Publications

Green hydrogen is essential for advancing the energy transition as it is regarded as a CO2-neutral flexible and storable energy carrier. Particularly in steel production which is known for its high energy intensity hydrogen has great potential to replace conventional energy sources. In a game-theoretic bi-level optimization model involving a power plant operator and a steel company we investigate in which situations the production and use of green hydrogen is advantageous from an economic and ecological point of view. Through an extensive case study based on a realworld scenario we can observe that hydrogen production can serve as a profitable and flexible secondary income opportunity for the power plant operator and help avoid curtailment and spot market losses. On the other hand the steel manufacturer can reduce CO2 emissions and associated costs while also meeting the growing customer demand for low-carbon products. However our findings also highlight important trade-offs and uncertainties. While lower electricity generation costs or improved electrolyzer efficiency enhance hydrogen’s competitiveness increases in coal and CO2 emission prices do not always result in greater hydrogen adoption. This is due to the persistent reliance on a non-replaceable share of coal in steel production which raises the overall cost of both low-carbon and carbon-intensive steel. The model further shows that consumer demand elasticity plays a critical role in determining hydrogen uptake. These insights underscore the importance of not only reducing hydrogen costs but also designing supportive policies that address market acceptance and the full cost structure of green industrial products.

A comprehensive understanding of consumer preferences and demand factors is essential for successfully implementing demand-side strategies for alternative energy solutions such as hydrogen. This study aims to identify the key determinants influencing the adoption propensity for Hydrogen fuel cell vehicles (HFCVs) in the Kingdom of Saudi Arabia (KSA). Developing a conceptual framework to organise the key factors influencing consumers’ decisions to adopt or reject this technology. Using data from an online survey of 384 prospective customers we employed structural equation modelling (SEM) via Smart-PLS 4.1 to analyze consumer intent. The findings reveal that perceived benefits barriers opinions and governmental initiatives have a significant impact on the likelihood of HFCV adoption. The study emphasises the significance of collaborative efforts among key stakeholders including manufacturers hydrogen producers research institutions and financial entities in addressing challenges and advancing the development of the hydrogen transportation ecosystem in KSA. Financial incentives and subsidies such as purchasing subsidies awareness and reduced registration costs for HFCVs may be instituted.

With the growing significance of hydrogen in the global energy transition research on its pricing mechanisms has become increasingly crucial. Focusing on hydrogen markets predominantly supplied by electrolytic production this study proposes a nodal marginal hydrogen price decomposition algorithm that explicitly incorporates the time-delay dynamics inherent in hydrogen transmission. A four-dimensional price formation framework is established comprising the energy component network loss component congestion component and time-delay component. To address the nonconvex optimization challenges arising in the market-clearing model an improved second-order cone programming method is introduced. This method effectively reduces computational complexity through the reconstruction of time-coupled constraints and reformulation of the Weymouth equation. On this basis the analytical expression of the nodal marginal hydrogen price is rigorously derived elucidating how transmission dynamics influence each price component. Empirical studies using a modified Belgian 20-node system demonstrate that the proposed pricing mechanism dynamically adapts to load variations with hydrogen prices exhibiting a strong correlation with electricity cost fluctuations. The results validate the efficacy and superiority of the proposed approach in hydrogen energy market applications. This study provides a theoretical foundation for designing efficient and transparent pricing mechanisms in emerging hydrogen markets.

The operational optimization of industrial boilers utilizing hydrogen-enriched natural gas is constrained by two critical gaps: insufficient understanding of the coupled effects of hydrogen blending ratio equivalence ratio and boiler load on combustion performance— compounded by unresolved challenges of combustion instability flashback and elevated NOx emissions—and a lack of systematic investigations combining these parameters in industrial-scale systems (prior studies often focus on single variables like hydrogen fraction). To address this a comprehensive computational fluid dynamics (CFD) analysis was conducted on a 2.1 MW industrial boiler employing the Steady Laminar Flamelet Model (SLFM) with a modified k-ε turbulence model and the GRI-Mech 3.0 mechanism. Simulations covered hydrogen fractions (f(H2) = 0–25%) equivalence ratios (Φ = 0.8–1.2) and load conditions (15–100%). All NOx emissions reported herein are normalized to 3.5% O2 (mg/Nm3 ) for regulatory comparison. Results show that increasing the hydrogen content raises the flame temperature and NOx emissions while reducing CO and unburned hydrocarbons; a higher equivalence ratio elevates temperature and NOx with Φ = 0.8 balancing efficiency and emission control; and reducing load significantly lowers furnace temperature and NO emissions. Notably the boiler’s unique staged-combustion configuration (81% fuel supply to the central rich-combustion nozzle 19% to the concentric lean-combustion nozzle) was found to mitigate NOx formation by 15–20% compared to single-inlet burner designs and its integrated cyclone blades (generating maximum swirling velocity of 14.2 m/s at full load) enhanced fuel–air mixing which became particularly critical for maintaining combustion stability at low loads (≤20%) and high hydrogen blending ratios (≥20%). This study provides quantitative trade-off insights between combustion efficiency and pollutant formation offering actionable guidance for the safe efficient operation of hydrogen-enriched natural gas in industrial boilers.

This study investigates the combustion process in a marine spark-ignition engine fueled with an ammonia–hydrogen blend (15% hydrogen by volume) using a passive pre-chamber. A 3D-CFD model supported by a 1D engine model was employed to analyze equivalence ratios between 0.7 and 0.9 and pre-chamber nozzle diameters from 7 to 3 mm. Results indicate that combustion is consistently initiated by turbulent jets but at an equivalence ratio of 0.7 the charge combustion is incomplete. For lean mixtures reducing nozzle size improves flame propagation although not sufficiently to ensure stable operation. At an equivalence ratio of 0.8 reducing the nozzle diameter from 7 to 5 mm advances CA50 by about 6 CAD while further reduction causes minor variations. At richer conditions nozzle diameter plays a negligible role. Optimal performance was achieved with a 7 mm nozzle at equivalence ratio 0.8 delivering about 43% efficiency and 1.17 MW per cylinder.

The hydrogen energy industry is rapidly developing positioning hydrogen refueling stations (HRSs) as critical infrastructure for hydrogen fuel cell vehicles. Within these stations hydrogen compressors serve as the core equipment whose performance and reliability directly determine the overall system’s economy and safety. This article systematically reviews the working principles structural features and application status of mechanical hydrogen compressors with a focus on three prominent types based on reciprocating motion principles: the diaphragm compressor the hydraulically driven piston compressor and the ionic liquid compressor. The study provides a detailed analysis of performance bottlenecks material challenges thermal management issues and volumetric efficiency loss mechanisms for each compressor type. Furthermore it summarizes recent technical optimizations and innovations. Finally the paper identifies current research gaps particularly in reliability hydrogen embrittlement and intelligent control under high-temperature and high-pressure conditions. It also proposes future technology development pathways and standardization recommendations aiming to serve as a reference for further R&D and the industrialization of hydrogen compression technology.

The gradual exhaustion of fossil fuel reserves along with the adverse effects of their consumption on global climate drives the need for research into alternative energy sources that can meet the growing demand in a sustainable and eco-friendly way. Among these hydrogen stands out as one of the most promising options for the automotive sector being the cleanest available fuel and capable of being produced from renewable resources. This paper reviews the existing literature on compression ignition engines operating in a dualfuel configuration where diesel serves as the ignition source and hydrogen is used to enhance the combustion process. The reviewed studies focus on engine systems with hydrogen injection into the intake manifold. The investigations analyzed the influence of hydrogen energy fraction on combustion characteristics engine performance combustion stability and exhaust emissions in diesel/hydrogen dual-fuel engines operating under full or near-full-load conditions. The paper identifies the main challenges hindering the widespread and commercial application of hydrogen in diesel/hydrogen dual-fuel engines and discusses potential methods to overcome the existing barriers in this area.

Fuel cells are highly efficient electrochemical devices that convert the chemical energy of fuel directly into electrical energy while generating minimal pollutant emissions. In recent decades they have established themselves as a key technology for sustainable energy supply in the transport sector stationary systems and portable applications. In order to assess their real contribution to environmental protection and energy efficiency a comprehensive analysis of their life cycle Life Cycle Assessment (LCA) is necessary covering all stages from the extraction of raw materials and the production of components through operation and maintenance to decommissioning and recycling. Particular attention is paid to the environmental challenges associated with the extraction of platinum catalysts the production of membranes and waste management. Economic aspects such as capital costs the price of hydrogen and maintenance costs also have a significant impact on their widespread implementation. This manuscript presents detailed mathematical models that describe the electrochemical characteristics energy and mass balances degradation dynamics and cost structures over the life cycle of fuel cells. The models focus on proton exchange membrane fuel cells (PEMFCs) with possible extensions to other types. LCA is applied to quantify environmental impacts such as global warming potential (GWP) while the levelized cost of electricity (LCOE) is used to assess economic viability. Particular attention is paid to the sustainability challenges of platinum catalyst extraction membrane production and end-of-life material recovery. By integrating technical environmental and economic modeling the paper provides a systematic perspective for optimizing fuel cell deployment within a circular economy.

Integrated Energy Systems (IESs) which leverage the synergistic coordination of electricity heat and gas networks serve as crucial enablers for a low-carbon transition. Current research predominantly treats energy storage as a subordinate resource in dispatch schemes failing to simultaneously optimise IES economic efficiency and storage operators’ profit maximisation thereby overlooking their potential value as independent market entities. To address these limitations this study establishes an operator-autonomous management framework incorporating electrical thermal and hydrogen storage in IESs. We propose a joint optimal dispatch model for hybrid energy storage systems in low-carbon IES operation. The upper-level model minimises total system operation costs for IES operators while the lower-level model maximises net profits for independent storage operators managing various storage assets. These two levels are interconnected through power price and carbon signals. The effectiveness of the proposed model is verified by setting up multiple scenarios for example analysis.

The effect of tempering temperature and tempering time on the density of hydrogen traps hydrogen diffusivity and microhardness in a vanadium-modified AISI 4140 martensitic steel was determined. Tempering parameters were selected to activate the second third and fourth tempering stages. These conditions were intended to promote specific microstructural transformations. Permeability tests were performed using the electrochemical method developed by Devanathan and Stachurski and microhardness was measured before and after these tests. It was observed that hydrogen diffusivity is inversely proportional to microhardness while the density of hydrogen traps is directly proportional to microhardness. The lowest hydrogen diffusivity the highest trap density and the highest microhardness were obtained in the as-quenched condition and the tempering at 286 ◦C for 0.25 h. In contrast tempering at a temperature corresponding to the fourth tempering stage increases hydrogen diffusivity and decreases the density of hydrogen traps and microhardness. However as the tempering time or temperature increases the opposite occurs which is attributed to the formation of alloy carbides. Finally hydrogen has a softening effect for tempering temperatures corresponding to the fourth tempering stage tempering times of 0.25 h and in the as-quenched condition. However with increasing tempering time hydrogen has a hardening effect.