Clean Hydrogen Production Research Articles

Assessment of a coupled electricity and hydrogen sector in the Texas energy system in 2050

Due to its ability to reduce emissions in the hard-to-abate sectors, hydrogen is expected to play a significant role in future energy systems. This study modifies a sector-coupled dynamic modeling framework for electricity and hydrogen by including policy constraints, carbon prices, and possible hydrogen pathways and applies it to Texas in 2050. The impact of financial policies, including the US clean hydrogen production tax credit, on required infrastructure and costs are explored. Due to low natural gas prices, financial levers are necessary to promote low-carbon hydrogen production as the optimized solution. The Levelized Costs of Hydrogen are found to be $1.50/kg in the base case (primarily via steam methane reformation production) and lie between $2.10 - 3.10/kg when production is via renewable electrolysis. The supporting infrastructure required to supply those volumes of renewable hydrogen is immense. The hydrogen tax credit was found to be enough to drive production via electrolysis.

Governing chemical reactions and mechanisms of hydrogen generation during in-situ combustion gasification of heavy oil

The global push for sustainable energy solutions has highlighted the importance of producing carbon-zero hydrogen (H2) directly from petroleum reservoirs. In-situ combustion gasification (ISCG) presents a groundbreaking method to harness the potential of heavy oil reserves for clean hydrogen production. Although simulations have demonstrated the considerable promise of ISCG, the key reactions controlling hydrogen generation require experimental validation, and the underlying mechanisms remain largely unexplored. This research aims to describe the chemical reactions and mechanisms responsible for hydrogen generation during the ISCG of heavy oil. Using a specially designed kinetic cell, we conducted combustion and gasification experiments with heavy oil and coke. The findings revealed that clay minerals in the reservoir sand act as catalysts in the oxidation reactions of heavy oil by shifting reactions to lower temperatures by approximately 20 °C. Hydrogen production began at 450 °C and peaked at 900 °C, with coke gasification and the water-gas shift reaction being the primary mechanisms. Additionally, methane was produced due to hydrogen consumption via methanation reactions, and minerals in the reservoir sands were found to inhibit hydrogen production by increasing hydrogen consumption and methane generation at temperatures above 800 °C. Controlling the reservoir temperature within an optimal range between 450 and 800 °C can enhance hydrogen generation by managing the process mechanisms. This study provides a detailed examination of the ISCG process for heavy oil, paving the way for future development of kinetic models to simulate hydrogen production through ISCG. It also emphasizes the significance of mechanistic control in enhancing hydrogen generation and suppressing hydrogen consumption reactions.

Sequential oxygen evolution and decoupled water splitting via electrochemical redox reaction of nickel hydroxides

Alkaline water electrolysis is a promising low-cost strategy for clean and sustainable hydrogen production but is largely limited by the sluggish anodic oxygen evolution reaction and the challenges in maintaining adequate separation between H2 and O2. Here, we reveal an anodic-cathodic sequential oxygen evolution process via electrochemical oxidation and subsequent reduction of Ni hydroxides, enabling much lower overpotentials than conventional anodic oxygen evolution. By using (isotope-labeled) differential electrochemical mass spectrometry and in situ Raman spectroscopy combined with density functional theory calculations, we evidence that the sequential oxygen evolution originates from the electrochemical oxidation of Ni hydroxides to NiOO– active species while undergoing a different, reductive step of NiOO– for the final release of O2 due to weakened Ni–O covalency. Based on this sequential process, we propose and demonstrate a hybrid water electrolysis and energy storage device, which enables time-decoupled hydrogen and oxygen evolution and electrochemical energy storage in the Ni hydroxides.

Sustainable fluoride removal with scrap aluminum: Co-producing cryolite and hydrogen

This study presents a novel continuous process for fluoride removal and re- source recovery as cryolite, using a scrap aluminum-packed column. Efficient aluminum dissolution in hydrofluoric acid (HF) generates hydrogen gas and provides cost-saving alkalinity. The process achieves high efficiency (Al/F molar ratio of 2/6) within short Empty Bed Contact Times (15 min) and at low HF concentrations (500 mg/L). Solution pH plays a crucial role, with Al/F ratios above 1 achievable at pH below 4. The exothermic reaction requires temperature control, with a strong correlation (R²=0.99) between HF concentration and heat generation. Hydrogen production matches theoretical predictions. Cryolite synthesis was confirmed at optimized pH (5–5.5) with a 1:1 bypass ratio, achieving 98 % fluoride removal. XRD and SEM- EDS analyses verified cryolite formation. This approach offers a promising solution for industrial fluoride management, resource recovery, and clean hydrogen production.

Optimization of aluminum hydroxide catalyst for efficient hydrogen generation from aluminum-water reaction

The aluminum-water reaction offers a promising method for clean hydrogen production, but it requires an effective catalyst. This study investigates the use of aluminum hydroxide (Al(OH)3) as a catalyst for the aluminum-water reaction to generate hydrogen gas. Various aluminum hydroxide catalysts were synthesized and evaluated for their catalytic performance. The effects of catalyst source, synthesis conditions, quantity, and pH value of the reacting solution were systematically studied. The results demonstrate that self-synthesized, nano-sized Al(OH)3 catalysts exhibit superior catalytic activity compared to commercial sources. Additionally, optimizing the pH value was found to significantly impact the hydrogen generation rate. Proper synthesized Al(OH)3 is capable of completing hydrogen generation within 160 s at pH 11.6, while slightly higher pH value accelerates this reaction down to 60 s. Comparative studies with uncatalyzed reactions at higher pH levels (up to 14) showed significantly slower and incomplete hydrogen production. This research provides insights into developing efficient and sustainable catalytic systems for aluminum-water based hydrogen production.

Environmental life-cycle analysis of hydrogen technology pathways in the United States

Hydrogen is a zero-carbon energy carrier with potential to decarbonize industrial and transportation sectors, but its life-cycle greenhouse gas (GHG) emissions depend on its energy supply chain and carbon management measures (e.g., carbon capture and storage). Global support for clean hydrogen production and use has recently intensified. In the United States, Congress passed several laws that incentivize the production and use of renewable and low-carbon hydrogen, such as the Bipartisan Infrastructure Law (BIL) in 2021 and the Inflation Reduction Act (IRA) in 2022, which provides tax credits of up to $3/kg depending on the carbon intensity of the produced hydrogen. A comprehensive life-cycle accounting of GHG emissions associated with hydrogen production is needed to determine the carbon intensity of hydrogen throughout its value chain. In the United States, Argonne’s R&D GREET® (Greenhouse Gases, Regulated emissions, and Energy use in Technologies) model has been widely used for hydrogen carbon intensity calculations. This paper describes the major hydrogen technology pathways considered in the United States and provides data sources and carbon intensity results for each of the hydrogen production and delivery pathways using consistent system boundaries and most recent technology performance and supply chain data.

Considering Embodied Greenhouse Emissions of Nuclear and Renewable Power Plants for Electrolytic Hydrogen and Its Use for Synthetic Ammonia, Methanol, Fischer-Tropsch Fuel Production.

Recent concerns surrounding climate change and the contribution of fossil fuels to greenhouse gas (GHG) emissions have sparked interest and advancements in renewable energy sources including wind, solar, and hydroelectricity. These energy sources, often referred to as "clean energy", generate no operational onsite GHG emissions. They also offer the potential for clean hydrogen production through water electrolysis, presenting a viable solution to create an environmentally friendly alternative energy carrier with the potential to decarbonize industrial processes reliant on hydrogen. To conduct a full life cycle analysis, it is crucial to account for the embodied emissions associated with renewable and nuclear power generation plants as they can significantly impact the GHG emissions linked to hydrogen production and its derived products. In this work, we conducted a comprehensive analysis of the embodied emissions associated with solar photovoltaic (PV), wind, hydro, and nuclear electricity. We investigated the implications of including plant-embodied emissions in the overall emission estimates of electrolysis hydrogen production and subsequently on the production of synthetic ammonia, methanol, and Fischer-Tropsch (FT) fuels. Results show that average embodied GHG emissions of solar PV, wind, hydro, and nuclear electricity generation in the United States (U.S.) were estimated to be 37, 9.8, 7.2, and 0.3 g CO2 e/kWh, respectively. Life cycle GHG emissions of electrolytic hydrogen produced from solar PV, wind, and hydroelectricity were estimated as 2.1, 0.6, and 0.4 kg of CO2 e/kg of H2, respectively, in contrast to the zero-emissions often used when the embodied emissions in their construction were excluded. Average life cycle emission estimates (CO2 e/kg) of synthetic ammonia, methanol, and FT-fuel from solar PV electricity are increased by 5.5, 16, and 49 times, respectively, compared to the case when embodied emissions are excluded. This change also depends on the local irradiance for solar power, which can result in a further increase of GHG emissions by 35-41% in areas of low irradiance or reduce GHG emissions by 21-25% in areas with higher irradiance.

NiO@GaN nanorods-based core-shell heterostructure for enhanced photoelectrochemical water splitting via efficient charge separation

Remarkable properties of III-V semiconductors, particularly GaN nanostructured based photoelectrodes offers a potential attention in the field of photoelectrochemical water splitting (PEC-WS) for clean and sustainable hydrogen production, due to its wide bandgap, magnificent optoelectrical properties. However, the presence of inevitable surface states in GaN nanorods (NRs) leads to low solar-to-hydrogen (STH) conversion efficiency with poor stability, thereby severely limiting their practical application in PEC-WS, which can be effectively alleviated by constructing a hybrid heterostructures. Herein, we present the development of interfacial engineering of a type-II core-shell heterostructure based on p-NiO nanoparticles (NPs) loaded on n-GaN NRs photoelectrodes for PEC-WS. We assessed the impact of the NiO NPs shell density on core GaN NRs, finding that the optimized NiO@GaN NRs photoelectrode achieved a photocurrent density (Jph) of 1.38 mA/cm² at 1.23 V versus RHE and an excellent applied bias photo-to-current conversion efficiency (ABPE) of ∼0.39 %, which was 3.8 (Jph) and 4.8 (ABPE)-fold times higher than the pristine GaN NRs photoanode under 1-Sun illumination. The type-II p-n heterojunction band alignment between core-shell NiO@GaN NRs photoelectrode effectively reduced the photogenerated carrier recombination rate through surface states passivation and boost the light absorption and harvesting capacity. This facilitates a significant charge separation and transfer at the photoanode/electrolyte interface leading to enhanced redox reactions, resulting in improved PEC-WS and STH performances. These findings offer a promising strategy to design and fabricate highly efficient III-V hybrid heterostructure photoelectrodes for futuristic PEC-WS-based green energy applications.

Unveiling the bi-functional electrocatalytic properties of rhenium di-sulfide nanostructures towards the development of high-rate alkaline water electrolyzer

Alkaline water electrolyzer (AWE) offers a unique solution for generating hydrogen (H2) gas via an electrochemical water-splitting process. The major drawback of the AWE is its limitations in driving high-current densities, an important criterion for the industry standard. In this work, we have demonstrated the bi-functional electrocatalytic properties of ReS2 nanosheets towards hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) with low overpotential (139.2 and 258.89 mV for HER and OER) and Tafel slopes, respectively. The micro/nano electrocatalytic activity of the ReS2 electrocatalyst was examined using a scanning electrochemical microscope (SECM) and Kelvin probe force microscope (KPFM). A lab-scale AWE fabricated using prototype ReS2 electrocatalyst demonstrated that they could drive the benchmark current density (10 mA cm−2) with a low cell voltage of 1.645 V. Further, we also demonstrated a self-powered system comprising an on-shore wind-energy driven ReS2 AWE for sustainable H2 production. Further, the experimental results based on industrially recommended conditions for AWE illustrated that they need only 1.85 V to drive a current density of 500 mA cm−2; thus, ensuring their candidature towards high-rate AWE for clean hydrogen production.

A New Integrated System for Carbon Capture and Clean Hydrogen Production for Sustainable Societal Utilization

Hydrogen production and carbon dioxide removal are considered two of the critical pieces to achieve ultimate sustainability target. This study proposes and investigates a new variation of potassium hydroxide thermochemical cycle in order to combine hydrogen production and carbon dioxide removal, synergistically. An alkali metal redox thermochemical cycle developed where the potassium hydroxide is considered by using a nonequilibrium reaction. Also, the multigeneration options are explored by using two stage steam Rankine cycle, multi-effect distillation desalination, Li-Br absorption chiller, which are integrated with potassium hydroxide thermochemical cycle for hydrogen production, carbon capture, power generation, water desalination, and cooling purposes. A comparative assessment under different scenarios is carried out. The energy and exergy efficiencies of the hydrogen production thermochemical cycle are 44.2% and 67.66% when the hydrogen generation reaction is carried out at 180°C and the separation reactor temperature set at 400°C. Among the multigeneration scenarios, a trigeneration option of hydrogen, power and water indicates the highest energy efficiency as 66.02%. For

A new system using refuse-derived fuel as a feedstock for hydrogen and power co-generation: A techno-environmental assessment

Refuse-derived fuel (RDF) offers a promising opportunity for Canada to proceed with its transition towards a circular economy. This study focuses on the development of a pseudo-steady-state process simulation model to integrate RDF processing and utilization technologies with the existing plants. Canada’s RDF is chosen as a potential feedstock and is coupled with the two cycles, namely Sulfure Iodine (S-I) thermochemical cycle for hydrogen production and dual pressure loop power (DPLP) cycle for electricity generation. A comprehensive process modeling and simulation is undertaken in the Aspen Plus software package. An integrated environmental and thermodynamic assessment of the plant, including energy and exergy analyses, is conducted. Several sensitivity analyses are conducted to predict the ideal operational parameters for optimized efficiency. It is found that a feed of 1300 kg/h RDF generates 96.76 kg of clean hydrogen and 382.24 kW of clean power. The results show RDF-to-power and RDF-to-H2 energy efficiency of 22.19 % and 25.27 % respectively. Regarding the environmental performance, the results show that the proposed plant avoids 423.82 tons of CO2 emissions per year for clean hydrogen production and 1685.45 tons of CO2 emissions per year for clean power production. The overall performance of the developed system in terms of efficiencies is 35.91 % for energy and 42.46 % for exergy.

Development of a novel renewable energy-based integrated system coupling biomass and H2S sources for clean hydrogen production

The present work aims to develop a novel integrated energy system to produce clean hydrogen, power, and biochar. The Palmaria palmata, a type of seaweed, and hydrogen sulfide from the industrial gaseous waste streams are taken as potential feedstock. A combined thermochemical approach is employed for the processing of both feedstocks. For clean hydrogen production, the zinc sulfide thermochemical cycle is employed. Both stoichiometric and non-stoichiometric equilibrium-based models of the proposed plant design are developed in the Aspen Plus software, and a comprehensive thermodynamic analysis of the system is also performed by evaluating energy and exergy efficiencies. The study further explores the modeling, simulation, and parametric analyses of various subsections to enhance the hydrogen and biochar production rate. The parametric analyses show that the first step of the thermochemical cycle (sulfurization reaction) follows stoichiometric pathway and the ZnO to H2S ratio of 1 represents the optimal point for reactant conversion. On the other hand, the second step of the thermochemical cycle (regeneration reaction) does not follow a stoichiometric pathway and ZnS conversion of 12.87% is achieved at a high temperature of 1400oC. It is found that a hydrogen production rate of 0.71 mol/s is achieved with the introduction of 0.27 mol/s of H2S. The energy and exergy efficiencies of the zinc sulfide thermochemical cycle are found to be 65.23% and 35.58% respectively. A biochar production rate of 0.024 kg/s is obtained with the Palmaria palmata fed rate of 0.097 kg/s. The Palmaria to biochar energy and exergy efficiencies are found to be 55.43% and 45.91% respectively. The overall energy and exergy efficiencies of the proposed plant are determined to be 72.88% and 50.03% respectively.

Ultrathin B:NiCoOx-modified BiVO4 photoanode with abundant oxygen vacancies for photoelectrochemical glycerol conversion coupled with hydrogen production

Photoelectrochemical (PEC) conversion of glycerol (GLY) into high value-added chemicals coupled with clean hydrogen production can be achieved over a BiVO4-based PEC cell, but the low photocurrent density and poor photostability of the most BiVO4 photoanodes limit the PEC performance and sustainable application of solar resources. Herein, we construct a high-efficiency stable photoanode by decorating an amorphous ultrathin B-activation NiCoOx (B:NiCoOx) nanolayer with abundant oxygen vacancies (Ov) on the BiVO4 photoanode via a simple immersing process. We demonstrate the optimized B:NiCoOx/BiVO4 photoanode in the PEC GLY oxidation yields a high photocurrent density of 6.05 mA cm−2 at 1.23 VRHE, a formic acid (FA) production rate of 360.3 mmol m−2 h−1, a dihydroxyacetone (DHA) production rate of 228.4 mmol m−2 h−1, with simultaneously hydrogen production at the cathode. An intermittent 60-h PEC GLY oxidation assay results indicates the superb durability of the B:NiCoOx/BiVO4 photoanode. The outstanding PEC performance is predominantly ascribed to the amorphous ultrathin structure of the B:NiCoOx nanolayer (∼ 2 nm) and the abundant Ov, which effectually accelerates the photogenerated holes transport/extraction and offers more catalytic active sites for the PEC GLY oxidation. Moreover, the free state and adsorbed state •OH radicals originated from active oxygen are deduced to be responsible for the oxidation of GLY to FA and GLY to DHA. This study develops a sustainable BiVO4-based catalyst with high activity and photostability for the PEC GLY oxidation and hydrogen production.

Heterophase homojunction construction by amorphous TiOx and N–TiO2 photoanode for oxygen evolution reaction kinetics and charge carriers’ transportation enhancement

Photoelectrochemical (PEC) water splitting by TiO2 photoanode for clean hydrogen production is limited by the poor charge separation and inert oxygen evolution reaction (OER) kinetics issues for now. In this work, a band-matched heterophase homojunction (TiOx/N–TiO2) by amorphous TiOx and N-doped TiO2 nanotube arrays is constructed by two-step anodic oxidation and impregnation. The photocurrent density of TiOx/N–TiO2 reaches 0.69 mA/cm2 at 1.23 V vs. RHE, which is 1.86 folds than bare TiO2. The enhanced charge carriers' injection/separation efficiency, smaller Tafel slope (37.79 mF dec−1) and larger electrochemical active surface area (ECSA) (1.98 mF cm−2) of TiOx/N–TiO2 indicate that N doping and heterophase homojunction with amorphous TiOx effectively facilitate the surface OER kinetics and charge carriers' transportation. TiOx/N–TiO2 is annealed with a transformation of the surface amorphous TiOx layer into anatase TiO2 (a-TiOx/N–TiO2) to study the role of amorphous TiO2 in PEC water splitting. The photocurrent density and applied bias photon-to-current efficiency (ABPE) for a-TiOx/N–TiO2 decrease, even lower than the pristine TiO2. This is due to the reduction of surface oxygen vacancies, which causes the slowdown of OER kinetics and the weakening of charge carrier transportation ability. That is favorable for a better understanding of the OER kinetics and charge carriers’ transportation enhancement mechanism by the surficial modification on the semiconductor during the PEC water splitting.

Composite Anode for PEM Water Electrolyzers: Lowering Iridium Loadings and Reducing Material Costs with a Conductive Additive.

To enable the greater installed capacity of proton exchange membrane water electrolysis (PEMWE) for clean hydrogen production, associated costs must be lowered while achieving high current density performance and durability. Scarce and expensive iridium (Ir) required for the oxygen evolution reaction (OER) is a large contributor to the overall cost, yet high loadings of Ir (1-2 mgIr cm-2) are currently needed in commercial systems to maintain sufficient activity, conductivity, and durability. To meet the aggressive targets for low Ir loadings, we introduce a composite anode approach using a conductive additive that is less expensive than Ir to facilitate robust, high-performance operation with low Ir loading by retaining electrode thickness and in-plane electrical conductivity. In this demonstration, we use platinum (Pt) black as the conductive additive given its high electrical conductivity, acid stability, and current price one-fifth that of Ir. Using a high-activity commercial Ir oxide (IrO x ) catalyst, we present a 95% Ir loading reduction and 80% cost reduction of the anode catalyst materials while maintaining equal current density performance at a cell voltage of 1.8 V. Furthermore, we show enhanced stability of a composite anode compared to an IrO x anode with loadings of 0.10 mgIr cm-2 via accelerated stress test (AST) and postmortem imaging. With this approach, we show promising results toward lowering Ir loadings and material costs, addressing a significant barrier to the widespread adoption of PEMWE for clean hydrogen production.

Catalytic and non-catalytic reactions of methane pyrolysis for hydrogen production in screening and electromagnetic levitation reactors using computational fluid dynamics

Molten metal (MM)-based methane (CH4) pyrolysis is a promising technology for clean hydrogen production with a minimal carbon footprint. Electromagnetic levitation (EMLR) and screening reactors (SR) were used to investigate the intrinsic catalytic reaction kinetics of MM-based CH4 pyrolysis. Heterogeneous catalytic reactions in the SR and EMLR occurred on the surfaces of the MM crucible and droplet, respectively. However, a homogenous non-catalytic reaction may occur just above the surface because the CH4 gas is preheated by the high-temperature MM. This study presents three-dimensional (3D) computational fluid dynamics (CFD) model coupled with chemical reactions to assess the extent to which non-catalytic reactions intervene in CH4 pyrolysis in both the SR and EMLR, which is difficult to measure experimentally. The CFD model validated against experimental data revealed that the non-catalytic reaction accounted for 4.0 % of CH4 pyrolysis in the CH4-Ni0.27Bi0.73 SR at 1045 °C, whereas it represented 0.02 % in the CH4-Sn EMLR at 1021 °C. This result highlights that the EMLR is suitable for studying the intrinsic catalytic reaction kinetics of MM-based CH4 pyrolysis because the non-catalytic reaction occurs to a lesser extent.

A novel cryogenic-thermochemical approach for clean hydrogen production from industrial flue gas streams with carbon capture and storage

The present work aims to develop a novel integrated energy system for clean hydrogen production from the industrial flue gas stream. The particular system incorporates a cryogenic distillation unit for H2S and CO2 separation and a thermochemical cycle for hydrogen production. The industrial flue gaseous mixture is considered a major feedstock for the present system. H2S is retrieved from the waste gaseous stream and fed to the two-step sulfur looping thermochemical cycle to perform clean hydrogen production. In this way, clean hydrogen production, elemental sulfur production, carbon capture, and storage are achieved. The entire integrated energy system is simulated in the Aspen Plus process simulator and is investigated thermodynamically in terms of energy and exergy performances. Various parametric studies are conducted to assess the significance of operating parameters on the system performance. The H2S and CO2 removal rates from the waste feed stream are found to be 85.55 % and 84.62 %. The H2S conversion into hydrogen is determined to be 66.67 %. The energy and exergy efficiencies of the two-step thermochemical cycle are found to be 53.93 % and 23.69 %, respectively. The parametric studies show that the hydrogen production rates of 3.63 kmol/h, 2.46 kmol/h, and 1.78 kmol/h are achieved at sulfurization temperatures of 200 °C, 300 °C, and 500 °C, respectively. The study further concludes that 44.60 % of the total input exergy is lost due to the presence of irreversibilities within the system. The overall energy and exergy efficiencies of the integrated energy system are found to be 82.99 % and 55.39 %, respectively.

Copper/ cerium metal organic frame work as highly efficient structures for solar power-induced hydrogen generation through the process of water splitting

Increased dependence on fossil fuels as energy sources strongly contributes in both global warming and environmental pollution, leading to serious impacts on human-beings and societies. Therefore, shift from hydrocarbon-based energy to alternative green, sustainable and renewable sources of energy has been globally stimulated in past decades. In an agreement with this context, hydrogen is counted as one of these sources which has been paid strong attention recently due to its high energy content and no harmful emissions. Consequently, this study introduces production of clean green hydrogen through the process of photocatalytic water splitting which is a cost-effective route and releases zero emissions. A series of copper/ or cerium based metal–organic frameworks were successfully prepared via one-pot solvothermal technique and were presented as three novel photocatalysts for hydrogen production from water. The photocatalytic performances of these structures were investigated under visible light irradiation, revealing the highest activity for copper doped cerium metal–organic framework. It exhibited a maximum pure hydrogen productivity of 465 mmol per hour/ gram which was much higher than those the detected productivity by copper and cerium metal–organic frameworks (289 and 375 mmol per hour/ gram respectively). Heterojunction between the two central metals as well as effective charge separation in copper doped cerium metal–organic framework are reasons of its superiority in hydrogen evolution exploit, compared to the other two structures. The recyclability of copper doped cerium metal–organic framework demonstrated high reliability since it showed nearly stable yields of hydrogen over ten cycles of photocatalytic reuse. Therefore, the presented binary metals organic framework establishes new platform for photocatalysts in process of hydrogen production through water splitting.

High-efficiency photocatalytic H2-evolution in water/seawater over a novel noble metal free Ni3C/Mn0.5Cd0.5S Schottky junction

Solar-powered seawater production of clean hydrogen fuel is highly prospective. In this work, Ni3C/Mn0.5Cd0.5S (NCMCS) Schottky junctions with excellent visible-light correspondence and photogenerated carrier separation properties are constructed using electrostatic attraction. The material achieves a hydrogen evolution rate of 6472.9 μmol h−1 g−1 in simulated seawater, which is 11 times higher than that of a single Mn0.5Cd0.5S (MCS). More attractively, the composite exhibits excellent hydrogen evolution rates in natural river water, groundwater and tap water, with significantly enhanced practical applicability. The underlying hydrogen evolution mechanism was extrapolated from a combination of experimental and theoretical calculations. The present work provides a low-cost and efficient hydrogen evolution photocatalyst for practical application, which can help promote the efficient conversion of solar-hydrogen energy.

A Reduced-Order Model of a Nuclear Power Plant with Thermal Power Dispatch

This paper presents reduced-order modeling of thermal power dispatch (TPD) from a pressurized water reactor (PWR) for providing heat to nearby heat consuming industrial processes that seek to take advantage of nuclear heat to reduce carbon emissions. The reactor model includes the neutronics of the reactor core, thermal–hydraulics of the primary coolant cycle, and a three-lump model of the steam generator (SG). The secondary coolant cycle is represented with quasi-steady state mass and energy balance equations. The secondary cycle consists of a steam extraction system, high-pressure and low-pressure turbines, moisture separator and reheater, high-pressure and low-pressure feedwater heaters, deaerator, feedwater and condensate pumps, and a condenser. The steam produced by the SG is distributed between the turbines and the extraction steam line (XSL) that delivers steam to nearby industrial processes, such as production of clean hydrogen. The reduced-order simulator is verified by comparing predictions with results from separate validated steady-state and transient full-scope PWR simulators for TPD levels between 0% and 70% of the rated reactor power. All simulators indicate that the flow rate of steam in the main steam line and turbine systems decrease with increasing TPD, which causes a reduction in PWR electric power generation. The results are analyzed to assess the impact of TPD on system efficiency and feedwater flow control. Due to the simplicity of the proposed reduced-order model, it can be scaled to represent a PWR of any size with a few parametric changes. In the future, the proposed reduced-order model will be integrated into a power system model in a digital real-time simulator (DRTS) and physical hardware-in-the-loop simulations.