Publications

The biological production of hydrogen offers a renewable and potentially sustainable alternative for clean energy generation. In Northeast Brazil depleted oil reservoirs (DORs) present a unique opportunity to integrate biotechnology with existing fossil fuel infrastructure. These subsurface formations rich in residual hydrocarbons (RH) and native H2 producing microbiota can be repurposed as bioreactors for hydrogen production. This process often referred to as “Gold Hydrogen” involves the in situ microbial conversion of RH into H2 typically via dark fermentation and is distinct from green blue or grey hydrogen due to its reliance on indigenous subsurface biota and RH. Strategies include nutrient modulation and chemical additives to stimulate native hydrogenogenic genera (Clostridium Petrotoga Thermotoga) or the injection of improved inocula. While this approach has potential environmental benefits such as integrated CO2 sequestration and minimized surface disturbance it also presents risks namely the production of CO2 and H2S and fracturing which require strict monitoring and mitigation. Although infrastructure reuse reduces capital expenditures achieving economic viability depends on overcoming significant technical operational and biotechnological challenges. If widely applied this model could help decarbonize the energy sector repurpose legacy infrastructure and support the global transition toward low-carbon technologies.

Renewable hydrogen production is a pivotal technology in transitioning to sustainable energy and is essential for global decarbonisation efforts. This study explores the integration of hydrogen production into sugarcane bio refineries which have shifted from traditional sugar production to integrated bioenergy hubs. Specifically steam reforming of ethanol was selected as the process for hydrogen generation. A comprehensive techno-economic analysis was developed to address research gaps and guide future work. A scenario of hydrogen production coupled with carbon capture was analysed illustrating the potential to reduce the carbon footprint and utilise carbon dioxide for producing chemicals. The minimum selling price for hydrogen was determined to be 4.6 US $/kg for the base case scenario and 4.9 US$/kg for the comparison scenario with carbon capture positioning it below the current average market price of 7.2 US$/kg. The capital and operating expenditures were determined to be US$ 273.1 million and 157.8 million for a 42400 t/y hydrogen plant and integrating carbon capture considering 282800 t/y of carbon co-product yield was calculated at US$ 344.1 million and US$ 167.8 million respectively. This dual approach of hydrogen production and carbon capture presents a strategy for imple menting low-carbon processes that future biorefineries may consider. The primary impact highlighted by this integration is the enhancement of the sugarcane biorefineries’ value proposition leveraging undervalued energy sources such as electricity and biogas. This study underscores the economic and environmental benefits of incorporating hydrogen production into sugarcane biorefineries on a large scale offering a framework for future research and technological development.

The integration of renewable energy sources such as wind and solar power at high proportions has become an inevitable trend in the development of power systems under the new power system framework. The construction of a microgrid system incorporating hydrogen energy storage and battery energy storage can leverage the complementary advantages of long-term and short-term hybrid storage achieving power and energy balance across multiple time scales in the power system. To prevent frequent startstop cycles of hydrogen storage devices and lithium battery storage under overcharge and overdischarge conditions a coordinated control strategy for power distribution in a microgrid with hydrogen storage is proposed. First a fuzzy control algorithm is used for power distribution between hydrogen storage and lithium battery storage. Then the hydrogen storage tank’s state of health (SOH) and the lithium battery’s state of charge (SOC) are compared with the goal of selecting a multi-stack fuel cell system operating at its optimal efficiency point where each fuel cell stack outputs 10 kW. This further ensures that the SOC and SOH remain within reasonable ranges. Finally simulations are conducted in MATLAB/Simulink R2018b to verify that the proposed strategy maintains stability in the DC bus and alleviates issues of overcharge and overdischarge ensuring that both the system’s SOC and SOH remain within a reasonable range thereby enhancing equipment lifespan and system stability

Hydrogen as an energy carrier will play an important role in the future in achieving sustainable development goals in the energy and mobility sectors as well as to reach decarbonization goals. Currently adopted hydrogen strategies foresee a significant increase in the amount of hydrogen used in the future. To meet this increased volume in the most sustainable way a careful analysis of potential hydrogen production technologies is necessary considering real environmental impacts. This paper provides a comprehensive overview of different non-renewable and renewable hydrogen production technologies and evaluates their environmental effects based on global warming potential (GWP). Environmental footprint data discussed in this paper are based on published life-cycle assessment (LCA) results. As direct comparison of LCA results is difficult due to different LCA scenarios selected system boundaries various material components and manufacturing techniques a novel multidimensional comparison approach was developed to understand LCA results better and to give a more comprehensive picture of environmental footprint components. In addition to methodological issues the key influencing factors of the carbon footprint of different hydrogen production technologies were also identified. It is not possible to identify one stand-alone technology that would be the most environmentally friendly in all circumstances it is essential to investigate all the technologies in the given context of use. Regarding watersplitting it is outstandingly crucial to examine the source of the electricity because it strongly influences the GWP of this H2 production technology. If the GWP of the electricity is high this technology could be more harmful to the environment than the steam methane reforming (SMR).

Photocatalysis emerged as a promising alternative to address fossil fuel scarcity and the limitations of other clean energy sources. Photocatalysis enables hydrogen production via water splitting using photocatalysts and light irradiation which can be stored and utilized across various applications. Photocatalysis has exhibited significant improvements and promising yields in hydrogen production surpassing its initial stages. The current photocatalyst market offers diverse materials with unique characteristics and continuous evolution is observed in their synthesis methods. This contribution aims to compile recent literature on advancements in photocatalysts for hydrogen production with particular emphasis on photocatalyst type hydrogen production performance and market trends.

The marine industry must reduce emissions to comply with recent and future regulations. Solid oxide fuel cells (SOFCs) are seenas a promising option for efficient power generation on ships with reduced emissions. However it is unclear how the devices canbe integrated and how this affects the operation of the ship economically and environmentally. This paper reviews studies thatconsider SOFC for marine applications. First this article discusses noteworthy developments in SOFC systems includingpower plant options and fuel possibilities. Next it presents the design drivers for a marine power plant and explores how anSOFC system performs. Hereafter the possibilities for integrating the SOFC system with the ship are examined alsoconsidering economic and environmental impact. The review shows unexplored potential to successfully integrate SOFC withthermal and electrical systems in marine vessels. Additionally it is identified that there are still possibilities to improve marineSOFC systems for which a holistic approach is needed for design at cell stack module and system level. Nevertheless it isexpected that hybridisation is needed for a technically and economically feasible ship. Despite its high cost SOFC systemscould significantly reduce GHG NO X SO X PM and noise emissions in shipping

The safety of hydrogen-blended natural gas (HBNG) in a confined space is an issue especially for ventilation processes. In this study leakage and ventilation processes of low-pressure HBNG with different hydrogen-blended ratio (HBR) in a confined space are simulated and validated by experiment based on similarity criteria. For the leakage process the leak direction and HBR do not significantly affect gas accumulation behaviour. The required time for a gas cloud to fill space decreases slightly with HBR rising and they generally show a linear relationship. For the ventilation process the main influences on the leakage process are the total leakage mass and the ventilation conditions. The required time for hazardous gas cloud dissipation increases with total leakage mass and decreases with HBR. For different ventilation conditions the ranking of required time to exhaust leaked gas is low > centre > high > mix. Through the analysis of pressure distribution it is found time difference is produced by different airflow patterns. With the asymmetric layout outside air rushes into the confined space from the high side and then flows out from the low side carrying the leaked HBNG. These findings inform the design of ventilation for HBNG utilization scenarios like restaurant facing the street.

Renewable energy-based water electrolysis for hydrogen production is an effective pathway to achieve green energy transition. However the intermittency and randomness of renewable energy pose numerous challenges to the safe and stable operation of hydrogen production systems with the wide power fluctuation adaptability and economic efficiency of electrolyzers being prominent issues. Hybrid electrolyzers combine the operational characteristics of proton exchange membrane (PEM) and alkaline electrolyzers leveraging the advantages of both to improve adaptability to wide power fluctuations and economic efficiency thereby enhancing the overall system efficiency. To ensure coordinated operation of hybrid electrolyzers it is essential to consider their startstop characteristics and the impact of hydrogen to oxygen (HTO) concentration on the hydrogen production system. To achieve this we first discuss the operating characteristics of both types of electrolyzers and the in fluence of system parameters on HTO concentration. A control scheme for hybrid electrolyzer systems consid ering HTO content is proposed. By analyzing the electrolyzer efficiency curve the optimal efficiency point under low power operation is identified enabling the electrolyzers to operate at this optimal efficiency thus enhancing the efficiency of the hybrid electrolyzer system. The implementation of a dual-layer rotation control strategy effectively balances the lifecycle loss of the electrolyzers. Additionally reducing the pressure during startup broadens the startup range of the hybrid electrolyzer.

HyCARE project supported by the Clean Hydrogen Partnership of the European Union deals with a prototype hydrogen storage tank using a solid-state hydrogen carrier. Up to 40 kilograms of hydrogen are stored in 12 tanks at less than 50 barg and less than 100°C. The innovative design is based on a standard 20-foot container including 12 TiFe-based metal hydride (MH) hydrogen storage tanks coupled with a thermal energy storage in phase change materials (PCM). This article aims at showing the main risks related to hydrogen storage in a MH system and the safety barriers considered based on HyCARE’s specific risk analysis. Regarding the TiFe MH material used to store hydrogen experimental tests showed that the exposure of the MH to air or water did not cause spontaneous ignition. Furthermore an explosion within the solid MH cannot propagate due to internal pore size. Additionally in case of leakage the speed of hydrogen desorption from the MH is self-limited which is an important safety characteristic since it reduces the potential consequences from the hydrogen release. Regarding the integrated system the critical scenarios identified during the risk analysis were explosion due to release of hydrogen inside or outside the container internal explosion inside MH tanks due to accidental mix of hydrogen and air and asphyxiation due to inert gas accumulation in the container. The identification phase of risk analysis identified the most relevant safety barriers already in place and recommended additional ones if needed which were later implemented to further reduce the risk. The main safety barriers identified were material and component selection (including the MH selected) safety interlocks safety valves ventilation gas detection and safety distances. The risk management process based on risk identification and assessment contributed to coherently integrate inherently safe design features and safety barriers.

Maximizing the hydrogen evolution reaction (HER) remains challenging due to its nonlinear kinetics and complex charge interactions within the electric double layer (EDL). This study introduces an adaptive current density control approach using a Markov Decision Process (MDP) to enhance HER performance in alkaline water electrolysis. The MDP algorithm dynamically adjusts current release timings from three capacitors connected to the cathode based on feedback from hydrogen concentration levels. Results show that this fluctuating control strategy is more effective than static or linearly increasing methods as it helps minimize overpotential reduce heat buildup and prevent hydrogen bubble accumulation. The MDP -optimized system achieved 7460 ppm in 60 minutes outperforms the control condition (5802 ppm ) produced under uncontrolled conditions. This work highlights a novel application of reinforcement learning to actively regulate electrochemical parameters offering a promising mechanism for improving electrolyzer efficiency.

Enhancing system durability and fuel economy stands as a crucial factor in the energy management of fuel cell hybrid vehicles. This paper proposes an Equivalent Consumption Minimization Strategy (ECMS) based on the Genetic Algorithm (GA) aiming to minimize the overall operating cost of the system. First this study establishes a dynamic model of the hydrogen–electric hybrid vehicle a static input–output model of the hybrid power system and an aging model. Next a speed prediction method based on an Autoregressive Integrated Moving Average (ARIMA) model is designed. This method fits a predictive model by collecting historical speed data in real time ensuring the robustness of speed prediction. Finally based on the speed prediction results an adaptive Equivalence Factor (EF) method using a GA is proposed. This method comprehensively considers fuel consumption and the economic costs associated with the aging of the hydrogen–electric hybrid system forming a total operating cost function. The GA is then employed to dynamically search for the optimal EF within the cost function optimizing the system’s economic performance while ensuring real-time feasibility. Simulation outcomes demonstrate that the proposed energy management strategy significantly enhances both the durability and fuel economy of the fuel cell hybrid vehicle.

The integration of water electrolyzers and photovoltaic (PV) solar technology is a potential development in renewable energy systems offering new avenues for sustainable energy generation and storage. This coupling consists of using PV-generated electricity to power water electrolysis breaking down water molecules into hydrogen and oxygen. While oxygen is a useful byproduct the created hydrogen is used as a clean storable energy carrier or feedstock for numerous businesses. It is possible to operate the device with or without battery storage. When solar energy is combined with batteries excess solar energy may be stored for later use maximizing energy efficiency and guaranteeing a steady supply of electricity even in the absence of direct sunlight. On the other hand battery-free systems depend on the electrolyzer’s continuous power generation to convert solar energy into hydrogen during the day. In addition to allowing for the production of renewable hydrogenthis hybrid PV-solar and water electrolyzer setup contributes to grid stability by offering demand-side flexibility. Moreover the modularity of these systems enables scalability to meet diverse energy requirements spanning from residential to industrial applications thereby fostering a cleaner and more sustainable energy landscape. This review delves into various topologies for PV-driven electrolysis and conducts a thorough exploration of the dynamics of low-temperature water electrolyzers. Specifically it examines their integration with three primary technologies: Proton Exchange Membrane Alkaline and Anion Exchange Membrane shedding light on their implications for the broader integration landscape. Through detailed analysis and insights this study enriches the understanding of the potential and challenges inherent in the convergence of PV solar water electrolysis and renewable energy systems.

We present an optimization model of an energy district in South Italy that supplies baseload electricity and hydrogen services. The district is sized such that a nuclear reactor could provide these services. We define scenarios for 2050 to explore the system effects of discount rate sensitivity vetoes on technologies and cost uncertainties. We address the following issues relevant to decarbonization in South Italy: land-based wind and solar vs. exclusive solar rooftop extra cost of a veto on nuclear conservative assumptions on future storage technology and the role of pumped hydro storage lack of low-cost geological storage of hydrogen and the industrial competitiveness of this carrier and the methanation synergy with the agroforestry sector. Our results quantify the high system cost of vetoes on land-based wind and solar. Nuclear may enter the optimal mix only with a veto against onshore wind and a hypothesis of equal project risk hence an equal discount rate with renewables. Scenarios with land-based wind and solar obtain low-cost hydrogen and thus allow industrial uses for this carrier. The methanation synergy with the agroforestry sector does not offer a system cost advantage but improves the district’s configuration. The extra cost of full decarbonization relative to unregulated fossil gas is small with land-based wind and solar and significant with vetoes to these technologies.

This report is an output of the Clean Energy Technology Observatory (CETO). CETO's objective is to provide an evidence-based analysis feeding the policy making process and hence increasing the effectiveness of R&I policies for clean energy technologies and solutions. It monitors EU research and innovation activities on clean energy technologies needed for the delivery of the European Green Deal; and assesses the competitiveness of the EU clean energy sector and its positioning in the global energy market. CETO is being implemented by the Joint Research Centre for DG Research and Innovation in coordination with DG Energy.

Hydrogen produced from renewable sources has the potential to tackle various energy challenges from allowing cost-effective transportation of renewable energy from production to consumption regions to decarbonizing intensive energy consumption industries. Due to its application versatility and non-greenhouse gaseous emissions characteristics it is expected that hydrogen will play an important role in the decarbonization strategies set out for 2050. Currently there are some barriers and challenges that need to be addressed to fully take advantage of the opportunities associated with hydrogen. The present work aims to characterize the state of the art of different hydrogen production storage transport and distribution technologies which compose the hydrogen value chain. Based on the information collected it was possible to conclude the following: (i) Electrolysis is the frontrunner to produce green hydrogen at a large scale (efficiency up to 80%) since some of the production technologies under this category have already achieved a commercially available state; (ii) in the storage phase various technologies may be suitable based on specific conditions and purposes. Technologies of the physical-based type are the ones mostly used in real applications; (iii) transportation and distribution options should be viewed as complementary rather than competitive as the most suitable option varies based on transportation distance and hydrogen quantity; and (iv) a single value chain configuration cannot be universally applied. Therefore each case requires a comprehensive analysis of the entire value chain. Methodologies like life cycle assessment should be utilized to support the decision-making process.

Green hydrogen obtained from renewable electricity can play an essential role in the decarbonization of different sectors. The reliability of the data used to model the entire supply chain is a crucial parameter in Life Cycle Assessment. In this study the authors show how photovoltaic and wind electricity supply chains influence the carbon footprint of green H2. While most published studies rely on default datasets from commercial libraries the current work exploits the actual supply chain of the PV panels and builds an updated average European wind turbine supply chain. The updated values for PV-based H2 experiencing a 40–60% reduction are 2.7 and 1.8 kg CO2 eq./kg H2 for the UK and Italy. The carbon footprint of UK offshore wind-based H2 can be reduced up to 24% and get close to 0.6 kg CO2 eq./kg H2. The findings emphasize the sensitivity of the final climate profile generated by the processes upstream of the electrolysis system.

The existing gas transmission pipeline network can be a convenient and cost-effective way to transport hydrogen. However hydrogen can cause hydrogen embrittlement (HE) of the steels used in pipeline construction. HE is typically manifested as a reduction in fracture toughness and ductility. To ensure structural integrity it is thus important to understand the fracture toughness of pipeline steels in hydrogen gas at pipeline pressures. This paper reviews (i) the influence of hydrogen on the fracture toughness of pipeline steels and (ii) the phenomena that occurs during fracture toughness tests of pipeline steel in air and hydrogen. Also reviewed are (i) the in fluence of hydrogen on tensile properties and (ii) the diffusion and solubility of hydrogen in pipeline steels under conditions relevant to hydrogen transport in gas transmission pipelines.

Proton exchange membrane electrolyzers are an attractive technology for hydrogen production due to their high efficiency low maintenance cost and scalability. To receive these benefits however electrolyzers require high power reliability and have relatively high demand. Due to their intermittent nature integrating renewable energy sources like solar and wind has traditionally resulted in a supply too sporadic to consistently power a proton exchange membrane electrolyzer. This study develops an electrolyzer model operating with renewable energy sources at a highly instrumented university site. The simulation uses dynamic models of photovoltaic solar and wind systems to develop models capable of responding to changing climatic and seasonal conditions. The aim therefore is to observe the feasibility of operating a proton exchange membrane system fuel cell yearround at optimal efficiency. To address the problem of feasibility with dynamic renewable generation a case study demonstrates the proposed energy management system. A site with a river onsite is chosen to ensure sufficient wind resources. Aside from assessing the feasibility of pairing renewable generation with proton exchange membrane systems this project shows a reduction in the intermittency plaguing previous designs. Finally the study quantifies the performance and effectiveness of the PEM energy management system design. Overall this study highlights the potential of proton exchange membrane electrolysis as a critical technology for sustainable hydrogen production and the importance of modeling and simulation techniques in achieving its full potential.

This article presents a study on the distributed optimization operation method for micro-energy grid clusters within an electric thermal and hydrogen integrated energy system. The research focuses on precisely modeling the Power-toHydrogen (P2H) conversion process in electrolytic cells by considering their startup characteristics. An optimization operation model is established with each micro-energy grid as the principal entity to cater to their individual interests and demands. The Alternating Direction Method of Multipliers (ADMM) algorithm is adopted for distributed solution. Case studies demonstrate that the connection topology between micro-energy grids significantly impacts the total operating cost and the effectiveness of the ADMM algorithm is validated through a comparison with centralized optimization approaches.

Compression ignition engines will still be predominant in the naval sector: their high efficiency high torque and heavy weight perfectly suit the demands and architecture of ships. Nevertheless recent emission legislations impose limitations to the pollutant emissions levels in this sector as well. In addition to post-treatment systems it is necessary to reduce some pollutant species and therefore the study of combustion strategies and new fuels can represent valid paths for limiting environmental harmful emissions such as CO2 . The use of methane in dual fuel mode has already been implemented on existent vessels but the progressive decarbonization will lead to the utilization of carbon-neutral or carbon-free fuels such as in the last case hydrogen. Thanks to its high reactivity nature it can be helpful in the reduction of exhaust CH4 . On the contrary together with the high temperatures achieved by its oxidation hydrogen could cause uncontrolled ignition of the premixed charge and high emissions of NOx. As a matter of fact a source of ignition is still necessary to have better control on the whole combustion development. To this end an optimal and specific injection strategy can help to overcome all the before-mentioned issues. In this study three-dimensional numerical simulations have been performed with the ANSYS Forte® software (version 19.2) in an 8.8 L dual fuel engine cylinder supplied with methane hydrogen or hydrogen–methane blends with reference to experimental tests from the literature. A new kinetic mechanism has been used for the description of diesel fuel surrogate oxidation with a set of reactions specifically addressed for the low temperatures together with the GRIMECH 3.0 for CH4 and H2 . This kinetics scheme allowed for the adequate reproduction of the ignition timing for the various mixtures used. Preliminary calculations with a one-dimensional commercial code were performed to retrieve the initial conditions of CFD calculations in the cylinder. The used approach demonstrated to be quite a reliable tool to predict the performance of a marine engine working under dual fuel mode with hydrogen-based blends at medium load. As a result the system modelling shows that using hydrogen as fuel in the engine can achieve the same performance as diesel/natural gas but when hydrogen totally replaces methane CO2 is decreased up to 54% at the expense of the increase of about 76% of NOx emissions.

The transport sector is considered to be a significant contributor to greenhouse gas emissions as this sector emits about one-fourth of global CO2 emissions. Transport emissions contribute toward climate change and have been linked to adverse health impacts. Therefore alternative and sustainable transport options are urgent for decarbonising the transport sector and mitigating those issues. Hydrogen fuel cell vehicles are a potential alternative to conventional vehicles which can play a significant role in decarbonising the future transport sector. This study critically analyses the recent works related to hydrogen fuel cell integration into vehicles modelling and experimental investigations of hydrogen fuel cell vehicles with various powertrains. This study also reviews and analyses the performance energy management strategies lifecycle cost and emissions of fuel cell vehicles. Previous literature suggested that the fuel consumption and well-to-wheel greenhouse gas emissions of hydrogen fuel cell-powered vehicles are significantly lower than that of conventional internal combustion vehicles. Hydrogen fuel cell vehicles consume about 29–66 % less energy and cause approximately 31–80 % less greenhouse gas emissions than conventional vehicles. Despite this the lifecycle cost of hydrogen fuel cell vehicles has been estimated to be 1.2–12.1 times higher than conventional vehicles. Even though there has been recent progress in energy management in hydrogen fuel cell electric vehicles there are a number of technical and economic challenges to the commercialisation of hydrogen fuel cell vehicles. This study presents current knowledge gaps and details future research directions in relation to the research advancement of hydrogen fuel cell vehicles.

It is likely that blending hydrogen into natural gas grids could contribute to economy-wide decarbonization while retaining some of the benefits that natural gas networks offer energy systems. Hydrogen injection into existing natural gas infrastructure is recognised as a key solution for energy storage during periods of low electricity demand or high variable renewable energy penetration. In this scenario natural gas networks provide an energy vector parallel to the electricity grid offering additional energy transmission capacity and inherent storage capabilities. By incorporating green hydrogen into the NG network it becomes feasible to (i) address the current energy crisis (ii) reduce the carbon intensity of the gas grid and (iii) promote sector coupling through the utilisation of various renewable energy sources. This study gives an overview of various interchangeability indicators and investigates the permissible ratios for hydrogen blending with two types of natural gas distributed in Tunisia (ANG and MNG). Additionally it examines the impact of hydrogen injection on energy content variation and various combustion parameters. It is confirmed by the data that ANG and MNG can withstand a maximum hydrogen blend of up to 20%. The article’s conclusion emphasises the significance of evaluating infrastructure and safety standards related to Tunisia’s natural gas network and suggests more experimental testing of the findings. This research marks a critical step towards unlocking the potential of green hydrogen in Tunisia.

Ammonia a molecule that is gaining more interest as a fueling vector has been considered as a candidate to power transport produce energy and support heating applications for decades. However the particular characteristics of the molecule always made it a chemical with low if any benefit once compared to conventional fossil fuels. Still the current need to decarbonize our economy makes the search of new methods crucial to use chemicals such as ammonia that can be produced and employed without incurring in the emission of carbon oxides. Therefore current efforts in this field are leading scientists industries and governments to seriously invest efforts in the development of holistic solutions capable of making ammonia a viable fuel for the transition toward a clean future. On that basis this review has approached the subject gathering inputs from scientists actively working on the topic. The review starts from the importance of ammonia as an energy vector moving through all of the steps in the production distribution utilization safety legal considerations and economic aspects of the use of such a molecule to support the future energy mix. Fundamentals of combustion and practical cases for the recovery of energy of ammonia are also addressed thus providing a complete view of what potentially could become a vector of crucial importance to the mitigation of carbon emissions. Different from other works this review seeks to provide a holistic perspective of ammonia as a chemical that presents benefits and constraints for storing energy from sustainable sources. State-of-the-art knowledge provided by academics actively engaged with the topic at various fronts also enables a clear vision of the progress in each of the branches of ammonia as an energy carrier. Further the fundamental boundaries of the use of the molecule are expanded to real technical issues for all potential technologies capable of using it for energy purposes legal barriers that will be faced to achieve its deployment safety and environmental considerations that impose a critical aspect for acceptance and wellbeing and economic implications for the use of ammonia across all aspects approached for the production and implementation of this chemical as a fueling source. Herein this work sets the principles research practicalities and future views of a transition toward a future where ammonia will be a major energy player.

The global green hydrogen rush is prone to repeat extractivist patterns at the expense of economies ecologies and communities in the production zones in the Global South. With a socio-ecological risk analysis grounded in energy water and environmental justice scholarship we systematically assess the risks of the ‘green’ hydrogen transition and related injustices arising in 28 countries in the Global South with regard to energy water land and global justice dimensions. Our findings show that risks materialize through the exclusion of affected communities and civil society the enclosure of land and resources for extractivist purposes and through the externalization of socio-ecological costs and conflicts. We further demonstrate that socio-ecological risks are enhanced through country-specific conditions such as water scarcity historical continuities such as post-colonial land tenure systems as well as repercussions of a persistently uneven global politico-economic order. Contributing to debates on power inequality and justice in the global green hydrogen transition we argue that addressing hydrogen risks requires a framework of environmental justice and a transformative perspective that encompasses structural shifts in the global economy including degrowth and a decentering of industrial hegemonies in the Global North.

This study evaluates the potential for large-scale green hydrogen production in Indonesia by utilizing renewable energy sources connected on-grid namely 50 MWp of solar panels and 35 MW of wind turbines as well as a hybrid system combining both with a capacity of 45 MW at a grid cost of $100/kWh in five strategic cities: Banyuwangi Kupang BauBau Banjarmasin and Ambon. Using HOMER Pro software various integrated energy system scenarios involving ion exchange membrane electrolysis and alkaline water electrolysis. Additionally the study assumes a project lifespan of 15 years a discount rate of 6.6% and an inflation rate of 2.54%. The results showed that Bau-Bau recorded the highest hydrogen production reaching more than 1.9 million kilograms per year with the lowest levelized cost of hydrogen of $0.65/kg in Scheme 2. On the other hand Kupang shows high costs for most schemes with the levelized cost reaching $1.10/kg. In addition to hydrogen the study also evaluated oxygen production as a by-product of electrolysis. Bau-Bau and Kupang recorded the highest oxygen production with Scheme 6 achieving more than 15 million kilograms per year. The cost of electricity production varies between cities with Banyuwangi having the lowest cost of electricity for wind energy at $80.9/MWh. The net present cost for renewable energy systems in Banyuwangi was $35.4 million for wind turbines while the photovoltaic+wind combination showed the highest cost at $116 million. These findings emphasize the importance of hybrid systems in improving hydrogen production efficiency and supporting sustainable energy transition in Indonesia.