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Energy demand of a transport sector has constantly been increasing in the recent years, consuming one third of the total final energy demand in the European Union (EU) over the last decade. A transition of this sector towards sustainable one is facing many challenges in terms of suitable technology and energy resources. Especially challenging transition is envisaged for heavy-weight, long-range vehicles and airplanes. A detailed literature review was carried out in order to detect the current state of the research on clean transport sector, as well as to point out the gaps in the research. In order to calculate the resources needed for the transition towards completely renewable transport sector, four main alternatives to the current fossil fuel systems were assessed and their potential was quantified, i.e. biofuels, hydrogen, synthetic fuels (electrofuels) and electricity. Results showed that electric modes of transport have the largest benefits and should be the main aim of the transport transition. It was calculated that 72.3% of the transport energy demand on the EU level could be directly electrified by the technology existing today. For the remaining part of the transport sector a significant demand for energy resources exists, i.e. 3069 TWh of additional biomass was needed in the case of biofuels utilization scenario while 2775 TWh of electricity and 925 TWh of heat were needed in the case of renewable electrofuels produced using solid oxide electrolysis scenario.

Hydrogen produced from renewables works as an energy carrier and as energy storage medium and thus hydrogen can help to overcome the intermittency of typical renewable energy sources. However, there is no comprehensive environmental performance study of hydrogen production and consumption. In this study, detailed cradle to grave life cycle analyses are performed in an isolated territory. The hydrogen is produced on-site by Polymer Electrolyte Membrane (PEM) water electrolysis based on electricity from wind turbines that would otherwise have been curtailed and subsequently transported with gas cylinder by road and ferry. The hydrogen is used to provide electricity and heat through fuel cell stacks as well as hydrogen fuel for fuel cell vehicles. In order to evaluate the environmental impacts related to the hydrogen production and utilisation, this work conducts an investigation of the entire life cycle of the described hydrogen production, transportation, and utilisation. All the processes related to the equipment manufacture, operation, maintenance, and disposal are considered in this study.

District heating markets are often dominated by monopolies in both Denmark and Finland. The same companies, often owned by local municipalities, are usually operating both supplying plants and district heating networks, while the pricing mechanisms are rigid, often agreed upon for one year in advance. The mentioned ownership scheme may cause problems, when one tries to gain a third party access in order to deliver excess heat or heat from cheaper heating plants. In this paper, two case studies were carried out to simulate the district heating systems based on dynamic pricing. Case studies were carried out for Sønderborg, Denmark and Espoo, Finland. The results showed that dynamic pricing fosters feeding the waste heat into the grid, as dynamic pricing reduced the total primary energy consumption and CO2 emissions in both case studies. In the best scenarios, the weighted average heat price decreased by 25.6% in Sønderborg and 6.6% in Espoo, respectively.

Efficiently utilizing energy that is currently being wasted can significantly increase energy efficiency of the system, as well as reduce the carbon footprint. In hot climates with large cooling demands, excess waste heat can be utilized via absorption chillers to generate cold. Moreover, cold from liquefied natural gas gasification process can further provide energy source for meeting the cold demand. In order to connect the large sources of waste heat and cold energy with customers demanding the cold, a significant investment in district cooling grid is a necessity. In order to deal with the mentioned issue, an existing energy balance model was complemented with Matlab algorithms in order to model the whole energy system, including the detailed representation of the district cooling grid. Singapore was chosen for a case study and several different scenarios were developed for the year 2050, with the main indicators being total primary energy supply, total CO2 emissions and total socio-economic costs. The most beneficial scenario for the year 2050 had 19.5% lower primary energy demand, 38.4% lower total socio-economic costs and 41.5% lower CO2 emissions compared to the business-as-usual scenario for the year 2050, although significant investment in the district cooling grid was included in the calculations.

In this paper, gate-fee changes of the waste-to-energy plants are investigated in the conditions set by European Union legislation and by the introduction of the new heat market. Waste management and sustainable energy supply are core issues of sustainable development of regions, especially urban areas. These two energy flows logically come together in the combined heat and power facility by waste incineration. However, the implementation of new legislation influences quantity and quality of municipal waste and operation of waste-to-energy systems. Once the legislation requirements are met, waste-to-energy plants need to be adapted to market operation. This influence is tracked by the gate-fee volatility. The operation of the waste-to-energy plant on electricity markets is simulated by using EnergyPLAN and heat market is simulated in Matlab, based on hourly marginal costs. The results have shown that the fuel switch reduced gate-fee and made the facility economically viable again. In the second case, the operation of the waste-to-energy plant on day-ahead electricity and heat market is analysed. It is shown that introducing heat market increased needed gate-fee on the yearly level over the expected levels. Therefore, it can be concluded that the proposed approach can make projects of otherwise questionable feasibility more attractive.

Municipal activities play an important role in national and global CO2-emission reduction efforts, with Nordic countries at the forefront thanks to their energy planning tradition and high penetration of renewable energy sources. In this work, we present a case study of the Danish municipality of Sonderborg, whose aim is to reach zero net CO2 emissions by 2029. Sonderborg has an official strategic plan towards 2029, which we compared with four alternative scenarios to investigate how the municipality could approach its target in the most energy-efficient and cost-effective way while simultaneously keeping biomass and waste consumption close to the limits of the locally available residual resources. We modelled all sectors of the energy system on the municipal scale, applying a broad range of energy conversion technologies, including advanced biomass conversion technologies and reversible electrolysis. We constructed five scenarios, each representing a different energy mix for Sonderborg’s energy system in 2029. We modelled these scenarios using the mixed-integer linear optimization tool Sifre. We compared the results for the five scenarios using four indicators: annual total system cost, total energy system efficiency, annual net system CO2 emissions and total annual biomass consumption. The results show that scenarios with a high degree of electrification perform better on the selected indicators than scenarios with a high degree of biomass utilization. Moreover, the incorporation of advanced conversion technologies such as electrolysis, fuel cells and methanol production further reduces both the total system cost and net CO2 of the highly electrified energy system. Our sensitivity analysis demonstrates that scenarios with a low biomass consumption and a high degree of electrification are less dependent on changes in energy prices. We conclude that in order to achieve their CO2 emission goals in the most energy-efficient, cost-effective and sustainable way, municipalities similar to Sonderborg should compare a wide range of energy system configurations, for example, scenarios with a high degree of electrification and a limited biomass use.

Although it can be complex to integrate variable renewable energy sources such as wind power and photovoltaics into an energy system, the potential benefits are large, as it can help reduce fuel imports, balance the trade, and mitigate the negative impacts in terms of climate change. In order to try to integrate a very large share of variable renewable energy sources into the energy system, an integrated energy planning approach was used, including ice storage in the cooling sector, a smart charging option in the transport sector, and an excess capacity of reverse osmosis technology that was utilised in order to provide flexibility to the energy system. A unit commitment and economic dispatch tool (PLEXOS) was used, and the model was run with both 5 min and 1 h time resolutions. The case study was carried out for a typical Caribbean island nation, based on data derived from measured data from Aruba. The results showed that 78.1% of the final electricity demand in 2020 was met by variable renewable energy sources, having 1.0% of curtailed energy in the energy system. The total economic cost of the modelled energy system was similar to the current energy system, dominated by the fossil fuel imports. The results are relevant for many populated islands and island nations.

The present work describes development of a High Temperature Thermal Energy Storage (HT-TES) system based on rock bed technology. A selection of rocks was investigated by thermal analysis in the range 20-800 ˚C. Subsequently, a shortlist was defined primarily based on mechanical and chemical stability upon thermal cycling. The most promising material consists of basalt, diabase, and magnetite, whereas the less suited rocks contain larger proportions of quartz and mica. An HT-TES system, containing 1.5 m3 of rock pieces, was constructed. The rock bed was heated to 600 ˚C using an electric heater to simulate thermal charging from wind energy. After complete heating of the rock bed it was left fully charged for hours to simulate actual storage conditions. Subsequently the bed discharging was performed by leading cold air through the rock bed whereby the air was heated and led to an exhaust. The results showed that HT-TES has a role to play in future, sustainable energy systems. A cost benefit analysis based on projected electricity prices for the Scandinavian region in 2035 showed that a business case is achievable.

The first joint EASE/EERA Technology Development Roadmap on energy storage1 was published in 2013 with the goal of identifying the most pressing technology development priorities for the European energy storage industry. Given the evolution and advancements in the energy storage sector - and, indeed, the energy sector as a whole - over the past several years, EASE and EERA have joined forces once more to draft a significant update to the 2013 roadmap. The roadmap is a joint effort between the European Association for Storage of Energy (EASE) and the Joint Programme on Energy Storage (JP ES) under the European Energy Research Alliance (EERA). Together, EASE and EERA members provide a strong foundation of industrial and research expertise, which allows for a deep and multifaceted insight into the European energy storage sector. This updated roadmap provides a comprehensive overview of the energy storage technologies being developed in Europe today, with a focus on stationary applications, and identifies the most pressing research, development and demonstration (RD&D) needs in the coming decades. Where applicable, energy storage for electro mobility is also considered in the technology sections. On this basis, the roadmap provides recommendations for research and development (R&D) policies and regulatory changes needed to support the development and large-scale deployment of energy storage technologies. The aim is to inform policymaking for research, innovation, and demonstration in the energy storage sector in order to further strengthen Europe's research and industrial competitiveness. More information about the methodology used to elaborate this roadmap is contained in Chapter 2. Chapter 3 lists the mission and objectives. Chapter 4 explains the European and global policy developments affecting the energy system in Europe and the role foreseen for energy storage. Chapter 5 describes the future needs for energy storage and, explains the key applications for the electrical system and for sector interfaces. This Chapter also provides an overview of the energy storage technologies, and outlines the European competences in energy storage. EASE and EERA consider that a wide range of energy storage technologies will be needed to address the challenges of the energy transition. Chapter 6, the bulk of this roadmap, therefore covers the five families of energy storage technologies in detail: chemical energy storage, electrochemical energy storage, electrical energy storage (including both supercapacitors and superconducting magnetic energy storage), mechanical energy storage (covering compressed air energy storage, flywheels, liquid air energy storage, and pumped hydro storage), and thermal energy storage (broken down into sensible heat storage, latent heat storage, and thermochemical heat storage). For each of these technologies, there is a description of their technical maturity, applications, R&D targets, an identification of gaps between the present status and these targets, a list of research priorities, and recommendations for research funding, infrastructures, and incentives.

A linear continuous optimization model with an hourly time resolution was developed in order to model the impact of subsequent interconnections of different DH grids. The municipality of Sønderborg was chosen for a case study and interconnections of five currently disconnected DH grids were assessed. Moreover, the impact of industrial waste heat on the DH supply was also assessed. In the reference year (2013) two out of four interconnections proved to be economically viable. The results for the future energy system (2029) showed that interconnecting geographically distributed DH grids reduces primary energy supply by 9.5%, CO2 emissions by 11.1% and total system costs by 6.3%. Inclusion of industrial waste heat in the fully interconnected DH grid reduced primary energy supply for an additional 3%, CO2 emissions for an additional 2.2% and total system costs for an additional 1.3%. The case of the future energy supply system with interconnected DH grids and installed industrial waste heat recuperation results in the lowest primary energy demand, emissions and costs. Finally, the benefits of the interconnected DH grid, in terms of system flexibility, CO2 emissions, total costs and energy efficiency, proved to be much greater in the future energy system.

Alloy having the composition of Mg-72 mass%–Ni-20 mass%–La-8 mass% prepared by vacuum-induction melting was studied by means of optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction analysis. Metallographic investigations evidence that the alloy has a fine and uniform grain structure which corresponds to the structure of a ternary eutectic alloy. The surface of a metallographic cross section of the alloy was subjected to hydrogenation in various conditions and studied by means of the mentioned methods. It is shown that during the initial stage of hydrogenation the phase La 2 Mg 17 is decomposed at first. Then the phase LaH 3 is formed, while the formation of the MgH 2 phase proceeds at a slowest rate. This hydrogenation behaviour is explained by taking into account the microstructure peculiarities of the alloy.

The interaction of hydrogen with an Mg–Al alloy pre-exposed to air have been studied with in situ time resolved X-ray powder diffraction. Phase fractions as a function of time are derived from series of consecutive diffraction patterns allowing kinetic analysis. The apparent activation energy for dehydrogenation of the Mg–Al alloy is found to be 160 kJ/mol. This is not significantly higher than for pure and fully activated Mg. It is suggested that the addition of Al improves the resistance towards oxygen contamination.

In this paper, we investigate the dehydrogenation kinetics of LiAlH 4 into Li 3 AlH 6 (reaction I) and further into LiH (reaction II). We find the apparent activation energies to be ∼ 80 and 100 kJ/mol for reactions I and II, respectively. Furthermore, we investigate the effect of ball milling on crystallite size and the dehydrogenation kinetics of both reactions I and II. We find a clear correlation between crystallite size and dehydrogenation kinetics of reaction I. On the other hand, we find the kinetics of reaction II to be independent of the crystallite size. This indicates that reaction I is limited by a mass transfer process, while reaction II is limited by the intrinsic kinetics.

The dehydrogenation kinetics of air exposed samples of MgH2/Mg2Cu and MgH2/MgCu2 have been studied with in situ time resolved X-ray powder diffraction. The X-ray setup enabled the recording of full diffraction patterns within 150 s, thereby allowing the study of structural changes combined with simultaneous extraction of kinetic parameters. Phase fractions as a function of time and temperature were derived from series of consecutive diffraction patterns by numerical integration of selected diffraction peaks. The apparent activation energy for the dehydrogenation of the MgH2/Mg2Cu, and MgH2/MgCu2 sample was found to be 108 kJ/mol and 160 kJ/mol, respectively. Furthermore, substantially improved dehydrogenation kinetics of MgH2 and resistance towards oxidation of Mg due to the presence of Mg2Cu/MgCu2 are discussed in relation to previous work.

The main objective of the work was to investigate the effect of addition of ceramic particles with different size distributions on the mechanical properties, e.g. wear resistance and tensile strength, of spray formed materials. The experiments were carried out in a spray-forming unit at Riso National Laboratory, Denmark, where composites with a low alloyed boron steel (0.2 wt.% carbon) matrix containing alumina particles were produced. A comparison between cast hot-rolled material without particles, spray formed material without particles and the spray formed composites with an average ceramic particle size of 46 and 134 μm were carried out with respect to their mechanical properties e.g. wear resistance and tensile strength. It was found that the addition of Al2O3 particles to the steel improves its wear properties and reduces the elongation and tensile strength of the material, but the material still showed good ductility. The composite material was also forged and showed good forgeability.

Amorphous (Mg1−yAly)60Cu30Y10 alloys (with y between 0 and 7 at.%) have been prepared by casting the melt into a Cu mold. Differential scanning calorimetry is used to determine the crystallisation and the glass transition temperatures as functions of sample composition and heating rates. The supercooled liquid region (ΔT=Tx−Tg) is found to become smaller with substitution of Mg with Al. The glass forming ability is also found to decrease with the addition of Al. The dependence of the crystallisation and glass transition temperatures are fitted to a Kissinger or a Vogel–Fulcher–Tammann type of expression. Combined with the cooling history of the samples the critical cooling rate is deduced to be 70±20 K s −1 .

Bulk amorphous (Mg 1-y Al y ) 60 Cu 30 Y 10 alloys were prepared using a relatively simple technique of rapid cooling of the melt in a copper wedge mould. The temperature vs. time was recorded during the cooling and solidilication process of the melt and compared with a spacial and temporal numerical simulation of that process. It is concluded that good thermal contact is maintained between the amorphous part of the solidified sample and the mould, while a rather poor contact develops between the crystalline part of the sample and the mould, probably due to the appearance of a narrow gap at the crystal-mould interface during crystallisation. The maximum amorphous layer thickness decreases from ∼3 mm to zero when the Al content increases in the range from 0 to about y = 10%. The evolution of the microstructure of the initially amorphous phase was examined by x-ray diffraction (XRD) and differential scanning calorimetry (DSC) for different alloy compositions and annealing temperatures. On annealing into the supercooled liquid state (441 K), specimens with no Al content remain basically amorphous while nanoparticles are formed and remain stable also at higher temperatures in specimens containing a few percent Al. The alloy with no Al crystallises apparently without the formation of nanoparticles. The critical cooling rate for the formation of an amorphous Mg 60 Cu 30 Y 10 specimen was determined experimentally by a combination of DSC data and temperature vs. time measurements to be 60-150 K/s, in agreement with estimates from the literature. The Vickers hardness (H V ) of the amorphous material for y = 2% is higher (∼360 kg/mm 2 ) than for y = 0 (∼290 kg/mm 2 ). On crystallisation the hardness of the latter material increases to the 400 kg/mm 2 level while the hardness of the former does not change.

Recently, Inoue and Masumoto have found that Mg-Cu-Y alloys show high glass-forming ability (GFA), hence making it possible to produce bulk amorphous samples of such alloys. The aim of the present work was to characterize in some detail one of these new bulk amorphous alloys, (Mg{sub 0.98}Al{sub 0.02}){sub 60}Cu{sub 30}Y{sub 10}. Its stability and crystallization process was examined by using x-ray diffraction (XRD), differential scanning calorimetry (DSC) and small-angle neutron scattering (SANS). One finding was the formation of nanocrystalline particles on annealing. It was also found that the addition of Al increases the hardness.

Rapidly solidified martensitic stainless steel (11.59Cr-0.98Mo-0.28V (in wt pct) ribbons have been produced by the melt-spinning process. The microstructure of the ribbons showed three distinct zones: a columnar, a cellular, and a cellular-dendritic zone. The height of the columnar grain zone is independent of the process parameters such as the wheel material or the wheel velocity. Due to a high level of undercooling and a high growth velocity of the solid/liquid interface, the rapid solidification process is found to suppress the formation of δ-ferrite and enhance the formation of austenite. The austenite is transformed into martensite upon cooling. In comparison with conventional solidification, a reduction in the initial austenite grain size has been found to result in a very fine lath martensite (M) structure. Investigations of the texture within the ribbons along the growth direction show a weak fiber texture. Transmission electron microscopy (TEM) has revealed a [111]M1 ‖ [001]M2 and (011)M1 ‖ (110)M2 orientation relationship between two neighboring martensite laths. The observed orientation relationship is a result of a superposition of both the Kurdjumov-Sachs (K-S) and Nishiyama-Wasserman (N-W) orientation relations.

The global megatrend of the last century’s migration from rural to ever-larger conurbations has created immense gains to society through economies of scale and benefits from agglomeration. These include – other things remaining equal – a lesser need for transport because a bigger share of peoples’ activities can be reached within the relative close distances of the city. However, urbanisation has also led to significant disadvantages, of which transport accounts for some of the most severe. Traffic accidents and emissions of air pollutants and noise take heavy tolls in terms of people killed and injured, although in many countries the situation has improved over recent decades. Two major issues, however, have proven very difficult to cope with, to the point where the problems they cause are not yet diminishing.

The possible existence of a compensation effect, i.e. concurrent changes in activation energy and prefactor, is investigated for the hydrogenation and dehydrogenation kinetics of metal hydrides, by analyzing a series of reported kinetic studies on Mg and LaNi(5) based hydrides. For these systems, we find a clear linear relation between apparent prefactors and apparent activation energies, as obtained from an Arrhenius analysis, indicating the existence of a compensation effect. Large changes in apparent activation energies in the case of Mg based hydrides are rationalized in terms of a dependency of observed apparent activation energy on the degree of surface oxidation, i.e., a physical effect. On the other hand, we find the large concurrent changes in apparent prefactors to be a direct result of the Arrhenius analysis. Thus, we find the observed compensation effect to be an artifact of the data analysis rather than a physical phenomenon. In the case of LaNi(5) based hydrides, observed scatter in reported apparent activation energies is less pronounced supporting the general experience that LaNi(5) is less sensitive toward surface contamination.

The dehydrogenation kinetics of pure and nickel (Ni)-doped (2 w/w%) magnesium hydride ( MgH 2 ) have been investigated by in situ time-resolved powder X-ray diffraction (PXD). Deactivated samples, i.e. air exposed, are investigated in order to focus on the effect of magnesium oxide (MgO) surface layers, which might be unavoidable for magnesium (Mg)-based storage media for mobile applications. A curved position-sensitive detector covering 120 ∘ in 2 θ and a rotating anode X-ray source provide a time resolution of 45 s and up to 90 powder patterns collected during an experiment under isothermal conditions. A quartz capillary cell allowed the in situ study of gas/solid reactions. Three phases were identified: Mg, MgH 2 and MgO and their phase fractions were extracted by Rietveld refinement or integration of selected reflections from each phase. Dehydrogenation curves were constructed and analysed by the Johnson–Mehl–Avrami formalism in order to derive rate constants at different temperatures. The apparent activation energies for dehydrogenation of pure and Ni-doped magnesium hydride were E A ≈ 300 and 250 kJ / mol , respectively. Differential scanning calorimetry gave, E A = 270 kJ / mol for dehydrogenation of the Ni-doped sample. The relatively high activation energies are due to MgO surface layers, retarding the diffusion of hydrogen ( H 2 ) out of MgH 2 / Mg . The observed difference in E A of ca. 50 kJ/mol is likely due to the catalytic effect of Ni on the recombination of H atoms to H 2 molecules verified by theoretical considerations.

Bulk Mg-Cu-Y-Al alloys, prepared by casting into a wedge-shaped copper mold, have been studied in the as-prepared, the supercooled liquid, and the crystalline states. In the as-prepared state x-ray diffraction of sub-millimeter sized regions were performed using a focused x-ray beam. The phase composition of the cross section as well as of the surface of the wedge-shaped specimen was investigated as a function of position. The cooling history of the alloy was experimentally determined and compared to results of a control-volume finite-difference modelling study. The experimentally determined and the calculated cooling rates were correlated with the observed amorphous/crystalline structure. The transition from an amorphous to a crystalline state was followed by x-ray diffraction studies as a function of time at specific temperatures in the region between the glass transition and the crystallization temperature. Based on these results a temperature-time-phase diagram was constructed. The dependence of external pressure on the crystallisation temperature was investigated by in situ high-temperature and high- pressure x-ray powder diffraction by using synchrotron radiation. The investigations form the basis for a selection of the optimum temperature in the supercooled liquid region for performing deformation/shaping of the Mg-based alloys.

The crystal structures of YbD 2 and YbH 2 have been studied by elastic neutron scattering on powdered samples at room temperature and atmospheric pressure. The neutron diffraction data have been analysed by means of the EDINP profile structure refinement program. The analyses confirmed the assumption that both compounds are isostructural with the hydrides of the alkaline-earth metals at room temperature and atmospheric pressure. All atoms are found to occupy the 4(c) position in the orthorhombic space group D~ 6 (Prima). The atomic positions were found to be: x(Yb)=0.243, z(Yb)=0.111; x(D') = 0.358, z(D') = 0-433; and'x(D") = -0.021, z(D") = 0.675. By inference from these atomic positions, it is suggested that the room-temperature high-pressure (p > 15 GPa) hexagonal structure of YbH 2 is D4h (P63/mmc) with the metal atoms in 2(c) positions and the hydrogen atoms in 2(a) and 2(d) positions.

A study of the hydrogenation characteristics of fine magnesium powder during repeated cycling has been performed using a high-pressure microbalance facility. No effect was found from the cycling regarding kinetics and storage capacity. The reaction rate of the absorption process was fast at temperatures around 600 K and above, but the reversed reaction showed somewhat slower kinetics around 600 K. At higher temperatures the opposite was found. The enthalpy and entropy change by the hydrogenation, derived from pressure-concentration isotherms, agree fairly well with those reported earlier.

Two identical samples of magnesium powder (purity, 99.58%) were hydrogenated at approximately 30 bar and 380 °C and dehydrogenated under vacuum at the same temperature about 500 times. The first sample was exposed to pure hydrogen (purity, 99.9999%) and the second was exposed to hydrogen containing 85 ppm O and 8 ppm H 2 O vapour. In both experiments a moderate overall reduction in the amount of hydrogen absorbed and desorbed was observed. This can be ascribed to a reduced absorption rate with increased number of cycles. The effect of oxygen was negligible, and this was confirmed by a precision absorption measurement performed after the cycling experiment. Despite the decreased absorption rate, which was mainly observed at higher degrees of reaction, little change in the desorption kinetics was observed.

In a series of continuous cycling experiments magnesium powder with average particle diameter around 65 μm was exposed to hydrogen gases containing oxygen and nitrogen. The absorption and the desorption were measured over approx 17 min each at a temperature of 375°C with small variations caused by the heat of reaction. The hydrogen gases used were N57 (99.9997%), H2 + approx. 0.5% O2 and H2 + approx. 0.5% N2. In pure hydrogen approx. 95% of the magnesium reacted within the absorption period to form MgH2. When 0.5% O2 or N2 was added a prompt drop took place. When the Mg powder was exposed to 0.5% N2 from the start, the uptake of hydrogen gradually rose to 35% over 50 cycles. The sample exposed to 0.5% O2 suffered a permanent loss of approximately 20% of the initial capacity. The effect of 0.5% N2 was similar but less pronounced. The temporary and permanent effects of the impurities are discussed.

The surface reaction of hydrogen (and of deuterium) with activated FeTi was studied by UHV volumetric vapour pressure measurements in the 3 × 10-8 Pa to 1.3 × 10-5 Pa range at 78 K and 88 K. At the low temperatures a dissociative non-activated Temkin chemisorption process was found. An isosteric heat of adsorption, q, was described by the expression q = 24(1 - θ) kJ/(mole H2) for a broad range of coverages. It was demonstrated that the dissociation occurred on a non-oxidized Ti-surface and not - as has been suggested - on a segregated subsurface Fe-layer.

Magnesium powder with a grain size of approximately 50γm was hydrogenated for 30 min and dehydrogenated the same time at 390°C, 515 times. A moderate loss in hydrogen storage capacity was observed and was ascribed to a measured decrease in reaction kinetics as the cycle number increased. The time for maximum hydrogen absorption was found to depend significantly on cycle number while the time for maximum desorption was found to be virtually independent of cycle number.

The bulk amorphous alloy (Mg1-xAlx)60Cu30Y10 has been studied, in particular the influence of Al concentration on the glass forming ability and on the various transition temperatures. The amorphous single phase has been obtained for x up to 0.07 by casting into a wedge-shaped copper mold. The amorphous alloys were investigated by differential scannning calorimetry (DSC). All the specimens with x = 0 - 0.07 show a clear glass transition. The crystallization temperature decreases with increasing Al concentration, while the temperatures of the glass transition, melting and solidification change only slightly. The DSC measurements show that for Al contents below 0.05 the first exothermic peak which corresponds to crystallization, consists of two overlapping peaks. To clarify the origin of the splitting of the first exothermic peak, the crystallization process of Mg60Cu30Y10 alloy has also been studied by x-ray diffraction.

The initial reaction of hydrogen and deuterium with clean surfaces of FeTi powder, following a five-cycles activation procedure using hydrogen, were studied by volumetric and microgravimetric techniques. – It was concluded that within the 78 K to 88 K temperature range a non-activated dissociative Temkin chemisorption process occurred upon a Ti surface layer, while at temperatures within the 300 K to 500 K range a dissolution process took place limited by diffusion in the α-phase.