Publications

The adoption of liquid hydrogen (LH2) as an energy carrier presents significant opportunities for distributing large quantities of hydrogen efficiently. However ensuring safety of LH2 transfer operations requires the evo lution of suitable technologies and regulatory framework. This study offers an extensive overview of technical considerations and safety aspects pertaining to liquid hydrogen installations and mobile applications. A signif icant lack of regulations specifically tailored for LH2 transfer operations is highlighted. Additionally experi mental findings and outcomes of the modelling activities carried out in previous research are presented shedding light on the combustion and ignition behaviour of liquid hydrogen during accident scenarios. The identification of research gaps and ongoing research projects underscores the importance of continued investigation and development of this critical area.

The advancement of sustainable solutions through renewable energy sources is crucial to mitigate carbon emissions. This study reports a novel system for an airport utilizing geothermal biomass and PV solar energy sources. The proposed system is capable of producing five useful outputs including electrical power hot water hydrogen kerosene and space heating. In open literature there has been no system reported with these combination of energy sources and outputs. The system is considered for Vancouver Airport using the most recent statistics available. The geothermal sub-system introduced is also unique which utilizes carbon dioxide captured as the heat transfer medium for power generation and heating. The present system is considered using thermodynamic analysis through energetic and exergetic approaches to determine the variation in system performance based on different annual climate conditions. Biomass gasification and kerosene production are evaluated based on the Aspen Plus models. The efficiencies of the geothermal system with the carbon dioxide reservoir are found to have energetic and energetic efficiencies of 78 % and 37 % respectively. The total hydrogen production projection is obtained to be 452 tons on an annual basis. The kerosene production mass flow rate is reported as 0.112 kg/s. The overall energetic and exergetic efficiencies of the system are found to be 41.8 % and 32.9 % respectively. This study offers crucial information for the aviation sector to adopt sustainable solutions more effectively.

One such technology is hydrogen-based which utilizes hydrogen to generate energy without emission of greenhouse gases. The advantage of such technology is the fact that the only by-product is water. Efficient storage is crucial for the practical application of hydrogen. There are several techniques to store hydrogen each with certain advantages and disadvantages. In gaseous hydrogen storage hydrogen gas is compressed and stored at high pressures requiring robust and expensive pressure vessels. In liquid hydrogen storage hydrogen is cooled to extremely low temperatures and stored as a liquid which is energy-intensive. Researchers are exploring advanced materials for hydrogen storage including metal hydrides carbonbased materials metal–organic frameworks (MOFs) and nanomaterials. These materials aim to enhance storage capacity kinetics and safety. The hydrogen economy envisions hydrogen as a clean energy carrier utilized in various sectors like transportation industry and power generation. It can contribute to decarbonizing sectors that are challenging to electrify directly. Hydrogen can play a role in a circular economy by facilitating energy storage supporting intermittent renewable sources and enabling the production of synthetic fuels and chemicals. The circular economy concept promotes the recycling and reuse of materials aligning with sustainable development goals. Hydrogen availability depends on the method of production. While it is abundant in nature obtaining it in a clean and sustainable manner is crucial. The efficiency of hydrogen production and utilization varies among methods with electrolysis being a cleaner but less efficient process compared to other conventional methods. Chemisorption and physisorption methods aim to enhance storage capacity and control the release of hydrogen. There are various viable options that are being explored to solve these challenges with one option being the use of a multilayer film of advanced metals. This work provides an overview of hydrogen economy as a green and sustainable energy system for the foreseeable future hydrogen production methods hydrogen storage systems and mechanisms including their advantages and disadvantages and the promising storage system for the future. In summary hydrogen holds great promise as a clean energy carrier and ongoing research and technological advancements are addressing challenges related to production storage and utilization bringing us closer to a sustainable hydrogen economy.

The spread of renewable energy (RE) generation not only promotes economy and the environmental protection but also brings uncertainty to power system. As the integration of hydrogen and electricity can effectively mitigate the fluctuation of RE generation an electricity-hydrogen integrated energy system is constructed. Then this paper studies the source-load uncertainties and corresponding correlation as well as the electricity-hydrogen price uncertainties and corresponding correlation. Finally an optimal scheduling model considering economy environmental protection and demand response (DR) is proposed. The simulation results indicate that the introduction of the DR strategy and the correlation of electricity-hydrogen price can effectively improve the economy of the system. After introducing the DR the operating cost of the system is reduced by 5.59% 10.5% 21.06% in each season respectively. When considering the correlation of EP and HP the operating cost of the system is reduced by 4.71% 6.47% 1.4% in each season respectively.

This study investigates the use of hydrogen (H2 ) as a substitute for compressed natural gas (CNG) in a heavyduty (HD) six-cylinder engine focusing on both port fuel injection (PFI) and direct injection (DI) systems. Numerical modeling in a 0D/1D environment was employed simulating engine operation under stationary conditions and during the worldwide harmonized transient cycle (WHTC) and worldwide harmonized vehicle cycle (WHVC) homologation cycles. Results indicated a reduction in torque (7% for direct injection and 21.5% for port fuel injection) and power (32% for direct injection and 35.5% for port fuel injection) when switching from CNG to H2 . Efficiency slightly decreased primarily due to knocking at high engine loads and speeds during H2 operation. The reduced torque and power were mainly attributed to the turbocharger being undersized for H2 given its low density and the lean mixture combustion strategy used. Upgrading the turbocharger or implementing a two-stage compressor could restore or even improve torque and power levels compared to CNG. Heat transfer losses in the H2 engine were lower than with CNG due to the lower incylinder temperature resulting from the lean mixture strategy which also contributed to a significant reduction in nitrogen oxides (NOx ) emissions approximately 2.5 times lower than those with CNG. Despite a notable exhaust energy loss during H2 operation caused by delayed combustion due to knocking the lower NOx emissions and absence of carbon emissions are crucial for reducing pollution. During vehicle cycles selecting an optimal gear-shift strategy is critical to mitigating the performance gap resulting from reduced torque and power with H2 fueling.

This work develops a novel optimisation approach to determine the optimal installed capacities of wind solar and hydrogen storage systems for the continuous production of green hydrogen targeting the lowest "True Cost of Hydrogen" (TCOH). TCOH is a metric that combines both costs and life cycle environmental impacts facilitating decision-making and supporting project design. Two hypothetical scenarios were evaluated using evolutionary optimisation of the TCOH namely the “Slow” or “Fast” technology developments projected for 2030. Results show that optimising TCOH (for both cost and environmental impacts) may reduce a large range of environmental impact categories by up to 37% while increasing cost by up to 0.23€/kg H2. Overall the proposed method allows for a cost-effective hydrogen production but also contributes to the mitigation of relevant environmental impacts. Our approach has the potential to add to the current carbon footprint requirements towards truly sustainable pathways for green hydrogen production.

Underground hydrogen (H2) storage (UHS) and carbon dioxide (CO2) geo-storage (CGS) are prominent methods of meeting global energy needs and enabling a low-carbon global economy. The pore-scale distribution reservoir-scale storage capacity and containment security of H2 and CO2 are significantly influenced by interfacial properties including the equilibrium contact angle (θE) and solid-liquid and solid-gas interfacial tensions (γSL and γSG). However due to the technical constraints of experimentally determining these parameters they are often calculated based on advancing and receding contact angle values. There is a scarcity of θE γSL and γSG data particularly related to the hydrogen structural sealing potential of caprock which is unavailable in the literature. Young's equation and Neumann's equation of state were combined in this study to theoretically compute these three parameters (θE γSL and γSG) at reservoir conditions for the H2 and CO2 geo-storage potential. Pure mica organic-aged mica and alumina nano-aged mica substrates were investigated to explore the conditions for rock wetting phenomena and the sealing potential of caprock. The results reveal that θE increases while γSG decreases with increasing pressure organic acid concentration and alkyl chain length. However γSG decreases with increasing temperatures for H2 gas and vice versa for CO2. In addition θE and γSL decrease whereas γSG increases with increasing alumina nanofluid concentration from 0.05 to 0.25 wt%. Conversely θE and γSL increase whereas γSG decreases with increasing alumina nanofluid concentration from 0.25 to 0.75 wt%. The hydrogen wettability of mica (a proxy of caprock) was generally less than the CO2 wettability of mica at similar physio-thermal conditions. The interfacial data reported in this study are crucial for predicting caprock wettability alterations and the resulting structural sealing capacity for UHS and CGS.

The study investigates the potential of transitioning Iraq a nation significantly dependent on fossil fuels toward a green hydrogen-based energy system as a pathway to achieving sustainable economic resilience. As of 2022 Iraqi energy supply is over 90% reliant on hydrocarbons which also account for 95% of the country foreign exchange earnings. The global energy landscape is rapidly shifting towards cleaner alternatives and the volatility of oil prices has made it imperative for the country to diversify its energy sources. Green hydrogen produced through water electrolysis powered by renewable energy sources such as solar and wind offers a promising alternative given country vast renewable energy potential. The analysis indicates that with strategic investments in green hydrogen infrastructure the country could reduce its hydrocarbon dependency by 30% by the year 2030. This transition could not only address pressing environmental challenges but also contribute to the economic stability of the country. However the shift to green hydrogen is not without significant challenges including water scarcity technological limitations and the necessity for a robust regulatory framework. The findings underscore the importance of international partnerships and supportive policies in facilitating this energy transition. Adopting renewable energy and green hydrogen technologies the country has the potential to become a leader in sustainable energy within the region. This shift would not only drive economic growth and energy security but also contribute to global efforts towards environmental sustainability positioning country favorably in a future low-carbon economy.

In the automotive sector hydrogen is being increasingly explored as an alternative fuel to replace conventional carbon-based fuels. Its combustion characteristics make it well-suited for adaptation to internal combustion engines. The wide flammability range of hydrogen allows for higher dilution conditions resulting in enhanced combustion efficiency. When combined with lean combustion strategies hydrogen significantly reduces environmental impact virtually eliminating carbon dioxide and nitrogen oxide emissions while maintaining high thermal efficiency. This paper aims to assess the potential of using an outwardly opening poppet valve hydrogen direct injection (DI) system in a small engine for light-duty applications. To achieve this a comparison of performance emission levels and combustion parameters is conducted on a single-cylinder spark-ignition (SI) research engine fueled by hydrogen using both port fuel injection (PFI) and this new direct injection system. Two different engine loads are measured at multiple air dilution and injection timing conditions. The results demonstrate notable efficiency improvements ranging from 0.6% to 1.1% when transitioning from PFI to DI. Accurate control of injection timing is essential for achieving optimal performance and low emissions. Delaying the start of injection results in a 7.6% reduction in compression work at low load and a 3.9% reduction at high load. This results in a 3.1-3.2% improvement in ISFC in both load conditions considered.

The use of highly efficient cogeneration systems fueled by pure hydrogen such as Solid Oxide Fuel Cells (SOFCs) in the residential sector is one of the new frontiers for achieving the net zero greenhouse gas emissions tran sitions. The lack of experimental studies in this area prompted the authors to propose the present paper. It refers to hydrogen-fueled SOFC 1 kW-sized integrated into the plant system of a single-family villa configurated as a nearly Zero Energy Building. The multiple objectives are: show the technical feasibility of this technology in building; analyse the data of a continuous monitoring campaign in wintertime; highlight the real performance compared to the manufacturer’s declaration. The results demonstrate that in particular conditions of photo voltaic production it is possible to meet the home electric loads and have a surplus of energy to store or send to the national power grid. The calculated electrical efficiency is equal to 0.47 ÷ 0.48 while the maximum overall efficiency is 0.93.