Applications & Pathways

The current research on green hydrogen can focus from the perspective of production but understanding the demand side is equally important to the initial creation of a hydrogen ecosystem in countries with low industrial activities that can utilise large amounts of hydrogen in the short term. Early movers in these countries must create a demand market in parallel with the green hydrogen plant commissioning. This paper presents research that explores the heavy-duty transport sector as a market-of-interest for early deployment of green hydrogen in Ireland. Conducting a survey-based market research amongst this sector indicate significant interest in hydrogen on the island of Ireland and the barriers the participants presented have been overcome in other jurisdictions. The study develops a model to estimate 1.) the annual hydrogen demand and 2.) the corresponding delivery cost to potential hydrogen consumers either directly or to central hydrogen fuelling hubs.

The energy sector is nowadays facing new challenges mainly in the form of a massive shifting towards renewable energy sources as an alternative to fossil fuels and a diffusion of the distributed generation paradigm which involves the application of small-scale energy generation systems. In this scenario systems adopting one or more renewable energy sources and capable of producing several forms of energy along with some useful substances such as fresh water and hydrogen are a particularly interesting solution. A hybrid polygeneration system based on renewable energy sources can overcome operation problems regarding energy systems where only one energy source is used (solar wind biomass) and allows one to use an all-in-one integrated systems in order to match the different loads of a utility. From the point of view of scientific literature medium and large-scale systems are the most investigated; nevertheless more and more attention has also started to be given to small-scale layouts and applications. The growing diffusion of distributed generation applications along with the interest in multipurpose energy systems based on renewables and capable of matching different energy demands create the necessity of developing an overview on the topic of small-scale hybrid and polygeneration systems. Therefore this paper provides a comprehensive review of the technology operation performance and economical aspects of hybrid and polygeneration renewable energy systems in small-scale applications. In particular the review presents the technologies used for energy generation from renewables and the ones that may be adopted for energy storage. A significant focus is also given to the adoption of renewable energy sources in hybrid and polygeneration systems designs/modeling approaches and tools and main methodologies of assessment. The review shows that investigations on the proposed topic have significant potential for expansion from the point of view of system configuration hybridization and applications.

Ammonia (NH3) is among the largest-volume chemicals produced and distributed in the world and is mainly known for its use as a fertilizer in the agricultural sector. In recent years it has sparked interest in the possibility of working as a high-quality energy carrier and as a carbon-free fuel in internal combustion engines (ICEs). This review aimed to provide an overview of the research on the use of green ammonia as an alternative fuel for ICEs with a look to the future on possible applications and practical solutions to related problems. First of all the ammonia production process is discussed. Present ammonia production is not a “green” process; the synthesis occurs starting from gaseous hydrogen currently produced from hydrocarbons. Some ways to produce green ammonia are reviewed and discussed. Then the chemical and physical properties of ammonia as a fuel are described and explained in order to identify the main pros and cons of its use in combustion systems. Then the most viable solutions for fueling internal combustion engines with ammonia are discussed. When using pure ammonia high boost pressure and compression ratio are required to compensate for the low ammonia flame speed. In spark-ignition engines adding hydrogen to ammonia helps in speeding up the flame front propagation and stabilizing the combustion. In compression-ignition engines ammonia can be successfully used in dual-fuel mode with diesel. On the contrary an increase in NOx and the unburned NH3 at the exhaust require the installation of apposite aftertreatment systems. Therefore the use of ammonia seems to be more practicable for marine or stationary engine application where space constraints are not a problem. In conclusion this review points out that ammonia has excellent potential to play a significant role as a sustainable fuel for the future in both retrofitted and new engines. However significant further research and development activities are required before being able to consider large-scale industrial production of green ammonia. Moreover uncertainties remain about ammonia safe and effective use and some technical issues need to be addressed to overcome poor combustion properties for utilization as a direct substitute for standard fuels.

Fuel cells as key carriers for hydrogen energy development and utilization provide a vital opportunity to achieve zero-emission energy use and have thus attracted considerable attention from fundamental research to industrial application levels. Considering the current status of fuel cell technology and the industry this paper presents a systematic elaboration of progress and development trends in fuel cell core components and key materials such as stacks bipolar plates membrane electrodes proton exchange membranes catalysts gas diffusion layers air compressors and hydrogen circulation systems. In addition some proposals for the development of fuel cell vehicles in China are presented based on the analysis of current supporting policies standards and regulations along with manufacturing costs in China. The fuel cell industry of China is still in the budding stage of development and thus suffers some challenges such as lagging fundamental systems imperfect standards and regulations high product costs and uncertain technical safety and stability levels. Therefore to accelerate the development of the hydrogen energy and fuel cell vehicle industry it is an urgent need to establish a complete supporting policy system accelerate technical breakthroughs transformations and applications of key materials and core components and reduce the cost of hydrogen use.

In this fifth episode  Steffan Eldred and Neelam Mughal from Innovate UK KTN discuss how the glass industry is driving new hydrogen developments and research and explore the hydrogen transition opportunities and challenges in this sector alongside their special guest Rob Ireson Innovation and Partnerships Manager at Glass Futures Ltd.

The podcast can be found on their website

The world-wide sustainability implications of transport technologies remain unclear because their assessment often relies on metrics that are hard to interpret from a global perspective. To contribute to filling this gap here we apply the concept of planetary boundaries (PBs) i.e. a set of biophysical limits critical for operating the planet safely to address the optimal design of sustainable fuel supply chains (SCs) focusing on hydrogen for vehicle use. By incorporating PBs into a mixed-integer linear programming model (MILP) we identify SC configurations that satisfy a given transport demand while minimising the PBs transgression level i.e. while reducing the risk of surpassing the ecological capacity of the Earth. On applying this methodology to the UK we find that the current fossil-based sector is unsustainable as it transgresses the energy imbalance CO2 concentration and ocean acidification PBs heavily i.e. five to 55-fold depending on the downscale principle. The move to hydrogen would help to reduce current transgression levels substantially i.e. reductions of 9–86% depending on the case. However it would be insufficient to operate entirely within all the PBs concurrently. The minimum impact SCs would produce hydrogen via water electrolysis powered by wind and nuclear energy and store it in compressed form followed by distribution via rail which would require as much as 37 TWh of electricity per year. Our work unfolds new avenues for the incorporation of PBs in the assessment and optimisation of energy systems to arrive at sustainable solutions that are entirely consistent with the carrying capacity of the planet.

Hydrogen energy and fuel cell technology are critical clean energy roads to pursue carbon neutrality. The proton exchange membrane fuel cell (PEMFC) has a wide range of commercial application prospects due to its simple structure easy portability and quick start-up. However the cost and durability of the PEMFC system are the main barriers to commercial applications of fuel cell vehicles. In this paper the core hydrogen recirculation components of fuel cell vehicles including mechanical hydrogen pumps ejectors and gas–water separators are reviewed in order to understand the problems and challenges in the simulation design and application of these components. The types and working characteristics of mechanical pumps used in PEMFC systems are summarized. Furthermore corresponding design suggestions are given based on the analysis of the design challenges of the mechanical hydrogen pump. The research on structural design and optimization of ejectors for adapting wide power ranges of PEMFC systems is analyzed. The design principle and difficulty of the gas–water separator are summarized and its application in the system is discussed. In final the integration and control of hydrogen recirculation components controlled cooperatively to ensure the stable pressure and hydrogen supply of the fuel cell under dynamic loads are reviewed.

The hydrogen storage pressure in fuel cell vehicles has been increased from 35 MPa to 70 MPa in order to accommodate longer driving range. On the downside such pressure increase results in significant temperature rise inside the hydrogen tank during fast filling at a fueling station which may pose safety issues. Installation of a chiller often mitigates this concern because it cools the hydrogen gas before its deposition into the tank. To address both the energy efficiency improvement and safety concerns this paper proposed an on-board cold thermal energy storage (CTES) system cooled by expanded hydrogen. During the driving cycle the proposed system uses an expander instead of a pressure regulator to generate additional power and cold hydrogen gas. Moreover CTES is equipped with phase change materials (PCM) to recover the cold energy of the expanded hydrogen gas which is later used in the next filling to cool the high-pressure hydrogen gas from the fueling station.

This paper explores the effect of having a nuclear baseload in a 100% carbon-free electricity system The study analyses numerous 8 scenarios based on different penetrations of conventional nuclear wind and solar PV power different levels of overgeneration 9 and different combinations between medium and long duration energy stores (hydrogen and compressed air respectively) to 10 determine the configuration that achieves the lowest total cost of electricity (TCoE). 11 At their current cost new baseload nuclear power plants are too expensive. Results indicate the TCoE is minimised when demand 12 is supplied entirely by renewables with no contribution from conventional nuclear. 13 However small modular reactors may achieve costs of ~£60/MWh (1.5x current wind cost) in the future. With such costs 14 supplying ~80% of the country’s electricity demand with nuclear power could minimise the TCoE. In this scenario wind provides 15 the remaining 20% plus a small percentage of overgeneration (~2.5%). Hydrogen in underground caverns provides ~30.5 TWh (81 16 days) of long-duration energy storage while CAES systems provide 2.8 TWh (~8 days) of medium-duration storage. This 17 configuration achieves costs of ~65.8 £/MWh. Batteries (required for short duration imbalances) are not included in the figure. 18 The TCoE achieved will be higher once short duration storage is accounted for.

The energy transition with transformation into predominantly renewable sources requires technology development to secure power production at all times despite the intermittent nature of the renewables. Micro gas turbines (MGTs) are small heat and power generation units with fast startup and load-following capability and are thereby suitable backup for the future’s decentralized power generation systems. Due to MGTs’ fuel flexibility a range of fuels from high-heat to lowheat content could be utilized with different greenhouse gas generation. Developing micro gas turbines that can operate with carbon-free fuels will guarantee carbon-free power production with zero CO2 emission and will contribute to the alleviation of the global warming problem. In this paper the redevelopment of a standard 100-kW micro gas turbine to run with methane/hydrogen blended fuel is presented. Enabling micro gas turbines to run with hydrogen blended fuels has been pursued by researchers for decades. The first micro gas turbine running with pure hydrogen was developed in Stavanger Norway and launched in May 2022. This was achieved through a collaboration between the University of Stavanger (UiS) and the German Aerospace Centre (DLR). This paper provides an overview of the project and reports the experimental results from the engine operating with methane/hydrogen blended fuel with various hydrogen content up to 100%. During the development process the MGT’s original combustor was replaced with an innovative design to deal with the challenges of burning hydrogen. The fuel train was replaced with a mixing unit new fuel valves and an additional controller that enables the required energy input to maintain the maximum power output independent of the fuel blend specification. This paper presents the test rig setup and the preliminary results of the test campaign which verifies the capability of the MGT unit to support intermittent renewable generation with minimum greenhouse gas production. Results from the MGT operating with blended methane/hydrogen fuel are provided in the paper. The hydrogen content varied from 50% to 100% (volume-based) and power outputs between 35 kW to 100kW were tested. The modifications of the engine mainly the new combustor fuel train valve settings and controller resulted in a stable operation of the MGT with NOx emissions below the allowed limits. Running the engine with pure hydrogen at full load has resulted in less than 25 ppm of NOx emissions with zero carbon-based greenhouse gas production.

As the demand for eco-friendly energy increases hydrogen energy and liquid hydrogen storage technologies are being developed as an alternative. Hydrogen has a lower liquefaction point and higher thermal conductivity than nitrogen or neon used in general cryogenic systems. Therefore the application of hydrogen to cryogenic systems can increase efficiency and stability. This paper describes the design and analysis of a cryogenic cooling system for an electric propulsion system using liquid hydrogen as a refrigerant and energy source. The proposed aviation propulsion system (APS) consists of a hydrogen fuel cell a battery a power distribution system and a motor. For a lab-scale 5 kW superconducting motor using a 2G high-temperature superconducting (HTS) wire the HTS motor and cooling system were analyzed for electromagnetic and thermal characteristics using a finite element method-based analysis program. The liquid hydrogen-based cooling system consists of a pre-cooling system a hydrogen liquefaction system and an HTS coil cooling system. Based on the thermal load analysis results of the HTS coil the target temperature for hydrogen gas pre-cooling the number of buffer layers and the cryo-cooler capacity were selected to minimize the thermal load of the hydrogen liquefaction system. As a result the hydrogen was stably liquefied and the temperature of the HTS coil corresponding to the thermal load of the designed lab-scale HTS motor was maintained at 30 K.

Modelling simulation optimization and control strategies are used in this study to design a stand-alone solar PV/Fuel Cell/Battery/Generator hybrid power system to serve the electrical load of a commercial building. The main objective is to design an off grid energy system to meet the desired electric load of the commercial building with high renewable fraction low emissions and low cost of energy. The goal is to manage the energy consumption of the building reduce the associate cost and to switch from grid-tied fossil fuel power system to an off grid renewable and cleaner power system. Energy audit was performed in this study to determine the energy consumption of the building. Hourly simulations modelling and optimization were performed to determine the performance and cost of the hybrid power configurations using different control strategies. The results show that the hybrid off grid solar PV/Fuel Cell/Generator/Battery/Inverter power system offers the best performance for the tested system architectures. From the total energy generated from the off grid hybrid power system 73% is produced from the solar PV 24% from the fuel cell and 3% from the backup Diesel generator. The produced power is used to meet all the AC load of the building without power shortage (<0.1%). The hybrid power system produces 18.2% excess power that can be used to serve the thermal load of the building. The proposed hybrid power system is sustainable economically viable and environmentally friendly: High renewable fraction (66.1%) low levelized cost of energy (92 $/MWh) and low carbon dioxide emissions (24 kg CO₂/MWh) are achieved.

With increasing concerns on transportation decarbonization fuel cell hybrid trains (FCHTs) attract many attentions due to their zero carbon emissions during operation. Since fuel cells alone cannot recover the regenerative braking energy (RBE) energy storage devices (ESDs) are commonly deployed for the recovery of RBE and provide extra traction power to improve the energy efficiency. This paper aims to minimize the net hydrogen consumption (NHC) by co-optimizing both train speed trajectory and onboard energy management using a time-based mixed integer linear programming (MILP) model. In the case with the constraints of speed limits and gradients the NHC of co-optimization reduces by 6.4% compared to the result obtained by the sequential optimization which optimizes train control strategies first and then the energy management. Additionally the relationship between NHC and employed ESD capacity is studied and it is found that with the increase of ESD capacity the NHC can be reduced by up to 30% in a typical route in urban railway transit. The study shows that ESDs play an important role for FCHTs in reducing NHC and the proposed time-based co-optimization model can maximize the energy-saving benefits for such emerging traction systems with hybrid energy sources including both fuel cells and ESD.

The present day energy supply scenario is unsustainable and the transition towards a more environmentally friendly energy supply system of the future is inevitable. Hydrogen is a potential fuel that is capable of assisting with this transition. Certain technological advancements and design challenges associated with hydrogen generation and fuel cell technologies are discussed in this review. The commercialization of hydrogen-based technologies is closely associated with the development of the fuel cell industry. The evolution of fuel cell electric vehicles and fuel cell-based stationary power generation products in the market are discussed. Furthermore the opportunities and threats associated with the market diffusion of these products certain policy implications and roadmaps of major economies associated with this hydrogen transition are discussed in this review.

A proton exchange membrane fuel cell (PEMFC) system requires an adequate hydrogen supply and circulation to achieve its expected performance and operating life. An ejector-based hydrogen circulation system can reduce the operating and maintenance costs noise and parasitic power consumption by eliminating the recirculation pump. However the ejector’s hydrogen entrainment capability restricted by its geometric parameters and flow control variability can only operate properly within a relatively narrow range of fuel cell output power. This research introduced the optimal design and operation control methods of a dual-ejector hydrogen supply/circulation system to support the full range of PEMFC system operations. The technique was demonstrated on a 70 kW PEMFC stack with an effective hydrogen entrainment ratio covering 8% to 100% of its output power. The optimal geometry design ensured each ejector covered a specific output power range with maximized entrainment capability. Furthermore the optimal control of hydrogen flow and the two ejectors’ opening and closing times minimized the anode gas pressure fluctuation and reduced the potential harm to the PEMFC’s operation life. The optimizations were based on dedicated computational fluid dynamics (CFD) and system dynamics models and simulations. Bench tests of the resulting ejector-based hydrogen supply/circulation system verified the simulation and optimization results.

Hybrid energy storage systems (HESS) are considered for use in renewable residential DC microgrids. This architecture is shown as a technically feasible solution to deal with the stochasticity of renewable energy sources however the complexity of its design and management increases inexorably. To address this problem this paper proposes a fuzzy logic-based energy management system (EMS) for use in grid-connected residential DC microgrids with HESS. It is a hydrogen-based HESS composed of batteries and multi-stack fuel cell system. The proposed EMS is based on a multivariable and multistage fuzzy logic controller specially designed to cope with a multi-objective problem whose solution increases the microgrid performance in terms of efficiency operating costs and lifespan of the HESS. The proposed EMS considers the power balance in the microgrid and its prediction the performance and degradation of its subsystems as well as the main electricity grid costs. This article assesses the performance of the developed EMS with respect to three reference EMSs present in the literature: the widely used dual-band hysteresis and two based on multi-objective model predictive control. Simulation results show an increase in the performance of the microgrid from a technical and economic point of view.

The reduction of greenhouse gas emissions is one of the greatest global challenges through 2050. Besides greenhouse gas emissions air pollution such as nitrogen oxide and particulate matter emissions has gained increasing attention in agglomerated areas with transport vehicles being one of the main sources thereof. Alternative fuels that fulfill the greenhouse gas reduction goals also offer the possibility of solving the challenge of rising urban pollution. This work focuses on the electric drive option for heavy and light duty vehicle freight transport. In this study fuel cell-electric vehicles battery-electric vehicles and overhead catenary line trucks were investigated taking a closer look at their potential to reduce greenhouse gas emissions and air pollution and also considering the investment and operating costs of the required infrastructure. This work was conducted using a bottom-up transport model for the federal state of North Rhine-Westphalia in Germany. Two scenarios for reducing these emissions were analyzed at a spatial level. In the first of these selected federal highways with the highest traffic volume were equipped with overhead catenary lines for the operation of diesel-hybrid overhead trucks on them. For the second spatial scenario the representative urban area of the city of Cologne was investigated in terms of air pollution shifting articulated trucks to diesel-hybrid overhead trucks and rigid trucks trailer trucks and light duty vehicles to battery-electric or fuel cell-electric drives. For the economic analysis the building up of a hydrogen infrastructure in the cases of articulated trucks and all heavy duty vehicles were also taken into account. The results showed that diesel-hybrid overhead trucks are only a cost-efficient solution for highways with high traffic volume whereas battery overhead trucks have a high uncertainty in terms of costs and technical feasibility. In general the broad range of costs for battery overhead trucks makes them competitive with fuel cell-electric trucks. Articulated trucks have the highest potential to be operated as overhead trucks. However the results indicated that air pollution is only partially reduced by switching conventional articulated trucks to electric drive models. The overall results show that a comprehensive approach such as fuel cell-electric drives for all trucks would most likely be more beneficial.

The production of fat steel products is commonly linked to highly integrated sites which include hot metal generation via the blast furnace basic oxygen furnace (BOF) continuous casting and subsequent hot-rolling. In order to reach carbon neutrality a shift away from traditional carbon-based metallurgy is required within the next decades. Direct reduction (DR) plants are capable to support this transition and allow even a stepwise reduction in CO2 emissions. Nevertheless the implementation of these DR plants into integrated metallurgical plants includes various challenges. Besides metallurgy product quality and logistics special attention is given on future energy demand. On the basis of carbon footprint methodology (ISO 14067:2019) diferent scenarios of a stepwise transition are evaluated and values of possible CO2equivalent (CO2eq) reduction are coupled with the demand of hydrogen electricity natural gas and coal. While the traditional blast furnace—BOF route delivers a surplus of electricity in the range of 0.7 MJ/kg hot-rolled coil; this surplus turns into a defcit of about 17 MJ/ kg hot-rolled coil for a hydrogen-based direct reduction with an integrated electric melting unit. On the other hand while the product carbon footprint of the blast furnace-related production route is 2.1 kg CO2eq/kg hot-rolled coil; this footprint can be reduced to 0.76 kg CO2eq/kg hot-rolled coil for the hydrogen-related route provided that the electricity input is from renewable energies. Thereby the direct impact of the processes of the integrated site can even be reduced to 0.15 kg CO2eq/ kg hot-rolled coil. Yet if the electricity input has a carbon footprint of the current German or European electricity grid mix the respective carbon footprint of hot-rolled coil even increases up to 3.0 kg CO2eq/kg hot-rolled coil. This underlines the importance of the availability of renewable energies.

The integration of electrolyzers and fuel cells can cause voltage fluctuations within microgrids if not properly scheduled. Therefore controlling voltage and reactive power becomes crucial to mitigate the impact of fluctuating voltage levels ensuring system stability and preventing damage to equipment. This paper therefore seeks to enhance voltage and reactive power control within reconfigurable microgrids in the presence of innovative power-to-hydrogen technologies via electrolyzers and hydrogen-to-power through fuel cells. Specifically it focuses on the simultaneous coordination of an electrolyzer hydrogen storage and a fuel cell alongside on-load tap changers smart photovoltaic inverters renewable energy sources diesel generators and electric vehicle aggregation within the microgrid system. Additionally dynamic network reconfiguration is employed to enhance microgrid flexibility and improve the overall system adaptability. Given the inherent unpredictability linked to resources the unscented transformation method is employed to account for these uncertainties in the proposed voltage and reactive power management. Finally the model is formulated as a convex optimization problem and is solved through GUROBI version 11 which leads to having a time-efficient model with high accuracy. To assess the effectiveness of the model it is eventually examined on a modified 33-bus microgrid in several cases. Through the results of the under-study microgrid the developed model is a great remedy for the simultaneous operation of diverse resources in reconfigurable microgrids with a flatter voltage profile across the microgrid.

Hydrogen offers an effective pathway for the large‑scale storage of renewable energy. For a tourist city located in a plateau region rich in renewable energy hydrogen shows great potential for reducing carbon emissions and utilizing uncertain renewable energy. Herein the wind–solar–hydrogen stand‑alone and grid‑connected systems in the plateau tourist city of Lijiang City in Yunnan Province are modeled and techno‑economically evaluated by using the HOMER Pro software (version 3.14.2) with the multi‑criteria decision anal‑ ysis models. The system is composed of 5588 kW solar photovoltaic panels an 800 kW wind turbine a 1600 kW electrolyzer a 421 kWh battery and a 50 kW fuel cell. In addi‑ tion to meeting the power requirements for system operation the system has the capacity to provide daily electricity for 200 households in a neighborhood and supply 240 kg of hydrogen per day to local hydrogen‑fueled buses. The stand‑alone system can produce 10.15 × 106 kWh of electricity and 93.44 t of hydrogen per year with an NPC of USD 8.15 million an LCOE of USD 0.43/kWh and an LCOH of USD 5.26/kg. The grid‑connected system can generate 10.10 × 106 kWh of electricity and 103.01 ton of hydrogen annually. Its NPC is USD 7.34 million its LCOE is USD 0.11/kWh and its LCOH is USD 3.42/kg. This study provides a new solution for optimizing the configuration of hybrid renewable en‑ ergy systems which will develop the hydrogen economy and create low‑carbon‑emission energy systems.

Population growth and economic development have significantly increased global energy demand. Hence it has raised concerns about the increase in the consumption of fossil fuels and climate change. The present work introduced a new approach to using carbon-free energy sources such as nuclear and renewable to meet energy demand. The idea of using the Nuclear-Renewable Hybrid Energy System (N-R HES) is suggested as a leading solution that couples a nuclear power plant with renewable energy and hydrogen-based storage systems. For this purpose using a meta-heuristic method based on Newton’s laws the configuration of the N-R HES is optimized from an economic and reliability point of view. The optimal system is selected from among six cases with different subsystems such as wind turbine photovoltaic panel nuclear reactor electrolysis fuel cell and hydrogen storage tank. Furthermore the performance of hydrogen-based energy storage systems such as hightemperature electrolysis (HTE) and low-temperature electrolysis (LTE) is evaluated from technical and economic aspects. The results of this work showed that using nuclear energy to supply the base load increases the reliability of the system and reduces the loss of power supply probability to zero. More than 70 % of the power is produced by nuclear reactors which includes more than 80 % of the system costs. The key findings showed that despite HTE’s higher efficiency using LTE as a storage system in N-R HES is more cost-effective. Finally due to recent developments and the safer design of nuclear reactors they can play an important role in combination with renewable energies to support carbon-free energy sectors especially in remote areas for decades to come.

Sustainability goals include the utilization of renewable energy resources to supply the energy needs in addition to wastewater treatment to satisfy the water demand. Moreover hydrogen has become a promising energy carrier and green fuel to decarbonize the industrial and transportation sectors. In this context this research investigates a wind-photovoltaic power plant to produce green hydrogen for hydrogen refueling station and to operate an electrocoagulation water treatment unit in Ostrava Czech Republic’s northeast region. The study conducts a techno-economic analysis through HOMER Pro® software for optimal sizing of the power station components and to investigate the economic indices of the plant. The power station employs photovoltaic panels and wind turbines to supply the required electricity for electrolyzers and electrocoagulation reactors. As an offgrid system lead acid batteries are utilized to store the surplus electricity. Wind speed and solar irradiation are the key role site dependent parameters that determine the cost of hydrogen electricity and wastewater treatment. The simulated model considers the capital operating and replacement costs for system components. In the proposed system 240 kg of hydrogen as well as 720 kWh electrical energy are daily required for the hydrogen refueling station and the electrocoagulation unit respectively. Accordingly the power station annually generates 6997990 kWh of electrical energy in addition to 85595 kg of green hydrogen. Based on the economic analysis the project’s NPC is determined to be €5.49 M and the levelized cost of Hydrogen (LCH) is 2.89 €/kg excluding compressor unit costs. This value proves the effectiveness of this power system which encourages the utilization of green hydrogen for fuel-cell electric vehicles (FCVs). Furthermore emerging electrocoagulation studies produce hydrogen through wastewater treatment increasing hydrogen production and lowering LCH. Therefore this study is able to provide practicable methodology support for optimal sizing of the power station components which is beneficial for industrialization and economic development as well as transition toward sustainability and autonomous energy systems.

Growing interest in sustainable energy has gathered significant attention for alternative technologies with hydrogen-based solutions emerging as a crucial component in the transition to cleaner and more resilient energy systems. Following that hydrogenbased microgrids integrated with renewable energy sources including wind and solar have gained substantial attention as an upcoming pathway toward long-term energy sustainability. Hydrogen produced through processes such as electrolysis and steam methane reforming can be stored in various forms including compressed gas liquid or solid-state hydrides and later utilized for electricity generation through fuel cells and gas turbines. This dynamic energy system offers highly flexible scalable and resilient solutions for various applications. Specifically hydrogen-based microgrids are particularly suitable for offshore and islanded applications with geographical factors adverse environmental conditions and limited access to conventional energy solutions. This is critical for energy independence long-term storage capacity and grid stability. This review explores topological and functional-based classifications of microgrids advancements in hydrogen generation storage and utilization technologies and their integration with microgrid systems. It also critically evaluates the key challenges of each technology including cost efficiency and scalability which impact the feasibility of hydrogen microgrids.

Solid oxide cells (SOC) play a major role in strategic visions to achieve decarbonization and climate-neutrality. With its multifuel capability this technology has received rapidly growing amount of attention from researchers worldwide. Due to the great flexibility of SOCs with respect to the fuels that can be used not only hydrogen but also biogas natural gas diesel reformates and many other conventional and alternative fuels can be used. This makes it possible to couple SOCs with diverse sustainable fuel sources to generate electricity or to generate valuable fuels such as syngas when utilizing renewable electricity. In this paper the reader is provided with a review of the existing knowledge about solid oxide fuel cell (SOFC) and solid oxide electrolysis (SOE) systems and how to safely operate them over the long-term placing a special focus on real-world operating environments. Both the utilization and generation of real commercially available fuels are taken into consideration. Different failure modes can appear during the system operation under real-world conditions and reduce the SOC lifetime an aspect that is extensively discussed in this review. Firstly a detailed discussion of the difference between carbon-free and carbon-containing fuels is presented considering different impurities and their impacts on the SOC performance stability and lifetime. Secondly unfavorable operating conditions are presented and possibilities for the early identification of different failure modes are explored. An overview of available conventional and non-conventional diagnostic tools and their applications is provided here. Overall this review paper presents a guideline for all relevant degradation issues related to SOCs operated in a real-world environment describing (i) how these issues appear and how to understand them (ii) how to predict them (iii) how to identify them and (iv) how to prevent them as well as if required how to reverse them. To achieve this goal individual chapters specifically address failure modes degradation prediction degradation prevention and performance regeneration. The reader is provided with necessary knowledge about the long-term and short-term operating stability and the degradation provoked in a compact summary. The available knowledge about specific process frequencies is summarized in one diagram which is a novel contribution of this review. This enables researchers to rapidly identify all occurring process mechanisms with SOFCs and SOECs. Moreover suggestions for how to accelerate degradation and how to regenerate performance are summarized in several tables.

Integrating electric technologies such as battery energy storage systems and electric propulsion has become an appealing option for reducing fuel consumption and emissions in the transportation sector making these technologies increasingly popular for research and industrial application in the maritime sector. In addition hydrogen is a promising technology for reducing emissions although hydrogen production technologies significantly influence the overall impact of hydrogen-powered systems. This paper proposes an optimizationbased strategy to minimize the environmental impact of a hybrid propulsion system over a given load profile while furthermore considering the environmental impact resulting from the hydrogen production chain. The propulsion system includes diesel generators hydrogen-powered fuel cells batteries and electric motors; mathematical models and assumptions are discussed in detail. The paper applies the proposed strategy and compares different hybrid solutions considering equivalent CO2 emissions discussing a test case applied to a short-range ferry operating in a marine protected area an area particularly sensitive to the problem of atmospheric emissions. The results demonstrate that the proposed strategy can reduce greenhouse gas emissions by up to 73% compared to a conventional mechanical propulsion system.