Turkey

In this study a novel thermo-economic analysis on a membrane reactor adopted to generate hydrogen coupled to a carbon-dioxide capture system is proposed. Exergy destruction fuel and environmental as well as pur chased equipment costs have been accounted to estimate the cost of hydrogen production in the aforementioned integrated plant. It has been found that the integration of the CO2 capture system with the membrane reactor is responsible for the reduction of the hydrogen production cost by 12 % due to the decrease in environmental penalty cost. In addition the effects of operating parameters (steam-to-carbo ratio and biogas temperature) on the hydrogen production cost are investigated. Hence this work demonstrates that the latter can be decreased by approximately 2 $/kgH2 when steam to carbon ratio increases from 1.5 to 4. The analyses reveal that steam-tocarbo ratio increases exergy destruction cost affecting consequently also the hydrogen production cost. How ever from a thermodynamic point of view it enhances the hydrogen production in the membrane reactor mutually lowering the hydrogen production cost. It has been also estimated that a decrease in the biogas inlet temperature from 450 to 400◦C can reduce the hydrogen production cost by 7 %. This study demonstrates that the fuel cost is a major economic parameter affecting commercialization of hydrogen production while exergy destruction and environmental costs are also significant factors in determining the hydrogen production cost.

The shipping industry remains heavily dependent on heavy fuel oils which account for approximately 77% of fuel consumption and contribute significantly to greenhouse gas (GHG) emissions. In line with the IMO’s decarbonization targets ammonia has emerged as a promising carbon-free alternative. This study evaluates the strategic viability of ammonia especially green production as a marine fuel through a hybrid SWOT–Best–Worst Method (BWM) analysis combining literature insights with expert judgment. Data were collected from 17 maritime professionals with an average of 15.7 years of experience ensuring robust sectoral representation and methodological consistency. The results highlight that opportunities hold the greatest weight (0.352) particularly the criteria “mandatory carbonfree by 2050” (O3:0.106) and “ammonia–hydrogen climate solution” (O2:0.080). Weaknesses rank second (0.270) with “higher toxicity than other marine fuels” (W5:0.077) as the most critical concern. Strengths (0.242) underscore ammonia’s advantage as a “carbonfree and sulfur-free fuel” (S1:0.078) while threats (0.137) remain less influential though “costly green ammonia” (T3:0.035) and “uncertainty of green ammonia” (T1:0.034) present notable risks. Overall the analysis suggests that regulatory imperatives and environmental benefits outweigh safety technical and economic challenges. Ammonia demonstrates strong potential to serve as viable marine fuel in achieving the maritime sector’s long-term decarbonization goals.

The transportation sector is a significant contributor to global carbon emissions thus necessitating a transition toward renewable energy sources (RESs) and electric vehicles (EVs). Among EV technologies fuel-cell EVs (FCEVs) offer distinct advantages in terms of refueling time and operational efficiency thus rendering them a promising solution for sustainable transportation. Nevertheless the integration of FCEVs in rural areas poses challenges due to the limited availability of refueling infrastructure and constraints in energy access. In order to address these challenges this study proposes a multi-objective energy management model for a hydrogen refueling station (HRS) integrated with RESs a battery storage system an electrolyzer (EL) a fuel cell (FC) and a hydrogen tank serving diverse FCEVs in rural areas. The model formulated using mixed-integer linear programming (MILP) optimizes station operations to maximize both cost and load factor performance. Additionally bi-directional trading with the power grid and hydrogen network enhances energy flexibility and grid stability enabling a more resilient and self-sufficient energy system. To the best of the authors’ knowledge this study is the first in the literature to present a multi-objective optimal management approach for grid-interactive renewablesupported HRSs serving hydrogen-powered vehicles in rural areas. The simulation results demonstrate that RES integration improves economic feasibility by reducing costs and increasing financial gains while maximizing the load factor enhances efficiency cost-driven strategies that may impact stability. The impact of the EL on cost is more significant while RES capacity has a relatively smaller effect on cost. However its influence on the load factor is substantial. The optimization of RES-supported hydrogen production has been demonstrated to reduce external dependency thereby enabling surplus trading and increasing financial gains to the tune of USD 587.83. Furthermore the system enhances sustainability by eliminating gasoline consumption and significantly reducing carbon emissions thus supporting the transition to a cleaner and more efficient transportation ecosystem.

Polymer Electrolyte Membrane Water Electrolyzers (PEMWEs) attract significant attention for producing green hydrogen. However their widespread application remains hindered by high production costs. This study develops cost-effective and high-performance 3D-printed gyroid structures as porous transport layers (PTLs) for the anode of PEMWEs. Experimental results demonstrate that the PTL’s structure critically influences its performance which depends on its design. Among the four gyroid structures evaluated the G10 electrode exhibited the best performance in electrochemical tests conducted under various ex-situ conditions simulating real-world operation. Furthermore the 3D-printed G10 electrode undergoes Pt coating and is compared with commercially available PTLs. The commercial PTL (C3) shows a current density of 138.488 mA cm−2 whereas the G10-1.00 μm Pt electrode achieves a significantly higher current density of 584.692 mA cm−2 at 1.9V. The gyroid structure is a promising avenue for developing high-energy and low-cost PEMWEs and other related technologies.

The use of rare earth elements in hydrogen storage processes offers significant advantages in terms of increasing technological efficiency and ensuring system security. However this process also creates some serious problems in terms of environmental and economic sustainability. It is necessary to determine the most critical indicators affecting the sustainable use of these elements. Studies on this subject in the literature are quite limited and this may lead to wrong investment decisions. The main purpose of this study is to determine the most important indicators to increase the sustainable use of rare earth elements in hydrogen storage processes. An original decision-making model in which Siamese network logarithmic percentage-change driven objective weighting (LOPCOW) fractal fuzzy numbers and weighted influence super matrix with precedence (WISP) approaches are integrated in the study. This study provides an original contribution to the literature by identifying the most critical indicators affecting the sustainable use of rare earths in hydrogen storage processes by presenting an innovative model. Fractal structures such as Koch Snowflake Cantor Dust and Sierpinski Triangle can model complex uncertainties more successfully. Fractal structures are particularly effective in modeling linguistic fuzziness because their recursive nature closely mirrors the layered and imprecise way humans often express subjective judgments. Unlike linear fuzzy sets fractals can capture the patterns of ambiguity found in expert evaluations. Hydrogen storage capacity and government supports are determined as the most vital criteria affecting sustainability in rare earth use.

The transition to a low-carbon energy future requires a multi-faceted approach including the enhancement of existing power generation technologies. This study provides a comprehensive experimental evaluation of hydrogen enrichment as a strategy to improve the performance and reduce the emissions of a power generator. A 3.65 kW power generator that is equipped with spark-ignition engine is systematically tested with five distinct base fuels: gasoline propane methane ethanol and methanol. Each fuel is volumetrically blended with pure hydrogen in ratios of 5 % 10 % 15 % and 20 % using a custom-developed dual-fuel carburetor. The key parameters including exhaust emissions (CO2 CO HC NOx) cylinder exit temperature electrical power output and thermodynamic efficiencies (energy and exergy) are meticulously measured and analyzed. The results reveal that hydrogen enrichment is a powerful tool for decarbonization consistently reducing carbon-based emissions across all fuels. At a 20 % hydrogen blend CO2 emissions are reduced by 22–31 % CO emissions by 39–60 % and HC emissions by 21–60 %. This environmental benefit however is accompanied by a critical trade-off: a severe increase in NOx emissions which rose by 200–420 % due to significantly elevated combustion temperatures. The power outputs are increased by 2–16 % with hydrogen addition enabling lower-energy–density fuels like methane and propane to achieve performance parity with gasoline. Thermodynamic analysis confirms these gains with energy efficiency showing marked improvement particularly for methane which has increased from 42.0 % to 49.9 %. While hydrogen enrichment presents a viable pathway for enhancing engine performance and reducing the carbon emissions of power generators the profound increase in NOx necessitates the integration of advanced control and after-treatment systems for its practical and environmentally responsible deployment.