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  • 101.
    Edberg, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Reläskyddssystem för småskalig vattenkraft: En fallstudie för rekommenderad uppgradering av reläskyddssystem2016Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    This thesis aims to propose a recommended upgrade for the generator protectionsystems in small hydropower stations. The hydropower stations examined areBrantafors, Djupafors, Horkoneryd, Kallinge ,Karlsnäs, Ronneby and Verperyd. Therecommended generator protection systems are developed from regulations basedon constitutions from Svenska Kraftnät and Elsäkerhetsverket. The recommendationpresented in this thesis is a lowest recommendation for the generator protectionsystems of small hydropower stations and in some cases the owner of the powerplant may request above this lowest level of protection.

    The overall documentation of the stations has been inadequate and many parametersare unknown in the stations and therefore assumptions have been made. Theassumptions have a big influence on the short circuit calculations which affects therecommended settings for short circuit protection and therefore a conservativeapproach has been used.

    The result of this thesis is that the hydro power station Ronneby can’t manage therequirements specified from Svenska Kraftnät, and therefore the protection system inthe hydro power station need to be adjusted. The hydropower stations Brantaforsand Verperyd can with minor adjustments meet the recommended generatorprotection. On the stations Djupafors, Horkoneryd, Kallinge and Karlsnäs largerupgrades of the generator protection systems need to be done to fulfill therecommended protection system.

  • 102.
    Edoff, Marika
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Lindahl, Johan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Wätjen, Timo
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Nyberg, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Gas flow sputtering of Cu(In,Ga)Se-2 for thin film solar cells2015Inngår i: 2015 IEEE 42ND PHOTOVOLTAIC SPECIALIST CONFERENCE (PVSC), 2015Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Gas flow sputtering of Cu(In,Ga)Se-2 (CIGS) from two opposing Cu(In,Ga)Se-2 targets with slightly Cu-poor stoichiometry was performed, using i) selenium only provided by the target and ii) using additional selenium from an elemental source inside the sputtering system. In both cases the composition of the sputtered CIGS film was similar to the target. A sputter process without additional selenium supply led to poor cell results at about 2 % efficiency. After introducing a posttreatment in selenium atmosphere immediately after the sputter deposition, the cell results were dramatically improved to 12 %. With selenium added during the sputtering process, 13.7 % conversion efficiency was obtained without any post treatment. Gas flow sputtering uses a high gas flow to transport the material from the plasma to the growing film, thereby the atoms will be thermalized, similarly to in an evaporation process. Reactant gases can be supplied close to the substrate, outside the plasma, thereby reducing the risk for sputter damage.

  • 103. Egusquiza, A.
    et al.
    Izkara, J.L.
    Gandini, A.
    Energy efficiency improvement in historic urban environments: From decision support systems to co-creation strategies2018Inngår i: Conference Report: The 3rd International Conference on Energy Efficiency in Historic Buildings / [ed] Tor Broström, Lisa Nilsen and Susanna Carlsten, Uppsala University, 2018, s. 576-584Konferansepaper (Fagfellevurdert)
  • 104.
    Ekergård, Boel
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Eriksson, Sandra
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Boström, Cecilia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Leijon, Mats
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Supplementing rare-earth metal with ferrite in wave power generatorInngår i: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682Artikkel i tidsskrift (Fagfellevurdert)
  • 105.
    Ekergård, Boel
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Leijon, Mats
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Analysis of longitudinal ends effects in a Linear Permanent Magnet GeneratorArtikkel i tidsskrift (Fagfellevurdert)
  • 106.
    Ekergård, Boel
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Leijon, Mats
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Ideal Analytical Expression of the Magnetic Circuit in a Permanent Magnet Linear Machine2013Inngår i: Proceedings of the Ecological Vehicles and Renewable Energies (EVER), 2013, 2013, s. 1-6Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The aim of this paper is to presents a study and derived expressions of the magnetic flux density in the air-gap of the linear synchronous permanent magnet generator, utilized in the wave energy converter. The significance of a well-modelled magnetic flux density-term is important, when, for example, modelling the induced voltage and dimension the support structure due to the magnetic force between the stator and translator at no load situation.

  • 107.
    Ekergård, Boel
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Leijon, Mats
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Tolerance Analysis in a Linear Permanent Magnet GeneratorArtikkel i tidsskrift (Fagfellevurdert)
  • 108. El Gohary, Fouad
    Microgrid Economics: Incentivizing Self-Consumption of Solar Electricity in a DC Microgrid2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
  • 109.
    El Zein, Musadag
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper.
    Off-grid Wind Power Systems: Planning and Decision Making2019Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    There are definitely many reasons for choosing off-grid wind power systems. Few key ones involve the positive enhancement of societies, economies and natural environments. From a project developers’ perspective these systems provide a large potential market, which can cover a wide range of applications with relatively reasonable costs.  In spite of this, many challenges may interfere with the diffusion and the success of such systems.

    In the report we discuss the various factors affecting  the implementation of off-grid wind power systems and demonstrate some of the challenges project developers may be facing during the planning stage. Some of these include the acceptance of stakeholders (local inhabitants in particular) and the securing of the financing of the projects.  Another noted challenge lying outside the control of project developers was found to be the absence of encouraging policies and incentives.

    As a conclusion the thesis provides a set of self-interpreted recommendations along with a flow chart. The concluded summary indicates some key factors that project developers should be aware of and careful when dealing with, these which include: The choice of the site, verification of projects’ economics along with the securing of a convenient finance. The recommendations also point out the great advantage in having local developers as these tend to be more capable in building relations with the local citizens and politicians.

  • 110. Eleftheriadou, Eleni
    et al.
    Haralambopoulos, Dias
    Polatidis, Heracles
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper.
    A Multi-Criteria Approach to Sitting Wind Farms in Lesvos Greece2004Konferansepaper (Fagfellevurdert)
  • 111. Ellegård, Kajsa
    et al.
    Vrotsou, Katerina
    Widén, Joakim
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    VISUAL-TimePAcTS/energy use - a software application for visualizing energy use from activities performed2010Inngår i: Proceedings of the 3rd International Conference on Energy Systems with IT, Älvsjö, Sweden, March 16-17, 2010, 2010Konferansepaper (Fagfellevurdert)
  • 112. Ellegård, Kajsa
    et al.
    Widén, Joakim
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Elanvändning i vardagen: En kunskapsöversikt inom ELAN-programmet2006Rapport (Fagfellevurdert)
  • 113.
    Ellegård, Kajsa
    et al.
    Linköping University.
    Widén, Joakim
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Vrotsou, Katerina
    Appliances facilitating everyday life - electricity use derived from daily activities2011Inngår i: Proceedings of the World Renewable Energy Congress, Linköping, Sweden, May 8-13, 2011, 2011Konferansepaper (Fagfellevurdert)
  • 114.
    Enarsson, Pär
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper.
    Hedenmo, Otto
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper.
    Sillevis Smitt, Dirk-Jan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper.
    Energy Optimisation of a Building: a Case Study of Ekebyvallen, Uppsala: Profitable investments in a world with rising energy prices2013Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    Energy prices are on the rise, and with it the interest in saving energy. In the housing sector this means that methods for energy optimising buildings, retrofitting, are increasingly important. There are many studies concerning the retrofitting of buildings built before 2000, but less concerning buildings of more recent date. In cooperation with the housing company Uppsalahem, this report explores minor retrofitting solutions for the apartment buildings in Ekebyvallen/Uppsala which were built 2007. The aim was foremost to find solutions for Ekebyvallen but also to assess the possibilities of applying them to a wider range of buildings. A simulation of the energy balance in one of the buildings in Ekebyvallen was performed with the software VIP energy. The simulation together with a field study show weak spots of the energy usage in the buildings and based on these four retrofitting solutions were proposed. The methods; 1) reducing the airflow in the ventilation units, 2) adjusting the heating in common areas, 3) reducing air leakage out of buildings and 4) adjusting the settings of lighting sensors and timers. All are effectively free from investments and also applicable on buildings with similar issues. Thus, these are effective methods of saving energy and consequently, saving money in recently built buildings. The methods are tailored for Ekebyvallen but are with benefit considered for apartment buildings of both recent date and those built before 2000.

  • 115.
    Eriksson, Joakim
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Synthesis of thin films of the Olivines Fe2SiS4 and Mn2SiS4 by magnetron sputtering and annealing2017Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    The photovoltaic industry attracts a lot of interest from researchers worldwide due to active integration of the solar cells. The main idea here is to convert solar energy into electricity. One type of solar cell that shows potential in replacing today’s crystalline silicon cells is the thin film solar cell (TFSC). Yet, the sun absorbing semiconductors used in the commercial TFSCs contain scarce elements such as indium, cadmium and tellurium, which may cause problems if the technique is going to grow to a big scale energy producer. Earth abundant sun absorbing materials are therefore of great interest, and several possible replacements are under investigation. 

    In this project two olivine structured ternary metal chalcogenides were investigated: manganese silicon sulfide (Mn2SiS4) and iron silicon sulfide (Fe2SiS4). The goal was to deposit thin films by reactive magnetron sputtering from manganese/iron and silicon targets with mixture of Ar and H2S gas. Afterwards the films were crystallized by a sulfurization process at high temperature. The samples were created with a composition gradient and investigated by SEM, EDS and XRD. Results showed that a single phase of Mn2SiS4 was successfully created in thin film form for the first time.

    Multiple attempts on manufacturing Fe2SiS4 were performed, but didn't show sufficient progress yet. The analysis showed formation of pyrite (FeS2), pyrrhotite (Fe1-xS, x<0.2) and SiS2 phases instead of the targeted material. In both cases it is important to provide additional studies to determine if the selected compounds could be used as an absorber layer in TFSC structures.

  • 116.
    Eriksson, Petra
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Historisk-filosofiska fakulteten, Konstvetenskapliga institutionen, Kulturvård.
    Character defining elements: Relations between heritage regulations, user perspectives and energy saving objectives2018Inngår i: Conference Report: The 3rd International Conference on Energy Efficiency in Historic Buildings / [ed] Tor Broström, Lisa Nilsen and Susanna Carlsten, Uppsala University, 2018, s. 549-556Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The challenge to convert the Swedish building stock to the energy targets as it is set out in national building regulations applies to all buildings. Likewise planning and building legislation states that all buildings should be treated with caution regarding actions that could cause losses of technical, historical, environmental and cultural values. By using the world heritage city of Visby as a case study this paper aims to deepen the understanding of how these values are embedded in the physical expressions through identifying the character defining elements, of buildings. This is performed by examining what is stated by experts in official documents and by non-experts through questionnaires and workshops with house owners and inhabitants. By a transparent designation of character defining elements the advantages of energy improvements can be more clearly balanced with possible losses of value. The outcome of this study will contribute to a method where the better understanding of how heritage values are defined by characteristic elements, from both a top down and a bottom up perspective can help to improve policies and guidelines for adopting energy improvements in existing buildings.

  • 117.
    Eriksson, Rickard
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad mekanik, Byggteknik.
    Fuktstyrning av inomhusklimatet på Skoklosters slott: En utvärdering av avfuktning, skyddsvärme och fuktstyrd ventilation2016Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [en]

    Moisture control of the indoor climate in Skokloster

    castle

    Rickard Eriksson

    Moisture control aims to reduce the risks associated with high relative humidity (RH)

    to avoid the emergence and growth of mold. In historic buildings with little or no

    demand for thermal comfort there are, to lower RH, mainly three active climate

    actions. These are heating, dehumidification and adaptive ventilation. The methods

    have been used in Skokloster castle (an unheated baroque castle between Uppsala

    and Stockholm) for three years to enable decision making of what climate control

    strategy that can prevent mold growth in a energy efficient way. Each action lasted for

    a year in three different case study rooms. To see the effect of the actions, three

    reference rooms with no actions were used. Temperature and RH was measured for

    all years and rooms. In the case study rooms energy use was registered.

    The result shows that the need for active climate control has been low, which can be

    shown by studying the energy use. The energy use is generally low for all actions and

    should not be crucial for the future choices. The result is in many ways difficult to

    interpret, but it shows that it would be too risky not to apply moisture control in

    Skokloster castle. An important conclusion is that it is largely the exceptions that have

    navigated the equipment and that the exceptions therefore should navigate the choice

    of the climate control strategy.

  • 118.
    Eriksson, Sandra
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Kjellin, Jon
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Bernhoff, Hans
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Tip Speed ratio control of a 200 kW VAWT with synchronous generator and variable DC voltage2013Inngår i: Energy Science & Engineering, ISSN 2050-0505, Vol. 1, nr 3, s. 135-143Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A novel control method for a fixed-pitch variable speed wind turbine is introduced and experimental results are presented. The measured absorbed power and rotational speed, together with a look-up table for the aerodynamic efficiency, are used to estimate the wind speed reaching the turbine as well as the tip speed ratio. Thereby, the control is independent on wind speed measurements and the wind turbine itself is used as an anemometer. Tip speed ratio control is implemented by comparing the estimated tip speed ratio to a reference value and adjusting the DC voltage level accordingly. Tip speed ratio control benefits from that the aerodynamic efficiency hardly varies with changing tip speed ratio when close to its optimum value. Experimental results from a 200 kW vertical axis wind turbine are presented. The voltage from the permanent magnet generator is passively rectified and the alternating DC voltage is then inverted, filtered, transformed, and grid connected. The estimated wind speed is compared with the measured wind speed. The absorbed power when tip speed ratio control has been implemented is shown. It is concluded that the presented control method works and some future improvements are discussed.

  • 119.
    Eriksson, William
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper.
    Tillståndsövervakning av fjärrstyrda distribuerade frånskiljare i mellanspänningsnätet2019Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    This thesis studied the possibilities to monitor disconnectors’ operating times to indicate when maintenance needs to be performed. The main hypothesis of this study was that the operational time in a disconnector manoeuvre, open or close, correlates with the resistance in the mechanical components. If the operational time deviates too much from the baseline duration, then this may indicate that the disconnector needs to be maintained. Five substudies were conducted to study if it was possible to monitor the operating time and if the logged operating times had been affected by external conditions. Together they illustrated it might be possible to monitor operating times, but this study cannot state it with certainty based on the available data. From the results, it was possible to see that normal operating times for disconnectors varied within a group of disconnectors of the same type and manufacturer. Why it differed within groups of the same type and manufacturer might be explained by the effects of external conditions. It was shown that a varying transfer time occurred when logging the operation times in the front end processor. Furthermore, the year of production of the disconnector affected the median operating time, but it did not affect the operating time in an intuitive way, that is the operating time did not get longer for older disconnectors. Also, the geographical position of the disconnector may affect the operating time. When these external conditions were considered, disconnectors were concluded necessary to be studied individually. If disconnectors would be studied individually condition monitoring might be possible, although, it is not possible at the moment because of the lack of observations per disconnector.

  • 120. Exner, D.
    et al.
    Larcher, M.
    Belleri, A.
    Troi, A.
    Haas, F.
    The “Waaghaus” of Bolzano: Energy efficiency, hygrothermal risk and ventilation strategy evaluation for a heritage building2018Inngår i: Conference Report: The 3rd International Conference on Energy Efficiency in Historic Buildings / [ed] Tor Broström, Lisa Nilsen and Susanna Carlsten, Uppsala University, 2018, s. 135-144Konferansepaper (Fagfellevurdert)
  • 121.
    Fachrizal, Reza
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad mekanik, Byggteknik.
    Munkhammar, Joakim
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad mekanik, Byggteknik.
    Increasing the photovoltaic self-consumption and reducing peak loads in residential buildings with electric vehicle smart charging2019Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    This paper presents an electric vehicle (EV) smart charging scheme at residential buildings based on installed photovoltaic (PV) output and household electricity consumption. The proposed EV charging scheme is designed to determine the optimal EV charging schedules for the purpose of minimizing the load variance or flattening the load profile. When the net-load is taken into account in the smart charging scheme, not only the peak load can be reduced, but also the PV self-consumption in the building can be increased. The charging scheduling problem is formulated and solved with a quadratic programming approach. The departure and arrival time and the distance covered by vehicle in each trip are specifically modelled based on available statistic data from Swedish travel survey. The scheme is applied on simulated typical Swedish detached houses without electric heating. The aggregation of distributed smart charging in multiple housesis conducted and compared to the smart charging in a single house. Numerical results are presented to show the effectiveness of the proposed smart charging scheme. Positive results on both the PV self-consumption and the peak load reduction are achieved.

  • 122.
    Fantazzini, Dean
    et al.
    Moscow School of Economics.
    Höök, Mikael
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Globala energisystem.
    Angelantoni, André
    Post Peak Living.
    Global oil risks in the early 21st Century2011Inngår i: Energy Policy, ISSN 0301-4215, E-ISSN 1873-6777, Vol. 39, nr 12, s. 7865-7873Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Deepwater Horizon incident demonstrated that most of the oil left is deep offshore or in other difficult to reach locations. Moreover, obtaining the oil remaining in currently producing reservoirs requires additional equipment and technology that comes at a higher price in both capital and energy. In this regard, the physical limitations on producing ever-increasing quantities of oil are highlighted as well as the possibility of the peak of production occurring this decade. The economics of oil supply and demand are also briefly discussed showing why the available supply is basically fixed in the short to medium term. Also, an alarm bell for economic recessions is shown to be when energy takes a disproportionate amount of total consumer expenditures. In this context, risk mitigation practices in government and business are called for. As for the former, early education of the citizenry of the risk of economic contraction is a prudent policy to minimize potential future social discord. As for the latter, all business operations should be examined with the aim of building in resilience and preparing for a scenario in which capital and energy are much more expensive than in the business-as-usual one.

  • 123. Femenías, P.
    et al.
    Eriksson, Petra
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Historisk-filosofiska fakulteten, Konstvetenskapliga institutionen, Kulturvård.
    Thuvander, L.
    Mörk, K.
    Wahlgren, P.
    Johansson, P.
    Value creation by re-renovation: Focus on the user perspective2018Inngår i: Conference Report: The 3rd International Conference on Energy Efficiency in Historic Buildings / [ed] Tor Broström, Lisa Nilsen and Susanna Carlsten, Uppsala University, 2018, s. 172-181Konferansepaper (Fagfellevurdert)
  • 124.
    Flyckt, Alexander
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Lokalt likströmsnät för kontorsbyggnader försedda med solceller: En ekonomisk och teknisk utvärdering2018Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    This thesis evaluates a local direct current grid (DC-grid) wherefour office buildings with photo-voltaic (PV) facilities has beenconnected. The power system has been analyzed and a model of the gridhas been developed to quantify the increased own consumption and thereduction of power peaks. The results has been used to evaluate thegrid from an economic point of view to answer if the installation ofthe grid was profitable. The grid has also been evaluated from atechnical standpoint and future possibilities has been identified.The study shows that an own consumption of solar power was increasedfrom 81,6 per cent in average to 99,2 per cent, which resulted in areduction of annual consumed power by 34 MWh. The power peaks wasreduced with 196 kW in total annually. The analysis also shows thatthe electrical contract can be changed for in one of the buildings.The annual operating costs was reduced by 13 kSEK along with thereduction in energy equating to roughly 34 kSEK in savings, resultingin approximately 47 kSEK of total annually savings. With aninvestment cost of 531 kSEK and a cost of capital set to 5 per cent,the installed DC-grid is profitable. Future possibilities identifiedwas to connect more buildings and PV systems to the grid, analyzeelectrical consumption for greater understanding, implementation ofenergy storage and fast electrical vehicle chargers.

  • 125.
    Flygare, Carl
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för samhällsbyggnad och industriell teknik.
    A market-based instrument for renewable energy: Modelling a dynamic price function for local areas2019Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    This thesis describes the current situation of the electrical grid on a general level and contemporary support policies for residents who feed renewably produced electricity into the grid within a Swedish context. It shows which issues currently exists and suggests a new way to value overproduced renewable electricity which is not self-consumed. This way is called a dynamic price function (DPF), and this thesis models, simulates and analyzes the DPF in order to create an economic incentive to support the balance of the electrical grid – one of its most important parameters. The suggested DPF could potentially work with any renewable source in any area, but the focus in this thesis has been on solar power-systems for households in local areas. While the currently support policies, which uses static models to value overproduced renewable electricity, have created important incentives for the initial penetration of solar power among local residents they do not scale well as the share of renewable production on a local level increase. This might cause negative impacts on the electrical grid. The thesis’ results show that by designing the DPF in certain ways it is possible to create an economic incentive for different behaviors. The most promising design incorporates three different incentives at the same time and they are: 1) to incentivize the initial penetration of solar power in local areas which do not have any production, 2) to incentivize a higher share of solar power, but not too high, and 3) to procure storage possibilities for overproduced electricity. These incentives do not only encourage a more even geographical distribution of solar power, but also allow for a higher share of solar power in the energy system without risking the balance of the grid.

  • 126.
    Fors, Erik
    SLU, Institutionen för energi och teknik.
    Kaffesump som substrat i biogasanläggningar eller som bränsle i fjärrvärmeverk: en studie av effekter på växthusgasutsläpp och kostnader2013Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    Each year, the coffee machines at Ericsson in Kista produce around 100 tons of ground coffee waste.

    The companies Coor Service Management, Löfbergs Lila and Selecta are all responsible for different

    stages in the logistical chain in delivering coffee and, together with Ericsson, they want to increase

    their environmental benefit. The plan is to produce biogas through anaerobic digestion instead of

    incinerating the coffee waste in a heating plant. The results are to be presented as different business

    cases in which different biogas plants are compared with the reference case (heating plant),

    comparing costs and environmental impacts.

    There are two major environmental benefits from producing biogas; reduced carbon dioxide

    emissions from when fossile fule is replaced by carbon neutral biogas, and reduced emissions from

    returning digestate from the bio reactor to farmland instead of using industrial fertelizer.

    In order to determine the biogas potential in coffee waste, a couple of properties had to be

    determined in a laboratory. Properties such as the dry substance content, heating value, moisture

    content and ash content. The results show that 100 tons coffee waste could produce around 16 500

    Nm3 biogas which would contain 163 MWh.

    The biogas reactor and upgrade plant both need energy gas to function and uses around 14 MWh of

    the produced gas. In the end, the resulting upgraded biogas contains 149 MWh energy. Such an

    amount of gas can replace 15,1 m3 of diesel and thus reduce carbon dioxide emissions by 39,4 ton.

    The emissions from running the reactor and upgrade plant, combined with methane leakage

    amounts to 4,8 ton carbon dioxide.

    All of the biogas plants that were examined returns digestate and nutrients to farmlands which

    reduces the need for industrial fertelizer. The production of fertelizer uses alot of energy, and by

    returning digestate a reduction of 58 GJ energy and 3 ton CO2 can be achieved. This is not the case

    with the heat plant which instead has to place some of its produced ashes in landfills.

    If the exergy content in the biogas is compared to that of the heat it shows that there is a point to

    making gas instead of incinerating the waste. The biogas has about 50 % higher exergy content than

    the heat has and therefore it is possible to utilize the substrate more efficiently.

    Transporting coffee waste from Ericsson to different biogas plants will result in increased carbon

    dioxide emissions. The three plants investigated in this thesis are Henriksdals sewage treatment

    plant, the Himmerfjärd plant and Uppsala biogas plant. For each plant, drivning distance, pre

    treatment requirements of the coffee waste, and related costs were determined. Using methods

    from the Network for transportation and enviroment, the emissions for each case were calculated.

    The results show that the Henriksdal case will increase carbon dioxide emissions by two tons per

    year, and the other cases will increase emissions by four tons.

    The result from combining laboratory work, simulations and calculations show that the case where

    Henriksdal recives the coffee waste will reduce carbon dioxide emissions by 15,1 ton at a cost of

    72 000 kr per year. The case with the Himmerfjärd plant will reduce emissions by 13,8 ton at a cost of

    74 000 kr per year. The final case with Uppsala biogas plant will reduce emissions by 13,7 ton at the

    cost of 107 000 kr per year. And thus there are environmental benefits from producing biogas from

    the coffee waste, but they do come at a cost.

  • 127.
    Forsström, William
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Utredning av frekvensregleringens påverkan på mekanisk utrustning i en kaplanturbin2015Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    As a consequence of increasing wind power installations in the Nordic grid the last years, the need for regulating power has become larger. In the Nordic grid, regulating power is mainly provided by hydro power. One part of the regulating power is called frequency control, which ensures that the grid frequency is stable and close to 50 Hz.

    However, setting the turbine into frequency controlled operation may cause stress and wear of the components in the mechanical control system. Frequency controlling implies large and frequent servo forces and longer travelling distance of the sliding bearings in the Kaplan turbine.

    Based on one selected Kaplan turbine, Selsfors G1, measurements and MATLAB calculations have been performed in order to determine forces and movements of the linkage system. With these forces and movements as input, stresses and fatigue have been determined as well as sliding distances, bearing pressures and wear of bearings during a typical lifetime of 40 years.

    The results indicate that no severe wear exists on the bearings during 40 years of service. This is valid for Selsfors G1, where self-lubricating greaseless Orkot bearings are installed. The wear is much smaller than the largest allowed bearing clearance, as long as the bearings are mounted correctly and free from dirt and oil. For turbines with grease or oil lubricated bearings, the result might differ.

    The highest average stresses have been recorded in the links in the runner. A very simple Finite Element Analysis has been made for the links, to estimate risk of fatigue. The stresses are much lower compared to the fatigue limit, and thus the risk of fatigue is considered very small.

    In situations where wear and large load changes after all are problems, a change in the turbine regulator settings is recommended. A dead band reduces the sliding distances of the bearings and the amount of load changes remarkably, but causes on the other hand lower turbine efficiency and worse quality of the frequency control.

  • 128. Fouseki, K.
    et al.
    Bobrova, Y.
    Understanding the change of heritage values over time and its impact onenergy efficiency: Decision-making at residential historic buildings through system dynamics2018Inngår i: Conference Report: The 3rd International Conference on Energy Efficiency in Historic Buildings / [ed] Tor Broström, Lisa Nilsen and Susanna Carlsten, Uppsala University, 2018, s. 11-21Konferansepaper (Fagfellevurdert)
  • 129. Franco, G.
    Nearly Zero Energy Heritage: Taboo or challenge?2018Inngår i: Conference Report: The 3rd International Conference on Energy Efficiency in Historic Buildings / [ed] Tor Broström, Lisa Nilsen and Susanna Carlsten, Uppsala University, 2018, s. 567-575Konferansepaper (Fagfellevurdert)
  • 130.
    Fredriksson, Jonatan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Anpassning av småskaliga vattenkraftverk för ö-drift av lokalt elnät2019Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    This master thesis examines technical requirements for small hydro power plants (HPP) to operate proximate parts of the power grid in island mode. The work examines how small hydropower can be modified and complemented with additional technologies to achieve sufficient frequency control capabilities. A case study was performed within the concession area of power grid operator Ålem Energy. One of the HPPs, located in Skälleryd, is owned by Ålem Energy and became the focal point of the study. Relevant parts of the concession area were surveyed for properties such as system inertia, electric load and available power. Furthermore, a model of Kaplan turbine 1 in Skälleryd HPP was created with the purpose of studying the benefits of bypassing regulation control from the wicket gates directly to the runner. The method was tested in an off-grid islanding test. Frequency control of the turbine was tested powering electric heaters and, using a new method, controlling a virtual power grid. Finally, a theory was developed to estimate the transient disturbance resilience (TDR) of a power grid. The theory was applied to the HPP in Skälleryd to suggest modifications for the plant to achieve sufficient islanding capabilities.

    The survey of the power system revealed a promising potential for the HPPs to operate in island mode, especially at later stages when the grid spans several HPPs for more system inertia. The available power from the HPPs was however strongly seasonal which imposes flexibility on a future plan of action for engaging the grid in island mode. The method of controlling the turbine power from the runner proved to have several difficulties. Firstly, the current hydraulics system was not able to freely control the runner as the hydrodynamic forces on the runner blades were too large. Secondly, the method was found to be unstable due to inherent amplification of speed deviations. Furthermore, the low inertia at Skälleryd is likely detrimental to the lone frequency control of the turbine. Therefore other methods for improving frequency control were suggested.

    The developed theory for TDR was used to create charts describing the TDR for various combinations of system inertia and regulation speed. By studying the proprieties of Skälleryd HPP in the charts the necessary modifications could be rationally chosen. A frequency regulating dummy load was found to be the simplest option. A control scheme was suggested with the dummy load performing primary frequency control and the turbines at Skälleryd performing secondary control, restoring the dummy load to its nominal state.

  • 131. Fuglseth, M.
    et al.
    Berg, F.
    Sandberg-Kristoffersen, B.
    Boro, M.
    Life cycle assessment of Villa Dammen: User-driven energy efficiency versus new construction2018Inngår i: Conference Report: The 3rd International Conference on Energy Efficiency in Historic Buildings / [ed] Tor Broström, Lisa Nilsen and Susanna Carlsten, Uppsala University, 2018, s. 246-254Konferansepaper (Fagfellevurdert)
  • 132.
    Gallagher, Johnny
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper.
    An Assessment of the Discrepancy Between Operational Assessment and Wind Resource Assessment for a Wind Farm in Ireland2014Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    An accurate wind resource assessment (WRA) is crucial in energy prediction as the power is directly proportional to the wind speed cubed. This thesis analyses the discrepancy between operational assessment and WRA for a wind farm located on a moderately complex terrain in Ireland. As part of this research, a WRA was undertaken and the results were input to two wind farm design tools, WindPro and WindSim, to estimate the annual energy production.

    Two and a half years of data was available from a 50m met mast. The data was analysed and filtered to ascertain and limit the usage of erroneous data. The dataset was then correlated with an available online dataset utilising the Measure Correlate Predict (MCP) module in WindPro in order to estimate the long term wind resource at the site.

    The wind resource was then used to determine the annual energy produced at the site using both WindPro and WindSim. A loss of 8% was applied to the energy calculations for comparison with the original WRA.

    The results demonstrate the energy production from the original energy prediction, undertaken by a leading wind consultancy prior to construction, was overestimated by an average 10.19% over the three years of operation. The averaged wind speed at hub height in the original WRA was 8.2m/s. However, the prediction undertaken using WindPro in this study estimated an average hub height wind speed of 8.0m/s while WindSim estimated an average of 7.36m/s. These differing results had a significant contribution to the difference in Annual Energy Production (AEP).

    The calculated annual energy results were an overestimation of energy production by an average of 8.10% utilising WindPro, while WindSim underestimated the energy output by just 0.11%.

  • 133.
    Garcia Teran, Jessica
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper.
    Positional Analysis of Wave Power: Applied at the Pacific Ocean in Mexico.2013Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    The energy transition has started. The key is to find an alternative to uneconomical and unsustainable energy production. In this sense it is a challenge to develop renewable energy technologies suitable for the present and proper for the future. Uppsala University is driving the Lysekil project at its Division of Electricity. The aim is to design an environmentally friendly energy system with wave energy converters (WECs) that are simple and strong in design. However, little has been done to know more about its economically feasibility and the social impact of its benefits. Therefore, this research focuses on a positional analysis of a 3 MW Wave Power Park to understand the relevant aspects of implementing this kind of technology. The target area will be at Rosarito, Baja California at the Pacific Ocean in the Northeast of Mexico, a region experiencing increasing energy demand. This thesis combines technical, economical and social aspects. The technical part describes how the device works. The analysis is complemented by describing the current energy situation in Mexico and the social benefits of sustainable energy. Finally, the economical analysis is presented, it is focused on the perspective of the Merchant Power Plant. The review shows that wave power could be economically viable due to its high degree of utilisation. Energy diversification and security, economic and sustainable development, and clean energy are some of the advantages of wave power. Therefore, wave power is an interesting alternative for generating electricity in Mexico. However, the energy sector is highly subsidised, making it difficult for new technologies to enter the market without government participation. Another finding is that in the long run if the equipment cost decreases or subsidies are applied, the technology might be successfully implemented. Environmental consequences are described briefly, concluding that little is known and more research is needed.

    The environmental constraints, economic implications and uncertainties of a high energy future are disturbing. In that sense, renewable energy appears to be unequivocally better than rely to a greater extent on fossil fuels, in the sense that they offer a sustainable development and less environmental damage. 

  • 134. Garrett, M J
    et al.
    Granqvist, Claes Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Basic Sciences and Development: Rethinking Donor Policy2018 (oppl. reissued)Bok (Fagfellevurdert)
  • 135. Georgiou, Andreas
    et al.
    Polatidis, Heracles
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper.
    Haralambopoulos, Dias
    Wind energy resource assessment and development: decision analysis for site evaluation and application in Cyprus’2012Inngår i: Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, ISSN 1556-7036, E-ISSN 1556-7230Artikkel i tidsskrift (Fagfellevurdert)
  • 136.
    Gerdin, Lisa
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Rosengren Keijser, Mira
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Numerical study on jet flow characteristics of high head and large discharge spillways2014Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    Today scale models are used to design spillway structures for hydropower stations. These are expensive and time-consuming to build and alter. This study investigates the possibilities of using numerical simulations in order to facilitate the spillway design process. It would be possible to save time and resources by altering the spillway parameters in the numerical model and thus find an optimal design, which can be further investigated with a scale model.

    However, it is complicated to simulate turbulent flows. Therefore the simulated flows in this study are compared to experimental measurements in order to investigate the accuracy of the numerical model. Ansys software Fluent uses Computational Fluid Dynamics (CFD) to calculate turbulent flows and is used as the simulation tool in this study.

    The simulations were performed on the spillway system of Shuibuya hydropower station. There are five spillway channels with flip bucket terminals and high head. In order to investigate the risk of erosion during large flows the jet throw distance was examined in experiments on a scale model. The same parameter was investigated in this simulation study.

    The acceptable error margin was set 30 % for the comparison between simulated and experimental measurements. All performed simulations met this criterion. It was therefore concluded that Fluent could be used as a sufficiently good approximation tool when it comes to turbulent flows in spillways. 

  • 137.
    Giassi, Marianna
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Castellucci, Valeria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Engström, Jens
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Göteman, Malin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    An economical cost function for the optimization of wave energy converter arrays2019Inngår i: The 29th International Ocean and Polar Engineering Conference, 2019Konferansepaper (Fagfellevurdert)
  • 138.
    Giassi, Marianna
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Thomas, Simon
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Shahroozi, Zahra
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Engström, Jens
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Isberg, Jan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Tosdevin, Tom
    Hann, Martyn
    Göteman, Malin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Preliminary results from a scaled test of arrays of point-absorbers with 6 DOF2019Inngår i: Proceedings of the 13th European Wave and Tidal Energy Conference, 2019Konferansepaper (Fagfellevurdert)
  • 139. Gigliarelli, E.
    et al.
    Calcerano, F.
    Cessari, L.
    Analytic hierarchy process: A multi-criteria decision support approach for the improvement of the energy efficiency of built heritage2018Inngår i: Conference Report: The 3rd International Conference on Energy Efficiency in Historic Buildings / [ed] Tor Broström, Lisa Nilsen and Susanna Carlsten, Uppsala University, 2018, s. 216-225Konferansepaper (Fagfellevurdert)
  • 140.
    Giovannini, Gabriele
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper.
    Wind Farm decommissioning: A perspective on regulations and cost assessment in Italy and Sweden2014Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    Due to a lack of knowledge and experience the best approach to deal with wind farm decommissioning has yet to be determined. To fill this void, this paper analyzed the current status in terms of regulations and cost, regarding the decommissioning in Italy and Sweden.

     

    In order to make a comparison between these two countries, the available research papers and reports on the decommissioning cost assessment, removal methods and regulations were thoroughly investigated. Moreover, detailed estimated dismantling cost data was obtained from a wind farm in Italy.

     

    The Italian cost data were compared with data collected in Sweden and along with them, the regulations and legislations related to how these costs have to be assessed as well as what developers are required to do regarding the decommissioning in the permit issuance were included.

     

    The results of this research show that in decommissioning cost assessment both countries does not allow developers to include the possible revenues due to the scraps and to the recycling of components, although totally different methods are pursued.

     

    Some kind of security to ensure that decommissioning occurs is required, normally a bond. The bond amount is a debt investment in which an investor loans money to an entity (corporate or governmental) that borrows the funds for a defined period of time at a fixed interest rate. In Italy the bond requirements are generally high and it has to be paid completely for the permit issuance. In order to develop significant projects, this kind of approach leads to discourage small investors.

     

    On the contrary, in Sweden the current amount of 300.000 SEK per turbine according to the court precedent, the most widespread during the approval of the permit, is definitely low and represent a level playing field for every investor. Swedish regulations are also more flexible and only in the 28% of the cases studied between the years 2009 and 2012, the entire amount of the bond had to be assured before the installation. However, the malleability with regard to wind farms that do not need to provide any security, together with the low bond amount might endanger the decommissioning accomplishment. 

  • 141.
    Giraldo, Sergio
    et al.
    Catalonia Institute for Energy Research (IREC).
    Neuschitzer, Markus
    Catalonia Institute for Energy Research (IREC).
    Thersleff, Thomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Lopez-Marino, Simon
    Catalonia Institute for Energy Research (IREC).
    Sanchez, Yudania
    Catalonia Institute for Energy Research (IREC).
    Xie, Haibing
    Catalonia Institute for Energy Research (IREC).
    Colina, Monica
    Catalonia Institute for Energy Research (IREC).
    Placidi, Marcel
    Catalonia Institute for Energy Research (IREC).
    Pistor, Paul
    Catalonia Institute for Energy Research (IREC).
    Izquierdo-Roca, Victor
    Catalonia Institute for Energy Research (IREC).
    Leifer, Klaus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Perez-Rodriguez, Alejandro
    Universitat de Barcelona.
    Saucedo, Edgardo
    Catalonia Institute for Energy Research (IREC).
    Large Efficiency Improvement in Cu2ZnSnSe4 Solar Cells by Introducing a Superficial Ge Nanolayer2015Inngår i: Advanced Energy Materials, ISSN 1614-6840, Vol. 5, nr 21, artikkel-id 1501070Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A large improvement of Cu2ZnSnSe4 solar cell efficiency is presented based on the introduction of a Ge superficial nanolayer. This improvement is explained by three complementary effects: the formation of a liquid Ge-related phase, the possible reduction of Sn multicharge states, and the formation of GeOx nanoinclusions, which lead to an impressive solar cell (VOC) increase.

  • 142.
    Giraldo, Sergio
    et al.
    Catalonia Inst Energy Res, Jardins Dones Negre 1, St Adria De Besos 08930, Barcelona, Spain..
    Thersleff, Thomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Larramona, Gerardo
    IMRA Europe SAS, 220 Rue Albert Caquot, F-06904 Sophia Antipolis, France..
    Neuschitzer, Markus
    Catalonia Inst Energy Res, Jardins Dones Negre 1, St Adria De Besos 08930, Barcelona, Spain..
    Pistor, Paul
    Catalonia Inst Energy Res, Jardins Dones Negre 1, St Adria De Besos 08930, Barcelona, Spain..
    Leifer, Klaus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Perez-Rodriguez, Alejandro
    Catalonia Inst Energy Res, Jardins Dones Negre 1, St Adria De Besos 08930, Barcelona, Spain.;Univ Barcelona, IN2UB, C Marti & Franques 1, E-08028 Barcelona, Spain..
    Moisan, Camille
    IMRA Europe SAS, 220 Rue Albert Caquot, F-06904 Sophia Antipolis, France..
    Dennler, Gilles
    IMRA Europe SAS, 220 Rue Albert Caquot, F-06904 Sophia Antipolis, France..
    Saucedo, Edgardo
    Catalonia Inst Energy Res, Jardins Dones Negre 1, St Adria De Besos 08930, Barcelona, Spain..
    Cu2ZnSnSe4 solar cells with 10.6% efficiency through innovative absorber engineering with Ge superficial nanolayer2016Inngår i: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 24, nr 10, s. 1359-1367Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In our recently published work, the positive effect of a Ge nanolayer introduced into the processing of Cu2ZnSnSe4 absorbers (CZTSe) was demonstrated. In this contribution, the complete optimization of this new approach is presented for the first time. Hence, the optimum Ge nanolayer thickness range is defined in order to achieve an improved performance of the devices, obtaining a record efficiency of 10.6%. By employing this optimized approach, the open-circuit voltage (V-OC) is boosted for our pure selenide CZTSe up to 489 mV, leading to V-OC deficit among the lowest reported so far in kesterite technology. Additionally, two important effects related to the Ge are unambiguously demonstrated that might be the origin of the V-OC boost: the improvement of the grain size and the corresponding crystalline quality, and the interaction between Ge and Na that allows for dynamic control over the CZTSe doping. Finally, evidences pointing to the origin of the deterioration of devices properties for large Ge concentrations are presented.

  • 143.
    Gkiala Fikari, Stamatia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Modeling and Simulation of an Autonomous Hybrid Power System2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    In this report, the modeling process and operation of an autonomous hybrid power system is studied. It is built based on a hypothetical case study of electrification of a remote village of 100 inhabitants in Kenya. The power demand is estimated and the costs of equipment components are specified after extensive research, so that the techno-economical design of the system can be carried out. The microgrid consists of photovoltaics, wind turbine, batteries, diesel genset, basic loads and water pumping and purification load. The system is modeled and simulated in terms of power management and its operation as well as the performance of the dispatch strategy is assessed. Problems like the management of extra power or tackling the deficit of power in the system are addressed. The model represents reliably the behavior of the microgrid and several improving actions are suggested.

  • 144.
    GOMEZ SARA, JOSE ORLANDO
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper.
    ASSESSMENT OF THE OFFSHORE WIND POTENTIAL IN THE CARIBBEAN SEA TO SATISFY THE DEMAND OF ELECTRICITY IN LATIN AMERICA AND THE CARIBBEAN REGION2019Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    The offshore wind potential of the Caribbean Sea has barely been exploited. Currently, the offshore wind power industry in Latin America and the Caribbean region is still at very early stages, leaving aside an important resource that otherwise could contribute to satisfy the growing energy demand of the zone. In this study the possibilities arising from a massive exploitation of the wind resource in the Caribbean Sea are assessed. The objective is to investigate if the resources contained in it would be sufficient to satisfy the energy demand of Latin America and the Caribbean, which is foreseen to be about 1900 TWh/year by 2020.

    To address this question, the “Infinite wind farm” concept is used as a simple way to model the meteorological behaviour and the wind speed in the area. The model is utilized in combination with the bathymetric data of the Caribbean Sea and with a simple economic analysis, to evaluate what the requirements to satisfy the energy demand would be in terms of area, number of turbines, and levelized cost of energy (LCoE). The assessment is performed utilizing different turbine sizes, and inter-turbine separations to find the combination that minimizes the LCoE.

    It is found that the energy demand of Latin America and the Caribbean could be satisfied using only 125000 km2 (4.5% of the total Caribbean Sea area) of waters shallower than 25m at a cost of 69 €/MWh, if the turbines were separated 6.5D from one another and if they had a rotor diameter of 250m. In that case, 47760 turbines should be installed using only conventional monopile foundations. 

  • 145.
    Good, Clara
    et al.
    UiT Arctic Univ Norway, Dept Phys & Technol, Tromsø, Norway.
    Shepero, Mahmoud
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Munkhammar, Joakim
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Boström, Tobias
    UiT Arctic Univ Norway, Dept Phys & Technol, Tromsø, Norway.
    Scenario-based modelling of the potential for solar energy charging of electric vehicles in two Scandinavian cities2019Inngår i: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 168, s. 111-125Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In order to contribute to the reduction of greenhouse gas emissions, electric vehicles (EVs) should be charged using electricity from renewable energy sources. This paper describes a study of photovoltaics (PV) utilization for EV charging in two Scandinavian cities: Tromsø in Norway and Uppsala in Sweden, with the objective to evaluate self-sufficiency and self-consumption.

    The suitable areas for PV were determined using building area statistics and utilization factors. The PV yield was simulated for integration scenarios of 10%-100% of the suitable area. EV charging patterns were generated using a stochastic model based on travel survey data. The scenarios include EV penetration of 10%-100% of the personal vehicle fleet.

    The results show that the PV energy yield could cover the EV load in most of the scenarios, but that the temporal load match could be improved. The energy balance was positive for all seasons and EV levels if the PV integration was over 50%. The highest self-sufficiency was achieved in Tromsø during summer, due to the longer days. For high EV penetration and low PV integration, the self-sufficiency was higher in Uppsala, indicating that installed PV power is more important than yield profile above a certain number of EVs.

    Fulltekst tilgjengelig fra 2020-11-19 10:22
  • 146.
    Goude, Anders
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Rossander, Morgan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Force measurements on a VAWT blade in parked conditions2017Inngår i: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 10, nr 12, artikkel-id 1954Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The forces on a turbine at extreme wind conditions when the turbine is parked is one of the most important design cases for the survivability of a turbine. In this work, the forces on a blade and its support arms have been measured on a 12 kW straight-bladed vertical axis wind turbine at an open site. Two cases are tested: one during electrical braking of the turbine, which allows it to rotate slowly, and one with the turbine mechanically fixed with the leading edge of the blade facing the main wind direction. The force variations with respect to wind direction are investigated, and it is seen that significant variations in forces depend on the wind direction. The measurements show that for the fixed case, when subjected to the same wind speed, the forces are lower when the blade faces the wind direction. The results also show that due to the lower forces at this particular wind direction, the average forces for the fixed blade are notably lower. Hence, it is possible to reduce the forces on a turbine blade, simply by taking the dominating wind direction into account when the turbine is parked. The measurements also show that a positive torque is generated from the blade for most wind directions, which causes the turbine to rotate in the electrically-braked case. These rotations will cause increased fatigue loads on the turbine blade.

  • 147.
    Grabbe, Mårten
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Hydro-Kinetic Energy Conversion: Resource and Technology2013Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The kinetic energy present in tidal currents and other water courses has long been appreciated as a vast resource of renewable energy. The work presented in this doctoral thesis is devoted to both the characteristics of the hydro-kinetic resource and the technology for energy conversion.

    An assessment of the tidal energy resource in Norwegian waters has been carried out based on available data in pilot books. More than 100 sites have been identified as interesting with a total estimated theoretical resource—i.e. the kinetic energy in the undisturbed flow—in the range of 17 TWh. A second study was performed to analyse the velocity distributions presented by tidal currents, regulated rivers and unregulated rivers. The focus is on the possible degree of utilization (or capacity factor), the fraction of converted energy and the ratio of maximum to rated velocity, all of which are believed to be important characteristics of the resource affecting the economic viability of a hydro-kinetic energy converter.

    The concept for hydro-kinetic energy conversion studied in this thesis comprises a vertical axis turbine coupled to a directly driven permanent magnet generator. One such cable wound laboratory generator has been constructed and an experimental setup for deployment in the river Dalälven has been finalized as part of this thesis work. It has been shown, through simulations and experiments, that the generator design at hand can meet the system requirements in the expected range of operation. Experience from winding the prototype generators suggests that improvements of the stator slot geometry can be implemented and, according to simulations, decrease the stator weight by 11% and decrease the load angle by 17%. The decrease in load angle opens the possibility to reduce the amount of permanent magnetic material in the design.

    Delarbeid
    1. A review of the tidal current energy resource in Norway
    Åpne denne publikasjonen i ny fane eller vindu >>A review of the tidal current energy resource in Norway
    2009 (engelsk)Inngår i: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 13, nr 8, s. 1898-1909Artikkel, forskningsoversikt (Fagfellevurdert) Published
    Abstract [en]

    As interest in renewable energy sources is steadily on the rise, tidal current energy is receiving more and more attention from politicans, industrialists, and academics. In this article, the conditions for and potential of tidal currents as an energy resource in Norway are reviewed. There having been a relatively small amount of academic work published in this particular field, closely related topics such as the energy situation in Norway in general, the oceanography of the Norwegian coastline, and numerical models of tidal currents in Norwegian waters are also examined. Two published tidal energy resource assessments are reviewed and compared to a desktop study made specifically for this review based on available data in pilot books. The argument is made that tidal current energy ought to be an important option for Norway in terms of renewable energy.

    sted, utgiver, år, opplag, sider
    Elsevier, 2009
    Emneord
    Tidal current, Renewable energy, Ocean energy
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-113144 (URN)10.1016/j.rser.2009.01.026 (DOI)000269135000012 ()1364-0321 (ISBN)
    Tilgjengelig fra: 2010-10-28 Laget: 2010-01-25 Sist oppdatert: 2018-01-12bibliografisk kontrollert
    2. On the velocity distribution for hydro-kinetic energy conversion from tidal currents and rivers
    Åpne denne publikasjonen i ny fane eller vindu >>On the velocity distribution for hydro-kinetic energy conversion from tidal currents and rivers
    2013 (engelsk)Inngår i: Journal of Renewable and Sustainable Energy, ISSN 1941-7012, E-ISSN 1941-7012, Vol. 5, nr 2, s. 023115-Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Tidal currents and rivers are promising sources of renewable energy given that suitable turbines for kinetic energy conversion are developed. To be economically and technically feasible, a velocity distribution that can give a high degree of utilization (or capacity factor), while the ratio of maximum to rated velocity is low would be preferable. The rated velocity is defined as the velocity at which rated power is achieved. Despite many attempts to estimate the resource, however, reports on the possible degree of utilisation from tidal currents and rivers are scarce.

    In this paper the velocity distribution from a number of regulated rivers, unregulated rivers and tidal currents have been analysed regarding the degree of utilisation, the fraction of converted energy and the ratio of maximum to rated velocity. Two methods have been used for choosing the rated velocity; one aiming at a high fraction of converted energy and one aiming at a high degree of utilisation.

    Using the first method, with a rated velocity close to the maximum velocity, it is unlikely that the turbine will reach the cut-out velocity. This results in, on average, a degree of utilisation of 23% for regulated rivers, 19% for unregulated rivers and 17% for tidal currents while converting roughly 30-40% of the kinetic energy. Choosing a rated velocity closer to the mean velocity resulted in, on average, a degree of utilisation of 57% for regulated rivers, 52% for unregulated rivers and 45% for tidal currents. The ratio of maximum to rated velocity would still be no higher than 2.0 for regulated rivers, 1.2 for unregulated rivers and 1.6 for tidal currents. This implies that the velocity distribution of both rivers and tidal currents is promising for kinetic energy conversion. These results, however, do not include weather related effects or extreme velocities such as the 50-year velocity. A velocity factor is introduced to describe what degree of utilisation can be expected at a site. The velocity factor is defined as the ratio U-max/U-rate at the desired degree of utilisation, and serves as an early indicator of the suitability of a site. 

    sted, utgiver, år, opplag, sider
    American Institute of Physics (AIP), 2013
    Emneord
    tidal currents, rivers, degree of utilisation, marine current energy, capacity factor, renewable energy, velocity factor
    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot elektricitetslära
    Identifikatorer
    urn:nbn:se:uu:diva-195499 (URN)10.1063/1.4795398 (DOI)000318242100037 ()
    Tilgjengelig fra: 2013-04-12 Laget: 2013-02-25 Sist oppdatert: 2017-12-06bibliografisk kontrollert
    3. A low-speed generator for energy conversion from marine currents: experimental validation of simulation
    Åpne denne publikasjonen i ny fane eller vindu >>A low-speed generator for energy conversion from marine currents: experimental validation of simulation
    2008 (engelsk)Inngår i: Proceedings of the Institution of mechanical engineers. Part A, journal of power and energy, ISSN 0957-6509, E-ISSN 2041-2967, Vol. 222, nr 4, s. 381-388Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    A low-speed permanent magnet (PM) cable wound generator for electrical energy conversion from marine or tidal currents has been designed and constructed. A key feature of this variable speed direct drive generator is its capability to efficiently generate electricity from tidal currents with very low velocities, in the order of 1 m/s. In arriving at an appropriate design for the generator typical characteristics of tidal currents were considered. Using these characteristics as input, and accounting for the electromagnetic losses, detailed computer simulations using a finite-element method software were carried out to come up with the final design. Various parameters that can influence the generator design are presented. An experimental set-up has been constructed based on the above-mentioned design in order to study the electrical and mechanical performance of the generator through a variety of experiments. The power input for this set-up is a variable speed motor, capable of operating the generator at rotational speeds of 0–16 r/min, representing tidal currents with very low velocities. The generator presented in this paper may be beneficial for a better understanding of an appropriate design and layout of tidal energy conversion systems.

    Emneord
    finite-element method, marine currents, permanent magnet generator, tidal power
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-96614 (URN)10.1243/09576509JPE567 (DOI)000258167400005 ()
    Tilgjengelig fra: 2008-01-11 Laget: 2008-01-11 Sist oppdatert: 2017-12-14bibliografisk kontrollert
    4. Matching a permanent magnet synchronous generator to a fixed pitch vertical axis turbine for marine current energy conversion
    Åpne denne publikasjonen i ny fane eller vindu >>Matching a permanent magnet synchronous generator to a fixed pitch vertical axis turbine for marine current energy conversion
    Vise andre…
    2009 (engelsk)Inngår i: IEEE Journal of Oceanic Engineering, ISSN 0364-9059, E-ISSN 1558-1691, Vol. 34, nr 1, s. 24-31Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Extracting energy from a free-flow marine current using a vertical axis fixed pitch turbine requires a generator that can handle varying speeds and loads, since such a turbine gives maximum power capture for a fixed tip speed ratio. A prototype of such a generator has been designed and constructed. In this paper, its variable speed and load operation is evaluated, both in terms of how the constructed generator performs in relation to simulations, and in terms of how the generator could perform with three different fixed pitch turbines. Measurements of root mean square (RMS) voltage and current differ 10% from simulations. Performance analysis with example turbines shows that the generator can match fixed tip speed ratio operation of several turbines for current speeds between 0.5 and 2.5 m/s.

    Emneord
    Fixed tip speed ratio operation, permanent magnet generators, tidal power generation, variable speed generator, vertical axis turbine
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-96617 (URN)10.1109/JOE.2008.2010658 (DOI)000264618000003 ()
    Tilgjengelig fra: 2008-01-11 Laget: 2008-01-11 Sist oppdatert: 2017-12-14bibliografisk kontrollert
    5. A Permanent Magnet Generator for Energy Conversion from Marine Currents: No Load and Load Experiments
    Åpne denne publikasjonen i ny fane eller vindu >>A Permanent Magnet Generator for Energy Conversion from Marine Currents: No Load and Load Experiments
    2012 (engelsk)Inngår i: ISNR Renewable Energy, ISSN 2090-7451, Vol. 2012, s. 489379-Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    This paper presents experiments and measurements on a low speed permanent magnet cable wound generator for marine currentenergy conversion.Measurements were made for no load and nominal load (4.44Ω/phase) conditions at nominal speed (10 rpm).For either load condition, the magnetic fields in the air gap were also measured. The measurements on the generator werecompared with the corresponding finite element method simulations used to design the machine. It is shown in the paper thatmeasurements and corresponding case simulations show good agreement. At nominal speed, the measured and simulated loadvoltages (nominal load) differ less than 1% for the rms values and less than 5% for peak values. At no load, measured and simulatedvoltages had larger differences, that is, <9% for rms values and <5% for peak values. Harmonic analyses of measured and simulatedphase voltages and currents show only the presence of third harmonics. The percentage of harmonics in the measured data wascomparable with the corresponding predictions of the simulations. The discussions and results presented in the paper could bebeneficial for future design of efficient and reliable marine current energy converter systems.

    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot elektricitetslära
    Identifikatorer
    urn:nbn:se:uu:diva-176990 (URN)10.5402/2012/489379 (DOI)
    Tilgjengelig fra: 2012-06-29 Laget: 2012-06-29 Sist oppdatert: 2013-03-22bibliografisk kontrollert
    6. On the Stator Slot Geometry of a Cable Wound Generator for Hydrokinetic Energy Conversion
    Åpne denne publikasjonen i ny fane eller vindu >>On the Stator Slot Geometry of a Cable Wound Generator for Hydrokinetic Energy Conversion
    2015 (engelsk)Inngår i: Scientific World Journal, ISSN 1537-744X, E-ISSN 1537-744X, artikkel-id 812149Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    In this paper, the stator slot geometry of a cable wound permanent magnet synchronous generator for hydro-kinetic energy conversion is evaluated. When designing generators, practical experience is of great importance to result in a realizable design. Therefore, practical experience from winding two cable wound generators is used to propose optimized dimensions of different parts in the stator slot geometry. A thorough investigation is performed through simulations of how small geometrical changes alter the generator performance. Simulations are performed by using the finite element method (FEM) to solve coupled field and circuit equations. The parameter study shows that small changes in the geometry can have large affect on the performance and the generator dimensions. Furthermore, it is concluded that the load angle is especially sensitive to small geometrical changes. A new generator design is proposed which shows improved efficiency, reduced weight and a possibility to decrease the expensive permanent magnet material by almost one fifth.

    Emneord
    permanent magnet, synchronous generator, tidal energy, hydro-kinetic energy conversion, cable wound
    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot elektricitetslära
    Identifikatorer
    urn:nbn:se:uu:diva-195501 (URN)10.1155/2015/812149 (DOI)
    Tilgjengelig fra: 2013-02-25 Laget: 2013-02-25 Sist oppdatert: 2017-12-06bibliografisk kontrollert
    7. Design of an experimental setup for hydro-kinetic energy conversion
    Åpne denne publikasjonen i ny fane eller vindu >>Design of an experimental setup for hydro-kinetic energy conversion
    Vise andre…
    2009 (engelsk)Inngår i: International Journal on Hydropower & Dams, ISSN 1352-2523, Vol. 16, nr 5, s. 112-116Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    A hydro-kinetic energy project has been underway in Sweden since 2000, and an in-stream prototype setup for experiments at a site in a Swedish river is now in progress. The system comprises a vertical axis turbine and a directly driven permanent magnet generator. Methods and choices used in designing the system are described here. The turbine and generator are evaluated based on measurements and CFD simulations of conditions at the site for the experimental setup.

    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-113145 (URN)1352-2523 (ISBN)
    Tilgjengelig fra: 2010-01-25 Laget: 2010-01-25 Sist oppdatert: 2016-04-14bibliografisk kontrollert
    8. Efficiency of a Directly Driven Generator for Hydrokinetic Energy Conversion
    Åpne denne publikasjonen i ny fane eller vindu >>Efficiency of a Directly Driven Generator for Hydrokinetic Energy Conversion
    2013 (engelsk)Inngår i: Advances in Mechanical Engineering, ISSN 1687-8132, E-ISSN 1687-8140, s. 978140-Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    An experimental setup for hydrokinetic energy conversion comprising a vertical axis turbine, a directly driven permanent magnet generator, and a control system has been designed and constructed for deployment in the river Dalälven in Sweden. This paper is devoted to discussing the mechanical and electrical design of the generator used in the experimental setup. The generator housing is designed to be water tight, and it also acts as a support structure for the turbine shaft. The generator efficiency has been measured in the range of 5–16.7 rpm, showing that operation in the low velocity range up to 1.5 m/s is possible with a directly driven generator.

    Emneord
    permanent magnet, cable wound, tidal energy, ocean energy, generator
    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot elektricitetslära
    Identifikatorer
    urn:nbn:se:uu:diva-195876 (URN)10.1155/2013/978140 (DOI)000325895100001 ()
    Tilgjengelig fra: 2013-02-28 Laget: 2013-02-28 Sist oppdatert: 2017-12-06bibliografisk kontrollert
  • 148.
    Grahl, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Energikartläggning av en livsmedelsindustri: samt förslag på energieffektiviserande åtgärder2015Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    This thesis concerns an energy audit of a food industry. The company's business consists of boiling and peeling shrimps, and producing mayonnaise-based salads. This type of work involves energy-intensive processes, such as steam generation, compression of air and refrigeration of large spaces. These needs are supplied with electricity. Furthermore, the industry is a major consumer of district heating, particularly for heating the supply air in the ventilation system. The energy-related processes in the operations consume about 2,300 MWh of electricity and 660 MWh of district heating. There are opportunities to improve the efficiency by controlling the processes, merging different parts of the systems , implementing equipment for energy recovery, and installing more energy-efficient equipment. The primary aim of the food industry is to produce high quality food. In this context it is no wonder that matters that do not affect the primary tasks receive a lower priority. There may, however, be good reason to place these energy-related issues higher on the agenda. 

  • 149.
    Grahn, Elin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Industriell teknik.
    Utveckling och tillämpning av modeller förkvantifiering av de ekonomiska konsekvensernaav ökad förbrukningsflexibilitet inom eldistribution2015Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    One step towards a more sustainable energy system is to create a more flexible electrical grid, where increased demand response among electricity consumers can play an important role. A distribution grid owner can encourage their customers to use electricity more evenly distributed during the day by introducing different types of grid fees such as time-differentiated power tariffs. In this master thesis, the theoretical economic impact of a flattened load profile for a distribution grid owner is investigated. Different factors that impact the distribution grid owner’s economy are identified and two are chosen to be quantified; losses in the grid and the fee to the feeding grid. The possibility to save money by avoiding future investments is discussed but not quantified. Models are developed for modifying an existing load profile, calculating the losses associated with a certain grid and load profile, and calculating the value of a lowered subscribed power to the feeding grid. The models are applied on the distribution grid owner Sala-Heby Energi Elnät AB. The results show that with a load profile that is flattened out 100% every day, which is the theoretical best possible scenario, the losses can be reduced with 2.6% which corresponds to a value of 81 000 SEK. By lowering the subscribed power to the feeding grid as much as the highest peak of the year is reduced in the modified load curve, the cost to the feeding grid would be reduced 1.2 million SEK, or 10% of the fee to the feeding grid. In the 20% curve modification case, which would be more realistic to achieve in reality, the losses decreased by 0.9% which corresponds to a value of 29 000 SEK. Furthermore, the fee to feeding grid would be reduced with 0.34 million SEK which corresponds to 2.8% of the total fee. In summary, the theoretical economic saving potential is around 10 times higher for the fee to feeding grid than for grid losses.

  • 150.
    Grandell, Leena
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Globala energisystem.
    Hall, Charles
    State University of New York.
    Höök, Mikael
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Globala energisystem.
    Energy Return on Investment for Norwegian Oil and Gas from 1991 to 20082011Inngår i: Sustainability, ISSN 2071-1050, E-ISSN 2071-1050, Vol. 3, nr 11, s. 2050-2070Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Norwegian oil and gas fields are relatively new and of high quality, which has led, during recent decades, to very high profitability both financially and in terms of energy production. One useful measure for profitability is Energy Return on Investment, EROI. Our analysis shows that EROI for Norwegian petroleum production ranged from 44:1 in the early 1990s to a maximum of 59:1 in 1996, to about 40:1 in the latter half of the last decade. To compare globally, only very few, if any, resources show such favorable EROI values as those found in the Norwegian oil and gas sector. However, the declining trend in recent years is most likely due to ageing of the fields whereas varying drilling intensity might have a smaller impact on the net energy gain of the fields. We expect the EROI of Norwegian oil and gas production to deteriorate further as the fields become older. More energy-intensive production techniques will gain in importance.

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