reforming process, recognised for generating significant quantities of hydrogen. To optimise the small-scale plant with a carbon capture system (CCS) as integrated into the reforming process to produce blue hydrogen fuel with zero carbon emissions, this research selection focuses on two alternative processes: steam methane reforming (SMR) and autothermal reforming (ATR). Furthermore, the research article will contribute to other floating production platforms, such as FPSOs and FSRUs, and will be committed to clean energy policies that mandate the support of green alternatives in substitution of hydrocarbon fuel utilisation. Full article

Biogas (primarily biomethane), as a carbon-neutral renewable energy source, holds great potential to replace fossil fuels for sustainable hydrogen production. Conventional biogas reforming systems adopt strategies similar to industrial natural gas reforming, posing challenges such as high temperatures, high energy consumption, and high system complexity. In this study, we propose a novel multi-product sequential separation-enhanced reforming method for biogas-derived hydrogen production, which achieves high H₂ yield and CO₂ capture under mid-temperature conditions. The effects of reaction temperature, steam-to-methane ratio, and CO₂/CH₄ molar ratio on key performance metrics including biomethane conversion and hydrogen production are investigated. At a moderate reforming temperature of 425 °C and pressure of 0.1 MPa, the conversion rate of CH₄ in biogas reaches 97.1%, the high-purity hydrogen production attains 2.15 mol-H₂/mol-feed, and the hydrogen yield is 90.1%. Additionally, the first-law energy conversion efficiency from biogas to hydrogen reaches 65.6%, which is 11 percentage points higher than that of conventional biogas reforming methods. The yield of captured CO₂ reaches 1.88 kg-CO₂/m³-feed, effectively achieving near-complete recovery of green CO₂ from biogas. The mild reaction conditions allow for a flexible integration with industrial waste heat or a wide selection of other renewable energy sources (e.g., solar heat), facilitating distributed and carbon-negative hydrogen production. Full article