Production & Supply Chain

Electrolytic hydrogen from renewable sources is central to many nations' net-zero emission strategies serving as a low-carbon alternative for traditional uses and enabling decarbonisation across multiple sectors. Current stringent policies in the EU and US are set to soon require hourly time-matching of renewable electricity generation used by electrolysers aimed at ensuring that hydrogen production does not cause significant direct or indirect emissions. Whilst such requirements enhance the “green credentials” of hydrogen they also increase its production costs. A modest relaxation of these requirements offers a practicable route for scaling up low-carbon hydrogen production optimising both costs and emission reductions. Moreover in jurisdictions with credible and near-to-medium-term decarbonisation targets immediate production of electrolytic hydrogen utilising grid electricity would have a lifetime carbon intensity comparable to or even below blue hydrogen and very significantly less than that of diesel emphasising the need to prioritise rapid grid decarbonisation of the broader grid.

Biohydrogen a low-carbon footprint technology can play a significant role in decarbonizing the energy system. It uses existing infrastructure is easily transportable and produces no greenhouse gas emissions. Four technologies can be used to produce biohydrogen: photosynthetic biohydrogen dark fermentation (DF) photo-fermentation and microbial electrolysis cells (MECs). DF produces more biohydrogen and is flexible with organic substrates making it a sustainable method of waste repurposing. However low achievable biohydrogen yields are a common issue. To overcome this catalytic mechanisms including enzymatic systems such as [Fe-Fe]- and [Ni-Fe]-hydrogenases in DF and electroactive microbial consortia in MECs alongside advanced electrode catalysts which collectively surmount thermodynamic and kinetic constraints and the two stage system such as DF connection to photo-fermentation and anaerobic digestion (AD) to microbial electrolysis cells (MECs) have been investigated. MECs can generate biohydrogen at better yields by using sugars or organic acids and combining DF and MEC technologies could improve biohydrogen production. As such this review highlights the challenges and possible solutions for coupling DF–MEC while also offering knowledge regarding the technical and microbiological aspects.

The article discusses a regenerative heat exchange system for a solid oxide electrolyzer cell (SOEC) used in the production of green hydrogen. The heating system comprises four heat exchangers one condenser heat exchanger and a mixer evaporator. A pump and two throttle valves have been added to separate the hydrogen at an elevated steam condensation temperature. Assuming steady flow a thermodynamic analysis was performed to validate the design and to predict the main parameters of the heating system. Numerical optimization was then used to determine the optimal temperature distribution ensuring the lowest possible additional external energy requirement for the regenerative system. The proportions of energy gained through heat exchange were determined and their distribution analyzed. The calculated thermal efficiency of the regenerative system is 75% while its exergy efficiency is 73%. These results can be applied to optimize the design of heat exchangers for hydrogen production systems using SOECs.

Hydrogen is a key energy carrier for decarbonizing multiple sectors particularly when produced via water electrolysis powered by renewable energy. Proton exchange membrane (PEM) electrolyzers are well suited for this application due to their ability to rapidly adjust to fluctuating power inputs. Despite being conventionally operated at high temperatures and pressures to reduce heating and compression needs recent studies suggest that under partial loads lower operating conditions may enhance efficiency. This study introduces a novel optimization framework for dynamically adjusting pressure and temperature in PEM electrolyzers. The model integrates an efficiency map within a Mixed-Integer Linear Programming (MILP) formulation and applies McCormick tightening to address nonlinearities. A one-week case study demonstrates operational cost reductions of up to 12.5 % through optimal control favoring lower temperatures and pressures at low current densities and higher temperatures near rated load while maintaining moderate pressures. The results show improved efficiency and reduced hydrogen crossover enhancing safety and enabling scalable application over extended time horizons. These insights are valuable for long-term planning and evaluation of hydrogen production and storage systems.

This study evaluates the feasibility of repurposing produced water—an abundant byproduct of hydrocarbon extraction—for green hydrogen production in Wyoming USA. Analysis of geospatial distribution and production volumes reveals that there are over 1 billion barrels of produced water annually from key basins with a general total of dissolved solids (TDS) ranging from 35000 to 150000 ppm though Wyoming’s sources are often at the lower end of this spectrum. Optimal locations for hydrogen production hubs have been identified particularly in high-yield areas like the Powder River Basin where the top 2% of fields contribute over 80% of the state’s produced water. Detailed water-quality analysis indicates that virtually all of the examined sources exceed direct electrolyzer feed requirements (e.g. 10% LCOH) are notable electricity pricing (50–70% LCOH) and electrolyzer CAPEX (20–40% LCOH) are dominant cost factors. While leveraging produced water could reduce freshwater consumption and enhance hydrogen production sustainability further research is required to optimize treatment processes and assess economic viability under real-world conditions. This study emphasizes the need for integrated approaches combining water treatment renewable energy and policy incentives to advance a circular economy model for hydrogen production.

This research models a 20 MW PEM hydrogen plant. PEM units operate in the 60 to 80 ◦C range based on their location and size. This study aims to recover the waste heat from PEM modules to enhance the efficiency of the plant. In order to recover the heat two systems are implemented: (a) recovering the waste heat from each PEM module; (b) recovering the heat from hot water to produce electricity utilizing an organic refrigerant cycle (ORC). The model is made by ASPEN® V14. After modeling the plant and utilizing the ORC the module is optimized using Python to maximize the electricity produced by the turbine therefore enhancing the efficiency. The system is a closed-loop cycle operating at 25 ◦C and ambient pressure. The 20 MW PEM electrolyzer plant produces 363 kg/hr of hydrogen and 2877 kg/hr of oxygen. Based on the higher heating value of hydrogen the plant produces 14302.2 kWh of hydrogen energy equivalents. The ORC is maximized by increasing the electricity output from the turbine and reducing the pump work while maintaining energy conservation and mass balance. The results show that the electricity power output reaches 555.88 kW and the pump power reaches 23.47 kW.

In an effort to bridge the gap between academic research and industrial application this study investigates the integration potential of steam methane reforming and Co-electrolysis for the efficient conversion of refinery offgases into high-purity syngas. Experimental work was conducted under conditions representative of industrial environments using platinum- and nickel-based catalysts in steam reforming to assess methane conversion and H2 /CO ratio at varying temperatures and gas hourly space velocities (GHSV). Co-electrolysis was evaluated in solid oxide electrolysis cells (SOECs) across a range of gas compositions (H2O/CO2 /H2 /CO) including pure CO2 electrolysis as a strategy for pre-electrolysis hydrogen removal. Electrochemical performance was analyzed using impedance spectroscopy distribution of relaxation times (DRT) and current–voltage characterization. Results confirm the superior stability and performance of the Pt catalyst under high-throughput conditions while Ni-based systems were more sensitive to operational fluctuations. In the SOEC increased H2O content accelerated reaction kinetics whereas CO2 concentration governed polarization resistance. To enable optimal SOEC operation the addition of steam downstream of the reformer is proposed as a means of adjusting the reformate composition. The findings demonstrate that tuning reforming and electrolysis conditions in tandem offers a promising route for sustainable syngas production using renewable electricity. This work establishes a foundation for further development of integrated thermo-electrochemical systems tailored to industrial gas streams.

In this study the electrolysis of water by using ammonium chloride (NH4Cl) as an electrolyte was investigated for the production of hydrogen gas. The assembled electrochemical cell consists mainly of twenty-one stainless-steel electrodes and a direct current from a battery ammonium chloride solution. In the electrolysis process hydrogen and oxygen are developed at the same time and collected as a mixture to be used as a fuel. This study explores a technic regarding the matching of oxyhydrogen (HHO) electrolyzers with photovoltaic (PV) systems to make HHO gas. The primary objective of the present research is to enable the electrolyzer to operate independently of other energy origins functioning as a complete unit powered solely by PV. Moreover the impact of using PWM on cell operation was investigated. The experimental data was collected at various time intervals NH4Cl concentrations. Additionally the hydrogen unit consists of two cells with a shared positive pole fixed between them. Some undesirable anodic reaction affects the efficiency of hydrogen gas production because of the corrosion of anode to ferrous hydroxide (Fe(OH)2). Polyphosphate Inhibitor was used to minimize the corrosion reaction of anode and keep the efficiency of hydrogen gas flow. The optimal concentration of 3M for ammonium chloride was identified balancing a gas flow rate of 772 ml/min with minimal anode corrosion. Without PWM conversion efficiency ranges between 93% and 96%. Therefore PWM increased conversion efficiency by approximately 5% leading to a corresponding increase in hydrogen gas production.

Industrial alkaline water electrolysis systems face challenges in maintaining hydrogenin-oxygen impurity within safe limits under fluctuating operating conditions. This study aims to characterize the dynamic response of hydrogen-in-oxygen concentration in an industrial 10 kW alkaline water electrolysis test platform (2 Nm3/h hydrogen output at 1.6 MPa and 90 ◦C) and to identify how operating parameters influence hydrogen-inoxygen behavior. We systematically varied the cell current system pressure and electrolyte flow rate while monitoring real-time hydrogen-in-oxygen levels. The results show that hydrogen-in-oxygen exhibits significant inertia and delay: during startup hydrogen-inoxygen remained below the 2% safety threshold and stabilized at 0.9% at full load whereas a step decrease to 60% load caused hydrogen-in-oxygen to rise to 1.6%. Furthermore reducing the pressure from 1.4 to 1.0 MPa lowered the hydrogen-in-oxygen concentration by up to 15% and halving the alkaline flow rate suppressed hydrogen-in-oxygen by over 20% compared to constant conditions. These findings provide new quantitative insights into hydrogen-in-oxygen dynamics and offer a basis for optimizing control strategies to keep gas purity within safe limits in industrial-scale alkaline water electrolysis systems.

The coupling of renewable energy sources with electrolyzers under standalone conditions significantly enhances the operational efficiency and improves the costeffectiveness of electrolyzers as a technologically viable and sustainable solution for green hydrogen production. To address the configuration optimization challenge in hybrid electrolyzer systems integrating alkaline water electrolysis (AWE) and proton exchange membrane electrolysis (PEME) this study proposes an innovative methodology leveraging the morphological analysis of Pareto frontiers to determine the optimal solutions under multi-objective functions including the hydrogen production cost and efficiency. Then the complementary advantages of AWE and PEME are explored. The proposed methodology demonstrated significant performance improvements compared with the single-objective optimization function. When contrasted with the economic optimization function the hybrid system achieved a 1.00% reduction in hydrogen production costs while enhancing the utilization efficiency by 21.71%. Conversely relative to the efficiency-focused optimization function the proposed method maintained a marginal 5.22% reduction in utilization efficiency while achieving a 6.46% improvement in economic performance. These comparative results empirically validate that the proposed hybrid electrolyzer configuration through the implementation of the novel optimization framework successfully establishes an optimal balance between the economy and efficiency of hydrogen production. Additionally a discussion on the key factors affecting the rated power and mixing ratio of the hybrid electrolyzer in this research topic is provided.

Hydrogen production via water electrolysis and renewable electricity is expected to play a pivotal role as an energy carrier in the energy transition. This fuel emerges as the most environmentally sustainable energy vector for non-electric applications and is devoid of CO2 emissions. However an electrolyzer´s infrastructure relies on scarce and energyintensive metals such as platinum palladium iridium (PGM) silicon rare earth elements and silver. Under this context this paper explores the exergy cost i.e. the exergy destroyed to obtain one kW of hydrogen. We disaggregated it into non-renewable and renewable contributions to assess its renewability. We analyzed four types of electrolyzers alkaline water electrolysis (AWE) proton exchange membrane (PEM) solid oxide electrolysis cells (SOEC) and anion exchange membrane (AEM) in several exergy cost electricity scenarios based on different technologies namely hydro (HYD) wind (WIND) and solar photovoltaic (PV) as well as the different International Energy Agency projections up to 2050. Electricity sources account for the largest share of the exergy cost. Between 2025 and 2050 for each kW of hydrogen generated between 1.38 and 1.22 kW will be required for the SOEC-hydro combination while between 2.9 and 1.4 kW will be required for the PV-PEM combination. A Grassmann diagram describes how non-renewable and renewable exergy costs are split up between all processes. Although the hybridization between renewables and the electricity grid allows for stable hydrogen production there are higher non-renewable exergy costs from fossil fuel contributions to the grid. This paper highlights the importance of nonrenewable exergy cost in infrastructure which is required for hydrogen production via electrolysis and the necessity for cleaner production methods and material recycling to increase the renewability of this crucial fuel in the energy transition.

As a result of international agreements on the reduction of CO2 emissions new technologies using hydrogen are being developed. Hydrogen despite being the most abundant element in Nature cannot be found in its pure state. Water is one of the most abundant sources of hydrogen on the planet. The proposal here is to use energy from the sea in order to obtain hydrogen from water. If plants to obtain hydrogen were to be placed in the ocean the impact of long submarines piping to the coast will be reduced. Further this will open the way for the development of ships propelled by hydrogen. This paper discusses the feasibility of an offshore installation to obtain hydrogen from the sea using ocean wave energy.

Today hydrogen (H2) is overwhelmingly produced through steam methane reforming (SMR) of natural gas which emits about 12 kg of carbon dioxide (CO2) for 1 kg of H2 (∼12 kg-CO2/kg-H2). Water electrolysis offers an alternative for H2 production but today’s electrolyzers consume over 55 kWh of electricity for 1 kg of H2 (>55 kWh/kg-H2). Electric grid-powered water electrolysis would emit less CO2 than the SMR process when the carbon intensity for grid power falls below 0.22 kg-CO2/kWh. Solar- and wind-powered electrolytic H2 production promises over 80% CO2 reduction over the SMR process but large-scale (megawatt to gigawatt) direct solar- or wind-powered water electrolysis has yet to be demonstrated. In this paper several approaches for solar-powered electrolysis are analyzed: (1) coupling a photovoltaic (PV) array with an electrolyzer through alternating current; (2) direct-current (DC) to DC coupling; and (3) direct DC-DC coupling without a power converter. Co-locating a solar or wind farm with an electrolyzer provides a lower power loss and a lower upfront system cost than long-distance power transmission. A load-matching PV system for water electrolysis enables a 10%–50% lower levelized cost of electricity than the other systems and excellent scalability from a few kilowatts to a gigawatt. The concept of maximum current point tracking is introduced in place of maximum power point tracking to maximize the H2 output by solarpowered electrolysis.

This study investigates the potential for establishing a self-sufficient renewable hydrogen production facility utilising a floating photovoltaic (FPV) system on an artificial irrigation reservoir located in a small municipality in southern Italy. The analysis examines the impact of different system configurations and operating conditions on the technical economic and environmental performance with a particular focus on hydrogen production and water conservation resulting from reduced evaporation. Different sizes of the FPV plant are considered with and without a tracking system. The electrolyser performance is evaluated under both fixed and variable load conditions also considering the integration of battery storage to ensure consistent operation. The findings indicate that the adoption of the largest FPV plant can result in the conservation of approximately 1.87 million m3 of water annually while simultaneously producing up to 4199 tons of hydrogen per year in variable load mode—more than twice the output compared to fixed load conditions. Although battery integration increases hydrogen production it also leads to higher investment and maintenance costs. Therefore the variable load operation emerges as the most economically viable option reducing the levelized cost of hydrogen (LCOH) to €13.18/kg a 26 % reduction compared to fixed load operation. Moreover the implementation of a vertical axis tracking system leads to only marginal LCOH reductions (maximum 2.2 %) and does not justify the additional complexity. In all tested scenarios the system proves to be self-sustaining. Given the case study’s location in southern Italy—where a pilot project for fuel cell–battery hybrid trains is underway—the hydrogen produced is assumed to be used for railway applications as a possible offtaker. The analysis shows that the potential of the system in terms of hydrogen production is much higher (tens of times) than the estimated demand of the present hydrogen railway configuration thus suggesting that a significant expansion of the number of trains and routes served could be considered. Although this work is based on a specific case study its key findings are potentially replicable in other contexts—particularly in Mediterranean or semi-arid regions where water scarcity may otherwise act as a limiting factor for the deployment of hydrogen production systems.

The applications and need for large-scale long-duration electrical energy storage are growing as both the share of renewable energy in energy systems and the demand for flexibility increase. One potential application is the renewable hydrogen industry where temporal matching of renewable electricity generation and hydrogen production will be required in the future according to the new European Union regulations. In this paper a case study of electrical energy storage utilization in hydrogen production is conducted in the Nordic context with a high share of wind production. The storage is used in the hydrogen production process for temporal matching. The levelized cost of storage of three medium- to long-term storage technologies is assessed using an Excel-based model with four case approaches. In the first case approach the electrolyzer load is inflexible while the other approaches explore how the flexibility of the electrolyzer and the increase in renewable production capacity affect the size and cost of the storage. Electro-thermal energy storage based on sand as storage material presented the lowest levelized cost of storage (114-198 €/MWh) due to its low energy-related investment cost. However the results show that additional usage purposes for all examined storage technologies are required to avoid high investment costs. Additionally flexibility from the electrolyzer load and over-investing in renewable capacity is required. In conclusion storage should not be the only component providing flexibility in the studied system and it should be used to integrate multiple assets in the wider energy system to reach cost-effectiveness. This paper brings novelty by expanding on the storage technology options considered in previous literature and deepening the perspective of storage as a component in renewable hydrogen production. Future research should assess the effect of electricity prices and emissions allowance prices from the regulatory perspective which could further reduce the storage investment.

Hydrogen will be an integral component for the transition to sustainable energy generation and storage due to its favourable characteristics and versatility in its application. This research provides a greater understanding of the potential light energy has to increase water electrolysis efficiency by examining the effects that light energy fields have on the molecular and electrochemical dynamics during electrolysis. The results indicate that light energy increased efficiency by ~10% while enhancing the molecular dynamics regardless of application. The application of a line laser generated the highest gains in efficiency with a maximum of ~15%. Furthermore the application of a line laser with a linear magnetic field resulted in a synergistic effect which generated higher increases in molecular dynamics as well as an ~18% increase in efficiency and a ~58% increase in hydrogen gas production. As such the application of light energy fields presents a promising method for enhancing water’s molecular dynamics and electrolysis efficiency.

The deployment of large installed power capacities from intermittent renewable energy sources requires balancing to ensure the steady and safe operation of the electrical grid. New methods of energy storage are essential to store excess electrical power when energy is not needed and later use it during high-demand periods both in the short and long term. Power-to-Gas (P2G) is an energy storage solution that uses electric power produced from renewables to generate gas fuels such as hydrogen which can be stored for later use. Hydrogen produced in this manner can be utilized in energy storage systems and in transportation as fuel for cars trams trains or buses. Currently most hydrogen is produced from fossil fuels. Solid-oxide electrolysis (SOE) offers a method to produce clean hydrogen without harmful emissions being the most efficient of all electrolysis methods. The objective of this work is to determine the optimal operational parameters of an SOE system such as lower heating value (LHV)-based efficiency and total input power based on calculations from a mathematical model. The results are provided for three different operating temperature levels and four different steam utilization ratios. The introductory chapter outlines the motivation and background of this work. The second chapter explains the basics of electrolysis and describes its different types. The third chapter focuses on solid-oxide electrolysis and electrolyzer systems. The fourth chapter details the methodology including the mathematical formulations and software used for simulations. The fifth chapter presents the results of the calculations with conclusions. The final chapter summarizes this work.

The production of green hydrogen the cleanest energy source plays a crucial role in enhancing the efficiency of renewable energy systems by utilizing surplus energy that would otherwise be wasted. With the global shift towards sustainability and the rising adoption of renewable energy sources green hydrogen is gaining significant importance as both an energy carrier and a storage solution. However determining the optimal locations for green hydrogen production facilities remains a complex challenge due to the interplay of technical economic logistical and environmental factors. This study introduces the City Location Evaluation Optimization for Green Hydrogen (CELO_GH) algorithm a novel heuristic approach designed to address this challenge. Unlike conventional multi-criteria decision-making (MCDM) models CELO_GH dynamically evaluates cities by considering renewable energy surplus proximity to industrial hydrogen demand port and pipeline accessibility and economic viability. A case study conducted in Turkey demonstrates the effectiveness of the approach by identifying optimal cities for green hydrogen production based on real-world energy and infrastructure data. The problem was also solved with the genetic algorithm and the results were compared and it was seen that the proposed heuristic provides the lowest cost location selection. A geographically flexible methodology as the proposed algorithm can be applied globally to regions with high renewable energy potential ensuring scalability and adaptability for future energy transition strategies. The results provide valuable insights for policy-makers energy investors and industrial planners aiming to optimize green hydrogen infrastructure while ensuring cost efficiency and sustainability.

This review paper presents an overview of fuel cell electrochemical systems that can be used for clean large-scale power generation and energy storage as global energy concerns regarding emissions and greenhouse gases escalate. The fundamental thermochemical and operational principles of fuel cell power generation and electrolyzer technologies are discussed with a focus on high-temperature solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs) that are best suited for grid scale energy generation. SOFCs and SOECs share similar promising characteristics and have the potential to revolutionize energy conversion and storage due to improved energy efficiency and reduced carbon emissions. Electrochemical and thermodynamic foundations are presented while exploring energy conversion mechanisms electric parameters and efficiency in comparison with conventional power generation systems. Methods of converting hydrocarbon fuels to chemicals that can serve as fuel cell fuels are also presented. Key fuel cell challenges are also discussed including degradation thermal cycling and long-term stability. The latest advancements including in materials selection research design and manufacturing methods are also presented as they are essential for unlocking the full potential of these technologies and achieving a sustainable near zero-emission energy future.

It is believed that hydrogen will play an essential role in energy transition and achieving the net-zero target by 2050. Currently global hydrogen production mostly relies on processing fossil fuels such as coal and natural gas commonly referred to as grey hydrogen production while releasing substantial amounts of carbon dioxide (CO2). Developing economically and technologically viable pathways for hydrogen production while eliminating CO2 emissions becomes paramount. In this critical review we examine the common grey hydrogen production techniques by analyzing their technical characteristics production efficiency and costs. We further analyze the integration of carbon capture utilization and storage (CCUS) technology establishing the zero-carbon strategy transiting from grey to blue hydrogen production with CO2 capture and either utilized or permanently stored. Today grey hydrogen production exhibits technological diversities with various commercial maturities. Most methods rely on the effectiveness of catalysts necessitating a solution to address catalyst fouling and sintering in practice. Although CCUS captures utilizes or stores CO2 during grey hydrogen production its wide application faces multiple challenges regarding the technological complexity cost and environmental benefits. It is urgent to develop technologically mature low-cost and low-energy-consumption CCUS technology implementing extensive large-scale integrated pilot projects.

The study presents the development of a novel integrated wind-biomass energy system designed for sustainable urban development leveraging municipality waste and wind power energy sources. This innovative system is capable of producing multiple forms of energy including electricity cooling heat and hydrogen addressing the diverse energy needs of urban communities. It integrates advanced thermodynamic cycles like Kalina and water electrolysis via an alkaline electrolyzer. In addition the system uniquely combines power and refrigeration while utilizing landfills as an energy source. The designed system is thermodynamically modeled using the Engineering Equation Solver and process wise simulated by the Aspen Plus software to ensure better performance. By integrating advanced thermodynamic cycles such as the Kalina and combined power and refrigeration system the overall system is designed to maximize the utilization of biomass energy content and enhances overall performance. The thermodynamic analysis results reveal that the system achieved remarkable results with an energy efficiency of 67.60% and an exergy efficiency of 59.7% demonstrating its tangible performance compared to other standalone energy systems. The refrigeration system itself achieves an energetic COP of 5.41 and an exergetic COP of 1.7. Additionally the system's hydrogen production facilitated by an alkaline electrolyzer reaches a rate of 5.38 kg/h highlighting its potential to contribute to clean hydrogen energy solutions. Moreover the exergo-environmental assessment shows that the system is environmentally friendly. The cost assessment shows that the system reaches profitability in 7 years and demonstrates growth achieving a substantial NPV of 192.39 million by 30 years highlighting its long-term financial viability.

The transition to a hydrogen-based economy presents a promising solution to the challenges posed by unsus tainable energy systems and reliance on fossil fuels. This comprehensive review explores various hydrogen production methods emphasizing their technological advancements sustainability implications and future prospects. Beginning with an overview of hydrogen’s significance as a clean energy carrier the review examines key production methods such as Steam Methane Reforming Electrolysis (Proton Exchange Membrane alkaline solid oxide) Biomass Gasification Photoelectrochemical Water Splitting and Thermochemical Processes. Each method is scrutinized for its efficiency environmental impact and scalability providing valuable insights into their roles in advancing the hydrogen economy. The review highlights the transformative potential of hydrogen production to replace fossil fuels due to its ability to store renewable energy long-term and its zero emissions. It also discusses potential technological advancements including high-efficiency solid-state electrolysis and advanced catalysts for water splitting highlighting avenues for innovation in hydrogen production. Additionally policy recommendations aimed at promoting the hydrogen economy and fostering collaboration between academia industry and governments are elucidated. Through a detailed analysis of hydrogen production technologies and future prospects this review contributes to shaping the trajectory of sustainable energy sys tems advancing the adoption of hydrogen as a key energy vector and underscoring the importance of alternative and sustainable energy sources.

Alternative fuel opportunities can satisfy energy security and reduce carbon emissions. In this regard the hydrogen fuel is derived from the source of environmental pollutants like sewage and algae wastewater through hydrothermal gasification technique using a KOH catalyst with varied gasification process parameters of duration and temperature of 6–30 min and 500-800 ◦C. The novelty of the work is to identify the optimum gasification process parameter for obtaining the maximum hydrogen yield using a KOH catalyst as an alternative fuel for agricultural engine applications. Influences of gasification processing time and temperature on H2 selectivity Carbon gasification efficiency (CE) Lower heating value (LHV) Hydrogen yield potential (HYP) and gasification efficiency (GE) were studied. Its results showed that the gasifier operated at 800 ◦C for 30 min offering maximum hydrogen yield (26 mol/kg) and gasification efficiency (58 %). The synthesized H2 was an alternative fuel blended with diesel fuel/TiO2 nanoparticles. It was experimentally studied using an internal combustion engine. Influences of H2 on engine perfor mance like brake-specific fuel consumption brake thermal efficiency and emission performances were measured and compared with diesel fuel. The results showed that DH20T has the least (420g/kWh) brake-specific fuel consumption (BSFC) and superior brake thermal efficiency of about 25.2 %. The emission results revealed that the DH20T blend showed the NOX value increased by almost 10.97 % compared to diesel fuel whereas the CO UHC and smoke values reduced by roughly 31.25 28.34 and 42.35 %. The optimum fuel blend (DH20T) result is rec ommended for agricultural engine applications.

Conventional hydrogen production processes which often involve fossil raw materials emit significant amounts of carbon dioxide into the atmosphere. This study critically evaluates the feasibility of using sugarcane biomass as an energy source to produce green hydrogen. In the 2023/2024 harvest Brazil the world’s largest sugarcane producer processed approximately 713.2 million metric tons of sugarcane. This yielded 45.68 million metric tons of sugar and 29.69 billion liters of first-generation ethanol equivalent to approximately 0.0416 liters of ethanol per kilogram of sugarcane. A systematic literature review was conducted using Scopus and Clarivate Analytics Web of Science resulting in the assessment of 335 articles. The study has identified seven potential biohydrogen production methods including two direct approaches from second-generation ethanol and five from integrated bioenergy systems. Experimental data indicate that second-generation ethanol can yield 594 MJ per metric ton of biomass with additional energy recovery from lignin combustion (1705 MJ per metric ton). Moreover advances in electrocatalytic reforming and plasma-driven hydrogen production have demonstrated high conversion efficiencies addressing key technical barriers. The results highlight Brazil’s strategic potential to integrate biohydrogen production within its existing bioenergy infrastructure. By leveraging sugarcane biomass for green hydrogen the country can contribute significantly to the global transition to sustainable energy while enhancing its energy security.

The article provides a short review on catalyst-based processes for the production of hydrogen starting from methane both of fossil origin and from sustainable processes. The three main paths of steam- and dry-reforming partial oxidation and thermo-catalytic decomposition are briefly introduced and compared above all with reference to the latest publications available and to new catalysts which obey the criteria of lower environmental impact and minimize the content of critical raw materials. The novel strategies based on chemical looping with CO2 utilization membrane separation electrical-assisted (plasma and microwave) processes multistage reactors and catalyst patterning are also illustrated as the most promising perspective for CH4 reforming especially on small and medium scale. Although these strategies should only be considered at a limited level of technological readiness research on these topics including catalyst development and process optimization represents the crucial challenge for the scientific community