Denmark

The power-to-methanol (PtMeOH) will play a crucial role as a form of renewable chemical energy storage. In this paper PtMeOH techno-economics are assessed using the promising configuration from the previous work (Mbatha et al. [1]). This study evaluated the effect of parameters such as the CO2 emission tax electricity price and CAPEX reduction on the product methanol economic parity with respect to a reference case. Superior to previous economic studies a scenario where an existing methanol synthesis infrastructure is 100 % retrofitted with the promising electrolyser is assessed in terms of its economics and the associated economic parity. The volatile South African electricity market is considered as a case study. The sensitivity of the PtMeOH and green H2 profitability are checked. Grid-connected and standalone renewable energy PtMeOH scenarios are assessed. Foremost generalisable effect trends of these parameters on the net present value (NPV) and the levelized cost of methanol(LCOMeOH) and H2 (LCOH2) are discussed. The results show that economic parity of H2 (LCOH2 = current selling price = 4.06 €/kg) can be reached with an electricity price of 30 €/MWh and 70 % of the CAPEX. While the LCOMeOH will still be above 2 €/kg at 80 % of the CAPEX and electricity price of 20 €/MWh. This indicates that even if the CAPEX reduces to 20 % of its original in this study and the electricity price reduces to about 20 €/MWh the LCOMEOH will still not reach economic parity (LCOMeOH > current selling price = 0.44 €/kg). The results show that to make the retrofitted plant with a minimum of 20 years of life span profitable a feasible reduction in the electricity price to below 10 €/MWh along with favourable incentives such as CO2 credit and reduction in CAPEX particularly that of the electrolyser and treatment of the PtMeOH as a multiproduct plant will be required.

Hydrogen jet fire occurs with high probability when hydrogen leaks from high-pressure equipment. The hydrogen jet fire is characterized by its high velocity and energy. Computational Fluid Dynamics (CFD) numerical analysis is a prominent way to predict the potential hazards associated with hydrogen jet fire. Validation of the CFD model is essential to ensure and quantify the accuracy of numerical results. This study focuses on the validation of the hydrogen jet fire model using Fire Dynamic Simulation (FDS). Hydrogen release is modeled using high-speed Lagrangian particles released from a virtual nozzle thus avoiding the modeling of the actual nozzle. The mesh size sensitivity analysis of the model is carried out in a container-size domain with 0.04m – 0.08m resolution of the jet. The model is validated by comparing gas temperatures and heat fluxes with test data. The promising results demonstrated that the model could predict the hazardous influence of the jet fire.

Hydrogen energy is recognized by many European governments as an important part of the development to achieve a more sustainable energy infrastructure. Great efforts are spent to build up a hydrogen supply chain to support the increasing number of hydrogen-powered vehicles. Naturally these vehicles will use the common traffic infrastructure. Thus it has to be ensured these infrastructures are capable to withstand the hazards and associated risks that may arise from these new technologies. In order to have an appropriate assessment tool for hydrogen vehicles transport through tunnels a new QRA methodology is developed and presented here. In Europe the PIARC is a very common approach. It is therefore chosen as a starting point for the new methodology. It provides data on traffic statistics accident frequencies tunnel geometries including certain prevention and protection measures. This approach is enhanced by allowing better identification of hazards and their respective sources for hydrogen vehicles. A detailed analysis of the accident scenarios that are unique for hydrogen vehicles hereunder the initiating events severity of collision types that may result in a release of hydrogen gas in a tunnel and the location of such an accident are included. QRA enables the assessment and evaluation of scenarios involving external fires or vehicles that burst into fire because of an accident or other fire sources. Event Tree Analysis is the technique used to estimate the event frequencies. The consequence analysis includes the hazards from blast waves hydrogen jet fires DDT.

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 topic of energy islands is currently a focal point in the push for the energy transition. An ambitious project in the North Sea aims to build an offshore wind-powered electrolyser for green hydrogen production. Power-to-X (PtX) is a process of converting renewable electricity into hydrogen-based energy carriers such as natural gas liquid fuels and chemicals. PtH2 represents a subset of PtX wherein hydrogen is the resultant green energy from the conversion process. Many uncertainties surround PtH2 plants affecting the economic success of the investment and making the price of hydrogen and the levelized cost of hydrogen (LCOH) of this technology uncompetitive. Several studies have analysed PtH2 layouts to identify the hydrogen price without considering how component capacities and external inputs affect the breakeven price. Unlike previous works this paper investigates component capacity dependencies under variables such as wind and hydrogen demand shape for dedicated/non-dedicated system layouts. To this end the techno-economic analysis finds the breakeven price optimising the components to reach the lowest selling price. Results show that the hydrogen price can reach 2.2 €/kg for a non-dedicated system for certain combinations of maximum demand and electrolyser capacity. Furthermore the LCOH analysis revealed that the offshore wind electrolyser system is currently uncompetitive with hydrogen production from carbon-based technologies but is competitive with renewable technologies. The sensitivity analysis reveals the green electricity price in the non-dedicated case for which a dedicated system has a lower optimum hydrogen price. The price limit for the dedicated case is 116 €/MWh.

Safety and reliability have long been recognized as key issues for the development commercialization and implementation of new technologies and infrastructure and hydrogen systems are no exception to this rule. Reliability engineering quantitative risk assessment (QRA) and knowledge exchange each play a key role in proactive addressing safety – before problems happen – and help us learn from problems if they happen. Many international research activities are focusing on both reliability and risk assessment for hydrogen systems. However the element of knowledge exchange is sometimes less visible. To support international collaboration and knowledge exchange the International Energy Agency (IEA) convened a new Technology Collaboration Program “Task 43: Safety and Regulatory Aspects of Emerging Large Scale Hydrogen Energy Applications” started in June 2022. Within Task 43 Subtask E focuses on Hydrogen Systems Safety. This paper discusses the structure of the Hydrogen Systems Safety subtask and the aligned activities and introduces opportunities for future work.

Hydrogen energy plays a vital role in the transition towards a carbon-neutral society but faces challenges in storage and transport as well as in production due to fluctuations in renewable electricity generation. Ammonia (NH3 ) as a carbon-neutral hydrogen carrier offers a promising solution to the energy storage and transport problem. To realize its potential and support the development of a hydrogen economy exploring NH3 synthesis in a decentralized form that integrates with distributed hydrogen production systems is highly needed. In this study a computational fluid dynamics (CFD) model for the Ruthenium (Ru) catalysts-based Haber– Bosch reactor is developed. First a state-of-the-art kinetic model comprehensively describing the complex catalytic reaction is assessed for its sensitivity and applicability to temperature pressure and conversion. Then the kinetic model is integrated into the CFD model and its accuracy is verified through comparison with experimental data obtained from different Ru-based catalysts and operation conditions. Detailed CFD results for a given case are presented offering a visual understanding of thermal gradients and species distributions inside the reactor. Finally a CFD-based parametric study is performed to reveal the impacts of key operation parameters and optimize the NH3 synthesis reactor. The results show that the NH3 production rate is predominantly influenced by temperature with a two-fold difference observed for every 30 ◦C variation while pressure primarily affects the equilibrium. Additionally the affecting mechanism of space velocity is thoroughly discussed and the best value for efficient NH3 synthesis is found to be 180000 h−1. In conclusion the CFD model and simulation results provide valuable insights for the design and control of decentralized NH3 synthesis reactor and operation contributing to the advancement of sustainable energy technologies.

This paper investigates the feasibility of hydrogen-powered hybrid electric vehicles as a solution to transportation-related pollution. It focuses on optimizing energy use to improve efficiency and reduce emissions. The study details the creation and real-time performance assessment of a hydrogen hybrid electric vehicle (HHEV)system using an STM32F407VG board. This system includes a fuel cell (FC) as the main energy source a battery (Bat) to provide energy during hydrogen supply disruptions and a supercapacitor (SC) to handle power fluctuations. A multi-agent-based artificial intelligence tool is used to model the system components and an energy management algorithm (EMA) is applied to optimize energy use and support decision-making. Real Global Positioning System (GPS) data are analyzed to estimate energy consumption based on trip and speed parameters. The EMA developed and implemented in real-time using Matlab/Simulink(2016) identifies the most energy-efficient routes. The results show that the proposed vehicle architecture and management strategy effectively select optimal routes with minimal energy use.

Aviation is one of the most challenging sectors to electrify directly due to its high energy density demands. Hydrogen offers a pathway for indirect electrification in such sectors enabling sustainable aviation fuels (SAF) production when combined with a carbon source. SAF produced via methanol or Fischer-Tropsch (FT) synthesis (e-SAF) has higher volumetric density than hydrogen remains liquid under standard conditions and can be used as a direct drop-in fuel. Certain FT-based e-SAF pathways are already certified for use in blends enhancing their appeal for sustainable aviation. This study evaluates e-SAF pathways in terms of resource efficiency and costs for different carbon sources. The results from both a standalone and system-level perspective indicate that biomass gasification-sourced carbon is the most energy-efficient pathway given biomass availability. For point-source and direct air capture pathways electricity costs for renewable hydrogen dominate the overall costs comprising about 70 % of total e-SAF costs. Given cheap renewable electricity and by-product revenues e-SAF can achieve price levels of 0.5–1.1 €/litre which is cost-competitive with their fossil-based counterparts. A breakeven electricity price of 9–29 €/MWh is needed for e-SAF made via a point source-based CO2 pathway compared with a moderate aviation fossil fuel price of 0.5 €/litre.

A liquid air energy storage (LAES) system is a promising Carnot battery configuration capable of efficiently recovering waste heat and cold energy carriers. Among these liquid hydrogen (LH₂) regasification presents a significant opportunity due to its high exergy content and its regasification temperature which aligns well with the liquid air liquefaction process. While most existing studies focus on integrating LAES with liquid natural gas (LNG) regasification or improving hydrogen liquefaction via liquid air regasification this work takes a novel approach by enhancing liquid air liquefaction through the utilization of waste cold from LH₂ regasification. Additionally this study explores an economic innovation the valorization of clean dry air discharged by LAES which has not been extensively examined in prior literature. A novel LAES configuration is proposed and subjected to a techno-economic analysis comparing its performance with a stand-alone LAES system. Results show that the proposed integration increases round-trip efficiency by 15 % reduces the levelized cost of storage by 60 % and achieves a payback period of under 10 years. These findings provide valuable insights for both academia and industry advancing the development of more efficient and economically viable LAES systems.

This second edition of the European Maritime Transport Environmental Report (EMTER 2025) examines the progress made towards achieving Europe′s decarbonisation targets and environmental goals for the maritime sector while indicating the most important trends key challenges and opportunities. The objective was to update the indicators developed for the first report analyse new datasets and fill existing gaps to provide a data and knowledge-based assessment of the maritime transport sector′s transition to sustainability.

Aviation is of crucial importance for the transportation sector and fundamental for the economy as it facilitates trade and private travel. Nonetheless this sector is responsible for a great amount of global carbon dioxide emissions exceeding 920 million tonnes annually. Alternative energy fuels (AEFs) can be considered as a promising solution to tackle this issue with the potential to lower greenhouse gas emissions and reduce reliance on fossil fuels in the aviation industry. A life cycle analysis is performed considering an aircraft running on conventional jet fuel and various alternative fuels (biojet methanol and DME) including hydrogen and ammonia. The comparative assessment investigates different fuel production pathways including the following: JETA-1 and biojet fuels via hydrotreated esters and fatty acids (HEFAs) as well as hydrogen and ammonia employing water electrolysis using wind and solar photovoltaic collectors. The outputs of the assessment are quantified in terms of carbon dioxide equivalent emissions acidification eutrophication eco-toxicity human toxicity and carcinogens. The life cycle phases included the following: (i) the construction maintenance and disposal of airports; (ii) the operation and maintenance of aircrafts; and (iii) the production transportation and utilisation of aviation fuel in aircrafts. The results suggest that hydrogen is a more environmentally benign alternative compared to JETA-1 biojet fuel methanol DME and ammonia.

The present study proposes and thoroughly examines a novel approach for the effective hybridization of solar and wind sources based on hydrogen storage to increase grid stability and lower peak load. The parabolic trough collector vanadium chloride thermochemical cycle hydrogen storage tank alkaline fuel cells thermal energy storage and absorption chiller make up the suggested smart system. Additionally the proposed system includes a wind turbine to power the electrolyzer unit and minimize the size of the solar system. A rule-based control technique establishes an intelligent two-way connection with energy networks to compensate for the energy expenses throughout the year. The transient system simulation (TRNSYS) tool and the engineering equation solver program are used to conduct a comprehensive techno-economic-environmental assessment of a Swedish residential building. A four-objective optimization utilizing MATLAB based on the grey wolf algorithm coupled with an artificial neural network is used to determine the best trade-off between the indicators. According to the results the primary energy saving carbon dioxide reduction rate overall cost and purchased energy are 80.6 % 219 % 14.8 $/h and 24.9 MWh at optimal conditions. From the scatter distribution it can be concluded that fuel cell voltage and collector length should be maintained at their lowest domain and the electrode area is an ineffective parameter. The suggested renewable-driven smart system can provide for the building’s needs for 70 % of the year and sell excess production to the local energy network making it a feasible alternative. Solar energy is far less effective in storing hydrogen over the winter than wind energy demonstrating the benefits of combining renewable energy sources to fulfill demand. By lowering CO2 emissions by 61758 kg it is predicted that the recommended smart renewable system might save 7719 $ in environmental costs equivalent to 6.9 ha of new reforestation.

Achieving a net-zero energy system in Europe by 2050 will likely require large-scale deployment of hydrogen and seasonal energy storage to manage variability in renewable supply and demand. This study addresses two key objectives: (1) to develop a modeling framework that integrates seasonal storage into a stochastic multihorizon capacity expansion model explicitly capturing tactical uncertainty across timescales; and (2) to assess the impact of seasonal hydrogen storage on long-term investment decisions in European power and hydrogen infrastructure under three hydrogen demand scenarios. To this end the multi-horizon stochastic programming model EMPIRE is extended with tactical stages within each investment period enabling operational decisions to be modeled as a multi-stage stochastic program. This approach captures short-term uncertainty while preserving long-term investment foresight. Results show that seasonal hydrogen storage considerably enhances system flexibility displacing the need for up to 600 TWh/yr of dispatchable generation in Europe after 2040 and sizing down cross-border hydrogen transmission capacities by up to 12%. Storage investments increase by factors of 5–14 which increases the investments in variable renewables and improve utilization particularly solar. Scenarios with seasonal storage also show up to 6% lower total system costs and more balanced infrastructure deployment across regions. These findings underline the importance of modeling temporal uncertainty and seasonal dynamics in long-term energy system planning.

This study explores the feasibility of producing biohydrogen from winery wastewater using a dual-chamber microbial electrolysis cell (MEC). A mixed microbial consortium pre-adapted to heavy-metal environments and enriched with Geobacter sulfurreducens was anaerobically cultivated from diverse waste streams. Over 5000 h of development the MEC system was progressively adapted to winery wastewater enabling long-term electrochemical stability and high organic matter degradation. Upon winery wastewater addition (5% v/v) the system achieved a sustained hydrogen production rate of (0.7 ± 0.3) L H2 L −1 d −1 with an average current density of (60 ± 4) A m−3 and COD removal efficiency exceeding 55% highlighting the system’s resilience despite the presence of inhibitory compounds. Coulombic efficiency and cathodic hydrogen recovery reached (75 ± 4)% and (87 ± 5)% respectively. Electrochemical impedance spectroscopy provided mechanistic insight into charge transfer and biofilm development correlating resistive parameters with biological adaptation. These findings demonstrate the potential of MECs to simultaneously treat agro-industrial wastewaters and recover energy in the form of hydrogen supporting circular resource management strategies.

Air travel demand is rising rapidly and the aviation sector is relying on technology to decouple environmental impacts from its growth. Using Sweden as a case study we assessed the absolute environmental sustainability of medium-distance air travel in 2050 positioning the aviation sector's environmental impacts in relation to the planetary limits. We employed a novel framework that integrates prospective life cycle assessment and absolute environmental sustainability assessment methodologies. Our findings suggest that projected medium-distance air travel powered by e-kerosene or liquid hydrogen could have life cycle environmental impacts that overshoot global climate change and biodiversity loss thresholds by several orders of magnitude. Based on our case results for Sweden for aviation to develop within the planetary limits we recommend cross-sector collaboration to address environmental impacts from fossil-free energy supplies and the establishment of integrated targets that incorporate broader environmental issues. Given the unlikelihood of decoupling growth from environmental impacts policymakers and the aviation sector should consider concurrently supporting technological development and implementing measures to manage air travel demand.