Greece

Purpose- To present an overview of the research and development carried out in a European funded framework 7 (FP7) project called SafeHPower for the implementation of neutron radiography to inspect fatigue cracks in vehicle and storage hydrogen fuel tanks. Project background– Hydrogen (H2) is the most promising replacement fuel for road transport due to its abundance efficiency low carbon footprint and the absence of harmful emissions. For the mass market of hydrogen to take off the safety issue surrounding the vehicle and storage hydrogen tanks needs to be addressed. The problem is the residual and additional stresses experienced by the tanks during the continuous cyclic loading between ambient and storage pressure which can result in the development of fatigue cracks. Steel tanks used as storage containers at service stations and depots and/or the composite tanks lined with steel are known to suffer from hydrogen embrittlement (HE). Another issue is the explosive nature of hydrogen (when it is present in the 18-59% range) where it is mixed with oxygen which can lead to catastrophic consequences including loss of life. Monitoring systems that currently exist in the market impose visual examination tests pressure tests and hydrostatic tests after the tank installation [1] [2]. Three inspection systems have been developed under this project to provide continuous monitoring solutions. Approach and scope- One of the inspection systems based on the neutron radiography (NR) technology that was developed in different phases with the application of varied strategies has been presented here. Monte Carlo (MCNP) simulation results to design and develop a bespoke collimator have been presented. A limitation of using an inertial electrostatic Deuterium-Tritium (D-T) pulsed neutron generator for fast neutron radiography has been discussed. Radiographs from the hydrogen tank samples obtained using thermal neutrons from a spallation neutron source at ISIS Rutherford laboratory UK have been presented. Furthermore radiograph obtained using thermal neutrons from a portable D-T neutron generator has been presented. In conclusion a proof in principle has been made to show that the defects in the hydrogen fuel tank can be detected using thermal neutron radiography.

A common sustainability issue arising in production systems is the efficient use of resources for providing goods or services. With the increased interest in a hydrogen (H2) economy the life-cycle environmental performance of H2 production has special significance for assisting in identifying opportunities to improve environmental performance and to guide challenging decisions and select between technology paths. Life cycle impact assessment methods are rapidly evolving to analyze multiple environmental impacts of the production of products or processes. This study marks the first step in developing process-based streamlined life cycle analysis (LCA) of several H2 production pathways combining life cycle impacts at the midpoint (17 problem-oriented) and endpoint (3 damage-oriented) levels using the state-of-the-art impact assessment method ReCiPe 2016. Steam reforming of natural gas coal gasification water electrolysis via proton exchange membrane fuel cell (PEM) solid oxide electrolyzer cell (SOEC) biomass gasification and reforming and dark fermentation of lignocellulosic biomass were analyzed. An innovative aspect is developed in this study is an analysis of water consumption associated with H2 production pathways by life-cycle stage to provide a better understanding of the life cycle water-related impacts on human health and natural environment. For water-related scope Water scarcity footprint (WSF) quantified using Available Water Remaining (AWARE) method was applied as a stand-alone indicator. The paper discusses the strengths and weaknesses of each production pathway identify the drivers of environmental impact quantify midpoint environmental impact and its influence on the endpoint environmental performance. The findings of this study could serve as a useful theoretical reference and practical basis to decision-makers of potential environmental impacts of H2 production systems.

The present research focuses on the investigation of an in situ hydrogen charging effect during Crack Tip Opening Displacement testing (CTOD) on the fracture toughness properties of X65 pipeline steel. This grade of steel belongs to the broader category of High Strength Low Alloy Steels (HSLA) and its microstructure consists of equiaxed ferritic and bainitic grains with a low volume fraction of degenerated pearlite islands. The studied X65 steel specimens were extracted from pipes with 19.15 mm wall thickness. The fracture toughness parameters were determined after imposing the fatigue pre-cracked specimens on air on a specific electrolytic cell under a slow strain rate bending loading (according to ASTM G147-98 BS7448 and ISO12135 standards). Concerning the results of this study in the first phase the hydrogen cations’ penetration depth the diffusion coefficient of molecular and atomic hydrogen and the surficial density of blisters were determined. Next the characteristic parameters related to fracture toughness (such as J KQ CTODel CTODpl) were calculated by the aid of the Force-Crack Mouth Open Displacement curves and the relevant analytical equations.

An  inter-comparison  among  partners’  CFD  simulations  has  been  carried  out  within  the  EU-funded project PRESLHY to investigate the dispersion of the mixture cloud formed from large scale liquid hydrogen release. Rainout experiments performed by Health and Safety Executive (HSE) have been chosen for the work. From the HSE experimental series trial-11 was selected forsimulation due to its conditions where  only  liquid  flow  at  the  nozzle  was  achieved.   During  trial-11  liquid  hydrogen  is spilled horizontally 0.5 m above a concrete pad from a 5 barg tank pressure through a 12 mm (1/2 inch) nozzle. The dispersion takes place outdoors and thus it is imposed to variant wind conditions. Comparison  of  the  CFD  results  with  the   measurements  at  several  sensors  is  presented  and  useful conclusions are drawn.

To limit the global temperature change to no more than 2 ◦C by reducing global emissions the European Union (EU) set up a goal of a 20% improvement on energy efficiency a 20% cut of greenhouse gas emissions and a 20% share of energy from renewable sources by 2020 (10% share of renewable energy (RE) specifically in the transport sector). By 2030 the goal is a 27% improvement in energy efficiency a 40% cut of greenhouse gas emissions and a 27% share of RE. However the integration of RE in energy system faces multiple challenges. The geographical distribution of energy supply changes significantly the availability of the primary energy source (wind solar water) and is the determining factor rather than where the consumers are. This leads to an increasing demand to match supply and demand for power. Especially intermittent RE like wind and solar power face the issue of energy production unrelated to demand (issue of excess energy production beyond demand and/or grid capacity) and forecast errors leading to an increasing demand for grid services like balancing power. Megawatt electrolyzer units (beyond 3 MW) can provide a technical solution to convert large amounts of excess electricity into hydrogen for industrial applications substitute for natural gas or the decarbonization of the mobility sector. The demonstration of successful MW electrolyzer operation providing grid services under dynamic conditions as request by the grid can broaden the opportunities of new business models that demonstrate the profitability of an electrolyzer in these market conditions. The aim of this work is the demonstration of a technical solution utilizing Pressurized Alkaline Electrolyzer (PAE) technology for providing grid balancing services and harvesting Renewable Energy Sources (RES) under realistic circumstances. In order to identify any differences between local market and grid requirements the work focused on a demonstration site located in Austria deemed as a viable business case for the operation of a largescale electrolyzer. The site is adapted to specific local conditions commonly found throughout Europe. To achieve this this study uses a market-based solution that aims at providing value-adding services and cash inflows stemming from the grid balancing services it provides. Moreover the work assesses the viability of various business cases by analyzing (qualitatively and quantitatively) additional business models (in terms of business opportunities/energy source potential grid service provision and hydrogen demand) and analyzing the value and size of the markets developing recommendations for relevant stakeholder to decrease market barriers.

The paper presents the first outcomes of the experimental numerical and theoretical studies performed in the funded by Fuel Cell and Hydrogen Joint Undertaking (FCH2 JU) project HyTunnel-CS. The project aims to conduct pre-normative research (PNR) to close relevant knowledge gaps and technological bottlenecks in the provision of safety of hydrogen vehicles in underground transportation systems. Pre normative research performed in the project will ultimately result in three main outputs: harmonised recommendations on response to hydrogen accidents recommendations for inherently safer use of hydrogen vehicles in underground traffic systems and recommendations for RCS. The overall concept behind this project is to use inter-disciplinary and inter-sectoral prenormative research by bringing together theoretical modelling and experimental studies to maximise the impact. The originality of the overall project concept is the consideration of hydrogen vehicle and underground traffic structure as a single system with integrated safety approach. The project strives to develop and offer safety strategies reducing or completely excluding hydrogen-specific risks to drivers passengers public and first responders in case of hydrogen vehicle accidents within the currently available infrastructure.

Integrated steelworks off-gases are generally exploited to produce heat and electricity. However further valorization can be achieved by using them as feedstock for the synthesis of valuable products such as methane and methanol with the addition of renewable hydrogen. This was the aim of the recently concluded project entitled “Intelligent and integrated upgrade of carbon sources in steel industries through hydrogen intensified synthesis processes (i3 upgrade)”. Within this project several activities were carried out: from laboratory analyses to simulation investigations from design development and tests of innovative reactor concepts and of advanced process control to detailed economic analyses business models and investigation of implementation cases. The final developed methane production reactors arerespectively an additively manufactured structured fixedbed reactor and a reactor setup using wash-coated honeycomb monoliths as catalyst; both reactors reached almost full COx conversion under slightly over-stoichiometric conditions. A new multi-stage concept of methanol reactor was designed commissioned and extensively tested at pilot-scale; it shows very effective conversion rates near to 100% for CO and slightly lower for CO2 at one-through operation for the methanol synthesis. Online tests proved that developed dispatch controller implements a smooth control strategy in real time with a temporal resolution of 1 min and a forecasting horizon of 2 h. Furthermore both offline simulations and cost analyses highlighted the fundamental role of hydrogen availability and costs for the feasibility of i 3 upgrade solutions and showed that the industrial implementation of the i 3 upgrade solutions can lead to significant environmental and economic benefits for steelworks especially in case green electricity is available at an affordable price.

The main objective of this work is the Large Eddy Simulation (LES) of hydrogen subsonic jets in order to evaluate modelling strategies and to provide guidelines for similar simulations. The ADREAHF code and the experiments conducted by Sandia National Laboratories are used for that purpose. These experiments are particularly ideal for LES studies because turbulent fluctuations have been measured which is something rare in hydrogen experiments. Hydrogen is released vertically from a small orifice of 1.91 mm diameter into an unconfined stagnant environment. Three experimental cases are simulated with different inlet velocity (49.7 76.0 and 133.9 m/s) which corresponds to transitional or turbulent flows. Hydrogen mass fraction and velocity mean values and fluctuations are compared against the experimental data. The Smagorinsky subgrid-scale model is mainly used. In the 49.7 m/s case the RNG LES is also evaluated. Several grid resolutions are used to assess the effect on the results. The amount of the resolved by the LES turbulence and velocity spectra are presented. Finally the effect of the release modelling is discussed.

An engineering tool is presented to predict steady state two-phase choked flow through a discharge line with variable cross section with account of friction and without wall heat transfer. The tool is able to predict the distribution of all relevant physical quantities along the discharge line. Choked flow is calculated using the possible-impossible flow algorithm implemented in a way to account for possible density discontinuities along the line. Physical properties are calculated using the Helmholtz Free Energy formulation. The tool is verified against previous experiments with water and evaluated against previous experiments with cryogenic two-phase hydrogen.

Extensive decarbonisation efforts result in major changes in energy demand for the extractive industry. In 2021 the extraction and primary processing of metals and minerals accounted for 4.5 Gt of CO2 eq. per year. The aluminium industry was responsible for 1.1 Gt CO2 eq. direct and indirect emissions. To reach the European milestone of zero emissions by 2050 a reduction of 3% annually is essential. To this end the industry needs to take a turn towards less impactful production practices coupling secondary production with green energy sources. The present work aims to comprehensively compare the lifecycle energy consumption and environmental performance of a secondary aluminium smelter employing alternative thermal and electricity sources. In this frame a comparative analysis of the environmental impact of different thermal energy sources namely natural gas light fuel oil liquified petroleum gas hydrogen and electricity for a secondary aluminium smelter is presented. The results show that H2 produced by renewables (green H2 ) is the most environmentally beneficial option accounting for −84.156 kg CO2 eq. By producing thermal energy as well as electricity on site H2 technologies also serve as a decentralized power station for green energy production. These technologies account for a reduction of 118% compared to conventionally used natural gas. The results offer a comprehensive overview to aid decision-makers in comparing environmental impacts caused by different energy sources.