Continuous Hydrogen Production Research Articles

Magnesium implantation as a continuous hydrogen production generator for the treatment of myocardial infarction in rats

Molecular hydrogen is an emerging broad-spectrum antioxidant molecule that can be used to treat myocardial infarction (MI). However, with hydrogen inhalation, the concentration that can be reached within target organs is low and the duration of action is short, which makes it difficult to achieve high dose targeted delivery of hydrogen to the heart, seriously limiting the therapeutic potential of hydrogen for MI. As a result of reactions with the internal environment of the body, subcutaneous implantation of magnesium slices leads to continuous endogenous hydrogen production, leading to a higher hydrogen concentration and a longer duration of action in target organs. In this study, we propose magnesium implant-based hydrogen therapy for MI. After subcutaneous implantation of magnesium slices in the dorsum of rats, we measured hydrogen production and efficiency, and evaluated the safety of this approach. Compared with hydrogen inhalation, it significantly improved cardiac function in rats with MI. Magnesium implantation also cleared free radicals that were released as a result of mitochondrial dysfunction, as well as suppressing cardiomyocyte apoptosis.

Enhancing bioelectrochemical hydrogen production from industrial wastewater using Ni-foam cathodes in a microbial electrolysis cell pilot plant

Microbial electrolysis cells (MECs) have garnered significant attention as a promising solution for industrial wastewater treatment, enabling the simultaneous degradation of organic compounds and biohydrogen production. Developing efficient and cost-effective cathodes to drive the hydrogen evolution reaction is central to the success of MECs as a sustainable technology. While numerous lab-scale experiments have been conducted to investigate different cathode materials, the transition to pilot-scale applications remains limited, leaving the actual performance of these scaled-up cathodes largely unknown. In this study, nickel-foam and stainless-steel wool cathodes were employed as catalysts to critically assess hydrogen production in a 150 L MEC pilot plant treating sugar-based industrial wastewater. Continuous hydrogen production was achieved in the reactor for more than 80 days, with a maximum COD removal efficiency of 40 %. Nickel-foam cathodes significantly enhanced hydrogen production and energy efficiency at non-limiting substrate concentration, yielding the maximum hydrogen production ever reported at pilot-scale (19.07 ± 0.46 L H2 m−2 d−1 and 0.21 ± 0.01 m3 m−3 d−1). This is a 3.0-fold improve in hydrogen production compared to the previous stainless-steel wool cathode. On the other hand, the higher price of Ni-foam compared to stainless-steel should also be considered, which may constrain its use in real applications. By carefully analysing the energy balance of the system, this study demonstrates that MECs have the potential to be net energy producers, in addition to effectively oxidize organic matter in wastewater. While higher applied potentials led to increased energy requirements, they also resulted in enhanced hydrogen production. For our system, a conservative applied potential range from 0.9 to 1.0 V was found to be optimal. Finally, the microbial community established on the anode was found to be a syntrophic consortium of exoelectrogenic and fermentative bacteria, predominantly Geobacter and Bacteroides, which appeared to be well-suited to transform complex organic matter into hydrogen.

Specific Organic Loading Rate Control for Improving Fermentative Hydrogen Production

Inhibiting homoacetogens is one of the main challenges in fermentative hydrogen production because these hydrogen consumers have similar growth features to hydrogen producers. Homoacetogens have been related to the excessive accumulation of biomass in fermentative reactors. Therefore, a suitable food/microorganism ratio has the potential to minimize the homoacetogenic activity. In this work, the specific organic loading rate (SOLR) was controlled in two fermentative fixed-bed up-flow reactors through scheduled biomass discharges. Reactors were differentiated by the bed arrangement, namely, packed and structured conformation. The SOLR decay along the time in both reactors was previously simulated according to the literature data. The volume and volatile suspended solids (VSS) concentration of discharges was estimated from the first discharge, and then additional discharges were planned. Biomass discharges removed 21% of the total biomass produced in the reactors, maintaining SOLR values of 3.0 ± 0.4 and 3.9 ± 0.5 g sucrose g−1 VSS d−1 in the packed-bed and structured-bed reactors, respectively. Such a control of the SOLR enabled continuous and stable hydrogen production at 2.2 ± 0.2 L H2 L−1 d−1 in the packed-bed reactor and 1.0 ± 0.3 L H2 L−1 d−1 in the structured-bed one. Controlling biomass was demonstrated to be a suitable strategy for keeping the continuous hydrogen production, although the fermentative activity was impaired in the structured-bed reactor. The homoacetogenic was partially inhibited, accounting for no more than 30% of the total acetic acid produced in the reactor. Overall, the high amount of attached biomass in the packed-bed reactor provided more robustness to the system, offsetting the periodic suspended biomass losses via the planned discharges. Better characterizing both the VSS composition (aiming to differentiate cells from polymeric substances) and the bed hydrodynamics could be useful to optimize the online SOLR control.

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.

Round-the-Clock and Continuous Generation of Hydrogen and Oxygen

The main methods of industrial hydrogen production are: steam restructuring of methane and natural gas; coal gasification; biotechnology; water electrolysis. The most efficient method for producing pure hydrogen and oxygen is to produce pure hydrogen and oxygen in a photoelectrochemical cell. A photoelectrochemical cell produces hydrogen and oxygen directly from solar energy. In a photoelectrochemical cell, a combined anode, made from silicon semiconductor and metal mesh with large cells, submerged in water electrolyte solution, agitated by four photons of light, forms an oxygen molecule, which in the form of a gas bubble lifts from the surface of anode to the free surface of the water electrolyte solution. Two hydrogen cations, formed because of the dissociation of water, reaching the cathode, form a gaseous hydrogen molecule, which, turn into an electrolysis bubble, lifts from surface of cathode to the free surface of the water electrolyte solution. The article presents a new method for round-the-clock and continuous generation of hydrogen and oxygen, using a developed photoelectrolyzer-generator, taking a horizontally located combine anode, made from silicon semiconductor and metal mesh with large cells and burnt graphite cathode (electrolysis base) at the bottom of the photoelectrolyzer-generator; a membrane from fire hose material, located between electrodes; device, regulating the gap between the electrodes. Round-the-clock and continuous production of hydrogen and oxygen in the photoelectrolyzer-generator is ensured by using lamp, including LED with a daylight battery charger as a useful electrical load, which brightens the combined anode, made from silicon semiconductor and metal mesh with large cells at night until the morning and by continuously filling the photoelectrolyzer-generator with water.

Pilot composite tubular bioreactor for outdoor photo-fermentation hydrogen production: From batch to continuous operation

A novel 70 L composite tubular photo-bioreactor was constructed, and its photo-fermentation hydrogen production characteristics of batch and continuous modes were investigated with glucose as the substrate in an outdoor environment. In the batch fermentation stage, the hydrogen production rate peaked at 37.6 mL H2/(L·h) accompanied by a high hydrogen yield of 7 mol H2/mol glucose. The daytime light conversion efficiency is 4 %, with 37 % of light energy from the sun. An optimal hydraulic retention time of 5 d was identified during continuous photo-fermentation. Under this condition, the stability of the cell concentration is maintained and more electrons can be driven to the hydrogen generation pathway while attaining a hydrogen production rate of 20.7 ± 0.9 mL H2/(L·h). The changes of biomass, volatile fatty acids concentration and ion concentration during fermentation were analyzed. Continuous hydrogen production by composite tubular photo-bioreactor offers new ideas for the large-scale deployment of photobiological hydrogen production.

A stable flow hydrogen production of sodium borohydride hydrolysis using millimeter-scale Ru/Al2O3 spheres as catalyst

In this study, we investigated the performance of continuous flow hydrogen production from NaBH4 hydrolysis by loading Ru onto millimeter-scale Al2O3 spheres (0.5–1 mm in diameter) (Ru/m-Al2O3) using a simple impregnation method. The results from transmission electron microscopy (TEM) and N2 adsorption and desorption revealed that Ru particles, with an average size of 2.73 nm, were evenly distributed on the Al2O3 spheres, and the catalysts exhibited a typical mesoporous structure. The study investigated the impact of Ru loading, catalyst quantity, catalyst reduction temperature, hydrogen production temperature, feeding rate, and concentrations of NaBH4 and NaOH on the rate of hydrogen production (HPR). The evaluation of hydrogen production revealed that the top-performing Ru/m-Al2O3 catalyst achieved a HPR of 22.44 L min–1 gRu–1 at 30 °C, with an apparent activation energy (Ea) of 33.98 kJ mol–1. The catalyst could continuously produce hydrogen for 1700 min with a 20 % decrease in activity. The characterization results before and after hydrogen production revealed that Ru/m-Al2O3 exhibited excellent structural stability after a prolonged period of hydrogen production, with no apparent changes in its morphology, crystal structure, Ru particle size, and pore structure. In addition, the X-ray diffraction (XRD), inductively coupled plasma optical emission spectrometry (ICP-OES), and hydrogen production performance results showed that the flow system could effectively prevent the aggregation of NaBO2 on the catalyst's surface, thereby significantly improving the hydrogen production activity.

P-Ni co-doped Mo2C embedded in carbon-fiber paper as a highly efficient electrocatalyst for hydrogen evolution in alkaline media

The development of noble-metal-free electrocatalysts with high electrocatalytic performance and stability by adopting a scalable route is key to solving the energy crisis. We report a PNi co-doped Mo2C-based electrocatalyst with high hydrogen evolution reaction (HER) catalytic activity prepared by a molten-salt method. Using phosphating times of 2 h and 4 h yielded P-Ni-Mo2C-2h and P-Ni-Mo2C-4h, respectively, both of which exhibited nanoflower-like structures that provided abundant active sites for the reaction. P-Ni-Mo2C-2h possessed good electrocatalytic properties with a low overpotential of only 140.5 mV at j = 10 mA cm−2 and a small Tafel slope of 50.7 mV dec−1 in an alkaline environment. P-Ni-Mo2C-2h exhibited excellent stability after 20 h of continuous hydrogen production. The use of an excessively long phosphating time caused a narrow down of spaces formed by nanoflakes, thereby reducing the HER performance of the electrocatalyst. The results of this study provide guidelines for the preparation of high-efficiency PNi co-doped electrocatalysts.

Dynamic Modeling of a Solar-To-Hydrogen Flexible High Temperature Steam Electrolysis Plant

Sustainble hydrogen production for use as a renewable combustible fuel and clean chemical feedstock is an important objective as the world moves towards a renewable energy future. High temperature steam electrolysis is a promising hydrogen production technology due to its reduced electric input that is offset by heat input into steam generation and steam superheating. An option to provide this heat is to use concentrating solar thermal technology that can sustainably provide heat input while renewable electricity is used for the electrolysis reaction. In this work, a solar-to-hydrogen high temperature steam electrolysis plant is designed and dynamically modeled, showing continuous hydrogen production by utilizing supplemental heating and efficient recuperative heating from the electrolysis product streams. Through this design, over 90% of the required heat input for the process can by met by a combination of solar and recuperative heat. Additionally, the plant can flexibility operate by ramping down hydrogen production and through flexible heat integration, which intelligently integrates solar heat based on solar conditions. Smooth operation with flexible hydrogen production is demonstrated which decreases electrical input during on-peak grid times and also decreases the total supplemental heat load over the course of a day from 26.1% to 24.5%. In addition, by using flexible heat integration, the plant can increase its solar heat usage by 4.1% relative to a base case. Both options for flexibility show efficient use of solar thermal energy to sustainably and continuously produce hydrogen.

Simultaneous and Continuous Production of Carbon Nanotubes and Hydrogen by Catalytic CH4 Decomposition in a Pressurized Fluidized-Bed Reactor

Simultaneous and Continuous Production of Carbon Nanotubes and Hydrogen by Catalytic CH₄ Decomposition in a Pressurized Fluidized-Bed Reactor

Experimental investigation on parameter optimization of liquid spectral beam splitter for continuous photocatalytic hydrogen production accompanied with photovoltaic power generation under solar full spectrum

Effective utilization of solar energy is of great significance for a sustainable future. Herein, we report a cascade system for hydrogen-electricity co-production (PH-PV) utilizing solar full spectrum. The output performance of the system can be precisely adjusted by controlling certain parameters of liquid spectral beam splitter (LSBS) which contains TiO2 nanoparticle suspension simultaneously generating hydrogen via a photocatalytic reaction process. Typically, the thickness of LSBS, the loading amount of TiO2, the flowrate of suspension and the light intensity have been investigated in detail. It is found that LSBS is necessary in our system as it could ensure the safe operation of PV while the light intensities larger than 8 suns. With the decrease of the thickness or loading amount of photocatalyst, more electricity could be produced by PV module but less hydrogen from PH module. Further increase of above two parameters simultaneously could lead to aggregation and settlement of particle suspension in LSBS, which is detrimental to the optical absorbance of the system. Besides, changing the flowrate will diversify the surface features of particles by shear-induced effect. At optimal flowrate, the particles in LSBS could exhibit oscillation characteristics under synergistic effect of shear force and gravity, which would lead to excellent light absorption and transmittance. Furthermore, an obvious gain for both hydrogen and electricity output and system efficiency could be obtained through increasing light intensity appropriately. Finally, the improved merit function (MF) was employed to evaluate the performance of hybrid system and more obvious effect of flowrate on MF value than other parameters was found. The optimal MF value of 3.07 was reached when flowrate was 60 mL/min. Our work is expected to provide important guidance for the optimization of PH-PV cascade system driven by outdoor direct solar energy.

Cerium-Organic Framework (CeOF) for hydrogen generation via the hydrolysis of NaBH4

Hydrogen gas has been considered an eco-friendly energy source with a high energy content, making it a suitable energy carrier for several industries. A cerium-organic framework, denoted as CeOF, was synthesized by reacting cerium with a tricarboxylic organic linker using a solvothermal method. The material's characteristics were analyzed using X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and Fourier transforms infrared spectroscopy (FT-IR) to confirm its crystallinity, phase purity, elemental composition, chemical bonding, morphology, and thermal stability. CeOF catalysized the release of hydrogen from solid hydrogen storage materials, e.g., sodium borohydride (NaBH4) by the reaction with water via hydrolysis. An examination was carried out to analyze the influence of catalyst loading, NaBH4 weight (0.2–3 wt%), and reaction temperature. The CeOF catalyst showed a significant hydrogen generation rate (HGR) of 1800 mLH2·gcat-1·min−1, with an activation energy of 58.8 kJ·mol−1. It showed good catalytic recyclability enabling continuous hydrogen production for four cycles without any significant decrease in the material’s performance.

Photofermentative Biohydrogen Production Enhancement with Nanoparticle

This study will explore the use of a biological pathway known as photo fermentation for the production of biohydrogen under anoxic and nitrogen deficient conditions due to its high hydrogen production, and to emphasize the role of a dominating enzyme, the nitrogenase enzyme, in catalyzing the process of hydrogen evolution from a medium composed of Purple Non-Sulfur Bacteria (Rhodopseudomonas Palustris) with glycerol as the substrate. For Purple Non-Sulphur Bacteria, the optimal H2 production temperature ranges between 30 °C to 36 °C. Simultaneously, illumination is applied by LED lights and is varied from no string LED illumination, to single string illumination (240 W/m2), and double string illumination (480 W/m2) to simulate and examine performance in outdoor conditions and achieved a maximum of 428% increase in hydrogen productivity compared to previous studies. Consequently, this suggests that it is economically appealing to use the non-growing R. palustris bacterium as the chosen biocatalyst for continuous hydrogen production. These preliminary results constitute the development of continuous H2 production which evolves into the green fuel of the future production.

Deep learning prediction of photocatalytic water splitting for hydrogen production under natural light based on experiments

Harnessing hydrogen through photocatalytic water splitting represents a pivotal stride towards carbon neutrality. Evaluating ongoing experiments under natural light conditions is critical for scaling this technology. Given the inherent instability of natural light, devising precise hydrogen production forecasts has emerged as a core focus to streamline project timelines and financial governance. This research introduces a robust system for continuous photocatalytic water splitting, leveraging natural light for hydrogen production. Analysis and prognostication of hydrogen generation are conducted using experimental data from 21 distinct groups. Critical factors, including radiation intensity, reaction temperature, reactant concentration, solar concentrator specifics, and hydrogen production rate (HPR), undergo thorough correlation scrutiny. Employing a deep-learning framework, gated recurrent units (GRU) neural network is utilized for nuanced feature apprehension, enhancing hydrogen output forecasting precision. The results illustrate that the mean daily solar-to-hydrogen (STH) energy conversion efficiency across the 21 groups is approximately 0.25 %. Radiation intensity prevails as a significant influencer, with reaction temperature also playing a substantial role. Solar concentrator utilization proves beneficial for augmenting HPR. Nevertheless, the unevenness of solar concentrator presents adverse effects, necessitating consideration during system conceptualization. The optimized prediction model's outcomes align closely with experimental observations, and with a test loss of 2.61 × 10−3 and 682 epochs, the model's predictive superiority is affirmed. The continuous hydrogen production experiments leveraging natural light provide the feasible reference for the large-scale application of this technology. The correlation analysis of critical factors provides the optimization direction for practical engineering design. The hydrogen production prediction model aims to provide scientific basis for the decision-making of this technology.

Iridium Catalyst Immobilized on Crosslinked Polyethyleneimine for Continuous Hydrogen Production Using Formic Acid.

Invited for this month's cover is provided by researchers from National Institute of Advanced Industrial Science and Technology (AIST) in Japan. The image shows the flow type continuous hydrogen production from formic acid and power generation by fuel cell achieved by the iridium catalyst immobilized on crosslinked polyethylene imine. The Research Article itself is available at 10.1002/cssc.202301282.

Front Cover: Iridium Catalyst Immobilized on Crosslinked Polyethyleneimine for Continuous Hydrogen Production Using Formic Acid (ChemSusChem 1/2024)

Front Cover: Iridium Catalyst Immobilized on Crosslinked Polyethyleneimine for Continuous Hydrogen Production Using Formic Acid (ChemSusChem 1/2024)

Continuous Hydrogen Production via Hydrothermal Gasification of Biodiesel Industry Wastewater: Experimental Optimization and Energy Integration Simulation

Continuous Hydrogen Production via Hydrothermal Gasification of Biodiesel Industry Wastewater: Experimental Optimization and Energy Integration Simulation

Iridium Catalyst Immobilized on Crosslinked Polyethyleneimine for Continuous Hydrogen Production Using Formic Acid.

Hydrogen is an alternative fuel that can play a critical role in achieving net zero emissions, leading to global environment sustainability. An iridium-immobilized catalyst based on polyethyleneimine (PEI) was synthesized and utilized for hydrogen production via formic acid dehydrogenation (FADH). Iridium complex is cross-linked with its ligand and PEI to form the immobilized catalyst, where the iridium content could be easily varied in the range of 1-10 %. The structure of the iridium-immobilized catalyst was confirmed using solid-state NMR, DNP NMR, and FTIR spectroscopies. The iridium-immobilized catalyst with PEI showed excellent catalytic activity for FADH, exhibiting the catalyst's highest turnover frequency (TOF) value of 73 200 h-1 and a large turnover number (TON) value of over 1 130 000. The catalyst could be used for continuous hydrogen production via FADH, exhibiting high durability for over 2 000 h with TON value of 332 889 without any degradation in catalytic activity. The obtained hydrogen gas was evaluated for power generation using a standard fuel cell, as well as achieved 5 h of stable power generation.

Swept open moving particle reactor including heat recovery for solar thermochemical fuel production

Green hydrogen can be produced by thermochemical redox cycles utilizing concentrated solar energy. A high solar-to-fuel efficiency, as well as a robust system design, is crucial. As lacking heat recovery and ineffective use of the redox material significantly reduce the efficiency, the authors developed a particle based concept incorporating these requirements. A central component is a solid–fluid direct contact heat exchanger in which the sweep gas reduces the countercurrent moving particles. Besides that, a key feature is the continuous production of hydrogen due to a locally separated reduction and oxidation step. The amount of technical challenging reactor parts is reduced, since the concept does not require a window and high temperature vacuum. A steady state modeling approach leads to an evaluation of the whole concept. The reduction reaction, a simplified oxidation process and several parasitic losses are included. By this means, the energy share and the solar-to-fuel efficiency is calculated. Depending on the heat exchanger effectiveness, the results indicate solar-to-fuel efficiencies in the range of 4.2 to 18.7% for the non-optimized base case design.

Valorization of sugarcane leaves and co-digestion with microalgal biomass to produce biofuels and value-added products under the circular economy and zero-waste concepts

This study investigates the production of biofuels and value-added products by co-digesting sugarcane leaves and microalgal biomass, aligning with circular economy and zero-waste principles. Hydraulic retention time (HRT) on continuous hydrogen production in a continuous stirred tank reactor was investigated. An optimal HRT of 12 h maximizes hydrogen production rate (3,983 mL-H2/L·d) and yield (99.6 mL-H2/g-VS). Microbial analysis using 16S rRNA amplicon sequencing on the Illumina platform indicates diverse communities, prominently featuring Streptococcus (43.4 %) and Clostridium (31.3 %) genera. The process efficiently utilizes residual components—acidified slurry, hydrogenic effluent, and solid residue—for methane and hydrogen generation, yielding up to 22.2 kJ/g-VS in total energy. The solid residue from hydrogen production exhibits composting properties and serves to produce vermicompost and densified refuse-derived fuel. This approach exemplifies the adept utilization of raw materials within a circular economy and zero-waste framework, yielding no waste throughout the entire process.