Applications & Pathways

This paper aims at the development and validation of a computational fluid dynamic (CFD) model for simulations of the refuelling process through the entire equipment of the hydrogen refuelling station (HRS). The absence of such models hinders the design of inherently safer refuelling protocols for an arbitrary combination of HRS equipment hydrogen storage parameters and environmental conditions. The CFD model is validated against the complete process of refuelling lasting 195s in Test No.1 performed by the National Renewable Energy Laboratory (NREL). The test equipment includes high-pressure tanks of HRS pressure control valve (PCV) valves pipes breakaway hose and nozzle all the way up to three onboard tanks. The model accurately reproduced hydrogen temperature and pressure through the entire line of HRS equipment. A standout feature of the CFD model distinguishing it from simplified models is the capability to predict temperature non-uniformity in onboard tanks a crucial factor with significant safety implications.

This article presents a comprehensive description of the safety system of a real installation that comprises PV panels lithium-ion batteries an electrolyzer H2 storage a fuel cell and a barium chloride/ammonia thermochemical prototype for heat recovery and cooling production. Such a system allows for the increase of the overall efficiency of the H2 chain by exploiting the waste heat and transforming it into a cooling effect particularly useful in tropical regions like French Polynesia. The study provides a great deal of detail regarding practical aspects of the system implementation and a consistent reference to the relevant standards and regulations applicable to the subject matter. More specifically the study covers the ATEX classification of the site the safety features of each component the electrical power distribution the main safety instrumented system fire safety and the force ventilation system. The study also includes safety assessment and a section on lessons learned that could serve as guidance for future installations. In addition an extensive amount of technical data is readily available to the reader in repository (P&ID electrical diagrams etc.).

Offshore electricity production mainly by wind turbines and eventually floating PV is expected to increase renewable energy generation and their dispatchability. In this sense a significant part of this offshore electricity would be directly used for hydrogen generation. The integration of offshore energy production into the hydrogen economy is of paramount importance for both the techno-economic viability of offshore energy generation and the hydrogen economy. An analysis of this integration is presented. The analysis includes a discussion about the current state of the art of hydrogen pipelines and subsea cables as well as the storage and bunkering system that is needed on shore to deliver hydrogen and derivatives. This analysis extends the scope of most of the previous works that consider port-to-port transport while we report offshore to port. Such storage and bunkering will allow access to local and continental energy networks as well as to integrate offshore facilities for the delivery of decarbonized fuel for the maritime sector. The results of such state of the art suggest that the main options for the transport of offshore energy for the production of hydrogen and hydrogenated vectors are through direct electricity transport by subsea cables to produce hydrogen onshore or hydrogen transport by subsea pipeline. A parametric analysis of both alternatives focused on cost estimates of each infrastructure (cable/pipeline) and shipping has been carried out versus the total amount of energy to transport and distance to shore. For low capacity (100 GWh/y) an electric subsea cable is the best option. For high-capacity renewable offshore plants (TWh/y) pipelines start to be competitive for distances above approx. 750 km. Cost is highly dependent on the distance to land ranging from 35 to 200 USD/MWh.

In this paper a comparative analysis of direct operating costs between a 19-seat conventional and hydrogen-powered fuel cell aircraft is performed by developing a model to estimate direct operating costs and considering the evolution of costs over time from 2030 to 2050. However due to the technology being in its early stages of development and implementation there are still considerable uncertainties surrounding the direct operating costs of hydrogen aircraft. To address this the study considers high and low kerosene growth rates and optimistic and pessimistic development scenarios for hydrogen fuel cell aircraft while also considering the evolution of costs over time. The comparative analysis uses real flight and aircraft data for the airliner Trade Air. The results show that the use of 19-seat hydrogen fuel cell aircraft for air transportation is a viable option when compared to conventional aircraft. Additionally the study suggests potential policies and other measures that could accelerate the adoption of hydrogen fuel cell technology by considering their direct operating costs.

This paper presents a novel energy management strategy (EMS) to control a wind-hydrogen microgrid which includes a wind turbine paired with a hydrogen-based energy storage system (HESS) i.e. hydrogen production storage and re-electrification facilities and a local load. This complies with the mini-grid use case as per the IEA-HIA Task 24 Final Report where three different use cases and configurations of wind farms paired with HESS are proposed in order to promote the integration of wind energy into the grid. Hydrogen production surpluses by wind generation are stored and used to provide a demand-side management solution for energy supply to the local and contractual loads both in the grid-islanded and connected modes with corresponding different control objectives. The EMS is based on a hierarchical model predictive control (MPC) in which long-term and short-term operations are addressed. The long-term operations are managed by a high-level MPC in which power production by wind generation and load demand forecasts are considered in combination with day-ahead market participation. Accordingly the hydrogen production and re-electrification are scheduled so as to jointly track the load demand maximize the revenue through electricity market participation and minimize the HESS operating costs. Instead the management of the short-term operations is entrusted to a low-level MPC which compensates for any deviations of the actual conditions from the forecasts and refines the power production so as to address the real-time market participation and the short time-scale equipment dynamics and constraints. Both levels also take into account operation requirements and devices’ operating ranges through appropriate constraints. The mathematical modeling relies on the mixed-logic dynamic (MLD) framework so that the various logic states and corresponding continuous dynamics of the HESS are considered. This results in a mixed-integer linear program which is solved numerically. The effectiveness of the controller is analyzed by simulations which are carried out using wind forecasts and spot prices of a wind farm in center-south of Italy.

Hydrogen vehicles encompassing fuel cell electric vehicles (FCEVs) are pivotal within the UK’s energy landscape as it pursues the goal of net-zero emissions by 2050. By markedly diminishing dependence on fossil fuels FCEVs including hydrogen vehicles wield substantial influence in shaping the circular economy (CE). Their impact extends to optimizing resource utilization enabling zero-emission mobility facilitating the integration of renewable energy sources supplying adaptable energy storage solutions and interconnecting diverse sectors. The widespread adoption of hydrogen vehicles accelerates the UK’s transformative journey towards a sustainable CE. However to fully harness the benefits of this transition a robust investigation and implementation of safety measures concerning hydrogen vehicle (HV) use are indispensable. Therefore this study takes a holistic approach integrating quantitative risk assessment (QRA) and an adaptive decision-making trial and evaluation laboratory (DEMATEL) framework as pragmatic instruments. These methodologies ensure both the secure deployment and operational excellence of HVs. The findings underscore that the root causes of HV failures encompass extreme environments material defects fuel cell damage delivery system impairment and storage system deterioration. Furthermore critical driving factors for effective safety intervention revolve around cultivating a safety culture robust education/training and sound maintenance scheduling. Addressing these factors is pivotal for creating an environment conducive to mitigating safety and risk concerns. Given the intricacies of conducting comprehensive hydrogen QRAs due to the absence of specific reliability data this study dedicates attention to rectifying this gap. A sensitivity analysis encompassing a range of values is meticulously conducted to affirm the strength and reliability of our approach. This robust analysis yields precise dependable outcomes. Consequently decision-makers are equipped to discern pivotal underlying factors precipitating potential HV failures. With this discernment they can tailor safety interventions that lay the groundwork for sustainable resilient and secure HV operations. Our study navigates the intersection of HVs safety and sustainability amplifying their importance within the CE paradigm. Using the careful amalgamation of QRA and DEMATEL methodologies we chart a course towards empowering decision-makers with the insights to steer the hydrogen vehicle domain to safer horizons while ushering in an era of transformative eco-conscious mobility.

A transition towards zero-emission fuels is required in the mobility sector in order to reach the climate goals. Here (green) renewable hydrogen for use in fuel cells will play an important role especially for heavy duty applications such as trucks. However there are still challenges to overcome regarding efficient storage infrastructure integration and optimization of the refuelling process. A key aspect is to reduce the refuelling duration as much as possible while staying below the maximum allowed temperature of 85 C. Experimental tests for the refuelling of a 320 l type III tank were conducted at different operating conditions and the tank gas temperature measured at the front and back ends. The results indicate a strongly inhomogeneous temperature field where measuring and verifying the actual maximum temperatures proves difficult. Furthermore a simulation approach is provided to calculate the average tank gas temperature at the end of the refuelling process.

In this paper a computational fluid dynamics (CFD) model was established and verified on the basis of experimental results and then the effect of hydrogenation addition on combustion and emission characteristics of a diesel–hydrogen dual-fuel engine fueled with hydrogenation addition (0% 5% and 10%) under different hydrogenation energy shares (HESs) and compression ratios (CRs) were investigated using CONVERGE3.0 software. And this work assumed that the hydrogen and air were premixed uniformly. The correctness of the simulation model was verified by experimental data. The values of HES are in the range of 0% 5% 10% and 15%. And the values of CR are in the range of 14 16 18 and 20. The results of this study showed that the addition of hydrogen to diesel fuel has a significant effect on the combustion characteristics and the emission characteristics of diesel engines. When the HES was 15% the in-cylinder pressure increased by 10.54%. The in-cylinder temperature increased by 15.11%. When the CR was 20 the in-cylinder pressure and the in-cylinder temperature increased by 66.10% and 13.09% respectively. In all cases HC CO CO2 and soot emissions decreased as the HES increased. But NOx emission increased.

The economic operation of the integrated energy system faces the problems of coupling between energy production and conversion equipment in the system and the imbalance of various energy demands. Therefore taking system safety as the constraint and minimum economic cost as the objective function including fuel cost operation and maintenance cost this paper proposes the operation dispatching model of the integrated energy system based on hydrogen fuel cell (HFC) including HFC photovoltaic wind turbine electric boiler electric chiller absorption chiller electric energy storage and thermal energy storage equipment. On this basis a distributionally robust optimization (DRO) model is introduced to deal with the uncertainty of wind power and photovoltaic output. In the distributionally robust optimization model Kullback–Leibler (KL) divergence is used to construct an ambiguity set which is mainly used to describe the prediction errors of renewable energy output. Finally the DRO economic dispatching model of the HFC integrated energy system (HFCIES) is established. Besides based on the same load scenario the economic benefits of hybrid energy storage equipment are discussed. The dispatching results show that compared with the scenario of only electric energy storage and only thermal energy storage the economic cost of the scenario of hybrid electric and thermal storage can be reduced by 3.92% and 7.55% respectively and the use of energy supply equipment can be reduced and the stability of the energy storage equipment can be improved.

Storing energy in hydrogen deposits balances the operation of energy systems and is an effective tool in the process of energy transformation towards achieving Sustainable Development Goals. To assess the validity of its use as an alternative renewable energy carrier in dispersed energy systems of hybrid configuration a comprehensive review of scientific literature was conducted in this study based on bibliometric analysis. The bibliographic database used in the study was the international Web of Science database. This review contributes to a better understanding of the characteristics of the selected research area. The evolution of research trends implemented in the design of energy systems associated with hydrogen technologies is revealed clearly indicating that it is a developing field. In recent years there has been an increase in the number of publications although the territorial range of research (mainly simulation) conducted in the domain does not include areas with the most favourable infrastructural conditions. The analysis reveals weak cooperation between South American African East Asian and Oceanic countries. In the light of earlier thematically similar literature reviews several research gaps are also identified and proposals for future research are presented. They concern in particular the parallel implementation and optimization of the operation of hydrogen (HRES—Hybrid Renewable Energy System and HESS—Hybrid Energy Storage System) solutions in terms of economics ecology lifespan and work efficiency as well as their feasibility analysis. With the support of other researchers and those involved in the subject matter this review may contribute to the further development of hybrid hydrogen systems in terms of increasing competitiveness and promoting the implementation of these technologies.

The importance of electric vehicle charging stations (EVCS) is increasing as electric vehicles (EV) become more widely used. EVCS with multiple low-carbon energy sources can promote sustainable energy development. This paper presents an optimization methodology for direct energy exchange between multi-geographic dispersed EVCSs in London UK. The charging stations (CSs) incorporate solar panels hydrogen battery energy storage systems and grids to support their operations. EVs are used to allow the energy exchange of charging stations. The objective function of the solar-hydrogen-battery storage electric vehicle charging station (SHS-EVCS) includes the minimization of both capital and operation and maintenance (O&M) costs as well as the reduction in greenhouse gas emissions. The system constraints encompass the power output limits of individual components and the need to maintain a power balance between the SHS-EVCSs and the EV charging demand. To evaluate and compare the proposed SHS-EVCSs two multi-objective optimization algorithms namely the Non-dominated Sorting Genetic Algorithm (NSGA-II) and the Multi-objective Evolutionary Algorithm Based on Decomposition (MOEA/D) are employed. The findings indicate that NSGA-II outperforms MOEA/D in terms of achieving higher-quality solutions. During the optimization process various factors are considered including the sizing of solar panels and hydrogen storage tanks the capacity of electric vehicle chargers and the volume of energy exchanged between the two stations. The application of the optimized SHS-EVCSs results in substantial cost savings thereby emphasizing the practical benefits of the proposed approach.

We conduct a techno-economic assessment of two low-emissions steel production technologies and evaluate their deployment in emissions mitigation scenarios utilizing the MIT Economic Projection and Policy Analysis (EPPA) model. Specifically we assess direct reduced iron-electric arc furnace with carbon capture and storage (DRI-EAF with CCS) and H2-based direct reduced iron-electric arc furnace (H2 DRI-EAF) which utilizes low carbon hydrogen to reduce CO2 emissions. Our techno-economic analysis based on the current state of technologies found that DRI-EAF with CCS increased costs ~7% relative to the conventional steel technology. H2 DRI-EAF increased costs by ~18% when utilizing Blue hydrogen and ~79% when using Green hydrogen. The exact pathways for hydrogen production in different world regions including the extent of CCS and hydrogen deployment in steelmaking are highly speculative at this point. In illustrative scenarios using EPPA we find that using base cost assumptions switching from BF-BOF to DRI-EAF or scrap EAF can provide significant emissions mitigation within steelmaking. With further reductions in the cost of advanced steelmaking we find a greater role for DRI-EAF with CCS whereas reductions in both the cost of advanced steelmaking and hydrogen production lead to a greater role for H2 DRI-EAF. Our findings can be used to help decision-makers assess various decarbonization options and design economically efficient pathways to reduce emissions in the steel industry. Our cost evaluation can also be used to inform other energy-economic and integrated assessment models designed to provide insights about future decarbonization pathways.

Fuel cell hybrid electric vehicles have the advantages of zero emission high efficiency and fast refuelling etc. and are one of the key directions for vehicle development. The energy management problem of fuel cell hybrid electric vehicles is the key technology for power distribution. The traditional power following strategy has the advantage of a real-time operation but the power correction is usually based only on the state of charge of a lithium battery which causes the operating point of the fuel cell to be in the region of a low efficiency. To solve this problem this paper proposes a hybrid power-following-fuzzy control strategy where a fuzzy logic control strategy is used to optimise the correction module based on the power following strategy which regulates the state of charge while correcting the output power of the fuel cell towards the efficient operating point. The results of the joint simulation with Matlab + Advisor under the Globally Harmonised Light Vehicle Test Cycle Conditions show that the proposed strategy still ensures the advantages of real-time energy management and for the hydrogen fuel cell the hydrogen consumption is reduced by 13.5% and 4.1% compared with the power following strategy and the fuzzy logic control strategy and the average output power variability is reduced by 14.6% and 5.1% respectively which is important for improving the economy of the whole vehicle and prolonging the lifetime of fuel cell.

Turquoise hydrogen from natural gas pyrolysis has recently emerged as a promising alternative for low-carbon hydrogen production with a high-value pure carbon by-product. However the implications of this technology on the broader energy system are not well understood at present. To close this literature gap this study presents an assessment of the integration of natural gas pyrolysis into a simplified European energy system. The energy system model minimizes the cost by optimizing investment and hourly dispatch of a broad range of electricity and fuel production transmission and storage technologies as well as imports/exports on the global market. Norway is included as a major natural gas producer and Germany as a major energy importer. Results reveal that pyrolysis is economically attractive at modest market shares where the carbon by-product can be sold into highvalue markets for 400 €/ton. However pyrolysis-dominated scenarios that employ methane as a hydrogen carrier also hold promise as they facilitate deep decarbonization without the need for vast expansions of international electricity hydrogen and CO2 transmission networks. The simplicity and security benefits of such pyrolysis-led decarbonization pathways justify the modest 11 % cost premium involved for an energy system where natural gas is the only energy trade vector. In conclusion there is a strong case for turquoise hydrogen in future energy systems and further efforts for commercialization of natural gas pyrolysis are recommended.

This work undertakes a techno‑economic comparative analysis of the design of photo‑ voltaic panel/wind turbine/electrolyzer‑H2 tank–fuel cell/electrolyzer‑H2 tank (configuration 1) and photovoltaic panel/wind turbine/battery/electrolyzer‑H2 tank (configuration 2) to supply electricity to a simulated house and a hydrogen‑powered vehicle on Jeju Island. The aim is to find a system that will make optimum use of the excess energy produced by renewable energies to power the hydrogen vehicle while guaranteeing the reliability and cost‑effectiveness of the entire system. In addition to evaluating the Loss of Power Supply Probability (LPSP) and the Levelized Cost of Energy (LCOE) the search for achieving that objective leads to the evaluation of two new performance indicators: Loss of Hydrogen Supply Probability (LHSP) and Levelized Cost of Hydrogen (LCOH). After anal‑ ysis for 0 < LPSP < 1 and 0 < LHSP < 1 used as the constraints in a multi‑objective genetic algorithm configuration 1 turns out to be the most efficient loads feeder with an LCOE of 0.3322 USD/kWh an LPSP of 0% concerning the simulated house load an LCOH of 11.5671 USD/kg for a 5 kg hydrogen storage and an LHSP of 0.0043% regarding the hydrogen vehicle load.

Green hydrogen generation driven by solar-wind hybrid power is a key strategy for obtaining the low-carbon energy while by considering the fluctuation natures of solar-wind energy resource the system capacity configuration of power generation hydrogen production and essential storage devices need to be comprehensively optimized. In this work a solar-wind hybrid green hydrogen production system is developed by combining the hydrogen storage equipment with the power grid the coordinated operation strategy of solar-wind hybrid hydrogen production is proposed furthermore the NSGA-III algorithm is used to optimize the system capacity configuration with the comprehensive performance criteria of economy environment and energy efficiency. Through the implemented case study with the hydrogen production capacity of 20000 tons/year the abandoned energy power rate will be reduced to 3.32% with the electrolytic cell average load factor of 64.77% and the system achieves the remarkable carbon emission reduction. In addition with the advantage of connect to the power grid the generated surplus solar/wind power can be readily transmitted with addition income when the sale price of produced hydrogen is suggested to 27.80 CNY/kgH2 the internal rate of return of the system reaches to 8% which present the reasonable economic potential. The research provides technical and methodological suggestions and guidance for the development of solar-wind hybrid hydrogen production schemes with favorable comprehensive performance.

Public transport plays a prominent role with respect to mitigating transport-related environmental effects by improving passenger transport efficiency and the quality of life in cities. Batteries and fuel cells are at the forefront of the technological shift to zero-emission powertrains. Within the scope of the German-funded project BIC H2 corresponding systems analysis research focuses on the market introduction of fuel cell–electric buses in the Rhine–Ruhr Metropolitan Region through 2035. This study presents the related methods and major outcomes of this techno-economic research which spans spatially-resolved hydrogen demand modeling of all relevant sectors to hydrogen refueling stations and upstream infrastructure modeling to scenario-based analyses. The latter builds upon an empirical study supporting the development of the Hydrogen Roadmap of the State of North Rhine–Westphalia (NRW). Our results show that the demand in NRW alone is expected to account for one third of total German hydrogen use. Hydrogen bus refueling could substantially support market introduction during its early phases. In the long term however hydrogen demand in industry is significantly higher compared to that in the transport sector. Furthermore spatial analysis identifies regions with pronounced hydrogen demands that could therefore be candidates for initial infrastructure investments. With the Cologne area showing the highest hydrogen demand levels such regions can offer particularly high infrastructure utilization e.g. for bus refueling. On the infrastructure side trailers for transporting gaseous hydrogen to refueling stations are the most favorable option through 2035. Pipelines would be the preferred solution soon after 2035 due to increased hydrogen demand. If effectively deployed converted natural gas pipelines would be the most cost-effective option even earlier.

This study proposed a deep reinforcement learning-based energy management strategy (DRL-EMS) that can be applied to a hybrid electric ship propulsion system (HSPS) integrating liquid hydrogen (LH2 ) fuel gas supply system (FGSS) proton-exchange membrane fuel cell (PEMFC) and lithium-ion battery systems. This study analyzed the optimized performance of the DRL-EMS and the operational strategy of the LH2 -HSPS. To train the proposed DRL-EMS a reward function was defined based on fuel consumption and degradation of power sources during operation. Fuel consumption for ship propulsion was estimated with the power for balance of plant (BOP) of the LH2 FGSS and PEMFC system. DRL-EMS demonstrated superior global and real-time optimality compared to benchmark algorithms namely dynamic programming (DP) and sequential quadratic programming (SQP)-based EMS. For various operation cases not used in training DRL-EMS resulted in 0.7% to 9.2% higher operating expenditure compared to DP-EMS. Additionally DRL-EMS was trained to operate 60% of the total operation time in the maximum efficiency range of the PEMFC system. Different hydrogen fuel costs did not affect the optimized operational strategy although the operating expenditure (OPEX) was dependent on the hydrogen fuel cost. Different capacities of the battery system did not considerably change the OPEX.

This work addresses the energy efficiency of hydrogen refueling stations (HRS) using a first principles model and optimal control methods to find minimal entropy production operating paths. The HRS model shows good agreement with experimental data achieving maximum state of charge and temperature discrepancies of 1 and 7% respectively. Model solution and optimization is achieved at a relatively low computational time (40 s) when compared to models of the same degree of accuracy. The entropy production mapping indicates the flow control valve as the main source of irreversibility accounting for 85% of the total entropy production in the process. The minimal entropy production refueling path achieves energy savings from 20 to 27% with respect to the SAE J2601 protocol depending on the ambient temperature. Finally the proposed method under nearreversible refueling conditions shows a theoretical reduction of 43% in the energy demand with respect to the SAE J2601 protocol.

In terms of energy generation and consumption ships are autonomous isolated systems with power demands varying according to the type of ship: passenger or commercial. The power supply in modern ships is based on thermal engines-generators which use fossil fuels marine diesel oil (MDO) and liquefied natural gas (LNG). The continuous operation of thermal engines on ships during cruises results in increased emissions of polluting gases mainly CO/CO2 . The combination of renewable energy sources (REs) and triple-fuel diesel engines (TFDEs) can reduce CO/CO2 emissions resulting in a “greener” interaction between ships and the ecosystem. This work presents a new control method for balancing the power generation and the load demands of a ship equipped with TFDEs fuel cells (FCs) and REs based on a real and accurate model of a super-tanker and simulation of its operation in real cruise conditions. The new TFDE technology engines are capable of using different fuels (marine diesel oil heavy fuel oil and liquified natural gas) producing the power required for ship operation as well as using compositions of other fuels based on diesel aiming to reduce the polluting gases produced. The energy management system (EMS) of a ship is designed and implemented in the structure of a finite state machine (FSM) using the logical design of transitions from state to state. The results demonstrate that further reductions in fossil fuel consumption as well as CO2 emissions are possible if ship power generation is combined with FC units that consume hydrogen as fuel. The hydrogen is produced locally on the ship through electrolysis using the electric power generated by the on-board renewable energy sources (REs) using photovoltaic systems (PVs) and wind energy conversion turbines (WECs).

The transportation sector plays an important role in the current effort towards the control of global warming. Against this backdrop electrification is currently attracting attention as the life cycle environmental performance of different powertrain technologies is critically assessed. In this study a life cycle analysis of the public transportation buses was performed. The scope of the analysis is to compare the energy and global warming performances of the different powertrain technologies in the city fleet: diesel full electric and hydrogen buses. Real world monitored data were used in the analysis for the energy consumptions of the buses and to produce hydrogen in Bolzano. Compared to the traditional diesel buses the electric vehicles showed a 43% reduction of the non-renewable primary energy demand and a 33% of the global warming potential even in the worst consequential scenario considered. The switch to hydrogen buses leads to very different environmental figures: from very positive if it contributes to a further penetration of renewable electricity to hardly any difference if hydrogen from steam-methane reforming is used to clearly negative ones (approximately doubling the impacts) if a predominantly fossil electricity mix is used in the electrolysis.

This manuscript presents a thorough review of unitized regenerative fuel cells (URFCs) and their importance in Remote Area Power Supply (RAPS). In RAPS systems that utilize solar and hydrogen power which typically include photovoltaic modules a proton exchange membrane (PEM) electrolyzer hydrogen gas storage and PEM fuel cells the cost of these systems is currently higher compared to conventional RAPS systems that employ diesel generators or batteries. URFCs offer a potential solution to reduce the expenses of solar hydrogen renewable energy systems in RAPS by combining the functionalities of the electrolyzer and fuel cell into a single unit thereby eliminating the need to purchase separate and costly electrolyzer and fuel cell units. URFCs are particularly well-suited for RAPS applications because the electrolyzer and fuel cell do not need to operate simultaneously. In electrolyzer mode URFCs function similarly to stand-alone electrolyzers. However in fuel cell mode the performance of URFCs is inferior to that of stand-alone fuel cells. The presented review summarizes the past present and future of URFCs with details on the operating modes of URFCs limitations and technical challenges and applications. Solar hydrogen renewable energy applications in RAPS and challenges facing solar hydrogen renewable energy in the RAPS is discussed in detail.

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.

The latest International Maritime Organization strategies aim to reduce 70% of the CO2 emissions and 50% of the Greenhouse Gas (GHG) emissions from maritime activities by 2050 compared to 2008 levels. The EU has set up goals to reduce GHG emissions by at least 55% by 2030 compared to 1990 and achieve net-zero GHG emissions by 2050. The UK aims to achieve more than 68% GHG emission reduction by 2030 and net-zero GHG emissions by 2050. There are many solutions under development to tackle the challenge of meeting the latest decarbonization strategies from the IMO EU and UK among which are hydrogen powered marine vessels. This paper presents a life cycle analysis study for hydrogen fuelled vessels by evaluating their performance in terms of environmental friendliness and economic feasibility. The LCA study will consider the gas emissions and costs during the life stages of the ships including the construction operation maintenance and recycling phases of the selected vessels. The results of the comparisons with the conventional version of the ships (driven by diesel generators) demonstrate the benefits of using hydrogen for marine transportation: over 80% emission reduction and around 60% life cycle cost savings. A sensitivity analysis shows that the prices of fuels and carbon credits can affect the life cycle cost and recommendations for low H2 price and high carbon credit in the future are provided to attract the industry to adopt the new fuel.

Feedstock-to-fuel conversion or “Fuel Production” is a major contributor to greenhouse gas (GHG) emissions in life cycle assessment (LCA) of sustainable aviation fuels (SAF) from wastes. Here we construct and demonstrate an original mass and energy conserved chemically rigorous LCA methodology for the production of Hydroprocessed Esters and Fatty Acids-Synthetic Paraffinic Kerosene (HEFA-SPK) from Used Cooking Oil (UCO). This study proposes and demonstrates the use of; (i) the chemical composition of the UCO (ii) the ASTM properties of HEFA-SPK and (iii) the elemental mass and energy conserved reaction mechanism which converts one to the other as physical constraints for the specific LCA of any UCO derived HEFA-SPK. With application of these constraints the emissions embodied in UCO HEFA-SPK Fuel Production is found to range from 4.2 to 15.7 gCO2e/MJSAF depending on the renewability of the energy and hydrogen utilized. Imposition of (i)-(iii) as modelling constraints derives a HEFA-SPK yield of 49 mass% a priori. This finding aligns with experimental literature but brings attention to the higher yield estimations of 70–81% observed in current LCA tools. We show that this impacts the end LCA significantly as it adjusts allocation of emissions. A replication study of CORSIA’s (10.5 gCO2e/MJSAF) default core LCA value for Fuel Production quantifies the increase at +5.3 gCO2e/MJSAF or 15.8 gCO2e/MJSAF as total for Fuel Production. As the embodied emissions are significantly dependent on the specifics of the scenario assessed we highlight reporting a definitive GHG intensity for any UCO derived HEFA-SPK as generic will be inaccurate to an extent.

In the context of “dual carbon” restrictions on carbon emissions have aĴracted widespread aĴention from researchers. In order to solve the issue of the insufficient exploration of the synergistic emission reduction effects of various low-carbon policies and technologies applied to multiple microgrids we propose a multi-microgrid electricity cooperation optimization scheduling strategy based on stepped carbon trading a hydrogen-doped natural gas system and P2G–CCS coupled operation. Firstly a multi-energy microgrid model is developed coupled with hydrogendoped natural gas system and P2G–CCS and then carbon trading and a carbon emission restriction mechanism are introduced. Based on this a model for multi-microgrid electricity cooperation is established. Secondly design optimization strategies for solving the model are divided into the dayahead stage and the intraday stage. In the day-ahead stage an improved alternating direction multiplier method is used to distribute the model to minimize the cooperative costs of multiple microgrids. In the intraday stage based on the day-ahead scheduling results an intraday scheduling model is established and a rolling optimization strategy to adjust the output of microgrid equipment and energy purchases is adopted which reduces the impact of uncertainties in new energy output and load forecasting and improves the economic and low-carbon operation of multiple microgrids. SeĴing up different scenarios for experimental validation demonstrates the effectiveness of the introduced low-carbon policies and technologies as well as the effectiveness of their synergistic interaction

Efficiently predicting and understanding refuelling patterns in the context of HFVs is paramount for optimising fuelling processes infrastructure planning and facilitating vehicle operation. This study evaluates several supervised machine learning methodologies for predicting the refuelling behaviour of HFVs. The LightGBM model emerged as the most effective predictive model due to its ability to handle time series and seasonal data. The selected model integrates various input variables encompassing refuelling metrics day of the week and weather conditions (e.g. temperature precipitation) to capture intricate patterns and relationships within the data set. Empirical testing and validation against real-world refuelling data underscore the efficacy of the LightGBM model demonstrating a minimal deviation from actual data given limited data and thereby showcasing its potential to offer valuable insights to fuelling station operators vehicle manufacturers and policymakers. Overall this study highlights the potential of sustainable predictive modelling for optimising fuelling processes infrastructure planning and facilitating vehicle operation in the context of HFVs.

An integrated system is studied to supply green hydrogen feedstock for ammonia production in the Netherlands. The system is modeled to compare wind and solar resources when coupled to Alkaline Electrolysis (AEL) and Proton Exchange Membrane Electrolysis (PEMEL) technologies with a compressed hydrogen storage system. The nominal installed capacity of the electrolysis plant is around 2.3 GW with the most suitable energy source offshore wind and the preferred storage technology pressurized tubes. For Alkaline Electrolysis and Proton Exchange Membrane Electrolysis technologies the levelized cost of hydrogen is 5.30 V/kg H2 and 6.03 V/kg H2 respectively.

This paper presents an economic impact analysis and carbon footprint study of a hydrogenbased microgrid. The economic impact is evaluated with respect to investment costs operation and maintenance (O&M) costs as well as savings taking into account two different energy management strategies (EMSs): a hydrogen-based priority strategy and a battery-based priority strategy. The research was carried out in a real microgrid located at the University of Huelva in southwestern Spain. The results (which can be extrapolated to microgrids with a similar architecture) show that although both strategies have the same initial investment costs (EUR 52339.78) at the end of the microgrid lifespan the hydrogen-based strategy requires higher replacement costs (EUR 74177.4 vs. 17537.88) and operation and maintenance costs (EUR 35254.03 vs. 34877.08) however it provides better annual savings (EUR 36753.05 vs. 36282.58) and a lower carbon footprint (98.15% vs. 95.73% CO2 savings) than the battery-based strategy. Furthermore in a scenario where CO2 emission prices are increasing the hydrogen-based strategy will bring even higher annual cost savings in the coming years.

Because the new energy is intermittent and uncertain it has an influence on the system’s output power stability. A hydrogen energy storage system is added to the system to create a wind light and hydrogen integrated energy system which increases the utilization rate of renewable energy while encouraging the consumption of renewable energy and lowering the rate of abandoning wind and light. Considering the system’s comprehensive operation cost economy power fluctuation and power shortage as the goal considering the relationship between power generation and load assigning charging and discharging commands to storage batteries and hydrogen energy storage and constructing a model for optimal capacity allocation of wind–hydrogen microgrid system. The optimal configuration model of the wind solar and hydrogen microgrid system capacity is constructed. A particle swarm optimization with dynamic adjustment of inertial weight (IDW-PSO) is proposed to solve the optimal allocation scheme of the model in order to achieve the optimal allocation of energy storage capacity in a wind–hydrogen storage microgrid. Finally a microgrid system in Beijing is taken as an example for simulation and solution and the results demonstrate that the proposed approach has the characteristics to optimize the economy and improve the capacity of renewable energy consumption realize the inhibition of the fluctuations of power reduce system power shortage and accelerate the convergence speed.

Renewable energy solutions play a crucial role in addressing the growing energy demands while mitigating environmental concerns. This study examines the techno-economic viability and sensitivity of utilizing solar photovoltaic/polymer electrolyte membrane (PEM) fuel cells (FCs) to meet specific power demands in NEOM Saudi Arabia. The novelty of this study lies in its innovative approach to analyzing and optimizing PV/PEMFC systems aiming to highlight their economic feasibility and promote sustainable development in the region. The analysis focuses on determining the optimal size of the PV/PEMFC system based on two critical criteria: minimum cost of energy (COE) and minimum net present cost (NPC). The study considers PEMFCs with power ratings of 30 kW 40 kW and 50 kW along with four PV panel options: Jinko Solar Powerwave Tindo Karra and Trina Solar. The outcomes show that the 30 kW PEMFC and the 201 kW Trina Solar TSM-430NEG9R.28 are the most favorable choices for the case study. Under these optimal conditions the study reveals the lowest values for NPC at USD 703194 and COE at USD 0.498 per kilowatt-hour. The levelized cost of hydrogen falls within the range of USD 15.9 to 23.4 per kilogram. Furthermore replacing the 30 kW Trina solar panel with a 50 kW Tindo PV module results in a cost reduction of 32%. The findings emphasize the criticality of choosing optimal system configurations to attain favorable economic outcomes thereby facilitating the adoption and utilization of renewable energy sources in the region. In conclusion this study stands out for its pioneering and thorough analysis and optimization of PV/PEMFC systems providing valuable insights for sustainable energy planning in NEOM Saudi Arabia.

The integration of an increasing share of Renewable Energy Sources (RES) requires the availability of suitable energy storage systems to improve the grid flexibility and Compressed Air Energy Storage (CAES) systems could be a promising option. In this study a CO2 -free Diabatic CAES system is proposed and analyzed. The plant configuration is derived from a down-scaled version of the McIntosh Diabatic CAES plant where the natural gas is replaced with green hydrogen produced on site by a Proton Exchange Membrane electrolyzer powered by a photovoltaic power plant. In this study the components of the hydrogen production system are sized to maximize the self-consumption share of PV energy generation and the effect of the design parameters on the H2 -CAES plant performance are analyzed on a yearly basis. Moreover a comparison between the use of natural gas and hydrogen in terms of energy consumption and CO2 emissions is discussed. The results show that the proposed hydrogen fueled CAES can effectively match the generation profile and the yearly production of the natural gas fueled plant by using all the PV energy production while producing zero CO2 emissions.

In recent years several approaches and pathways have been discussed to decarbonise the transport sector; however any effort to reduce emissions might be complex due to specific socio-economic and technical characteristics of different regions. In Mexico the transport sector is the highest energy consumer representing 38.9% of the national final energy demand with gasoline and diesel representing 90% of the sector´s total fuel consumption. Energy systems models are powerful tools to obtain insights into decarbonisation pathways to understand costs emissions and rate of deployment that could serve for energy policy development. This paper focuses on the modelling of the current Mexican transport system using the MUSE-MX multi-regional model with the aim to project a decarbonisation pathway through two different scenarios. The first approach being business as usual (BAU) which aims to analyse current policies implementation and the second being a goal of net zero carbon emissions by 2050. Under the considered net zero scenario results show potential deployment of hydrogen-based transport technologies especially for subsectors such as lorries (100% H2 by 2050) and freight train (25% H2 by 2050) while cars and buses tend to full electrification by 2050.

The current political scenario and the concerns for global warming have pushed very harsh regulations on conventional propulsion systems based on the use of fossil fuels. New technologies are being promoted but their current technological status needs further research and development for them to become a competitive substitute for the ever-present internal combustion engine. Hydrogen-fueled internal combustion engines have demonstrated the potential of being a fast way to reach full decarbonization of the transport sector but they still have to face some limitations in terms of the operating range of the engine. For this reason the present work evaluates the potential of reaching full load operation on a conventional diesel engine assuming the minimum modifications required to make it work under H2 combustion. This study shows the methodology through which the combustion model was developed and then used to evaluate a multi-cylinder engine representative of the medium to high duty transport sector. The evaluation included different strategies of dilution to control the combustion performance and the results show that the utilization of EGR brings different benefits to engine operation in terms of efficiency improvement and emissions reduction. Nonetheless the requisites defined for the needed turbocharging system are harsher than expected and result in a potential non-conventional technical solution.

In the global content regarding the impact on the environmental of the gases emissions resulted from the fossil fuels combustion aspect discussed on the 2015 Paris Climate Conference contribute to the necessity of searching of alternative energy from durable and renewable resources. The purpose of the paper is the use of hydrogen fuelling at truck diesel engine in order to improves engine efficiency and pollutant performance hydrogen being injected into the inlet manifold. Experimental results show better energetic and pollution performance of the dual fuelled engine due to the improvement of the combustion process and reduction of carbon content.

The power and transport sectors are responsible for significant emissions of greenhouse gases. Therefore it is imperative that substantial efforts are directed towards the decarbonisation of these industries. This study establishes a combined-solar-wind system's economic and technical practicality for producing hydrogen for an onsite hydrogen refuelling station (HRS) and electricity to meet peak demand. To minimise the levelised cost of electricity and maximise the system's reliability at different commercial locations in South Africa the dual-objective optimisation sizing is carried out using Mixed Integer Quadratic Constrained Programming (MICQP) model and was executed with an Advanced Multi-dimensional Modelling System (AIMMS) [61] [62]. The levelised costs of electricity and hydrogen at Johannesburg Pretoria and Cape Town for 2 MW grid export benchmark are 74.2 $/MWh/5.85 $/kg 76.3 $/MWh/5.97 $/kg and 50 $/MWh/4.45 $/kg respectively. The CO₂ equivalent emissions (tonnes) are 54000 55800 59000 and the corresponding carbon taxes ($) avoided for the locations are 432100 446200 and 472000 for Johannesburg Pretoria and Cape Town respectively. The results of the framework show that it can be adopted as a viable and fossil-free replacement for conventional peaking generators.

A direct drive wave power generation system (DDWPGS) has the advantages of a simple structure and easy deployment and is the first choice to provide electricity for islands and operation platforms in the deep sea. However due to the off-grid the source and load cannot be matched so accommodation is an important issue. Hydrogen storage is the optimal choice for offshore wave energy accommodation. Therefore aiming at the source-load mismatch problem of the DDWPGS an electric-hydrogen hybrid energy storage system (HESS) for the DDWPGS is designed in this paper. Based on the characteristics of the devices in the electric-hydrogen HESS a new dynamic power allocation strategy and its control strategy are proposed. Firstly empirical mode decomposition (EMD) is utilized to allocate the power fluctuations that need to be stabilized. Secondly with the state of charge (SOC) of the battery and the operating characteristics of the alkaline electrolyzer being considered the power assignments of the battery and the electrolyzer are determined using the rule-based method. In addition model predictive control (MPC) with good tracking performance is used to adjust the output power of the battery and electrolyzer. Finally the supercapacitor (SC) is controlled to maintain the DC bus voltage while also balancing the system’s power. A simulation was established to verify the feasibility of the designed system. The results show that the electric-hydrogen HESS can stabilize the power fluctuations dynamically when the DDWPGS captures instantaneous power. Moreover its control strategy can not only reduce the start-stop times of the alkaline electrolyzer but also help the energy storage devices to maintain a good state and extend the service life.

This paper addresses the topic of the conceptual design of a regional aircraft with hybrid electric propulsion based on hydrogen fuel cells. It aims at providing an optimization-based method to design a hybrid propulsive system comprising two power sources (jet fuel and hydrogen) for the generation of the required propulsive power and at studying the impact of fuel cell technologies on the aircraft performances. Indeed by performing optimizations for two hybrid propulsive systems using either low temperature or high temperature Proton-exchange membrane fuel cells this study provides a preliminary assessment of the impact of the fuel cell operating temperature on the system design and the overall aircraft performance. First this paper gives a description of the baseline turboprop regional aircraft with a focus on its high speed and low speed flight performances which will serve as requirements for the design of the hybrid aircraft. Then the hybrid electric architecture and the sizing models of the propulsion system are presented. Finally optimizations are performed to design two parallel hybrid propulsive systems based on different fuel cells technologies and aimed at minimizing the block fuel per passenger over a mission of 200 nm. Results show how the proposed methodology and models lead to design two propulsive systems capable of reducing the fuel consumption per passenger by more than 30% compared to the baseline aircraft. The study also shows that the choice of fuel cell operating temperature has a first-order impact on the total mass of the propulsive system due to the higher cooling requirement of the low temperature fuel cells.

This work evaluates the effectiveness of chemical-based solutions for storing large amounts of renewable electricity. Four “Power-to-X-to-Power” pathways are examined comprising hydrogen methane methanol and ammonia as energy carriers. The pathways are assessed using a model scenario where they are produced with electricity from an onshore wind farm stored in suitable facilities and then reconverted to electricity to meet the energy demand of a chemical site. An energy management and storage capacity estimation tool is used to calculate the annual load coverage resulting from each pathway. All four pathways offer a significant increase in load coverage compared to a scenario without storage solution (56.19%). The hydrogen-based pathway has the highest load coverage (71.88%) and round-trip efficiency (36.93%) followed by the ammonia-based (69.62% 31.37%) methanol-based (67.85% 27.00%) and methane-based (67.64% 26.47% respectively) pathways. The substantially larger storage capacity required for gaseous energy carriers to ensure a steady supply to the consumer could be a decisive factor. The hydrogen pathway requires a storage volume up to 10.93 times larger than ammonia and 16.87 times larger than methanol. Notably ammonia and methanol whose load coverages are only 2.26 and 4.03 percentage points lower than that of hydrogen offer the possibility of implementing site-specific storage solutions avoiding potential bottlenecks due to limited pipeline and cavern capacities.

Interest in hydrogen-powered rail vehicles has gradually increased worldwide over recent decades due to the global pressure on reduction in greenhouse gas emissions technology availability and multiple options of power supply. In the past research and development have been primarily focusing on light rail and regional trains but the interest in hydrogen-powered freight and heavy haul trains is also growing. The review shows that some technical feasibility has been demonstrated from the research and experiments on proof-of-concept designs. Several rail vehicles powered by hydrogen either are currently operating or are the subject of experimental programmes. The paper identifies that fuel cell technology is well developed and has obvious application in providing electrical traction power while hydrogen combustion in traditional IC engines and gas turbines is not yet well developed. The need for on-board energy storage is discussed along with the benefits of energy management and control systems.

The importance of new alternative fuels has assumed great relevance in the last decades to face the issues of global warming and pollutant emissions from energy production. The scientific community is responsible for developing solutions to achieve the necessary environmental restriction policies. In this context ammonia appears as a potential fuel candidate and energy vector that may solve the technological difficulties of using hydrogen (H2 ) directly in internal combustion engines. Its high hydrogen content per unit mass higher energy density than liquid hydrogen well-developed infrastructure and experience in handling and storage make it suitable to be implemented as a long-term solution. In this work a virtual engine model was developed to perform prospective simulations of different operating conditions using ammonia and H2 -enriched ammonia as fuel in a spark-ignition (SI) engine integrating a chemical kinetics model and empirical correlations for combustion prediction. In addition specific conditions were evaluated to consider and to understand the governing parameters of ammonia combustion using computational fluid dynamics (CFD) simulations. Results revealed similar thermal efficiency than methane fuel with considerable improvements after appropriate H2 - enrichment. Moreover increasing the intake temperature and the turbulence intensity inside the cylinder evinced significant reductions in combustion duration. Finally higher compression ratios ensure efficiency gains with no evidence of abnormal combustion (knocking) even at high compression ratios (above 16:1) and low engine speeds (800 rpm). Numerical simulations showed the direct influence of the flame front surface area and the turbulent combustion velocity on efficiency reflecting the need for optimizing the SI engines design paradigm for ammonia applications.

Ensuring the energy transition in order to decrease CO2 and volatile organic compounds emissions and improve the efficiency of energy processes requires the development of advanced materials and technologies for the electrical energy sector. The article reviews superconducting materials functional nanomaterials used in the power industry mainly due to their magnetic electrical optical and dielectric properties and the thin layers of amorphous carbon nitride which properties make them an important material from the point of view of environmental protection optoelectronic photovoltaic and energy storage. The superconductivity-based technologies material processing and thermal and nonthermal plasma generation have been reviewed as technologies that can be a solution to chosen problems in the electrical energy sector and environment. The study explains directly both—the basics and application potential of low and high-temperature superconductors as well as peculiarities of the related manufacturing technologies for Roebel cables 1G and 2G HTS tapes and superconductor coil systems. Among the superconducting materials particular attention was paid to the magnesium di-boride MgB2 and its potential applications in the power industry. The benefits of the use of carbon films with amorphous structures in electronics sensing technologies solar cells FETs and memory devices were discussed. The article provides the information about most interesting from the R&D point of view groups of materials for PV applications. It summarises the advantages and disadvantages of their use regarding commercial requirements such as efficiency lifetime light absorption impact on the environment costs of production and weather dependency. Silicon processing inkjet printing vacuum deposition and evaporation technologies that allow obtaining improved and strengthened materials for solar cell manufacturing are also described. In the case of the widely developed plasma generation field waste-to-hydrogen technology including both thermal and non-thermal plasma techniques has been discussed. The review aims to draw attention to the problems faced by the modern power industry and to encourage research in this area because many of these problems can only be solved within the framework of interdisciplinary and international cooperation.

The development of clean hydrogen and photovoltaic (PV) systems is lagging behind the goals set in the Net Zero Emissions scenario of the International Energy Agency. For this reason efficient hydrogen production systems powered from renewable energy need to be deployed faster. This work presents an optimization procedure for a stand-alone fully PVpowered alkaline electrolysis system. The approach is based on the Particle Swarm Optimization algorithm to obtain the best configuration of the PV plant that powers the electrolyzer and its compressor. The best configuration is determined with one of three indicators: cost efficiency or wasted energy. The PV plant needs to be oversized 2.63 times with respect to the electrolyzer to obtain minimum cost while for high efficiency this number increases by 2%. Additionally the configuration that minimizes cost wasted energy or maximizes efficiency does not correspond to the configuration that maximizes the annual PV yield. Optimizing for cost results also leads to the best operation of the electrolyzer at partial loads than optimizing for efficiency or wasted energy.

An energy systems comparison of grid-electricity derived liquid hydrogen (LH2) and liquid ammonia (LNH3) is conducted to assess their relative potential in a low-carbon future. Under various voyage weather conditions their performance is analysed for use in cargo transport energy vectors for low-carbon electricity transport and fuel supply. The analysis relies on literature projections for technological development and grid decarbonisation towards 2050. Various voyages are investigated from regions such as North America (NA) Europe (E) and Latin America (LA) to regions projected to have a higher electricity and fuel grid carbon intensity (CI) (i.e. Asia Pacific Africa the Middle-East and the CIS). In terms of reducing the CI of electricity and fuel at the destination port use of LH2 is predicted to be favourable relative to LNH3 whereas LNH3 is favourable for low-carbon transport of cargo. As targeted by the International Maritime Organisation journeys of LNH3 cargo ships originating in NA E and LA achieve a reduction in volumetric energy efficiency design index (kg-CO2/m3 -km) of at least 70% relative to 2008 levels. The same targets can be met globally if LH2 is supplied to high CI regions for production of LNH3 for cargo transport. A future shipping system thus benefits from the use of both LH2 and LNH3 for different functions. However there are additional challenges associated with the use of LH2. Relative to LNH3 1.6 to 1.7 times the number of LH2 ships are required to deliver the same energy. Even when reliquefaction is employed their success is reliant on the avoidance of rough sea states (i.e. Beaufort Numbers >= 6) where fuel depletion rates during a voyage are impractical.

As a case study on sustainable energy use in educational institutions this study examines the design and integration of a solar–hydrogen storage system within the energy management framework of Kangwon National University’s Samcheok Campus. This paper provides an extensive analysis of the architecture and integrated design of such a system which is necessary given the increasing focus on renewable energy sources and the requirement for effective energy management. This study starts with a survey of the literature on hydrogen storage techniques solar energy storage technologies and current university energy management systems. In order to pinpoint areas in need of improvement and chances for progress it also looks at earlier research on solar–hydrogen storage systems. This study’s methodology describes the system architecture which includes fuel cell integration electrolysis for hydrogen production solar energy harvesting hydrogen storage and an energy management system customized for the needs of the university. This research explores the energy consumption characteristics of the Samcheok Campus of Kangwon National University and provides recommendations for the scalability and scale of the suggested system by designing three architecture systems of microgrids with EMS Optimization for solar–hydrogen hybrid solar–hydrogen and energy storage. To guarantee effective and safe functioning control strategies and safety considerations are also covered. Prototype creation testing and validation are all part of the implementation process which ends with a thorough case study of the solar–hydrogen storage system’s integration into the university’s energy grid. The effectiveness of the system its effect on campus energy consumption patterns its financial sustainability and comparisons with conventional energy management systems are all assessed in the findings and discussion section. Problems that arise during implementation are addressed along with suggested fixes and directions for further research—such as scalability issues and technology developments—are indicated. This study sheds important light on the viability and efficiency of solar–hydrogen storage systems in academic environments particularly with regard to accomplishing sustainable energy objectives.

The present study describes the development and application of a model of the national electricity system for the Caribbean dual-island nation of Antigua and Barbuda to investigate the cost optimal mix of solar photovoltaics (PVs) wind and in the most novel contribution concentrating solar power (CSP). These technologies together with battery and hydrogen energy storage can enable the aim of achieving 100% renewable electricity and zero carbon emissions. The motivation for this study was that while most nations in the Caribbean rely largely on diesel fuel or heavy fuel oil for grid electricity generation many countries have renewable resources beyond wind and solar energy. Antigua and Barbuda generates 93% of its electricity from diesel-fueled generators and has set the target of becoming a net-zero nation by 2040 as well as having 86% renewable energy generation in the electricity sector by 2030 but the nation has no hydroelectric or geothermal resources. Thus this study aims to demonstrate that CSP is a renewable energy technology that can help assist Antigua and Barbuda in its transition to a renewable energy electric grid while also decreasing electricity generation costs. The modeled optimal mix of renewable energy technologies presented here was found for Antigua and Barbuda by assessing the levelized cost of electricity (LCOE) for systems comprising various combinations of energy technologies and storage. Other factors were also considered such as land use and job creation. It was found that 100% renewable electricity systems are viable and significantly less costly than current power systems and that there is no single defined pathway towards a 100% renewable energy grid but several options are available.

Motivated by the growing importance of fuel cell systems as the basis for distributed energy generation systems this work considers a micro-combined heat and power (mCHP) generation system based on a fuel cell integrated to satisfy the (power and thermal) energy demands of a residential application. The main objective of this work is to compare the performance of several CHP configurations with a conventional alternative in terms of primary energy consumption greenhouse gas (GHG) emissions and economic viability. For that a simulation tool has been developed to easily estimate the electrical and thermal energy generated by a hydrogen fuel cell and all associated results related to the hydrogen production alternatives: excess or shortfall of electrical and thermal energy CO2 emission factor overall performance operating costs payback period etc. A feasibility study of different configuration possibilities of the micro-CHP generation system has been carried out considering different heat-to-power ratios (HPRs) in the possible demands and analyzing primary energy savings CO2 emissions savings and operating costs. An extensive parametric study has been performed to analyze the effect of the fuel cell’s electric power and number of annual operation hours as parameters. Finally a study of the influence of the configuration parameters on the final results has been carried out. Results show that in general configurations using hydrogen produced from natural gas save more primary energy than configurations with hydrogen production from electricity. Furthermore it is concluded that the best operating points are those in which the generation system and the demand have similar HPR. It has also been estimated that a reduction in renewable hydrogen price is necessary to make these systems profitable. Finally it has been determined that the most influential parameters on the results are the fuel cell electrical efficiencies hydrogen production efficiency and hydrogen cost.

Clean energy technological innovations are widely acknowledged as a prerequisite to achieving ambitious longterm energy and climate targets. However the optimal speed of their adoption has been parsimoniously studied in the literature. This study seeks to identify the optimal intensity of moving to a green hydrogen electricity sector in Greece using the OSeMOSYS energy modeling framework. Green hydrogen policies are evaluated first on the basis of their robustness against uncertainty and afterwards against conflicting performance criteria and for different decision-making profiles towards risk by applying the VIKOR and TOPSIS multi-criteria decision aid methods. Although our analysis focuses exclusively on the power sector and compares different rates of hydrogen penetration compared to a business-as-usual case without considering other game-changing innovations (such as other types of storage or carbon capture and storage) we find that a national transition to a green hydrogen economy can support Greece in potentially cutting at least 16 MtCO2 while stimulating investments of EUR 10–13 bn. over 2030–2050.

The realization of a carbon-neutral civilization which has been set as a goal for the coming decades goes directly hand-in-hand with the need for an energy system based on renewable energies (REs). Due to the strong weather-related daily and seasonal fluctuations in supply of REs suitable energy storage devices must be included for such energy systems. For this purpose an energy system model featuring hybrid energy storage consisting of a hydrogen unit (for long-term storage) and a lithium-ion storage device (for short-term storage) was developed. With a proper design such a system can ensure a year-round energy supply by using electricity generated by photovoltaics (PVs). In the energy system that was investigated hydrogen (H2) was produced by using an electrolyser (ELY) with a PV surplus during the summer months and then stored in an H2 tank. During the winter due to the lack of PV power the H2 is converted back into electricity and heat by a fuel cell (FC). While the components of such a system are expensive a resource- and cost-efficient layout is important. For this purpose a Matlab/Simulink model that enabled an energy balance analysis and a component lifetime forecast was developed. With this model the results of extensive parameter studies allowed an optimized system layout to be created for specific applications. The parameter studies covered different focal points. Several ELY and FC layouts different load characteristics different system scales different weather conditions and different load levels—especially in winter with variations in heating demand—were investigated.

Contrails are responsible for a significant proportion of aviation’s climate impact. This paper uses data from the European Centre for Medium-Range Weather Forecasts to identify the altitudes and latitudes where formed contrails will not persist. This reveals that long-lived contrails may be prevented by flying lower in equatorial regions and higher in non-equatorial regions. Subsequently it is found that the lighter fuel and reduced seating capacity of hydrogen-powered aircraft lead to a reduced aircraft weight which increases the optimal operating altitude by about 2 km. In non-equatorial regions this would lift the aircraft’s cruise point into the region where long-lived contrails do not persist unlocking hydrogen-powered low-contrails operation. The baseline aircraft considered is an A320 retrofitted with in-fuselage hydrogen tanks. The impacts of the higher-altitude cruise on fuel burn and the benefits unlocked by optimizing the wing geometry for this altitude are estimated using a drag model based on theory proposed by Cavcar Lock and Mason and verified against existing aircraft. The weight penalty associated with optimizing wing geometry for this altitude is estimated using Torenbeek’s correlation. It is found that thinner wings with higher aspect ratios are particularly suited to this high-altitude operation and are enabled by the relaxation of the requirement to store fuel in the wings. An example aircraft design for the non-equatorial region is provided which cruises at a 14 km altitude at Mach 0.75 with a less than 1% average probability of generating long-lived contrails when operating at latitudes more than 35◦ from the equator. Compared to the A320 this concept design is estimated to have a 20% greater cruise lift–drag ratio due to the 33% thinner wings with a 50% larger aspect ratio enabling just 5% more energy use per passenger-km despite fitting 40% fewer seats.