Publications

Given the rising interest in hydrogen economy alternative feedstocks are explored for their potential use for hydrogen production such as H2S a notable byproduct from oil and gas operations. This study presents a computational investigation on the thermodynamics kinetics and mechanisms of non-catalytic H2S-steam reforming (H2SSR) as a pathway for H2S-to-H2 benchmarked to H2S thermal decomposition (H2SPyrol) (as a limiting case without water). The mechanism integrates key elementary steps form different reaction pathways including H2S partial oxidation H2O reduction and H2S thermal decomposition. Results from the model are validated using available experimental data for H2SPyrol and H2SSR. Homogeneous gas-phase reactions are modelled at different H2O:H2S ratios reaction temperatures pressure and times. Thermodynamically the H2SSR reaction is unfavorable due to the presence of water and its role in increasing the reaction complexity and endothermicity; however kinetically water contributes to increasing the hydrogen yield at least 9 times that from H2SPyrol achieving 99.23 % H2S conversion at 1473 K with an excess H2O:H2S feed ratio of 200:1. The contribution of water during the H2SSR reaction is interpreted using reaction path and rate of production analyses demonstrating its role in producing an abundant pool of OH and H radicals. These radicals catalyze the cleavage of H2S-SH bonds accelerating hydrogen production at an optimal reaction time of 0.07–0.105 s. This study paves the path for future kinetic and catalytic research to optimize the technical viability of H2SSR as a promising H2S-to-H2 conversion pathway for sour wastewater reutilization.

The hydrogen economy stands at the forefront of the global energy transition and additive manufacturing (AM) is increasingly recognized as a critical enabler of this transformation. AM offers unique capabilities for improving the performance and durability of hydrogen energy components through rapid prototyping topology optimization functional integration of cooling channels and the fabrication of intricate hierarchical structured pores with precisely controlled connectivity. These features facilitate efficient heat and mass transfer thereby improving hydrogen production storage and utilization efficiency. Furthermore AM’s multi-material and functionally graded printing capability holds promise for producing components with tailored properties to mitigate hydrogen embrittlement significantly extending operational lifespan. Collectively these advances suggest that AM could lower manufacturing costs for hydrogen-related systems while improving performance and reliability. However the current literature provides limited evidence on the integrated techno-economic advantages of AM in hydrogen applications posing a significant barrier to large-scale industrial adoption. At present the technological readiness level (TRL) of AM-based hydrogen components is estimated to be 4–5 reflecting laboratory-scale progress but underscoring the need for further development validation and industrial-scale demonstration before commercialization can be realized.

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.

The carbon-neutral and carbon-negative energy utilization technologies have long been people pursued to realize the strategic objective of carbon neutrality. Herein we propose a cation-exchange membrane (CEM) direct formate-CO2 fuel cell that possesses the capability of simultaneously generating electricity and producing hydrogen as well as continuously transforming carbon dioxide into pure sodium bicarbonate. Using the CO2- derived formate fuel the roof-of-concept CEM direct formate-CO2 fuel cell exhibits a peak power density of 38 mW cm− 2 at 80 ◦C without the assistance of additional electrolyte. The fairly stable constant-current discharge curve along with the detected hydrogen and pure sodium bicarbonate prove the conceptual feasibility of this electricity‑hydrogen-bicarbonate co-production device. By adding alkaline electrolyte to the anode we achieved a higher peak power density of 63 mW cm− 2 at the corresponding hydrogen production rate of 0.57 mL min− 1 cm− 2 . More interestingly the concentrations of pure NaHCO3 solution can be controlled by adjusting the cathode water flow rate and fuel cell discharge current density. This work presents a theoretically feasible avenue for coupling hydrogen production and CO2 utilization.

This study conducts a thorough review of fuel cell technology including types economy applications and V2G scheme. Fuel cells have been considered for diverse applications namely electric vehicles specialty vehicles such as warehouse forklifts public transportation including buses trains and ferries. Other applications include grid-related stationary and portable applications. Among available five types of fuel cells PEMFC is presently the optimal choice for electric vehicle usage due to its low operating temperature and durability. Meanwhile high temperature fuel cells such as MCFC and SOFC currently remain the best choice for utility and grid related applications. The economy of fuel cells has been continuously improving and has been illustrated to only grow into a potential main source of sustainable energy soon. With the transportation sector as fuel cell electric ve hicles evolve V2G technology is beneficial towards energy efficiency and fuel cell economy. There is evidence for V2G using FCEV being more advantageous in comparison to conventional BEVs. The costs of the five types of fuel cell vary from US$1784 to US$4500 per kW capacity. The findings are beneficial for researchers and industry professionals who wish to gain comprehensive understanding of fuel cells for adoption and development of the emerging low-emission energy solutions.

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.

We develop a bidding strategy for a hybrid power plant combining co-located wind turbines and an electrolyzer constructing a price-quantity bidding curve for the day-ahead electricity market while optimally scheduling hydrogen production. Without risk management single imbalance pricing leads to an all-or-nothing trading strategy which we term “betting”. To address this we propose a data-driven pragmatic approach that leverages contextual information to train linear decision policies for both power bidding and hydrogen scheduling. By introducing explicit risk constraints to limit imbalances we move from the all-or-nothing approach to a “trading” strategy where the plant diversifies its power trading decisions. We evaluate the model under three scenarios: when the plant is either conditionally allowed always allowed or not allowed to buy power from the grid which impacts the green certification of the hydrogen produced. Comparing our data-driven strategy with an oracle model that has perfect foresight we show that the risk-constrained data-driven approach delivers satisfactory performance.

This study presents a hybrid power system comprising a fuel cell (FC) and a lithium-ion battery (LIB) for liquid hydrogen (LH2) carriers which is expected to increase globally due to the production cost gap of green hydrogen between renewable-rich and renewable-poor countries. The LH2 carrier has a key challenge in handling the inevitably considerable boil-off hydrogen (BOH). As a target ship of a 50000 m3 LH2 carrier with a boil-off rate (BOR) of 0.4% per day this study employs an optimization tool to determine the economic power dispatch between the FC and LIB aimed at minimizing the lifetime cost of the ship. The BOH is used as fuel for FC during the voyage. Moreover when the ship is under cargo loading and unloading operations at the port the considerable surplus BOH is utilized to generate electricity and then sold to the shore grid (StG). The results indicate that 45.2% of the BOH can be utilized as fuel for the FC and the StG system can effectively reduce the total lifetime cost by 32.0%. Further the paper presents the outcomes of a sensitivity analysis conducted on critical parameters. This study provides new insights into the BOH issue of LH2 carriers and helps to increase the international green hydrogen market.

Recent studies on additive manufacturing (AM) have indicated the necessity of understanding the hydrogen embrittlement (HE) of high-strength steels fabricated by AM due to the different microstructure obtained compared to their conventionally processed counterparts. This study investigated the influence of post-AM tempering (at 205 ◦C 315 ◦C and 425 ◦C) on the HE resistance of AM-fabricated AISI 4340 steel a representative ultrahigh-strength medium-carbon low-alloy steel. The present results show that tempering effectively reduced the HE sensitivity of the steel. When tested in air tempering at a low temperature of 205 ◦C slightly increased both the yield strength (YS) and ultimate tensile strength (UTS) accompanied by a reduction in elongation (EL). This behaviour is attributed to the precipitation of carbides. In contrast higher tempering temperatures of 315 ◦C and 425 ◦C resulted in a progressive decrease in both YS and UTS as anticipated. However when tested in a hydrogen-rich environment although the HE dramatically reduced the ductility and YS could not even be determined for the samples tempered at 205 ◦C and 315 ◦C the tempered samples retained higher UTS and EL compared to the as-AM-fabricated samples because of the increased HE resistance by tempering. Microstructural examination indicated that tempering at 205 ◦C and 315 ◦C retained the bainitic microstructure while promoting the formation of fine carbide precipitates which softened the bainitic ferrite matrix enhancing the hydrogen trapping capacity. Tempering at 425 ◦C promoted recovery of the AM-fabricated steel reducing dislocation density producing a lower subsurface hydrogen concentration and higher hydrogen diffusivity which led to an enhanced HE resistance. As a result testing of the samples tempered at 425 ◦C in hydrogen resulted in a high YS (~1200 MPa) and only a ~5 % reduction in UTS and a 64 % reduction in EL compared with the untempered samples of which the reductions were 31 % in UTS and 79 % in EL. Furthermore this study underscores the critical role of the trap character in governing the HE behaviour offering a pathway toward optimised heat treatment strategies for improved HE resistance of additively manufactured high-strength steels.

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.