Italy

Europe’s heavy reliance on diesel power for nearly half of its railway lines for both goods and passengers has significant implications for carbon emissions. To address this challenge the European Union advocates for a shift towards hydrogen-based mobility necessitating the development of robust and cost-effective hydrogen supply chains at regional and national levels. Leveraging renewable energy sources such as wind farms and solid biomass could foster the transition to sustainable hydrogen-based transportation. In this study a mixed-integer linear programming approach integrated with an external heavy-duty refueling station analysis model is employed to address the optimal design of a new hydrogen supply chain. Through multi-objective optimization this study aimed to minimize the overall daily costs and emissions of the supply chain. By applying the model to a case study in Sicily different scenarios with varying supply chain configurations and wind curtailment factors were explored. The findings revealed that increasing the wind curtailment factor from 1% to 2% led to reductions of 12% and 15% in the total daily emission costs and network costs respectively. Additionally centralized biomass-based plants dominated hydrogen production accounting for 96% and 94% of the total production under 1% and 2% wind curtailment factors respectively. Furthermore transporting gaseous hydrogen via tube trailers proved more cost effective than using tanker trucks for liquid hydrogen when compressed gaseous hydrogen is required at the dispenser of forecourt refueling stations. Finally the breakdown of the levelized cost for the hydrogen refuelling station strongly depends on the form of hydrogen received at the gate namely liquid or gaseous. Specifically for the former the dispenser accounts for 60% of the total cost whereas for the latter the compressor is responsible for 58% of the total cost. This study highlights the importance of preliminary and quantitative analyses of new hydrogen supply chains through model-based optimization.

Liquid organic hydrogen carriers (LOHCs) are considered a promising hydrogen storage technology. Heat must be exchanged with an external medium such as a heat transfer fluid for the required chemical reactions to occur. Batch reactors are simple but useful solutions for small-scale storage applications which can be modelled with a lumped parameter approach adequately reproducing their dynamic performance. For such reactors power is consumed to circulate the external heat transfer fluid and stir the organic liquid inside the reactor and heat transfer performance and power consumption are two key parameters in reactor optimisation. Therefore with reference to the hydrogen release phase this paper describes a procedure to optimise the reactor thermal design based on a lumped-parameter model in terms of heat transfer performance and minimum power consumption. Two batch reactors are analysed: a conventional jacketed reactor with agitation nozzles and a half-pipe coil reactor. Heat transfer performance is evaluated by introducing a newly defined dimensionless parameter the Heat Transfer Ratio (HTR) whose value directly correlates to the heat rate required by the carrier's dehydrogenation reaction. The resulting model is a valid tool for adequately reproducing the hydrogen storage behaviour within dynamic models of complex and detailed energy systems.

High fluctuations in the combustion process from one cycle to another referred to as cycle-by-cycle variations can have adverse effects on internal combustion engine performances particularly in spark ignition (SI) engines. These effects encompass incomplete combustion the potential for misfires and adverse impacts on fuel economy. Furthermore the cycle-by-cycle variations can also affect a vehicle’s drivability and overall comfort especially when operating under lean-burn conditions. Although many cycle-by-cycle analyses have been investigated extensively in the past there is limited in-depth knowledge available regarding the causes of cycle-by-cycle (CbC) variations in hydrogen lean-burn SI engines. Trying to contribute to this topic the current study presents a comprehensive analysis of the CbC variations based on the cylinder pressure data. The study was carried out employing a hydrogen single-cylinder research SI engine. The experiments were performed by varying more than fifty operating conditions including the variations in lambda spark advance boost pressure and exhaust gas recirculation however the load and speed were kept constant throughout the experimental campaign. The results indicate that pressure exhibits significant variations during the combustion process and minor variations during non-combustion processes. In the period from the inlet valve close till the start of combustion pressure exhibits the least variations. The coefficient of variation of pressure (COVP) curve depicts three important points in H2-ICE as well: global minima global maxima and second local minima. The magnitude of the COVP curve changes across all the operating conditions however the shape of the COVP curve remains unchanged across all the operating conditions indicating its independence from the operating condition in an H2-ICE. This study presents an alternative approach for a quick combustion analysis of hydrogen engines. Without the need for more complex methodologies like heat release rate analysis the presented cylinder pressure cycle-by-cycle analysis enables a quick and precise identification of primary combustion features (start of combustion center of combustion end of combustion and operation condition stability). Additionally the engine control unit could implement these procedures to automatically adjust cycle-by-cycle variations therefore increasing engine efficiency.

Climate change has prompted the international community to invest heavily in renewable energy sources in order to gradually replace fossil fuels. Whilst energy systems will be increasingly based on non-programmable renewable sources hydrogen is the main player when it comes to the role of energy reserve. This change has triggered a fast development of hydrogen production technologies with increasing use and installation of hydrogen generators (electrolyzers) in both the civil and industrial sector. The implementation of such investments requires the need for accurate design and verification of hydrogen systems with particular attention on fire safety. Due to its chemical-physical characteristics hydrogen is highly flammable and is often stored at very high-pressure levels. ISO 22734 and NFPA 2 are the main international standards which are currently available for the design of hydrogen generators and systems both of which include fire safety requirements. This paper analyses the main existing Regulations Codes and Standards (RCS) for hydrogen generators with the purpose of evaluating and comparing fire safety measures with focus on both active protection (detection systems extinguishing systems) and passive protection (safety distances separation walls). The scope of the paper is to identify safety measures which can be considered generally applicable and provide a reference for further fire safety regulations. The analysis carried out identifies potential gaps in RCS and suggests areas for potential future research.

The capabilities of an OpenFOAM solver to reproduce the transition of stoichiometric H2-air mixtures to detonation in obstructed 2-D channels were tested. The process is challenging numerically as it involves the ignition of a flame kernel its subsequent propagation and acceleration interaction with obstacles formation of shock waves ahead and detonation onset (DO). Two different obstacle configurations were considered in 10-mm high × 1-m long channels: (i) wavy walls (WW) that mimic the behavior of fencetype obstacles but prevent abrupt area changes. In this case flame acceleration (FA) is strongly affected by shock-flame interactions and DO often results from the compression of the gas present between the accelerating flame front and a converging section of the channel. (ii) Fence-type (FT) obstacles. In this case FA is driven by the increase in flame surface area as a result of the interaction of the flame front with the unburned gas flow field ahead particularly downstream of obstacles; shock-flame interactions play a role at the later stages of FA and DO takes place upon reflection of precursor shocks from obstacles. The effect of initial pressure p0 = 25 50 and 100 kPa at constant blockage ratio (BR = 0.6) was investigated and compared for both configurations. Results show that for the same initial pressure (p0 = 50 kPa) the obstacle configurations could lead to different final propagation regimes: a quasi-detonation for WW and a choked-flame for FT due to the increased losses for the latter. At p0 = 25 kPa however while both configurations result in choked flames WW seem to exhibit larger velocity deficits than FT due to longer flame-precursor shock distances during quasi-steady propagation and to the increased presence of unburnt mixture downstream of the tip of the flame that homogeneously explodes providing additional support to the propagation of the flame.

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.

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.

The central role of hydrogen in the EU’s decarbonization strategy has increased the importance of critical raw materials. To address this the EU has taken legislative steps including the 2023 Critical Raw Materials Act (CRMA) to ensure a stable supply. Using a leader–follower Stackelberg game framework this study analyzes CRM market dynamics integrating CRMA compliance through rules on sourcing and stockpiling value chain resilience via the inclusion of supply diversification strategies and geopolitical influences by modeling exporter behaviors and trade dependencies. Results highlight the potential for strategic behavior by major exporters stressing the benefits of diversifying export sources and maintaining strategic stockpiles to stabilize supply. The findings provide insights into the EU’s efforts to secure CRM supplies key to achieving decarbonization goals and fostering a sustainable energy transition. Future research should explore alternative cost-reduction strategies mitigate exporter market power and evaluate the implications for pricing mechanisms market outcomes and consumer welfare

Methane is a significant contributor to anthropogenic greenhouse gas emissions. Blending hydrogen with natural gas in existing networks presents a promising strategy to reduce these emissions and support the transition to a carbon-neutral energy system. However hydrogen’s potential for atmospheric release raises safety and environmental concerns necessitating an assessment of its impact on methane emissions and leakage behavior. This study introduces a methodology for estimating how fugitive emissions change when a natural gas network is shifted to a 10% hydrogen blend by combining analytical flowrate models with data from sampled leaks across a natural gas network. The methodology involves developing conversion factors based on existing methane emission rates to predict corresponding hydrogen emissions across different sections of the network including mainlines service lines and facilities. Our findings reveal that while the overall volumetric emission rates increase by 5.67% on the mainlines and 3.04% on the service lines primarily due to hydrogen’s lower density methane emissions decrease by 5.95% on the mainlines and 8.28% on the service lines. However when considering the impact of a 10% hydrogen blend on the Global Warming Potential the net reduction in greenhouse gas emissions is 5.37% for the mainlines and 7.72% for the service lines. This work bridges the gap between research on hydrogen leakage and network readiness which traditionally focuses on safety and environmental sustainability studies on methane emission.

In order to achieve the ambitious goal of “carbon neutrality” countries around the world are striving to develop clean energy. Against this background this paper takes China and Italy as representatives of developing and developed countries to summarize the energy structure composition and development overview of the two countries. The paper analyzes the serious challenges facing the future energy development of both countries and investigates the possibilities of energy cooperation between the two countries taking into account their respective advantages in energy development. By comparing the policies issued by the two governments to encourage clean energy development this paper analyzes the severe challenges faced by the two countries’ energy development in the future and combines their respective energy development advantages to look forward to the possibility of energy cooperation between the two countries in the future. This lays the foundation for China and Italy to build an “Energy Road” after the “Silk Road”.