Production & Supply Chain

The solar to hydrogen (STH) efficiency of photovoltaic-electrolysis (PV-E) setups is a key parameter to lower the cost of green hydrogen produced. Commercial c-Si solar cells have neared saturation with respect to their efficiency which warrants the need to look at alternative technologies. In this work we report a concentrator photovoltaic-electrolysis (CPV-E) setup with a STH efficiency of 28% at 41 suns (without the use of Fresnel lenses) the highest reported efficiency using an alkaline system to date. Using this as a base case we carried out a detailed techno-economic (TEA) analysis which showed that despite the high cost associated with CPV cells the levelized cost of hydrogen (LCOH) is at $5.9 kg1 close to that from c-Si solar farms ($4.9 kg1 ) primarily due to the high STH efficiency. We also report sensitivity analysis of factors affecting both CPV and alkaline electrolyser systems such as the CPV module efficiency and installed capacity electrolyser stack lifetime operating current density and working hours. Our results indicate that in a scenario where the installed capacity of CPV technology matches that of silicon and with an electrolyser operating current density of 0.7 A cm2 the LCOH from CPV electrolysis systems can be.

This article provides a techno-economic study on coupled offshore wind farm and green hydrogen production via sea water electrolysis (OWF-H2). Offshore wind energy wind farms (OWF) and water electrolysis (WE) technologies are described. MHyWind (the tool used to perform simulations and optimisations of such plants) is presented as well as the models of the main components in the study. Three case studies focus on offshore wind farms either stand-alone or connected to the grid via export cables coupled with a battery and electrolysis systems either offshore or onshore. Exhaustive searches and optimisations performed allowed for rules of thumb to be derived on the sizing of coupled OWF-H2 plants that minimize costs of hydrogen production (LCoH2 in €/kgH2): Non-connected OWF-H2 coupled to a battery offers the lowest LCoH2 without the costs of H2 transportation when compared to cases where the WE is installed onshore and connected to the OWF. Using a simple power distribution heuristic increasing the number of installed WE allows the system to take advantage of more OWF energy but doesn’t improve plant efficiency whereas a battery always does. Finally within the scope of this study it is observed that power ratios of optimized plant architectures (leading to the lowest LCoH2) are between 0.8-0.9 for PWE/POWF and 0.3-0.35 for PBattery/POWF.

This first episode was inspired by an Innovate UK KTN perspective commenting on the UK government’s Hydrogen Strategy released by the Department of Business Energy and Industrial Strategy (BEIS) in August 2021. Following the publication of this perspective it was very evident to our Innovate UK KTN experts that the uses and challenges of ‘blue’ and ‘green’ hydrogens were generating a strong debate depending on their application areas.

Over a 20-minute discussion Simon Steffan and Sam try to answer the questions: how is hydrogen currently produced? How will it be produced in the future? And how will it fit in with the energy system?

The podcast can be found on their website

The WGS reaction is an exothermic reaction between carbon monoxide and steam to form carbon dioxide and hydrogen. This reaction which has been used industrially for more than 100 years has recently received a great deal of attention from researchers as one of the ways to produce environmentally acceptable hydrogen from fossil fuels in large quantities. For the application of this reaction on an industrial scale the key is choosing the optimal catalysts that can ensure high CO conversion and have a long lifetime under industrial conditions. Therefore new types of catalysts are being developed that meet these requirements better than the Fe- and Cu-based catalysts commonly used in the past. The WGSR on a commercial nickel-based catalyst and a laboratory-prepared copper and cobalt-based catalyst was tested in a laboratory apparatus set up at the University of Chemistry and Technology Prague. The best performance of the laboratory-prepared catalyst was observed for the catalyst with a Cu content of 14.8 wt% and activated in a hydrogen atmosphere. The laboratory-prepared Co-based catalyst showed good WGSR activity in the temperature range of 200–450 ◦C although this was always inferior to that of the Cu-based catalyst. When subjected to the feed gas containing 0.4 mole% H2S the Co-based catalyst showed good resistance to sulphur poisoning. Therefore Co-based catalysts can be considered good sulphur-tolerant intermediate temperature WGSR catalysts.

Given that conversion efficiencies of incident solar radiation to liquid fuels e.g. H2 are of the order of a few percent or less as quantified by ‘solar to hydrogen’ (STH) economically inexpensive and operationally straightforward ways to boost photo-electrochemcial (PEC) H2 production from solar-driven water splitting are important. In this work externally-applied static electric fields have led to enhanced H2 production in an energy-efficient manner with up to ~30–40% increase in H2 (bearing in mind fieldinput energy) in a prototype open-type solar cell featuring rutile/titania and hematite/iron-oxide (Fe2O3) respectively in contact with an alkaline aqueous medium (corresponding to respective relative increases of STH by ~12 and 16%). We have also performed non-equilibrium ab-initio molecular dynamics in both static electric and electromagnetic (e/m) fields for water in contact with a hematite/iron-oxide (0 0 1) surface observing enhanced break-up of water molecules by up to ~70% in the linear-response régime. We discuss the microscopic origin of such enhanced water-splitting based on experimental and simulation-based insights. In particular we external-field direction at the hematite surfaces and scrutinise properties of the adsorbed water molecules and OH– and H3O+ species e.g. hydrogen bonds between water-protons and the hematite surfaces’ bridging oxygen atoms as well as interactions between oxygen atoms in adsorbed water molecules and underlying iron atoms.

An investigation was conducted to determine the effects of operating parameters for various electrode types on hydrogen gas production through electrolysis as well as to evaluate the efficiency of the polymer electrolyte membrane (PEM) electrolyzer. Deionized (DI) water was fed to a single-cell PEM electrolyzer with an active area of 36 cm2 . Parameters such as power supply (50–500 mA/cm2 ) feed water flow rate (0.5–5 mL/min) water temperature (25−80 ◦C) and type of anode electrocatalyst (0.5 mg/cm2 PtC [60%] 1.5 mg/cm2 IrRuOx with 1.5 mg/cm2 PtB 3.0 mg/cm2 IrRuOx and 3.0 mg/cm2 PtB) were varied. The effects of these parameter changes were then analyzed in terms of the polarization curve hydrogen flowrate power consumption voltaic efficiency and energy efficiency. The best electrolysis performance was observed at a DI water feed flowrate of 2 mL/min and a cell temperature of 70 ◦C using a membrane electrode assembly that has a 3.0 mg/cm2 IrRuOx catalyst at the anode side. This improved performance of the PEM electrolyzer is due to the reduction in activation as well as ohmic losses. Furthermore the energy consumption was optimal when the current density was about 200 mA/cm2 with voltaic and energy efficiencies of 85% and 67.5% respectively. This result indicates low electrical energy consumption which can lower the operating cost and increase the performance of PEM electrolyzers. Therefore the optimal operating parameters are crucial to ensure the ideal performance and durability of the PEM electrolyzer as well as lower its operating costs.

The rapid increase in anthropogenic greenhouse gas concentrations in the last several decades means that the effects of climate change are fast becoming the familiar horsemen of a planetary apocalypse. Catalysis one of the pillars of the chemical and petrochemical industries will play a critical role in the effort to reduce the flow of greenhouse gases into the atmosphere. This Special Issue is timely as it provides a collection of high-quality manuscripts in a diverse range of topics which include the production of green hydrogen via water electrolysis the steam reforming of ethanol propane or glycerol the dry reforming of methane and the autothermal reforming of diesel surrogate fuel. The topic of the transformation of biomass waste to chemicals is also well represented as is the tackling of CO₂ emissions via novel utilization technologies. The Editors are grateful to all authors for their valuable contributions and confident that this Special Issue will prove valuable to scholars university professors and students alike.

In the context of the current serious problems related to energy demand and climate change substantial progress has been made in developing a sustainable energy system. Electrochemical hydrogen–water conversion is an ideal energy system that can produce fuels via sustainable fossil-free pathways. However the energy conversion efficiency of two functioning technologies in this energy system—namely water electrolysis and the fuel cell—still has great scope for improvement. This review analyzes the energy dissipation of water electrolysis and the fuel cell in the hydrogen–water energy system and discusses the key barriers in the hydrogen- and oxygen-involving reactions that occur on the catalyst surface. By means of the scaling relations between reactive intermediates and their apparent catalytic performance this article summarizes the frameworks of the catalytic activity trends providing insights into the design of highly active electrocatalysts for the involved reactions. A series of structural engineering methodologies (including nanoarchitecture facet engineering polymorph engineering amorphization defect engineering element doping interface engineering and alloying) and their applications based on catalytic performance are then introduced with an emphasis on the rational guidance from previous theoretical and experimental studies. The key scientific problems in the electrochemical hydrogen–water conversion system are outlined and future directions are proposed for developing advanced catalysts for technologies with high energy-conversion efficiency.

Photocatalytic hydrogen generation is one of the most promising solutions to convert solar power into green chemical energy. In this work a multi-component TiO₂–Ag–Cu₂O composite was obtained through simple impregnation-calcination of Cu₂O and subsequent photodeposition of Ag onto electrospun TiO₂ nanotubes. The resulting TiO₂–Ag–Cu₂O photocatalyst exhibits excellent photocatalytic H₂ evolution activity due to the synergetic effect of Ag and Cu₂O on electrospun TiO₂nanotubes. A dual Z-scheme charge transfer pathway for photocatalytic reactions over TiO₂–Ag–Cu₂O composite was proposed and discussed. This work provides a prototype for designing Z-scheme photocatalyst with Ag as an electron mediator.

The thermochemical water‐splitting method is a promising technology for efficiently con verting renewable thermal energy sources into green hydrogen. This technique is primarily based on recirculating an active material capable of experiencing multiple reduction‐oxidation (redox) steps through an integrated cycle to convert water into separate streams of hydrogen and oxygen. The thermochemical cycles are divided into two main categories according to their operating temperatures namely low‐temperature cycles (<1100 °C) and high‐temperature cycles (<1100 °C). The copper chlorine cycle offers relatively higher efficiency and lower costs for hydrogen production among the low‐temperature processes. In contrast the zinc oxide and ferrite cycles show great potential for developing large‐scale high‐temperature cycles. Although several challenges such as energy storage capacity durability cost‐effectiveness etc. should be addressed before scaling up these technologies into commercial plants for hydrogen production. This review critically examines various aspects of the most promising thermochemical water‐splitting cycles with a particular focus on their capabilities to produce green hydrogen with high performance redox pairs stability and the technology maturity and readiness for commercial use.

Sustainable fuel-range hydrocarbons can be produced via the catalytic decarboxylation of biomass-derived carboxylic acids without the need for hydrogen addition. In this present study 5 wt% platinum on carbon (Pt/C) has been found to be an effective catalyst for hydrothermally decarboxylating butyric acid in order to produce mainly propane and carbon dioxide. However optimisation of the reaction conditions is required to minimise secondary reactions and increase hydrocarbon selectivity towards propane. To do this reactions using the catalyst with varying parameters such as reaction temperatures residence times feedstock loading and bulk catalyst loading were carried out in a batch reactor. The highest yield of propane obtained was 47 wt% (close to the theoretical decarboxylation yield of 50 wt% on butyric acid basis) corresponding to a 96% hydrocarbon selectivity towards propane. The results showed that the optimum parameters to produce the highest yield of propane from the range investigated were 0.5 g butyric acid (0.57 M aqueous solution) 1.0 g Pt/C (50 mg Pt content) at 300 °C for 1 h. The reusability of the catalyst was also investigated which showed little or no loss of catalytic activity after four cycles. This work has shown that Pt/C is a suitable and potentially hydrothermally stable heterogeneous catalyst for making biopropane a major component of bioLPG from aqueous butyric acid solutions which can be sourced from bio-derived feedstocks via acetone-butanol-ethanol (ABE) fermentation.

Given the limited sources of fossil fuels mankind should find new ways to meet its energy demands. In this regard geothermal and solar energy are acknowledged as reliable safe promising and clean means for this purpose. In this research study a comparative analysis is applied on geothermal and solar-driven multi-generation systems for clean electricity and hydrogen production through energy and exergy assessments. The system consists of an organic Rankine cycle a proton electrolyte membrane electrolyzer and a thermoelectric generator subsystem. The Engineering Equation Solver software has been utilized in order to model the system and obtain the output contours sensitivity analysis and exergy destruction. The results were calculated considering the ambient temperature of Bandar Abbas city as a case study considering the geothermal system due to better performance in comparison to the solar system. According to the sensitivity analysis the turbine efficiency evaporator inlet temperature thermoelectric generator suitability criterion pump efficiency and evaporator inlet mass flow rate are the most influential parameters. Also the exergy analysis showed that the utmost system's exergy destruction is pertinent to the evaporator and the least is related to the pump. In addition the system produces 352816 kWh and 174.913 kg of electrical power and hydrogen during one year.

Founded in 2007 and based in Denmark Green Hydrogen Systems designs and manufactures efficient standardized and modular electrolysers for the production of green hydrogen with renewable energy. Niels-Arne Baden has led the company to the upper echelons of the electrolysis sector and he now leads the company's strategy and and public-facing initiatives as the Vice President for Strategy and Public Affairs. On this episode of the Everything About Hydrogen podcast the EAH team sits down with Niels to talk about the journey of the clean hydrogen sector over the recent decades and its rise to prominence in the transition to a decarbonized energy future and how modular electrolysis fits into that picture.

The podcast can be found on their website

Dark fermentation is an anaerobic digestion process of biowaste used to produce hydrogen- for generation of energy- that however releases high amounts of polluting volatile fatty acids such as acetic acid in the environment. In order for this biohydrogen production process to become more competitive the volatile fatty acids stream can be utilized through conversion to high added-value metabolites such as omega-3 fatty acids. The docosahexaenoic acid is one of the two most known omega-3 fatty acids and has been found to be necessary for a healthy brain and proper cardiovascular function. The main source is currently fish which obtain the fatty acid from the primary producers microalgae through the food chain. Crypthecodinium cohnii a heterotrophic marine microalga is known for accumulating high amounts of docosahexaenoic acid while offering the advantage of assimilating various carbon sources such as glucose ethanol glycerol and acetic acid. The purpose of this work was to examine the ability of a C. cohnii strain to grow on different volatile fatty acids as well as on a pre-treated dark fermentation effluent and accumulate omega-3. The strain was found to grow well on relatively high concentrations of acetic butyric or propionic acid as main carbon source in a fed-batch pH-auxostat. Most importantly C. cohnii totally depleted the organic acid content of an ultra-filtrated dark fermentation effluent after 60 h of fed-batch cultivation therefore offering a bioprocess not only able to mitigate environmental pollutants but also to provide a solution for a sustainable energy production process. The accumulated docosahexaenoic acid content was as high as 29.8% (w/w) of total fatty acids.

In this paper a method of efficient hydrogen production using low‐power electrolysis based on pre‐magnetic polarization was proposed in order to improve the rate of hydrogen produc‐ tion by water electrolysis with reduced energy consumption molecular polarity and stress–strain characteristics of distilled water under the condition of a pre‐magnetic field. By constructing a mi‐ crophysical model of hydrogen proton energy‐level transition and a macroscopic mathematical model corresponding to magnetization vector‐polarization hydrogen proton concentration in the pre‐magnetic field the ionic conductivity electrolyte current density interelectrode voltage and hydrogen production efficiency under a varying magnetic field were qualitatively and quantita‐ tively analyzed. In addition an adjustable pre‐magnetic polarization hydrolyzing hydrogen pro‐ duction test platform was set up to verify the effectiveness of the proposed method. The repeated test results within a magnetic field strength range of 0–10000 GS showed that the conductivity of distilled water after pre‐magnetic polarization treatment increased by 2–3 times the electrolytic current density of the PEM (Proton Exchange Membrane) increased with increasing magnetic field strength the voltage between the poles continuously decreased and the hydrogen production rate was significantly improved. When the magnetic field strength reached 10000 GS the rate of hydro‐ gen production by the electrolysis of distilled water increased by 15%–20% within a certain period of time.

The study of the viability of hydrogen production as a sustainable energy source is a current challenge to satisfy the great world energy demand. There are several techniques to produce hydrogen either mature or under development. The election of the hydrogen production method will have a high impact on practical sustainability of the hydrogen economy. An important profile for the viability of a process is the calculation of energy and exergy efficiencies as well as their overall integration into the circular economy. To carry out theoretical energy and exergy analyses we have estimated proposed hydrogen production using different software (DWSIM and MATLAB) and reference conditions. The analysis consolidates methane reforming or auto-thermal reforming as the viable technologies at the present state of the art with reasonable energy and exergy efficiencies but pending on the impact of environmental constraints as CO2 emission countermeasures. However natural gas or electrolysis show very promising results and should be advanced in their technological and maturity scaling. Electrolysis shows a very good exergy efficiency due to the fact that electricity itself is a high exergy source. Pyrolysis exergy loses are mostly in the form of solid carbon material which has a very high integration potential into the hydrogen economy.

Microbial electrolysis cells (MECs) have attracted significant interest as sustainable green hydrogen production devices because they utilize the environmentally friendly biocatalytic oxidation of organic wastes and electrochemical proton reduction with the support of relatively lower external power compared to that used by water electrolysis. However the commercialization of MEC technology has stagnated owing to several critical technological challenges. Recently many attempts have been made to utilize nanomaterials in MECs owing to the unique physicochemical properties of nanomaterials originating from their extremely small size (at least <100 nm in one dimension). The extraordinary properties of nanomaterials have provided great clues to overcome the technological hurdles in MECs. Nanomaterials are believed to play a crucial role in the commercialization of MECs. Thus understanding the technological challenges of MECs the characteristics of nanomaterials and the employment of nanomaterials in MECs could be helpful in realizing commercial MEC technologies. Herein the critical challenges that need to be addressed for MECs are highlighted and then previous studies that used nanomaterials to overcome the technological difficulties of MECs are reviewed.

Hydrogen (H2) is widely viewed as critical to the decarbonization of industry and transportation. Water electrolysis powered by renewable electricity commonly referred to as green H2 can be used to generate H2 with low carbon dioxide emissions. Herein we analyze the critical mineral and energy demands associated with green H2 production under three different hypothetical future demand scenarios ranging from 100–1000 Mtpa H2. For each scenario we calculate the critical mineral demands required to build water electrolyzers (i.e. electrodes and electrolyte) and to build dedicated or additional renewable electricity sources (i.e. wind and solar) to power the electrolyzers. Our analysis shows that scaling electrolyzer and renewable energy technologies that use platinum group metals and rare earth elements will likely face supply constraints. Specifically larger quantities of lanthanum yttrium or iridium will be needed to increase electrolyzer capacity and even more neodymium silicon zinc molybdenum aluminum and copper will be needed to build dedicated renewable electricity sources. We find that scaling green H2 production to meet projected netzero targets will require ~24000 TWh of dedicated renewable energy generation which is roughly the total amount of solar and wind projected to be on the grid in 2050 according to some energy transition models. In summary critical mineral constraints may hinder the scaling of green H2 to meet global net-zero emissions targets motivating the need for the research and development of alternative lowemission methods of generating H2

Hydrogen is envisaged to play a major role in decarbonizing our future energy systems. Hydrogen is ideal for storing renewable energy over longer durations strengthening energy security. It can be used to provide electricity renewable heat power long-haul transport shipping and aviation and in decarbonizing several industrial processes. The cost of green hydrogen produced from renewable via electrolysis is dominated by the cost of electricity used. Operating electrolyzers only during periods of low electricity prices will limit production capacity and underutilize high investment costs in electrolyzer plants. Hydrogen production from deep offshore wind energy is a promising solution to unlock affordable electrolytic hydrogen at scale. Deep offshore locations can result in an increased capacity factor of generated wind power to 60–70% 4–5 times that of onshore locations. Dedicated wind farms for electrolysis can use the majority >80% of the produced energy to generate economical hydrogen. In some scenarios hydrogen can be the optimal carrier to transport the generated energy onshore. This review discusses the opportunities and challenges in offshore hydrogen production using electrolysis from wind energy and seawater. This includes the impact of site selection size of the electrolyzer and direct use of seawater without deionization. The review compares overall electrolysis system efficiency cost and lifetime when operating with direct seawater feed and deionized water feed using reverse osmosis and flash evaporation systems. In the short to medium term it is advised to install a reverse osmosis plant with an ion exchanger to feed the electrolysis instead of using seawater directly.

Hydrogen produced by water electrolysis using renewable energy is a sustainable alternative to steam reformation. As a nascent commercial technology performance and economic comparisons of anion exchange membrane water electrolyzers (AEMWE) to other electrolyzer technology benchmarks are not available. We present a techno-economic model estimating AEMWE's baseline levelized cost of hydrogen (LCOH) at $5.79/kg considering trade-offs between current density efficiency stability capital and operating costs. The optimal current density is 1.38 A cm2 balancing stability and performance for the lowest LCOH. Using low-cost electricity and larger stack sizes AEMWE could achieve $2/kg low-carbon hydrogen. Technical improvements targeting system efficiency particularly reducing overpotentials in hydrogen and oxygen evolution reactions could further reduce LCOH to $1.29/kg approaching U.S. Department of Energy cost targets. There are hopes this model could raise the profile of AEMWE's economic potential to produce green hydrogen and highlight its suitability for decarbonizing the energy sector.

Water electrolysis using a proton exchange membrane (PEM) holds substantial promise to produce green hydrogen with zero carbon discharge. Although various techniques are available to produce hydrogen gas the water electrolysis process tends to be more cost-effective with greater advantages for energy storage devices. However one of the challenges associated with PEM water electrolysis is the accumulation of gas bubbles which can impair cell performance and result in lower hydrogen output. Achieving an in-depth knowledge of bubble dynamics during electrolysis is essential for optimal cell performance. This review paper discusses bubble behaviors measuring techniques and other aspects of bubble dynamics in PEM water electrolysis. It also examines bubble behavior under different operating conditions as well as the system geometry. The current review paper will further improve the understanding of bubble dynamics in PEM water electrolysis facilitating more competent inexpensive and feasible green hydrogen production.

An exemplary techno-economic and environmental assessment of carbon-negative hydrogen (H2) production is carried out in this work. It is based on the so-called “dark photosynthesis” with carbon dioxide (CO2) capture and geological storage. As a special feature of the assessment the economic consequences due to the impact on the global climate are taken into account. The results indicate that the example project would be capable of generating negative GHG emissions under the assumptions made. The amount is estimated to be 17.72 kgCO2 to be removed from the atmosphere per kilogram of H2 produced. The levelized costs of carbon-negative hydrogen are obtained considering the economic impact of greenhouse gas emissions and removals. They are estimated to be 0.013 EUR/kWhH2. Compared to grey hydrogen from natural gas (0.12 EUR/kWhH2) and green hydrogen from electrolysis using renewable electricity (0.18 EUR/kWhH2) this shows a potential environmental-economic advantage of the considered example. Even without internalization of GHG impacts an economic advantage of the project (0.12 EUR/kWhH2) over green hydrogen (0.17 EUR/kWhH2) is indicated. Compared to other NETs the GHG removal efficiency is at the lower end of both BECCS and DACCS approaches.

This paper presents a novel dynamic simulation model for assessing the energy performance of solar-driven systems employed in green hydrogen production. The system consists of a parabolic dish collector that focuses solar radiation on two cerium-based thermochemical reactors. The model is based on a transient finitedifference method to simulate the thermal behaviour of the system and it integrates a theoretical analysis of materials and operating principles. Different empirical data were considered for experimentally validating it: a good agreement between experimental and simulated results was obtained for the temperatures calculated inside the thermochemical reactor (R2 = 0.99 MAPE = 6.3%) and the hourly flow rates of hydrogen oxygen and carbon monoxide (R2 = 0.96 MAPE = 10%) inside the thermochemical reactor. The model was implemented in a MatLab tool for the system dynamic analysis under different boundary conditions. Subsequently to explore the capability of this approach the developed tool was used for analysing the examined device operating in twelve different weather zones. The obtained results comprise heat maps of specific crucial instants and hourly dynamic trends showing redox reaction cycles occurring into the thermochemical reactors. The yearly hydrogen production ranges from 1.19 m3 /y to 1.64 m3 /y according to the hourly incident solar radiations outdoor air temperatures and wind speeds. New graphic tools for rapid feasibility studies are presented. The developed tools and the obtained results can be useful to the basic design of this technology and for the multi-objective optimization of its layout and main design/operating parameters.

Solar hydrogen production technology is a key technology for building a clean low-carbon safe and efficient energy system. At present the intermittency and volatility of renewable energy have caused a lot of “wind and light.” By combining renewable energy with electrolytic water technology to produce high-purity hydrogen and oxygen which can be converted into electricity the utilization rate of renewable energy can be effectively improved while helping to improve the solar hydrogen production system. This paper summarizes and analyzes the research status and development direction of solar hydrogen production technology from three aspects. Energy supply mode: the role of solar PV systems and PT systems in this technology is analyzed. System control: the key technology and system structure of different types of electrolytic cells are introduced in detail. System economy: the economy and improvement measures of electrolytic cells are analyzed from the perspectives of cost consumption efficiency and durability. Finally the development prospects of solar hydrogen production systems in China are summarized and anticipated. This article reviews the current research status of photovoltaic-photothermal coupled electrolysis cell systems fills the current research gap and provides theoretical reference for the further development of solar hydrogen production systems.

Hydrogen produced using renewable energy from offshore wind provides a versatile method of energy storage and power-to-gas concepts. However few dedicated floating offshore electrolyser facilities currently exist and therefore conditions of the offshore environment on hydrogen production cost and efficiency remain uncertain. Therefore this review focuses on the conversion of electrical energy to hydrogen using water electrolysis located in offshore areas. The challenges associated with the remote locations fluctuating power and harsh conditions are highlighted and recommendations for future electrolysis system designs are suggested. The latest research in polymer electrolyte membrane alkaline and membraneless electrolysis are evaluated in order to understand their capital costs efficiency and current research status for achieving scaled manufacturing to the GW scale required in the next three decades. Operating fundamentals that govern the performance of each device are investigated and future recommendations of research specifically for the integration of water electrolysers with offshore wind turbines is presented.

The reliability of renewable hydrogen supply for off-take applications is critical to the future sustainable energy economy. Integrated water electrolysis can be deployed at distributed municipal wastewater treatment plants (WWTP) creating opportunity for reduction in carbon emissions through direct and indirect use of the electrolysis output. A novel energy shifting process where the co-produced oxygen is compressed and stored to enhance the utilisation of intermittent renewable electricity is analysed. The hydrogen produced can be used in local fuel cell electric buses to replace incumbent diesel buses for public transport. However quantifying the extent of carbon emission reduction of this conceptual integrated system is key. In this study the integration of hydrogen production at a case study WWTP of 26000 EP capacity and using the hydrogen in buses was compared with two conventional systems: the base case of a WWTP with grid electricity consumption offset by solar PV and the community’s independent use of diesel buses for transport and the non-integrated configuration with hydrogen produced at the bus refuelling location operated independently of the WWTP. The system response was analysed using a Microsoft Excel simulation model with hourly time steps over a 12-month time frame. The model included a control scheme for the reliable supply of hydrogen for public transport and oxygen to the WWTP and considered expected reductions in carbon intensity of the national grid level of solar PV curtailment electrolyser efficiency and size of the solar PV system. Results showed that by 2031 when Australia’s national electricity is forecast to achieve a carbon intensity of less than 0.186 kg CO2-e/kWh integrating water electrolysis at a municipal WWTP for producing hydrogen for use in local hydrogen buses produced less carbon emissions than continuing to use diesel buses and offsetting emissions by exporting renewable electricity to the grid. By 2034 an annual reduction of 390 t–CO2–e is expected after changing to the integrated configuration. Considering electrolyser efficiency improvements and curtailment of renewable electricity the reduction increases to 872.8 t–CO2–e.

The main purpose of this paper is the techno-economic analysis of hydrogen production from biogas via steam reforming in a pilot plant. Process flow modeling based on mass and energy balance is used to estimate the total equipment purchase and operating costs of hydrogen production. The pilot plant installation produced 250.67 kg/h hydrogen from 1260 kg/h biomethane obtained after purification of 4208 m3/h biogas using a heat and mass integration process. Despite the high investment cost the plant shows a great potential for biomethane reduction and conversion to hydrogen an attractive economic path with ecological possibilities. The conversion of waste into hydrogen is a possibility of increasing importance in the global energy economy. In the future such a plant will be expanded with a CO2 reduction module to increase economic efficiency and further reduce greenhouse gases in an economically viable manner.

This comparative study examines the potential for green hydrogen production in Europe and the Middle East leveraging 3MWp solar and wind power plants. Experimental weather data from 2022 inform the selection of two representative cities namely Krakow Poland (Europe) and Diyala Iraq (Middle East). These cities are chosen as industrial–residential zones representing the respective regions’ characteristics. The research optimizes an alkaline water electrolyzer capacity in juxtaposition with the aforementioned power plants to maximize the green hydrogen output. Economic and environmental factors integral to green hydrogen production are assessed to identify the region offering the most advantageous conditions. The analysis reveals that the Middle East holds superior potential for green hydrogen production compared to Europe attributed to a higher prevalence of solar and wind resources coupled with reduced land and labor costs. Hydrogen production costs in Europe are found to range between USD 9.88 and USD 14.31 per kilogram in contrast to the Middle East where costs span from USD 6.54 to USD 12.66 per kilogram. Consequently the Middle East emerges as a more feasible region for green hydrogen production with the potential to curtail emissions enhance air quality and bolster energy security. The research findings highlight the advantages of the Middle East industrial–residential zone ‘Diyala’ and Europe industrial–residential zone ‘Krakow’ in terms of their potential for green hydrogen production.

Hydrogen as an energy source has been identified as an optimal pathway for mitigating climate change by combining renewable electricity with water electrolysis systems. Proton exchange membrane (PEM) technology has received a substantial amount of attention because of its ability to efficiently produce high-purity hydrogen while minimising challenges associated with handling and maintenance. Another hydrogen generation technology alkaline water electrolysis (AWE) has been widely used in commercial hydrogen production applications. Anion exchange membrane (AEM) technology can produce hydrogen at relatively low costs because the noble metal catalysts used in PEM and AWE systems are replaced with conventional low-cost electrocatalysts. Solid oxide electrolyzer cell (SOEC) technology is another electrolysis technology for producing hydrogen at relatively high conversion efficiencies low cost and with low associated emissions. However the operating temperatures of SOECs are high which necessitates long startup times. This review addresses the current state of technologies capable of using impure water in water electrolysis systems. Commercially available water electrolysis systems were extensively discussed and compared. The technical barriers of hydrogen production by PEM and AEM were also investigated. Furthermore commercial PEM stack electrolyzer performance was evaluated using artificial river water (soft water). An integrated system approach was recommended for meeting the power and pure water demands using reversible seawater by combining renewable electricity water electrolysis and fuel cells. AEM performance was considered to be low requiring further developments to enhance the membrane’s lifetime.

The perspective of natural hydrogen as a clear carbon-free and renewable energy source appears very promising. There have been many studies reporting significant concentrations of natural hydrogen in different countries. However natural hydrogen is being extracted to generate electricity only in Mali. This issue originates from the fact that global attention has not been dedicated yet to the progression and promotion of the natural hydrogen field. Therefore being in the beginning stage natural hydrogen science needs further investigation especially in exploration techniques and exploitation technologies. The main incentive of this work is to analyze the latest advances and challenges pertinent to the natural hydrogen industry. The focus is on elaborating geological origins ground exposure types extraction techniques previous detections of natural hydrogen exploration methods and underground hydrogen storage (UHS). Thus the research strives to shed light on the current status of the natural hydrogen field chiefly from the geoscience perspective. The data collated in this review can be used as a useful reference for the scientists engineers and policymakers involved in this emerging renewable energy source.

Economical offshore wind developments depend on alternatives for cost-efficient transmission of the generated energy to connecting markets. Distance to shore availability of an offshore power grid and scale of the wind farm may impede export through power cables. Conversion to H2 through offshore electrolysis may for certain offshore wind assets be a future option to enable energy export. Here we analyse the cost sensitivity of offshore electrolysis for harvesting offshore wind in the North Sea using a technology-detailed multi-carrier energy system modelling framework for analysis of energy export. We include multiple investment options for electric power and hydrogen export including HVDC cables new hydrogen pipelines tie-in to existing pipelines and pipelines with linepacking. Existing hydropower is included in the modelling and the effect on offshore electrolysis from increased pumping capacity in the hydropower system is analysed. Considering the lack of empirical cost data on offshore electrolysis as well as the high uncertainty in future electricity and H2 prices we analyse the cost sensitivity of offshore electrolysis in the North Sea by comparing costs relative to onshore electrolysis and energy prices relative to a nominal scenario. Offshore electrolysis is shown to be particularly sensitive to the electricity price and an electricity price of 1.5 times the baseline assumption was needed to provide sufficient offshore energy for any significant offshore electrolysis investments. On the other hand too high electricity prices would have a negative impact on offshore electrolysis because the energy is more valuable as electricity even at the cost of increased wind power curtailment. This shows that there is a window-of-opportunity in terms of onshore electricity where offshore electrolysis can play a significant role in the production of H2 . Pumped hydropower increases the maximum installed offshore electrolysis at the optimal electricity and H2 prices and makes offshore electrolysis more competitive at low electricity prices. Linepacking can make offshore electrolysis investments more robust against low H2 and high electricity prices as it allow for more variable H2 production through storing excess energy from offshore. The increased electrolysis capacity needed for variable electrolyser operation and linepacking is installed onshore due to its lower CAPEX compared to offshore installations.

This paper explores the opportunities for and progress in establishing a social licence to operate (SLO) for CCS in industrial clusters in the UK focusing on the perspectives of key stakeholders. The evolution of narratives and networks relating to geographical clusters as niches for CCS in industrial decarbonisation is evaluated in relation to seven pillars supporting SLO. Evidence is drawn from a combination of cluster mapping documentary analysis and stakeholder interviews to identify the wider contexts underpinning industrial decarbonisation stakeholder networks interaction and communication critical narratives the conditions for establishing trust and confidence different scales of social licence and maintaining a SLO. The delivery of a sustainable industrial decarbonisation strategy will depend on multiple layers of social licence involving discourses at different scales and potentially for different systems (heat transport different industrial processes). Despite setbacks as a result of funding cancellations and changes to government policy the UK is positioned to be at the forefront of CCS deployment. While there is a high ambition and a strong narrative from government of the urgency to accelerate projects involving CCS clear coordinated strategy and funding frameworks are necessary to build confidence that UK policy is both compatible with net zero and economically viable.

Producing clean energy and minimising energy waste are essential to achieve the United Nations sustainable development goals such as Sustainable Development Goal 7 and 13. This research analyses the techno-economic potential of waste heat recovery from multi-MW scale green hydrogen production. A 10 MW proton exchange membrane electrolysis process is modelled with a heat recovery system coupled with an organic Rankine cycle (ORC) to drive the mechanical compression of hydrogen. The technical results demonstrate that when implementing waste heat recovery coupled with an ORC the first-law efficiency of electrolyser increases from 71.4% to 98%. The ORC can generate sufficient power to drive the hydrogen's compression from the outlet pressure at the electrolyser 30 bar up to 200 bar. An economic analysis is conducted to calculate the levelised cost of hydrogen (LCOH) of system and assess the feasibility of implementing waste heat recovery coupled with ORC. The results reveal that electricity prices dominate the LCOH. When electricity prices are low (e.g. dedicated offshore wind electricity) the LCOH is higher when implementing heat recovery. The additional capital expenditure and operating expenditure associated with the ORC increases the LCOH and these additional costs outweigh the savings generated by not purchasing electricity for compression. On the other hand heat recovery and ORC become attractive and feasible when grid electricity prices are higher.

Green hydrogen is considered to be one of the best candidates for fossil fuels in the near future. Bio-hydrogen production from the dark fermentation of organic materials including organic wastes is one of the most cost-effective and promising methods for hydrogen production. One of the main challenges posed by this method is the low production rate. Therefore optimizing the operating parameters such as the initial pH value operating temperature N/C ratio and organic concentration (xylose) plays a significant role in determining the hydrogen production rate. The experimental optimization of such parameters is complex expensive and lengthy. The present research used an experimental data asset adaptive network fuzzy inference system (ANFIS) modeling and particle swarm optimization to model and optimize hydrogen production. The coupling between ANFIS and PSO demonstrated a robust effect which was evident through the improvement in the hydrogen production based on the four input parameters. The results were compared with the experimental and RSM optimization models. The proposed method demonstrated an increase in the biohydrogen production of 100 mL/L compared to the experimental results and a 200 mL/L increase compared to the results obtained using ANOVA.

The intermittency of renewable energy sources necessitates energy storage to meet the full demand and balancing requirements of the grid. Green hydrogen (H2) is a chemical energy carrier that can be used in a flexible manner and store large amounts of energy for long periods of time. This techno-economic analysis investigates H2 production from wind using commercially available desalination and electrolysis units. Proton exchange membrane and alkaline electrolyser units are utilised and compared. The intermittency of wind is examined with comparison against grid-bought electricity. A model is developed to determine the selling price required to ensure profitability over a 10-year period. Firstly where H2 is produced using energy from the grid with electricity purchased when below a specified price point or between specified hours. In the second scenario a wind turbine is owned by the user and the electricity price is not considered while the turbine capital expenditure is. The price of H2 production from wind is found to be comparable with natural gas derived H2 at a larger scale with a minimum selling price calculated to be 4.85 £/kg at a setpoint of 500 kg of H2/hr. At a setpoint of 50 kg of H2/hr this is significantly higher at 12.10 £/kg. In both cases the alkaline electrolyser produced cheaper H2. This study demonstrates an economy of scale with H2 prices decreasing with increased scale. H2 prices are also closely linked to the capital expenditure with the equipment size space and safety identified as limiting factors.

Although alkaline water electrolysis (AWE) is the most widespread technology for hydrogen production by electrolysis its electrochemical and fluid dynamic optimization has rarely been addressed simultaneously using Computational Fluid Dynamics (CFD) simulation. In this regard a two-dimensional (2D) CFD model of an AWE cell has been developed using COMSOL® software and then experimentally validated. The model involves transport equations for both liquid and gas phases as well as equations for the electric current conservation. This multiphysics approach allows the model to simultaneously analyze the fluid dynamic and electrochemical phenomena involved in an electrolysis cell. The electrical response was evaluated in terms of polarization curve (voltage vs. current density) at different operating conditions: temperature electrolyte conductivity and electrode-diaphragm distance. For all cases the model fits very well with the experimental data with an error of less than 1% for the polarization curves. Moreover the model successfully simulates the changes on gas profiles along the cell according to current density electrolyte flow rate and electrode-diaphragm distance. The combination of electrochemical and fluid dynamics studies provides comprehensive information and makes the model a promising tool for electrolysis cell design.

In the face of increasing demand for hydrogen a feasibility study is conducted on its production by using Renewable Energy Resources (RERs) especially from wind and solar sources with the latter preferring photovoltaic technology. The analysis performed is based on climate data for the Province of Brindisi Apulia Italy. The various types of electrolyzers will be analyzed ultimately choosing the one that best suits the case study under consideration. The technical aspect of the land consumption for RER exploitation until 2050 is analyzed for the Italian case of study and for the Apulia Region. For both the 200 MW and 100 MW RER Power Plants an economic analysis is carried out on the opportunities for using hydrogen. In the last part of the economic analysis the trade-off between the high specific investment cost and the Capacity Factor of Wind technologies is also investigated. The results show the affordability of building high-scale Wind Farms harnessing the existing scale economies. The lowest Hydrogen selling price is achieved by the 200 MW Wind Farms equal to 222 €/MWh against 232 €/MWh of the 200 MW Photovoltaic (PV) Farm. Finally the feasibility analysis considers also the greenhouse gas emission reduction by including in the economic analysis the carbon dioxide (CO2) Average Auction Clearing Price leading for the 200 MW Wind Farms to a hydrogen selling price equal to 191.2 €/MWh against 201 €/MWh of the 200 MW Photovoltaic Farm.

Current climate crisis makes the need for reducing carbon emissions more than evident. For this reason renewable energy sources are expected to play a fundamental role. However these sources are not controllable but depend on the weather conditions. Therefore green hydrogen (hydrogen produced from water electrolysis using renewable energies) is emerging as the key energy carrier to solve this problem. Although different properties of hydrogen have been widely studied some key aspects such as the water and energy footprint as well as the technological development and the regulatory framework of green hydrogen in different parts of the world have not been analysed in depth. This work performs a data-driven analysis of these three pillars: water and energy footprint technological maturity and regulatory framework of green hydrogen technology. Results will allow the evaluation of green hydrogen deployment both the current situation and expectations. Regarding the water footprint this is lower than that of other fossil fuels and competitive with other types of hydrogen while the energy footprint is higher than that of other fuels. Additionally results show that technological and regulatory framework for hydrogen is not fully developed and there is a great inequality in green hydrogen legislation in different regions of the world.

This study describes the optimization of a modelling process concerning biogas’ use to generate green hydrogen and electrical power. The Aspen Plus simulation tool is used to model the procedure and the approach employed to limit the emissions of gas from the hydrogen production process will be the CO2 capture method. This technique uses slack lime (Ca(OH)2) to absorb CO2 capture since it is readily available. The study analyzes many critical parameters in the process including the temperature and pressure in the steam reforming (SR) and the water gas shift (WGS) reactions along with the steam to carbon ratio (S/C) to determine how the production of green hydrogen and electrical power will be influenced. Electricity generation is achieved by taking the residual water from the SR WGS carbonation reactions and converting it to the vapour phase allowing the steam to pass through the turbine to generate electricity. To examine the effects of the synchronized critical parameters response surface methodology (RSM) was used thus allowing the optimal operational conditions to be determined in the form of an optimized zone for operation. The result of parameter optimization gave the maximum green hydrogen production of 211.46 kmol/hr and electric power production of 2311.68 kWh representing increases of 34.86% and 5.62% respectively when using 100 kmol/hr of biogas. In addition control structures were also built to control the reactors’ temperature in the dynamic section. The tuning parameters can control the SR and WGS system’s reactor to maintain the system in approximately 0.29 h and 0.32 h respectively.

As the commercialisation of two contrasting solar-powered water splitting devices with lower TRLs of proton exchange membrane (PEM) electrolyser systems and photoelectrochemical (PEC) systems gains momentum the path towards a sustainable H2 economy is taking shape. Ongoing pilot projects and demonstration plants are proving the feasibility and potential of these technologies in real-world applications. However to ensure their success we must confront the critical challenges of cost reduction and efficiency enhancement making green H2 economically competitive with traditional production methods. To achieve this a collaborative effort among academia industry and policymakers is paramount. This comprehensive review begins by examining traditional water electrolysis methods focusing on the production of green H2 through electrochemical splitting. It delves into crucial components and advancements in the PEM systems addressing challenges related to catalysts membranes gas diffusion layers and bipolar plates. The review also explores solar-driven PEC water splitting emphasizing the significance of efficient photoelectrodes and reactor design. Additionally it discusses the integration of photovoltaic cells with electrochemical or PEC systems for higher H2 yield. Commercialisation is underway and this endeavour necessitates a collaborative approach with active involvement from academia industry and policymakers. This collective effort not only propels us towards greener and more sustainable energy solutions but also represents a transformative step in the global journey towards a sustainable and environmentally conscious economy.

Blue hydrogen is viewed as an important energy vector in a decarbonised global economy but its large-scale and capital-intensive production displays economic performance vulnerabities in the face of increased market and regulatory uncertainty. This study analyses flexible (modular) blue hydrogen production plant designs and evaluates their effectiveness to enhance economic performance under uncertainty. The novelty of this work lies in the development of a comprehensive techno-economic evaluation framework that considers flexible centralised and decentralised blue hydrogen plant design alternatives in the presence of irreducible uncertainty whilst explicitly considering the time value of money economies of scale and learning effects. A case study of centralised and decentralised blue hydrogen production for the transport sector in the San Francisco area is developed to highlight the underlying value of flexibility. The proposed methodological framework considers various blue hydrogen plant designs (fixed phased and flexible) and compares them using relevant economic indicators (net present value (NPV) capex value-at-risk/gain etc.) through a detailed Monte Carlo simulation framework. Results indicate that flexible centralised hydrogen production yields greater economic value than alternative designs despite the associated cost-premium of modularity. It is also shown that the value of flexibility increases under greater uncertainty higher learning rates and weaker economies of scale. Moreover sensitivity analysis reveals that flexible design remains the preferred investment option over a wide range of market and regulatory conditions except for high initial hydrogen demand. Finally this study demonstrates that major regulatory and market uncertainties surrounding blue hydrogen production can be effectively managed through the application of flexible engineering system design that protects the investment from major downside risks whilst allowing access to favourable upside opportunities.

This research investigated the suitability of air-to-water generator (AWG) technology to address one of the main concerns in green hydrogen production namely water supply. This study specifically addresses water quality and energy sustainability issues which are crucial research questions when AWG technology is intended for electrolysis. To this scope a reasoned summary of the main findings related to atmospheric water quality has been provided. Moreover several experimental chemical analyses specifically focused on meeting electrolysis process requirements on water produced using a real integrated AWG system equipped with certified materials for food contact were discussed. To assess the energy sustainability of AWGs in green hydrogen production a case study was presented regarding an electrolyzer plant intended to serve as energy storage for a 2 MW photovoltaic field on Iriomote Island. The integrated AWG used for the water quality analyses was studied in order to determine its performance in the specific island climate conditions. The production exceeded the needs of the electrolyzer; thus the overproduction was considered for the panels cleaning due to the high purity of the water. Due to such an operation the efficiency recovery was more than enough to cover the AWG energy consumption. This paper on the basis of the quantity results provides the first answers to the said research questions concerning water quality and energy consumption establishing the potential of AWG as a viable solution for addressing water scarcity and enhancing the sustainability of electrolysis processes in green hydrogen production.

The energy transition's success hinges on the effectiveness to curbing carbon emissions from hard-to-abate sectors. Hydrogen (H2) has been proposed as the candidate vector that could be used to replace fossils in such energy-intensive industries. Despite green H2 via solar-powered water electrolysis being a reality today the overall defossilization of the hard-to-abate sectors by electrolytic H2 would be unfeasible as it relies on the availability of renewable electricity. In this sense the unbiassed photoelectrochemical water splitting (PEC) as inspired by natural photosynthesis may be a promising alternative expected in the long term. PEC could be partly or even completely decoupled from renewable electricity and then could produce H2 autonomously. However some remaining challenges still limit PEC water splitting to operate sustainably. These limitations need to be evaluated before the scaling up and implementation. A prospective life cycle assessment (LCA) has been used to elucidate a positive performance scenario in which the so-called super-green H2 or photo-H2 could be a sustainable alternative to electro-H2. The study has defined future scenarios by conducting a set of sensitivity assessments determining the figures of operating parameters such as i) the energy to produce the cell; ii) solar-to-hydrogen efficiency (STH); and iii) lifetime. These parameters have been evaluated based on two impact categories: i) Global Warming Potential (GWP); and ii) fossil Abiotic Depletion Potentials (fADP). The mature water electrolysis was used for benchmarking in order to elucidate the target performance in which PEC technology could be positively implemented at large-scale. Efficiencies over 10% (STH) and 7 years of lifetime are compulsory in the coming developments to achieve a positive scaling-up.

The abundant hydro resources in Nepal have resulted in the generation of electricity almost exclusively from hydropower plants. Several hydropower plants are also currently under construction. There is no doubt that the surplus electricity will be significantly high in the coming years. Given the previous trend in electricity consumption it will be a challenge to maximize the use of surplus electricity. In this work the potential solutions to maximize the use of this surplus electricity have been analysed. Three approached are proposed: (i) increasing domestic electricity consumption by shifting the other energy use sectors to electricity (ii) cross-border export of electricity and (iii) conversion of electricity to hydrogen via electrolysis. The current state of energy demand and supply patterns in the country are presented. Future monthly demand forecasts and surplus electricity projections have been made. The hydrogen that can be produced with the surplus electricity via electrolysis is determined and an economic assessment is carried out for the produced hydrogen. The analysis of levelized cost of hydrogen (LCOH) under different scenarios resulted values ranging from 3.8 €/kg to 4.5 €/kg.

Reactor structure design plays an important role in the performance of solar-thermal methane reforming reactors. Based on a conventional preheating reactor this study proposed a cylindrical solar methane reforming reactor with multiple inlets to vary the temperature field distribution which improved the temperature of the reaction region in the reactor thereby improving the reactor performance. A multi-physical model that considers mass momentum species and energy conservation as well as thermochemical reaction kinetics of methane reforming was applied to numerically investigate the reactor performance and analyze the factors that affect performance improvement. It was found that compared with a conventional preheating reactor the proposed cylindrical reactor with inner and external inlets for gas feeding enhanced heat recovery from the exhausted gas and provided a more suitable temperature field for the reaction in the reactor. Under different operating conditions the methane conversion in the cylindrical reactor with multi-inlet increased by 9.5% to 19.1% and the hydrogen production was enhanced by 12.1% to 40.3% in comparison with the conventional design even though the total reaction catalyst volume was reduced.

The novelty of the paper is the analysis of the possibilities of reducing the operating costs of a mine water pumping station in an abandoned coal mine. To meet the energy needs of the pumping station and reduce the carbon footprint “green” energy from a photovoltaic farm was used. Surplus green energy generated during peak production is stored in the form of green hydrogen from the water electrolysis process. Rainwater and process water are still underutilized sources for increasing water resources and reducing water stress in the European Union. The article presents the possibilities of using these waters after purification in the production of green hydrogen by electrolysis. The article also presents three variants that ensure the energy self-sufficiency of the proposed concepts of operation of the pumping station.

Offshore wind power stands out as a promising renewable energy source offering substantial potential for achieving low carbon emissions and enhancing energy security. Despite its potential the expansion of offshore wind power faces considerable constraints in offshore power transmission. Hydrogen production derived from offshore wind power emerges as an efficient solution to overcome these limitations and effectively transport energy. This study systematically devises diverse hydrogen energy supply chains tailored to the demands of the transportation and chemical industries meticulously assessing the levelized cost of hydrogen (LCOH). Our findings reveal that the most cost-efficient means of transporting hydrogen to the mainland is through pipelines particularly when the baseline distance is 50 km and the baseline electricity price is 0.05 USD/kWh. Notably delivering hydrogen directly to the port via pipelines for chemical industries proves considerably more economical than distributing it to hydrogen refueling stations with a minimal cost of 3.6 USD/kg. Additionally we assessed the levelized cost of hydrogen (LCOH) for supply chains that transmit electricity to ports via submarine cables before hydrogen production and subsequent distribution to chemical plants. In comparison to offshore hydrogen production routes these routes exhibit higher costs and reduced competitiveness. Finally a sensitivity analysis was undertaken to scrutinize the impact of delivery distance and electricity prices on LCOH. The outcomes underscore the acute sensitivity of LCOH to power prices highlighting the potential for substantial reductions in hydrogen prices through concerted efforts to lower electricity costs.

This work presents the design and application of two control techniques—a model predictive control (MPC) and a proportional integral derivative control (PID) both in combination with a multilayer perceptron neural network—to produce hydrogen gas on-demand in order to use it as an additive in a spark ignition internal combustion engine. For the design of the controllers a control-oriented model identified with the Hammerstein technique was used. For the implementation of both controllers only 1% of the overall air entering through the throttle valve reacted with hydrogen gas allowing maintenance of the hydrogen–air stoichiometric ratio at 34.3 and the air–gasoline ratio at 14.6. Experimental results showed that the average settling time of the MPC controller was 1 s faster than the settling time of the PID controller. Additionally MPC presented better reference tracking error rates and standard deviation of 1.03 × 10−7 and 1.06 × 10−14 and had a greater insensitivity to measurement noise resulting in greater robustness to disturbances. Finally with the use of hydrogen as an additive to gasoline there was an improvement in thermal and combustion efficiency of 4% and 0.6% respectively and an increase in power of 545 W translating into a reduction of fossil fuel use.

The main purpose of this article is to provide a short review of proton exchange membrane electrolyzer (PEMEL) modeling used for power electronics control. So far three types of PEMEL modeling have been adopted in the literature: resistive load static load (including an equivalent resistance series-connected with a DC voltage generator representing the reversible voltage) and dynamic load (taking into consideration the dynamics both at the anode and the cathode). The modeling of the load is crucial for control purposes since it may have an impact on the performance of the system. This article aims at providing essential information and comparing the different load modeling.

In recent years with the development of hydrogen energy economy there is an increasing demand for hydrogen in the market and hydrogen production through biomass will provide an important way to supply clean environmentally friendly and highly efficient hydrogen. In this study cow dung was selected as the biomass source and the efficiency of the biomass to hydrogen reaction was explored by coupling high temperature pyrolysis and water vapor gasification. The experimental conditions of gasification temperature water mass fraction heating rate and feed temperature were systematically studied and optimized to determine the optimal conditions for in situ hydrogen production by gasification of cow dung. The relationship of each factor to the yield of hydrogen production by gasification of cow dung semi-coke was investigated in order to elucidate the mechanism of the hydrogen production. The experiment determined the optimal operating parameters of in situ gasification: gasification temperature 1173 K water mass fraction 80% heating rate 10 K/min and feed temperature 673 K. The semi-coke treatment separated high temperature pyrolysis and water vapor gasification and reduced the influence on gasification of volatile substances such as tar extracted from pyrolysis. The increase of semi-coke preparation temperature increases the content of coke reduces the volatile matter and improves the yield of hydrogen; the small size of semi-coke particles and large specific surface area are beneficial to the gasification reaction.