Publications

To ensure the safe and reliable operation of hydrogen-blended natural gas (HBNG) pipelines in urban utility tunnels this study conducted a comprehensive CFD simulation of the leakage and diffusion characteristics of HBNG in confined underground environments. Utilizing ANSYS CFD software (2024R1) a three-dimensional physical model of a utility tunnel was developed to investigate the influence of key parameters such as leak sizes (4 mm 6 mm and 8 mm)—selected based on common small-orifice defects in utility tunnel pipelines (e.g. corrosion-induced pinholes and minor mechanical damage) and hydrogen blending ratios (HBR) ranging from 0% to 20%—a range aligned with current global HBNG demonstration projects (e.g. China’s “Medium-Term and Long-Term Plan for Hydrogen Energy Industry Development”) and ISO standards prioritizing 20% as a technically feasible upper limit for existing infrastructure on HBNG diffusion behavior. The study also evaluated the adequacy of current accident ventilation standards. The findings show that as leak orifice size increases the diffusion range of HBNG expands significantly with a 31.5% increase in diffusion distance and an 18.5% reduction in alarm time as the orifice diameter grows from 4 mm to 8 mm. Furthermore hydrogen blending accelerates gas diffusion with each 5% increase in HBR shortening the alarm time by approximately 1.6 s and increasing equilibrium concentrations by 0.4% vol. The current ventilation standard (12 h−1 ) was found to be insufficient to suppress concentrations below the 1% safety threshold when the HBR exceeds 5% or the orifice diameter exceeds 4 mm—thresholds derived from simulations showing that under 12 h−1 ventilation equilibrium concentrations exceed the 1% safety threshold under these conditions. To address these gaps this study proposes an adaptive ventilation strategy that uses variable-frequency drives to adjust ventilation rates in real time based on sensor feedback of gas concentrations ensuring alignment with leakage conditions thereby ensuring enhanced safety. These results provide crucial theoretical insights for the safe design of HBNG pipelines and ventilation optimization in utility tunnels.

As the need for sustainable hydrogen storage solutions increases enhancing the bonding interface between polymer liners and carbon fiber-reinforced polymer (CFRP) in Type IV hydrogen tanks is essential to ensure tank integrity and safety. This study investigates the effect of plasma treatment on polyethylene (PE) and PE/graphene nanoplatelets (GNP) composites to optimize bonding with CFRP simulating the liner-CFRP interface in hydrogen tanks. Initially plasma treatment effects on PE surfaces were assessed focusing on plasma energy and exposure time with key surface modifications characterized and bonding performance being evaluated. Plasma treatment on PE/GNP composites with increasing GNP content was then examined comparing the bonding effectiveness of untreated and plasma-treated samples. Wedge peel tests revealed that plasma treatment significantly enhanced PE-CFRP bonding with optimal conditions at 510 W and 180 s resulting in 212 % and 165 % increases in the wedge peel strength and fracture energy respectively. Plasma-treated PE/GNP composites with 0.75 wt.% GNP achieved a notable bonding enhancement with CFRP showing 528 % and 269 % improvements in strength and fracture energy over untreated neat PE-CFRP samples. These findings offer practical implications for improving the mechanical performance of hydrogen storage tanks contributing to safer and more efficient hydrogen storage systems for a sustainable energy future.

Pressure collapse in sloshing cryogenic liquid hydrogen tanks is a challenge for existing models which often diverge from experimental data. This paper presents a novel lumped-parameter model that overcomes these limitations. Based on a control volume analysis our approach simplifies the complex non-equilibrium physics into a single dimensionless ordinary differential equation governing the liquid’s temperature. We demonstrate this evolution is controlled by one key parameter: the interfacial Nusselt number (). A method for estimating directly from pressure data is also provided. Validated against literature data the model predicts final tank temperatures with deviation of 0.88K (<5% relative error) from measurements thereby explaining the associated pressure collapse. Furthermore our analysis reveals that the Nusselt number varies significantly during a single sloshing event—with calculated values ranging from a peak of 5.81 × 105 down to 7.58 × 103—reflecting the transient nature of the phenomenon.

This review investigates hydrogen production via photocatalysis using ammonia a carbon-free source potentially present in wastewater. Photocatalysis offers low energy requirements and high conversion efficiency compared to electrocatalysis thermocatalysis and plasma catalysis. However challenges such as complex material synthesis low stability spectral inefficiency high costs and integration barriers hinder industrial scalability. The review addresses thermodynamic requirements reaction mechanisms and the role of pH in optimizing photocatalysis. By leveraging ammonia’s potential and advancing photocatalyst development this study provides a framework for scalable sustainable hydrogen production and simultaneous ammonia decomposition paving the way for innovative energy solutions and wastewater management.

Zero-export photovoltaic systems are an option to transition to Smart Grids. They decarbonize the sector without affecting third parties. This paper proposes the analysis of a zero-export PVS with a green hydrogen generation and storage system. This configuration is feasible to apply by any selfgeneration entity; it allows the user to increase their resilience and independence from the electrical network. The technical issue is simplified because the grid supplies no power. The main challenge is finding an economic balance between the savings in electricity billing proportional to the local electricity rate and the complete system’s investment operation and maintenance expenses. This manuscript presents the effects of the power sizing on the efficacy of economic savings in billing (ηSaving ) and the effects of the cost reduction on the levelized cost of energy (LCOE) and a discounted payback period (DPP) based on net present value. In addition this study established an analytical relationship between LCOE and DPP. The designed methodology pro poses to size and selects systems to use and store green hydrogen from the zero-export photo voltaic system. The input data in the case study are obtained experimentally from the Autonomous University of the State of Quintana Roo located on Mexico’s southern border. The maximum power of the load is LPmax = 500 kW and the average power is LPmean = 250 kW; the tariff of the electricity network operator has hourly conditions for a medium voltage demand. A suggested semi-empirical equation allows for determining the efficiency of the fuel cell and electrolyzer as a function of the local operating conditions and the nominal power of the com ponents. The analytical strategy the energy balance equations and the identity functions that delimit the operating conditions are detailed to be generalized to other case studies. The results are obtained by a computer code programmed in C++ language. According to our boundary conditions results show no significant savings generated by the installation of the hydrogen system when the zero-export photovoltaic system Power ≤ LPmax and DPP ≤ 20 years is possible only with LCOE ≤ 0.1 $/kWh. Specifically for the Mexico University case study zero-export photovoltaic system cost must be less than 310 $/kW fuel cell cost less than 395 $/kW and electrolyzer cost less than 460 $/kW.

This study offers a novel techno-economic evaluation of a small hydrogen generation system included into a residential villa in Sharjah. The system is designed to utilize solar energy for hydrogen production using an electrolyzer. The study assesses two scenarios: one lacking a fuel cell and the other incorporating a fuel cell stack for backup power. The initial scenario employs a solar-powered electrolyzer for hydrogen production attaining a competitive levelized cost of energy (LCOE) of $0.1846 per kWh and a hydrogen cost of $4.65 per kg. These data underscore the economic viability of utilizing electrolyzers for hydrogen generation. The system produces around 1230 kg of hydrogen per annum rendering it appropriate for many uses. Nevertheless the original investment expenditure of $73980 necessitates more optimization. The second scenario includes a 10 kW fuel cell for energy autonomy. This scenario has a marginally reduced LCOE of 0.1811 $/kWh and a cumulative net present cost of $72600. The fuel cell runs largely at night proving the efficiency of the downsizing option in decreasing capital expense. The system generates electricity from solar panels (66.1 MWh/year) and the fuel cell (16.9 MWh/year) exhibiting a multi-source power generating technique. The results indicate that scaled-down hydrogen generation systems both with and without fuel cells may offer sustainable and possibly lucrative renewable energy options for household use especially in areas with ample solar resources such as Sharjah.

The transition towards a low-carbon energy system remains a critical challenge for regions heavily dependent on fossil fuels such as Andalusia. This study proposes an energy planning framework based on the Low Emissions Analysis Platform (LEAP) to model alternative scenarios and assess the feasibility of meeting the 2030 and 2050 decarbonisation targets. Three scenarios are evaluated the Tendential Scenario (TS01) the Efficient Scenario (ES01) and the Efficient UJA (EEUJA) Scenario with this last being specifically designed to ensure full compliance with regional energy goals. The results indicate that while the Tendential Scenario falls short in reducing primary energy consumption and greenhouse gas (GHG) emissions the Efficient Scenario achieves significant progress though it is still insufficient to meet renewable energy integration targets. The proposed EEUJA Scenario introduces more ambitious measures including large-scale electrification smart grids energy storage and green hydrogen deployment resulting in a 39.5% reduction in primary energy demand by 2030 and 97% renewable energy penetration by 2050. Furthermore by implementing sector-specific decarbonisation strategies for the industry transport residential and services sectors Andalusia could position itself as a frontrunner in the energy transition while minimising economic and environmental risks. These findings underscore the importance of policy enforcement technological innovation and financial incentives in securing a sustainable energy future. The methodology developed in this study is replicable for other regions aiming for carbon neutrality and energy resilience through strategic planning and scenario analysis.

This study explores the feasibility parameters of a potential investment plan for injecting “green” hydrogen into the existing natural gas supply network in Greece. To this end a preliminary profitability optimization analysis was conducted through key performance indicators such as the cost of hydrogen and the socio-environmental benefit of carbon savings followed by break-even and sensitivity analyses. The identification of the major impact drivers of the assessment was based on the examination of a set of operational scenarios of varying hydrogen and natural gas flow rates. The results show that high natural gas capacities with a 5% hydrogen content by volume are the optimal case in terms of socio-economic viability but the overall profitability is too sensitive to hydrogen pricing rendering it unfeasible without additional motives measures and pricing strategies. The results feed into the main challenge of implementing commercial “green” hydrogen infrastructures in the market in a sustainable and feasible manner.

The transition to sustainable energy is crucial for mitigating climate change impacts. This study addresses this imperative by simulating a green hydrogen supply chain tailored for residential cooking in Oman. The supply chain encompasses solar energy production underground storage pipeline transportation and residential application aiming to curtail greenhouse gas emissions and reduce the levelized cost of hydrogen (LCOH). The simulation results suggest leveraging a robust 7 GW solar plant. Oman achieves an impressive annual production of 9.78 TWh of green hydrogen equivalent to 147808 tonnes of H2 perfectly aligning with the ambitious goals of Oman Vision 2040. The overall LCOH for the green hydrogen supply chain is estimated at a highly competitive 6.826 USD/kg demonstrating cost competitiveness when benchmarked against analogous studies. A sensitivity analysis highlights Oman’s potential for cost-efective investments in green hydrogen infrastructure propelling the nation towards a sustainable energy future. This study not only addresses the pressing issue of reducing carbon emissions in the residential sector but also serves as a model for other regions pursuing sustainable energy transitions. The developed simulation models are publicly accessible at https://hychain.co.uk providing a valuable resource for further research and development in the feld of green hydrogen supply chains.

The increasing demand for carbon-free energy in recent years has positioned hydrogen as a viable option. However its current production remains largely dependent on carbon-emitting sources. In this context natural hydrogen generated through geological processes in the Earth’s subsurface has emerged as a promising alternative. The present study provides the first national-scale assessment of natural dihydrogen (H2) potential in Uruguay by developing a catalog of potential H2-generating rocks identifying prospective exploration areas and proposing H2 systems there. The analysis includes a review of geological and geophysical data from basement rocks and onshore sedimentary basins. Uruguay stands out as a promising region for natural H2 exploration due to the significant presence of potential H2-generating rocks in its basement such as large iron formations (BIFs) radioactive rocks and basic and ultrabasic rocks. Additionally the Norte Basin exhibits potential efficient cap rocks including basalts and dolerites with geological analogies to the Mali field. Indirect evidence of H2 in a free gas phase has been observed in the western Norte Basin. This suggests the presence of a potential H2 system in this area linked to the Arapey Formation basalts (seal) and Mesozoic sandstones (reservoir). Furthermore the proposed H2 system could expand exploration opportunities in northeastern Argentina and southern Brazil given the potential presence of similar play/tramp.