Hydrogen Production Applications Research Articles

Enhancing Photocatalytic Activities for Sustainable Hydrogen Evolution on Structurally Matched CuInS2/ZnIn2S4 Heterojunctions

Effective charge separation and migration pose a critical challenge in the field of solar-driven hydrogen production. In this work, a Z-scheme structured CuInS2/ZnIn2S4 heterojunction was successfully fabricated through a two-step hydrothermal synthesis method to significantly enhance the efficiency of solar-to-hydrogen energy conversion. Structural characterization revealed that the lattice-matched CuInS2/ZnIn2S4 heterojunction exhibits an enlarged interfacial contact area, which facilitates the transfer and separation of photogenerated charges. Microscopic analysis indicated that the CuInS2/ZnIn2S4 composite material has a tightly interwoven interface and a morphology resembling small sugar cubes. Photoelectrochemical spectroscopy analysis demonstrated that the heterojunction structure effectively enhances visible light absorption and charge separation efficiency, leading to an improvement in photocatalytic activity. Hydrogen production experimental data indicated that the CuInS2/ZnIn2S4 heterojunction photocatalyst prepared with a CuInS2 content of 20 wt% exhibits the highest hydrogen evolution rate, reaching 284.9 μmol·g−1·h−1. Moreover, this photocatalyst maintains robust photocatalytic stability even after three consecutive usage cycles. This study demonstrated that the Z-scheme CuInS2/ZnIn2S4 heterojunction photocatalyst exhibits enhanced hydrogen evolution efficiency, offering an effective structural design for harnessing solar energy to obtain hydrogen fuel. Therefore, this heterojunction photocatalyst is a promising candidate for practical applications in solar hydrogen production.

Aqueous Room‐Temperature Synthesis of Transition Metal Dichalcogenide Nanoparticles: A Sustainable Route to Efficient Hydrogen Evolution

AbstractTransition metal dichalcogenides (TMDs) have emerged as a focal point in electrocatalysis, particularly for the hydrogen evolution reaction (HER), owing to their notable catalytic activity, chemical stability, and cost‐efficiency. Despite these advantages, the challenge of devising a practical and economical method for their large‐scale application in HER remains an unresolved and critical issue. In this study, a facile, scalable, and cost‐effective approach is introduced for producing high‐yield, catalytically active TMD nanoparticles, including MoS2, MoSe2, RuS2, and RuSe2. These nanoparticles are synthesized through an aqueous room‐temperature process, which is not only environmentally friendly but also economically feasible for large‐scale production. Remarkably, these TMD nanoparticles exhibit versatile catalytic activity across a broad pH range for HER. Among them, RuSe2 nanoparticles demonstrate catalytic performance comparable to that of a commercial Pt/C electrode. Upon scaling up, the nanomaterials show great potential for integration into practical proton exchange membrane water electrolyzers, maintaining high efficiency even at large current densities and exhibiting very stable performance for up to 100 h. This research paves the way to a sustainable synthesis method of high‐performance catalysts, tailored for industrial hydrogen production applications.

A Remarkable Pt Doped CNT Catalyst as a Double Functional Material: Its Application for Hydrogen Production and Supercapacitor

In this study, by producing bifunctional material, hydrolysis, and supercapacitor applications were investigated. The carbon nanotube-supported Pt catalyst was prepared using the sodium borohydride (NaBH<sub>4</sub>) reduction. Surface characterization of the synthesized Pt/CNT catalyst was performed using scanning electron microscopy-energy dıstrıbutıon X-ray spectrometer (SEM-EDX), X-ray diffraction (XRD), and transmission electron microscopy (TEM). Hydrolysis experiments were performed after deciding on the appropriate atomic ratio from the Pt/CNT catalysts synthesized in different nuclear ratios. The parameters affecting the hydrogen production from NaBH<sub>4</sub> were examined. As a result of the kinetic calculations, the initial rates of reaction for 30°C and 60°C were calculated as 21949,69 mlH<sub>2</sub>g<sub>cat</sub>min<sup>-1</sup> and 70018,18 mlH<sub>2</sub>g<sub>cat</sub>min<sup>-1</sup>. Galvastonic charge-discharge (GCD), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) were used as characterization techniques for the use of Pt/CNT catalysts as electrodes in supercapacitor applications. The specific capacitance value of 7% Pt/CNT catalyst at 1 A/g current density was calculated as 57,78 F/g. Energy and power density were calculated as 8,025 Wh/kg and 963 W/kg, respectively. Therefore, this catalyst is called a “cap-cat” with capacitor properties. The catalyst used in this study is promising for this recently studied topic.

Heterogeneous Ni-Boride/Phosphide Anchored Amorphous B-C Layer for Overall Water Electrocatalysis.

The rational design of efficient and economical bifunctional electrocatalysts remained a challenge for overall water electrolysis. In this work, the Ni-boride/ phosphide particles anchored amorphous B-doped carbon layer with hierarchical porous characteristics in Ni foam (Ni3P/Ni3B/B-C/NF) was fabricated for overall water splitting. The Boroncarbide (B4C) power was filled and fixed in the NF interspace through the electroplating and electroless plating, and then annealed in vacuum high temperature. The amorphous B-C layer derived from the B4 C not only speeded up the electron transport, but also cooperate with Ni-boride/phosphide to enhance the electrocatalytic activity for HER and OER synergistically. Furthermore, the hierarchical porous architecture of Ni3P/Ni3B/B-C/NF increased space utilization to load more active materials. The self-supported Ni3P/Ni3B/B-C/NF electrode possessed a low overpotential of 212 and 280 mV to deliver 100 mA cm-2 for HER and OER, respectively, and high stability for 48 h. In particular, the electrolyzer constituted with the Ni3P/Ni3B/B-C/NF bifunctional electrocatalyst only required a voltage of 1.59 V at 50 mA cm-2 for water electrocatalysis under alkaline medium, and demonstrated long-term stability for 48 h. This study provides a new technical path for the development of bifunctional of transition metal borides to promote the application of hydrogen production from water splitting.

Hydrothermally Synthesized ZnCr- and NiCr-Layered Double Hydroxides as Hydrogen Evolution Photocatalysts.

The layered double hydroxides (LDHs) of transition metals are of great interest as building blocks for the creation of composite photocatalytic materials for hydrogen production, environmental remediation and other applications. However, the synthesis of most LDHs is reported only by the conventional coprecipitation method, which makes it difficult to control the catalyst's crystallinity. In the present study, ZnCr- and NiCr-LDHs have been successfully prepared using a facile hydrothermal approach. Varying the hydrothermal synthesis conditions allowed us to obtain target products with a controllable crystallite size in the range of 2-26 nm and a specific surface area of 45-83 m2∙g-1. The LDHs synthesized were investigated as photocatalysts of hydrogen generation from aqueous methanol. It was revealed that the photocatalytic activity of ZnCr-LDH samples grows monotonically with the increase in their average crystallite size, while that of NiCr-LDH ones reaches a maximum with intermediate-sized crystallites and then decreases due to the specific surface area reduction. The concentration dependence of the hydrogen evolution activity is generally consistent with the standard Langmuir-Hinshelwood model for heterogeneous catalysis. At a methanol content of 50 mol. %, the rate of hydrogen generation over ZnCr- and NiCr-LDHs reaches 88 and 41 μmol∙h-1∙g-1, respectively. The hydrothermally synthesized LDHs with enhanced crystallinity may be of interest for further fabrication of their nanosheets being promising components of new composite photocatalysts.

Preparation and Spectrochemical characterization of Ni-doped ZnS nanocomposite for effective removal of emerging contaminants and hydrogen Production: Reaction Kinetics, mechanistic insights

In this study, we report the successful synthesis of Ni-doped ZnS nanocomposite via a green route using ethanolic crude extract of Avena fatua. The as-synthesized nanocomposite was comprehensively characterized using Dynamic light scattering (DLS), Zeta potential, scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and Atomic force microscopy (AFM). These analyses provided detailed insights into the size, morphology, composition, surface properties, and structural characteristics of the nanocomposite. Subsequently, the synthesized nanocomposite was evaluated for their photocatalytic performance against the organic dye Methyl orange. Remarkably, the nanocomposite exhibited rapid and efficient degradation of Methyl orange, achieving 90 % degradation within only 30 min of irradiation under UV light. Moreover, the photocatalyst demonstrated an exceptional hydrogen production rate, reaching 167.73 µmolg-1h−1, which is approximately 4.5 times higher than that of its pristine counterparts. These findings highlight the significant potential of Ni-doped ZnS nanocomposite as highly efficient photocatalysts for wastewater treatment and hydrogen production applications.

Ultrasonic-Assisted Electrodeposition of Mn-Doped NiCo2O4 for Enhanced Photodegradation of Methyl Red, Hydrogen Production, and Supercapacitor Applications

This paper presents a novel ultrasonic-assisted electrodeposition process of Mn-doped NiCo2O4 onto a commercial nickel foam in a neutral electroplating bath (pH = 7.0) under an ultrasonic power of 1.2 V and 100 W. Different sample properties were studied based on their crystallinity through X-ray diffraction (XRD), morphology was studied through scanning electron microscopy (SEM), and photodegradation was studied through ultraviolet–visible (UV–Vis) spectrophotometry. Based on the XRD results, the dominant crystallite phase obtained was shown to be a pure single NiCo2O4 phase. The optical properties of the photocatalytic film showed a range of energy band gaps between 1.72 and 1.73 eV from the absorption spectrum. The surface hydroxyl groups on the catalytic surface of the Mn-doped NiCo2O4 thin films showed significant improvements in removing methyl red via photodegradation, achieving 88% degradation in 60 min, which was approximately 1.6 times higher than that of pure NiCo2O4 thin films. The maximum hydrogen rate of the composite films under 100 mW/cm2 illumination was 38 μmol/cm2 with a +3.5 V external potential. The electrochemical performance test also showed a high capacity retention rate (96% after 5000 charge–discharge cycles), high capacity (260 Fg−1), and low intrinsic resistance (0.8 Ω). This work concludes that the Mn-doped NiCo2O4 hybrid with oxygen-poor conditions (oxygen vacancies) is a promising composite electrode candidate for methyl red removal, hydrogen evolution, and high-performance hybrid supercapacitor applications.

Application and Challenge of Cadmium Sulfide Photocatalytic Hydrogen Production in Artificial Photosynthesis

Application and Challenge of Cadmium Sulfide Photocatalytic Hydrogen Production in Artificial Photosynthesis

Enhanced Electrochemical Catalysis: Hydrogen Evolution Using Bimetallic Sulfides on Nickel Foam.

Hydrogen is considered clean energy with broad application prospects for the 21st century, and water electrolysis plays a crucial role in hydrogen production. However, economic limitations and large overpotential values hinder its development. In this study, we deposited nickel (Ni), iron (Fe), and sulfur (S) onto nickel foam (NF) using the constant potential method to form the Ni-S-Fe/NF catalyst, which exhibited an exceptionally low overpotential (31 mV) at a current density of -10 mA cm-2, and a Tafel slope of 75.1 mV dec-1 in 1 M sodium hydroxide. It showed a minor charge resistance (1.256 Ω). The amorphous phase structure and optimized catalyst composition promoted outstanding hydrogen evolution activity. This work offers valuable perspectives on the industrial application of hydrogen production.

Numerical assessment and optimization of photovoltaic-based hydrogen-oxygen Co-production energy system: A machine learning and multi-objective strategy

Green hydrogen production technology based on photovoltaic (PV), battery energy storage system (BESS) and proton exchange membrane (PEM) water electrolysis plays a crucial part in the transition process of energy to zero carbon technology. But few studies have focused on achieving all-day continuous hydrogen production, which is the key to large-scale hydrogen utilization. In this study, we developed an off-grid PV-BESS-PEM system for hydrogen and oxygen production. Firstly, the PV, BESS and PEM water electrolysis components were modeled and model validation was performed. Secondly, an energy management strategy (EMS) is proposed to achieve the goal of continuous and stable hydrogen production. Then, a surrogate model between design variables and optimization objectives is established based on machine learning methods, and a multi-objective optimization algorithm is used to drive the optimization process. Finally, a case study of the PV-BESS-PEM system is presented based on solar irradiation data in Lhasa, where there is sufficient solar resources and oxygen demand. The results demonstrate that the EMS can satisfy the purpose of all-day continuous and stable hydrogen production. The number of cells in the electrolyzer and the water temperature have a significant effect on the hydrogen production and the electrolysis efficiency. And the optimal system has increased the hydrogen production by 16.80 % and the electrolysis efficiency of PEM by 12.08 %, respectively. Herein, the methodological framework is expected to provide theoretical guidance for large-scale water electrolysis hydrogen production applications based on solar energy.

High-performance heterometallic photocatalysts afforded by polyoxometalate synthons for efficient H2 production

MoS2-based materials have emerged as photoelectric semiconductors characterized by a narrow band gap, high capacity for absorbing visible light, and reduced H2 adsorption energy comparable to Pt. These attributes render them appealing for application in photocatalytic hydrogen production. Despite these advantages, the widespread adoption of MoS2-based materials remains hindered by challenges associated with limited exposure to active sites and suboptimal catalytic hydrogen production efficiency. To address these issues, we have designed and synthesized a new class of highly dispersed bimetallic/trimetallic sulfide materials. This was achieved by developing polyoxometalate synthons containing Ni-Mo elements, which were subsequently reacted with thiourea and CdS. The resulting Ni3S2-MoS2 and Ni3S2-MoS2-CdS materials achieve photocatalytic hydrogen production rates of 2770 and 2873 μmol g–1h−1, respectively. Notably, the rate of 2873 μmol g–1h−1 for Ni3S2-MoS2-CdS surpassed triple (3.23 times) the performance of CdS and nearly sextuple (5.77 times) that of single MoS2. These materials outperformed the majority of MoS2-based photocatalysts. Overall, this study introduces a straightforward methodology for synthesizing bimetallic/trimetallic sulfides with enhanced photocatalytic H2 evolution performance. Our findings underscore the potential of transition metal sulfide semiconductors in the realm of photocatalysis and pave the way for the development of more sustainable energy production systems.

Cobalt catalysts for COx-free hydrogen production: Effect of catalyst type on ammonia decomposition in gliding discharge plasma reactor

Hydrogen is considered the cleanest, most environmentally friendly fuel and energy carrier required for the gradual decarbonisation of many industrial sectors. Using ammonia as a Cox-free source of hydrogen is the most reasonable and most applicable method. This paper studies the properties and activity of cobalt catalysts in the ammonia decomposition reaction using a plasma-catalytic system. The effect of catalyst type (supported versus bulk) was evaluated. The catalysts were examined using XRD, STEM-EDX, and sorption techniques (N2 physisorption, TGA-TPR, H2-TPD, CO2-TPD) to reveal the influence of physicochemical properties of these two types of catalysts on the efficiency of NH3 decomposition in the plasma-catalytic process using a gliding discharge plasma. The results disclose that the supported-type catalyst (Ba-Co/CeO2) decomposed NH3 more effectively than the bulk-type catalyst (Co/Ce/Ba). At discharge power of 300 W and flow rate of 180 dm3 h–1 of NH3:N2 mixture (50/50 vol%), the ammonia conversion over the Ba-Co/CeO2 catalyst was 70%, whereas over the Co/Ce/Ba catalyst it was only 21%. The favourable performance of the supported-type catalyst was attributed to a more thermally stable surface area compared with the bulk-type catalyst. Smaller and more stable cobalt nanoparticles (NPs) with numerous weak hydrogen adsorption sites were also seen. Meanwhile, the strong basic sites were generated, improving the electron-donating ability of the surface active sites. High ammonia conversion and relatively low-energy consumption of the plasma-catalytic ammonia decomposition over Ba-Co/CeO2 make it suitable for practical hydrogen production applications, such as fuel cells and hydrogen storage.

Predicting the Structure of Enzymes with Metal Cofactors: The Example of [FeFe] Hydrogenases.

The advent of deep learning algorithms for protein folding opened a new era in the ability of predicting and optimizing the function of proteins once the sequence is known. The task is more intricate when cofactors like metal ions or small ligands are essential to functioning. In this case, the combined use of traditional simulation methods based on interatomic force fields and deep learning predictions is mandatory. We use the example of [FeFe] hydrogenases, enzymes of unicellular algae promising for biotechnology applications to illustrate this situation. [FeFe] hydrogenase is an iron-sulfur protein that catalyzes the chemical reduction of protons dissolved in liquid water into molecular hydrogen as a gas. Hydrogen production efficiency and cell sensitivity to dioxygen are important parameters to optimize the industrial applications of biological hydrogen production. Both parameters are related to the organization of iron-sulfur clusters within protein domains. In this work, we propose possible three-dimensional structures of Chlorella vulgaris 211/11P [FeFe] hydrogenase, the sequence of which was extracted from the recently published genome of the given strain. Initial structural models are built using: (i) the deep learning algorithm AlphaFold; (ii) the homology modeling server SwissModel; (iii) a manual construction based on the best known bacterial crystal structure. Missing iron-sulfur clusters are included and microsecond-long molecular dynamics of initial structures embedded into the water solution environment were performed. Multiple-walkers metadynamics was also used to enhance the sampling of structures encompassing both functional and non-functional organizations of iron-sulfur clusters. The resulting structural model provided by deep learning is consistent with functional [FeFe] hydrogenase characterized by peculiar interactions between cofactors and the protein matrix.

Energy-Saving Electrochemical Hydrogen Production Coupled with Biomass-Derived Isobutanol Upgrading.

The widespread application of electrochemical hydrogen production faces significant challenges, primarily attributed to the high overpotential of the oxygen evolution reaction (OER) in conventional water electrolysis. To address this issue, an effective strategy involves substituting OER with the value-added oxidation of biomass feedstock, reducing the energy requirements for electrochemical hydrogen production while simultaneously upgrading the biomass. Herein, we introduce an electrocatalytic approach for the value-added oxidation of isobutanol, a high energy density bio-fuel, coupled with hydrogen production. This approach offers a sustainable route to produce the valuable fine chemical isobutyric acid under mild condition. The electrodeposited Ni(OH)2 electrocatalyst exhibits exceptional electrocatalytic activity and durability for the electro-oxidation of isobutanol, achieving an impressive faradaic efficiency of up to 92.4 % for isobutyric acid at 1.45 V vs. RHE. Mechanistic insights reveal that side reactions predominantly stem from the oxidative C-C cleavage of isobutyraldehyde intermediate, forming by-products including formic acid and acetone. Furthermore, we demonstrate the electro-oxidation of isobutanol coupled with hydrogen production in a two-electrode undivided cell, notably reducing the electrolysis voltage by approximately 180 mV at 40 mA cm-2 . Overall, this work represents a significant step towards improving the cost-effectiveness of hydrogen production and advancing the conversion of bio-fuels.

Application of ceria materials modified by oxygen vacancies: In photocatalytic process

Cerium-based materials are widely used in various applications such as photocatalytic environmental remediation, CO2 photoreduction and photocatalytic hydrogen production due to their unique optical properties and special oxygen vacancy formation mechanisms. The special external electronic structure of cerium (4f15d16s2f15d16s2), the highly electronic 4f orbital, promotes the formation of oxygen vacancies through Ce4+/Ce3+ conversion, thereby improving the optical properties of the catalyst. Consequently, the application of cerium-based materials in the field of photocatalysis has been of great interest to researchers. In this paper, we briefly review the synthesis of cerium-based photocatalysts and their applications in pollutant removal, CO2 reduction, and hydrogen production, as well as their promising applications.

An Updated Review of Recent Applications and Perspectives of Hydrogen Production from Biomass by Fermentation: A Comprehensive Analysis

Fermentation is an oxygen-free biological process that produces hydrogen, a clean, renewable energy source with the potential to power a low-carbon economy. Bibliometric analysis is crucial in academic research to evaluate scientific production, identify trends and contributors, and map the development of a field, providing valuable information to guide researchers and promote scientific innovation. This review provides an advanced bibliometric analysis and a future perspective on fermentation for hydrogen production. By searching WoS, we evaluated and refined 62,087 articles to 4493 articles. This allowed us to identify the most important journals, countries, institutions, and authors in the field. In addition, the ten most cited articles and the dominant research areas were identified. A keyword analysis revealed five research clusters that illustrate where research is progressing. The outlook indicates that a deeper understanding of microbiology and support from energy policy will drive the development of hydrogen from fermentation.

Advancing Catalysts by Stacking Fault Defects for Enhanced Hydrogen Production: A Review.

Green hydrogen, derived from water splitting powered by renewable energy such as solar and wind energy, provides a zero-emission solution crucial for revolutionizing hydrogen production and decarbonizing industries. Catalysts, particularly those utilizing defect engineering involving the strategical introduction of atomic-level imperfections, play a vital role in reducing energy requirements and enabling a more sustainable transition toward a hydrogen-based economy. Stacking fault (SF) defects play an important role in enhancing the electrocatalytic processes by reshaping surface reactivity, increasing active sites, improving reactants/product diffusion, and regulating electronic structure due to their dense generation ability and profound impact on catalyst properties. This review explores SF in metal-based materials, covering synthetic methods for the intentional introduction of SF and their applications in hydrogen production, including oxygen evolution reaction, photo- and electrocatalytic hydrogen evolution reaction, overall water splitting, and various other electrocatalytic processes such as oxygen reduction reaction, nitrate reduction reaction, and carbon dioxide reduction reaction. Finally, this review addresses the challenges associated with SF-based catalysts, emphasizing the importance of a detailed understanding of the properties of SF-based catalysts to optimize their electrocatalytic performance. It provides a comprehensive overview of their various applications in electrocatalytic processes, providing valuable insights for advancing sustainable energy technologies.

Exploring the impact of thermal oxidation temperature on photoelectrochemical water splitting capabilities of Ga2O3[formula omitted] modified TiO2

This paper reports the influence of thermal oxidation of Ga2O3 thin films deposited on titanium foil substrates via RF magnetron sputtering. The samples were characterized and subjected to photoelectrochemical analysis to assess their photocurrent density response. XRD spectra disclose Ti, TiO2), and Ga2O3 crystal phases. EDX analysis indicates that oxidation temperature reduces oxygen vacancies. Kubelka-Munk technique is used to estimate the optical band gap energies of the TiO2/Ga2O3. The band gap energy decreases from 2.39 to 1.99 and 2.14 eV for TG500 and TG600, whereas TG800 and TG700 increase to 2.98 and 3.09 eV. The TG500 disclosed the highest photocurrent density response of 1382 μAcm−1 at 1.2 V vs. Ag/AgCl in 0.5 M NaOH electrolyte, attributed to decreased oxygen vacancies and band gap. With the strong photocurrent response, stability, and repeatability, the samples may be useful in photocatalytic water-splitting applications for green hydrogen production.

Carbon Intensity During Oil and Gas Production Process

This report focuses on reviewing the types of carbon intensity metrics, and the use of such metrics across the oil and gas sector, to monitor progress towards transitioning away from fossil fuel production. Producers are under pressure to respond to challenging conditions resulting from increasing climate policy, tightening markets and a move away by investors. A number of commentators are suggesting that production may have peaked, given these emerging trends, and the post Covid-19 pandemic. From a combination of review and modeling, this report provides some key insights on carbon intensity metrics and the impact of different carbon intensities on future production, which are pertinent to the future strategies of the oil and gas sector – Narrow-scoped metrics that only include upstream emissions are insufficient for producers reporting on progress towards climate goals. The carbon intensity of the final product also needs to be considered, given that it is increasingly subject to increased demand-side policy e.g. in relation to carbon pricing, bans on the sale of internal combustion engines (ICEs) etc. Given that climate targets are expressed in absolute terms, the relative measure of progress provided by carbon intensity metrics is insufficient to guide progress towards net-zero emissions. As shown by the modelling, there is a significant decline in the levels of production permitted under climate targets by 2050. Given the need for diversification, metrics that account for scope 3 emissions will be important, to help monitor the transformation away from oil and gas. As discussed in this report, a number of IOCs appear to be making small steps in this direction, although their key business focus very much remains on oil & gas. As the IEA (2020a) has reported, less than 1% of capital expenditure is being spent outside of core business areas. However, cleaner operations are also important. Therefore, scope 1&2 metrics are still useful for minimising upstream emissions. The modelling highlights the impact for example of high carbon intensity gas resources (due to methane emissions) on their production levels. Unconventional resources, which tend to require more energy input per unit of extraction, and are more costly, appear unlikely to be exploited in our Paris-aligned case. Any assertion that higher carbon intensity production upstream can be offset by lower emissions downstream (e.g. via higher vehicle efficiency standards) is not supported by the modelling. This is particularly the case where these oil products areexported abroad to regions with low efficiency forms of transportation/limited environmental regulation. National oil companies (NOCs) have more potential to achieve emission reduction from operational emissions, although the incentives to do so might be lower (with far less scrutiny and reporting). Diversification is also likely to be more of a challenge for NOCs, due to the reliance of public budgets on revenues gained. However, a number of high-producing countries are vigorously exploring diversification strategies. Such strategies could include massively increasing support for renewable industries, and focusing on areas such as hydrogen production and CCS applications. For the large NOC producers, with the lowest-cost conventional reserves, it is likely that they may be able to continue producing for the longest time, as climate policy stringency increases. However, given that NOCs hold the largest reserves, risks of stranding will be greater in absolute terms.

Simulation of a sorption-enhanced water gas-shift pilot technology for pure hydrogen production from a waste gasification plant

This study has analysed and optimised a 5-column sorption enhanced water gas shift (SEWGS) pilot unit, set to operate for the first time in a waste gasification facility for the production of transport-grade hydrogen and CO2 streams. Full process simulation was undertaken by developing a one-dimensional model of each reactor, with boundary conditions directly informed by real plant operation. From the sensitivity analysis performed, syngas flowrate variations were seen to have a minor but temporary, impact on hydrogen product specifications, while changes to syngas composition were shown to have a longer-lasting effect on system performance. Based on full cycle operation results, the current 5-column SEWGS unit design was concluded to be inadequate for fuel-cell-grade H2 production, despite obtaining a high H2 purity of 99.5%, mainly due to its excessive steam consumption. However, the process achieved an exceptionally high CO2 purity of 99.9%, and 88.6% hydrogen recovery rate, suggesting its potential use in carbon capture and heat-grade hydrogen production applications.