Greece

Hydrogen dispersion in stagnant environment resulting from blowdown of a vessel storing the gas at cryogenic temperature is simulated using different CFD codes and modelling strategies. The simulations are based on the DISCHA experiments that were carried out by Karlsruhe Institute of Technology (KIT) and Pro-Science (PS). The selected test for the current study involves hydrogen release from a 2.815 dm3 volume tank with an initial pressure of 200 Read More

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 experi Read More

Comparison of Computational Fluid Dynamics (CFD) predictions with measurements is presented for cryo-compressed hydrogen vertical jets. The stagnation conditions of the experiments are characteristic of unintended leaks from pipe systems that connect cryogenic hydrogen storage tanks and could be encountered at a fuel cell refuelling station. Jets with pressure up to 5 bar and temperatures just above the saturation liquid temperature were ex Read More

The present review provides a catalogue of relevant renewable energy (RE) technologies currently available (regarding the 2030 scope) and to be available in the transition towards 2050 for the decarbonisation of Energy Intensive Industries (EIIs). RE solutions have been classified into technologies based on the use of renewable electricity and those used to produce heat for multiple industrial processes. Electrification will be key thanks to the gradual decrease Read More

The different CFD tools used by the NoE HySafe partners are applied to a series of integral complex Standard Benchmark Exercise Problems (SBEPs). All benchmarks cover complementarily physical phenomena addressing application relevant scenarios and refer to associated experiments with an explicit usage of hydrogen. After the blind benchmark SBEPV1 and SBEPV3 with subsonic vertical release in a large vessel and in a garage like facility SBE Read More

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 propertie Read More

In the present work CFD simulations of a hydrogen deflagration experiment are performed. The experiment carried out by KIT was conducted in a 1 m3 enclosure with a square vent of 0.5 m2 located in the center of one of its walls. The enclosure was filled with homogeneous hydrogen-air mixture of 18% v/v before ignition at its back-wall. As the flame propagates away from the ignition point unburned mixture is forced out through the vent. This mixtur Read More

The rapid development of science technology and engineering in the 21st century has offered a remarkable rise in our living standards. However at the same time serious environmental issues have emerged such as acid rain and the greenhouse effect which are associated with the ever-increasing need for energy consumption 85% of which comes from fossil fuels combustion. From this combustion process except for energy the main greenhouse gases-carb Read More

Atomic hydrogen produced by corrosion of a low-carbon steel in NaCl – Water solution may markedly affect its certain tensile mechanical and magnetic properties in a complex and peculiar manner. This influence was investigated by employing the intrinsic micromagnetic emission (ME)-response as well as tensile mechanical response of this ferromagnetic material and also by introduction a relevant measurement parameter of specific micromagneti Read More

This paper explores the alternative roles hydrogen can play in the future European Union (EU) energy system within the transition towards a carbon-neutral EU economy by 2050 following the latest policy developments after the COP21 agreement in Paris in 2015. Hydrogen could serve as an end-use fuel a feedstock to produce carbon-neutral hydrocarbons and a carrier of chemical storage of electricity. We apply a model-based energy system analys Read More

Hydrogen cars are expected to play an important role in a decarbonised clean-transport future. Safety issues arise though in tunnels due to the possibility of accidental release and accumulation of hydrogen. This Computational Fluid Dynamics (CFD) study focuses on the effect of tunnel inclination and ventilation on hydrogen dispersion. A horseshoe shaped tunnel of 200 m length is considered in all seventeen cases examined. In most cases hydrogen is rel Read More

Gasification of municipal solid waste (MSW) with subsequent utilization of syngas in gas engines/turbines and solid oxide fuel cells can substantially increase the power generation of waste-to-energy facilities and optimize the utilization of wastes as a sustainable energy resources. However purification of syngas to remove multiple impurities such as particulates tar HCl alkali chlorides and sulfur species is required. This study investigates the feasibility of high t Read More

During the past few years hydrogen use has come to be considered as an alternative energy carrier in a future decarbonized world. Many developed nations are undergoing a shift towards low-carbon energy sources driven by the excessive reliance on fossil fuels and the detrimental effects of climate change. This study aims to investigate the potential for hydrogen deployment in the Greek energy market during the next few decades. In this context green hy Read More

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 towa Read More

In April 2018 the International Maritime Organisation adopted an ambitious plan to contribute to the global efforts to reduce the Greenhouse Gas emissions as set by the Paris Agreement by targeting a 50% reduction in shipping’s Green House Gas emissions by 2050 benchmarked to 2008 levels. To meet these challenging goals the maritime industry must introduce environmentally friendly fuels with negligible or low SOX NOX and CO2 emissions. Ammoni Read More

The European Hydrogen Strategy and the new « Fit for 55 » package indicate the urgent need for the alignment of policy with the European Green Deal and European Union (EU) climate law for the decarbonization of the energy system and the use of hydrogen towards 2030 and 2050. The increasing carbon prices in EU Emission Trading System (ETS) as well as the lack of dispatchable thermal power generation as part of the Coal exit are expected to e Read More

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 proje Read More

For lignite intense regions such as the case of Western Macedonia (WM) the production and utilization of green hydrogen is one of the most viable ways to achieve near zero emissions in sectors like transport chemicals heat and energy production synthetic fuels etc. However the implementation of each technology that is available to a respective sector differs significantly in terms of readiness and the current installation scale of each technology. T Read More

Current technological improvements are yet to put the world on track to net-zero which will require the uptake of transformative low-carbon innovations to supplement mitigation efforts. However the role of such innovations is not yet fully understood; some of these ‘miracles’ are considered indispensable to Paris Agreement-compliant mitigation but their limitations availability and potential remain a source of debate. We evaluate such potentially game-chan Read More

The role of hydrogen as a clean energy source is a promising but also a contentious issue. The global energy production is currently characterized by an unprecedented shift to renewable energy sources (RES) and their technologies. However the local and environmental benefits of such RES-based technologies show a wide variety of technological maturity with a common mismatch to local RES stocks and actual utilization levels of RES exploit Read More

Accurate estimation of mass flow rate and release conditions is important for the design of dispersion and combustion experiments for the subsequent validation of CFD codes/models for consequence assessment analysis within related risk assessment studies and for associated Regulation Codes and Standards development. This work focuses on the modelling of the discharge phase of the recent large scale LH2 release and dispersion experime Read More

Island energy systems are becoming an important part of energy transformation due to the growing needs for the penetration of renewable energy. Among the possible systems a combination of different energy generation technologies is a viable option for local users as long as energy storage is implemented. The presented paper describes an energy-economic assessment of an island system with a photovoltaic field small wind turbine wood chip gasifier Read More

The exploitation of renewable energy sources in the building sector is a challenging aspect of achieving sustainability. The incorporation of a proper storage unit is a vital issue for managing properly renewable electricity production and so to avoid the use of grid electricity. The present investigation examines a zero-energy residential building that uses photovoltaics for covering all its energy needs (heating cooling domestic hot water and appliances-lighti Read More

In terms of energy generation and consumption ships are autonomous isolated systems with power demands varying according to the type of ship: passenger or commercial. The power supply in modern ships is based on thermal engines-generators which use fossil fuels marine diesel oil (MDO) and liquefied natural gas (LNG). The continuous operation of thermal engines on ships during cruises results in increased emissions of polluting gases Read More

Clean energy technological innovations are widely acknowledged as a prerequisite to achieving ambitious longterm energy and climate targets. However the optimal speed of their adoption has been parsimoniously studied in the literature. This study seeks to identify the optimal intensity of moving to a green hydrogen electricity sector in Greece using the OSeMOSYS energy modeling framework. Green hydrogen policies are evaluated first on the basis Read More