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  • 51.
    Gadd, Henrik
    et al.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Energiteknik.
    Werner, Sven
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS).
    Heat load patterns in district heating substations2013Inngår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 108, s. 176-183Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Future smart energy grids will require more information exchange between interfaces in the energy system. One interface where dearth of information exists is in district heating substations, being the interfaces between the distribution network and the customer building heating systems. Previously, manual meter readings were collected once or a few times a year. Today, automatic meter readings are available resulting in low cost hourly meter reading data. In a district heating system, errors and deviations in customer substations propagates through the network to the heat supply plants. In order to reduce future customer and heat supplier costs, a demand appears for smart functions identifying errors and deviations in the substations. Hereby, also a research demand appears for defining normal and abnormal heat load patterns in customer substations. The main purpose with this article is to perform an introductory analysis of several high resolution measurements in order to provide valuable information about substations for creating future applications in smart heat grids. One year of hourly heat meter readings from 141 substations in two district heating networks were analysed. The connected customer buildings were classified into five different customer categories and four typical heat load patterns were identified. Two descriptive parameters, annual relative daily variation and annual relative seasonal variation, were defined from each 1 year sequence for identifying normal and abnormal heat load patterns. The three major conclusions are associated both with the method used and the objects analysed. First, normal heat load patterns vary with applied control strategy, season, and customer category. Second, it is possible to identify obvious outliers compared to normal heat loads with the two descriptive parameters used in this initial analysis. Third, the developed method can probably be enhanced by redefining the customer categories by their indoor activities.

  • 52.
    Gadd, Henrik
    et al.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Energivetenskap.
    Werner, Sven
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Energivetenskap.
    Thermal energy storage systems for district heating and cooling2015Inngår i: Advances in Thermal Energy Storage Systems: Methods and Applications / [ed] Luisa F. Cabeza, Cambridge: Woodhead Publishing Limited, 2015, 1, s. 467-478Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    The context for this chapter is the current use and typical applications of thermal energy storages within contemporary district heating and cooling systems in the Nordic countries. Examples include a new assessment method, distributed heat storages, and hourly, daily, weekly, and seasonal heat and cold storages. Specific sizes have been estimated for 209 heat storages and 9 cold storages.

  • 53.
    Ghadirinejad, Nickyar
    et al.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap.
    Ottermo, Fredric
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Rydberglaboratoriet för tillämpad naturvetenskap (RLAS).
    Hoseinzade, A.
    University of Sistan and Baluchestan, Zahedan, Iran.
    Experimental Evaluation, Simulation and Statistical Analysis of a Humidification-Dehumidification Solar Desalination System2018Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Inspired by the precipitation cycle, the Humidification-Dehumidification (HDH) method is based on evaporation and consecutive condensation in a natural loop. The heat input to the system is provided by a solar collector, making the system suitable for remote locations with access to sea water and good insolation. In this study investigated parameters included temperatures and flow rates of cooling water, cycled air, and water intake to humidifier, as well as the height of packed bed column. A series of simulations has been performed in the ASPEN Plus software, in order to obtain optimum physical parameters in this desalination system. The experimental results showed that at constant heat flux and optimum air flow rate, three parameters have strong influence on the production of distilled water: the flow rate of cooling water, the flow rate of water inlet and its temperature augmentation. Moreover, although increasing flow rate of cooling water leads to an increase in the distilled water flow rate, this effect is mitigated at high rates. The most reliable Height Equivalent to a Theoretical Plate (HETP) model of random packing has been found by opting for the model of Mangers & Ponter. The estimated error of the model in predicting the height of the packed bed was less than 4%. Regarding closed versus open air flow; the closed air system provided an efficiency of distilled water production up to 15% higher than the open air system for the same conditions. This increase is a result of prevention of the loss of air humidity at the condenser outlet. A regression analysis was performed, which indicates that the HDH system can be well described by a linear model for the logarithm of the rate of desalinated water. The variables used are the saline water flow rate, the heat transfer rate in the solar collector and the air flow rate. The adjusted R-squared of the fit was computed as 89.8%.

  • 54. Glöersen, Erik
    et al.
    Johnsson, Pehr-Erik
    Hyberger, Joacim
    Biogas på Wapnö: Analys av framtida energisystem2012Independent thesis Basic level (degree of Bachelor), 15 poäng / 22,5 hpOppgave
    Abstract [en]

    Considering that the price and demand for energy gradually has risen over the past decade and a wider discussion about the human impact on the environment has become increasingly more important and given a clearer role in modern society. This has contributed to increased incentives to reduce the use of fossil fuels and increase the use of renewable energy.The agriculture currently accounts for 20 % of Sweden's total greenhouse gas emissions. A way for an agricultural company like Wapnö AB to reduce their emissions could be to utilize existing renewable energy sources within their own premises.The report's aim is to create an energy audit of Wapnö’s existing energy system and how it changes with a future biogas plant in operation. The energy audit is used to illustrate how the company’s climate footprint could change. The report also investigates the economics of different heating options for the biogas process and the completion of the current refrigeration compressors with a heat-driven chiller, all to increase the usage of the waste heat from the cogeneration, and minimize the need of purchased energy.The results show that Wapnö can reduce their carbon emissions with 5600 tons of carbon dioxide per year with a future biogas plant in operation. The results also show that the waste heat, combined with a heat pump, is the most cost efficient way to heat the biogas process. Furthermore, the report also shows that the investment in an absorption chiller will be refunded within approximately 6 years, and that in a comparison of the reduced climate impact of either cogeneration or production of vehicle gas, at Wapnö, cogeneration provides a slightly larger reduction of greenhouse gas emissions.

  • 55.
    Gomez, Fabrizio
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap.
    Optimization of a grid connected residential battery storage system in Sweden: Home Energy Management System Approach2018Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    The market for energy production has experienced relevant changes to reach more sustainable characteristics, during the last two decades. In this context, residential photovoltaic (PV) system has gained popularity as a practical and profitable alternative to complement the electric supply from the grid. In the same line, the seasonal and variable nature of PV supply generates an interest in BESS-battery energy storage systems.The aim with this thesis is to investigate HEMS-home energy management system for a residential electricity production using PV and storage in Sweden. HEMS allows residential customer and producer to sell or buy energy to minimize the final electricity bill. The capacityof BESS and the scheduling are optimized by using a proposed algorithm. Results gained indicate that factors such as household electricity demand and allocation during the day, electricity price, and tariff scheme are the critical variables to consider in the design of the BESS system. Optimal battery capacities obtained are within the range of available battery market stock-sizes. However, several of the standard battery capacities of the leading manufacturers are oversized for this case. For Swedish context, a BESS installation cost below 270 €/kWh generates saving on the annual electricity bill of having BESS in comparison with not using BESS. In addition, the daily charge of EV, electric vehicle, was studied to see if a higher demand for household electricity could generate an optimal capacity and higher savings.

  • 56.
    Gong, Mei
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Rydberglaboratoriet för tillämpad naturvetenskap (RLAS).
    New system solution for biomass CHP plant2019Rapport (Annet vitenskapelig)
    Abstract [en]

    The main propose with this pre-study was to assess a new Chinese conceptconcerning Combined Heat and Power (CHP) plants for typical Swedish conditionswith biomass as fuel. The new enhancement is to use a large absorption heat pumpfor the final heat supply instead of the turbine condenser. More heat can then berecovered from the three units that will deliver the heat (the flue gas condenser, theturbine condenser and the absorption heat pump). So far, this new CHP solution hasnever been implemented outside China.For this pre-study, the simulation model was elaborated on design data from theÖrtofta biomass CHP plant outside Lund. The results show that Chinese conceptwill provide the higher conversion efficiency, but with lower power-to-heat ratio.The main benefit is that more heat can be recycled from the flue gas condenser. Thepayback time of installing absorption heat pump is always over eight years withinexpected intervals for alternative costs for electricity and heat.The Chinese concept is less suitable for the Swedish context with biomass backpressureCHP plants, since the proportion of lost electricity becomes rather high.The Chinese context with utilization of existing condensation turbines is stillinteresting, since condenser heat can be recycled without major modification ofexisting turbines.

  • 57.
    Gong, Mei
    et al.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Energivetenskap.
    Wall, Göran
    Öxbo, Lerum, Sverige.
    Exergy Analysis of the Supply of Energy and Material Resources in the Swedish Society2016Inngår i: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 9, nr 9, artikkel-id 707Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Exergy is applied to the Swedish energy supply system for the period 1970–2013. Exergy flow diagrams for the systems of electricity and district heating as well as for the total supply system of energy and material resources for 2012 are presented. The share of renewable use has increased in both electricity and district heat production. The resource use is discussed in four sectors: residential and service, transportation, industry and agriculture. The resource use is also analyzed with respect to exergy efficiency and renewable share. The total exergy input of energy and material resources amounts to about 2700 PJ of which about 530 PJ was used for final consumption in 2012. The results are also compared with similar studies. Even though the share of renewable resource use has increased from 42% in 1980 to 47% in 2012, poor efficiency is still occurring in transportation, space heating, and food production. A strong dependence on fossil and nuclear fuels also implies a serious lack of sustainability. A more exergy efficient technology and a higher renewable energy share are needed in order to become a more sustainable society.

  • 58.
    Gong, Mei
    et al.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Energiteknik.
    Wall, Göran
    Öxbo gård, Härryda, Sweden.
    Life Cycle Exergy Analysis of Solar Energy Systems2014Inngår i: Journal of Fundamentals of Renewable Energy and Applications, ISSN 2090-4533, E-ISSN 2090-4541, Vol. 5, nr 1, artikkel-id 1000146Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Exergy concepts and exergy based methods are applied to energy systems to evaluate their level of sustainability. Life Cycle Exergy Analysis (LCEA) is a method that combines LCA with exergy, and it is applied to solar energy systems. It offers an excellent visualization of the exergy flows involved over the complete life cycle of a product or service. The energy and exergy used in production, operation and destruction must be paid back during life time in order to besustainable. The exergy of the material that is being engaged by the system will turn up as a product and available for recycling in the destruction stage. LCEA shows that solar thermal plants have much longer exergy payback time than energy payback time, 15.4 and 3.5 years respectively. Energy based analysis may lead to false assumptions in the evaluation of the sustainability of renewable energy systems. This concludes that LCEA is an effective tool for the design and evaluation of solar energy systems in order to be more sustainable.

  • 59.
    Gong, Mei
    et al.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Energiteknik.
    Wall, Göran
    Chalmers University of Technology, Gothenburg, Sweden.
    Werner, Sven
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Energiteknik.
    Energy and Exergy Analysis of District Heating Systems2012Inngår i: 13th International Symposium on District Heating and Cooling: 3rd of September – 4th of September: Copenhagen, Denmark, 2012, s. 55-60Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The concept of exergy is defined and applied to district heating systems. The influence from different reference state conditions and system boundaries are explained in some detail. The aim is to show the simplicity and value of using the concept of exergy when analyzing district heating processes. The exergy factor is introduced and applied for a number of Swedish and Danish district heating systems. This varies from 14.2% to 22.5% for Swedish district heating systems. The higher the exergy factor, the more the exergy losses in the passive conversion towards space heating. Large losses revealed in an exergy treatment of a process should be seen as a challenge to achieve technical improvements of the system.

  • 60.
    Gong, Mei
    et al.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Rydberglaboratoriet för tillämpad naturvetenskap (RLAS).
    Werner, Sven
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Rydberglaboratoriet för tillämpad naturvetenskap (RLAS).
    Enhanced Biomass CHP plants for district heating systems2019Inngår i: Book of abstracts: 5th International Conference on Smart Energy Systems in Copenhagen, on 10-11 September 2019 / [ed] Henrik Lund, Brian Vad Mathiesen & Poul Alberg Østergaard, Aalborg: Aalborg Universitetsforlag, 2019, s. 239-239Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In Sweden, located in North Europa, more than half of the total heat demand in buildings is met by district heating, but only just above one-third of the heat supply comes from Combined Heat and Power. In this paper, a new enhancement of biomass CHP plant is explored. The modification is that a large absorption heat pump is used for the heat supply to the district heating network. This new solution has so far never been implemented outside China. The benefits will be more electricity from lower condenser pressure and more heat obtained from flue gas condensation. The drawback is that the absorption heat pump will require extracted steam that will decrease electricity generation. In order to estimate the offset between the two benefits and the drawback, a simplified model has been developed to study a typical Swedish biomass CHP plant located in Lund. This enhancement could be part of the transition from third generation district heating (3GDH) to fourth generation district heating system (4GDH) by introducing efficient heat supply plants in current systems with high distribution temperatures. Several cases studied concerning both 3GDH and 4GDH have been compared to reference cases. The results show that the enhancement is a possible way to prepare for future 4GDH. Further investigations are recommended concerning pre-investment in absorption heat pumps as a transition strategy for new CHP plants originally designed for return temperatures of 20-30 ºC.

  • 61.
    Graneskog, Axel
    et al.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Energiteknik.
    Gustafsson, Yngve
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Energiteknik.
    Smart Control: En reaktion på EU:s ekodesignkrav2012Independent thesis Basic level (degree of Bachelor), 15 poäng / 22,5 hpOppgave
    Abstract [en]

    The purpose of this thesis is to assist the Swedish energy company NIBE Energy Systems in their studies of adaptive regulation applicable to electrical water heaters. Due to coming energy classifications of these appliances in the European Union, NIBE Energy Systems needs to use adaptive regulation, called Smart Control, to keep their products in the best possible energy class and remain competitive to the market. By using this Smart Control regulation a 2-3 % improve-ment of efficiency can be credited the system. This is a small number, but heavily needed, since the energy classes are based on the idea that the European Union is provided with electricity from coal condensate power resulting in a 40 % maximum efficiency. Furthermore, doing noth-ing will result in some water heaters not being approved to use on the market from 2015 due to low efficiency. The thesis is made out of three sections; product-/literature studies of products already commercially available using similar principles, data analysis on existing Smart Controlled water heater and recommendations to the company for future development of their own system. Limitations have been made through simplified calculations and thermodynamic assumptions. A conclusion can still be made from the thesis; electrical water heaters using Smart Control saves 10 - 15 % of electrical energy use today in a real world environment. Main sources to this thesis have been data analysis, Internet, brochures and conversations with the mentors.

  • 62.
    Hammar, Mikael
    et al.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Energiteknik.
    Huszág, Máté
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Energiteknik.
    Geotermi i Ungern: Undersökning av Ungerns energisituation inriktat på geotermi samt kapacitetsfaktorn för det största geotermiska värmeverket i Mellaneuropa.2014Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    Hungary’s share of renewable energy in 2010 was 7.9 %, and their renewable energy goal for 2020 is 14.65 %. Geothermal energy is one option that could help to achieve the goal, since Hungary has favorable bedrock, the temperature gradient is above average and thepermeability is high. Today Hungary is importing just over half of its primary energy supply. Because of political conflicts between nations Hungary wants to expand its own production of energy. One of the major investments implemented was to build the largest geothermal heating plant in central Europe, located in Miskolc. This degree theses aims is to raise the capacity factor for this heating plant. To achieve this objective, a survey of how grain dryers and absorption chillers could increase the heat load in the summer has been performed. With grain dryers that only dries wheat, the capacity factor for the geothermal heating plant in Miskolc increased by 2.6 % and by 4.4 % for the absorption chiller. Although surveys have been carried out for a specific case the idea can be implemented in other heating plants.

    Keywords: Capacity factor, geothermal energy, wheat dryers and absorptions chiller.

  • 63.
    Houtkamp, Christofer
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Energiteknik.
    Spillvärmeåtervinning2012Independent thesis Basic level (degree of Bachelor), 15 poäng / 22,5 hpOppgave
    Abstract [en]

    SAPA´s resource of waste heat is the basis for this thesis to investigate the possibility of energy assets in their cooling water and possible uses for it. The energy in the waste water is greater than the current need which has three uses which are (1) heating the factory, (2) converting liquid propane to propane gas and (3) local domestic heating. The average energy load that is available is 1, 7 MW and the average temperature in the cooling water is 41°C. The total energy load at dimensioning out side temperature is approximately 1,6 MW for the three current uses. The temperature is currently too low to be used directly in the existing systems so an upgrade is needed. The district heating has the highest temperature requirements at 100°C in the winter. To reach the relatively high temperatures required a hybrid heat pump proves to be a suitable solution due to a good Coefficient of Performance (COP). The disadvantage is that at the moment hybrid heat pumps have to be tailor made and are therefore very expensive. The investment required to extract the most amount of surplus energy is large due to the expensive tailor made hybrid heat pumps and the high cost of laying underground heat transferring pipes which leads to long pay off times as the value of surplus heat from waste water is low.

  • 64.
    Ibrahim, Munzer
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap.
    Solar Powered Air Conditioning System2019Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
  • 65.
    Jansson, Gösta
    et al.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap.
    Olsson, Robin
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap.
    Utformning av rutinkontroll och drifttagningsprotokoll för solcellsinstallationer: Drifttagning och dokumentation enligt IEC 62446-12016Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [en]

    In line with the Swedish government's initiative and the national potential for expansion ofsolar electricity, many things will happen over the forthcoming years. Like all operationsrelated to the energy sector, there are many sub-processes that can go wrong. One in everyeighth major electrical accident in general occurs due to technical failures that emerged during commissioning.

    For photovoltaic systems there are both Swedish and international standards related to manufacture, testing and maintenance. For this project we have chosen to immerse ourselvesin the IEC 62446 - Grid connection photovoltaic system. IEC 62446-1 is specially designedfor grid-connected photovoltaic systems. The standard is an important part in the assurance ofreliability and includes commissioning, monitoring and documentation.

    This report has been completed together with Solect Power with the purpose of designing aroutine check for commissioning, as well as to compliment Solect Power’s currentdocumentation. The composed documents meets the requirements of IEC 62446 Gridconnected photovoltaic systems - Minimum Requirement, regarding system documentation,commissioning tests and inspection. The report will hopefully facilitate the work of SolectPower so that a smoother workflow can be achieved and mistakes avoided. Compiled documents are presented in the report's appendix.

  • 66.
    Jernstedt, Michael
    et al.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET).
    Bergström, Jarl
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET).
    Analys av energibrunn: Termisk simulering och förslag på återladdning av energibrunn2009Independent thesis Basic level (degree of Bachelor), 15 poäng / 22,5 hpOppgave
    Abstract [en]

    Bedrock heat is a form of renewable energy that plays an important role for our ambition to create a more sustainable society.  Heat that floats beneath the ground can be heat exchanged with a bedrock pump so the energy can be used in our daily life.

    This procedure comes with two big issues. The first problem is that the fluid that’s used to exchange heat under the ground leaks and blends with the ground water. This has been solved and the solution to that problem was a capsule developed by Pemtec AB outside Borås that surrounds the collectors to prevent this to happen. The other problem that hasn’t been solved yet is the cooling effect that freezes the area around the hole, which means in the long run that the temperature inside the hole decreases and the bedrock potential is held back.  This is what our bachelor thesis is about.

    We will simulate a bedrock hole with COMSOL Multiphysics and see what we can do to prevent the temperature inside the hole to decrease. We will for example try to combine solar energy together with bedrock heat to reload the temperature during the summer.  And also see what changes that can do for the usage of bedrock heat.

  • 67.
    Johansson, Alfred
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap.
    Hållbar vattenkraft i Nissan: En förstudie och konsekvensutredning över förutsättningarna för ökade vandringsmöjligheter med nya fiskvägar.2015Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [en]

    The hydropower from Nissan River is of national interest and produces annually 230 GWh from the twelve power stations in the main flow. For modified waters a consideration between the power production and the biological values has to be made. This reports serves as a pre-study for Nissans Vattenråd. It tries to evaluate some of the biological values in the Nissan basin and map the power production in the area. And the size and value of lost power production from new fishways for the twelve stations in the main flow.

    The investment of new fishways is calculated using simplified templates with values from the business. The cost and loss of power due to new fishways are calculated for three cases: fish friendly grates for the power station inlet and bypass for migration. Fish friendly grate and vertical-slot fish passage for migration. The last case is called “scenario” and is a combination with the most suited solution for each station. This includes a restoration of the creek, with maintained power production, for the two stations closest to the ocean.

    The cost for fish friendly grade and bypass for al stations is about 207 mskr and for vertical-slot fish passage 125 mskr. They both result in a loss of power production of 12 GWh/year, corresponding to a value of 3,2 mskr (NordSpot sale price only) annually. Case “scenario” costs 177 mskr and loses additionally 4,2 GWh/year.

    In the overview, large parts of the Nissan runoff has difficulties reaching “god ecological status” which is the goal set for 2021. This goal can be extended to 2027. The main problem is chemical effect of acidification and mercury in the ground, as well as connectivity issue caused by dams and culverts. Salmon and sea trout could earlier migrate to Nissafors and is limited to the lower parts of Nissan to Oskarström. Many of the tributary waters have high biological values. The existing fishways have questioned functionality and delays fish migration today. Before decisions are made about increasing fishways the advice is to do further studies about the breeding grounds. It’s also possible to identify positive cash flows from an increase in fish migration.

  • 68.
    Johansson, Emil
    et al.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET).
    Tegnhammar, Johan
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET).
    Vindkraftens generationsskifte i Halland2012Independent thesis Basic level (degree of Bachelor), 15 poäng / 22,5 hpOppgave
    Abstract [sv]

    Vindkraften expanderar allt mer i Sverige och årsproduktionen ökade till 6,1 TWh år 2011, vilket är en ökning med 74 % jämfört med 2010.

    De nya vindkraftverken som sätts upp idag är oftast av effektstorlekarna 2 000 – 3 000 kW. De som restes tidigare är omkring 200 – 600 kW. I Sverige finns det många vindkraftverk som har varit i drift under en längre tid, och det är flera som passerat sin tekniska livslängd på 20 år. De första vindkraftverken som man reste står ofta på platser med väldigt goda vindförhållanden och har väldigt låga effekter, om man jämför med dagens vindkraftverk. Det börjar därför bli högaktuellt att demontera äldre befintliga verk och resa nya. Detta kallas för vindkraftens generationsskifte, kanske mer känt som repowering.

    Tyskland, Danmark och Nederländerna är länder som redan har bytt ut stora delar av sina vindkraftsflottor. Danmark är världsledande inom repowering och har bytt ut omkring två tredjedelar av sina äldre verk. I många av de projekt som genomförts har en dubblering och ibland till och med en fyrdubblering av energinmängden skett! Genom att resa nya verk blir det oftast färre verk på platsen, samtidigt som mer energi levereras. På så sätt utnyttjas platsen på ett bättre sätt, vindkraftselen blir billigare. Det blir samtidigt enklare att uppnå politiska riktlinjer med mål inom förnybar energi och många anser att landskapsbilden förbättras.

    Detta examensarbete genomfördes i syfte att undersöka möjligheterna och lönsamheten för generationsskiften i Hallands län. För att veta vart de olika vindkraftverken är placerade i Halland genomfördes en kartläggning och identifiering initialt. När verken var kartlagda gjordes projekteringar av nya parker. Det visade sig vara ont om plats att resa de nya verken, eftersom de är högre än de gamla och kräver längre avstånd till bostäder. Därför genomfördes inte enbart projektering av parker där befintliga vindkraftverk står utan även på helt nya områden som idag inte har någon vindkraft. I varje projekt utfördes ekonomiska beräkningar som grundar sig på energiberäkningarna från projekteringen i vindatlasprogrammet WindPRO. Arbetet har också behandlat hur och om ersättning till ägare av befintliga verk och markägare kan ske, samt vad alternativen är för de befintliga vindkraftverken vid ett generationsskifte. Projektgruppen har varit i kontakt med vindkraftsägare och ställt frågor om hur de ställer sig till ett generationsskifte.

    Det främsta resultatet som projektgruppen kommit fram till är att generationsskiften absolut har goda möjligheter till att bli lönsamma. Det kan dock bli problematiskt att få plats med nya vindkraftverk på områden där gamla verk står. Det beror på kommunens regler om avstånd till närboende, och att ett visst antal verk måste resas vid nybyggnation. Ändras dessa regler för generationsskiften, blir möjligheterna väldigt goda. Vad det gäller efterhandsvärde på de gamla verken är slutsatsen, att det går att göra en bra affär genom att sälja sitt verk. Vid skrotning däremot blir intäkterna från försäljning av metallerna för små för att täcka demonteringskostnaden. Generellt sett har vindkraftsägarna en positiv syn till ett generationsskifte.

  • 69.
    Johansson, Ola
    et al.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap.
    Ulverås, Mikael
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap.
    Energieffektivisering genom fastighetsautomation: Grundläggande teori, svensk marknadsöversikt och exempel på verklig installation2016Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [sv]

    För att uppnå Sveriges miljömål begränsad klimatpåverkan behöver åtgärder göras för att minska energianvändningen inom bostads- och servicesektorn, vilken stod för drygt en tredjedel av Sveriges totala energianvändning år 2014. Dålig styrning av värme-, ventilations- och kylsystem är ofta en bidragande orsak till onödigt hög energianvändning inom hushåll och lokalbyggnader. Med hjälp av fastighetsautomation samlas byggnadens tekniska system i ett styr- och övervakningssystem, vilket kan användas för att optimera styrningen. Dock är marknaden för fastighetsautomation dåligt kartlagd och information saknas angående styrsystemens funktioner och användningsområden.

    Rapporten inleds med grundläggande teori för att skapa ökad förståelse för senare delar. Därefter har en undersökning gjorts för ett antal företags styrsystem i syfte att klargöra dess funktioner, användningsområden samt vilken energibesparing styrsystemen ger upphov till. I rapporten beskrivs också tillvägagångssättet för en verklig installation i lokalbyggnaden Kv Slottet 4 och hur energianvändning samt inneklimat har påverkats efter att styrsystemet installerats.

    Resultatet för den svenska marknadsöversikten visar på att fastighetsautomation är etablerat inom byggnadstyperna flerbostadshus och lokalbyggnader medan småhus är en outforskad marknad. Vanliga funktioner som implementeras i styrsystem är drifttidsstyrning, prognosstyrning och effektbegränsning. Undersökningen har visat att fastighetsautomation ger upphov till energibesparingar på i snitt 10 – 40 %. Besparingen varierar dock och beror på flera faktorer som byggnadstyp, geografisk placering och tidigare styrning. Företagen använder också olika metoder för att beräkna energibesparingen varför det är problematiskt att rättvist jämföra besparingen för olika styrsystem. Energibesparingen för de olika byggnadstyperna och installationssystemen har i många fall varit svåra att få tillgång till. Generellt gäller att de företag som tillhandahåller obligatoriskt driftavtal har bättre koll på den besparing som styrsystemet ger upphov till. I examensarbetet har fyra företag kartlagts men för en mer djupgående analys över den svenska marknaden bör fler företag undersökas.

    Efter installationen av det automatiska styrsystemet Ecopilot® på Kv Slottet 4 erhölls en värmeenergibesparing för vald period på upp till 20,6 MWh, vilket motsvarar en procentuell besparing på 53 %. Energibesparingen varierar dock till viss del beroende på vilken beräkningsmetod som används. Byggnadens totala elbesparing uppgick till 6,5 MWh, vilket motsvarar 20 % minskning av elanvändningen för undersökt period. Den beräknade energibesparingen kan inte helt tillskrivas Ecopilot® eftersom ett annat driftfall rådde under jämförd period än det som var precis innan installationen. Via styrsystemets gränssnitt kunde emellertid en sänkt energianvändning härledas till Ecopilot®. Bland annat tack vare effektivare reglering, samkörning av installationssystem, effektivare värmeåtervinning, sänkta ventilationsflöden samt lägre inomhus- och flödestemperaturer. Intervjuer med verksamma personer i byggnaden påvisar att ingen skillnad har märkts på inomhusklimatet före och efter installationen av Ecopilot®, varken med avseende på det termiska klimatet eller på luftkvaliten. För större säkerhet gällande styrsystemets inverkan på inomhusklimatet och energianvändningen bör en längre tidsperiod utvärderas.

  • 70.
    Khalifeh, Ahmad Ali
    et al.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET).
    Ofir, Barak
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET).
    Bedömning av isoleringsgrad på äldre fjärrvärmeledningar: Med hjälp av teoretiska och verkliga värmeförluster2013Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
  • 71. Kjellander, Matilda
    et al.
    Tengvall, Anders
    Design of a small scale hybrid photovoltaic and wind energy system2014Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    Approaching problems with global warming due to the use of fossil fuels, means that new system solutions have to be investigated. This report investigates the possibility to expand an existing photovoltaic system with a wind turbine generator to simplify the expansion of renewable energy sources. Through an extensive literature study and simulation in SIMULINK the result has been developed and tested. It shows that it is possible to connect a wind turbine generator to the same inverter as the PV-modules if no MPPT algorithm for the PV-modules is integrated. To protect the inverter a dump load has to be connected. Because of the complexity a DC-coupled system brings, AC-coupling is advised when expanding PV-modules with a WTG. The optimal wind turbine is considered to be a permanent magnet synchronous generator connected to the AC-bus through a full-effect inverter. The turbine should be chosen according to the intended location based on wind conditions and desired energy production.

  • 72.
    Le, Alex
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET).
    An economic comparison between two district cooling systems in Halmstad2014Independent thesis Advanced level (degree of Master (One Year)), 40 poäng / 60 hpOppgave
    Abstract [en]

    The supply of cooling has increased significantly in recent years, the trend shows that the increase will continue one reason is that the standard of living has increased, but EU has also set a requirement that energy consumption must be better at the same time. With “better” means more efficient and environmentally friendly. District cooling today uses either chillers or naturally available cold sources such as deep sea water, lake water or cold air. Cold air is, of course, only available when the seasons permit it and the cold air is not available when comfort cooling is needed for e.g. offices. The only alternative for areas that do not have a cold water source nearby is to use chillers. The most common chillers today are compressor chillers and absorption chillers.

    The most interesting chiller for the energy and environmental company HEM in Halmstad, is the absorption chiller which is driven by heat. HEM has, during the summer, surplus heat produced in Kristinehed plant which they want to use, they also have an increased inventory of waste during the summer which they get from the municipality of Halland. This heat is, of course, qualified to be used in the making of cold. Absorption chillers is today, however, not as common as compressor chillers which are capable of dealing with most cooling capacities, from small to large, and simultaneously works more or less flawlessly. Most of today’s absorption chillers are of a few hundred kW and upwards while there are no absorption chillers for the smaller effects, they are also very expensive and can have problems with crystallization of the absorbent if the operation is handled incorrectly.

    But it’s also expensive when it comes to piping of district cooling networks depending on where the pipes are desired, for example if it is the middle of town or over a grass field. A fictional project of the area Sannarp is used for a case study in this thesis where one investment alternative was to extend the existing district cooling pipes and another alternative was to invest in absorption chillers to meet the company's cooling demand. The results were obviously much affected by the area's layout and the distance to the first company starting from the existing pipe. The company's cooling demand also affected the results and the first alternatives investment cost could only be competitive with alternative 2 because the distance was just of the right length. If the distance to the company had been shorter, then the cooling demand for the same company has had to be less.

    The conclusion of the project was still in the end that and expansion of the current district cooling network to the company was the most feasible and economically advantageous.

  • 73.
    Le, Alex
    et al.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET).
    Sträng, Alexandra
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET).
    Sveriges utveckling av förnybar elproduktion och dess miljöpåverkan2013Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Denna rapport är en litteratur- och källstudie med syfte att utforska den svenska förnybara elens utveckling. Förnybar energi är idag viktigt i samhället då den genererar den el som vi är i behov av, utan att påverka miljön i lika stor omfattning som tidigare energislag. Målet var att efter genomfört arbete, ha svar på hur Sveriges elmix ser ut och eventuellt kunna svara på hur den kan se ut till nästa generation. Vilka tekniska lösningar som används idag för respektive kraftslag är något som återges i rapporten.

    Alla kraftslag påverkar miljön på något vis. Rapporten beskriver dessa miljöpåverkan med hjälp av livscykelanalyser som pekar på var i produktions- och driftprocessen som den största påverkan sker. Vidare granskar rapporten den svenska elanvändningen och diskussioner har hållits på hur denna kan komma att påverka den framtida elproduktionen. Ett intressant ämne under arbetets gång var, huruvida en storskalig export av el till närliggande länder med hjälp av sjökablar var möjligt för Sverige.

    Studiens slutsats blev att det finns en väldigt stor utbyggnadspotential för ett flertal förnybara kraftslag. Dock bestämmer ett flertal styrmedel utbyggnadstakten. Även politiska beslut har ett stort inflytande för hur mycket förnybar elproduktion som kommer att finnas i framtiden.

  • 74.
    Lennermo, Gunnar
    et al.
    Mälardalen University, Västerås, Sweden & Energianalys AB, Alingsås, Sweden.
    Lauenburg, Patrick
    Department of Energy Sciences, Lund University, Lund, Sweden.
    Werner, Sven
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Rydberglaboratoriet för tillämpad naturvetenskap (RLAS).
    Control of decentralised solar district heating2019Inngår i: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 179, s. 307-315Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The purpose of decentralised solar district heating plants is to feed solar heat directly into district heatingnetworks. This decentralised heat supply has to consider two major output conditions: a stable required feed-insupply temperature and a feed-in heat power equal to the heat output from the solar collectors. However, manyinstallations cannot achieve the second output condition, since severe oscillations appear in the feed-in heatpower. This problem can be solved by two different control concepts with either temperature- or flow-control.Detailed measurements from two reference plants are provided for these two different control concepts. Onemain conclusion is that a robust control system is characterized by the ability to provide required flows andtemperatures. The major difference between robust and less robust control is that the supply temperatures and/or flows do not fluctuate even if the input conditions are unfavourable. © 2019 Elsevier Ltd. All rights reserved.

  • 75.
    Lerin, Tommy
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET).
    Förutsättningar och Avsättningar för Biogas för Gröna Vessigebro: Version 1.02014Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [en]

    The community Vessigebro, in Falkenberg and its surrounding areas housing one percent of all dairy cattle and two percent of all pigs in Sweden. This means that there is a large amount of manure as a basis for producing biogas in the area. A number of farmers have therefore formed a cooperative named Vessigebro biogas and started the project Green Vessigebro, with the goal of creating the conditions for a more profitable and more sustainable agriculture production.

    The study deals with the conditions and sale opportunities of the feasibility study Green Vessigebro. The study has looked at the work that was previously carried out for the biogas that could be produced on the farms in Vessigebro, The main pipeline for natural gas on the Swedish west coast and its operators, the Swedish Competition Act , Electricity Act , Natural Gas Act, the District Heating Act , Sustainability Act , previously proposed measures, municipality interest in biogas from Vessigebro , possible collaborations, possible sale opportunities and perform calculations with data from the municipality Ljungby for a suggested transportation of biogas between Vessigebro and Ljungby.

    The study shows that there are several interesting sale opportunities for biogas from Vessigebro. The production and use of biogas in Sweden is increasing and the trend seems set to continue. Six gas retailers can buy gas, which EON is the most established around Vessigebro with a distribution network. EON: s distribution network runs only a few kilometers from the planned upgrading plant , in Vessigebro. An already built upgrading facility is one mil from Vessigebro. Swedegas is the only main pipeline network owner with storing and balancing responsibility on the main line that is closer than EON distribution network. A number of suppliers and industries have shown interest in purchasing the biogas and the interest from potential buyers are likely to increase when the biogas production starts. A collaboration with, for example, "Arena Bioenergy Halland" increases business intelligence and can provide an increased influence with policy proposals. The use of gas and the interest is too low for the moment for tractors, boats, trains, buses and taxis to be a possible outlet specifically for Vessigebro biogas.

    The conditions make it interesting for Vessigebro biogas to look at five different options for sale opportunities of the biogas. Three options are based on a pipeline to either the pipeline, owned by Swedegas or EON distribution line alternatively a pipeline to EON upgrading facility. One possibility is to replace vehicles that run on fossil fuels with gas-powered vehicles providing a local use and purpose and the aims of the project Green Vessigebro. The calculations made by the study with different conditions shows that a very interesting and possible sale opportunity is a transportation of biogas between Vessigebro and Ljungby.

    The conclusion from the study shows that conditions and sale opportunities are good for the planned biogas production of Green Vessigebro to become reality.

  • 76.
    Leurent, Martin
    et al.
    Université Paris-Saclay, Gif-sur-Yvette, France.
    Da Costa, Pascal
    Université Paris-Saclay, Gif-sur-Yvette, France.
    Jasserand, Frédéric
    Université Paris-Saclay, Gif-sur-Yvette, France.
    Rämä, Miika
    VTT Technical Research Centre of Finland, VTT, Espoo, Finland.
    Persson, Urban
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Rydberglaboratoriet för tillämpad naturvetenskap (RLAS).
    Cost and climate savings through nuclear district heating in a French urban area2018Inngår i: Energy Policy, ISSN 0301-4215, E-ISSN 1873-6777, Vol. 115, s. 616-630Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper compares the socioeconomic potential of heating systems that could be developed in the Lyon urban area (France). The district heating (DH) systems investigated in this paper use low-carbon heat sources: large-scale heat pumps (LSHP) or nuclear combined heat and power plants (NCHP). They are compared with electric boilers and central gas boilers in terms of greenhouse gas emissions and heating costs. The heating systems are dimensioned to supply the projected 2030 heat loads for two different land surface areas (extensive and compact). The key input data is the empirical residential and tertiary heat demand per square kilometre for 2015, extrapolated to 2030 to account for the potential decrease in the heat demand (energy-efficient buildings). Given the assumptions made in this paper, the heating system that obtains the best balance between CO2 emissions and heating cost relies on an NCHP located about 30 km from Lyon. Cases in which the heat has to be transported over longer distances are considered, hence providing insights for metropolitan areas with similar size and density as the Lyon area. Implications for stakeholders and policy makers are discussed, so that to optimize future French energy systems through the most efficient use of available technologies. © 2018 Elsevier Ltd. All rights reserved.

  • 77.
    Leurent, Martin
    et al.
    Université Paris-Saclay, Gif-sur-Yvette, France.
    Da Costa, Pascal
    Université Paris-Saclay, Gif-sur-Yvette, France.
    Rämä, Miika
    VTT Technical Research Centre of Finland, VTT, Espoo, Finland.
    Persson, Urban
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Rydberglaboratoriet för tillämpad naturvetenskap (RLAS).
    Jasserand, Frédéric
    Université Paris-Saclay, Gif-sur-Yvette, France.
    Cost-benefit analysis of district heating systems using heat from nuclear plants in seven European countries2018Inngår i: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 149, s. 454-472Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper aims to evaluate and compare the potential cost savings and greenhouse gas (GHG) reduction of district heating (DH) systems using heat from nuclear combined heat and power plants (NCHP) in Europe. Fifteen DH + NCHP systems, spread throughout seven countries, are studied. The selection was made in collaboration with ‘the Ad-Hoc Expert Group on the Role and Economics of Nuclear Cogenerationin a Low Carbon Energy Future’ from the Organisation for Economic Co-operation and Development. Firstly, the linear heat density of the modelled DH networks was determined, including locations with poorly developed DH networks. A large potential for extending DH networks was identified for France and the United Kingdom despite the expected decrease in the heat demand due to building renovation. Secondly, the costs and GHG emissions of DH + NCHP systems were evaluated via a cost benefit analysis. It concluded that 7 of the 15 projects would be cost-effective if 25% of the total urban heat demand was supplied. Implementing NCHP-based systems would reduce GHG emissions by approximately 10 Mt eCO2/a. Four additional DH + NCHP systems could become competitive if a larger share of the total demand was supplied. Finally, a sensitivity analysis was performed to evaluate the uncertainty affecting the key parameters. © 2018 Elsevier Ltd

  • 78. Lind, Johan
    Indata till energiberäkningar för nybyggda småhus: En jämförelse med Sveby 122017Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
  • 79.
    Lindgren, Matilda
    et al.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap.
    Mattsson, Pierre
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap.
    Det framtida svenska elsystemet & lönsamheten för produktionsplanering2018Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [sv]

    På uppdrag av Skövde Värmeverk undersöker detta examensarbete hur det svenska framtida kraftsystemet kan vara utformat genom en jämförande litteraturstudie. Det utförs också en ekonomisk utvärdering av att undvika balansavgifter med hjälp av produktionsplanering av elproduktionen för energibolagets två kraftvärmeverk.

    Den jämförande litteraturstudien omfattade relevanta scenariostudier, utredningar och prognoser från myndigheter och organisationer. Även litteratur om det danska och tyska kraftsystemet undersöktes för att göra en jämförelse mellan ländernas elförsörjning.

    Två scenarier togs fram för kostnadsbesparing med en ökad prisvolatilitet i förhållande till referensåret 2017. Ett scenario med hjälp av lägre genomsnittspriser och ett med högre genomsnittspriser. Priserna är prognostiserade årsgenomsnittspriser som har gjorts om till spotpriser på timbasis i enlighet med den variation som fanns året 2017, dock med en ökad volatilitet på 1 procentenhet per år från referensårets priser.

    Kostnadsbesparingen baseras på en obalans om 3MW vid alla tillfällen som spotpris och nedregleringspris har en differens. Orsaken till den schablonmässiga beräkningen är avsaknaden av den inrapporterade produktionsplanen till systemansvarig aktör och därmed den verkliga obalansen som uppstod året 2017. I detta fall är det endast nedreglering av elproduktion som utvärderats och en möjlig bränslebesparing togs därför fram. I detta fall kan alternativ dyrare värmeproduktion regleras ned om 3MW elproduktion ersätter annan värmeproduktion.

    Resultatet tyder på ett svenskt kraftsystem utan kärnkraft efter åren 2040 - 2050 och en fortsatt investering i det interna nätet samt i utlandsförbindelser. Ökningen av intermittent kraft, exempelvis vindkraft, väntas fortsätta och det svenska kraftsystemet har på grund av vattenkraften goda förutsättningar att hantera volatil produktion och de prisvariationer som framträder mer i system utan samma flexibilitet. Kring frågan om likheter mellan Sveriges, Danmarks och Tysklands kraftsystem är det förutsättningarna att ta sig an utmaningarna som skiljer länderna emellan. Kostnadsbesparingen för produktionsplanering av kraftvärmeverken visar ett positivt resultat som ökar vid en möjlig bränslebesparing. 

  • 80.
    Lund, Henrik
    et al.
    Ålborgs universitet, Ålborg, Danmark.
    Werner, Sven
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Energiteknik.
    Wiltshire, Robin
    Building Research Establishment, Watford, UK.
    Svendsen, Svend
    Danmarks Tekniska Universitet - DTU, Lyngby, Danmark.
    Thorsen, Jan Eric
    Danfoss, Nordborg, Danmark.
    Hvelplund, Frede
    Ålborgs Universitet, Ålborg, Danmark.
    Vad Mathiesen, Brian
    Ålborgs universitet, Köpenhamn, Danmark.
    4th Generation District Heating (4GDH): Integrating smart thermal grids into future sustainable energy systems2014Inngår i: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 68, s. 1-11Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper defines the concept of 4th Generation District Heating (4GDH) including the relations to District Cooling and the concepts of smart energy and smart thermal grids. The motive is to identify the future challenges of reaching a future renewable non-fossil heat supply as part of the implementation of overall sustainable energy systems. The basic assumption is that district heating and cooling has an important role to play in future sustainable energy systems – including 100 percent renewable energy systems – but the present generation of district heating and cooling technologies will have to be developed further into a new generation in order to play such a role. Unlike the first three generations, the development of 4GDH involves meeting the challenge of more energy efficient buildings as well as being an integrated part of the operation of smart energy systems, i.e. integrated smart electricity, gas and thermal grids. © 2014 Elsevier Ltd.

  • 81.
    Lund, Henrik
    et al.
    Aalborg University, Aalborg, Denmark.
    Østergaard, Poul Alberg
    Aalborg University, Aalborg, Denmark.
    Chang, Miguel
    Aalborg University, Aalborg, Denmark.
    Werner, Sven
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Rydberglaboratoriet för tillämpad naturvetenskap (RLAS).
    Svendsen, Svend
    DTU, Denmark Technical University, Lyngby, Denmark.
    Sorknæs, Peter
    Aalborg University, Aalborg, Denmark.
    Thorsen, Jan Eric
    Danfoss Heating Segment, Nordborg, Denmark.
    Hvelplund, Frede
    Aalborg University, Aalborg, Denmark.
    Mortensen, Bent Ole Gram
    University of Southern Denmark, Odense, Denmark.
    Mathiesen, Brian Vad
    Aalborg University, Copenhagen, Denmark.
    Bojesen, Carsten
    Aalborg University, Aalborg, Denmark.
    Duic, Neven
    University of Zagreb, Zagreb, Croatia.
    Zhang, Xiliang
    Tsinghua University, Beijing, China.
    Möller, Bernd
    Europa-Universität Flensburg, Flensburg, Germany.
    The status of 4th generation district heating: Research and results2018Inngår i: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 164, s. 147-159Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This review article presents a description of contemporary developments and findings related to the different elements needed in future 4th generation district heating systems (4GDH). Unlike the first three generations of district heating, the development of 4GDH involves meeting the challenge of more energy efficient buildings as well as the integration of district heating into a future smart energy system based on renewable energy sources. Following a review of recent 4GDH research, the article quantifies the costs and benefits of 4GDH in future sustainable energy systems. Costs involve an upgrade of heating systems and of the operation of the distribution grids, while benefits are lower grid losses, a better utilization of low-temperature heat sources and improved efficiency in the production compared to previous district heating systems. It is quantified how benefits exceed costs by a safe margin with the benefits of systems integration being the most important. © 2018 Elsevier Ltd

  • 82.
    Lund, Rasmus
    et al.
    Department of Development and Planning, Aalborg University, Copenhagen, Denmark.
    Persson, Urban
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Energivetenskap.
    Mapping of potential heat sources for heat pumps for district heating in Denmark2016Inngår i: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 110, s. 129-138Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The ambitious policy in Denmark on having a 100% renewable energy supply in 2050 requires radical changes to the energy systems to avoid an extensive and unsustainable use of biomass resources. Currently, wind power is being expanded and the increasing supply of electricity is slowly pushing the CHP (combined heat and power) plants out of operation, reducing the energy efficiency of the DH (district heating) supply. Here, large heat pumps for district heating is a frequently mentioned solution as a flexible demand for electricity and an energy efficient heat producer. The idea is to make heat pump use a low temperature waste or ambient heat source, but it has so far been very unclear which heat sources are actually available for this purpose.

    In this study eight categories of heat sources are analysed for the case of Denmark and included in a detailed spatial analysis where the identified heat sources are put in relation to the district heating areas and the corresponding demands. The analysis shows that potential heat sources are present near almost all district heating areas and that sea water most likely will have to play a substantial role as a heat source in future energy systems in Denmark.

  • 83.
    Lygnerud, Kristina
    et al.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Rydberglaboratoriet för tillämpad naturvetenskap (RLAS).
    Werner, Sven
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Rydberglaboratoriet för tillämpad naturvetenskap (RLAS).
    Risk assessment of industrial excess heat recovery in district heating systems2018Inngår i: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 151, s. 430-441Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The recovery of industrial excess heat for use in district heating systems can be characterised by great political interest, high potential, low utilisation and often high profitability. These characteristics reveal that barriers are present for its greater utilisation. One identified barrier is the risk that industries with excess heat can terminate their activities, resulting in the loss of heat recovery. Excess heat recovery investments are therefore sometimes rejected, despite them being viable investments. The risk of termination of industrial activities has been assessed by a study of 107 excess heat recoveries in Sweden. The analysis verified that terminated industrial activities are one of two major explanations for terminated heat delivery. The other major reason is substitution by another heat supply. These two explanations correspond to approximately 6% of all annual average heat recoveries. The identified risk factors are small annual heat recovery and the use of heat pumps when low-temperature heat was recovered. The main conclusion is that a small proportion of industrial heat recovery has been lost in Sweden because of terminated industrial activities. The risk premium of losing industrial heat recovery for this specific reason should be considered to be lower than often presumed in feasibility studies. © 2018 Elsevier Ltd

  • 84.
    Lygnerud, Kristina
    et al.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Energivetenskap.
    Werner, Sven
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Energivetenskap.
    Risk of industrial heat recovery in district heating systems2016Inngår i: Proceedings of the 15th International Symposium on District Heating and Cooling: September 4th - 7th, 2016, Seoul, South Korea / [ed] Rolf Ulseth & Kyung Min Kim, 2016, s. 144-147Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Industrial heat recovery can be used in district heating systems. It is a possibility to make use of heat that is otherwise lost. Increased usage of industrial heat recovery reduces the need for fuel combustion lowering green-house gas (GHG) emissions, such as CO2. Industrial companies can, however, move or close down industrial activities. This is apprehended as a risk and lowers the interest of district heating companies to invest in industrial heat recovery.

    In Swedish district heating systems, industrial heat recoveries have been undertaken since 1974. Today, the heat recovery is active in about seventy systems. This leads to the question of how risky it is, for district heating companies, to engage in industrial heat recovery.

    Over forty years of operation statistics have been collected and analyzed in order to estimate the risk of industrial heat recovery to district heating companies. Key results show that the risk is not linked to different industrial branches. Recommendations include suggestions to management on how to consider risk and consequence when assessing potential industrial heat recovery investments.

  • 85.
    Lygnerud, Kristina
    et al.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Rydberglaboratoriet för tillämpad naturvetenskap (RLAS).
    Werner, Sven
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Rydberglaboratoriet för tillämpad naturvetenskap (RLAS).
    Risk of industrial heat recovery in district heating systems2017Inngår i: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 116, s. 152-157Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Industrial heat recovery can be used in district heating systems. It is a possibility to make use of heat that is otherwise lost. Increased usage of industrial heat recovery reduces the need for fuel combustion lowering green-house gas (GHG) emissions, such as CO2. Industrial companies can, however, move or close down industrial activities. This is apprehended as a risk and lowers the interest of district heating companies to invest in industrial heat recovery.

    In Swedish district heating systems, industrial heat recoveries have been undertaken since 1974. Today, the heat recovery is active in about seventy systems. This leads to the question of how risky it is, for district heating companies, to engage in industrial heat recovery.

    Over forty years of operation statistics have been collected and analyzed in order to estimate the risk of industrial heat recovery to district heating companies. Key results show that the risk is not linked to different industrial branches. Recommendations include suggestions to management on how to consider risk and consequence when assessing potential industrial heat recovery investments. © 2017 The Authors. Published by Elsevier Ltd.

  • 86.
    Mensah, Ebenezer Blay
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap.
    Energikartläggning på Höstro servicehus: En energianalys i syfte att effektivisera energianvändningen.2015Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
  • 87.
    Mondlane, Victor
    et al.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap.
    Delvert, David
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap.
    Framtidssäker Utveckling i Miljonprogrammet: Smarta val för fortsatta energiförbättringar2016Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Energianvändningen i byggnader från det Svenska miljonprogrammet från mitten av 60-talet ärrelativt hög jämfört med moderna motsvarigheter och eventuella renoveringsprojekt kompliceras avatt flera olika energi- och byggtekniska lösningar spelar in och interagerar med varandra på sätt sominte alltid är uppenbara. Idag görs få åtgärder med specifik avsikt att minska en byggnadsenergianvändning och detta beror mycket på att akuta åtgärder prioriteras på grund avbyggnadernas skick och att byggföretagen, som är experter inom de byggtekniska områdena, intesjälva ger förslag på fler meningsfulla energirenoveringar i samband med de som brukar utföras.Många moderna tekniker så som solceller på tak, värmeåtervinning av ventilationsluft, stambyte ochoptimering av belysning, kan inte i denna process ses som en enskild del utan påverkan på de andradelarna. Nästan allt påverkar det slutgiltiga resultatet och det krävs kunskap och en vilja att se längreän till bara akuta och nödvändigaste som behöver åtgärdas, för att kunna projektera en renoveringdär inget står i vägen för det önskade resultatet. Genom att måla upp en tydlig bild av sina byggnaderi ett tidigt skede och etablera hur de önskas se ut i framtiden kan hela beslutskedjan lättare förståvissa val och varför specifika förbättringar bör göras.Övergripande står värmeförluster för majoriteten av energiförlusterna i miljonprogrammetsbyggnader och det är i den kategorin som de första omfattande åtgärderna bör tas, med tätning ochöversikt av klimatskalet som ett bra första steg. I samband med detta kan flertalet andra åtgärder tassom också berörs av renoveringarnas ingrepp på fasaden. Dessa synergier tillsammans med ett ökatframtidstänk och ansvarstagande är det övergripande temat i denna publikation.

  • 88.
    Mårtensson, Daniel
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap.
    Energieffektivisering bland företag: En undersökning om energikartläggningar och dess utsträckning i Halland2016Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [en]

    The master’s dissertation has been made as an examination of the course Energy engineer atUniversity of Halmstad. Focus of the course is on renewable energy and the essay is aboutenergy audit, if it’s possible to complete in different industries.The work started with gathering of information about laws and support. After that, threecompanies got chosen to be interviewed about depth study on what measures the companyhave made on their energy audit.Besides these three companies there have also been made a survey within the master’sdissertation. The survey has been sent out to 100 companies which 45 have answered on it.The survey contains various questions about energy audit and contribution. The master’sdissertation also contains a theoretical part which gives a picture of what kind of differentmeasures can be made to give examples.On the three companies which the master’s dissertation have been made, a depth study aboutthe companies showed that the companies have completed different measures, dependent onwhat kind of operation the companies is engaged in. Since the companies is in differentindustries the energy audit shows that it can be made in different operations. The companieshave all made energy savings through measures such as, controlling of ventilation,replacement of the lightning and other non-technical measures. Two of the companies haveenergy utilization which correspond 100 MWh on each company over various amount years.On the third companies there have also been made energy utilization but they have alsoexpanded their operation so it’s hard to see how much energy utilization which have beendone. The survey has been executed to research why companies have or haven’t made anenergy audit. The survey has issues about if companies will perform an energy audit if theyget information about the subject. One question explores which measures are the mostcommon and popular to be made on an energy audit. The survey shows that the information isinadequate when it comes to sources of information, but it can be improve by evolving theinformation sources that are least used. Survey have also issues about why companies haven’tcompleted an energy audit, which have given the answers that it is because of it’s not thecompanies highest priority, lack of time and the information is inadequate about energy audit.The most popular measures which have been made according to the survey is lightning,ventilation, heating system and heat recovery. Reason for lightning became the most popularis because it is the cheapest measures.The master’s dissertation also compared the results from the three companies interviewedwith the survey and have come to the conclusion that both have the same measure as the mostpopular.Key words: Energy audit, energy usage, energy utilization

  • 89.
    Möllerström, Erik
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Rydberglaboratoriet för tillämpad naturvetenskap (RLAS). Uppsala University, Uppsala, Sweden.
    Noise, eigenfrequencies and turbulence behavior of a 200 kW H-rotor vertical axis wind turbine2017Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Vertical-axis wind turbines (VAWTs) have with time been outrivaled by the today more common and economically feasible horizontal-axis wind turbines (HAWTs). However, VAWTs have several advantages which still make them interesting, for example, the VAWTs can have the drive train at ground level and it has been argued that they have lower noise emission. Other proposed advantages are suitability for both up-scaling and floating offshore platforms.

    The work within this thesis is made in collaboration between Halmstad University and Uppsala University. A 200-kW semi-guy-wired VAWT H-rotor, owned by Uppsala University but situated in Falkenberg close to Halmstad, has been the main subject of the research although most results can be generalized to suit a typical H-rotor.

    This thesis has three main topics regarding VAWTs: (1) how the wind energy extraction is influenced by turbulence, (2) aerodynamical noise generation and (3) eigenfrequencies of the semi-guy-wired tower.

    The influence from turbulence on the wind energy extraction is studied by evaluating logged operational data and examining how the power curve and the tip-speed ratio for maximum Cp is impacted by turbulence. The work has showed that the T1-turbine has a good ability to extract wind energy at turbulent conditions, indicating an advantage in energy extraction at turbulent sites for VAWTs compared to HAWTs.The noise characteristics are studied experimentally, and models of the two most likely aerodynamic noise mechanisms are applied. Here, inflow-turbulence noise is deemed as the prevailing noise source rather than turbulent-boundary-layer trailing-edge noise (TBL-TE) which is the most important noise mechanism for HAWTs. The overall noise emission has also been measured and proven low compared to similar sized HAWTs.

    The eigenfrequencies of a semi-guy-wired tower are also studied. Analytical expressions describing the first-mode eigenfrequency of both tower and guy wire has been derived and verified by experiments and simulations.

  • 90.
    Möllerström, Erik
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Energiteknik.
    Vertical Axis Wind Turbines: Tower Dynamics and Noise2015Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Vertical axis wind turbines (VAWTs) have with time been outrivaled by the today common and economically feasible horizontal axis wind turbines (HAWTs). However, VAWTs have several advantages such as the possibility to put the drive train at ground level, lower noise emissions and better scaling behavior which still make them interesting for research.

    The work within this thesis is made in collaboration between the Department of Construction and Energy Engineering at Halmstad University and the Division for Electricity at Uppsala University. A 200 kW VAWT owned by the latter and situated close to Falkenberg in the southwest of Sweden has been the main subject of the research even if most learnings has been generalized to fit a typical vertical turbine. This particular turbine has a wooden tower which is semi-guy-wired, i.e. the tower is both firmly attached to the ground and supported by guy-wires.

    This thesis has two main topics both regarding VAWTs: eigenfrequency of the tower and the noise generated from the turbine. The eigenfrequency of a semi-guy-wired tower is studied and an analytical expression describing this is produced and verified by experiments and simulations. The eigenfrequency of the wire itself and how it is affected by wind load are also studied.  The noise characteristics of VAWTs have been investigated, both theoretically and by noise measurement campaigns. Both noise emission and frequency distribution of VAWTs has been studied.

    The work has resulted in analytical expressions for tower and wire eigenfrequency of a semi-guy-wired tower as well as recommendations for designing future towers for VAWTs. The noise emission of VAWTs has been studied and proven low compared to HAWTs. The noise frequency distribution of the 200 kW VAWT differs significantly from that of a similar size HAWTs with for example lower levels for frequencies below 3000 Hz.

  • 91.
    Möllerström, Erik
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Rydberglaboratoriet för tillämpad naturvetenskap (RLAS).
    Whatever became of the vertical axis wind turbine?2019Inngår i: Modern power systems, ISSN 0260-7840, Vol. 39, nr 4, s. 12-16Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
    Abstract [en]

    Alongside the story of today’s commercially successful, propeller-type, horizontal axis wind turbine (HAWT), there is the lesser known story of the vertical axis wind turbine (VAWT). Once seen as a competitor in setting the standard for wind turbine design, utility-scale VAWTs have become a more and more unusual sight. However, utility-scale VAWT prototypes do from time to time still appear as attempts are made to establish vertical axis technology in a market totally dominated by horizontal axis machines. This is a retrospective survey of utility-scale VAWT projects, with turbines of 100 kW or more.

  • 92.
    Möllerström, Erik
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Rydberglaboratoriet för tillämpad naturvetenskap (RLAS).
    Wind Turbines from the Swedish Wind Energy Program and the Subsequent Commercialization Attempts – A Historical Review2019Inngår i: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 12, nr 4, artikkel-id 690Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    This paper summarizes wind turbines of Swedish origin, 50 kW and above. Both the large governmental-funded prototypes from the early 1980s and following attempts to build commercial turbines are covered. After the 1973 oil crisis, a development program for wind turbine technology was initiated in Sweden, culminating in the early 1980s with the 2 and 3-MW machines at Maglarp and Näsudden. However, government interest declined, and Sweden soon lost its position as one of the leading countries regarding wind turbine development. Nevertheless, several attempts to build commercial wind turbines in Sweden were made in the following decades. Most attempts have, like the earlier prototypes, used a two-bladed rotor, which has become synonymous with the Swedish wind turbine development line. The current ongoing Swedish endeavors primarily focus on the niche-concept of vertical axis wind turbines (VAWTs), which is a demonstration of how far from the broad commercial market of Sweden has moved. Thus far, none of the Swedish attempts have been commercially successful, and unlike countries like Denmark or Germany, Sweden currently has no large wind turbine producer. Suggested reasons include early government interventions focusing on two-bladed prototypes and political disinterest, with wind power grants cut in half by 1985, and the domestic industry not being favored in government policies for deploying wind power.

  • 93.
    Möllerström, Erik
    et al.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Energiteknik. Division for Electricity, Department of Engineering Sciences, Uppsala University, Uppsala, Sweden.
    Bolin, Karl
    Marcus Wallenberg Laboratory, Department of Aeronautical and Vehicle Engineering, KTH Royal Institute of Technology, Stockholm, Sweden.
    Ottermo, Fredric
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Energiteknik.
    Bååth, L.B.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Maskinteknisk produktframtagning (MTEK).
    Hylander, Jonny
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Energiteknik.
    Noise directivity from a vertical axis wind turbine2015Inngår i: Proceedings of the 6th International Conference on Wind Turbine Noise 2015, New Brighton: INCE/Europe , 2015Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    The directivity of wind turbine noise is of widespread interest and has received attention over an extended period. The reason for this is partly that noise optimization procedures can be implemented in order to increase the efficiency of the power output. Although directivity of horizontal axis wind turbines (HAWTs) are well understood, the directivity pattern around vertical axis wind turbines (VAWTs) are less well investigated.This paper presents measurements of directivity on a 200 kW VAWT, a so called H-rotor, with variable speed and a tower height of 40 m. The turbine, which is situated in a flat agricultural landscape close to Falkenberg at the Swedish west coast, is one of the world’s largest today operational VAWTs. Experimental results as well as a theoretical model based on the turbulent-boundary-layer trailing-edge (TBL-TE) noise suggest higher noise levels upwind of the rotor and the lowest noise levels in the perpendicular directions. Moreover, modulation analysis of the measurements indicates the presence of modulations but the results are inconclusive.

  • 94.
    Möllerström, Erik
    et al.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Energiteknik. Uppsala University, Uppsala, Sweden.
    Eriksson, Sandra
    Uppsala University, Uppsala, Sweden.
    Goude, Anders
    Uppsala University, Uppsala, Sweden.
    Ottermo, Fredric
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Energiteknik.
    Hylander, Jonny
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Energiteknik.
    Turbulence influence on optimum tip speed ratio for a 200 kW vertical axis wind turbine2016Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 753, artikkel-id 032048Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The influence of turbulence intensity (TI) on the tip speed ratio for maximum power coefficient, here called λCp-max, is studied for a 200 kW VAWT H-rotor using logged data from a 14 month period with the H-rotor operating in wind speeds up to 9 m/s. The TI - λCp-max relation is examined by dividing 10 min mean values in different turbulence intensity ranges and producing multiple CP(λ) curves. A clear positive relation between TI and λCp-max is shown and is further strengthened as possible secondary effects are examined and deemed non-essential. The established relation makes it possible to tune the control strategy to enhance the total efficiency of the turbine.

  • 95.
    Möllerström, Erik
    et al.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Rydberglaboratoriet för tillämpad naturvetenskap (RLAS).
    Gipe, Paul
    Wind-works.org, Bakersfield, CA, USA.
    Beurskens, Jos
    SET Analysis, Schagen, the Netherlands.
    Ottermo, Fredric
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Rydberglaboratoriet för tillämpad naturvetenskap (RLAS).
    A historical review of vertical axis wind turbines rated 100 kW and above2019Inngår i: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 105, s. 1-13Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    This paper summarizes and introduces all vertical axis wind turbine (VAWT) projects where 100 kW or larger turbines have been installed. The basis for the review is both existing literature and personal correspondence with people once involved in the different developments. By citing the most relevant work for each project, the paper will also work as an information hub, making information on these projects more accessible.

    Since the 1970s, there have been several VAWT projects with installed turbines of significant size, either as attempts to commercialize VAWTs, or as university led research projects, or as a combination of the two. Most have involved Darrieus turbines built in North America during the 1980s. However, H-rotors, which have always been a favored concept in Europe, have seen a revival during the 2010s.

    The reason VAWTs have never fully challenged the success of the horizontal axis wind turbine (HAWT) is too broad a question to answer here. However, the reasons some VAWT projects have failed are addressed in this paper. Besides the fact that many of the prototypes had terminal failures, most of the installed medium or large-scale VAWTs have to some extent had problems with metal fatigue and durability. Additionally, a lack of long-term interest from governmental or private funders, as well as the introduction of reliable HAWTs, was a recurring theme from those involved in VAWT development, regarding the reason VAWTs so far have failed to succeed. © 2018 The Author(s)

  • 96.
    Möllerström, Erik
    et al.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Energiteknik. Uppsala University, Uppsala, Sweden.
    Larsson, Sebastian
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET).
    Ottermo, Fredric
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Energiteknik.
    Hylander, Jonny
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Energiteknik.
    Bååth, Lars
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Maskinteknisk produktframtagning (MTEK).
    Noise Propagation from a Vertical Axis Wind Turbine2014Inngår i: Proceedings of 43rd International Congress on Noise Control Engineering: Internoise 2014 / [ed] John Davy, Charles Don, Terry McMinn, Liz Dowsett, Norm Broner & Marion Burgess, Brisbane, QLD: Australian Acoustical Society , 2014Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Initial noise measurements were performed on a 200kW vertical axis wind turbine (VAWT) and results were compared to that of a Vestas V27, a similar size horizontal axis wind turbine (HAWT). Multiple recording units were placed in line downwind of the turbine to investigate noise propagation. The frequency distribution of the noise were analyzed indicating that the VAWT has lower relative levels for frequencies under 3000 Hz, especially within 600-1200 Hz. Furthermore, VAWT noise seems to occur more around the same frequencies as the natural background noise, increasing masking probability. Results from propagation measurements seemed to indicate that noise declines more rapidly with distance for the VAWT then for the reference HAWT, possibly explained by the lower levels at low frequencies. Further investigation is needed to establish these differences and the 200 kW VAWT creates an opportunity doing so utilizing arguably the largest operational VAWT existing today.

  • 97.
    Möllerström, Erik
    et al.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Rydberglaboratoriet för tillämpad naturvetenskap (RLAS).
    Ottermo, Fredric
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Rydberglaboratoriet för tillämpad naturvetenskap (RLAS).
    Calculational model for first-mode eigenfrequency of a semi-guy-wired vertical-axis wind turbine tower2019Inngår i: Wind Engineering: The International Journal of Wind Power, ISSN 0309-524X, E-ISSN 2048-402XArtikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A simple model for accounting for tower mass when estimating the first-mode eigenfrequency of a semi-guy-wired tower has been derived. This extends previous work where an analytical model of the semi-guy-wired tower of a 200-kW vertical-axis wind turbine was developed. The model was primarily used to estimate the eigenfrequencies as a result of adding guy wires to a free-standing tower (thus creating a semi-guy-wired setup). However, a weakness with the model was that the tower mass was accounted for in a rough way that essentially ignored the guy wires, which gave a larger-than-necessary error. In this work, an effective top mass, that takes into account the tower mass and the constraints from the guy wires, is derived to achieve a higher accuracy when estimating the first-mode eigenfrequency. This, together with the earlier models, gives a more complete method to estimate the eigenfrequencies for a semi-guy-wired wind turbine. © The Author(s) 2019.

  • 98.
    Möllerström, Erik
    et al.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Rydberglaboratoriet för tillämpad naturvetenskap (RLAS).
    Ottermo, Fredric
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Rydberglaboratoriet för tillämpad naturvetenskap (RLAS).
    Comparison of inflow-turbulence and trailing-edge noise models with measurements of a 200-kW vertical axis wind turbine2019Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 1222, artikkel-id 012028Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Models of inflow-turbulence noise and turbulent-boundary-layer trailing-edge noise are compared to earlier measurements of a 200-kW vertical axis wind turbine so that conclusions regarding the origin of the aerodynamic noise can be drawn. The measurement campaigns, which aimed at establishing the noise emission value and locating the aerodynamic noise sources with a microphone array, are here both compared to further modified versions of the trailing-edge and inflow-turbulence models respectively. Unlike the case for horizontal axis wind turbine, inflow-turbulence noise is deemed as the prevailing noise mechanism. Reducing the self-induced turbulence could then be an effective way of lowering the noise levels for vertical axis wind turbines. Also, looking at the directivity of the inflow-turbulence noise model which indicate most noise in the cross-wind directions, a deviation from the standard downwind measurement position for measuring noise emission is suggested for the VAWT case.

  • 99.
    Möllerström, Erik
    et al.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Energiteknik. Uppsala University, Uppsala, Sweden.
    Ottermo, Fredric
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Energiteknik.
    Goude, Anders
    Uppsala University, Uppsala, Sweden.
    Eriksson, Sandra
    Uppsala University, Uppsala, Sweden.
    Hylander, Jonny
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Energiteknik.
    Bernhoff, Hans
    Uppsala University, Uppsala, Sweden.
    Turbulence influence on wind energy extraction for a medium size vertical axis wind turbine2016Inngår i: Wind Energy, ISSN 1095-4244, E-ISSN 1099-1824, Vol. 19, nr 11, s. 1963-1973Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The relation between power performance and turbulence intensity for a VAWT H-rotor is studied using logged data from a 14 month (discontinuous) period with the H-rotor operating in wind speeds up to 9 m/s. The turbine, designed originally for a nominal power of 200 kW, operated during this period mostly in a restricted mode due to mechanical concerns, reaching power levels up to about 80 kW. Two different approaches are used for presenting results, one that can be compared to power curves consistent with the International Electrotechnical Commission (IEC) standard and one that allows isolating the effect of turbulence from the cubic variation of power with wind speed. Accounting for this effect, the turbine still shows slightly higher efficiency at higher turbulence, proposing that the H-rotor is well suited for wind sites with turbulent winds. The operational data are also used to create a Cp(λ) curve, showing slightly lower Cp compared with a curve simulated by a double multiple streamtube model. Copyright © 2016 John Wiley & Sons, Ltd.

  • 100.
    Möllerström, Erik
    et al.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Energiteknik. Division for Electricity, Department of Engineering Sciences, Uppsala University, PO Box 534, SE - 751 21 Uppsala, SwedenDivision for Electricity, Department of Engineering Sciences, Uppsala University, Uppsala, Sweden.
    Ottermo, Fredric
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Energiteknik.
    Hylander, Jonny
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Energiteknik.
    Bernhoff, Hans
    Division for Electricity, Department of Engineering Sciences, Uppsala University, PO Box 534, SE - 751 21 Uppsala, SwedenDivision for Electricity, Department of Engineering Sciences, Uppsala University, Uppsala, Sweden.
    Avoidance of resonances in a semi-guy-wired vertical axis wind turbine2014Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Resonance analysis for a vertical axis wind turbine is performed. The turbine may be described as semi-guy wired, being bolted stiffly to the ground as well as supported by guy wires. The influence of the first mode eigen frequency of the guy wires and how it is affected by wind load is examined. Using beam theory, an analytical model for calculating the first mode eigen frequency of the guy wire for different wind loads is derived. The analytical model is verified with FEM-simulations and then used to assemble a diagram showing how to combine the wire size, inclination angle and pre-tension for an eigen frequency range over the 3P load for nominal rotational speed and for a certain effective spring force acting on the tower. This diagram, here called an EA-T diagram, may be used as a quick tool for comparing wire setups and a similar diagram can be used for other guy wired structures.

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