Applications & Pathways

The depletion of fossil fuel sources has encouraged the authorities to use renewable resources such as wind energy to generate electricity. A backup/storage system can improve the performance of wind turbines due to fluctuations in power demand. The novelty of this study is to utilize a hybrid system for a wind farm using the excess electricity generated by the wind turbines to produce hydrogen in an alkaline electrolyzer (AEL). The hydrogen storage tank stores the produced hydrogen and provides hydrogen to the proton-exchange membrane fuel cell (PEMFC) to generate electricity once the power demand is higher than the electricity generated by the wind turbines. The goal of this study is to use the wind profile of a region in Iran namely the Cohen region to analyze the performance of the suggested integrated system on a micro scale. The output results of this study can be used as a case study for construction in the future based on the exact specification of NTK300 wind turbines. The results indicate that with the minimum power supply of 30 kW from the wind turbines on a lab scale the generated power by the PEMFC will be 1008 W while the maximum generated hydrogen will be 304 mL/h.

The shift from fossil fuels to renewable energy systems represents a pivotal step toward the realization of a sustainable society. This study aims to analyze representative scientific literature on eco-sustainable energy production in the healthcare sector particularly in hospitals. Given hospitals’ substantial electricity consumption the adoption of renewable energy offers a reliable low-CO2 emission solution. The COVID-19 pandemic has underscored the urgency for energyefficient and environmentally-responsible approaches. This brief review analyzes the development of experimental simulation and optimization projects for sustainable energy production in healthcare facilities. The analysis reveals trends and challenges in renewable energy systems offering valuable insights into the potential of eco-sustainable solutions in the healthcare sector. The findings indicate that hydrogen storage systems are consistently coupled with photovoltaic panels or solar collectors but only 14% of the analyzed studies explore this potential within hospital settings. Hybrid renewable energy systems (HRES) could be used to meet the energy demands of healthcare centers and hospitals. However the integration of HRES in hospitals and medical buildings is understudied.

The economic competitiveness of hydrogen-powered aviation highly depends on the supply costs of green liquid hydrogen to enable true-zero CO2 flying. This study uses non-linear energy system optimization to analyze three main liquid hydrogen (LH2) supply pathways for five locations. Final liquid hydrogen costs at the dispenser supply costs could reach 2.04 USD/kgLH2 in a 2050 base case scenario for locations with strong renewable energy source conditions. This could lead to cost-competitive flying with hydrogen. Reflecting techno-economic uncertainties in two additional scenarios the liquid hydrogen cost span at all five airport locations ranges between 1.37–3.48 USD/kgLH2 if hydrogen import options from larger hydrogen markets are also available. Import setups are of special importance for airports with a weaker renewable energy source situation e.g. selected Central European airports. There on-site supply might not only be too expensive but space requirements for renewable energy sources could be too large for feasible implementation in densely populated regions. Furthermore main costs for liquid hydrogen are caused by renewable energy sources electrolysis systems and liquefaction plants. Seven detailed design rules are derived for optimized energy systems for these and the storage components. This and the cost results should help infrastructure planners and general industry and policy players prioritize research and development needs

Decarbonising and decontaminating remote regions in the world presents several challenges. Many of these regions feature isolation dispersed demand in large areas and a lack of economic resources that impede the development of robust and sustainable networks. Furthermore isolated systems in the developing world are mostly based on diesel generation for electricity and firewood and liquefied petroleum gas for heating as these options do not require a significant infrastructure cost. In this context we present a stochastic multi-energy multi-microgrid system planning model that integrates electricity heat and hydrogen networks in isolated systems. The model is stochastic to capture uncertainty in renewable generation outputs particularly hydro and wind and thus design a multi-energy system proved secured against such uncertainty. The model also features two distinct constraints to limit the emissions of CO2 (for decarbonisation) and particulate matter (for decontamination) and incorporates firewood as a heating source. Moreover given that the focus is on low-voltage networks we introduce a fully linear AC power flow equations set allowing the planning model to remain tractable. The model is applied to a real-world case study to design a multi-energy multi-microgrid system in an isolated region in Chilean Patagonia. In a case with a zero limit over direct CO2 emissions the total system’s cost increases by 34% with respect to an unconstrained case. In a case with a zero limit over particulate matter emissions the total system’s cost increases by 189%. Finally although an absolute zero limit over both particulate matter and direct CO2 emissions leads to a total system’s cost increase of 650% important benefits in terms of decarbonisation and decontamination can be achieved at marginal cost increments.

In light of offshore wind expansions in the North and Baltic Seas in Europe further ideas on using offshore space for renewable-based energy generation have evolved. One of the concepts is that of energy islands which entails the placement of energy conversion and storage equipment near offshore wind farms. Offshore placement of electrolysers will cause interdependence between the availability of electricity for hydrogen production and for power transmission to shore. This paper investigates the trade-offs between integrating energy islands via electricity versus hydrogen infrastructure. We set up a combined capacity expansion and electricity dispatch model to assess the role of electrolysers and electricity cables given the availability of renewable energy from the islands. We find that the electricity system benefits more from connecting close-to-shore wind farms via power cables. In turn electrolysis is more valuable for far-away energy islands as it avoids expensive long-distance cable infrastructure. We also find that capacity investment in electrolysers is sensitive to hydrogen prices but less to carbon prices. The onshore network and congestion caused by increased activity close to shore influence the sizing and siting of electrolysers.

Hydrogen is considered as a promising fuel in the 21st century due to zero tailpipe CO2 emissions from hydrogen-powered vehicles. The use of hydrogen as fuel in vehicles can play an important role in decarbonising the transport sector and achieving net-zero emissions targets. However there exist several issues related to hydrogen production efficient hydrogen storage system and transport and refuelling infrastructure where the current research is focussing on. This study critically reviews and analyses the recent technological advancements of hydrogen production storage and distribution technologies along with their cost and associated greenhouse gas emissions. This paper also comprehensively discusses the hydrogen refuelling methods identifies issues associated with fast refuelling and explores the control strategies. Additionally it explains various standard protocols in relation to safe and efficient refuelling analyses economic aspects and presents the recent technological advancements related to refuelling infrastructure. This study suggests that the production cost of hydrogen significantly varies from one technology to others. The current hydrogen production cost from fossil sources using the most established technologies were estimated at about $0.8–$3.5/kg H2 depending on the country of production. The underground storage technology exhibited the lowest storage cost followed by compressed hydrogen and liquid hydrogen storage. The levelised cost of the refuelling station was reported to be about $1.5–$8/kg H2 depending on the station's capacity and country. Using portable refuelling stations were identified as a promising option in many countries for small fleet size low-to-medium duty vehicles. Following the current research progresses this paper in the end identifies knowledge gaps and thereby presents future research directions.

This paper provides a comprehensive review of the research progress current state-ofthe-art and future research directions of energy storage systems. With the widespread adoption of renewable energy sources such as wind and solar power the discourse around energy storage is primarily focused on three main aspects: battery storage technology electricity-to-gas technology for increasing renewable energy consumption and optimal configuration technology. The paper employs a visualization tool (CiteSpace) to analyze the existing works of literature and conducts an in-depth examination of the energy storage research hotspots in areas such as electrochemical energy storage hydrogen storage and optimal system configuration. It presents a detailed overview of common energy storage models and configuration methods. Based on the reviewed articles the future development of energy storage will be more oriented toward the study of power characteristics and frequency characteristics with more focus on the stability effects brought by transient shocks. This review article compiles and assesses various energy storage technologies for reference and future research.

Ever more stringent emission regulations for vehicles encourage increasing numbers of battery electric vehicles on the roads. A drawback of storing electric energy in a battery is the comparable low energy density low driving range and the higher propensity to deplete the energy storage before reaching the destination especially at low ambient temperatures. When the battery is depleted stranded vehicles can either be towed or recharged with a mobile recharging station. Several technologies of mobile recharging stations already exist however most of them use fossil fuels to recharge battery electric vehicles. The proposed novel zero emission solution for mobile charging is a combined high voltage battery and hydrogen fuel cell charging station. Due to the thermal characteristics of the fuel cell and high voltage battery (which allow only comparable low coolant temperatures) the thermal design for this specific application (available heat exchanger area zero vehicle speed air flow direction) becomes challenging and is addressed in this work. Experimental methods were used to obtain reliable thermal and electric power measurement data of a 30 kW fuel cell system which is used in the Mobile Hydrogen Powersupply. Subsequently simulation methods were applied for the thermal design and optimisation of the coolant circuits and heat exchangers. It is shown that an battery electric vehicle charging power of 22 kW requires a heat exchanger area of 1 m2 of which 60 % is used by the fuel cell heat exchanger and the remainder by the battery heat exchanger to achieve steady state operation at the highest possible ambient temperature of 436 °C. Furthermore the simulation showed that when the charging power of 22 kW is solely provided by the high voltage battery the highest possible ambient temperature is 42 °C. When the charging power is decreased operation up to the maximum ambient temperatures of 45 °C can be achieved. The results of maximum charging power and limiting ambient temperature give insights for further system improvements which are: sizing of fuel cell or battery trailer design and heat exchanger area operation strategy of the system (power split between high voltage battery and fuel cell) as well as possible dynamic operation scenarios.

The increase in the overall global temperature and its subsequent impact on extreme weather events are the most critical consequences of human activity. In this scenario transportation plays a significant role in greenhouse gas (GHG) emissions which are the main drivers of climate change. The decline of non-renewable energy sources coupled with the aim of reducing GHG emissions from fossil fuels has forced a shift towards a net-zero emissions economy. As an example of this transition the European Union has set 2050 as the target for achieving carbon neutrality. Hydrogen (H2 ) is gaining increasing relevance as one of the most promising carbon-free energy vectors. If produced from renewable sources it facilitates the integration of various alternative energy sources for achieving a carbon-neutral economy. Recently interest in its application to the transportation sector has grown including different power plant concepts such as fuel cells or internal combustion engines. Despite exhibiting significant drawbacks such as low density combustion instabilities and incompatibilities with certain materials hydrogen is destined to become one of the future fuels. In this publication experimental activities are reported that were conducted on a sparkignition engine fueled with hydrogen at different operating points. The primary objective of this research is to gain a better understanding of the thermodynamic processes that control combustion and their effects on engine performance and pollutant emissions. The results show the emission levels performance and combustion characteristics under different conditions of dilution load and injection strategy and timing.

The large-scale deployment of technologies that enable energy from renewables is essential for a successful transition to a carbon-neutral future. While photovoltaic panels are one of the main technologies commonly used for harvesting energy from the Sun storage of renewable solar energy still presents some challenges and often requires integration with additional devices. It is believed that hydrogen – being a perfect energy carrier – can become one of the broadly utilised storage alternatives that would effectively mitigate the energy supply and demand issues associated with the intermittent nature of renewable energy sources. Current pathways in the development of green technologies indicate the need for more sustainable material utilisation and more efficient device operation. To address this requirement integration of various technologies for renewable energy harvesting conversion and storage in a single device appears as an advantageous option. From the hydrogen economy perspective systems driven by green solar electricity that allow for (photo)electrochemical water splitting would generate hydrogen with the minimal CO2 footprint. If at the same time one of the device electrodes could store the generated gas and release it on demand the utilisation of critical and often costly elements would be reduced with possible gain in more effective device operation. Although conceptually attractive this cross-disciplinary concept has not gained yet enough attention and only limited number of experimental setups have been designed tested and reported. This review presents the first exhaustive overview and critical examination of various laboratory-scale prototype setups that attempt to combine both the hydrogen production and storage processes in a single unit via integration of a metal hydride-based electrode into a photoelectrochemical cell. The architectures of presented configurations enables direct solar energy to hydrogen conversion and its subsequent storage in a single device which – in some cases – can also release the stored (hydrogen) energy on demand. In addition this work explores perspectives and challenges related with the potential upscaling of reviewed solar-to-hydrogen storage systems trying to map and indicate the main future directions of their technological development and optimization. Finally the review also combines information and expertise scattered among various research fields with the aim of stimulating much-needed exchange of knowledge to accelerate the progress in the development and deployment of optimum green hydrogen-based solutions.

The ecological transition in the transport sector is a major challenge to tackle environmental pollution and European legislation will mandate zero-emission new cars from 2035. To reduce the impact of petrol and diesel vehicles much emphasis is being placed on the potential use of synthetic fuels including electrofuels (e-fuels). This research aims to examine a levelised cost (LCO) analysis of e-fuel production where the energy source is renewable. The energy used in the process is expected to come from a photovoltaic plant and the other steps required to produce e-fuel: direct air capture electrolysis and Fischer-Tropsch process. The results showed that the LCOe-fuel in the baseline scenario is around 3.1 €/l and this value is mainly influenced by the energy production component followed by the hydrogen one. Sensitivity scenario and risk analyses are also conducted to evaluate alternative scenarios and it emerges that in 84% of the cases LCOe-fuel ranges between 2.8 €/l and 3.4 €/l. The findings show that the current cost is not competitive with fossil fuels yet the development of e-fuels supports environmental protection. The concept of pragmatic sustainability incentive policies technology development industrial symbiosis economies of scale and learning economies can reduce this cost by supporting the decarbonisation of the transport sector.

Grids require electricity storage. Two emerging storage technologies are battery storage (BS) and green hydrogen storage (GHS) (hydrogen produced and compressed with clean-renewable electricity stored then returned to electricity with a fuel cell). An important question is whether GHS alone decreases system cost versus BS alone or BS+GHS. Here energy costs are modeled in 145 countries grouped into 24 regions. Existing conventional hydropower (CH) storage is used along with new BS and/or GHS. A method is developed to treat CH for both baseload and peaking power. In four regions only CH is needed. In five CH+BS is lowest cost. Otherwise CH+BS+GHS is lowest cost. CH+GHS is never lowest cost. A metric helps estimate whether combining GHS with BS reduces cost. In most regions merging (versus separating) grid and non-grid hydrogen infrastructure reduces cost. In sum worldwide grid stability may be possible with CH+BS or CH+BS+GHS. Results are subject to uncertainties.

In this work the design and modeling of a fuel cell vehicle using low-loading platinum catalysts were investigated. Data from single fuel cells with low Pt-loading cathode catalysts were scaled up to fuel cell stacks and systems implemented in a vehicle and then compared to a commercial fuel cell vehicle. The low-loading Pt systems have shown lower efficiency at high loads compared to the commercial systems suggesting less stable materials. However the analysis showed that the vehicle comprising low-loading Pt catalysts achieves similar or higher efficiency compared to the commercial fuel cell vehicle when being scaled up for the same number of cells. When the systems were scaled up for the same maximum power as the commercial fuel cell vehicle all the low-loading Pt fuel cell systems showed higher efficiencies. In this case more cells are needed but still the amount of Pt is significantly reduced compared to the commercial one. The high-efficiency results can be associated with the vehicle’s power range operation that meets the region where the low-loading Pt fuel cells have high performance. The results suggested a positive direction towards the reduction of Pt in commercial fuel cell vehicles supporting a cost-competitive clean energy transition based on hydrogen.

To improve the recovery of waste heat and avoid the problem of abandoning wind and solar energy a multi-energy complementary distributed energy system (MECDES) is proposed integrating waste heat and surplus electricity for hydrogen storage. The system comprises a combined cooling heating and power (CCHP) system with a gas engine (GE) solar and wind power generation and miniaturized natural gas hydrogen production equipment (MNGHPE). In this novel system the GE’s waste heat is recycled as water vapor for hydrogen production in the waste heat boiler while surplus electricity from renewable sources powers the MNGHPE. A mathematical model was developed to simulate hydrogen production in three building types: offices hotels and hospitals. Simulation results demonstrate the system’s ability to store waste heat and surplus electricity as hydrogen thereby providing economic benefit energy savings and carbon reduction. Compared with traditional energy supply methods the integrated system achieves maximum energy savings and carbon emission reduction in office buildings with an annual primary energy reduction rate of 49.42–85.10% and an annual carbon emission reduction rate of 34.88–47.00%. The hydrogen production’s profit rate is approximately 70%. If the produced hydrogen is supplied to building through a hydrogen fuel cell the primary energy reduction rate is further decreased by 2.86–3.04% and the carbon emission reduction rate is further decreased by 12.67–14.26%. This research solves the problem of waste heat and surplus energy in MECDESs by the method of hydrogen storage and system integration. The economic benefits energy savings and carbon reduction effects of different building types and different energy allocation scenarios were compared as well as the profitability of hydrogen production and the factors affecting it. This has a positive technical guidance role for the practical application of MECDESs.

Recently major problems related to fuel consumption and greenhouse gas (GHG) emissions have arisen in the transportation sector. Therefore developing transportation modes powered by alternative fuels has become one of the main targets for car manufacturers and governments around the world. This study aimed to investigate the economic prospects of using hydrogen fuel cell technology in taxi fleets in Westbank. For this purpose a model that could predict the number of taxis was developed and the expected economic implications of using hydrogen fuel cell technology in taxi fleets were determined based on the expected future fuel consumption and future fuel cost. After analysis of the results it was concluded that a slight annual increase in the number of taxis in Palestine is expected in the future due to the government restrictions on issuing new taxi permits in order to get this sector organized. Furthermore using hydrogen fuel cells in taxi fleets is expected to become more and more feasible over time due to the expected future increase in oil price and the expected significant reduction in hydrogen cost as a result of the new technologies that are expected to be used in the production and handling of hydrogen.

Battery electric vehicles (BEVs) and fuel cell electric vehicles (FCEVs) whose exhaust pipes emit nothing are examples of zero-emission automobiles. FCEVs should be considered an additional technology that will help battery-powered vehicles to reach the aspirational goal of zero-emissions electric mobility particularly in situations where the customers demand for longer driving ranges and where using batteries would be insufficient due to bulky battery trays and time-consuming recharging. This study stipulates a current evaluation of the status of development and challenges related to (i) research gap to promote fuel-cell based HEVs (ii) key barriers of fuel-cell based HEVs (iii) advancement of electric mobility and their power drive (iv) electrochemistry of fuel cell technology for FCEVs (v) power transformation topologies communication protocols and advanced charging methods (vi) recommendations and future prospects of fuel-cell HEVs and (vii) current research trends of EVs and FCEVs. This article discusses key challenges with fuel cell electric mobility such as low fuel cell performance cold starts problems with hydrogen storage cost-reduction safety concerns and traction systems. The operating characteristics and applications of several fuel-cell technologies are investigated for FCEVs and FCHEVs. An overview of the fuel cell is provided which serves as the primary source of energy for FCHEVs along with comparisons and its electrochemistry. The study of power transformation topologies communication protocols and enhanced charging techniques for FCHEVs has been studied analytically. Recent technology advancements and the prospects for FCHEVs are discussed in order to influence the future vehicle market and to attain the aim of zero emissions.

The utilisation of hydrogen in ships has important potential in terms of achieving the decarbonisation of waterway transport which produces approximately 3% of the world’s total emissions. However the utilisation of hydrogen drives in maritime and inland shipping is conditioned by the efficient and safe storage of hydrogen as an energy carrier on ship decks. Regardless of the type the constructional design and the purpose of the aforesaid vessels the preferred method for hydrogen storage on ships is currently high-pressure storage with an operating pressure of the fuel storage tanks amounting to tens of MPa. Alternative methods for hydrogen storage include storing the hydrogen in its liquid form or in hydrides as adsorbed hydrogen and reformed fuels. In the present article a method for hydrogen storage in metal hydrides is discussed particularly in a certified low-pressure metal hydride storage tank—the MNTZV-159. The article also analyses the 2D heat conduction in a transversal cross-section of the MNTZV-159 storage tank for the purpose of creating a final design of the shape of a heat exchanger (intensifier) that will help to shorten the total time of hydrogen absorption into the alloy i.e. the filling process. Based on the performed 3D calculations for heat conduction the optimisation and implementation of the intensifier into the internal volume of a metal hydride alloy will increase the performance efficiency of the shell heat exchanger of the MNTZV-159 storage tank. The optimised design increased the cooling power by 46.1% which shortened the refuelling time by 41% to 2351 s. During that time the cooling system which comprised the newly designed internal heat transfer intensifier was capable of eliminating the total heat from the surface of the storage tank thus preventing a pressure increase above the allowable value of 30 bar.

This paper presents a study that focuses on alleviating the impacts of grid outages in Ethiopia. To deal with grid outages most industrial customers utilize backup diesel generators (DG) which are environmentally unfriendly and economically not viable. Grid integration of hybrid renewable energy systems (HRES) might be a possible solution to enhance grid reliability and reduce environmental and economic impacts of utilizing DG. In this study an optimization of grid integrated HRES is carried out for different dispatch and control strategies. The optimal power supply option is determined by performing comparative analysis of the different configurations of grid integrated HRES. The result of the study shows that grid integrated HRES consisting of photovoltaic and wind turbine as renewable energy sources and battery and hydrogen as hybrid energy storage systems is found to be the optimal system to supply the load demand. From the hydrogen produced on-site the FC generator and FCEVs consume 143 620 kg/yr of hydrogen which is equivalent to 394 955 kg/yr gasoline fuel consumption. This corresponds to saving 1 184 865 kg/yr of CO2 emissions and 605 703 $/yr revenue. Besides this system yields 547 035.4 $/yr revenue by injecting excess electricity to the grid. The study clearly shows the economic and environmental viability of this new technology for implementation.

Due to the privileged location of Ecuador in terms of solar radiation the analysis and use of renewable energy system (RES) using solar energy has been of great interest during the last years. At the same time the supply support of RES in terms of direct current (DC) can be faced by using fuel cell (FC) systems which can give to the systems fully autonomy from fossil fuels. The aim of this paper is to propose the design of a hybrid photovoltaic-fuel cell-battery (PV-FC-B) system to supply the required electrical energy for residential use in the city of Guayaquil. The feasibility analysis constitutive elements of the system and adjusted variables are computed and presented using a computational tool. The results evidence that this system is not economically viable since the cost of energy (COE) in Ecuador is low compared to the COE of the proposed system. However a more detailed analysis considering the inherent benefits of no emission of pollutant gases is required to have a complete outlook.

This study represents a thermodynamic evaluation and carbon footprint analysis of the application of hydrogen based energy storage systems in residential buildings. In the system model buildings are equipped with photovoltaic (PV) modules and a hydrogen storage system to conserve excess PV electricity from times with high solar irradiation to times with low solar irradiation. Short-term storages enable a degree of self-sufficiency of approximately 60% for a single-family house (SFH) [multifamily house (MFH): 38%]. Emissions can be reduced by 40% (SFH) (MFH: 30%) compared to households without PV modules. These results are almost independent of the applied storage technology. For seasonal storage the degree of self-sufficiency ranges between 57 and 83% (SFH). The emission reductions highly depend on the storage technology as emissions caused by manufacturing the storage dominate the emission balance. Compressed gas or liquid organic hydrogen carriers are the best options enabling emission reductions of 40%.

Hydrogen-fueled engines require large values of the excess air ratio in order to achieve high thermal efficiency. A low value of this coefficient promotes knocking combustion. This paper analyzes the conditions for the occurrence of knocking combustion in an engine with a turbulent jet ignition (TJI) system with a passive pre-chamber. A single-cylinder engine equipped with a TJI system was running with an air-to-fuel equivalence ratio λ in the range of 1.25–2.00 and the center of combustion (CoC) was regulated in the range of 2–14 deg aTDC (top dead center). Such process conditions made it possible to fully analyze the ascension of knock combustion until its disappearance with the increase in lambda and CoC. Measures of knock in the form of maximum amplitude pressure oscillation (MAPO) and integral modulus of pressure oscillation (IMPO) were used. The absolute values of these indices were pointed out which can provide the basis for the definition of knock combustion. Based on our own work the MAPO index > 1 bar was defined determining the occurrence of knocking (without indicating its quality). In addition taking into account MAPO it was concluded that IMPO > 0.13 bar·deg is the quantity responsible for knocking combustion.

In view of the European Union’s strategy on hydrogen for decarbonization and buildings’ decarbonization targets the use of hydrogen in buildings is expected in the future. Backup power in buildings is usually provided with diesel generators (DGs). In this study the use of a hydrogen fuel cell (HFC) power supply backup system is studied. Its operation is compared to a DG and a techno-economic analysis of the latter’s replacement with an HFC is conducted by calculating relevant key performance indicators (KPIs). The developed approach is presented in a case study on a school building in Greece. Based on the school’s electricity loads which are calculated with a dynamic energy simulation and power shortages scenarios the backup system’s characteristics are defined and the relevant KPIs are calculated. It was found that the HFC system can reduce the annual CO2 emissions by up to 400 kg and has a lower annual operation cost than a DG. However due to its high investment cost its levelized cost of electricity is higher and the replacement of an existing DG is unviable in the current market situation. The techno-economic study reveals that subsidies of around 58–89% are required to foster the deployment of HFC backup systems in buildings.

This paper presents a review of system design and analysis control strategy optimization and heat and mass integration of integrated solid oxide fuel cell (SOFC) and reciprocating internal combustion engine (ICE) system. Facing the future power-fuel-power path both SOFC and ICE can adapt to a variety of fuels which is one evidence that ICE is amenable to integration with SOFC while SOFC is more efficient cleaner and quieter than ICE. Different system topologies are classified whose dynamic performances are also analyzed. In addition the heat and mass integration of system is discussed. Moreover the combustion modes of ICE which can be applied to steady combustion high efficiency and low emissions are analyzed and compared. Meanwhile the potential and methods of system waste heat recovery are discussed. The exergy analysis energy density and techno-economy are discussed. Finally the results are discussed in the last section with the final conclusion that SOFC-ICE systems are very suitable for long-distance transportation such as maritime and aviation which can also solve problems of the carbon and pollutant emissions with the background of engine cannot be replaced in maritime while the system can adapt a variety of alternative fuels.

Within the European Green Deal the European industry is summoned to transform towards a green and circular economy to reduce CO2-emissions and reach climate goals. Special focus is on the chemical industry to boost recycling processes for plastics exploit resource efficiency potentials and switch to a completely renewable feedstock (defossilization). Despite common understanding that drastic changes have to take place it is yet unknown how the industrial transformation should be accomplished. This work explains how a cost-optimal defossilization of the chemical industry in the context of national greenhouse gas (GHG) mitigation strategies look like. The central part of this investigation is based on a national energy system model to optimize the future energy system design of Germany as a case study for a highly industrialized country. A replacement of fossil-based feedstocks by renewable feedstocks leads to a significant increase in hydrogen demand by þ40% compared to a reference scenario. The resulting demand of hydrogen-based energy carriers including the demand for renewable raw materials must be produced domestically or imported. This leads to cumulative additional costs of the transformation that are 32% higher than those of a reference scenario without defossilization of the industry. Fischer-Tropsch synthesis and the methanol-to-olefins route can be identified as key technologies for the defossilization of the chemical industry.

Urban air mobility (UAM) defined as safe and efficient air traffic operations in a metropolitan area for manned aircraft and unmanned aircraft systems is being researched and developed by industry academia and government. This kind of mobility offers an opportunity to construct a green and sustainable sub-sector building upon the lessons learned over decades by aviation. Thanks to their non-polluting operation and simple air traffic management electric vertical take-off and landing (eVTOL) aircraft technologies are currently being developed and experimented with for this purpose. However to successfully complete the certification and commercialization stage several challenges need to be overcome particularly in terms of performance such as flight time and endurance and reliability. In this paper a fast methodology for sizing and selecting the propulsion chain components of an eVTOL multirotor aerial vehicle was developed and validated on a reduced-scale prototype of an electric multirotor vehicle with a GTOW of 15 kg. This methodology is associated with a comparative study of energy storage system configurations in order to assess their effect on the flight time of the aerial vehicle. First the optimal pair motor/propeller was selected using a global nonlinear optimization in order to maximize the specific efficiency of these components. Second five energy storage technologies were sized in order to evaluate their influence on the aerial vehicle flight time. Finally based on this sizing process the optimized propulsion chain gross take-off weight (GTOW) was evaluated for each energy storage configuration using regression-based methods based on propulsion chain supplier data.