Hydrogen Generation System Research Articles

The value of diurnal and seasonal energy storage in baseload renewable energy systems: A case study of Ras Ghareb – Egypt

In the current work, a model has been developed using MATLAB along with artificial neural network (ANN) to optimally configure a hybrid renewable energy plant. This enabled to use a group of professional software for the design of the plant, and meanwhile conduct an optimization study for the plant configuration. The proposed plant is capable of producing a steady output to the grid at the least Levelized Cost of Electricity (LCOE), with minimum Loss of Power Supply Probability (LPSP) and excess energy. The plant consists of a wind farm, a solar PV plant, and a storage section containing Vanadium Redox Flow Batteries (VRFB) and hydrogen generation and storage system for running a Fuel Cell. Ras Ghareb site in Egypt is selected to prove the concept of the hybrid plant based on its favoured solar and wind resources and their complementarity. It has been found that the optimized hybrid combination of a baseload plant of an accredited capacity 200 MW will have 89 % of its output of electricity from direct renewable resources (Wind and PV), 8 % from FC, and 3 % from VRFB. The economic indicators show that the LCOE will be 0.0897$/kWh, at Zero LPSP and Zero Excess energy above the accredited capacity. Relaxing the LPSP by 1 % reduces the system total capital expenditure (CAPEX), and hence, the LCOE by 18.6 % down to 0.073 $/kWh. Seasonal storage has a great effect on the system's steady output and reliability, as both wind and PV potential are less in winter at the selected site. In addition, seasonal energy storage is the major cost driver in the hybrid system, causing baseload generation cost to exceed the conventional thermal baseload units, despite being cheaper than concentrated solar power (CSP). Hydrogen storage is favoured over batteries for seasonal storage due to its advantage for long term storage at relatively lower specific cost.

Aluminium – Water hydrogen generator for domestic and mobile application

The study reports a novel hydrogen generation system. The system comprises Al based hydrogen generating composition with a reduced content of activating additives and an original fully automated Al-water hydrogen generator with capsule supply of hydrogen generating composition. The hydrogen generating composition was synthesized by means of mechanochemical activation of aluminum powder. Bi − 3.5 wt%. and Sn − 1.5 wt%. were used as activating additives. The combination of the proposed hydrogen generating composition and the design features of the generator made it possible to provide a high rate of hydrogen evolution (more than 30 ml/sec*g) and a hydrogen yield of 95–99 %. A high rate of hydrogen evolution was ensured by maintaining a temperature of at least 70 °C in the reaction zone. The heat of the aluminum oxidation reaction was utilized to maintain the necessary temperature. Based on the obtained experimental data, an assumption about the mechanism of the initial stage of the Al oxidation reaction was made. Some feasibility estimations of the hydrogen generation system are presented as well.

Comparative techno-economic analysis of different PV-assisted direct solar hydrogen generation systems

This work provides a robust technoeconomic analysis of a range of direct solar hydrogen generation (DSHG) systems to understand the opportunities and challenges of deploying DSHG to reduce the cost of renewable hydrogen production.

Optimal design of a coupled photovoltaic–electrolysis-battery system for hydrogen generation

A computational algorithm to model a coupled solar-hydrogen system is presented. The results demonstrated that optimizing the system's cost and hydrogen production rate implicitly ensures the levelized cost of energy is minimized.

A comparison study on methanol reforming catalysts for onboard hydrogen generation

In hydrogen energy applications, methanol is the best fuel that can effectively solve the problem of the storage and transportation of hydrogen. The lowest reforming temperature among hydrocarbons also makes it the best fuel for hydrogen generation. This paper aimed to study and compare four methanolreforming catalysts and screen the best one suitable for the on-board hydrogen generation system. In this study, the in-house single-tube reactor, which can precisely control the temperature by a multistage heater, was applied to study the catalyst performance. Physical and chemical properties of the catalyst, such as methanol conversion rate, hydrogen generation rate, CO selectivity at a different liquid hourly space velocity (LHSV), catalyst density, and optimum reaction temperature, were also systematically studied. The hydrogen generation rate per unit mass of the WEF catalyst is the highest, which reached 0.122 g/h·gcat in 9.23 h-1 LHSV. And the methanol conversion rate in 7.72 h-1 LHSV is 96.74%, and somewhat below the BSF catalyst (97.90% in 7.55 h-1 LHSV). The study indicated that the catalyst made by WEF is the best catalyst for on-board hydrogen generation when comprehensively considering the requirement including the performance and vibration resistance. At the end of this paper, the optimized direction of the four catalyzers is also specified.

Thermodynamic evaluation of a 5 kW kerosene-fueled PEMFC-based cogeneration system: Component-level and system-level analysis

A 5 kW kerosene-fueled proton exchange membrane fuel cell-based cogeneration system consisting of a kerosene steam reforming reactor, pressure swing absorption, combustor, and heat collector is proposed for heating and power production. ASPEN Plus and MATLAB / Simulink jointed simulation models are used to establish an accurate model for the integrated system. Thermodynamic analysis in this study is classified into component-level analysis (parametric analysis) and system-level analysis (conventional and advanced exergy analysis). Parametric analysis reveals that increasing the H2 utilization ratio, improving the reformer pressure, and adding water separators contribute to the thermal efficiency of the integrated system. For example, as the H2 utilization ratio varies from 0.5 to 1.0, the thermal energy efficiency increases from 44.1 % to 47.4 % and the thermal exergy efficiency increases from 41.6 % to 44.7 %. Through system-level analysis, at a water/carbon ratio of 3.0, a reformer temperature of 750 °C, and an H2 utilization of 0.8, the thermal and exergy efficiencies of the system are 46.1 % and 43.4 %. Conventional exergy analysis indicates that fuel cell comprises 44.21 % of the total exergy destruction (9.315 kW), while advanced exergy analyses show that it has the highest avoidable-endogenous exergy destruction (3.567 kW). These exergy analyses suggest that fuel cell results in significant system exergy destruction and should be given priority for modification. Replacing a low-temperature fuel cell with a high-temperature fuel cell is a simple method to reduce the exergy destruction, reducing from 4.79 kW to 4.12 kW, approximately a 14 % reduction, and the exergy efficiency increases from 52.22 % to 55.95 %. The core of this work is to introduce a power and hydrogen generation system, evaluate its performance using an advanced thermodynamic method, and provide a solution to optimize the system.

Deep-learning optimization and environmental assessment of nanomaterial's boosted hydrogen and power generation system combined with SOFC

Renewable energy sources are unquestionably required, given that the world's energy consumption is anticipated to increase significantly in the next decades. Besides, fuel cell converts chemical energy directly into electricity, making it the most efficient and environmentally friendly power source. This study examines the viability of producing electricity using a supercritical CO2 cycle, a methane digester, and a gas turbine. Applying the principles of exergetic balance, mass, energy conservation, and component-specific exergetic balance to each part of the power unit allow for a simulation of the power unit's efficiency. Furthermore, a parametric analysis is performed to establish how the relevant factors will affect the unit's functioning. The optimization algorithms are generated with the help of deep learning methods. It was found that the ratio of the compressor's pressure to the current density was the most crucial element in determining output power. Nanoparticles are used in fuel cells to enhance heat transfer and, thus, the generated power. Through optimization, one might find a product that is both the most cost-effective and energy-efficient option available. Artificial neural networks may be used as a mediator to help expedite the process of reaching optimum performance across several criteria. The optimal settings for the planned power plant are now being determined by studying the correlation between design factors and objective functions. Therefore, the second law's efficiency at its sweet spot was calculated at 61.8%. In the end, the system at its optimum point was found to have an exergo-environmental index of 0.436.

Enhanced hydrogen generation in a combined hybrid cycle using aluminum and cooper oxide nanomaterial based on biomass and vanadium chloride cycle: Optimization based on deep learning techniques and Environmental appraisal

The usage of Nanofluid to enhance heat transfer has been investigated by many researchers in small-scale heat transfers; however, in large-scale power plants, it has not been taken care of. In this research paper, a newly proposed energy system for hydrogen generation based on renewable sources is proposed and analyzed in detail. Unlike other power input systems, the vanadium chloride system generates hydrogen because it uses waste heat. In this regard, the nanoparticles of Al2O3 and CuO are utilized in the main heat exchanger to enhance the heat transfer to the reactor of VCLC to generate more hydrogen. Also, the compound system has the gasifier-based internally fired gas turbine as the main system and can generate hydrogen in a more green way. The optimization based on deep learning methods is applied to seek the highest point of operation by the system. The results exhibit that Al2O3 causes more heat transfer and efficiency enhancement, thus in hydrogen production, causing an increase of 18.5% compared to base fluid and 8.3% compared to CuO in H2 Generation In circumstances when it is optimal, the values for exergetic efficiency and total hydrogen production are 64.5% and 4.5 kg/s respectively. In addition, using a nanofluid heat exchanger and biomass energy reduces CO2 emissions to 0.91 kg/kWh.

Optimal design and flow-field pattern selection of proton exchange membrane electrolyzers using artificial intelligence

The design of a proton exchange membrane (PEM) electrolyzer and various hardware options remain key research areas for green hydrogen production technology. We have proposed an approach to select optimum design factors, including a flow-path design for the PEM electrolyzer using a machine learning (ML) technique for the first time. Efficient multiple ML models employing k-nearest neighbors and decision tree regression approaches predict the optimal hydrogen-generating system design for the PEM electrolyzer cell. The proposed ML model was trained and validated using 1062 design data points. The model predicts 17 parameters of the electrolyzer assembly for five input parameters: the hydrogen production rate, electrode area, anode flow area, cathode flow area, and type of cell design (e.g., single or stack). The model shows an absolute mean square error of 0.31 when compared to the experimental results (e.g., potential), which indicates that the model has excellent reliability. Finally, this study presents that the ML model can predict the optimal design of a PEM electrolyzer for commercial-scale hydrogen production rates at 50–3000 mL/min. This research will contribute to reducing the cost and time required to develop future water electrolyzers for hydrogen production.

Osmotic-Enhanced-Photoelectrochemical Hydrogen Production Based on Nanofluidics

Osmotic-Enhanced-Photoelectrochemical Hydrogen Production Based on Nanofluidics

Test of conductor and semiconductor electrocatalysts in high voltage alkaline electrolyzer as production media for green hydrogen

Despite the restricted success of conductor and semiconductor electrodes in solving hydrogen production problems, they provide a promising alternative to expensive conventional electrodes in water electrolysis investigations. Titanium dioxide (TiO2) and silver (Ag) are widely used as photocatalysts in water splitting systems for hydrogen generation. Though TiO2 is an inactive chemical semiconductor with poor conductivity, it has not been entirely investigated as an electrocatalyst yet. Two criteria were used to achieve this target: supplying high voltage to overcome the TiO2 large band gap and immersing it in an alkaline solution to activate its inert surface. For comparison study, Ag noble metal nanoparticles coating was employed as a competitive electrocatalyst. In this regard, the application of Ag and TiO2 coated on Ti electrodes in a hydrogen production system operated under high voltage was reported. The nanoparticles were synthesized using cost-effective and simple methods based on UV-deposition for Ag nanoparticles and the chemical precipitation method for TiO2 nanoparticles. Then the synthesized nanoparticles were deposited on the Ti electrodes by simple immersion. The synthesized nanoparticles and coated electrodes were tested by XRD, SEM, and EDS to study their morphology, structure, particle size, and surface composition. Based on these results, TiO2 nano-powder and coated electrodes exhibited homogenous spheres with a mixture of rutile and anatase phases, the majority being the anatase phase. The Ag-coated Ti substrate possessed a smaller crystallite size compared to TiO2 coated substrate. To evaluate the performance of Ag/Ti and TiO2/Ti electrodes toward hydrogen production, H2 flow rates were measured in a 3.6 M KOH electrolytic solution at 6 V. Hydrogen flow rates obtained for pure Ti, Ag, and TiO2 electrodes at a steady state were 21, 35, and 37 SCCM (standard cm3/min), respectively. Also, it was found that energy consumption was reduced when the electrodes were coated with nanoparticles. Furthermore, the electrolyzer's performance was assessed by calculating the hydrogen production efficiency and the voltage efficiency. The results showed that using TiO2 electrodes gave the best hydrogen production and voltage efficiencies of 27% and 23%, respectively. This study brings new insights about Ag and TiO2 coated electrodes in alkaline water electrolysis at high voltage regarding nanoparticle performance, hydrogen production, system performance, and energy consumption. In addition, minimizing the fabrication and operation costs of hydrogen production is the major enabler for the broad commercialization of water electrolysis devices.

Dynamic simulation and 3E optimization with an environmental assessment of an efficient energy plant for generation of fresh water by humidification-dehumidification technology and green power and H2

Buildings, mainly residential complexes, can benefit significantly from integrated district generating systems because of their flexibility, increased energy efficiency, and reduced emissions. The energy requirements of a building in Beijing, China, are investigated in this work using dynamic modeling software. The use of solar energy, including photovoltaic thermal panels and collectors, desalination systems, which include humidification and dehumidification units, and hydrogen generation systems, which include alkaline and proton exchange membrane electrolyzer, as well as heating and cooling systems, is suggested and examined transiently. The TRNSYS software works by simulating a situation from a thermodynamic and environmental point of view. According to the findings, we receive solar radiation on our solar panels for more than half the year, with a maximum output of 16.2 kWh. Additionally, it was found that more hydrogen and freshwater were produced during the year's warmer seasons, with the maximum hydrogen production rate reaching 2 kg per hour. The hydrogen tank, therefore, had a higher state of charge during the hotter months. The power and heating produced were also calculated on the hottest and coldest days of the year. The findings showed that power generation is roughly-four times higher on the year's hottest day than the coldest. Furthermore, since freshwater and hydrogen production rates rise during hot weather, the overall efficiency is higher during warm months. After optimization was completed, the best-case scenario saw 0.7 kg of hydrogen produced for 17.45 $/GJ. Environmentally, using solar energy can be reduced CO2 emissions compared with fossil fuels.

(Invited) Efficient and Selective Electrocatalytic and Photoelectrochemical Conversion of Energy and Chemicals

Due to the intermittent nature of most renewable energy sources (such as solar and wind), practical large scale renewable energy utilization demands both efficient energy conversion and large scale energy storage or alternative usage. Earth-abundant but highly active and selective electrocatalysts are needed to enable efficient and sustainable production of fuels and chemicals using electrocatalytic and photoelectrochemical (PEC) energy conversion. We developed earth-abundant electrocatalysts for highly efficient hydrogen evolution reaction (HER) and oxygen evolution (OER). We recently combined computations and experiments to develop metal compounds as selective catalysts for two-electron oxygen reduction reaction (2e- ORR) to produce hydrogen peroxide (H2O2) and the subsequent electro-Fenton process for upgrading biomass molecules. We have integrated these earth-abundant electrocatalysts with efficient semiconductor materials to demonstrate efficient photoelectrochemical hydrogen generation systems. We also developed high performance hybrid solar-charged storage devices that integrate photoelectrochemical solar cells and redox flow batteries (RFBs). In these integrated solar flow batteries (SFBs), solar energy is absorbed by semiconductor electrodes to directly charge up the redox couples without external electric bias. Such charged redox molecules can then be either discharged to generate the electricity when needed or used to produce fuels and chemicals.

Parametric assessment of a novel renewable energy based integrated plant with thermal energy storage for hydrogen generation and cleaner products

Renewable energy-supported multigeneration plants and energy storage systems have important in reducing carbon emissions and also effective use of energy sources. In this study, both a renewable energy source-based energy storage process and a newly developed multigeneration plant are studied through detailed thermodynamic analysis. Here, the energy required for the compressed air storage unit is obtained from the hybrid system of solar and wind energy, and the stored compressed air reacts with natural gas in the Brayton cycle and goes to the multigeneration cycle. Furthermore, the key aim of this research is the examination of a multigeneration system for power, heating, cooling, hot water, and hydrogen generation using energy and exergy efficiency methods. The investigated model includes a thermoelectric generator, an organic Rankine cycle, a hydrogen production and liquefaction unit, a cooling system with an ejector, a Brayton cycle, a Rankine cycle with three turbines, and a compressed air energy storage unit with solar photovoltaic and wind turbines. Moreover, to observe the impact of some substantial design variables on the proposed subsystems and the entire plant’s performance and irreversibility rate, thermodynamic analysis is applied parametrically. In light of assessment findings, the net power generation rate of the entire system is 31,308 kW at 25 °C reference condition. Also, the net hydrogen generation capacity, cooling capacity, and heating capacity of the total plant are 0.0499 kg/s, 3650 kW, and 4281 kW. In conclusion, the energetic and exergetic efficiencies of the entire model are determined as 0.5258 and 0.4867.

Unraveling the facile reproducible modeled approach for bifunctional catalytic decorated polydopamine coated sponge composite for hydrogen generation

Continuous, flexible, and pure hydrogen (H2) gas supply to the portable, and compact shape proton exchange membrane fuel cells and other type of fuel cells is considered as one of the key factor to be solved for researchers. In this research study, we develop the facile strategy to synthesize the novel, multipurpose catalytic decorated polydopamine coated sponge (CDPCS) composite for continuous H2 generation for a long period of time as well as storage of solution within the composite. We explore the most efficient, light weight, hydrophilic commercial sponge, that is, wood pulp sponge (WPS), and binder, that is, polydopamine (PDA). Decoration of platinum nano particles and using of sodium borohydride solution are carried out as a case study by using as-synthesized CDPCS. Various characterization techniques such as scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Brunauer-Emmett-Teller (BET) analysis and energy dispersive X-ray (EDX) analysis are successfully employed to confirm the presence and size of nano particles and successfully coating of PDA layer. Hydrogen production performance of CDPCS with respect to different mass contents of Pt nanoparticles, molar concentration of sodium borohydride and at different temperature is investigated in this research study. An 87% yield of hydrogen generation has been achieved with 18 mg contents of Pt nano particles and 3 M concentration of sodium borohydride at room temperature. We believe that our conducted research study with respect to novel, facile, reproducible designed CDPCS based composites will be highly promising to simplify the hydrogen generation system for rapidly developed portable and wearable electronic devices.

Synergetic one-step synthesis of SiC/SiOC/TiO2 composites for visible-light-driven hydrogen generation from methanol reforming

The photocatalysts area aims for feasible clean-renewable energy generation, targeting new low-cost and straightforward manufacturing of visible light-responsive materials by developing organic and inorganic novel composites. This work shows a novel approach, exploring three widely used commercially available powders (SiC, SiOC, and TiO2) to build a ternary-component system based on the polymer-derived ceramic (PDC) pathway. Furthermore, the results disclose the phases' interplay and synergetic effects that improve the composites' catalytic activity. The interaction between Si and Ti atoms in the composite system decreases the bandgap from 3.2 eV to 2.89 eV, increasing the ceramic yield from 51% to 86% while hindering the TiO2 anatase-to-rutile transformation. The SiC–SiOC–TiO2 interplay boosts the visible-light-driven hydrogen generation through photoreforming for hydrogen generation up to approximately 5-fold compared to pristine TiO2. In addition, the synthesis reported herein provides a straightforward and practical approach by increasing existing catalysts’ activity toward visible-light-driven hydrogen generation systems and facilitates further filtration processes.

The Role of Bio-Electrochemical System for Hydrogen Generation

The Role of Bio-Electrochemical System for Hydrogen Generation

Direct Z-scheme photochemical hybrid systems: Loading porphyrin-based metal-organic cages on graphitic-C3N4 to dramatically enhance photocatalytic hydrogen evolution

The rational design of photochemical molecular device (PMD) and its hybrid system has great potential in improving the activity of photocatalytic hydrogen production. A series of Pd6L3 type metal-organic cages, denoted as MOC-Py-M (M = H, Cu, and Zn), are designed for PMDs by combining metalloporphyrin-based ligands with catalytically active Pd2+ centers. These metal-organic cages (MOCs) are first successfully hybridized with graphitic carbon nitride (g-C3N4) to form direct Z-scheme heterogeneous MOC-Py-M/g-C3N4 (M = H, Cu, and Zn) photocatalysts via π–π interactions. Benefiting from its better light absorption ability, the MOC-Py-Zn/g-C3N4 catalyst exhibits high H2 production activity under visible light (10348 μmol g−1 h−1), far superior to MOC-Py-H/g-C3N4 and MOC-Py-Cu/g-C3N4. Moreover, the MOC-Py-Zn/g-C3N4 system obtains an enhanced turn over number (TON) value of 32616 within 100 h, outperforming the homogenous MOC-Py-Zn (TON of 507 within 100 h), which is one of the highest photochemical hybrid systems based on MOC for visible-light-driven hydrogen generation. This confirms the direct Z-scheme heterostructure can promote effective charge transfer, expand the visible light absorption region, and protect the cages from decomposition in MOC-Py-Zn/g-C3N4. This work presents a creative example that direct Z-scheme PMD-based systems for effective and persistent hydrogen generation from water under visible light are obtained by heterogenization approach using homogeneous porphyrin-based MOCs and g-C3N4 semiconductors.

Self-powered electrolysis systems for sustainable hydrogen generation from natural seawater via a Ni/V2O3 Schottky electrode

Developing novel and efficient techniques for extracting hydrogen from natural seawater sustainably via electrolysis is highly attractive, yet remains a great challenge. Herein, a self-powered electrolysis system (SPES) driven by Mg/seawater batteries (MSBs) with a Ni/V2O3 Schottky electrode is demonstrated for sustainable production of hydrogen from seawater. The Ni/V2O3 Schottky electrode is constructed to serve as the hydrogen evolution reaction (HER) cathode for both the MSBs and seawater electrolysis unit in the SPES, enabling facile seawater HER with 10 and 1000 mA cm−2 at low overpotential of 176 and 649 mV respectively. The MSB with the Ni/V2O3 Schottky cathode delivers a peak power density up to 17.81 mW cm−2. Importantly, the designed SPES achieves a high hydrogen production rate up to 12.42 mL cm−2 h−1 from natural seawater with a high energy conversion efficiency of 80.87 %. This work offers an intriguing technique for in-situ sustainable acquisition of hydrogen from natural seawater.

Liquid organic hydrogen carriers (LOHCs) in the thermochemical waste heat recuperation systems: The energy and mass balances

This paper is presented a concept of thermochemical recuperation of waste heat based on hydrogen extraction from liquid organic hydrogen carriers (LOHC), on the example of methylcyclohexane-toluene system. The advantages of this concept is described, for example, a possibility to use a moderate low temperature of waste heat for generation high-exergy “green” hydrogen fuel. To understand the effect of operating parameters on the energy and mass balance, the thermodynamic analysis was performed. The chemical system for hydrogen generation was analyzed via Gibbs free energy minimization method. The thermodynamic analysis was conducted under various operating conditions: temperature of 100–400 °C, pressure of 1–4 bar. Aspen HYSYS software was used for the energy and mass conservation analysis. Sankey diagram for the energy flows is depicted. The results showed that the maximum energy efficiency the thermochemical waste heat recuperation system have in the temperature range above 300–350 °C. In this temperature range, the effect of pressure on the energy balance is negligible and it is recommended for the thermochemical recuperation system to use LOHC with a pressure of 1.5–2 bar. Based on the analysis, it was concluded that the temperature potential of waste heat for about 300–350 °C is enough for the investigated concept. An analysis of a mass balance showed that the decreasing in condensation temperature leads to a significant increasing in the share of condensed toluene from toluene-hydrogen mixture after a reactor. If temperature of a hydrogen-toluene mixture of 20 °C at pressure above 2 bar about 96% of toluene can be condensed after the first condenser.