Institution of Gas Engineers & Managers

A gas turbine is usually installed inside an acoustic enclosure where the fuel gas supply system is also placed. It is common practice using CFD analysis to simulate the accidental fuel gas release inside the enclosure and the consequent dispersion. These numerical studies are used to properly design the gas detection system according to specific safety criteria which are well defined when the fuel gas is a conventional natural gas. Package design is done to prevent that any sparking items and hot surfaces higher than auto-ignition temperature could be a source of ignition in case of leak. Nevertheless it is not possible to exclude that a leakage from a theoretical point of view could be ignited and for this reason a robust design requires that the enclosure structure is able to withstand the overpressure generated by a gas cloud ignition. Moving to hydrogen as fuel gas makes this design constraint much more relevant for its known characteristics of reactiveness large range of flammability maximum burning velocity etc. In such context gas leak and dispersion analysis become even more crucial because a correct prediction of these scenarios can guide the design to a safe configuration. The present work shows a comparison of the dispersion of different leakages inside a gas turbine enclosure carried out with two different CFD tools Ansys CFX and FLACS. This verification is considered essential since dispersion analysis results are used as initial conditions for gas cloud ignition simulations strictly necessary to predict the consequence in term of overpressure without doing experimental tests.

Polymeric materials are widely used in hydrogen energy system such as FCEV and hydrogen refueling stations under high-pressure condition. The permeation property (coefficients of permeation diffusion and solubility) of polymers under high-pressure hydrogen condition should be discussed as parameters to develop those devices. Also the property should be determined to understand influence of the compression by the pressure on polymer materials. A device which can measure gas permeation property of polymer materials accurately in equilibrium state under high-pressure environment is developed and the reliability of the measurements is ensured. High-pressure hydrogen gas permeability characteristics up to 100 MPa are measured for high-density polyethylene. An advantage of the method is discussed comparing with the non-equilibrium state method focusing on the hydrostatic pressure effect. Deterioration of hydrogen permeability is observed along with the decrease of diffusion coefficient which is supposedly affected by hydrostatic compression effect with the increase of environment pressure.

Hydrogen can manage intermittent Renewable Energy Sources (RES) especially in high-RES share systems. The energy transition calls for mature low cost low space solutions bringing the attention to unitized items such as the reversible Solid Oxide Cell (rSOC). This device made of a single unit can work as an electrolyzer and as fuel cell with high efficiency fuel flexibility and producing combined heat. The objective of this review is to identify and classify rSOC applications to the building sector as an effective solution and to show how much this technology is near to its commercialisation. Research & Development projects were analysed and discussed for a comprehensive overview. Conclusions show an increasing interest in the reversible technology although it is still at pre industrialisation stage with few real applications in the building sector of which the majority is reported commented and compared in this paper for the first time.

Hydrogen is emerging as a critical component in the global energy transition providing a low-carbon alternative for sectors such as industry and transportation. This paper aims to comprehensively address water usage in hydrogen production by exploring the water demands of different production methods and their implications for water management particularly in Texas. Key variables influencing water consumption are identified and potential water demands under different hydrogen market scenarios are estimated. Using spatial analysis regions where hydrogen production may stress local water resources are identified alongside policy recommendations for sustainable water use.

This report explores how hydrogen could be taken up in the UK and how this in turn translates to each sector from both global and UK perspectives to understand the practical implications of global and UK targets and projections on hydrogen innovation opportunities:

♦ Assessing demand for hydrogen sets out the context and the approach taken in the assessment of global and UK sector hydrogen needs including the development of specific UK scenarios for hydrogen deployment and innovation across the energy system and supply chain.

♦ Key insights discusses the insights and an overview of the outputs from the implementation of the UK deployment scenarios in whole energy system modelling.

♦ Hydrogen production storage and distribution and demand explore these areas in more detail setting out the current state and potential trajectories for hydrogen in each sector both globally and in the UK up to 2050.

This report can also be downloaded free on the Hydrogen Innovation Initative website.

A viable green energy source for heavy industries and transportation is hydrogen. The internal combustion engine (ICE) when powered by hydrogen offers an economical and adaptable way to quickly decarbonize the transportation industry. In general two techniques are used to inject hydrogen into the ICE combustion chamber: port injection and direct injection. The present work examined direct injection technology highlighting the need to understand and manage hydrogen mixing within an ICE’s combustion chamber. Before combusting hydrogen it is critical to study its propagation and mixture behavior just immediately before burning. For this purpose the DI-CHG.2 direct injector model by BorgWarner was used. This injector operated at 35 barG and 20 barG as maximum and minimum upstream pressures respectively; a 5.8 g/s flow rate; and a maximum tip nozzle temperature of 250 ◦C. Experiments were performed using a high-pressure and hightemperature visualization vessel available at our facility. The combustion mixture prior to burning (spray) was visually controlled by the single-pass high-speed Schlieren technique. Images were used to study the spray penetration (S) and spray volume (V). Several parameters were considered to perform the experiments such as the injection pressure (Pinj) chamber temperature (Tch) and the injection energizing time (Tinj). With pressure ratio and injection time being the parameters commonly used in jet characterization the addition of temperature formed a more comprehensive group of parameters that should generally aid in the characterization of this type of gas jets as well as the understanding of the combined effect of the rate of injection on the overall outcome. It was observed that the increase in injection pressure (Pinj) increased the spray penetration depth and its calculated volume as well as the amount of mass injected inside the chamber according to the ROI results; furthermore it was also observed that with a pressure difference of 20 bar (the minimum required for the proper functioning of the injector used) cyclic variability increased. The variation in temperature inside the chamber had less of an impact on the spray shape and its penetration; instead it determined the velocity at which the spray reached its maximum length. In addition the injection energizing time had no effect on the spray penetration.

In recent years global efforts towards a future with sustainable energy have intensified the development of renewable energy sources (RESs) such as offshore wind solar photovoltaics (PVs) hydro and geothermal. Concurrently green hydrogen produced via water electrolysis using these RESs has been recognized as a promising solution to decarbonizing traditionally hard-to-abate sectors. Furthermore hydrogen storage provides a long-duration energy storage approach to managing the intermittency of RESs which ensures a reliable and stable electricity supply and supports electric grid operations with ancillary services like frequency and voltage regulation. Despite significant progress the hydrogen economy remains nascent with ongoing developments and persistent uncertainties in economic technological and regulatory aspects. This paper provides a comprehensive review of the green hydrogen value chain encompassing production transportation logistics storage methodologies and end-use applications while identifying key research gaps. Particular emphasis is placed on the integration of green hydrogen into both grid-connected and islanded systems with a focus on operational strategies to enhance grid resilience and efficiency over both the long and short terms. Moreover this paper draws on global case studies from pioneering green hydrogen projects to inform strategies that can accelerate the adoption and large-scale deployment of green hydrogen technologies across diverse sectors and geographies.

Liquid hydrogen has the potential to significantly reduce in-flight carbon emissions in the aviation industry. Among the most promising aircraft configurations for future hydrogen-powered aviation are the blended wing body and the pure flying wing configurations. However their tapered and flattened airframe designs pose a challenge in accommodating liquid hydrogen storage tanks. This paper presents a design guide to tapered conformable pressure tanks for liquid hydrogen storage. The proposed tank configurations feature a multi-bubble layout and are subject to low internal differential pressure. The objective is to provide tank designers with simple geometric rules and practical guidelines to simplify the design process of tapered multi-bubble pressure tanks. Various tank configurations are discussed starting with a simple tapered two-bubble tank and advancing to more complex tapered configurations with a multi-segment and multi-bubble layout. A comprehensive design methodology is established providing tank designers with a step-by-step design procedure and highlighting the practical guidelines in each step of the design process.

This study aims to elucidate the behavior of diffusible hydrogen and delayed fracture in martensitic steel with 1500 MPa strength during automotive painting process and under vehicle service conditions. A sequential process of automotive pretreatment line and vehicle service environment is simulated to evaluate the hydrogen pick up in each process. In case of the automotive painting line the absorption of hydrogen is within the common range in the process of phosphating treatment and electrodeposition. The baking process plays an effective role for desorbing the diffusible hydrogen absorbed during the automotive pre-treatment such as zinc-phosphating and electrodeposition process. In case of the corrosion environment under the automotive driving conditions hydrogen induced delayed fracture is accelerated as the exposure time increases. Further it is clarified that severe plastic deformation are the significant factors for hydrogen induced delayed fracture under with low pH value and present of chloride ion in a chemical solution parameter. In summary hydrogen is transported constantly during electrodeposition sequential line process of automobile manufacturing below the hydrogen content of 0.5 ppm which is not critical value for leading to hydrogen delayed fracture based on results of slow strain rate tensile tests. However exposure to extreme conditions under service environment of vehicle such as acidic solution and chloride chemistry solution that result in high level of hydrogen absorption severe plastic deformation in the sheared edge and constantly applied internal or external stresses can cause the hydrogen induced delayed fracture in the fully martensitic steels.

Water electrolysis is considered as an important technology for an increased renewable energy penetration. This perspective on low-temperature water electrolysis joins the dots between the interdisciplinary fields of fundamental science describing physicochemical processes engineering for the targeted design of cell components and the development of operation strategies. Within this aim the mechanisms of ion conduction gas diffusion corrosion and electrocatalysis are reviewed and their influence on the optimum design of separators electrocatalysts electrodes and other cell components are discussed. Electrocatalysts for the water splitting reactions and metals for system components are critically accessed towards their stability and functionality. On the basis of the broad scientific analysis provided challenges for the design of water electrolyzers are elucidated with special regard to the alkaline or acidic media of the electrolyte.