Applications & Pathways

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.