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.