LIQHYSMES storage unit – Hybrid energy storage concept combining liquefied hydrogen with Superconducting Magnetic Energy Storage

A new energy storage concept for variable renewable energy, LIQHYSMES, has been proposed which combines the use of LIQuid HYdrogen (LH2) with Superconducting Magnetic Energy Storage (SMES). LH2 with its high volumetric energy density and, compared with compressed hydrogen, increased operational safety is a prime energy carrier for large scale stationary energy storage. But balancing load or supply fluctuations from seconds to several hours with hydrogen alone is difficult due to the response times of the flow control, and an additional short-term electrical energy storage will be needed. For this purpose a compact LIQHYSMES Storage Unit is proposed which integrates the H2 liquefaction part, the LH2 tank and the SMES based on Magnesium Diboride and cooled by the LH2 bath. This allows jointly utilizing the cryogenic infrastructure and reducing the otherwise significant H2 liquefaction losses by introducing a novel process with “cold recovery”. Preliminary target numbers for this process, key parameters for a complete LIQHYSMES model plant, simulations on the anticipated buffering behaviour, a loss analysis and a crude cost estimate are given.     

Sustainability and property valuation: a risk-based approach

The proportion of sustainable property in the total building stock remains small. One reason is that the financial added value resulting from sustainability is not sufficiently taken into account in property valuation due to the tendency of valuations to lag behind market trends. Quantitative information is provided to integrate those aspects of sustainability relating to value into valuations and thereby contribute to the reduction of valuation lag. The Centre for Corporate Responsibility and Sustainability (CCRS) Economic Sustainability Indicator (ESI) measures the risk of property to lose value and the opportunity to gain value due to future developments (e.g. climate change or rising energy prices). Five groups of value-related sustainability features were identified: flexibility and polyvalence; energy and water dependency; accessibility and mobility; security; and health and comfort. By minimizing the risk of loss in value through future developments, those sustainability features contribute to the property value. Their effects on property value were quantified by risk modelling. As an indicator for future-oriented property risk, the ESI is integrated into the discount rate of discounted cash flow valuations. The approach was tested for plausibility and practicability on more than 200 properties.

La proportion de biens immobiliers durables dans le parc immobilier total demeure faible. L'explication tient pour une part au fait que la valeur ajoutée financière résultant de la durabilité n'est pas suffisamment prise en compte dans l'évaluation des biens immobiliers en raison du fait que les évaluations tendent à avoir du retard sur les tendances du marché. Des informations quantitatives sont fournies afin d'intégrer les aspects de la durabilité liés à la valeur dans les évaluations et de contribuer ainsi à la réduction du retard dans les évaluations. L'Indicateur de Durabilité Economique (ESI) du Centre pour la Responsabilité et la Durabilité en Entreprise (CCRS) mesure le risque de perte de valeur des biens immobiliers et la possibilité d'en accroître la valeur du fait des évolutions futures (par ex. changement climatique et hausse des prix énergétiques). Cinq groupes de fonctions de durabilité liées à la valeur ont été identifiés: flexibilité et polyvalence, dépendance vis-à-vis de l'énergie et de l'eau; accessibilité et mobilité; sécurité; santé et confort. En minimisant le risque d'une perte de valeur causée par les évolutions futures, ces fonctions de durabilité contribuent à la valeur des biens immobiliers. Leurs effets sur la valeur des biens immobiliers ont été quantifiés par une modélisation des risques. En tant qu'indicateur du risque prospectif pour les biens immobiliers, l'ESI est intégré au taux d'actualisation des flux de trésorerie actualisés. Cette approche a été testée quant à sa plausibilité et sa praticabilité sur plus de 200 biens immobiliers.

Mots clés: flux de trésorerie actualisés, indicateur de durabilité économique, évaluation des biens immobiliers, modèle de risque, fonctions de durabilité, durabilité, bâtiments durables     

Frequency of correctness versus average polynomial time

We prove that every distributional problem solvable in polynomial time on the average with respect to the uniform distribution has a frequently self-knowingly correct polynomial-time algorithm.     

Bulk Sediment and Diatom Silica Carbon Isotope Composition from Coastal Marine Sediments off East Antarctica

Organic carbon occluded in diatom silica is assumed to be protected from degradation in the sediment. δ¹³C from diatom carbon (δ¹³C_(diatom)) therefore potentially provides a signal of conditions during diatom growth. However, there have been few studies based on δ¹³C_(diatom). Numerous variables can influence δ¹³C of organic matter in the marine environment (e.g., salinity, light, nutrient and CO₂ availability). Here we compare δ¹³C_(diatom) and δ¹³C_(TOC) from three sediment records from individual marine inlets (Rauer Group, East Antarctica) to (i) investigate deviations between δ¹³C_(diatom) and δ¹³C_(TOC), to (ii) identify biological and environmental controls on δ¹³C_(diatom) and δ¹³C_(TOC), and to (iii) discuss δ¹³C_(diatom) as a proxy for environmental and climate reconstructions. The records show individual δ¹³C_(diatom) and δ¹³C_(TOC) characteristics, which indicates that δ¹³C is not primarily controlled by regional climate or atmospheric CO₂ concentration. Since the inlets vary in water depths offsets in δ¹³C are probably related to differences in water column stratification and mixing, which influences redistribution of nutrients and carbon within each inlet. In our dataset changes in δ¹³C_(diatom) and δ¹³C_(TOC) could not unequivocally be ascribed to changes in diatom species composition, either because the variation in δ¹³C_(diatom) between the observed species is too small or because other environmental controls are more dominant. Records from the Southern Ocean show depleted δ¹³C_(diatom) values (1–4 ‰) during glacial times compared to the Holocene. Although climate variability throughout the Holocene is low compared to glacial/interglacial variability, we find variability in δ¹³C_(diatom), which is in the same order of magnitude. δ¹³C of organic matter produced in the costal marine environment seems to be much more sensitive to environmental changes than open ocean sites and δ¹³C is of strongly local nature.     

Large scale production of indium antimonide film for position sensors in automobile engines

We use low pressure MOVPE to grow indium antimonide films on groups of eight 3 inch GaAs wafers per run. The films are used for the production of magnetoresistive position sensors for the car industry. To meet the narrow specifications for automotive components, the standard deviation of the sheet resistivity, and the thickness of the films have been reduced below 1.5%. This uniformity is the result of an optimization process encompassing the determination of the best susceptor temperature and the optimum flow. The gas velocity was found to have a large impact on the uniformity of the layers. Rotation of the wafers and the use of an optimum gas velocity results in extremely uniform layers.     

Gezielte Manipulation von Mikropartikeln in einem Plasma. Manipulation of micro‐disperse particles in a process plasma

An optimal treatment (surface modification, coating) of micro‐disperse materials (powder, granulate, fibres etc.) by a process plasma requires the understanding of plasma‐particle interaction. For this purpose, related experimental investigations in a novel set‐up PULVA‐INP will be presented.     

The generalized Lévêque equation and its practical use for the prediction of heat and mass transfer rates from pressure drop

Based on the generalized Lévêque equation (GLE) a new type of analogy between pressure drop and heat transfer has been discovered, that may be used in the cross corrugated channels of chevron type plate heat exchangers, in packed beds, in tube bundles, in crossed rod matrices or in many other spacewise periodic arrangements.Experimental data on heat transfer in tube bundles in crossflow, both inline, and staggered arrangements, had been recently tested in greater detail. Using an empirical correlation for pressure drop in these arrangements from the literature that has been successfully tested against a large number of experimental pressure drop data, heat transfer data collected earlier could be very well represented from the pressure drop correlation and the GLE. The data for staggered bundles have been shown to be in better agreement with this new method, than with the existing empirical heat and mass transfer correlations. Somewhat larger deviations for inline tube bundles had been found at lower Reynolds numbers. Here a simple and physically reasonable correction function of Re is presented, which leads to a better agreement for the inline bundles, too.Additionally, it can be shown for a number of literature data on tube bundles and on crossed rod matrices that the agreement with the GLE prediction is even better if original pressure drop data from the same sources are available in place of a pressure drop correlation.The method results in reasonable heat or mass transfer predictions from frictional pressure drop, which may be widely used in chemical engineering applications.