Einsatz der Brennstoffzelle als Netzersatzanlage sicherheitsrelevanter Digitalfunkstationen im Feldtest

Es wird anhand des Förderprojekts „Wasserstoff-Netzersatzanlagen der Behörden und Organisationen mit Sicherheitsaufgaben (BOS) des Landes Brandenburg“ des Zentraldienstes der Polizei des Landes Brandenburg die Praxistauglichkeit von Brennstoffzellen-Netzersatzanlagen untersucht. Marktreife und kommerziell verfügbare Brennstoffzellen wurden in 115 sicherheitsrelevanten Digitalfunkstationen im Flächenland Brandenburg als Ersatz von wartungsintensiven und umweltproblematischen Dieselgeneratoren für die (Not-)Stromversorgung installiert. Diese Netzersatzanlagen sind für eine Überbrückungszeit von 72 h unter realen Bedingungen ausgelegt und wurden im Feldtest, parallel zum realen Betrieb, über einen längeren Einsatzzeitraum (ca. 2 Jahre) auf ihre Zuverlässigkeit und Verfügbarkeit hin untersucht. Die Anforderungen an und die Realisierung der Brennstoffzellen-Netzersatzanlagen sowie die Feldtest-Versuchsplanung und deren Ergebnisse werden beschrieben und diskutiert. Die Praxistauglichkeit wird mit einer hohen Verfügbarkeit über 97 % und einer Funktionszuverlässigkeit von mehr als 95 % erfolgreich bestätigt. Die Entwicklung weiterer Komponenten wird empfohlen.On the basis of the funding project "Hydrogen Based Backup Power Systems of Public Authorities and Organizations with Security Tasks (BOS) of the German Federal State of Brandenburg" of the Central Police’s Services of the German Federal State of Brandenburg, the practicability of fuel-cell backup power systems is investigated. Within this project, market-ready and commercially available fuel-cell systems were installed in 115 security-relevant digital telecommunication units in the Federal State of Brandenburg as a replacement for maintenance-intensive and environmentally-hazardous diesel generators for (emergency) power supply. These emergency power systems are designed for a bridging time of 72 hours under real conditions and have been tested for their reliability and availability over a longer period of operation (approx. 2 years) in the field test, simultaneously with real operation. The requirements and realization of the fuel cell backup power systems as well as the field test planning and their results are described and discussed. The practicability is successfully confirmed with a high availability of more than 97 % and a functional reliability of more than 95 %. Additional development requirements for further components are recommended

Minimizing conservativity violations in ontology alignments: algorithms and evaluation

In order to enable interoperability between ontology-based systems, ontology matching techniques have been proposed. However, when the generated mappings lead to undesired logical consequences, their usefulness may be diminished. In this paper, we present an approach to detect and minimize the violations of the so-called conservativity principle where novel subsumption entailments between named concepts in one of the input ontologies are considered as unwanted. The practical applicability of the proposed approach is experimentally demonstrated on the datasets from the Ontology Alignment Evaluation Initiative

False discovery rate estimation and heterobifunctional cross-linkers

<div><p>False discovery rate (FDR) estimation is a cornerstone of proteomics that has recently been adapted to cross-linking/mass spectrometry. Here we demonstrate that heterobifunctional cross-linkers, while theoretically different from homobifunctional cross-linkers, need not be considered separately in practice. We develop and then evaluate the impact of applying a correct FDR formula for use of heterobifunctional cross-linkers and conclude that there are minimal practical advantages. Hence a single formula can be applied to data generated from the many different non-cleavable cross-linkers.</p></div

Turnaround in Energy Policy – Measures to Reduce the Carbon Dioxide Emission from the Private Sector

The greenhouse gases (GHG) carbon dioxide (CO 2 ), methane (CH 4 ) and nitrous oxide (N 2 O) are considered mainly to be responsible for the additional anthropogenic greenhouse effect, the so-called “global warming”. In the private sector, the “Rational Use of Energy” can be a very effective tool (i) to reduce the greenhouse gas emissions, (ii) to decrease the annual energy costs and furthermore (iii) it prepares the integration of Renewable Energy Sources by saving conventional, mostly fossil energy. Aim of this paper is (i) to show that by applying energy saving measures, the primary energy demand and thus the individual (direct) carbon dioxide emission can be reduced in a relevant scale. (ii) It is to give laterally information about (ii.i) the energy market structure and (ii.ii) the legal backgrounds in the EU

Sustainably Produced Hydrogen

The fossil fuels used to provide energy, such as coal, crude oil and natural gas, are largely responsible for carbon dioxide emissions and other so-called greenhouse gases. Hydrogen gas (H2) can make a key contribution to decarbonization. It can be produced using various processes. Several processes are available to produce hydrogen, such as (i) steam reforming, (ii) cracking process or (iii) electrolysis. Depending on the source of origin, there is a distinction made between different “colours”. Gray, blue, turquoise, yellow and green hydrogen is avail­able, the latter made using Renewable Energies. However, items such as (i) possible variants of hydrogen, (ii) leading export countries or (iii) provision paths to be preferred in the future will be discussed in this paper

A Short Approximation Method to Pre-estimate the Electric Yield of Wind Farms

Amongst the Renewable Energy Sources (RES) contributing to the worldwide electricity production, wind energy became very important. Germany and several other countries own significant wind potentials. 2% of a country’s area can be used for wind farms, thus Germany could produce easily up to 200 TWhel yearly just onshore. However, often legal and especially financial aspects decide about the speed of development. Careful project preparation guaranteed by professional management is obligatory. Beside factors such as (i) rights to the property and (ii) electric grid connection, (iii) the sufficiency of the wind and peripheral conditions need to be known. A proper wind forecast and yield prognoses are important items. To solve these tasks, professional programs are sold on the markets. To offer a convenient alternative, authors will present software based on Excel named as WindCalc 1.5, which is still under development

Bi-facial Open-Space Photovoltaic Systems versus Conventional Systems using Mono-facial Modules

As part of a scientific work within the solar company Sunfarming GmbH, the aim was to find out whether bi-facial modules on open spaces deliver better results economically than conventional mono-facial solar modules. In this context, an already installed 750 kWp PV system with mono-facial solar modules was compared directly with a structurally identical PV system with bi-facial modules, which, however, does not exist in practice but was only simulated with PV software. The second part of the investigation includes the comparison of four different assembly systems or elevation variants in order to determine the system with the best relationship between system yield and costs. The final result of the first investigation showed that the use of bi-facial modules reduced the specific costs per kWh by approximately 5 %. In order to improve this effect, the use of compact assembly systems is recommended, e.g. five rows of modules per table with horizontal alignment

Primary Energy Balance and Energy Pay-back Time after Insulating an Outer Wall – Comparing Northern Europeand the Eastern Mediterranean Region

Taking for buildings a specific annual heat demand of 70 kWh/(m2*a) for heating plus 12.5 kWh/(m2*a) for hot water into account, by the measures of “Rational Use of Energy” the German fi nal energy demand in the private sector could be reduced by 300 TWh annually (same as up to hundred Mtons of CO2) (a = year). This paper will summarize some data for Germany compared to Turkey and evaluate the ecological feasibility of a 10 cm thick rockwool insulation of an outer building wall. The energy pay-back time for the locations Potsdam/Germany and Izmir/Turkey will be calculated and interpreted. Furthermore, this paper is to propagate energy conservation as an important tool (i) to save primary energy consumption, in order (ii) to reduce the import of fossil fuels and thus to strengthen the domestic economy, and (iii) to reduce the emission of the greenhouse gas CO2 and thus to decrease the climatic effect

Hydrogen and Usability of Hydrogen Storage Technologies

Science, technology and politics agree: hydrogen will be the energy carrier of the future. It will replace fossil fuels based on a sufficient supply from sustainable energy. Since the possibilities of storing and transporting hydrogen play a decisive role here, the so-called LOHC (Liquid Organic Hydrogen Carriers) can be used as carrier materials. LOHC carrier materials can reversibly absorb hydrogen, store it without loss and release it again when needed. Since little or no pressure is required, normal containers or tanks can be used. The volume or mass-related energy densities can reach around a quarter of liquid fossil fuels. This paper is to give an introduction to the field of hydrogen storage and usage of those LOHC, in particular. The developments of the last ten years have been related to the storage and transport of hydrogen with LOHC. These are crucial to meet the future demand for energy carriers e.g. for mobile applications. For this purpose, all transport systems are under consideration as well as the decentralized supply of rural areas with low technological penetration, e.g. regions of Western Africa which are often characterized by a lack of energy supply. Hydrogen bound in LOHC can provide a hazard-free alternative for distribution. The paper provides an overview of the conversion forms as well as the chemical carrier materials. Dibenzyltoluene as well as N-ethylcarbazole - as examples for LOHC - are discussed as well as chemical hydrogen storage materials like ammonia boranes as alternatives to LOHC

Beschreibung eines regenerativen Energiesystems mit Wasserstoff- und Brennstoffzellentechnik für Lehre und angewandte Forschung

Angesichts der begrenzten Reichweiten fossiler Ressourcen und der durch ihren Verbrauch entstehenden Umweltprobleme, sind regenerative Energien notwendig für eine klimafreundliche Sicherstellung der Energieversorgung der Erde. Ein Hindernis für die breite Einführung regenerativer Energien ist, dass diese nicht grundlastfähig sind. Neue Speichertechnologien und komplexes Energiemanagement können hier Abhilfe schaffen. Die in dieser Veröffentlichung vorgestellte Anlage leistet hierzu einen Beitrag, insbesondere in der Ausbildung benötigter Ingenieure und Wirtschaftler. Kernkomponente dieser Anlage stellt die Wasserstoff- und Brennstoffzellentechnik zur klimafreundlichen Erzeugung, Speicherung und Rückverstromung von Wasserstoff dar. Mittels regenerativer Energien wird mit einem Elektrolyseur Wasserstoff erzeugt. Die Speicherung erfolgt in Metallhydridspeichern, welche sehr gut an das Druckniveau des Elektrolyseurs angepasst sind. Die Rückverstromung erfolgt mittels Brennstoffzellen. Es wird auf die praxisnahen Experimentiermöglichkeiten dieser Anlage, die ersten Betriebserfahrungen und auf zukünftige Forschungsthemen, eingegangen