The UAE aviation sector is vital for its economy and is forecast to grow substantially in the coming decades, increasing thereby fuel consumption. At the same time, the country is committed to cutting greenhouse gas emissions to mitigate climate change. Liquid green hydrogen is expected to emerge as an important aviation fuel in the future. The UAE can use its vast solar energy resources to produce cost-competitive hydrogen at scale, securing so its aviation fuel supply. This development, however, needs several decades to materialize. The PV farms needed to produce the electricity for water electrolysis need yet to be constructed. The infrastructure to produce, liquify, store and transport hydrogen is yet to unfold. Hydrogen-powered aircraft need to yet evolve from the current small scale demonstration projects to long-haul commercial airplanes. It is realistically by 2050 when hydrogen gains momentum as aviation fuel and by 2070 when it becomes market dominant. This paper details why and how liquid green hydrogen will find its way as aviation fuel in the UAE and provides the strategy and policy recommendations to facilitate this development. Furthermore, based on the lessons learned from this case study, the implications of the transition to liquid green hydrogen at global scale are highlighted.

The building sector is responsible for 40% of primary energy consumption, with heating/cooling covering the most significant portion. Thus, passive heating/cooling applications have gained significant ground during the last three decades, with many research activities on the subject. Among passive cooling/heating applications, ground cooling (especially earth-to-air heat exchangers) has been highlighted as a remarkably attractive technological research subjects because of its significant contribution to the reduction of heating/cooling energy loads; the improvement of indoor thermal comfort conditions; and the amelioration of the urban environment. This paper presents a holistic review of state-of-the-art research, methodologies, and technologies of earth-to-air heat exchangers that help achieve energy conservation and thermal comfort in the built environment. The review covers the critical subject of the thermal performance of earth-to-air heat exchanger systems; experimental studies and applications; parametric studies for investigating the impact of their main characteristics on thermal efficiency; and recent advances and trends including hybrid technologies and systems. The models describing the thermal performance of earth-to-air heat exchangers systems were classified in numerical, analytical, and data-driven; their main theoretical principles were presented; and experimental validation was mentioned when carried out. System parameters were grouped into three categories: system design, soil types, and soil surface coverage. System design parameters, especially length and burial depth, bore the most important influence on the thermal efficiency of the system. The paper was rounded up with an economic assessment of system application, and the conclusions highlighted the need for more experimental work including laboratory simulators.

The Residential and Industrial zones as is, rely heavily, if not exclusively, on Hydrocarbons. Hydrocarbon thermal machinery such as Spark Ignition-Compression Ignition engines, Gasoline-Diesel generators, Coal-Lignite gasifiers, residential diesel-powered heating systems, Pyrolysis units and so on, are commonly met all around the planet. Such technology practically oxidizes Hydrocarbons to produce either heat, steam or useful mechanical work depending on the application, though energy losses are not, by any means, insignificant. Advanced material processing is an industrial sector who’s energy demand is significant and it is important for the general public to come to terms with the fact that by implementing Hydrogen technology to power such plant while at the same time improving the energy equilibrium of houses(advanced materials), communities would be taking major steps towards Climate Change effects debilitation. The downside of Hydrocarbon thermochemical exploitation can be described by the limited resources-reserves and the gaseous pollutant emissions (CO2, CO, NOx, SOx). In recent years, the Industrial zone as a whole has began taking a turn towards Electrification without having established the necessary infrastructure to support such a transition. Indicatively, at current rate of production, dead Lithium-Ion batteries are projected to reach as high as 11,000 metric tons by 2030, yet there is no recycling scheme in place, not to mention the prospect of that number rising even more, given the recent e-mobility trend. As it pertains to Electrification, such powertrains-machinery require electricity and a battery. Electricity production is mainly achieved through Coal-Lignite gasification, Batteries require metals, among others, for manufacturing, meaning that up-on mining, local water resources are contaminated, another very important ‘aspect’ of Lithium(per say) mining is that child labor is often associated with such processes, a truly despicable act. All of the above paint a crystal-clear picture as to how ‘environmentally friendly’ reckless-rushed Electrification really is. Climate Change is up-on us and it’s effects on the planet are obvious, the most important of which is glacier melting due to rising of the global Temperature. The COVID-19 crisis is a sign of what could come from glacier melting could as ice contains potentially harmful-toxic to humans, biological entities that are sure to be introduced to the general public if we were to continue exploiting mineral resources. Purpose of this paper is to provide a general overview of the technology around Hydrogen.

“Black”, “grey” or “brown” refer emissions to the production of hydrogen from coal, natural gas and lignite, respectively. “Blue” is commonly used for the production of hydrogen from fossil fuels with CO2 reduced by the use of carbon capture, use and Storage (CCUS). “Green” is a term applied to production of hydrogen from renewable electricity. In general, there are no established colors for hydrogen from biomass, nuclear or different varieties of grid electricity. As the environmental impacts of each of these production routes can vary considerably by energy source, region and type of CCUS applied. Building novel blue communities need to be oriented in buildings. Stationary fuel cells are units that provide electricity (and sometimes heat) but are not designed to be moved. These include combined heat and power (CHP), uninterruptible power systems (UPS) and primary power units. The heat produced as a by-product of combined heat and power is used to cover part of the buildings heat demand. The mostly electricity-led mode of operation results in a low thermal output from fuel cell heating systems. The remaining heat requirement of the building is covered by an additional heating system, e.g. a condensing boiler. For that reason, fuel cells are particularly suitable for buildings with a low space heating requirement, such as low-energy or nearly zero-energy buildings. In buildings with a higher space heating requirement, hybrid fuel cell heating systems, comprising a fuel cell and a condensing boiler to cover peak heating requirements, are used. Stationary fuel cells in the output range up to 10 kWe are usually PEM or SO fuel cells. The typical CHP output range for houses and apartment buildings is 0.7 to 5 kWe. Probably the biggest advantage of fuel cells over thermal power processes is the direct electrochemical conversion during electricity and heat generation and the associated higher electrical efficiency. In combined mode, i.e. electrical and thermal, fuel cells can achieve efficiencies of up to 95 %. The electrical efficiency is up to 45 %. Furthermore, fuel cell systems are characterized by high efficiencies over all load points, they are quiet, have low maintenance costs and operate (locally) emission-free.

In recent decades, the steady increase of energy consumption from building construction and operations cause atmospheric pollution and significant financial burden, mainly due to the high costs imposed from energy production. This study examines ways under which modern designs of a building can be applied on construction and domestication while following conventional methods of construction, compared to a building that has been constructed and domesticated under bioclimatic architecture. Particularly, two buildings were investigated in terms of the energy consumption incurred, being built on the same seaside area and period of construction and at adjacent plots of the same distance from sea for ease of comparison. The first building (A1) was constructed under the principles of bioclimatic architecture, being also facilitated with green and smart technologies. The second building (A2) was constructed under conventional construction techniques. The energy efficiency of both buildings was calculated by the “TEE KENAK” software, while specific parameters were recorded. Energy classifications of both buildings were valued and a proposed scenario and interventions unveiled the energy classification upgrading from A2 to A1. Our analysis revealed, as also found in the literature, that during thermal energy oscillating conditions, corresponding relative humidity stresses were observed, indicating that the vapor pressure handling should be taken into account towards comfort. The preliminary incremental cost evaluation and comparison of A1 and A2 energy upgrading under the criterion of simple payback period were critically discussed.

Nd-xZrxFe(10)Si(2) alloys have been prepared in the tetragonal ThMn12-type structure by arc-melting and melt spinning and then nitrogenated to improve their magnetic properties. For x = 0.4 and 0.6 the Curie temperature and magnetic anisotropy fields increases from 280 to 300 degrees C to about 390 degrees C and from 2.8 to 3 Tesla to 4.5-5 Tesla respectively. The saturation magnetization remains almost unchanged. The nitrogenated powders were processed by Spark Plasma Sintering (SPS) leading to compact pellets, which retain the full Nitrogen content and magnetic properties up to 600 degrees C, but segregated Fe-Si at elevated temperatures. Nitrogenation and SPS processing are, therefore, appropriate for sintering metastable materials such as (NdZr)Fe10Si2 into compact material without loosing functional properties. This opens a way towards a new family of permanent magnets, lean of critical raw materials. (C) 2019 Published by Elsevier B.V.

Hydrogen storage materials based on the stoichiometry Mg(Ni1-xMnx)(2) have been synthesized by High Energy Ball Milling (HEBM) and studied as potential candidate materials for solid state hydrogen storage. The microstructures of the as-cast and the milled alloys were characterized by means of X-ray Powder Diffraction (XRD) and Scanning Electron Microscopy (SEM) both prior and after the hydrogenation process. The storage characteristics (Pressure-Composition-Temperature isotherms) and the sorption kinetics obtained by a commercial and automatically controlled Sievert-type apparatus. The X-ray results showed that the substitution of Mn over Ni could eliminate and inhibit the MgNi2 phase. The calculation of the average crystallite size showed that the increase of the amount of Mn can reduce the size at the early stages, but for Mn content higher than 0.25 the crystallite size increases, while the microstrain levels decreased monotonically. The hydrogenation and dehydrogenation measurements took place at several temperatures (150-200-250-300 degrees C). The results showed that the kinetics for both the hydrogenation and dehydrogenation can be fast for operation at temperatures between 250 and 300 degrees C, but for temperatures below 200 degrees C the hydrogenation process is very slow, and the dehydrogenation process cannot be achieved. (C) 2019 Elsevier Ltd. All rights reserved.

A breakthrough in the process method has been developed by combined considerations in the demands of "Shell Eco Marathon" using finite element modelling (FEM). Ultrafast calculations have revealed novel chassis development. The most critical factors in designing the new chassis are the reduction of the weight, the improvement of strength and stiffness, the reduction of material and the manufacturing cost. The simple structural surfaces (SSS) method was used for an electric car so as the type of loading conditions which are applied to the chassis structure to be predicted. Afterwards, a new design approach for a lightweight carbon-fibre reinforced polymer (CFRP) monocoque chassis is proposed which conforms to structural, ergonomic, safety and aesthetic requirements. The SSS method in conjunction with the creation of the chassis load calculator (CLC) model and both the specialised and integrated methodology of the processing procedure through FEM, have attained the overcoming of the time consuming conceptual design process.

The increasing demand for energy efficient electric cars, in the automotive sector, entails the need for improvement of their structures, especially the chassis, because of its multifaceted role on the vehicle dynamic behaviour. The major criteria for the development of electric car chassis are the stiffness and strength enhancement subject to mass reduction as well as cost and time elimination. Towards this direction, this work indicates an integrated methodology of developing an electric car chassis considering the modeling and simulation concurrently. The chassis has been designed in compliance with the regulations of Shell Eco Marathon competition. This methodology is implemented both by the use of our chassis load calculator (CLC) model, which automatically calculates the total loads applied on the vehicle’s chassis and by the determination of a worst case stress scenario. Under this extreme stress scenario, the model’s output was evaluated for the chassis design and the FEA method was performed by the pre-processor ANSA and the solver Ansys. This method could be characterized as an accurate ultrafast and cost-efficient method.

Hydrogen is the lightest of gases and possesses the lowest density.However at ambient temperature and pressure it occupies a large volume.This necessitates compressing it at high pressures up to 800 Bars to minimize the volume.The immense interest generated by hydrogen comes from the fact that it has the best energy per weight ratio of all fuels and the ecological nature of the combustion product.From the pedagogical point of view, it is also the most taught and involved in research, in particular in quantum mechanics.This aspect is treated in this article in order to solve the problem of storage of the hydrogen by minimizing losses.The solutions envisaged are, first, the improvement of the theory to understand the physical phenomena that occur in the physical system, especially the resolution of the transcendental equation, and then the means of perfecting the materials constituting the cavity.Quantum scale investigations began with solving the Schrodinger equation at threedimensional spherical symmetry, taking into account the boundary conditions of Victor Gustave Robin on the inner walls of the envelope.The clean energies that are stored in a spherical-shaped cavity have been modeled theoretically by solving the transcendental equation.The last part of the article is devoted to the thermodynamic properties of the hydrogen gas, particularly the dependence of the energy with the pressure and the temperature.

Hydrogen as fuel has been a promising technology toward climate change mitigation efforts. To this end, in this paper we analyze the contribution of hydrogen technology to our future environmental goals. It is assumed that hydrogen is being produced in higher efficiency across time and this is simulated on Global Change Assessment Model ( GCAM ). The environmental restrictions applied are the expected emissions representative concentration pathways ( RCP ) 2.6, 4.5, and 6.0. Our results have shown increasing hydrogen production as the environmental constraints become stricter and hydrogen more efficient in being produced. This increase has been quantified and provided on open access as Supporting Information to this manuscript.

A fully validated with solid experimental results numerical study regarding the hydrogenation process of rectangular metal hydride beds under effective internal heat management is presented and analysed. Three different geometries equipped with plain embedded heat management tubes are introduced and examined. For each geometry, five different values of metal hydride thickness are studied and additionally, the effect of the coolant flow is examined in terms of different values of heat transfer coefficient [W/m(2)K]. To evaluate the effect of the heat management process, a variable named as Non-Dimensional Conductance (NDC) is analysed and studied. Furthermore, three different materials are introduced, two "conventional" AB(5) intermetallics and a novel AB(2)-based Laves phase intermetallic. According to the results, the optimum value for the metal hydride thickness was found to be 10.39 mm, while the optimum value for the heat transfer coefficient was 2000 [W/m(2)K]. For the above optimum conditions, the performance of the novel AB(2)-based Laves phase intermetallic showed the fastest hydrogenation kinetics compared to the other two AB(5) intermetallics indicating that is a powerful storage material for stationary applications. Crown Copyright (C) 2017 Published by Elsevier Ltd. All rights reserved.

In the current work, a parametric numerical analysis of MmNi4.6Al0.4 is studied during the hydrogenation process; under effective heat management. A fully validated with solid experimental results mathematical model including the heat, mass and momentum conservation equations is introduced, described and incorporated on a Multiphysics software (COMSOL Multiphysics). The target of the current study was the storage of 200g of hydrogen per hydrogenation/dehydrogenation cycle within 5000s. The heat management during the hydrogenation process was performed by the usage of plain-embedded cooling tubes in combination with extended surfaces. The parameters examined in the current work were; the fin thickness, the fin number (metal hydride thickness) and the coolants’ flowrate within the tubes. A non-dimensional parameter was utilised for the evaluation of the heat management process. The results showed that the optimum fin number was 60, in combination with fin thickness 5-8mm and the value of the heat transfer coefficient 2000-5000 Wm-2K-1.

The development of the chassis for the hydrogen fuel cell powered car has been involved in the designing and manufacturing aspects, while taking into consideration the mass, strength, stiffness, centre of gravity (COG), and manufacturing cost requirements. Towards this direction, a chassis design is proposed employing a space frame structure and constructed by an aluminium alloy with great strength. The structural design has been derived through the lightweight engineering approaches in conjunction with the part consolidation, Design for Assembly (DFA) and Design for Manufacture methods. Moreover, it has been performed in compliance with the safety regulations of the Shell Eco Marathon racing competition. The material’s principal characteristics are the great strength, the low mass, as well as the great workability, machinability, and weldability. Following the national and global environmental issues, the recyclable characteristics of the aluminium alloy are an extra asset. Furthermore, the existence of aluminium alloy manufacturers around the fabricating area provides low cost supply and fast delivery benefits. The integration of the fuel cell powered vehicle is obtained through the designing and the manufacturing processes of the chassis and the parts fitted on the chassis. The manufacturing procedures are described thoroughly; mainly consisting of the cutting and welding processes and the assembling of the parts that are fitted on the chassis. Additionally, the proper welding parameters for the custom chassis design are investigated and are selected after deductive reasoning. The quality control of the weld joints is conducted by non-destructive methods (NDT) ensuring the required structural properties of the welds. A combination of the selected material, the specific type of the chassis, and the manufacturing processes lead to construction simplicity in a low manufacturing cost by using the existing laboratory equipment. Furthermore, the designing and manufacturing parameters lead to a stiff with a low centre of gravity, and the most lightweight chassis of the urban concept category at the Shell Eco Marathon race.

The electricity sector is among the main contributors to carbon emissions. This sector has the potential to reduce its carbon emissions through producing electric energy from zero-emitting facilities and optimizing consumption to better accommodate low-carbon emissions. The use of hydrogen combined with smart grids, as analyzed in this manuscript, can substantially contribute to climate change mitigation.

Energy is a fundamental ingredient in economic development and energy consumption is an index of prosperity and the standard of living. The consumption of energy has increased significantly in the last number of decades, as the standard of living has improved. Renewable energy is a sustainable and clean source of energy derived from nature. Renewable energy technology is one of the solutions, which produces energy by transforming natural resources into useful energy forms. When you do something for the first time in the world, you never attain a perfect product or solution from the start. In Central Greece Lamia city, we are the first to design and implement an off-grid energy system using hydrogen energy storage technology and phase change materials for a house residence. The action plan for energy efficiency, a series of directives and incentive mechanisms, mandatory energy certification of buildings, indicate the urgent need to reduce energy consumption in buildings, which results in a more comfortable living, long service life of buildings, which in turn preserves the environment.

Thermoelectric materials may be used in devices as thermoelectric “air conditioner” in a smart house for improved energy efficiency. Energy harvesting uses ambient energy to generate electricity. It provides potentially low-cost, maintenance-free, long-life equipment by reducing the need for batteries or power chords. Energy harvesting (EH) is also known as power harvesting or energy scavenging. EH is considered to give benefits related to environmental friendliness, safety, security, convenience and affordability. EH can be used for brand enhancing. Technically, it can be used to make new things possible depending on visionary engineering. The variety of thermoelectric (TE) materials that can be used in energy harvesting is quite large, and the optimal material for a given application depends mainly on the temperature range in which the material is to be used. In this work we study the development and characterization of thermoelectric materials which were prepared by two different method, which were: a) ball-milling followed by sintering and b) ball-milling, microwave synthesis, high energy planetary ball milling, and sintering. Finally, we study the thermoelectric properties, calculate the band gaps and the ZT for the thermoelectric materials.

The dehydrogenation behaviour of a cylindrical MgH2 metal hydride tank is examined by taking into account five different heat management scenarios. A three-dimensional mathematical model, validated with experimental results is utilized to simulate the dehydrogenation process of an up-scale cylindrical Mg metal hydride tank. The scope of this study is to examine the dehydrogenation kinetics of 100 g of H2 that have been stored to the tank. Five different heat management scenarios are examined and compared to each other: a base case where the heat source for the dehydrogenation process is an external heater (external jacket) surrounding the tank. The second case examines the effect of the radiation heat transfer arising from an operating Solid Oxide Fuel Cell (SOFC) to the metal hydride tank as a possible heat source for the dehydrogenation procedure. The third scenario takes into account the usage of internal heating tubes within the tank and the case of using 8-12-16-20 and 24 co-central tubes. For the fourth scenario, the optimum number of the co-central tubes from the previous case is used in combination with interior extended surfaces (fins). Finally, the last scenario involves the combination of the interior extended surfaces with the external jacket as a possible heat management technique. The results showed that when using the external heating jacket and the radiation heat from the SOFC the time for the hydride to release all the stored hydrogen (100 g) is greater than 15 min, while when using embedded heating tubes with oil as the flowing fluid the time is almost 7 min and when combine the embedded heating tubes with extended surfaces the time for the fully release of hydrogen can reduce more to 2 min. Finally, when combining the extended surfaces with the external heating jacket the total discharge time is less than 4 min.

Energy has always been the driving force in the technological and economic development of societies. The consumption of a significant amount of energy is required to provide basic living conditions of developed countries (heating, transportation, lighting, etc.). Today energy supply has a considerable impact on the environment, since it is fuelled by the burning of fossil fuels. In addition to this, the fossil fuel reserves are decreasing while the demand for energy is rapidly rising. Climate change, the depletion and geographical segregation of fossil fuel resources, health related issues as well as energy poverty constitute the driving forces towards the pursuit of alternative energy sources. In addition, countries with no access to oil reserves are being dependent from other countries for their energy supply, with a strong impact on politics and financial issues.