Publications

The combustion emissions of the hydrogen-fueled engines are very clean but the problems of abnormal combustion and high NOx emissions limit their applications. Nowadays hydrogen engines use exhaust gas recirculation (EGR) technology to control the intensity of premixed combustion and reduce the NOx emissions. This study aims at improving the abnormal combustion and decreasing the NOx emissions of the hydrogen engine by applying a three-dimensional (3D) computational fluid dynamics (CFD) model of a single-cylinder hydrogen-fueled engine equipped with an EGR system. The results indicated that peak in-cylinder pressure continuously increased with the increase of the ignition advance angle and was closer to the top dead center (TDC). In addition the mixture was burned violently near the theoretical air–fuel ratio and the combustion duration was shortened. Moreover the NOx emissions the average pressure and the in-cylinder temperature decreased as the EGR ratio increased. Furthermore increasing the EGR ratio led to an increase in the combustion duration and a decrease in the peak heat release rate. EGR system could delay the spontaneous combustion reaction of the end-gas and reduce the probability of knocking. The pressure rise rate was controlled and the in-cylinder hot spots were reduced by the EGR system which could suppress the occurrence of the pre-ignition in the hydrogen engine.

As a promising substitute for fossil fuels hydrogen has emerged as a clean and renewable energy. A key challenge is the efcient production of hydrogen to meet the commercial-scale demand of hydrogen. Water splitting electrolysis is a promising pathway to achieve the efcient hydrogen production in terms of energy conversion and storage in which catalysis or electrocatalysis plays a critical role. The development of active stable and low-cost catalysts or electrocatalysts is an essential prerequisite for achieving the desired electrocatalytic hydrogen production from water splitting for practical use which constitutes the central focus of this review. It will start with an introduction of the water splitting performance evaluation of various electrocatalysts in terms of activity stability and efciency. This will be followed by outlining current knowledge on the two half-cell reactions hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in terms of reaction mechanisms in alkaline and acidic media. Recent advances in the design and preparation of nanostructured noble-metal and non-noble metal-based electrocatalysts will be dis‑ cussed. New strategies and insights in exploring the synergistic structure morphology composition and active sites of the nanostructured electrocatalysts for increasing the electrocatalytic activity and stability in HER and OER will be highlighted. Finally future challenges and perspectives in the design of active and robust electrocatalysts for HER and OER towards efcient production of hydrogen from water splitting electrolysis will also be outlined.

Among numerous techniques for the hydrogen production without harmful emissions especially avoiding the carbon dioxide emissions hydrogen technologies driven by geothermal energy represent an attractive solution. This paper is interested in the process by which the electricity generated from geothermal power plant that is operated using CO2 as heat transmission fluid is exploited for hydrogen production through water electrolysis. A numerical simulation is used to evaluate the potential for hydrogen production and to estimate the levelized cost of electrolytic hydrogen. We also present brief analysis of environmental issues including the carbon tax. The results show that the process has a good potential for geothermal hydrogen production is capable of producing about 22 kg/h of electrolytic hydrogen for the geothermal source of carbon dioxide mass flow rate of 40 kg/s and a temperature of 296 K. In economic regard the electric energy system costs are the major component of the total hydrogen production cost (more than 90%). The estimated cost of hydrogen is 8.24 $/kg H2. By including the carbon tax the cost of hydrogen production becomes far more competitive.

Power to gas (PTG) refers to the technology of converting power into energy-storage gas which can absorb excess power when there is excess power and release energy-storage gas when needed. Based on the carbon dioxide (CO2 ) emission of Karamay City in Northwest China this study designed a process flow of the CO2 absorption process and the hydrogen and CO2 methanation process in PTG technology. The results show that the efficiency of the CO2 absorption process was 91.5% and the methanation efficiency was 77.5%. The heat recovery module was set during the process and the total heat recovered was 17.85 MW. The cost of producing synthetic natural gas (SNG) in the PTG factory was 1782 USD/ton. In terms of cost the cost of hydrogen production from electrolyzed water accounted for the largest proportion. In terms of product profit the sale of pure oxygen was the largest part of the profit. At present the carbon emission reduction index profit brought by SNG production accounted for a small proportion. In the future with technological progress industrial upgrading and the improvement in the carbon trading market PTG technology is expected to become one of the ways to achieve carbon-emission-reduction targets.

To prevent climate change Europe and the world must shift to low-carbon and renewable energies. Hydrogen as an energy vector provides viable solutions for replacing polluting and carbon-emitting fossil fuels. Gaseous hydrogen can be stored underground and coupled with existing natural gas pipe networks. Salt cavern storage is the best suited technology to meet the challenges of new energy systems. Hydrogen storage caverns are currently operated in the UK and Texas. A preliminary risk analysis dedicated to underground hydrogen salt caverns highlighted the importance of containment losses (leaks) and the formation of gas clouds following blowouts whose ignition may generate dangerous phenomena such as jet fires unconfined vapor cloud explosions (UVCEs) or flashfires. A blowout is not a frequent accident in gas storage caverns. A safety valve is often set at a 30 m depth below ground level; it is automatically triggered following a pressure drop at the wellhead. Nevertheless a blowout remains to be one of the significant accidental scenarios likely to occur during hydrogen underground storage in salt caverns. In this paper we present modelling the subterraneous and aerial parts of a blowout on an EZ53 salt cavern fully filled with hydrogen.

Energy plays a crucial role in the sustainable development of modern nations. Today hydrogen is considered the most promising alternative fuel as it can be generated from clean and green sources. Moreover it is an efficient energy carrier because hydrogen burning only generates water as a byproduct. Currently it is generated from natural gas. However it can be produced using other methods i.e. physicochemical thermal and biological. The biological method is considered more environmentally friendly and pollution free. This paper aims to provide an updated review of biohydrogen production via photofermentation dark fermentation and microbial electrolysis cells using different waste materials as feedstocks. Besides the role of nanotechnology in enhancing biohydrogen production is examined. Under anaerobic conditions hydrogen is produced during the conversion of organic substrate into organic acids using fermentative bacteria and during the conversion of organic acids into hydrogen and carbon dioxide using photofermentative bacteria. Different factors that enhance the biohydrogen production of these organisms either combined or sequentially using dark and photofermentation processes are examined and the effect of each factor on biohydrogen production efficiency is reported. A comparison of hydrogen production efficiency between dark fermentation photofermentation and two-stage processes is also presented.

In this podcast David Ledesma talks with Rahmat Poudineh Senior Research Fellow and Aliaksei Patonia Research Fellow on issues and options with respect to long distance transportation of the hydrogen.

Hydrogen currently is mainly a local or regional commodity. If hydrogen is to become a truly global-traded commodity it needs to be transported over long transoceanic distances in an economical way. However unlike natural gas shipping compressed or liquefied hydrogen over long distances is very inefficient and expensive. At the same time hydrogen can be converted into multiple carriers with a higher energy density and higher transport capacity such as liquid ammonia toluene/methylcyclohexane (MCH) or methanol. These chemicals have their own advantages and drawbacks and their techno-economic characteristics in terms of boil-off gas and thermodynamic and conversion losses play a key role in the efficiency of transoceanic transportation of the hydrogen.

On the other hand apart from techno-economic features there are other factors to consider for long distance transportation of the hydrogen via its careers. Here such issues as safety public acceptance as well as legal and regulatory constraints may come into play. Another factor is the availability of the industries and infrastructures already developed around any of possible hydrogen carriers as well as their potential industrial applicability beyond hydrogen. Finally technological progress in other decarbonization applications and most importantly full commercialization of CCUS solutions is likely to dramatically change the approach towards long distance hydrogen transportation.

The podcast can be found on their website. 

The sustainable development of hydrogen energy is a priority task for a possible solution to 26 the global energy crisis. Hydrogen is a clean and renewable energy source that today is used 27 exclusively in the form of compressed gas or in liquefied form which prevents its widespread 28 use. Storing hydrogen in solid-state systems will not only increase the bulk density and 29 gravimetric capacity but will also have a positive impact on safety issues. From this point of 30 view the current review considers the latest research in the field of application of 1D 31 nanomaterials for solid-state hydrogen storage and also discusses the mechanisms of its 32 adsorption and desorption. Despite the high publication activity the use of 1D nanomaterials for 33 hydrogen storage has not been fully studied. In the current review modern developments in the 34 field of hydrogen storage using 1D nanomaterials and composites based on them are investigated 35 in detail and their problems and future prospects are discussed.

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

The effects of hydrogen-enriched biogas on combustion and emissions of a dual-fuel sparkignition engine with different hydrogen concentration ratios were studied numerically. A 1-cylinder spark ignition was used to perform a numerical simulation. To reveal the influence of the compression ratios on combustion and emissions of a gaseous engine the crankshaft of the engine was modified to generate different compression ratios of 8.5 9.0 9.4 10.0 and 10.4. The biogas contained 60 and 40% methane (CH4 ) and carbon dioxide (CO2 ) respectively while the hydrogen fractions used to enrich biogas were 10 20 and 30% of the mixture by volume. The ignition timing is fixed at 350 CA◦ . The results indicate that the in-cylinder pressure combustion temperature and combustion burning speed increase gradually with increasing hydrogen concentration due to the combustion characteristics of hydrogen in blends. As increasing the compression ratio NOx emissions increase proportionally while CO2 emissions decrease gradually. Almost no combustion process occurs as operating the compression ratio below 8.5 when using pure biogas. However adding 20% of hydrogen fraction could improve the combustion process significantly even at a low compression ratio.

Building heating is one of the sectors for which multiple decarbonisation options exist and current geopolitical tensions provide urgency to design adequate regional policies. Heat pumps and hydrogen boilers alongside alternative district heating systems are the most promising alternatives. Although a host of city or country-level studies exist it remains controversial what role hydrogen should play for building heating in the European Union compared with electrification and how blue and green hydrogen differ in terms of costs and environmental impacts. This works assesses the optimal technology mix for staying within planetary boundaries and the influence of international cooperation and political restrictions. To perform the analysis a bottom-up optimisation model was developed incorporating life cycle assessment constraints and covering production storage transport of energy and carbon dioxide as well as grid and non-grid connected end-users of heat. It was found that a building heating system within planetary boundaries is feasible through large-scale electrification via heat pumps although at a higher cost than the current system with abatement costs of around 200 €/ton CO2. Increasing interconnector capacity or onshore wind energy is found to be vital to staying within boundaries. A strong trade-off for hydrogen was identified with blue hydrogen being cost-competitive but vastly unsustainable (when applied to heating) and green hydrogen being 2–3 times more expensive than electrification while still transgressing several planetary boundaries. The insights from this work indicate that heat pumps and renewable electricity should be prioritised over hydrogen-based heating in most cases and grid-stability and storage aspects explored further while revealing a need for policy instruments to mitigate increased costs for consumers.

Beside steam reforming methane pyrolysis is an alternative method for hydrogen production. ‘Turquoise’ hydrogen with solid carbon is formed in the pyrolysis process contrary to ‘grey’ or ‘blue’ hydrogen via steam methane reforming where waste carbon dioxide is produced. Thermal pyrolysis is conducted at higher temperatures but catalytic decomposition of methane (CDM) is a promising route for sustainable hydrogen production. CDM is generally carried out over four types of catalyst: nickel carbon noble metal and iron. The applied reactors can be fixed bed fluidized bed plasma bed or molten-metal reactors. Two main advantages of CDM are that (i) carbon-oxide free hydrogen ideal for fuel cell applications is formed and (ii) the by-product can be tailored into carbon with advanced morphology (e.g. nanofibers nanotubes). The aim of this review is to reveal the very recent research advances of the last two years achieved in the field of this promising prospective technology.

Political decarbonisation commitments and outcompeting renewable electricity costs are disrupting energy systems. This foresight study prepares stakeholders for this dynamic reactive change by examining visions that constitute a probable plausible and possible component of future energy systems. Visions were extrapolated through an expert review of energy technologies and Australian case studies. ‘Probable–Abundant’ envisages a high penetration of solar and wind with increased value of balancing services: batteries pumped hydro and transmission. This vision is exemplified by the South Australian grid where variable and distributed sources lead generation. ‘Plausible–Traded’ envisages power and power fuel exports given hydrogen and high-voltage direct-current transmission advances reflected by public and private sector plans to leverage rich natural resources for national and intercontinental exchanges. ‘Possible–Zero’ envisages the application of carbon removal and nuclear technologies in response to the escalating challenge of deep decarbonisation. The Australian critical minerals strategy signals adaptations of high-emission industries to shifting energy resource values. These visions contribute a flexible accessible framework for diverse stakeholders to discuss uncertain energy systems changes and consider issues from new perspectives. Appraisal of preferred futures allows stakeholders to recognise observed changes as positive or negative and may lead to new planning aspirations.

Northern countries face a unique challenge in decarbonizing heating demands. This study compares two pathways to reduce carbon emissions from building heating by (1) replacing natural gas heaters with electric heat pumps or (2) replacing natural gas with renewable gas. Optimal annual system cost and capacity requirements for Metro Vancouver Canada are assessed for each pathway under nine scenarios. Results show that either pathway can be lower cost but the range of costs is more narrow for the renewable gas pathway. System cost is sensitive to heat demand with colder temperatures favouring the renewable gas pathway and milder temperatures favouring the electrification pathway. These results highlight the need for a better understanding of heating profiles and associated energy system requirements.

Global climate targets have highlighted the need for a whole-systems approach to decarbonisation one that includes targeted national policy and industry specific change. Situated within this context this research examines policy and pricing barriers to decarbonisation of the UK steel industry. Here the techno-economic modelling of UK green steelmaking provides a technical contribution to analysis of pricing barriers and policy solutions to these barriers in the UK specifically but also to the broader industrial decarbonisation literature. Estimated costs and associated emissions projections reveal relevant opportunities for UK steel in contributing to national climate and emissions targets. Modelling demonstrates that green steelmaking options have been put at price disadvantages compared to emissions-intensive incumbents and that fossil-free hydrogen-based steel-making has lower emissions and lower levelised costs than carbon capture and storage options including top gas recycling blast furnace (TGR-BF) with CCS and HIsarna smelter with CCS. Two primary policy recommendations are made: the removal of carbon pricing discrepancies and reductions in industrial electricity prices that would level the playing field for green steel producers in the UK. The research also provides relevant policy considerations for the international community in other industrial decarbonisation efforts and the policies that must accompany these decarbonisation choices.

This paper discusses fuel cell electric vehicles and more specifically the challenges and development of hydrogen-fueled buses for people accessing this transportation in cities and urban environments. The study reveals the main innovations and challenges in the field of hydrogen bus deployment and identifies the most common approaches and errors in this area by extracting and critically appraising data from sources important to the energy perspective. Three aspects of the development and horizons of fuel cell electric buses are reviewed namely energy consumption energy efficiency and energy production. The first is associated with the need to ensure a useful and sustainable climate-neutral public transport. Herewith the properties of the hydrogen supply of electric buses and their benefits over gasoline gas and battery vehicles are discussed. The efficiency issue is related to the ratio of consumed and produced fuel in view of energy losses. Four types of engines–gasoline diesel gas and electrical–are evaluated in terms of well-to-wheel tank-to-wheel delivery and storage losses. The third problem arises from the production operating and disposal constraints of the society at the present juncture. Several future-oriented initiatives of the European Commission separate countries and companies are described. The study shows that the effectiveness of the FCEBs depends strongly on the energy generation used to produce hydrogen. In the countries where the renewables are the main energy sources the FCEBs are effective. In other regions they are not effective enough yet although the future horizons are quite broad.

For the first time we quantify cost footprint and reliability implications of deploying hydrogen-based generation in off-grid electric vehicle charging stations (CS) using an optimization model coupled with a geographic information system (GIS) analysis for the city of Riyadh Saudi Arabia. We also account for the challenges associated with wind energy deployment as a candidate generation technology within city centers. The analysis was restricted to carbon-free technologies: photovoltaics (PV) wind battery and hydrogen fuel-cells. At current prevailing technology costs hydrogen can reduce the required footprint of off-grid CSs by 25% at a small incremental cost increase without impacting the charging reliability. By 2030 however hydrogen will simultaneously provide the footprint and cost advantages. If we allow as little as 5% of the annual load to be unmet the required footprint of the CS decreases by 60%. The levelized cost of energy values for the CS by 2030 can range between 0.13 and 0.20 $/kWh depending on learning-curve assumptions. The footprints calculated are then mapped to five land parcel categories in Riyadh: gas station hospital mall school and university. Incorporating hydrogen in CS design increases the number of parcels that could accommodate CSs by 15e45% via reducing the required PV array (i.e. footprint).

The world is undergoing a substantial energy transition with an increasing share of intermittent sources of energy on the grid which is increasing the challenges to operate the power grid reliably. An option that has been receiving much focus after the COVID pandemic is the development of a hydrogen economy. Challenges for a hydrogen economy are the high investment costs involved in compression storage and long-distance transportation. This paper analyses an innovative proposal for the creation of hydrogen ocean links. It intends to fill existing gaps in the creation of a hydrogen economy with the increase in flexibility and viability for hydrogen production consumption compression storage and transportation. The main concept behind the proposals presented in this paper consists of using the fact that the pressure in the deep sea is very high which allows a thin and cheap HDPE tank to store and transport large amounts of pressurized hydrogen in the deep sea. This is performed by replacing seawater with pressurized hydrogen and maintaining the pressure in the pipes similar to the outside pressure. Hydrogen Deep Ocean Link has the potential of increasing the interconnectivity of different regional energy grids into a global sustainable interconnected energy system.

With the development of fuel cells multi-stack fuel cell system (MFCS) for high power application has shown tremendous development potential owing to their obvious advantages including high efficiency durability reliability and pollution-free. Accordingly the state-of-the-art of MFCS is summarized and analyzed to advance its research. Firstly the MFCS applications are presented in high-power scenarios especially in transportation applications. Then to further investigate the MFCS MFCS including hydrogen and air subsystem thermal and water subsystem multi-stack architecture and prognostics and health monitoring are reviewed. It is noted that prognostics and health monitoring are investigated rarely in MFCS compared with previous research. In addition the efficiency and durability of MFCS are not only related to the application field and design principle but also the energy management strategy (EMS). The reason is that the EMS is crucial for lifespan cost and efficiency in the multi-stack fuel cell system. Finally the challenge and development potential of MFCS is proposed to provide insights and guidelines for future research.

With the increasing concern about global energy crisis and environmental pollution the integrated renewable energy system has gradually become one of the most important ways to achieve energy transition. In the context of the rapid development of hydrogen energy industry the proportion of hydrogen energy in the energy system has gradually increased. The conversion between various energy sources has also become more complicated which poses challenges to the planning and construction of park-level integrated energy systems (PIES). To solve this problem we propose a bi-level planning model for an integrated energy system with hydrogen energy considering multi-stage investment and carbon trading mechanism. First the mathematical models of each energy source and energy storage in the park are established respectively and the independent operation of the equipment is analyzed. Second considering the operation state of multi-energy coordination a bi-level planning optimization model is established. The upper level is the capacity configuration model considering the variable installation time of energy facilities while the lower level is the operation optimization model considering several typical daily operations. Third considering the coupling relationship between upper and lower models the bi-level model is transformed into a solvable single-level mixed integer linear programming (MILP) model by using Karush–Kuhn–Tucker (KKT) condition and big-M method. Finally the proposed model and solution methods are verified by comprehensive case studies. Simulation results show that the proposed model can reduce the operational cost and carbon emission of PIES in the planning horizon and provide insights for the multi-stage investment of PIES.

Hydrogen will be a central cross-sectoral energy carrier in the decarbonization of the European energy system. This paper investigates how a large-scale deployment of green hydrogen production affects the investments in transmission and generation towards 2060 analyzes the North Sea area with the main offshore wind projects and assesses the development of an offshore energy hub. Results indicate that the hydrogen deployment has a tremendous impact on the grid development in Europe and in the North Sea. Findings indicate that total power generation capacity increases around 50%. The offshore energy hub acts mainly as a power transmission asset leads to a reduction in total generation capacity and is central to unlock the offshore wind potential in the North Sea. The effect of hydrogen deployment on power prices is multifaceted. In regions where power prices have typically been lower than elsewhere in Europe it is observed that hydrogen increases the power price considerably. However as hydrogen flexibility relieves stress in high-demand periods for the grid power prices decrease in average for some countries. This suggests that while the deployment of green hydrogen will lead to a significant increase in power demand power prices will not necessarily experience a large increase.

The increasing penetration of renewable energies will make new storage technologies indispensable in the future. Power-to-Gas (PtG) is one long-term storage technology that exploits the existing gas infrastructure. However this technology faces technical economic environmental challenges and questions. This contribution presents the final results of a large research project which attempted to address and provide answers to some of these questions for Baden-Württemberg (south west Germany). Three energy scenarios out to 2040 were defined one oriented towards the Integrated Energy and Climate Protection Concept of the Federal State Government and two alternatives. Timely-resolved load profiles for gas and electricity for 2015 2020 2030 and 2040 have been generated at the level of individual municipalities. The profiles include residential and industrial electrical load gas required for heating (conventional and current-controlled CHP) as well as gas and electricity demand for mobility. The installation of rooftop PV-plants and wind power plants is projected based on bottom up cost-potential analyses which account for some social acceptance barriers. Residential load profiles are derived for each municipality. In times with negative residual load the PtG technology could be used to convert electricity into hydrogen or methane. The detailed analysis of four structurally-different model regions delivered quite different results. While in large cities no negative residual load is likely due to the continuously high demand and strong networks rural areas with high potentials for renewables could encounter several thousand hours of negative residual load. A cost-effective operation of PtG would only be possible under favorable conditions including high full load hours a strong reduction in costs and a technical improvement of efficiency. Whilst these conditions are not expected to appear in the short to mid-term but may occur in the long term in energy systems with very high shares of renewable energy sources

Solid oxide electrolysis cell is the leading technology for production of green hydrogen by high temperature electrolysis. However optimization of existing reference materials constituting the cell and development of innovative materials remain critical for solid oxide electrolysis cell. In particular they are key to reach performance and durability targets compatible with a commercialization for the three main markets identified as follows: large-scale H2 production Power-to-X and Power-to-Power. This short review summarizes the latest progress in research and development of alternative and innovative materials for solid oxide electrolysis cells with a main focus on cathode-supported cell materials. A brief description of the layers constituting the solid oxide electrolysis cell is provided with the associated current state-of-the-art materials. A further emphasis on the most promising alternative and innovative materials for each layer follows based on the major aspects from an industrial perspective to reach a competitive hydrogen production cost for the main targeted markets: performance durability scaling up/manufacturing ability and operational flexibility.

The recent strong increase in the penetration of renewable energy sources (RESs) in medium-voltage distribution grids (MVDNs) has raised the need for congestion management in such grids as they were not designed for this new condition. This paper examines to what extent producing green hydrogen through electrolyzers can profitably contribute to congestion alleviation in MVDNs in the presence of high amounts of RES as well as flexible consumers of electricity and a local heat system. To address this issue an incentive-based method for improving flexibility in MVDNs is used which is based on a single-leader–multiple-followers game formulated by bi-level mathematical programming. At the upper level the distribution system operator who is the leader of this game determines dynamic prices as incentives at each node based on the levels of generation and load. Next at the lower level providers of flexibility including producers using electrolyzers price-responsive power consumers heat consumers as well as heat producers respond to these incentives by reshaping their output and consumption patterns. The model is applied to a region in the North of The Netherlands. The obtained results demonstrate that converting power to hydrogen can be an economically efficient way to reduce congestion in MVDNs when there is a high amount of RES. However the economic value of electrolyzers as providers of flexibility to MVDNs decreases when more other options for flexibility provision exist.

The RePowerEU plan [1] and the European Hydrogen Strategy [2] recognise the important role that the transport of hydrogen will play in enabling the penetration of renewable hydrogen in Europe. To implement the European Hydrogen Strategy it is important to understand whether the transport of hydrogen is cost effective or whether hydrogen should be produced where it is used. If transporting hydrogen makes sense a second open question is how long the transport route should be for the cost of the hydrogen to still be competitive with locally produced hydrogen. JRC has performed a comprehensive study regarding the transport of hydrogen. To investigate which renewable hydrogen delivery pathways are favourable in terms of energy demand and costs JRC has developed a database and an analytical tool to assess each step of the pathways and used it to assess two case studies. The study reveals that there is no single optimal hydrogen delivery solution across every transport scenario. The most cost effective way to deliver renewable hydrogen depends on distance amount final use and whether there is infrastructure already available. For distances compatible with the European territory compressed and liquefied hydrogen solutions and especially compressed hydrogen pipelines offer lower costs than chemical carriers do. The repurposing of existing natural gas pipelines for hydrogen use is expected to significantly lower the delivery cost making the pipeline option even more competitive in the future. By contrast chemical carriers become more competitive the longer the delivery distance (due to their lower transport costs) and open up import options from suppliers located for example in Chile or Australia.

An increasing demand in the marine industry to reduce emissions led to investigations into more efficient power conversion using fuels with sustainable production pathways. Solid Oxide Fuel Cells (SOFCs) are under consideration for long-range shipping because of its high efficiency low pollutant emissions and fuel flexibility. SOFC systems also have great potential to cater for the heat demand in ships but the heat integration is not often considered when assessing its feasibility. This study evaluates the electrical and heat efficiency of a 100 kW SOFC system for marine applications fuelled with methane methanol diesel ammonia or hydrogen. In addition cathode off-gas recirculation (COGR) is investigated to tackle low oxygen utilisation and thus improve heat regeneration. The software Cycle Tempo is used to simulate the power plant which uses a 1D model for the SOFCs. At nominal conditions the highest net electrical efficiency (LHV) was found for methane (58.1%) followed by diesel (57.6%) and ammonia (55.1%). The highest heat efficiency was found for ammonia (27.4%) followed by hydrogen (25.6%). COGR resulted in similar electrical efficiencies but increased the heat efficiency by 11.9% to 105.0% for the different fuels. The model was verified with a sensitivity analysis and validated by comparison with similar studies. It is concluded that COGR is a promising method to increase the heat efficiency of marine SOFC systems.

Rapid industrialization is consuming too much energy and non-renewable energy resources are currently supplying the world’s majority of energy requirements. As a result the global energy mix is being pushed towards renewable and sustainable energy sources by the world’s future energy plan and climate change. Thus hydrogen has been suggested as a potential energy source for sustainable development. Currently the production of hydrogen from fossil fuels is dominant in the world and its utilization is increasing daily. As discussed in the paper a large amount of hydrogen is used in rocket engines oil refining ammonia production and many other processes. This paper also analyzes the environmental impacts of hydrogen utilization in various applications such as iron and steel production rocket engines ammonia production and hydrogenation. It is predicted that all of our fossil fuels will run out soon if we continue to consume them at our current pace of consumption. Hydrogen is only ecologically friendly when it is produced from renewable energy. Therefore a transition towards hydrogen production from renewable energy resources such as solar geothermal and wind is necessary. However many things need to be achieved before we can transition from a fossil-fuel-driven economy to one based on renewable energy

With the constant increase in variable renewable energy production in electricity and district heating systems integration with the gas system is a way to provide flexibility to the overall energy system. In the sustainable transition towards a zero-emission energy system traditional natural gas can be substituted by renewable gasses derived from anaerobic digestion or thermal gasification and hydrogen. In this paper we present a methodology for modelling renewable gas options and limits on biomass resources across sectors in the energy optimisation model Balmorel. Different scenarios for socio-economic pathways to emission neutral electricity and district heating systems in Denmark Sweden Norway and Germany show that a renewable based energy system benefits from a certain percentage of gas as a supplement to other flexibility options like interconnectors. Especially upgraded biogas from anaerobic digestion serves as a substitute for natural gas in all scenarios. Allocating only 10% of available biomass to the electricity and district heating sector leads to full exploitation of the scarce biomass resource by boosting biogas and syngas with hydrogen. The need for renewable gasses is highest in Germany and least in Norway where hydro-power provides flexibility in terms of storable and dispatchable electricity production. The scenarios show that a required ‘‘late sprint" from fossils to achieve a zero-emission energy system in 2050 causes (1) significant higher accumulated emissions and (2) a system which strongly relies on fuels also in an emission free system instead of stronger integration of the electricity and district heating systems through electrification as well as stronger integration of the power systems across countries through interconnectors.

The injection of hydrogen into existing gas grids is acknowledged as a promising option for decarbonizing gas systems and enhancing the integration among energy sectors. Nevertheless it affects the hydraulics and the quality management of networks. When the network is fed by multiple infeed sites and hydrogen is fed from a single injection point non-homogeneous hydrogen distribution throughout the grid happens to lead to a reduction of the possible amount of hydrogen to be safely injected within the grid. To mitigate these impacts novel operational schemes should therefore be implemented. In the present work the modulation of the outlet pressures of gas infeed sites is proposed as an effective strategy to accommodate larger hydrogen volumes into gas grids extending the area of the network reached by hydrogen while keeping compliance with quality and hydraulic restrictions. A distribution network operated at two cascading pressure tiers interfaced by pressure regulators constitutes the case study which is simulated by a fluid-dynamic and multi-component model for gas networks. Results suggest that higher shares of hydrogen and other green gases can be introduced into existing distribution systems by implementing novel asset management schemes with negligible impact on grid operations.

In recent years the problem of environmental pollution especially the emission of greenhouse gases has attracted people’s attention to energy infrastructure. At present the fuel consumed by transportation mainly comes from fossil energy and the strong traffic demand has a great impact on the environment and climate. Fuel cell electric vehicles (FCEVs) use hydrogen energy as a clean alternative to fossil fuels taking into account the dual needs of transportation and environmental protection. However due to the low power density and high manufacturing cost of hydrogen fuel cells their combination with other power supplies is necessary to form a hybrid power system that maximizes the utilization of hydrogen energy and prolongs the service life of hydrogen fuel cells. Therefore the hybrid power system control mode has become a key technology and a current research hotspot. This paper first briefly introduces hydrogen fuel cells then summarizes the existing hybrid power circuit topology categorizes the existing technical solutions and finally looks forward to the future for different scenarios of hydrogen fuel cell hybrid power systems. This paper provides reference and guidance for the future development of renewable hydrogen energy and hydrogen fuel cell hybrid electric vehicles.

The pathway to zero carbon emissions passing through carbon emissions reduction is mandatory in the shipping industry. Regarding the various methodologies and technologies reviewed for this purpose Life Cycle Cost Analysis (LCCA) has been used as an excellent tool to determine economic feasibility and sustainability and to present directions. However insufficient commercial applications cause a conflict of opinion on which fuel is the key to decarbonisation. Many LCCA comparison studies about eco-friendly ship propulsion claim different results. In order to overcome this and discover the key factors that affect the overall comparative analysis and results in the maritime field it is necessary to conduct the comparative analysis considering more diverse case ships case routes and various types that combine each system. This study aims to analyse which greener fuels are most economically beneficial for the shipping sector and prove the factors influencing different results in LCCA. This study was conducted on hydrogen ammonia and electric energy which are carbon-free fuels among various alternative fuels that are currently in the limelight. As the power source a PEMFC and battery were used as the main power source and a solar PV system was installed as an auxiliary power source to compare economic feasibility. Several cost data for LCCA were selected from various feasible case studies. As the difficulty caused by the storage and transportation of hydrogen and ammonia should not be underestimated in this study the LCCA considers not only the CapEx and OpEx but also fuel transport costs. As a result fuel cell propulsion systems with hydrogen as fuel proved financial effectiveness for short-distance ferries as they are more inexpensive than ammonia-fuelled PEMFCs and batteries. The fuel cost takes around half of the total life-cycle cost during the life span.

Global energy and environmental issues are becoming increasingly serious and the promotion of clean energy and green transportation has become a common goal for all countries. In the logistics industry traditional fuels such as diesel and natural gas can no longer meet the requirements of energy and climate change. Hydrogen fuel cell logistics vehicles are expected to become the mainstream vehicles for future logistics because of their “zero carbon” advantages. The GREET model is computer simulation software developed by the Argonne National Laboratory in the USA. It is extensively utilized in research pertaining to the energy and environmental impact of vehicles. This research study examines four types of logistics vehicles: hydrogen fuel cell vehicles (FCVs) electric vehicles LNG-fueled vehicles and diesel-fueled vehicles. Diesel-fueled logistics vehicles are currently the most abundant type of vehicle in the logistics sector. LNG-fueled logistics vehicles are considered as a short-term alternative to diesel logistics vehicles while electric logistics vehicles are among the most popular types of new-energy vehicles currently. We analyze and compare their well-to-wheels (WTW) energy consumption and emissions with the help of GREET software and conduct lifecycle assessments (LCAs) of the four types of vehicles to analyze their energy and environmental benefits. When comparing the energy consumption of the four vehicle types electric logistics vehicles (EVs) have the lowest energy consumption with slightly lower energy consumption than FCVs. When comparing the nine airborne pollutant emissions of the four vehicle types the emissions of the FCVs are significantly lower than those of spark-ignition internal combustion engine logistics vehicles (SI ICEVs) compression-ignition direct-injection internal combustion engine logistics vehicles (CIDI ICEVs) and EVs. This study fills a research gap regarding the energy consumption and environmental impact of logistics vehicles in China.

Hypothesis.<br/>The large-scale implementation of hydrogen economy requires immense storage spaces to facilitate the periodic storage/production cycles. Extensive modelling of hydrogen transport in porous media is required to comprehend the hydrogen-induced complexities prior to storage to avoid energy loss. Wettability of hydrogen-brine-rock systems influence flow properties (e.g. capillary pressure and relative permeability curves) and the residual saturations which are all essential for subsurface hydrogen systems.<br/>Model.<br/>This study aims to understand which parameters critically control the contact angle for hydrogen-brine-rock systems using the surface force analysis following the DLVO theory and sensitivity analysis. Furthermore the effect of roughness is studied using the Cassie-Baxter model.<br/>Findings.<br/>Our results reveal no considerable difference between H2 and other gases such as N2. Besides the inclusion of roughness highly affects the observed apparent contact angles and even lead to water-repelling features. It was observed that contact angle does not vary significantly with variations of surface charge and density at high salinity which is representative for reservoir conditions. Based on the analysis it is speculated that the influence of roughness on contact angle becomes significant at low water saturation (i.e. high capillary pressure).

Hydrogen sensors especially those operating at high temperatures are essential tools for the emerging hydrogen economy. Monitoring hydrogen under process conditions to control the reactions for detecting confined species is crucial to the safe widespread use and public acceptance of hydrogen as fuel. Hydrogen sensors must have a sensitivity ranging from traces of hydrogen (parts per million (ppm)) up to levels near the lower explosive limit (LEL = 4% H2 in the air) for safety reasons. Furthermore they need to operate in cryogenic ambient and high-temperature environments. Herein emphasis is given to hydrogen sensors based on solid oxide electrolytes (operating at high temperatures) in particular oxygen ion and proton conductors. The review is devoted to potentiometric amperometric and combined amperometric-potentiometric hydrogen sensors. Experimental results already reported in the international literature are presented and analyzed to reveal the configuration principle of operation and the applied solid electrolytes and electrodes of the high-temperature hydrogen sensors. Additionally an amperometric sensor able to detect hydrogen and steam in atmospheric air through a two-stage procedure is presented and thoroughly discussed. The discussion reveals that high-temperature hydrogen sensors face different challenges in terms of the electrodes and solid electrolytes to be used depending on the operating principle of each sensor type.

The measures needed to limit global warming pose a particular challenge to current fossil fuel exporters who must not only decarbonise their local energy systems but also compensate for the expected decline in fossil fuel revenues. One possibility is seen in the export of green hydrogen. Using Algeria as a case study this paper analyses how different levels of ambition in hydrogen exports energy efficiency and fuel switching affect the costoptimal expansion of the power sector for a given overall emissions reduction path. Despite falling costs for photovoltaics and wind turbines the results indicate that in countries with very low natural gas prices such as Algeria a fully renewable electricity system by 2050 is unlikely without appropriate policy measures. The expansion of renewable energy should therefore start early given the high annual growth rates required which will be reinforced by additional green hydrogen exports. In parallel energy efficiency is a key factor as it directly mitigates CO2 emissions from fossil fuels and reduces domestic electricity demand which could instead be used for hydrogen production. Integrating electrolysers into the power system could potentially help to reduce specific costs through load shifting. Overall it seems advisable to analyse hydrogen exports together with local decarbonisation in order to better understand their interactions and to reduce emissions as efficiently as possible. These results and the methodology could be transferred to other countries that want to become green hydrogen exporters in the future and are therefore a useful addition for researchers and policy makers.

This report analyses five case study reports in-depth across five EU countries as part of a broader analytical and critical exercise. This analytical work seeks to contribute to the development of new models for regional and local authorities aiming to boost support for Green Transition of their economies through smarter innovation policies using the smart specialisation (S3) approach. The work covered five regions from across the European Union representing a diversity of approaches to using S3 for Green Transition: the Basque Country in Spain the Centro region in Portugal the region of East and North Finland the region of Western Macedonia in Greece and the region of West Netherlands. The case studies included in this report consists of three sections on (i) Profile of the region and key development challenges; (ii) Innovation strategies and policies for green transition: incorporating societal challenges; (iii) Understanding and monitoring innovationled green transition. Drawing together the different elements presented the conclusion provides a summary overview of the case and the authors’ opinion on it.

Hydrogen addition affects the composition of exhaust gases in vehicles. However the effects of hydrogen addition to compression ignition engines in running vehicles have not been evaluated. Hydrogen‑mixed air was introduced into the air intake of a truck equipped with a direct‑ injection diesel engine and running on a chassis dynamometer to investigate the effect of hydrogen addition on fuel consumption and exhaust gas components. The reduction in diesel consumption and the increase in hydrogen energy share (HES) showed almost linear dependence where the percentage decrease in diesel consumption is approximately 0.6 × HES. The percentage reduction of CO2 showed a one‑to‑one relationship to the reduction in diesel consumption. The reduction in emissions of CO PM and hydrocarbons (except for ethylene) had one to one or a larger correlation with the reduction of diesel consumption. On the other hand it was observed that NOx emissions increased and the percentage increase of NOx was 1.5~2.0 times that of HES. The requirement for total energy supply was more when hydrogen was added than for diesel alone. In the actual running mode only 50% of the energy of added hydrogen was used to power the truck. As no adjustments were made to the engine in this experiment a possible disadvantage that could be improved by adjusting the combustion conditions.

The production storage and use of hydrogen for energy purposes will become increasingly important during the energy transition. One way to use hydrogen is to apply it to power vehicles. This green technological solution affects low-emissions transport which is beneficial and important especially in cities. The authors of this article analyzed the use of hydrogen production infrastructure for bus propulsion in the city of Katowice (Poland). The methods used in the study included a greedy algorithm and cost methods which were applied for the selection of vehicles and identification of the infrastructure for the production storage and refueling of hydrogen as well as to conduct the economic analysis during this term. The article presented the complexity of the techno-economic analysis of the infrastructure and its installation. The key element was the selection of the number of vehicles to the hydrogen production possibilities of an electrolyser and capabilities of the storage and charging infrastructure.

Norwegian offshore wind farms may be able to supply power to offshore oil and gas platforms in the near future thanks to the expeditious development of offshore wind technology. This would result in a reduction in CO2 emissions from oil and gas offshore installations which are currently powered predominantly by gas turbines. The challenge with using wind power is that offshore oil and gas installations require a fairly constant and stable source of power whereas wind power typically exhibits significant fluctuations over time. The purpose of this study is to perform a technical feasibility evaluation of using wind power to supply an offshore oil and gas installation on the basis of dynamic process simulations. Throughout the study only the topside processing system is considered since it is the most energy-intensive part of an oil and gas facility. An offshore field on the Norwegian Continental Shelf is used as a case study. The results indicate that when the processing system operates in steady-state conditions it cannot be powered solely by wind energy and another power source is required to compensate for low wind power generation intervals. An alternative would be to store wind energy during periods of high generation (e.g. by producing hydrogen or ammonia) and use it during periods of low generation. Utilizing energy storage methods wind energy can be continuously used for longer periods of time and provide a suitable constant power source for the studied case. Higher constant power can also be provided by increasing the efficiency of energy recovery and storage processes. Alternatively these two technologies may be integrated with gas turbines if the required storage cannot be provided or higher power is required. It was estimated that the integration of wind energy could result in noticeable reductions in CO2 emissions for the case study. Additionally according to the results the production storage and reuse of hydrogen and ammonia on-site may be viable options for supplying power.

Hydrogen has the physical and chemical characteristics of being flammable explosive and prone to leakage and its safety is the main issue faced by the promotion of hydrogen as an energy source. The most common scene in vehicle application is the longitudinal wind generated by driving and the original position of hydrogen concentration sensors (HCSs) did not consider the influence of longitudinal wind on the hydrogen leakage trajectory. In this paper the computational fluid dynamics (CFD) software STAR CCM 2021.1 is used to simulate the hydrogen leakage and diffusion trajectories of fuel cell vehicles (FCVs) at five different leakage locations the longitudinal wind speeds of 0 km/h 37.18 km/h and 114 km/h and it is concluded that longitudinal wind prolongs the diffusion time of hydrogen to the headspace and reduces the coverage area of hydrogen in the headspace with a decrease of 81.35%. In order to achieve a good detection effect of fuel cell vehicles within the longitudinal wind scene based on the simulated hydrogen concentration–time matrix the scene clustering method based on vector similarity evaluation was used to reduce the leakage scene set by 33%. Then the layout position of HCSs was optimized according to the proposed multi-scene full coverage response time minimization model and the response time was reduced from 5 s to 1 s.

Smart energy networks provide an effective means to accommodate high penetrations of variable renewable energy sources like solar and wind which are key for the deep decarbonisation of energy production. However given the variability of the renewables as well as the energy demand it is imperative to develop effective control and energy storage schemes to manage the variable energy generation and achieve desired system economics and environmental goals. In this paper we introduce a hybrid energy storage system composed of battery and hydrogen energy storage to handle the uncertainties related to electricity prices renewable energy production and consumption. We aim to improve renewable energy utilisation and minimise energy costs and carbon emissions while ensuring energy reliability and stability within the network. To achieve this we propose a multi-agent deep deterministic policy gradient approach which is a deep reinforcement learning-based control strategy to optimise the scheduling of the hybrid energy storage system and energy demand in real time. The proposed approach is model-free and does not require explicit knowledge and rigorous mathematical models of the smart energy network environment. Simulation results based on real-world data show that (i) integration and optimised operation of the hybrid energy storage system and energy demand reduce carbon emissions by 78.69% improve cost savings by 23.5% and improve renewable energy utilisation by over 13.2% compared to other baseline models; and (ii) the proposed algorithm outperforms the state-of-the-art self-learning algorithms like the deep-Q network.

Green hydrogen promises to be critical in achieving a sustainable and renewable energy transition. As green hydrogen is produced with renewables green hydrogen could become an energy storage medium of the future and even substitute the current unsustainable grey or blue hydrogen used in the industry. Bringing this transition into reality for instance in Germany there are visions to rapidly build hydrogen facilities in Africa and export the produced green hydrogen to Europe. One problem however is that these visions presumably conflict with the visions of actors within Africa. Therefore this study aims to provide an initial assessment of African stakeholders’ visions for future energy exports and renewable energy expectations. By comparing visions from Germany and Africa this assessment was conducted to identify differences in green energy and hydrogen visions that could lead to conflict and similarities that could be the basis for cooperation. The National Hydrogen Strategy outlines the German visions which clarifies that Germany will have to import green hydrogen to meet its green transition target. In this context of future energy export demand a partnership between German and African researchers on assessing green hydrogen potentials in Africa started. The African visions were explored by surveying the partners from different African countries working on the project. The results revealed that while both sides see the need for an immediate transition to renewable energy the African side is not envisioning the immediate export of green hydrogen. Based on the responses the partners are primarily concerned with improving the continent’s still deficient energy access for both the population and industry. Nevertheless this African perspective greatly emphasises cross-border cooperation where both sides can realise their visions. In the case of Germany that German investment could build infrastructure which would benefit the receiving African country or countries and open up the possibility for the envisioned green hydrogen export to Europe.

The energy production market based on hydrogen technologies is an innovative solution that will allow the industry to achieve climate neutrality in the future in Poland and in the world. The paper presents the idea of using hydrogen as a modern energy carrier and devices that in cooperation with renewable energy sources produce the so-called green hydrogen and the applicable legal acts that allow for the implementation of the new technology were analyzed. Energy transformation is inevitable and according to reports on good practices in European Union countries hydrogen and the hydrogen value chain (production transport and transmission storage use in transport and energy) have wide potential. Thanks to joint projects and subsidies from the EU initiatives supporting hydrogen technologies are created such as hydrogen clusters and hydrogen valleys and EU and national strategic programs set the main goals. Poland is one of the leaders in hydrogen production both in the world and in Europe. Domestic tycoons from the energy refining and chemical industries are involved in the projects. Eight hydrogen valleys that have recently been created in Poland successfully implement the assumptions of the “Polish Hydrogen Strategy until 2030 with a perspective until 2040” and “Energy Policy of Poland until 2040” which are in line with the assumptions of the most important legal acts of the EU including the European Union’s energy and climate policy the Green Deal and the Fit for 55 Package. The review of the analysis of the development of hydrogen technologies in Poland shows that Poland does not differ from other European countries. As part of the assumptions of the European Hydrogen Strategy and the trend related to the management of energy surpluses electrolyzers with a capacity of at least 6 GW will be installed in Poland in 2020–2024. It is also assumed that in the next phase planned for 2025–2030 hydrogen will be a carrier in the energy system in Poland. Poland as a member of the EU is the creator of documents that take into account the assumptions of the European Union Commission and systematically implement the assumed goals. The strategy of activities supporting the development of hydrogen technologies in Poland and the value chain includes very extensive activities related to among others obtaining hydrogen using hydrogen in transport energy and industry developing human resources for the new economy supporting the activities of hydrogen valley stakeholders building hydrogen refueling stations and cooperation among Poland Slovakia and the Czech Republic as part of the HydrogenEagle project.

Green hydrogen is central to the global energy transition. This paper introduces a renewable hydrogen production system model that optimizes hydrogen production on a worldwide 50 km × 50 km grid considering country-specific investment risks. Besides the renewable energy’s impact on the hydrogen production system (HPS) design we analyze the effect of country-specific interest rates on the levelized cost of hydrogen (LCOH) production. Over one-third (40.0%) of all cells have an installed solar PV capacity share between 50% and 70% 76.4% have a hybrid (onshore wind and solar PV) configuration. Hydrogen storage is deployed rather than battery storage to balance hydrogen production via electrolysis and hydrogen demand. Hybrid HPSs can significantly reduce the LCOH production compared to non-hybrid designs whereas country-specific interest rates can lead to significant increases diminishing the relative competitiveness of countries with abundant renewable energy resources compared to countries with fewer resources but fewer investment risks.

The utilization of hydrogen for reciprocating internal combustion engines remains a subject that necessitates thorough research and careful analysis. This paper presents a study on the co-combustion of hydrogen with diesel fuel and biodiesel (RME) in a compression-ignition piston engine operating at maximum load with a hydrogen content of up to 34%. The research employed engine indication and exhaust emissions measurement to assess the engine’s performance. Engine indication allowed for the determination of key combustion stages including ignition delay combustion time and the angle of 50% heat release. Furthermore important operational parameters such as indicated pressure thermal efficiency and specific energy consumption were determined. The evaluation of dual-fuel engine stability was conducted by analyzing variations in the coefficient of variation in indicated mean effective pressure. The increase in the proportion of hydrogen co-combusted with diesel fuel and biodiesel had a negligible impact on ignition delay and led to a reduction in combustion time. This effect was more pronounced when using biodiesel (RME). In terms of energy efficiency a 12% hydrogen content resulted in the highest efficiency for the dual-fuel engine. However greater efficiency gains were observed when the engine was powered by RME. It should be noted that the hydrogen-powered engine using RME exhibited slightly less stable operation as measured by the COVIMEP value. Regarding emissions hydrogen as a fuel in compression ignition engines demonstrated favorable outcomes for CO CO2 and soot emissions while NO and HC emissions increased.

To cope with climate change emerging fuels- hydrogen ammonia and methanol- have been proposed as promising energy carriers that will replace part of the liquefied natural gas (LNG) in future maritime scenarios. Energy efficiency is an important indicator for evaluating the system but the maritime supply system for emerging fuels has yet to be revealed. In this study the energy efficiency of the maritime supply chain of hydrogen ammonia methanol and natural gas is investigated considering processes including production storage loading transport and unloading. A sensitivity analysis of parameters such as ambient temperature storage time pipeline length and sailing time is also carried out. The results show that hydrogen (2.366%) has the highest daily boil-off gas (BOG) rate and wastes more energy than LNG (0.413%) with ammonia and methanol both being lower than LNG. The recycling of BOG is of great importance to the hydrogen supply chain. When produced from renewable energy sources methanol (98.02%) is the most energy efficient followed by ammonia with hydrogen being the least (89.10%). This assessment shows from an energy efficiency perspective that ammonia and methanol have the potential to replace LNG as the energy carrier of the future and that hydrogen requires efficient BOG handling systems to increase competitiveness. This study provides some inspirations for the design of global maritime supply systems for emerging fuels.

Accurate evaluation of thermo‑fluid dynamic characteristics in tanks is critically important for designing liquid hydrogen tanks for small‑scale hydrogen liquefiers to minimize heat leakage into the liquid and ullage. Due to the high costs most future liquid hydrogen storage tank designs will have to rely on predictive computational models for minimizing pressurization and heat leakage. Therefore in this study to improve the storage efficiency of a small‑scale hydrogen liquefier a three‑ dimensional CFD model that can predict the boil‑off rate and the thermo‑fluid characteristics due to heat penetration has been developed. The prediction performance and accuracy of the CFD model was validated based on comparisons between its results and previous experimental data and a good agreement was obtained. To evaluate the insulation performance of polyurethane foam with three different insulation thicknesses the pressure changes and thermo‑fluid characteristics in a partially liquid hydrogen tank subject to fixed ambient temperature and wind velocity were investigated nu‑ merically. It was confirmed that the numerical simulation results well describe not only the temporal variations in the thermal gradient due to coupling between the buoyance and convection but also the buoyancy‑driven turbulent flow characteristics inside liquid hydrogen storage tanks with differ‑ ent insulation thicknesses. In the future the numerical model developed in this study will be used for optimizing the insulation systems of storage tanks for small‑scale hydrogen liquefiers which is a cost‑effective and highly efficient approach.

This paper presents a systematic investigation that encompasses the safety assessment of a fuel preparation room (FPR) intended for a hydrogen-fueled ship. The primary objective is to determine the appropriate ventilation strategy to mitigate the risks associated with potential hydrogen leakage. The study focuses on a case involving an FPR measuring 10.2 m × 5.3 m × 2.65 m which is part of a 750 DWT hydrogen-powered fishing vessel. To identify the potential events leading to hydrogen dispersion an event tree analysis is conducted. Additionally existing regulations and guidelines related to the safety assessments of hydrogen leakage in enclosed areas are summarized and analyzed. Computational fluid dynamics FLACS-CFD are utilized for the consequence analysis in order to evaluate the impact of ventilation on hydrogen dispersion and concentration within the FPR. The research findings indicate significant effects of ventilation on the hazards and safety assessments of FPRs and high-pressure fuel gas supply systems. The study highlights that hydrogen vapor tends to accumulate at the ceiling and in the corners and spaces created by the equipment. The position and size of ventilation openings greatly influence the dispersion of hydrogen leakage. Proper ventilation design including top inlet ventilation and outlet ventilation on the opposite side helps to maintain a safe FPR by facilitating the efficient dispersion of hydrogen vapor. Moreover locating inlet ventilation on the same side as the outlet ventilation is found to hinder dispersion while the cross-ventilation achieved by placing inlets and outlets on opposite sides enhances airflow and dispersion. Consequently it is recommended to prioritize the structural design of FPRs and implement enhanced safety measures. Additionally updating the relevant regulations to address these concerns is strongly advised.

Utilizing renewable energy sources to produce hydrogen is essential for promoting cleaner production and improving power utilization especially considering the growing use of fossil fuels and their impact on the environment. Selecting the most efficient method for distributing power and capacity is a critical issue when developing hybrid systems from scratch. The main objective of this study is to determine how a backup system affects the performance of a microgrid system. The study focuses on power and hydrogen production using renewable energy resources particularly solar and wind. Based on photovoltaics (PVs) wind turbines (WTs) and their combinations including battery storage systems (BSSs) and hydrogen technologies two renewable energy systems were examined. The proposed location for this study is the northwestern coast of Saudi Arabia (KSA). To simulate the optimal size of system components and determine their cost-effective configuration the study utilized the Hybrid Optimization Model for Multiple Energy Resources (HOMER) software (Version 3.16.2). The results showed that when considering the minimum cost of energy (COE) the integration of WTs PVs a battery bank an electrolyzer and a hydrogen tank brought the cost of energy to almost 0.60 USD/kWh in the system A. However without a battery bank the COE increased to 0.72 USD/kWh in the same location because of the capital cost of system components. In addition the results showed that the operational life of the fuel cell decreased significantly in system B due to the high hours of operation which will add additional costs. These results imply that long-term energy storage in off-grid energy systems can be economically benefited by using hydrogen with a backup system.

Widely available and low-cost solar photovoltaics and wind power can enable production of renewable electricity-based hydrogen at many locations throughout the world. Hydrogen is expected to emerge as an important energy carrier constituting some of the final energy demand; however its most important role will be as feedstock for further processing to e-fuels e-chemicals and e-steel. Apart from meeting their own hydrogen demand countries may have opportunities to export hydrogen to countries with area limitations or higher production costs. This paper assesses the feasibility of e-hydrogen imports to Germany and Finland from two case regions with a high availability of low-cost renewable electricity Chile and Morocco in comparison to domestic supply. Special attention is paid to the transport infrastructure which has a crucial impact on the economic viability of imports via two routes shipping and pipelines. This study has found that despite lower e-hydrogen production costs in Morocco and Chile compared to Germany and Finland additional transportation costs make imports of e-hydrogen economically unattractive. In early 2020s imported fuel costs are 39–79% and 34–100% higher than e-hydrogen produced in Germany and Finland respectively. In 2050 imported e-hydrogen is projected to be 39–70% more expensive than locally produced e-hydrogen in Germany and 43–54% in the case of Finland. e-Hydrogen may become a fuel that is mostly produced domestically and may be feasible for imports only in specific locations. Local e-hydrogen production may also lower dependence on imports enhance energy security and add jobs.