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  • 1.
    Ahmed, Hatem
    et al.
    Jönköping University, Jönköping International Business School.
    Lanouar, Zineb
    Jönköping University, Jönköping International Business School.
    Barriers and Motivations to Energy Efficiency Technology Implementations: A Case Study in a Swedish Foundry Industry2021Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In the pursuit of responding to climate change and reducing Greenhouse Gases (GHG) emissions caused by human activities, restrictions and regulations took place by international policymakers to limit the harmful effect on the environment. Thus, Energy-intensive industries are experiencing an unprecedented challenge due to more strict rules and limitations by governments in the EU and Sweden on unsustainable practices. 

    The purpose of the study is to highlight the barriers and benefits of investing in Energy Efficiency Technologies (EETs) such as Waste Heat Recovery (WHR) and Electric Energy Storage Systems (EESS) in a Swedish foundry firm. Further conduct a feasibility study of the selected technologies in the foundry energy system to understand to which extent improvements in Energy Efficiency (EE), cost reduction and GHG emissions take place. Further, contribute to the literature of Energy Management (EnM) by presenting a framework for decision-makers in energy-intensive industries to enable the implementation of EETs. 

    A single case study took place to generate and relate important theories in managerial practices. Semi-structured and structured interviews were conducted with experts involved in the foundry industry, EETs, and energy consultants. Moreover, documents were also provided to extract data. The qualitative data analysis was conducted using the framework analysis method while the quantitative analysis was performed using modeling through RETScreen software. 

    The results indicate that the main barriers to EETs are financial aspects, while environmental aspects were perceived as the most significant benefits. Furthermore, the feasibility study conducted proved a reduction of 4% in energy consumption, a reduction of 3% in annual GHG emissions, and a payback period of 5 years which was unfavorable for the investigated foundry. Further, the authors recommended an EnM framework based on EETs to ease their integration.

  • 2.
    Elnaggar, Mohamed
    et al.
    Department of Engineering, Palestine Technical College, Gaza Strip, Palestine.
    Edwan, Ezzaldeen
    Department of Engineering, Palestine Technical College, Gaza Strip, Palestine.
    Ritter, Matthias
    Department of Agricultural Economics, Humboldt-Universität zu Berlin, Berlin, Germany.
    Wind energy potential of Gaza using small wind turbines: A feasibility study2017In: Energies, E-ISSN 1996-1073, Vol. 10, no 8, article id 1229Article in journal (Refereed)
    Abstract [en]

    In this paper, we conduct a feasibility study of the wind energy potential in Gaza, which suffers from a severe shortage of energy supplies. Our calculated energy harvested from the wind is based on data for a typical meteorological year, which are fed into a small wind turbine of 5 kW power rating installable on the roof of residential buildings. The expected annual energy output at a height of 10 m amounts to 2695 kWh, but it can be increased by 35-125% at higher altitudes between 20 m and 70 m. The results also depict the great potential of wind energy to complement other renewable resources such as solar energy: The harvested energy of a wind system constitutes to up to 84% of the annual output of an equivalent power rating photovoltaic system and even outperforms the solar energy in the winter months. We also show that one wind turbine and one comparable photovoltaic system together could provide enough energy for 3.7 households. Hence, a combination of wind and solar energy could stabilize the decentralized energy production in Gaza. This is very important in a region where people seek to reach energy self-sufficient buildings due to the severe electricity shortage in the local grid.

  • 3.
    Helbing, Georg
    et al.
    Department of Agricultural Economics, Humboldt Universität zu Berlin, Berlin, Germany.
    Ritter, Matthias
    Department of Agricultural Economics, Humboldt Universität zu Berlin, Berlin, Germany.
    Deep Learning for fault detection in wind turbines2018In: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 98, p. 189-198Article in journal (Refereed)
    Abstract [en]

    Condition monitoring in wind turbines aims at detecting incipient faults at an early stage to improve maintenance. Artificial neural networks are a tool from machine learning that is frequently used for this purpose. Deep Learning is a machine learning paradigm based on deep neural networks that has shown great success at various applications over recent years. In this paper, we review unsupervised and supervised applications of artificial neural networks and in particular of Deep Learning to condition monitoring in wind turbines. We find that – despite a promising performance of supervised methods – unsupervised approaches are prevalent in the literature. To explain this phenomenon, we discuss a range of issues related to obtaining labelled data sets for supervised training, namely quality and access as well as labelling and class imbalance of operational data. Furthermore, we find that the application of Deep Learning to SCADA data is impeded by their relatively low dimensionality, and we suggest ways of working with higher-dimensional SCADA data. 

  • 4.
    Helbing, Georg
    et al.
    Department of Agricultural Economics, Humboldt Universität zu Berlin, Berlin, Germany.
    Ritter, Matthias
    Department of Agricultural Economics, Humboldt Universität zu Berlin, Berlin, Germany.
    Improving wind turbine power curve monitoring with standardisation2020In: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 145, p. 1040-1048Article in journal (Refereed)
    Abstract [en]

    Against the background of increasing cost pressure, condition monitoring is becoming increasingly relevant to the wind energy industry. The present study examines the role of wind turbulence and the non-constant variance of residuals in power curve monitoring. Power curve monitoring methods are classified and compared by means of Monte Carlo simulations. It is found that adjusting for the non-constant variance of residuals using standardisation may considerably improve the performance of control charts, no matter what method is used to generate them. Additionally, turbulence is found to be an important factor, and including it may further increase the performance of control charts. 

  • 5.
    Helbing, Georg
    et al.
    Department of Agricultural Economics, Humboldt-Universitt zu Berlin, Berlin, Germany.
    Ritter, Matthias
    Department of Agricultural Economics, Humboldt-Universitt zu Berlin, Berlin, Germany.
    Power curve monitoring with flexible EWMA control charts2017In: Proceedings - 2017 International Conference on Promising Electronic Technologies, ICPET 2017, IEEE, 2017, p. 124-128Conference paper (Refereed)
    Abstract [en]

    EWMA control charts have been used by several authors to monitor residuals of power curves for fault detection in wind turbines. In this study, we analyze the effect of non-constant variance in the residuals of a power curve on the performance of an EWMA control chart. We show that the variance can be modelled as a function of wind speed and use this insight to derive wind speed-adjusted control limits. A subsequent application of this procedure to a real data set spanning 2.5 years and on simulated data shows that it is able to slightly reduce the false alarm rate of the EWMA control chart.

  • 6.
    Holmberg, Roy
    Jönköping University, School of Engineering, JTH, Civil Engineering.
    Beräkning av värme- och fuktöverföring i roterande värmeväxlare1981In: VVS-Special, no 1, p. 37-42Article in journal (Other (popular scientific, debate etc.))
  • 7.
    Holmberg, Roy
    Jönköping University, School of Engineering, JTH, Civil Engineering.
    Frost i roterande värmeväxlare behöver inte ge påfrostning1982In: VVS: Tidskrift för energi- och vvs-teknik, ISSN 0346-4636, Vol. 53, no 6, p. 87-90Article in journal (Other academic)
  • 8.
    Holmberg, Roy B.
    Jönköping University, School of Engineering, JTH, Civil Engineering.
    Combined Heat and Mass Transfer in Regenerators with Hygroscopic Materials1979In: Journal of heat transfer, ISSN 0022-1481, E-ISSN 1528-8943, Vol. 101, p. 205-210Article in journal (Refereed)
  • 9.
    Holmberg, Roy B.
    Jönköping University, School of Engineering, JTH, Civil Engineering.
    Geringe Vereisungsgefahr bei Wärmerückgewinnern mit rotierenden Speichermassen1983In: HLH Heizung, Lüftung/Klima, Haustechnik, ISSN 1436-5103, Vol. 34, no 6, p. 242-246Article in journal (Other academic)
  • 10.
    Holmberg, Roy B.
    Jönköping University, School of Engineering, JTH, Civil Engineering.
    Heat Transfer in Liquid-coupled Indirect Heat Exchanger Systems1975In: Journal of heat transfer, ISSN 0022-1481, E-ISSN 1528-8943, Vol. 97, p. 499-503Article in journal (Refereed)
  • 11.
    Holmberg, Roy B.
    et al.
    Jönköping University, School of Engineering, JTH, Civil Engineering.
    Josefsson, Ingemar
    Rieselbefeuchter mit nichtbrennbaren Einsätzten1983In: TAB (Technik am Bau), ISSN 0341-2032, no 1, p. 47-49Article in journal (Other academic)
  • 12.
    Holmberg, Roy B.
    et al.
    Jönköping University, School of Engineering, JTH, Civil Engineering.
    Strindehag, Ove
    A Liquid coupled system for Heat Recovery from Exhaust Gases1975In: Building Services Engineer, Vol. 43Article in journal (Other (popular scientific, debate etc.))
  • 13.
    Holmberg, Roy
    et al.
    Jönköping University, School of Engineering, JTH, Civil Engineering.
    Strindehag, Ove
    Effektreglering i vätskekopplade värmeåtervinningssystem1977In: VVS, Vol. 48, p. 81-85, 93Article in journal (Other (popular scientific, debate etc.))
  • 14.
    Holmberg, Roy
    et al.
    Jönköping University, School of Engineering, JTH, Civil Engineering.
    Strindehag, Ove
    Vätskekopplade värmeåtervinningssystem1981In: VVS-Special, no 1, p. 21-28Article in journal (Other (popular scientific, debate etc.))
  • 15.
    Jalilzadehazhari, Elaheh
    et al.
    Linnaeus University, Växjö, Sweden.
    Vadiee, Amir
    Mälardalens högskola, Vasteras, Sweden.
    Johansson, Peter
    Jönköping University, School of Engineering, JTH, Civil Engineeering and Lighting Science.
    Achieving a trade-off construction solution using BIM, an optimization algorithm, and a multi-criteria decision-making method2019In: Buildings, E-ISSN 2075-5309, Vol. 9, no 4, p. 1-14, article id 81Article in journal (Refereed)
    Abstract [en]

    The Energy Performance of Building Directive obligated all European countries to reduce the energy requirements of buildings while simultaneously improving indoor environment quality. Any such improvements not only enhance the health of the occupants and their productivity, but also provide further economic benefits at the national level. Accomplishing this task requires a method that allows building professionals to resolve conflicts between visual and thermal comfort, energy demands, and life-cycle costs. To overcome these conflicts, this study exploits the incorporation of building information modelling (BIM), the design of experiments as an optimization algorithm, and the analytical hierarchy process (AHP) into a multi-criteria decision-making method. Any such incorporation can (i) create constructive communication between building professionals, such as architects, engineers, and energy experts; (ii) allow the analysis of the performance of multiple construction solutions with respect to visual and thermal comfort, energy demand, and life-cycle costs; and (iii) help to select a trade-off solution, thereby making a suitable decision. Three types of energy-efficient windows, and five types of ground floors, roofs, and external wall constructions were considered as optimization variables. The incorporation of several methods allowed the analysis of the performance of 375 construction solutions based on a combination of optimization variables, and helped to select a trade-off solution. The results showed the strength of incorporation for analyzing big-data through the intelligent use of BIM and a simulation in the field of the built environment, energy, and costs. However, when applying AHP, the results are strongly contingent on pairwise comparisons. 

  • 16.
    Jamshidi, Ali
    et al.
    Jönköping University, School of Engineering, JTH, Construction Engineering and Lighting Science. Jönköpings Universitet Kandidat student inom Byggnadsmekanik.
    Björk, Rasmus
    Jönköping University, School of Engineering, JTH, Construction Engineering and Lighting Science. Jönköpings Universitet Kandidat student inom Byggnadsmekanik .
    Energieffektivisering av villor: En fallstudie med fokus på investeringsbeslut baserat på energi- och ekonomiska analyser2023Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Introduktion (och mål) - Mänskligheten lever idag i en ohållbar värld och ställning tillmänsklighetens påverkan på jorden bör tas. Byggbranschen är en bov i denna fråga dåden står för cirka en tredjedel av värdens slutenergi. Världen står inför en kritiskenergiförbruknings omvändning där en övergång till energieffektivare lösningar äressentiella, ändå visar forskning på att denna övergång är saktfärdig. Samtidigt ser vien nedåtgående ekonomi med högre elpriser och lägre villapriser. Studien avser attåskådliggöra om ett analysverktyg med möjlighet till val av uppgraderingar haderesulterat i att flera kunder hade investerat i en mer energieffektiv villa.Metod - En fallstudie genomfördes på företaget A-Hus mest sålda villa i samarbetemed potentiella och nuvarande kunder. Studien använde litteratur- och dokumentstudiersamt utveckling av kalkyl- och analysprogram. En enkätinsamling genomfördes ocksåför att få kvalitativa svar om analysverktyget och valmöjligheternas påverkan påinvesteringsviljan.Resultat - Undersökningens resultat visar att en majoritet av deltagarna ansåg attkalkylprogrammet och dess analyser vägledde dem till att investera i en merenergieffektiv villa. En stor del av deltagarna valde att uppgradera sina villor direkteller indirekt med vägledning av kalkylprogrammet och dess analyser. Den mestpopulära uppgraderingskombinationen var att uppgradera väggtyp, fönstertyp, värmeoch ventilation samt solceller med andra ord alla möjliga uppgraderingar. En annankombination som var populär att uppgradera var fönstertyp, värme och ventilation samtsolceller. Analyser från kalkylprogrammet visade att båda dessauppgraderingskombinationer skulle ge en hög avkastning över livslängden avrespektive uppgraderings kombination och uppgraderingarna var lönsamma.Analys - En undersökning gjordes för att ta reda på i vilken utsträckning ettkalkylprogram med analysverktyg för energieffektivisering av hus påverkar potentiellahusköpares beslut. Resultatet visade att kalkylprogrammet med dess analyser ökadesannolikheten för att investera i en mer energieffektiv villa. En stor majoritet avundersökningsdeltagarna (85%) valde att uppgradera på grund av att analysverktygetfanns tillgängligt. De två vanligaste kombinationerna av byggnadsdelstillval sompotentiella husköpare var villiga att investera i var väggtyp, fönstertyp, värme- ochventilationstillval och solcellstillval, samt fönstertyp, värme- och ventilationstillval ochsolcellstillval.Diskussion - Målgruppen ifrågasätts och en mer relevant målgrupp föreslås vara desom aktivt söker att köpa en villa. Medvetenheten hos undersökningsdeltagarna kan hapåverkat resultaten, och det föreslås att skapa realistiska scenarier för att minimerapåverkan. Behovet av en kontrollgrupp för att jämföra resultaten och bedömakalkylprogrammets effektivitet diskuteras också. Studien diskuterar använda metoderför datainsamling och föreslår att triangulering och intervjuer med deltagare skullekunna stärka validiteten. För att öka både den externa och interna validiteten föreslåsatt använda ett större urval och inkludera en kontrollgrupp.

  • 17.
    Johansson, Rasmus
    et al.
    Jönköping University, School of Engineering, JTH, Industrial Product Development, Production and Design, JTH, Product design and development (PDD).
    Söderberg, Johannes
    Jönköping University, School of Engineering, JTH, Industrial Product Development, Production and Design, JTH, Product design and development (PDD).
    Portable Power-Supply: Framtidens lösning för kommersiella robotgräsklippare.2023Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Globe technologies is a company that sells products in the gardening market for both commercial and professional use. This study focuses on developing a battery powered accessory for autonomous mowers. The study investigates the possibility to use autonomous mowers in green spaces that do not have access to power by the grid. To provide the autonomous mower with power the study introduces a portable power supply that provides power to the mower.  The development of the portable power supply starts with a market analysis and that lays the foundation for the project. The report continues with the development of the actual product and finishes off with testing of a prototype. To get the product that is wanted relevant theories and methods is investigated and applied. During the thesis a number of iterations of the product are designed to meet the demands of the requirement specification.

    Download full text (pdf)
    Portable Power Supply
  • 18.
    Joshi, S. V.
    et al.
    School of Mechanical and Building Sciences, VIT University, Vellore, India.
    Sainis, Salil
    School of Mechanical and Building Sciences, VIT University, Vellore, India.
    D'Souza, M.
    Suzlon Energy Limited, One Earth, Pune, India.
    Quantitative performance evaluation of a wind turbine generator cluster using statistical techniques2014In: Energy Procedia, ISSN 1876-6102, Vol. 54, p. 211-220Article in journal (Refereed)
    Abstract [en]

    This report dissects the analysis of annual performance of a cluster of wind turbine generators operated by Suzlon Energy Limited to troubleshoot shortfalls in the predicted generation of individual machines for the fiscal year of 2011-12. The first phase involved an estimation of the annual energy production using wind resource assessment on the commercial software Wind Atlas, Analysis and Application Program (WAsP). Comparison of the Annual Energy Production (AEP) with direct extrapolation of monthly generation to centum machine and grid availability highlighted negative inconsistency between the two in the case of five machines. Detailed study of their data histories indicated the reason to be coarse extrapolation and generation curtailment, although the latter is a minor contributor. The second phase consists of quantification of these losses for the concerned machines using statistical extrapolation and a variety of data approaches. A qualitative comparison of the methods is presented based on accuracy and utility. It is concluded that correlation of average hub-height wind velocities with the concerned machine's generation yields the most reliable and professionally useful results. Also, the advantages and shortcomings of the other methods have been discussed. 

  • 19.
    Jägerbrand, Annika K.
    et al.
    Statens väg- och transportforskningsinstitut, Miljö, MILJÖ.
    Hellman, Fredrik
    Statens väg- och transportforskningsinstitut, Väg- och banteknik, VBA.
    Energiutvinning ur vägar och vägmiljöer: en kunskapsöversikt2014Report (Other academic)
    Abstract [en]

    The report aims to identify new technologies for energy harvesting and the ability to use them in the road and the surrounding road area. The survey focuses on the materials and methods that may be used in the Swedish (cold) climate. The report can be useful for planning of new infrastructure when you want to make use of renewable energy and wants to reduce the environmental impact. Considering today’s technological conditions, the following techniques may be relevant: photovoltaics, geothermal energy, piezoelectric technology, wind energy or bioenergy. There are, however, many factors holding back the development of new innovative systems for energy production in roads and their environment. Some important factors are for example that maintenance costs will increase or that the maintenance of the road will become more difficult.

    Download full text (pdf)
    FULLTEXT01
  • 20.
    Lora, Ruben
    et al.
    Jönköping University, School of Engineering, JTH, Mechanical Engineering.
    Namjoshi, Jayesh
    Jönköping University, School of Engineering, JTH, Mechanical Engineering.
    Simulation of Residual Stresses in Castings2008Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This work presents a study and implementation of the simulation of residual stresses in castings. The objects of study are a cast iron truck Hub part (provided by the company Volvo 3P) and an optimized version of the Hub resulting from the application of a topology optimization process. The models are solved through an uncoupled thermo-mechanical solidification analysis, performed both in the FE commercial software Abaqus and the FD commercial software Magmasoft and the results are compared. First, a thermal analysis is carried out where the casting is cooled down from a super-heated temperature to room temperature. The thermal history obtained, is then used as an external force to calculate the residual stresses by means of a quasi-static mechanical analysis, using a J2-plasticity model. The simulation procedures are explained through a simplified model of the Hub and then applied to the geometries of interest. A results comparison between the original Hub and its optimized version is also presented. The theoretical base is given in this work as well as detailed implementation procedures. The results shows that the part subjected to the topology optimization process develop less residual stresses than its original version.

    Download full text (pdf)
    FULLTEXT01
  • 21.
    Mansi, Ghada
    et al.
    Engineering Program Department, Palestine Technical College, Deir El-Balah, Palestine.
    Edwan, Ezzaldeen
    Engineering Program Department, Palestine Technical College, Deir El-Balah, Palestine.
    Elnaggar, Mohamed
    Engineering Program Department, Palestine Technical College, Deir El-Balah, Palestine.
    Ritter, Matthias
    Department of Agricultural Economics, Humboldt-Universität zu Berlin, Berlin, Germany.
    Design of COTS Vertical Axis Wind Turbine for Urban Areas2018In: Proceedings - 2018 International Conference on Promising Electronic Technologies, ICPET 2018, IEEE, 2018, p. 69-73Conference paper (Refereed)
    Abstract [en]

    In this paper we describe the design of a vertical axis wind turbine (VAWT) that fits residential areas. Such turbines are needed in regions with dense population such as Gaza Strip where the majority of the population are living in urban areas and they seek to reach energy self-sufficient buildings due to the severe electricity shortage in the local grid. The main consideration for a VAWT wind turbine to be suitable for urban areas is the safety factor. Another consideration is being able to turn and produce electricity at low wind speeds. Those two factors will shape the design of the VAWT wind turbine. The designed wind turbine should be compact enough to be installed on rooftops. A target power rating of 5 k Watt is set for the wind turbine as a considerable amount of power to supply a typical residential home. The efficiency of the designed wind turbine is validated experimentally by the recorded wind speeds from an anemometer and the estimated harvested power from the turbine itself. Further schemes and modifications on the design are suggested for improving the power efficiency.

  • 22.
    Myrna, Olena
    et al.
    Department of Agricultural Economics, Humboldt-Universität zu Berlin, Berlin, Germany.
    Odening, Martin
    Department of Agricultural Economics, Humboldt-Universität zu Berlin, Berlin, Germany.
    Ritter, Matthias
    Department of Agricultural Economics, Humboldt-Universität zu Berlin, Berlin, Germany.
    The influence of wind energy and biogas on farmland prices2019In: Land, E-ISSN 2073-445X, Vol. 8, no 1, article id 19Article in journal (Refereed)
    Abstract [en]

    In the context of the rapid development of renewable energy in Germany in the last decade, and increased concerns regarding its potential impacts on farmland prices, this paper investigates the impact of wind energy and biogas production on agricultural land purchasing prices. To quantify the possible impact of the cumulative capacity of wind turbines and biogas plants on arable land prices in Saxony-Anhalt, we estimate a community-based and a transaction-based model using spatial econometrics and ordinary least squares. Based on data from 2007 to 2016, our analysis shows that a higher cumulative capacity of wind turbines in communities leads to higher farmland transaction prices, though the effect is very small: if the average cumulative capacity of wind turbines per community doubles, we expect that farmland prices per hectare increase by 0.4%. Plots that are directly affected by a wind turbine or part of a regional development plan, however, experience strong price increases.

  • 23.
    Mølmen, L.
    et al.
    RISE Research Institute of Sweden, Borås/Lund, Sweden.
    Alexandersson, A.
    RISE Research Institute of Sweden, Borås/Lund, Sweden.
    Leisner, Peter
    Jönköping University, School of Engineering, JTH, Materials and Manufacturing. RISE Research Institute of Sweden, Borås/Lund, Sweden.
    Surface technology should improve PEM fuel cell performance2019In: Transactions of the Institute of Metal Finishing, ISSN 0020-2967, E-ISSN 1745-9192, Vol. 97, no 3, p. 112-114Article in journal (Refereed)
    Abstract [en]

    Leading industrial nations are investing in hydrogen technology as energy storage solution with fuel cells as the main converter to electric energy. Improvements in the performance of the key components: electrode catalyst, bipolar plates and polymer electrolyte membrane are needed to reduce costs for mass-market introduction. Consequently, surface technology has an essential role in meeting the goals. 

  • 24.
    Mølmen, Live
    et al.
    Jönköping University, School of Engineering, JTH, Materials and Manufacturing. RISE Res Inst Sweden, Dept Electrificat & Reliabil, Boras, Sweden.
    Eiler, K.
    Univ Autonoma Barcelona, Dept Fis, Bellaterra, Spain.
    Fast, L.
    RISE Res Inst Sweden, Dept Electrificat & Reliabil, Boras, Sweden..
    Leisner, Peter
    Jönköping University, School of Engineering, JTH, Materials and Manufacturing.
    Pellicer, E.
    Univ Autonoma Barcelona, Dept Fis, Bellaterra, Spain.
    Recent advances in catalyst materials for proton exchange membrane fuel cells2021In: APL Materials, E-ISSN 2166-532X, Vol. 9, no 4, article id 040702Article in journal (Refereed)
    Abstract [en]

    Research on fuel cell technology is constantly gaining importance, while global emission requirements are becoming more and more restrictive. For environmentally neutral proton exchange membrane fuel cells (PEMFCs) to become a competitive technology, sustainable infrastructures need to be established. One of the main showstoppers is the utilization of the rare and therefore costly precious metal Pt as the key element in the electrocatalysis of hydrogen and oxygen. A huge amount of research is done on immensely reducing or even replacing Pt for future PEMFC technology. In this research update, the progress on oxygen reduction reaction catalysts in acidic media over the past two years is reviewed, with special attention to their durability.

  • 25.
    Nordh, Andreas
    Jönköping University, School of Engineering, JTH, Product Development.
    CFD and Experimental Study of Heat Exchangers for Transient Heating Application2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Global warming is a problem to the environment and a threat to the lifestyle people have today. The average temperature around the world is increasing and it is mainly because the increased amount of greenhouse gases in the atmosphere. Emissions of greenhouse gases are mainly caused by using fossil fuels to create electricity. The problem investigated in this thesis study originates from a company that intends to create electricity by means of renewable energy sources. The energy is transferred from thermal energy to kinetic energy and from the kinetic energy, electricity is generated with a generator.

    The company’s system is operating with standard components with insufficient efficiency. Advancement to the next level is depending on finding a solution to improve the performance of their main component in the system. The main component is a brazed plate heat exchanger that is used to transfer heat from one medium to another. Process cycle is strongly dependent on the time it takes to heat and cool the media inside the heat exchanger. The objective of this thesis is to analyze the transient behavior of heat exchangers and with this information compare two construction types to show what type is more appropriate to use inside the system.

    Evaluation is made experimentally and with means of Computational-Fluid-Dynamics (CFD) where two CFD-tools are evaluated. To create a reference case to compare results against, the model of the heat exchanger used today is created as a reference model. The reference model is compared to experimental measurement to show the validity of the simulation set-up. From design guidelines received from the company, an alternative construction type is chosen and compared towards the plate heat exchanger. The tube-fin heat exchanger with continuous plates across a bundle of tubes is parametrically studied. The best-determined concept is compared to the plate heat exchanger.

    Evaluation of the CFD-tools shows that two identical geometries with identical set-up can give a difference in the results based on the tool chosen for the simulation. It is shown by results that the transient behavior of heat exchangers in a CFD-simulation have a general agreement with experimental results. The agreement depends on the control of the experimental set-up. The comparison between the best concept and the reference model shows that the difference in average gas temperature during 5 seconds of transient heating is at most 1.1 degrees. Construction types is therefore also evaluated on material-cost, thermal mass and guidance from heat exchanger handbooks.

    The results indicate that the tube-fin heat exchanger is more suitable to use in the system. It reduces material, reduces environmental impact and matches the performance of the industrial plate heat exchanger.

  • 26.
    Pieralli, Simone
    et al.
    Humboldt-Universität zu Berlin, Department of Agricultural Economics, Berlin, Germany.
    Ritter, Matthias
    Humboldt-Universität zu Berlin, Department of Agricultural Economics, Berlin, Germany.
    Odening, Martin
    Humboldt-Universität zu Berlin, Department of Agricultural Economics, Berlin, Germany.
    Efficiency of wind power production and its determinants2015In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 90, p. 429-438Article in journal (Refereed)
    Abstract [en]

    This article examines the efficiency of wind energy production. Using non-convex efficiency analysis, we quantify production losses for 19 wind turbines in four wind parks across Germany. In a second stage regression, we adapt the linear regression results of Kneip, Simar, and Wilson (2015) to explain electricity losses by means of a bias-corrected truncated regression analysis. The results show that electricity losses amount to 27% of the maximal producible electricity. Most of these losses are from changing wind conditions, while 6% are from turbine errors.

  • 27.
    Ragnarsson, Isac
    et al.
    Jönköping University, School of Engineering, JTH, Industrial Product Development, Production and Design, JTH, Product design and development (PDD).
    Rosdahl, Viktor
    Jönköping University, School of Engineering, JTH, Industrial Product Development, Production and Design, JTH, Product design and development (PDD).
    Bränslecellsdriven fältladdare: Koncept för laddning på fältet2023Independent thesis Basic level (degree of Bachelor), 180 HE creditsStudent thesis
    Abstract [en]

    This report will investigate and go through the steps required to develop several concepts for afuel cell-powered battery charger to be used in the field by Husqvarna AB. The purpose is togather information about available fuel cell technologies and provide an understanding of howthese concepts could look in both the present and the future. Through an examination ofprevious studies in the field, it has been determined that the most suitable types of fuel cells arePEMFC and DMFC. Additional information has been collected from various sources, such asthe internet, books, and through contact with fuel cell manufacturers and Husqvarna AB.Three different fuel cells were chosen, each of which was assigned a unique concept. Two ofthese concepts are more future-oriented, aiming to provide a better idea of how the productcould look if the requirements are strictly followed. The third concept demonstrates how theproduct would need to appear and the features required to be more suitable for the present.Finally, a comparison was made where the technical characteristics of concepts were pittedagainst each other, and weighted requirements showed that the concept containing EFOY´s12000 pro fuel cell moved forward.

    Download full text (pdf)
    Bränslecellsdriven fältladdare
  • 28.
    Ritter, Matthias
    et al.
    Humboldt-Universität zu Berlin, Department of Agricultural Economics, Berlin, Germany.
    Deckert, Lars
    4initia GmbH, Berlin, Germany.
    Site assessment, turbine selection, and local feed-in tariffs through the wind energy index2017In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 185, p. 1087-1099Article in journal (Refereed)
    Abstract [en]

    Since wind energy is rapidly growing, new wind farms are installed worldwide and a discussion is going on concerning the optimal political framework to promote this development. In this paper, we present a wind energy index, which is supportive for wind farm planners, operators, and policy-makers. Based on long-term and low-scale reanalysis wind speed data from MERRA and true production data, it can predict the expected wind energy production for every location and turbine type. After an in-sample and out-of-sample evaluation of the index performance, it is applied to assess the wind energy potential of locations in Germany, to compare different turbine types, and to derive the required compensation in terms of locally different feed-in tariffs. We show that in many parts of South Germany, profitability of new wind farms cannot be achieved given the current legal situation. 

  • 29.
    Ritter, Matthias
    et al.
    Department für Agrarökonomie, Humboldt-Universität zu Berlin, Berlin.
    Hüttel, Silke
    Universität Rostock, Rostock.
    Walter, Marian
    Department für Agrarökonomie, Humboldt-Universität zu Berlin, Berlin.
    Odening, Martin
    Department für Agrarökonomie, Humboldt-Universität zu Berlin, Berlin.
    Der Einfluss von Windkraftanlagen auf landwirtschaftliche Bodenpreise [The influence of wind energy on agricultural land prices]2015In: Berichte über Landwirtschaft, ISSN 0005-9080, Vol. 93, no 3Article in journal (Refereed)
    Abstract [en]

    This study sets out to analyze the trend in farmland prices in one of the eastern states of Germany, Brandenburg, between the years 2000 and 2010. Apart from the usual price determinants, we consider especially the influence of wind power generation. Based on regression analysis, we find a significant positive correlation between the scope of the wind energy and the level of the purchasing prices. The effects are also broken down into a stock, extension and potential effect. It is shown that, on average, the use of wind energy in Brandenburg led to an increase of farmland prices of about five percent, although this effect has regional differences depending on the local wind turbine density.

  • 30.
    Ritter, Matthias
    et al.
    Department of Agricultural Economics and Rural Development, Georg-August Universität Göttingen, Göttingen, Germany; Department of Agricultural Economics, Humboldt-Universität zu Berlin, Berlin, Germany.
    Mußhoff, O.
    Department of Agricultural Economics and Rural Development, Georg-August Universität Göttingen, Göttingen, Germany.
    Odening, Martin
    Department of Agricultural Economics, Humboldt-Universität zu Berlin, Berlin, Germany.
    Minimizing Geographical Basis Using A Multi-Site Rainfall Model2014In: Computational Economics, ISSN 0927-7099, E-ISSN 1572-9974, Vol. 44, no 1, p. 67-86Article in journal (Refereed)
    Abstract [en]

    It is well known that the hedging effectiveness of weather derivatives is interfered by the existence of geographical basis risk, i.e., the deviation of weather conditions at different locations. In this paper, we explore how geographical basis risk of rainfall based derivatives can be reduced by regional diversification. Minimizing geographical basis risk requires knowledge of the joint distribution of rainfall at different locations. For that purpose, we estimate a daily multi-site rainfall model from which optimal portfolio weights are derived. We find that this method allows to reduce geographical basis risk more efficiently than simpler approaches as, for example, inverse distance weighting. 

  • 31.
    Ritter, Matthias
    et al.
    Department of Agricultural Economics, Faculty of Life Sciences, Humboldt-Universität zu Berlin, Berlin, Germany.
    Pieralli, Simone
    Department of Agricultural Economics, Faculty of Life Sciences, Humboldt-Universität zu Berlin, Berlin, Germany.
    Odening, Martin
    Department of Agricultural Economics, Faculty of Life Sciences, Humboldt-Universität zu Berlin, Berlin, Germany.
    Neighborhood effects in wind farm performance: A regression approach2017In: Energies, E-ISSN 1996-1073, Vol. 10, no 3, article id 365Article in journal (Refereed)
    Abstract [en]

    The optimization of turbine density in wind farms entails a trade-off between the usage of scarce, expensive land and power losses through turbine wake effects. A quantification and prediction of the wake effect, however, is challenging because of the complex aerodynamic nature of the interdependencies of turbines. In this paper, we propose a parsimonious data driven regression wake model that can be used to predict production losses of existing and potential wind farms. Motivated by simple engineering wake models, the predicting variables are wind speed, the turbine alignment angle, and distance. By utilizing data from two wind farms in Germany, we show that our models can compete with the standard Jensen model in predicting wake effect losses. A scenario analysis reveals that a distance between turbines can be reduced by up to three times the rotor size, without entailing substantial production losses. In contrast, an unfavorable configuration of turbines with respect to the main wind direction can result in production losses that are much higher than in an optimal case.

  • 32.
    Ritter, Matthias
    et al.
    Humboldt-Universität zu Berlin, Berlin, Germany.
    Shen, Z.
    Humboldt-Universität zu Berlin, Berlin, Germany.
    Cabrera, B. L.
    Humboldt-Universität zu Berlin, Berlin, Germany.
    Odening, M.
    Humboldt-Universität zu Berlin, Berlin, Germany.
    Deckert, L.
    4inita GmbH, Berlin, Germany.
    A New Approach to Assess Wind Energy Potential2015In: Energy Procedia, Elsevier, 2015, p. 671-676Conference paper (Refereed)
    Abstract [en]

    To meet the increasing global demand for renewable energy, such as wind energy, an increasing number of wind parks are being constructed worldwide. Finding a suitable location requires a detailed and often costly analysis of local wind conditions. Plain average wind speed maps cannot provide a precise forecast of wind power because of the non-linear relationship between wind speed and production. We suggest a novel, globally feasible approach to assess the local wind energy potential: First, meteorological reanalysis data are applied to obtain long-term low-scale wind speed data at specific turbine locations and hub heights. Second, the relation between wind data and energy production is for the first time determined via a five parameter logistic function using actual high-frequency energy production data. The resulting wind energy index allows for a turbine-specific estimation of the expected wind power at an unobserved location. A map of the wind power potential for Germany exemplifies our approach. 

  • 33.
    Ritter, Matthias
    et al.
    Humboldt-Universität zu Berlin, Department of Agricultural Economics, Berlin, Germany.
    Shen, Zhiwei
    Humboldt-Universität zu Berlin, Department of Agricultural Economics, Berlin, Germany.
    López Cabrera, Brenda
    Humboldt-Universität zu Berlin, School of Business and Economics, Ladislaus von Bortkiewicz Chair of Statistics, Berlin, Germany.
    Odening, Martin
    Humboldt-Universität zu Berlin, Department of Agricultural Economics, Berlin, Germany.
    Deckert, Lars
    4initia GmbH, Berlin, Germany.
    Designing an index for assessing wind energy potential2015In: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 83, p. 416-424Article in journal (Refereed)
    Abstract [en]

    To meet the increasing global demand for renewable energy, such as wind energy, an increasing number of wind parks are being constructed worldwide. Finding a suitable location requires a detailed and often costly analysis of local wind conditions. Plain average wind speed maps cannot provide a precise forecast of wind power because of the non-linear relationship between wind speed and production. We suggest a new approach to assess the local wind energy potential. First, meteorological reanalysis data are applied to obtain long-term low-scale wind speed data at specific turbine locations and hub heights. Second, the relation between wind data and energy production is determined via a five parameter logistic function using actual high-frequency energy production data. The resulting wind energy index allows for a turbine-specific estimation of the expected wind power at an unobserved location. A map of the wind power potential for Germany exemplifies our approach.

  • 34.
    Shen, Zhiwei
    et al.
    Humboldt-Universität zu Berlin, Department of Agricultural Economics, Berlin, Germany.
    Ritter, Matthias
    Humboldt-Universität zu Berlin, Department of Agricultural Economics, Berlin, Germany.
    Forecasting volatility of wind power production2016In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 176, p. 295-308Article in journal (Refereed)
    Abstract [en]

    Given the increasing share of wind energy in the portfolio of energy sources, there is the need for a more thorough understanding of its uncertainties due to changing weather conditions. To account for the uncertainty in predicting wind power production, this article examines the volatility forecasting abilities of different GARCH-type models for wind power production. Moreover, due to characteristic features of the wind power process, such as heteroscedasticity and nonlinearity, we also investigate the use of a Markov regime-switching GARCH (MRS-GARCH) model on forecasting volatility of wind power. Realized volatility, which is derived from lower-scale data, serves as a benchmark for latent volatility. We find that the MRS-GARCH model significantly outperforms traditional GARCH models in predicting the volatility of wind power, while the exponential GARCH model is superior among traditional GARCH models.

  • 35.
    Wilke, Alina
    et al.
    Humboldt-Universität zu Berlin, Faculty of Life Sciences, Department of Agricultural Economics, Berlin, Germany.
    Shen, Zhiwei
    Humboldt-Universität zu Berlin, Faculty of Life Sciences, Department of Agricultural Economics, Berlin, Germany.
    Ritter, Matthias
    Humboldt-Universität zu Berlin, Faculty of Life Sciences, Department of Agricultural Economics, Berlin, Germany.
    How Much Can Small-Scale Wind Energy Production Contribute to Energy Supply in Cities? A Case Study of Berlin2020Report (Other academic)
    Abstract [en]

    In light of the Paris Agreement, many cities have undertaken initiatives to become climate-neutral, making decentralized urban energy production more relevant. This paper addresses the potential of urban wind energy production with small wind turbines, using Berlin as an example. Based on a detailed dataset of all buildings and the hourly wind speed on a 1 km² grid, the potential energy production of each building and Berlin as a whole is assessed. The results show that multiple turbines on suitable buildings are necessary to cover a considerable amount of all households’ energy consumption. Nevertheless, the use of small wind turbines is currently beneficial for individual households to reduce their energy expenditures.

  • 36.
    Wilke, Alina
    et al.
    Department of Macroeconomic Theory and Policy, Schumpeter School of Business and Economics, Bergische Universität Wuppertal, Wuppertal, Germany.
    Shen, Zhiwei
    Department of Agricultural Economics, Faculty of Life Sciences, Humboldt-Universität zu Berlin, Berlin, Germany.
    Ritter, Matthias
    Department of Agricultural Economics, Faculty of Life Sciences, Humboldt-Universität zu Berlin, Berlin, Germany.
    How much can small-scale wind energy production contribute to energy supply in cities?: A case study of Berlin2021In: Energies, E-ISSN 1996-1073, Vol. 14, no 17, article id 5523Article in journal (Refereed)
    Abstract [en]

    In light of the global effort to limit the temperature rise, many cities have undertaken initiatives to become climate-neutral, making decentralized urban energy production more relevant. This paper addresses the potential of urban wind energy production with small wind turbines, using Berlin as an example. A complete framework from data selection to economic feasibility is constructed to enable the empirical assessment of wind energy for individual buildings and Berlin as a whole. Based on a detailed dataset of all buildings and hourly wind speed on a 1 km² grid, the results show that multiple turbines on suitable buildings can significantly contribute to households’ energy consumption but fall short of covering the full demand. For individual households, our economic evaluation strongly recommends the self-consumption of the produced electricity. The findings suggest that while the use of small wind turbines should be continuously encouraged, exploring other renewable resources or combination of wind and photovoltaic energy in the urban environment remains important.

1 - 36 of 36
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