Applications & Pathways

This study performed a technical–economic analysis for ship-based ammonia transportation to investigate the feasibility of international ammonia transportation. Ammonia is considered to be a vital hydrogen carrier so the international trade in ammonia by ship will considerably increase in the future. This study proposed three scenarios for transporting ammonia from the USA Saudi Arabia and Australia to South Korea and employed an 84000 m3 class ammonia carrier. Not only traditional very low sulfur fuel oil (VLSFO)/marine diesel oil (MDO) but also LNG and ammonia fuels were considered as propulsion and power generation fuels in the carrier. A life-cycle cost (LCC) model consisting of capital expenditure (CAPEX) and operational expenditure (OPEX) was employed for the cost estimation. The results showed that the transportation costs depend on the distance. The unit transportation cost from the USA to South Korea was approximately three times higher than that of Australia to South Korea. Ammonia fuel yielded the highest costs among the fuels investigated (VLSFO/MGO LNG and ammonia). When using ammonia fuel the unit transportation cost was approximately twice that when using VLSFO/MDO. The fuel costs occupied the largest portion of the LCC. The unit transportation costs from Australia to South Korea were 23.6 USD/ton-NH3 for the LVSFO/MDO fuel case 31.6 USD/ton-NH3 for the LNG fuel case and 42.9 USD/ton-NH3 for the ammonia fuel case. This study also conducted a sensitivity analysis to investigate the influence of assumptions including assumed parameters.

The study of the electrochemical catalyst conversion of renewable electricity and carbon oxides into chemical fuels attracts a great deal of attention by different researchers. The main role of this process is in mitigating the worldwide energy crisis through a closed technological carbon cycle where chemical fuels such as hydrogen are stored and reconverted to electricity via electrochemical reaction processes in fuel cells. The scientific community focuses its efforts on the development of high-performance polymeric membranes together with nanomaterials with high catalytic activity and stability in order to reduce the platinum group metal applied as a cathode to build stacks of proton exchange membrane fuel cells (PEMFCs) to work at low and moderate temperatures. The design of new conductive membranes and nanoparticles (NPs) whose morphology directly affects their catalytic properties is of utmost importance. Nanoparticle morphologies like cubes octahedrons icosahedrons bipyramids plates and polyhedrons among others are widely studied for catalysis applications. The recent progress around the high catalytic activity has focused on the stabilizing agents and their potential impact on nanomaterial synthesis to induce changes in the morphology of NPs.

A form of long-term hydrogen storage with high volume efficiency is hydrogen absorption into the host lattice of a metal or an alloy. Unlike high-pressure hydrogen storage this form of storage is characterised by a low operating pressure. By employing metal hydride (MH) materials in a low-pressure refuelling station it is possible to significantly increase the safety of hydrogen storage and at the same time to facilitate the refuelling of external devices that use MH storage tanks without the necessity of using a compressor. In this article a methodology for the identification of the mathematical correlations among the hydrogen pressure in the storage tank the hydrogen concentration in the alloy and the volumetric flow rate of hydrogen is described. This methodology may be used to identify the kinetics of the process and to create simplified simulations of the hydrogen release from an absorption-based storage tank by applying a finite difference method. The mathematical correlations are based on measurements of hydrogen desorption during which hydrogen was released from the storage tank at stabilised pressure levels. The resulting mathematical description facilitates the identification of the approximate hydrogen pressure depending on its flow rate for a particular MH storage tank while respecting the complexity of its internal structure heat transfer and the hydrogen’s passage through a porous powder MH material. The identified mathematical dependence applies to the certified MNTZV-159 storage tank at pressures ranging from 7 to 29.82 bar with hydrogen concentrations ranging from 0.223 to 1.342% an input temperature of 59.5 ◦C and a cooling water flow rate of 4.36 L·min−1 . This methodology for the identification of a correlation between the flow rate pressure and hydrogen concentration applies to this particular type of storage tank and it depends not only on the alloy used and the quantity of this alloy but also on the internal structure of the heat exchanger.

Green hydrogen is a cornerstone in the global quest for a carbon-neutral future offering transformative potential for decarbonizing transportation. This study investigates its role by assessing the feasibility of a large-scale hydrogen refueling station in Germany focusing on integrating renewable energy sources. A hydrogen demand model with a 10-min time resolution to refuel 30 trucks and 20 vans (1019 kg/day) is combined with a techno-economic optimization model to evaluate a hybrid energy system utilizing wind solar and grid electricity. Scenario-based analysis reveals that Levelized Cost of Hydrogen ranges from 13.92 to 18.12 €/kg primarily influenced by electricity costs. Excess electricity sales can reduce this cost to 13.34–16.92 €/kg. On-site wind energy reduces storage and grid reliance achieving the lowest hydrogen cost. Unlike prior studies this work combines temporally resolved hydrogen demand profiles with comprehensive techno-economic modeling offering unprecedented insights into decentralized green hydrogen systems for heavy-duty transport. By bridging critical gaps in the scalability and economic feasibility of Power-to-Hydrogen systems it provides viable strategies for advancing green hydrogen infrastructure.

The decarbonization of heavy industries demands large volumes of green hydrogen. To produce green hydrogen via electrolysis the EU’s Renewable Energy Directive II imposes rules to ensure the use of renewable electricity. Hydrogen producers can use portfolios of power purchase agreements (PPAs) to buy renewable electricity. These portfolios must meet hydrogen demand cost-effectively and battery storage can help by shifting excess renewable generation. However high uncertainty around future electricity prices and demand complicates optimal portfolio design. Current literature lacks comprehensive models that evaluate such portfolio optimization under uncertainty for real-world case studies including battery storage. This work addresses the gap by introducing a stochastic mixed-integer linear programming model tailored to industrial applications. We demonstrate the model using a real-world glass manufacturing site in Germany. Our findings show that portfolio optimization alone can reduce the levelized cost of hydrogen (LCOH) by 6.24% under EU rules. Adding a battery further cuts costs achieving an LCOH of 11.8 e2024 kg−1 . Exploring different temporal matching schemes reveals that weekly matching reduces LCOH by 2 e2024kg−1 while maintaining a high share of renewable energy. The model offers a flexible tool for optimizing PPA portfolios in various industrial settings.

The present research work investigates the performance of two large-scale energy storage technologies: hydro-pumped storage (HPS) and green hydrogen production within a hybrid renewable energy system (HRES) developed for Kefalonia Island Greece. Given the island’s seasonal water and electricity shortages driven by summer demand and limited infrastructure the goal is to identify which storage option better supports local autonomy. Two scenarios differing only in storage method were simulated using identical wind input and desalination setup. Performance was evaluated based on climate and demand data focusing on water and electricity needs. Both scenarios achieved 99.9 % potable water coverage. The HPS system exhibited notably higher energy efficiency (67 %) compared to hydrogen (33 %) and produced slightly more desalinated water reaching 18157791 m3 versus 17986544 m3 respectively. Electricity demand coverage reached 77.8 % with HPS and 76.0 % with hydrogen while irrigation demand was met by 80.2 % and 79.4 % respectively. Seasonal storage analysis revealed pronounced summer depletion in both cases due to high demand and low wind availability with HPS recovering faster and maintaining higher storage levels owing to lower energy losses. The comparison underscores the need for storage strategies adapted to island-specific water and energy dynamics. HPS is more efficient for short-to-medium-term needs while green hydrogen offers potential for long-duration storage and deeper decarbonization.

Hydrogen-powered unmanned aerial vehicles (UAVs) offer significant advantages such as environmental sustainability and extended endurance demonstrating broad application prospects. However the hydrogen fuel cells face prominent thermal management challenges during flight operations. This study established a numerical model of the fuel cell thermal management system (TMS) for a hydrogen-powered UAV. Computational fluid dynamics (CFD) simulations were subsequently performed to investigate the impact of various design parameters on cooling performance. First the cooling performance of different fan density configurations was investigated. It was found that dispersed fan placement ensures substantial airflow through the peripheral flow channels significantly enhancing temperature uniformity. Specifically the nine-fan configuration achieves an 18.5% reduction in the temperature difference compared to the four-fan layout. Additionally inlets were integrated with the fan-based cooling system. While increased external airflow lowers the minimum fuel cell temperature its impact on high-temperature zones remains limited with a temperature difference increase of more than 19% compared to configurations without inlets. Furthermore the middle inlet exhibits minimal vortex interference delivering superior thermal performance. This configuration reduces the maximum temperature and average temperature by 9.1% and 22.2% compared to the back configuration.

A compact hydrogen supply system for thermally integrating metal hydride (MH) tanks with a proton exchange membrane fuel cell (PEMFC) for a hydrogen-powered electric-assist bicycle (H-bike) is proposed. The system recovers the exhaust heat generated by the PEMFC to sustain hydrogen desorption and improve the system’s energy efficiency. The results demonstrate that the split-tank strategy decreases thermal and pressure gradients and enhances heat transfer and hydrogen release. The honeycomb tank configuration further improves hydrogen desorption by promoting uniform airflow distribution around each tank thereby improving exhaust heat utilization from the PEMFC. It employs a layer-adjustable configuration facilitating the flexible adaptation of MH cartridge quantities to meet hydrogen demand and prevailing road conditions in urban areas. Under a PEMFC power output of 215 W the system maintains a stable hydrogen flow rate for over 30 min with a heat recovery efficiency of 22.62 %. Furthermore increasing the number of MH cartridge layers significantly improves the thermal utilization of the system achieving a utilization efficiency of 39.90 % with two layers. These findings confirm the feasibility and scalability of the proposed system for H-bike highlighting its potential as a decentralized hydrogen supply solution for lightweight mobility and urban transportation applications.

Improving the efficiency and range of hydrogen-powered electric vehicles (HPEVs) is essential for their global adoption especially in developing countries with limited resources. This study systematically evaluates regenerative braking and suspension systems in HPEVs and proposes a deployment-focused framework tailored to the needs of developing nations. A comprehensive search was performed across multiple databases to identify relevant studies. The selected studies are screened assessed for quality and analyzed based on predefined criteria. The data is synthesized and interpreted to identify patterns gaps and conclusions. The findings show that regeneration systems such as regenerative braking and regenerative suspension are the most effective energy recovery systems in most electric and hydrogen-powered vehicles. Although the regenerative braking system (RBS) offers higher energy efficiency gains that enhance cost-effectiveness despite its high initial investment the regenerative suspension system (RSS) involves increased complexity. Still it offers comparatively efficient energy recovery particularly in developing countries with patchy road infrastructure. The gaps highlighted in this review will aid researchers and vehicle manufacturers in designing optimizing developing and commercializing HPEVs for deployment in developing countries.

Solid oxide fuel cells (SOFC) have not received enough attention as a power source in the transportation sector. However with the development of the technology its advantages over other types of fuel cells such as fuel flexibility and high energy efficiency have made SOFC an interesting option. The present study aims at simulation and experimentally validation of the performance of a hydrogen-powered SOFC in an automotive application. A 6 kW SOFC stack is tested and its model is integrated into a series hybrid electric vehicle model. A fuzzy controller is designed to regulate the charging current between the battery and the SOFC in the vehicle model. Experimental tests are also conducted in a few cases on the SOFC based on the simulation results. The performance of the real SOFC stack is then analysed under dynamic loads to see how the desired current is provided in practice. The results demonstrate a good performance of the SOFC stack under variable load conditions.

This paper investigates technological pathways for the conversion of coal-fired power plants toward sustainable energy sources using an integrated multi-criteria decisionmaking approach that combines Proknow-C AHP and PROMETHEE. Eight alternatives were identified: full conversion to natural gas full conversion to biomass coal and natural gas hybridization coal and biomass hybridization electricity and hydrogen cogeneration coal and solar energy hybridization post-combustion carbon capture systems and decommissioning with subsequent reuse. The analysis combined bibliographic data (26 scientific articles and 13 patents) with surveys from 14 energy experts using Total Decision version 1.2.1041.0 and Visual PROMETHEE version 1.1.0.0 software tools. Based on six criteria (environmental structural technical technological economic and social) the most viable option was full conversion to natural gas (ϕ = +0.0368) followed by coal and natural gas hybridization (ϕ = +0.0257) and coal and solar hybridization (ϕ = +0.0124). These alternatives emerged as the most balanced in terms of emissions reduction infrastructure reuse and cost efficiency. In contrast decommissioning (ϕ = −0.0578) and carbon capture systems (ϕ = −0.0196) were less favorable. This study proposes a structured framework for strategic energy planning that supports a just energy transition and contributes to the United Nations Sustainable Development Goals (SDGs) 7 and 13 highlighting the need for public policies that enhance the competitiveness and scalability of sustainable alternatives.

The development of hydrogen refueling infrastructure plays a strategic role in enabling the decarbonization of the transport sector especially along major freight and passenger corridors such as the Trans-European Transport Network (TEN-T). Despite the growing interest in hydrogen mobility existing methodologies for the optimal location of hydrogen refueling stations (HRS) remain fragmented and often overlook operational dynamics. Following a review of the existing literature on HRS location models and approaches this study highlights key methodological gaps that hinder effective infrastructure planning. In response a two-stage framework is proposed combining a flow-based location model with a stochastic queueing approach to determine both the optimal placement of HRS and the number of dispensers required at each site. The method is applied to a real segment of the TEN-T network in Northern Italy. The results demonstrate the flexibility of the model in accommodating different hydrogen vehicle penetration scenarios and its utility as a decision-support tool for public authorities and infrastructure planners.

Direct electrification and hydrogen utilization represent two key pathways for decarbonizing the glass industry with their effectiveness subject to adequate furnace design and renewable energy availability. This study presents a techno-economic assessment for optimal solar energy integration in a representative 300 t/d oxyfuel container glass furnace with a specific energy consumption of 4.35 GJ/t. A mixed-integer linear programming formulation is developed to evaluate specific melting costs carbon emissions and renewable energy self-consumption and self-production rates across three scenarios: direct solar coupling battery storage and a hydrogen-based infrastructure. Battery storage achieves the greatest reductions in specific melting costs and emissions whereas hydrogen integration minimizes electricity export to the grid. By incorporating capital investment considerations the study quantifies the cost premiums and capacity requirements under varying decarbonization targets. A combination of 30 MW of solar plant and 9 MW of electric boosting enables the realization of around 30% carbon reduction while increasing total costs by 25%. Deeper decarbonization targets require more advanced systems with batteries emerging as a cost-effective solution. These findings offer critical insights into the economic and environmental trade-offs as well as the technical constraints associated with renewable energy adoption in the glass industry providing a foundation for strategic energy and decarbonization planning.

Hydrogen-powered aircraft as a cutting-edge exploration of clean-energy air transportation have more stringent requirements for lightweight hydrogen storage equipment due to the limitations of aircraft weight and volume. Composite hydrogen storage cylinders have become one of the preferred solutions for hydrogen storage systems in hydrogen-powered aircraft due to their light weight and high strength. However during the automated placement of high-stiffness thermoplastic composites (T700/PEEK) fibers can buckle or fracture in the header section. As the header radius decreases the overlap of adjacent tows increases resulting in buildup in the thickness of the polar pores which contradicts the lightweight requirements. To solve this problem this paper derives the trajectory algorithm as a manufacturing process limitation when thermoplastic fiber bundles are laid without wrinkles and the effect of different ellipsoid ratios of head profile changes on the overlap of fiber bundles is investigated. The larger the ellipsoid ratio of the prolate ellipsoid is the smaller overlap of gaps generated by neighboring fiber bundles is and the overlap at the pole holes is also smaller whereas the change of the oblate ellipsoid is not significant. The prolate ellipsoid has more application and research value than the oblate ellipsoid in terms of processability which is of great exploration significance for the design and fabrication of thermoplastic composite hydrogen storage cylinders for hydrogen-powered aircraft.

Infrastructure and processes for handling liquid hydrogen (LH2) is needed to decarbonize aviation with hydrogen aircraft. Large airports benefit from pipeline refuelling systems which must be operated to keep the fuel subcooled due to LH2 vaporization challenges. In this paper we estimate LH2 demand for aircraft and the gaseous H2 demand for ground support equipment (GSE) at Schipol in 2050. Modelling and simulation of aircraft refuelling via pipelines show that continuous LH2 recycling is required to maintain subcooling. Vaporization of LH2 during refuelling is heavily influenced by pipeline temperatures. Refuelling aircraft in the morning causes the highest vaporization (2.2 %) due to a long period with low LH2 flow (no refuelling at night). The vaporization decreases to 0 % throughout the day. Furthermore increasing the recycle rate during night lowers the pipeline temperatures reducing the vaporization to 1.7 %. The amount of vaporized hydrogen corresponds well with the GSE demand for gaseous H2.

The recovery of energy and valuable compounds from exhaust gases in the iron and steel industry deserves specialattention due to the large power consumption and CO 2 emissions of the sector. In this sense the hydrogen content of coke oven gas(COG) has positioned it as a promising source toward a hydrogen-based economy which could lead to economic and environmentalbenefits in the iron and steel industry. COG is presently used for heating purposes in coke batteries or furnaces while in highproduction rate periods surplus COG is burnt in flares and discharged into the atmosphere. Thus the recovery of the valuablecompounds of surplus COG with a special focus on hydrogen will increase the efficiency in the iron and steel industry compared tothe conventional thermal use of COG. Different routes have been explored for the recovery of hydrogen from COG so far: i)separation/purification processes with pressure swing adsorption or membrane technology ii) conversion routes that provideadditional hydrogen from the chemical transformation of the methane contained in COG and iii) direct use of COG as fuel forinternal combustion engines or gas turbines with the aim of power generation. In this study the strengths and bottlenecks of themain hydrogen recovery routes from COG are reviewed and discussed.

The purpose of this study is to analyze and compare the techno-economic performance of grid-connected Hybrid Energy Systems (HES) consisting of Photovoltaic (PV) and Reformer Fuel-Cell (RF-FC) using different types of solar PV tracking techniques to supply electricity to a small location in the City of Chlef Algeria. The PV tracking systems considered in this study include fixed facing south at four different angles (32◦ 34◦ 36◦ 38◦) horizontal-axis with continuous adjustment vertical-axis with continuous adjustment and a two-axis tracking system. The software tool HOMER Pro (Hybrid Optimization of Multiple Energy Resources) is used to simulate and analyze the technical feasibility and life-cycle cost of these different configurations. The meteorological data consisting of global solar radiation and air temperature used in this study was collected from the geographical area of the City of Chlef during the year 2020. This study has shown that the optimal design of a grid-connected hybrid PV/RF-FC energy system with Vertical Single Axis Tracker (VSAT) leads to the best economic perfor mance with low values of Net Present Cost (NPC) Cost of Energy (COE) with a Positive Return on Investment (ROI) and the shortest Simple Payback (SP) period. In addition from the simulation results obtained it can be concluded that the Horizontal and Vertical Single-Axis Trackers (HSAT and VSAT) as well as the Dual-Axis Tracker (DAT) are not always cost effective compared to the Fixed Tilt System (FTS). Therefore it is neces sary to carefully analyze the use of each tracker to assess whether the energy gain achieved outweighs the overall shortcomings of the tracker.

The growing penetration of renewable energy sources requires resilient microgrids capable of providing stable and continuous operation. Hybrid energy storage systems (HESS) which integrate hydrogen-based storage systems (HBSS) battery storage systems (BSS) and supercapacitor banks (SCB) are essential to ensuring the flexibility and robustness of these microgrids. Accurate modelling of these microgrids is crucial for analysis controller design and performance optimization but the complexity of HESS poses a significant challenge: simplified linear models fail to capture the inherent nonlinear dynamics while nonlinear approaches often require excessive computational effort for real-time control applications. To address this challenge this study presents a novel state space model with linear variable parameters (LPV) which effectively balances accuracy in capturing the nonlinear dynamics of the microgrid and computational efficiency. The research focuses on a high-voltage DC bus microgrid architecture in which the BSS and SCB are connected directly in parallel to provide passive DC bus stabilization a configuration that improves system resilience but has received limited attention in the existing literature. The proposed LPV framework employs recursive linearisation around variable operating points generating a time-varying linear representation that accurately captures the nonlinear behaviour of the system. By relying exclusively on directly measurable state variables the model eliminates the need for observers facilitating its practical implementation. The developed model has been compared with a reference model validated in the literature and the results have been excellent with average errors MAE RAE and RMSE values remaining below 1.2% for all critical variables including state-of-charge DC bus voltage and hydrogen level. At the same time the model maintains remarkable computational efficiency completing a 24-h simulation in just 1.49 s more than twice as fast as its benchmark counterpart. This optimal combination of precision and efficiency makes the developed LPV model particularly suitable for advanced model-based control strategies including real-time energy management systems (EMS) that use model predictive control (MPC). The developed model represents a significant advance in microgrid modelling as it provides a general control-oriented approach that enables the design and operation of more resilient efficient and scalable renewable energy microgrids.

Indonesia faces mounting challenges from climate change and environmental degradation underscoring the need for sustainable transportation solutions. This study evaluates factors influencing the adoption of Hybrid Electric Vehicles (HEV) Battery Electric Vehicles (BEV) and Hydrogen Fuel Cell Vehicles (HFCV) using Multi-Criteria Analysis (MCA) and Total Cost of Ownership (TCO) approaches. Eight key factors were analyzed: safety operational and maintenance costs initial cost government incentives charging speed resale value and environmental impact. Findings reveal that safety concerns particularly for hydrogen vehicles rank as the highest priority for consumers followed by cost efficiency and government support. Environmental considerations while significant were lower in priority. The study highlights the importance of targeted subsidies enhanced safety features and infrastructure investments to overcome barriers to adoption. By providing actionable recommendations such as raising public awareness of the long-term benefits of environmentally friendly vehicles this research supports policymakers in driving the transition to sustainable transportation in Indonesia. These insights contribute to addressing rising vehicle emissions and fostering the adoption of HEV5 BEV2 and HFCV6 aligning with Indonesia’s broader climate goals.

The combustion of pure H2 in engines is still troublesome needing further research and development. Using H2 and diesel in a dual-fuel compression ignition engine appears as a more feasible approach. Here we report an experimental assessment of performance and emissions for a single-cylinder four-stroke air-cooled compression ignition engine operating with neat diesel and H2-diesel dual-fuel. Previous studies typically show the performance and emissions for a specific operation condition (i.e. a fixed engine speed and torque) or a limited operating range. Our experiments covered engine speeds of 3000 and 3600 rpm and torque levels of 3 and 7 Nm. An in-house designed and built alkaline cell generated the H2 used for the partial substitution of diesel. Compared with neat diesel the results indicate that adding H2 decreased the air-fuel equivalence ratio and the Brake Specific Diesel Fuel Consumption Efficiency by around 14–29 % and 4–31 %. In contrast adding H2 increased the Brake Fuel Conversion Efficiency by around 3–36 %. In addition the Brake Thermal Efficiency increased in the presence of H2 in the range of 3–37 % for the lower engine speed and 27–43 % for the higher engine speed compared with neat diesel. The dual-fuel mode resulted in lower CO and CO2 emissions for the same power output. The emissions of hydrocarbons decreased with H2 addition except for the lower engine speed and the higher torque. However the dual-fuel operation resulted in higher NOx emissions than neat diesel with 2–6 % and 19–48 % increments for the lower and higher engine speeds. H2 emerges as a versatile energy carrier with the potential to tackle current energy and emissions challenges; however the dual-fuel strategy requires careful management of NOx emissions.

This study evaluates the effects of adding a hydrogen gaseous mixture (HGM) to primary fuel in a single cylinder research engine (SCRE). Storage and transportation of high-purity hydrogen limit the application of this gas. With the development of fuel reforming methods using hydrogenenriched mixtures in spark-ignited internal combustion engines is a convenient option to fossil fuels. Ethanol and gasoline were used as primary fuel by direct injection (DI) and gaseous mixture was added by fumigation system (FS). The experimental analysis was developed in Spark Ignition (SI) four-stroke engine 4 valves and 0.45 L of cubic capacity. For each operation condition and primary fuel spark timing and amount of HGM were adjusted in order to keep air-fuel ratio stochiometric (λ = 100). However the spark timing and the percentage of gas varied aiming to evaluate the behavior of the air-fuel mixture. It was evaluated the specific fuel consumption and the evolution of the combustion process. The results showed that the addition of reformed gas promotes acceleration of the combustion process ethanol and gasoline. Results were expressive when using ethanol. A reduction in fuel-specific consumption - for this fuel - with combustion centralized which did not occur when gasoline was employed.

The production of iron and steel plays a significant role in the anthropogenic carbon footprint accounting for 7% of global GHG emissions. In the context of CO2 mitigation the steelmaking industry is looking to potentially replace traditional carbon-based ironmaking processes with hydrogen-based direct reduction of iron ore in shaft furnaces. Before industrialization detailed modeling and parametric studies were needed to determine the proper operating parameters of this promising technology. The modeling approach selected here was to complement REDUCTOR a detailed finite-volume model of the shaft furnace which can simulate the gas and solid flows heat transfers and reaction kinetics throughout the reactor with an extension that describes the whole gas circuit of the direct reduction plant including the top gas recycling set up and the fresh hydrogen production. Innovative strategies (such as the redirection of part of the bustle gas to a cooling inlet the use of high nitrogen content in the gas and the introduction of a hot solid burden) were investigated and their effects on furnace operation (gas utilization degree and total energy consumption) were studied with a constant metallization target of 94%. It has also been demonstrated that complete metallization can be achieved at little expense. These strategies can improve the thermochemical state of the furnace and lead to different energy requirements.

Hydrogen-enriched compressed natural gas (HCNG) holds significant promise for renewable energy absorption and hydrogen utilization while also increasing the complexity of Integrated Energy System (IES) structures which presents challenges for optimal HCNG-IES operation. Energy inertia provides IES with potential operational flexibility. However existing HCNG-IES optimization technologies inadequately account for hydrogen and thermal inertia leaving significant opportunities to enhance system performance. In this study we begin with a comprehensive analysis and modeling of the hydrogen-thermal multi-energy inertia (HTMEI) processes which encompass the hydrogen inertia of HCNG loads and hydrogen storage tanks as well as the thermal inertia of thermal storage tanks and buildings. Following this we develop an optimization model for the operation of HCNG-IES that incorporates HTMEI to optimize the system's overall performance in terms of economic environmental and energy efficiency criteria. The resulting optimal scheduling scheme integrates the outputs of energy devices and multi-energy inertia processes. Case studies validate the efficacy of the proposed operational optimization method. The results indicate that in comparison with an operational optimization method that does not consider energy inertia the proposed approach reduces operational costs by 34.79% carbon emissions by 32.93% electricity purchased from the grid by 95.37% and natural gas consumption by 11.8%. Furthermore the analysis has verified the mutual enhancement between hydrogen inertia and thermal inertia along with their positive individual impacts on operational performance of the HCNGIES.

This study investigates the interactive dynamics of directly injected (DI) hydrogen and methane jets with wall and neighboring jets in a non-reactive environment focusing on the influence of wave-shaped piston geometry. Experiments were conducted in a high-pressure optical chamber using a custom 2-hole DI injector with Schlieren imaging employed to capture the temporal evolution of jet structures for varying injection durations and injection pressure ratios. Comparative analyses between conventional flat and wave-shaped wall geometries reveals that the wave geometry significantly alters post-impingement jet behavior particularly enhancing jet guidance toward the center and promoting early detachment from the wall. For both hydrogen and methane jets impinging on the wave wall exhibited accelerated formation of a central flow structure akin to the radial mixing zone (RMZ) observed in reactive diesel combustion. This effect was most pronounced after end of injection where the trailing edge of the impinged jets in the wave geometry detached earlier and exhibited inward momentum forming U-shaped flow patterns indicative of efficient mixing. Quantitative jet area analysis further showed that the wave geometry confined and redirected the jets more effectively than the flat wall especially for hydrogen at shorter injection durations. These results demonstrate that the wave-piston concept originally developed for soot reduction in diesel engines also enhances jet-jet and jet-wall interaction efficiency in gaseous DI systems by promoting structured recirculation. Moreover these results suggest that wave-based piston geometries can substantially influence fuel-air mixing dynamics even in the absence of combustion providing a foundation for optimizing combustion chamber designs for low-carbon and high-diffusive gaseous fuels.

This work describes a thermodynamic comparison of the thermal efficiency of gas turbine engines featuring a conventional combustion chamber and a detonation combustion chamber using methane ethanol and mixtures of both ethanol and hydrogen and methane and hydrogen as fuels. The composition of gases was determined by the minimization of the Gibbs free energy whereas temperature pressure and velocity of detonation waves were determined by the Chapman-Jouguet theory. The results obtained here show that the DCC gas turbine cycle has a higher net work output and thermal efficiency than the CCC gas turbine cycle for all fuels studied in this work. The maximum thermal efficiency obtained with the DCC gas turbine cycle is indeed 57.22% which represents a 53.75% improvement over the maximum thermal efficiency obtained with the CCC gas turbine cycle (which has a peak thermal efficiency of 37.22%) under the same pressure ratio and turbine inlet temperature.