Hydrogen Production Process Research Articles

Ammonia autothermal reformer with air side-stream distribution for hydrogen production

Recently, there has been growing interest in utilizing ammonia through its decomposition process for on-site hydrogen production, primarily due to technical problems in hydrogen generation and storage. As ammonia decomposition is an endothermic reaction, an external heat source is required to facilitate the reaction. To address this, an ammonia autothermal reforming process that directly integrates ammonia decomposition and oxidation using air as the source of oxygen within a single reactor vessel was proposed. This process eliminates the need for additional external heat sources and simplifies the process. The design of the reactor incorporates an air distribution structure that allows for achieving a specified temperature range for the desired reaction. Thermodynamic analysis of the autothermal system revealed that high feed temperature, high reaction temperature, and low pressure are the most beneficial conditions for generating a high yield of hydrogen. The proposed process was simulated to assess its feasibility using kinetic parameters obtained from experimental data in the literature [27]. An optimization problem to minimize the reactor length in designing the proposed reactor was developed. The reactor design produces a high yield of hydrogen while maintaining the reaction temperature within the desired range. Adjusting the air flow rate at distribution points along the reactor to maintain peak temperatures at predetermined levels was shown to provide good load flexibility for variations in ammonia flow rate.

Life cycle assessment and life cycle cost analysis of surgical mask from production to recycling into hydrogen process

Global greenhouse gas emissions and medical supply management systems are facing increasing challenges at the social, environmental, and economic levels. This study aims to propose a multi-objective assessment method coupled with life cycle assessment and life cycle cost analysis to evaluate the entire process of medical supply represented by surgical mask from production to recycling into hydrogen from environmental and economic perspectives. Mass and energy flow data are obtained from literature and the hydrogen production process by plasma gasification of surgical mask established using Aspen Plus. The results reveals that the life cycle energy consumption, global warming potential, acidification potential and photochem ozone creation potential in the surgical mask collection, pretreatment, plasma gasification and waste heat recovery stage account for 77.34%, 40.20%, 46.00% and 44.63% of the entire life cycle, respectively. Operating costs have a significant impact and using of fully automatic equipment and improving the energy consumption of plasma torches are critical to reducing system operating costs. A sensitivity analysis of the four modes of hydrogen transport is performed, and the best mode of hydrogen transport is proposed. This study provides basic information reference for the medical product management system.

A-site defects boosted exsolution on (La0.5Ca0.5)(1-α)Ni0.06Ti0.94O3-δ for ethanol steam reforming

With global industrialization and population increase, the constraints of fossil fuels in terms of price and environmental protection necessitate the development of alternate energy sources. Ethanol reforming, as a non-fossil-originated hydrogen production process, has become an industrially promising reaction. In this work, perovskite titanate (La0.5Ca0.5)(1-α)Ni0.06Ti0.94O3-δ with different A-site deficiency was synthesized via a modified Pechini method. Orthorhombic titanates with grain size of 200 to 500 nm were obtained with nickel cooperated into the frameworks. The extent of A-site deficiency influences the size and population of exsolved nickel particles. Higher A-site defects would greatly induce the exsolution of nickel, thus promoting the catalytic activity in ethanol steam reforming reaction. La0.4Ca0.4Ni0.06Ti0.94O3-δ sample showed an outlet composition that was closed to thermodynamic equilibrium under S/C = 3 and WHSV = 8.8 gethanol/(gcat·h). The metal agglomeration was inhibited during 8-hour reforming at high temperatures, while the deactivation during the stability test was mainly due to the formation of graphite carbon.

A new approach for evaluating photosynthetic bio-hydrogen production: The dissipation rate method

A dissipative rate model is established by using the non-equilibrium thermodynamics method to evaluate photosynthetic bio-hydrogen production process. The mass transfer dissipation rate, chemical reaction dissipation rate and total dissipation rate for the bio-hydrogen production processes with glucose and acetic acid are calculated and analyzed respectively by using the proposed dissipation rate model. When substrate concentration is taken as variable (15 g/L,20 g/L and25 g/L), the total dissipation rate and mass transfer phenomenological coefficient of hydrogen production process with 20 g/L are the lowest, and the maximum dissipation rate is 7.7288J/h. The phenomenological coefficient of chemical reaction is larger at high concentration. When the temperature is variable (298.15 K,303.15Kand308.15 K), the dissipation rate is lowest at 303.15 K and the chemical reaction coefficient is largest and the maximum dissipation rate is 6.0596J/h. In addition, the mass transfer phenomenological coefficient is larger at high temperature. With the initial pH as variable (6.5,7.0,7.5), the maximum dissipation rate of 11.2271J/h is obtained at pH 7.5. At high pH, the mass transfer phenomenological coefficient is large and the chemical reaction coefficient is exactly the opposite. This model can predict the energy dissipation law in the process of photosynthetic biohydrogen production, and provide a theoretical basis for the subsequent process optimization.

Simulation of the Catalytic Gasification of Banana Biomass in the Production of Hydrogen, Using Glucose as a Model Compound

In the face of the climate change problem caused by fossil fuels, it is essential to seek efficient alternative energies with a lower environmental impact that are derived from renewable resources. Biomass gasification technology continues to generate significant interest in sustainable energy research as an alternative to traditional combustion technology. Gasification involves the thermochemical conversion of raw materials, resulting in a highly valuable gaseous product known as synthesis gas, commonly used as a fuel. Its numerous advantages include the availability of raw materials, the reduction in harmful emission streams, performance, and costs. As this topic gains momentum in the global energy framework, it is imperative to advance the maturity of this technology by addressing its weaknesses, primarily in terms of efficiency. The objective of this project was to investigate the hydrogen production process through the simulation of glucose gasification as a representative compound for biomass. This was achieved by conducting an integrated simulation of glucose gasification, encompassing both the heat transfer in the external system and the conversion of glucose into hydrogen gas, using the results obtained in the external system as initial conditions. Interrelated aspects of this complex process, including heat transfer and the kinetics of the gasification process, were modeled. Glucose was selected as the model compound due to its availability, simplicity, fundamental understanding, reproducibility, comparability, knowledge of reaction pathways, and simplification of mathematical models. The simulation resulted in a H2:CO ratio of 2.2, and molar fluxes were obtained for H2, CO, CO2, CH4, and H2O consistent with those typically observed in the gasification process of organic matter. These models were constructed, laying the foundation for the adaptability of subsequent optimization studies.

Accelerated hydrogen production on atomically thin silicon nanosheets photocatalyst with unique surface adsorption chemistry

Compared with widely explored layered materials, the atomically thin layer based on nonlayered materials and their thickness dependent properties are less reported. Recently, silicon nanosheet as a novel non-layered 2D material is getting burgeoning attentions. Herein, based on density functional theory calculations, we reveal that freestanding atomically thin silicon nanosheets display favorable hydrogen evolution kinetics including small hydrogen adsorption energy and low hydrogen evolution barrier, which is distinct from multilayer silicon nanosheets and bulk silicon surface. This unique surface adsorption chemistry greatly contributes to the photocatalytic hydrogen production process. Atomically thin silicon nanosheets were further prepared by a liquid phase exfoliation approach and its cocatalyst-free photocatalytic hydrogen production performance is evaluated. The results confirmed that the photocatalytic activity of atomically thin silicon nanosheets vigorously outperforms that of bulk silicon and multilayer silicon flakes. The average hydrogen production rates of A-SiNS can reach158.8 μmol h−1 g−1, which is about 3.2 times higher than that of M-SiNS (49.5 μmol h−1 g−1). This work not only supports atomically thin silicon nanosheets as a potential candidate for photocatalytic reactions but also brings new insights into its unique physiochemical properties and applications.

Numerical and experimental investigation of irradiance profiles on suspended particles in a flat disk photoreactor for hydrogen generation

Regarding sustainable energy alternatives, the present work evaluates hydrogen production using suspended particles exposed to an irradiance of 247 W/m2. A 1.0 L flat disk photoreactor (FDP) was designed for evaluating agitation speeds of 100, 175, and 250 RPM, and particle concentrations of 0.5, 1.0, and 2.0 g/L. Through CFD-assisted, a non-conformal meshing of 551,000 polyhedral elements was created, coupling Volume of Fluids, Discrete Particle Modelling, and Discrete Ordinates Model methods. Transient simulation shows a maximum particle homogenization of 84 % at 0.5 g/L and 250 RPM, and a maximum average exposure profile of 140 W/m2 for 27% of the particles with an initial loading of 1.0 g/L at 250 RPM.Effective concentration in the FDP was measured, determining an accuracy of 84.35% and 71.32%, respectively, concerning the model used in the simulation. It is concluded that the FDP developed provides good semiconductor behavior for an effective hydrogen production process.

Proposal and exergetic/net present value optimization of a novel integrated process into a two-stage geothermal flash cycle, involving bi-evaporator refrigeration unit: Application of non-dominated sorting genetic algorithm (NSGA-II+LINMAP) method

Considering the benefits of geothermal energy in low-temperature combined processes, this study intends to present, examine, and optimize a novel thermal integration process incorporated into a two-stage geothermal flash cycle. In order to meet this objective, a modified bi-evaporator refrigeration technology using an ejector has been designed, with the capability of generating coolant for air-conditioning and industrial requirements. Furthermore, the entire system utilizes a low-temperature water electrolysis process for hydrogen production. In addition to designing a new process, this study incorporates advanced methodologies to comprehensively analyze the proposed system's thermodynamic, economic, and exergoenvironmental aspects. In this context, an extensive parametric study is undertaken, followed by the definition of two distinct multi-objective optimization scenarios: the energy-environment and the energy-cost scenarios. Based on the outcomes derived from the first scenario, the corresponding objective functions, namely energy efficiency and exergoenvironmental index, are determined to be 52.89% and 0.5, respectively. This condition is also responsible for generating net output electricity, cooling load, and hydrogen production rate of 3.897 MW, 26.88 MW, and 4.02 kg/h, respectively. Moreover, it exhibits an exergy destruction rate of 5493 kW. In the second scenario, the objective functions, i.e., energetic efficiency and payback period, are calculated to be 39.37% and 3.94 years, respectively. The aforementioned products demonstrate capacities of 3.697 MW, 17.66 MW, and 5.0 kg/h, respectively. Besides, the exergy destruction rate is determined to be 4667 kW.

In-situ formation of SrTiO3/Ti3C2 MXene Schottky heterojunction for efficient photocatalytic hydrogen evolution

Surface and interface engineering of composite photocatalysts are effective ways to enhance the dynamics of photo-generated charge carriers. In this work, SrTiO3/Ti3C2 MXene (STO/TC) Schottky heterojunction is constructed by in-situ growth of SrTiO3 (STO) on Ti3C2 MXene (TC) through Sr(OH)2 etching the surfaces of TC. This in-situ growth strategy not only creates the tight chemically bonded interfaces by SrTiO3 nanoparticles uniformly anchoring on the surface of two-dimensional Ti3C2 MXene nanosheets for promoting the photo-generated charge carrier separation, but also introduces surface Ti vacancies as the efficient catalytic active sites to accelerate the charge carrier transfer process for efficient hydrogen production. The photocatalytic system constructed by interface and surface engineering optimizes the photo-generated charge carrier dynamics and refines the photocatalytic hydrogen evolution performance (6.8 times higher than pristine SrTiO3) and stability. This work is expected to provide an alternative strategy to construct highly efficient photocatalysts with hydrogen evolution.

Understanding Structure-Activity Relationship in Pt-loaded g-C3 N4 for Efficient Solar- Photoreforming of Polyethylene Terephthalate Plastic and Hydrogen Production.

Coupling the hydrogen evolution reaction with plastic waste photoreforming provides a synergistic path for simultaneous production of green hydrogen and recycling of post-consumer products, two major enablers for establishment of a circular economy. Graphitic carbon nitride (g-C3 N4 ) is a promising photocatalyst due to its suitable optoelectronic and physicochemical properties, and inexpensive fabrication. Herein, a mechanistic investigation of the structure-activity relationship of g-C3 N4 for poly(ethylene terephthalate) (PET) photoreforming is reported by carefully controlling its fabrication from a subset of earth-abundant precursors, such as dicyandiamide, melamine, urea, and thiourea. These findings reveal that melamine-derived g-C3 N4 with 3wt.% Pt has significantly higher performance than alternative derivations, achieving a maximum hydrogen evolution rate of 7.33mmolH2 gcat -1 h-1 , and simultaneously photoconverting PET into valuable organic products including formate, glyoxal, and acetate, with excellent stability for over 30h of continuous production. This is attributed to the higher crystallinity and associated chemical resistance of melamine-derived g-C3 N4 , playing a major role in stabilization of its morphology and surface properties. These new insights on the role of precursors and structural properties in dictating the photoactivity of g-C3 N4 set the foundation for the further development of photocatalytic processes for combined green hydrogen production and plastic waste reforming.

Green hydrogen production by water splitting using scrap metals at high temperature

Currently green hydrogen production is attracting global attention. In this context, sustainable hydrogen production processes have been explored by using variety of materials and methods. Generation of hydrogen without CO2 emissions is the key for carbon-free energy economy in future. Enormous amounts of scrap iron, metallurgical wastes and ferrous metals are produced in industrial processes. In this work, the reaction between metal scrap and steam is studied for hydrogen production. The scrap materials are loaded in a packed-bed reactor to produce green hydrogen by water splitting at high temperatures. This method produced 500 mL of green H2 per gram of scrap material at 1150 °C with a conversion efficiency of about 94%. This is a potential method to utilize the scrap metals for large scale production of green hydrogen without carbon emissions.

Development and assessment of an offshore-based integrated hydrogen production and liquefaction system

The conventional hydrogen production methods depending on fossil fuels raise sustainability concerns. Therefore, there is a crucial need to develop sustainable and energetically self-sufficient hydrogen production processes. In this paper, an integrated hydrogen production and liquefaction system is developed to meet the hydrogen energy needs of communities. For this purpose, the present integrated system is considered and applied to the Hornsea Wind Farm, being developed off the east coast of the East Coast in the North Sea. The system aims to produce gaseous hydrogen by an electrolyzer and liquefy it by utilizing the energy input coming from a wind farm. The thermodynamic analysis is performed for the overall system and its components using energy and exergy methods through balance equations. Furthermore, the parametric evaluations are implemented to investigate the effects of varying operational conditions and design parameters on some key energy and exergy performance indicators. Under the specified conditions, the current study obtains the following results: an overall energy efficiency of 70.45 %, an overall exergy efficiency of 57.32 %, and a specific energy consumption of liquefaction plant (SEC) of 62.24 kWh/kg-LH2. Moreover, the levelized cost of H2 for the plant is found to be $7.28/kg. This research also reveals the primary sources of exergy losses by providing valuable insights to enhance the system's exergetic performance with some potential optimization opportunities. Furthermore, this study is expected to help achieve a more sustainable and decarbonized energy future with green hydrogen production and liquefaction for use.

Sustainable biohydrogen production from lignocellulosic biomass sources - metabolic pathways, production enhancement, and challenges.

Hydrogen production from biological processes has been hailed as a promising strategy for generating sustainable energy. Fermentative hydrogen production processes such as dark and photofermentation are considered more sustainable and economical than other biological methods such as biophotolysis. However, these methods have constraints such as low hydrogen yield and conversion efficiency, so practical implementations still need to be made. The present review provides an assessment and feasibility of producing biohydrogen through dark and photofermentation techniques utilizing various lignocellulosic biomass wastes as substrates. Furthermore, this review includes information about the strategies to increase the productivity rate of biohydrogen in an eco-friendly and sustainable manner, like integration of dark and photofermentation techniques, pretreatment of biomass, genetic modification of microorganisms, and application of nanoadditives.

A comparative economic study of nuclear hydrogen production, storage, and transportation

The cost of hydrogen production from environmentally friendly energy resources is a primary barrier to fully realizing a hydrogen economy. Therefore, a detailed analysis of hydrogen production costs from various sustainable routes is required. This paper presents a comparative economic study of hydrogen production using several nuclear reactors integrated with electrolysis hydrogen production methods. The Hydrogen Economic Evaluation Program (HEEP) software is used for comparing hydrogen production using different technologies. The HEEP tool was developed by International Atomic Energy Agency (IAEA) and offers comprehensive data for the different nuclear power plants, hydrogen production processes, and various storage and transportation options. The current study utilizes HEEP capabilities to evaluate the cost of nuclear hydrogen production and compare it with non-nuclear sources. Furthermore, it considers the cost of hydrogen storage and transportation options. The reactors considered are Advanced Pressurized Water Reactor (APWR) and High Temperature Gas-cooled Reactor (HTGR) to power low- and high-temperature electrolyzers. In addition, the costs of hydrogen produced using electricity from grid, solar, and wind are evaluated and compared with that of nuclear plants. It is found that the cost of hydrogen production and storage using Compressed Gas (CG) from an APWR plant is 8.2 $/kg for a plant capacity of 360 MWe; the cost is reduced to 6.06 $/kg when the capacity increased to 1117 MWe. It is also found that HTGR integrated with HTSE can produce hydrogen at 3.51 $/kg, which is slightly lower than the case of using the grid electricity, which costs 3.55 $/kg.

Comparative Analysis of Energy and CO2 Emission for the Integration of Biomass Gasification with a Dual-Reactor Chemical Looping Hydrogen Production Process

Comparative Analysis of Energy and CO₂ Emission for the Integration of Biomass Gasification with a Dual-Reactor Chemical Looping Hydrogen Production Process

Automated IBEX crawler for PAUT inspection for in-service ferromagnetic assets

In order to guarantee the safety of the gas production plants, Air Liquide conducts NDT inspections regularly closely following the assets’ maintenance plans. One high criticality asset is the Pressure Swing Adsorber (PSA), found in the last stages of the hydrogen production process, where product purification takes place. These adsorbers are pressure vessels and need to be inspected for hydrogen enhanced fatigue cracks. Conventional inspection would require stopping site operation, building scaffolding for the totality of the height, which depending on design can be up to 15 meters tall and 6 meters in diameter, grinding of the inspection surface to remove the paint, conducting the inspection manually by 2 operators, and repainting once inspections are concluded. Commonly, inspection plans for these high-criticality assets outline a high inspection frequency, resulting in elevated costs associated with logistics, personnel and time and monetary resources required to plan and execute each inspection. This necessity is what drove Air Liquide R&D and INTACT to create a partnership and develop an automated crawler that can be deployed on in-service ferromagnetic assets for Phased Array Ultrasonic Testing (PAUT) inspection, using Total Focusing Method (TFM) with INTACT proprietary imaging and software. The robot, named IBEX Crawler, is deployed at the lowest part of the vessel and controlled safely at the ground level by a single operator. It is able to change directions to accommodate the inspection of longitudinal and circular welds. It includes an encoding system that enables operators to exactly locate any indications present. The crawler’s payload includes an electronic 128 elements PAUT board controlled by fiber optics, laser tracking and machine vision camera. The inspection results are analyzed by 3D reconstruction and managed by mechanical integrity assessments proprietary technology, calculating the stability of the found indications and using fracture mechanics and Fitness-For-Service (FFS) to estimate the residual lifetime of the indications and in consequence, the interval between inspections to develop a more accurate maintenance plan. Today INTACT’s IBEX crawlers travel worldwide between Air Liquide sites to ensure the integrity of the assets.

Fabrication of micro/nano wettability MoS2 hydrogen evolution electrocatalyst based on femtosecond laser

The process of hydrogen production through water electrolysis involves ionic interactions and the dynamic process of hydrogen bubble formation on the electrode surface. In this study, we employed a combination of femtosecond laser and hydrothermal synthesis to fabricate a novel MoS2 electrode. The double-scale structure of this substrate increases its specific surface area, facilitating the presence of active sites for the hydrogen evolution reaction. The growth of nano-scale catalyst further enhances wettability, promoting rapid detachment of gas bubbles and replenishment of water. This method not only facilitates ionic interactions but also accelerates the formation of macroscopic bubbles. Under alkaline conditions, electrode achieved an impressive current density of 10 mA cm−2 with a low overpotential of only 99 mV. This novel MoS2 hydrogen evolution catalyst holds practical value, paving the way for the design of more efficient and stable electrocatalysts.

Efficient Decoupled Alkaline Water Electrolysis Using a Low-Cost Sodium Manganate Solid Redox Mediator

As an ideal energy carrier with clean, high efficiency and high energy density (142.351 kJ g-1), hydrogen is the most promising alternative to fossil fuels when it comes to decarbonizing the planet and energy supply. Today, however, the vast majority of hydrogen production occurs through fossil-fuel intensive processes which release vast amounts of CO₂ defeating the promise of decarbonizing the world. Among other hydrogen production processes, hydrogen production by electrolysis of water has broad application prospects as an alternative approach, and is very attractive for green energy development due to its advantages of cleanliness, environmental protection and zero emission.(1) Alkaline water electrolysis has dominated the current electrochemical hydrogen production industry for the past few decades, but issues such as gas product mixing and the use of renewable energy sources (e.g., solar, wind) remain inherent challenges.(2) To this end, in this paper, low-cost Na0.44MnO2 was chosen as a solid redox mediator to decouple the evolution of H2 and O2 in alkaline conditions, which can produce high-purity gas products directly in membrane-less electrolytic cells without gas purification. As an intermediate carrier for charge storage, the decoupling efficiency can reach 97% at a constant current of 2 mA/1.5 cm2. In addition, we performed the evolutionary reactions of hydrogen and oxygen separately under intermittent renewable energy conditions to achieve direct conversion of solar to hydrogen energy, which greatly enhances the flexibility of hydrogen production and further confirms the potential practical application of Na0.44MnO2. Figure 1. (a) CV curve of the Na0.44MnO2 electrode, and LSV curves of the Pt electrode for the HER and the RuO2/IrO2 electrode for the OER at a scan rate of 1 mV s-1 in 1M NaOH. (b) The charging/discharging curves of the Na0.44MnO2 electrode at different current densities. (c) Decoupled water electrolysis with Na0.44MnO2 electrode. (d) The stability performance of the separate H2/O2 generation at a current of 5 mA with a step time of 400 s. (e) Hydrogen purity test. Reference M. G. Schultz, T. Diehl, G. P. Brasseur and W. Zittel, science, 302, 624 (2003).M. Carmo, D. L. Fritz, J. Mergel and D. Stolten, International journal of hydrogen energy, 38, 4901 (2013).

Overview of glycerol as a carbon source in the hydrogen production process

Overview of glycerol as a carbon source in the hydrogen production process

(Invited) Leveraging Magnetohydrodynamic Mechanisms for Stable and Efficient Microgravity Electrolysis

Water electrolysis is the fundamental chemical process for oxygen and hydrogen production in space. It is widely employed in modern environmental control and life support systems, propulsion technologies, and high-density energy storage devices. Furthermore, future interplanetary missions are likely to employ water as a commodity acquired and processed by In Situ Resource Utilization (ISRU) methodologies to produce propellants, thereby reducing vehicle launch mass.The absence of buoyancy results in major technical challenges for the operation of electrolytic cells in low gravity. The need to detach and collect oxygen and hydrogen bubbles has been traditionally addressed by means of forced water recirculation loops. However, this leads to complex, inefficient, and unreliable liquid management devices composed of multiple elements and moving parts. Two distinct magnetohydrodynamic (MHD) mechanisms may instead be employed to induce phase separation: diamagnetic, and Lorentz forces. The former arises in the presence of strong, inhomogeneous magnetic fields and results in a magnetic buoyancy effect. The latter is a consequence of the imposition of a magnetic field to the current generated between two electrodes. Both approaches can potentially lead to a new generation of electrolytic cells with minimum or no moving parts, hence enabling the human deep space operations with minimum mass and power penalties.Dedicated microgravity experiments are required to study these novel magnetically enhanced electrolysis concepts. This presentation introduces the fundamentals of both methods and discusses the experimental design and results from several experimental campaigns at ZARM’s drop tower and Blue Origin’s New Shepard. The performance of representative electrolytic cells subject to different MHD regimes is addressed from an electrochemical and fluid dynamic perspectives. It is demonstrated that the MHD force effectively detaches and collects gas bubbles in microgravity while increasing the current density and improving the stability of the electrolytic cell. Ultimately, this opens the door for the development of highly-efficient space electrolytic cells with applications to human and robotic space exploration.