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  • 4901.
    Zou, X.
    et al.
    National Engineering Laboratory for Pipeline Safety/Beijing Key Laboratory of Urban Oil and Gas Distribution Technology, China University of Petroleum-Beijing, Fuxue Road No.18, Changping District, Beijing, 102249, China.
    Qiu, R.
    National Engineering Laboratory for Pipeline Safety/Beijing Key Laboratory of Urban Oil and Gas Distribution Technology, China University of Petroleum-Beijing, Fuxue Road No.18, Changping District, Beijing, 102249, China.
    Zhang, B.
    National Engineering Laboratory for Pipeline Safety/Beijing Key Laboratory of Urban Oil and Gas Distribution Technology, China University of Petroleum-Beijing, Fuxue Road No.18, Changping District, Beijing, 102249, China.
    Klemeš, J. J.
    Sustainable Process Integration Laboratory – SPIL, NETME Centre, Faculty of Mechanical Engineering, Brno University of Technology – VUT Brno, Technická 2896/2, Brno, 616 69, Czech Republic.
    Wang, B.
    National & Local Joint Engineering Research Center of Harbor Oil & Gas Storage, Transportation Technology/Zhejiang Provincial Key Laboratory of Petrochemical Pollution Control, Zhejiang Ocean University, No. 1 Haida South Road, Zhoushan, 316022, China.
    Liao, Q.
    National Engineering Laboratory for Pipeline Safety/Beijing Key Laboratory of Urban Oil and Gas Distribution Technology, China University of Petroleum-Beijing, Fuxue Road No.18, Changping District, Beijing, 102249, China.
    Liang, Y.
    National Engineering Laboratory for Pipeline Safety/Beijing Key Laboratory of Urban Oil and Gas Distribution Technology, China University of Petroleum-Beijing, Fuxue Road No.18, Changping District, Beijing, 102249, China.
    Zhang, Haoran
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. Center for Spatial Information Science, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa-shi, Chiba, 277-8568, Japan.
    Roadmap to urban energy internet: Techno-enviro-economic analysis of renewable electricity and natural gas integrated energy system2022In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 373, article id 133888Article in journal (Refereed)
    Abstract [en]

    The integrated energy system which coordinates natural gas, renewable energy, and other energy subsystems is an effective way to promote a low-carbon economy. An effective framework for system assessment and optimisation is a critical issue. This paper takes a natural gas-wind-photovoltaic integrated energy system as the research object and uses the simulation software to analyse its techno-enviro-economic feasibility. Firstly, a mathematical model is customised to optimise the system installation and operation plans. Renewable electricity replaces some natural gas, resulting in pipeline pressure fluctuation. Here, the Stoner Pipeline Simulator software is used to simulate pipeline network operation to quantify the aforementioned pressure fluctuations. The proportion of renewable energy is gradually reduced until the network pressure fluctuation is less than 20% to ensure the stability of pipeline operation. Then, the optimal operation scheme can be determined. Taking three cities in Shandong, China, as cases, the results show that the proposed system is beneficial for urban energy internet development: (i) the total net present cost is reduced by 19.7%, 19.8%, and 20.8%, (ii) annual CO2 emission is reduced by 23.7%, 18.4%, and 12.2%; (iii) the levelised cost of energy is 0.142 $/kWh, 0.143$/kWh, and 0.153$/kWh. 

  • 4902.
    Zou, Zhengping
    et al.
    Beihang Univ, Natl Key Lab Sci & Technol Aeroengine Aerothermod, Collaborat Innovat Ctr Adv Aeroengine, Sch Energy & Power Engn, Beijing 100191, Peoples R China..
    Shao, Fei
    Beihang Univ, Natl Key Lab Sci & Technol Aeroengine Aerothermod, Collaborat Innovat Ctr Adv Aeroengine, Sch Energy & Power Engn, Beijing 100191, Peoples R China..
    Li, Yiran
    Beihang Univ, Natl Key Lab Sci & Technol Aeroengine Aerothermod, Collaborat Innovat Ctr Adv Aeroengine, Sch Energy & Power Engn, Beijing 100191, Peoples R China..
    Zhang, Weihao
    Beihang Univ, Natl Key Lab Sci & Technol Aeroengine Aerothermod, Collaborat Innovat Ctr Adv Aeroengine, Sch Energy & Power Engn, Beijing 100191, Peoples R China..
    Berglund, Albin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences. Beihang Univ, Int Sch, Beijing 100191, Peoples R China.
    Dominant flow structure in the squealer tip gap and its impact on turbine aerodynamic performance2017In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 138, p. 167-184Article in journal (Refereed)
    Abstract [en]

    Tip leakage loss reduction is important for improving the turbine aerodynamic performance. In this paper, the flow field of a transonic high pressure turbine stage with a squealer tip is numerically investigated. The physical mechanism of flow structures inside the cavity that control leakage loss is presented, which is obtained by analyzing the evolution of the flow structures and its influence on the leakage flow rate and momentum at the gap outlet. The impacts of the aerodynamic conditions and geometric parameters, such as blade loading distributions in the tip region, squealer heights, and gap heights, on leakage loss reduction are also discussed. The results show that the scraping vortex generated inside the cavity is the dominant flow structure affecting turbine aerodynamic performance. An aero-labyrinth liked sealing effect is formed by the scraping vortex, which increases the energy dissipation of the leakage flow inside the gap and reduces the equivalent flow area at the gap outlet. The discharge coefficient of the squealer tip is therefore decreased, and the tip leakage loss is reduced accordingly. Variations in the blade loading distribution in the tip region and the squealer geometry change the scraping vortex characteristics, such as the size, intensity, and its position inside the cavity, resulting in a different controlling effect on leakage loss. By reasonable blade tip loading distribution and squealer tip geometry for organizing scraping vortex characteristics, the squealer tip can improve the turbine aerodynamic performance effectively.

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  • 4903.
    Ängalid, Filip
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Utredning av behovsstyrd ventilation: En jämförelse mellan CAV och VAV2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Denna rapport är ett examensarbete på C-nivå som görs i sammarbete med teknikkonsulten Ramböll. Det vanligaste sättet att ventilera en byggnad idag är med så kallad CAV-ventilation (Constant Air Volume). Denna metod bygger på att ett luftflöde bestäms för rummet och upprätthålls med konstant flöde. En annan metod är så kallad VAV (Variable Air Volume) som bygger på att flödet varierar efter behovet. Anledningen till varför man väljer VAV istället för CAV är att med CAV finns det ofta en stor risk att man överventilerar ett rum eller byggnad, just på grund av att flödet är konstant. Problemet med VAV är att det är en högre investeringskostnad än för CAV så metoden lämpar sig bara där energibesparingen är så stor så den täcker mellanskillnaden i pris. Denna utredning visar i vilka typer av rum som det kan löna sig att installera VAV istället för det traditionella CAV-systemet. För att undersöka detta sker simuleringar av fiktiva modeller i programmet IDA Indoor Climate & Energy (IDA). IDA är ett simuleringsverktyg som används till att simulera den termiska komforten i byggnader samt byggnadens energianvändning. De olika rumstyperna som simuleras är: klassrummet, kontoret och mötesrummet. De olika fallen är utformade så att de liknar så som de ser ut i verkligheten både till geometri och nyttjandegrad. Om något av fallen visade sig vara en bra kandidat för att förse med VAV fortsätter utredningen med att fastställa hur stort bör flödet vara för att energibesparingen ska bli så stor så att det täcker investeringskostnaden. Den ekonomiska kalkyleringen sker både med en livscykelkostnadsanalys och med en enklare återbetalningstidskalkyl. Resultatet för simuleringarna visade att den enda rumstypen i denna utredning som var lönsam var mötesrummet. Klassrummet och kontoret visade sig båda ge en förlust. Detta var eftersom nyttjandegraden för dessa rum var så pass hög så att ventilationen med VAV var igång nästan lika mycket som för CAV. För mötesrummet var nyttjandegraden betydligt lägre vilket innebar att energibesparingen blev så pass hög att den täckte den höga investeringskostnaden. För mötesrummet gjordes sedan en flödesanalys som visade att rummets luftflöde bör vara dimensionerat för mellan omkring 20 – 30 personer för att vara en lönsam investering. 

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    Utredning av behovsstyrd ventilation
  • 4904.
    Åberg, Anna
    KTH, School of Architecture and the Built Environment (ABE), Philosophy and History of Technology, History of Science and Technology.
    A Gap in the Grid: Attempts to introduce natural gas in Sweden 1967-19912013Doctoral thesis, monograph (Other academic)
    Abstract [en]

    This thesis follows the process of introducing natural gas in Sweden and the construction of a Northern European gas grid from 1967 to 1991. Natural gas is a relatively unnoticed fuel in Sweden today, but this relative anonymity stands in contrast to an extensive historical activity that has taken place behind the scenes of Swedish energy policy. The single pipeline constructed between Denmark and Sweden in the early 1980s was both preceded and followed by many other attempts to construct a larger natural gas pipeline in the region made in the last 50 years. Åberg traces these attempts while discussing the complex and messy process of constructing and managing a transnational energy infrastructure.Åberg follows actors in Sweden and other countries in their attempts to negotiate and construct a natural gas infrastructure, and puts this process into a national as well as transnational context. The perceived risks and opportunities surrounding natural gas are examined, together with factors that have influenced the development of natural gas in a broader sense. By seeing the changing and messy natural gas projects as arenas where different actors construct and negotiate risks and opportunities, as well as contexualize the projects, Åberg shows how the natural gas sector in Sweden has evolved and taken shape.The study shows that natural gas in Sweden has suffered from unstable actor coalitions on different levels, a difficult market situation, and a changeful political context, especially with regard to energy policy. The import status of the fuel and the consequential transnationality of the natural gas infrastructure have also made the process of constructing a pipeline more complex. However, natural gas was introduced in Sweden, showing that when a strong enough actor coalition agreed that there was enough reason to warrant a natural gas introduction and was ready to join this endeavor, a connection could be achieved. This puts into question to what degree general explanations in terms of finance and policy drive energy decisions, and makes a case for showing how these explanations are adapted into their social and historical contexts in sometimes surprising ways.

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    A Gap in the Grid Anna Åberg
  • 4905.
    Åberg, Magnus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    District Heating Sensitivity to Heat Demand Reductions and Electricity Market Dynamics2012Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Sweden and the rest of the EU member states have to reduce primary energy use andemissions of CO2, and increase the use of renewable energy sources according to the EUclimate change package “20-20-20”. To do this, the energy systems need to use less fossilfuel and to utilise energy resources more efficiently. Reduction of energy use in buildings isan important part of this transformation. In Sweden, district heating is the most commontechnique to supply heat for space heating and domestic hot water to multi-family residentialbuildings in urban areas. Efficiency improvements in buildings connected to district heatingsystems should not be counterproductive from a systems perspective, e.g. causing lessefficient total use of resources and increased global CO2 emissions. A reduced electricityproduction in combined heat and power plants, which may be a result of reduced districtheating demand, is sometimes seen as problematic with regards to emissions of CO2, sincethis electricity is normally considered to replace electricity produced in less efficient fossilfuelledcondensing power plants.This licentiate thesis summarises the first part of a PhD project that studies thepossibilities for Swedish district heating systems to adapt to a reduced demand for heating inbuildings, as well as to changes in energy markets. In this thesis the impact of buildingenergy-efficiency improvements and electricity market dynamics on the operation of districtheating systems and CO2 emissions is investigated.The energy system cost-optimisation software MODEST has been used to study theimpact of heat demand changes on the heat and electricity production in the Swedish districtheating systems in Linköping and Uppsala. MODEST optimisations were also used toinvestigate the impact of electricity price fluctuations on the operation of the Uppsaladistrict heating system, and the interaction between the national power system and allSwedish district heating systems collectively.The results show that energy efficiency improvements in buildings that reduce heatdemand by up to 40 % do not increase global CO2 emissions due to production of districtheating. This is because heat-only production is reduced to a larger extent than combinedheat and power production. The results also show that low electricity prices during winterand a large introduction of intermittent wind and solar power generation in the Swedishpower system can be expected to induce use of electricity for district heat production and tohamper co-generation of electricity in combined heat and power plants.

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  • 4906.
    Åberg, Magnus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    System Effects of Improved Energy Efficiency in Swedish District-Heated Buildings2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    To alleviate global warming, European-Union member states must reduce primary energy use, emit less carbon dioxide (CO2), and increase renewable energy use. Buildings constitute a great potential for energy savings, but saving energy in district-heated buildings influences combined heat and power (CHP) production, other electricity generation, and global CO2 emissions.

     

    This thesis investigates the system effects from Swedish district heating production caused by district heating demand changes due to energy conservation in buildings. The cost-optimising linear programming modelling tools MODEST and FMS, the latter developed in the context of this thesis, are used to describe present district heating production and to investigate the impact of heat-demand reductions in twelve Swedish district heating systems, four of them representing all Swedish district heating.

     

    Energy savings in district-heated, multi-family residential buildings yield a lower, more seasonally levelled district heating demand. These demand changes mainly reduce use of fossil-fuel and biomass for heat production. CHP production is significantly reduced if it supplies intermediate or peak district heating load. The αsystem value (ratio between generated CHP electricity and produced district heating) increases by demand reductions if CHP mainly supplies base district heating load. CO2 emissions due to district heat production depend on the approach used for CO2 assessment of electricity, and are generally reduced with heat demand reductions, unless the share of CHP production is large and the reduced fuel use yields smaller emission reductions than the emission increase from power production that replaces reduced CHP generation.

     

    In total, heat demand reductions reduce CO2 emissions due to Swedish district heating, and the district heating systems even constitute a carbon sink at certain energy conservation levels. If saved biomass replaces fossil fuels elsewhere, a lower heat demand reduces CO2 emissions for every studied district heating system.

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  • 4907.
    Åberg, Magnus
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Carlsson, Jonas
    ekoPerspektiv AB.
    Nilsson, Annica M
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Improved efficiency for distribution and use of district heating: A simulation study of retrofitting a Swedish apartment complex from the 1970's2018In: Journal of Building Engineering, ISSN 2352-7102, Vol. 20, p. 559-568Article in journal (Refereed)
    Abstract [en]

    Important features of the next generation of district heating systems are low distribution heat losses and low distribution temperatures. The purpose of this transition is to compensate for reduced heat demand densities caused by increased energy efficiency in buildings. In Sweden a majority of multi-family residential buildings are connected to district heating networks that are up to 50 years old. This study investigates the possibility to improve building energy efficiency and simultaneously reduce distribution temperatures and losses for a Swedish apartment complex built in the 1970's. The results show that a combination of better insulated building envelopes and ventilation heat recovery can reduce the heat demand in the studied apartment complex by 53%. The improved building energy performance significantly reduces the required supply temperatures for space heating and reduces heat distribution losses to some extent. The heat distribution losses can be reduced further (up to 49%) by replacing central hot water preparation with apartment based heat exchangers. This eliminates heat losses from pipes for domestic hot water supply and hot water circulation. The study concludes that a potential cost-synergy occurs when a holistic strategy is adopted and conventional energy efficiency measures are combined with reduced distribution losses.

  • 4908.
    Åberg, Magnus
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Henning, Dag
    Optimisation of a Swedish district heating system with reduced heat demand due to energy efficiency measures inr esidential buildings2011In: Energy Policy, ISSN 0301-4215, E-ISSN 1873-6777, Vol. 39, no 12, p. 7839-7852Article in journal (Refereed)
    Abstract [en]

    The development towards more energy efficient buildings, as well as the expansion of district heating (DH) networks, is generally considered to reduce environmental impact. But the combined effect of these two progressions is more controversial. A reduced heat demand (HD) due to higher energy efficiency in buildings might hamper co-production of electricity and DH. InSweden,co-produced electricity is normally considered to displace electricity from less efficient European condensing power plants. In this study, a potential HD reduction due to energy efficiency measures in the existing building stock in the Swedish city Linkoping is calculated. The impact of HD reduction on heat and electricity production in the Linkoping DH system is investigated by using the energy system optimisation model MODEST. Energy efficiency measures in buildings reduce seasonal HD variations. Model results show that HD reductions primarily decrease heat-only production.The electricity-to-heat output ratio for the system is increased for HD reductions up to 30%. Local and global CO2 emissions are reduced. If co-produced electricity replaces electricity from coal-fired condensing power plants, a 20% HD reduction is optimal for decreasing global CO2 emissions in the analysed DH system.

  • 4909.
    Åberg, Magnus
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Lingfors, David
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Olauson, Jon
    KTH, Dept Elect & Comp Engn, Stockholm, Sweden.
    Widén, Joakim
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Can electricity market prices control power-to-heat production for peak shaving of renewable power generation?: The case of Sweden2019In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 176, p. 1-14Article in journal (Refereed)
    Abstract [en]

    100% renewable energy systems require high penetration of variable renewable electricity (VRE) generation. This causes the net load in the system to be more variable and could cause operational problems in local power grids. Demand side management (DSM), such as fuel or energy carrier switching in response to a price signal, can provide flexibility to meet the increased variability. This study investigates the impact of VRE production on electricity prices and their potential to act as an incentive to control district heating power-to-heat (P2H) production in order to shave VRE production peaks. Also, the potential to increase P2H production flexibility with additional heat storages is studied. Electricity prices are simulated by modification of historical electricity market supply curves. A heat storage component is implemented in an existing model for district heat production. The results show that P2H production is significantly increased (up to 98%) when electricity prices are influenced by VRE production. Thermal storages further increase the P2H production by up to 46%. The increased P2H production, however, does not necessarily coincide with the peaks of VRE. Thus, in conclusion, the pricing mechanism on the Nord pool electricity market is insufficient to control P2H production for shaving VRE production peaks. (C) 2019 Elsevier Ltd. All rights reserved.

  • 4910.
    Åberg, Magnus
    et al.
    Uppsala University, Sweden.
    Molin, Andreas
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Wäckelgård, Ewa
    Uppsala University, Sweden.
    Moshfegh, Bahram
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Greenhouse Gas Emission from General District Heat use in Sweden: An Approach for Justified Comparisons in Residential Energy Use2009In: Scientific Conference on Energy Saving and Green Energy, Älvsjömässan, Stockholm, 2009Conference paper (Refereed)
    Abstract [en]

    Significant uncertainties regarding the evaluation of environmental impact from the use ofenergy motivates the need for a unified evaluation approach. In this paper a marginalapproach for general evaluation of CO2 equivalent emissions from the use of district heat inSweden is proposed. A predefined national marginal heat production mix is used to define amarginal heat evaluation approach to calculate the greenhouse gas emissions from the use ofdistrict heating. The novel approach offers a method for justified comparisons of differenttypes of energy use. By using the marginal heat evaluation approach it was shown that theevaluation of the electricity used in heat production for district heating is significant for theCO2 equivalent emissions. A survey of general district heating CO2 emission evaluationexamples is also included in the paper. The marginal heat use approach generates high CO2equivalent emission values in comparison with earlier studies. The overall conclusion of thepaper is that there is a need for further research and discussion regarding development ofmethods for energy use evaluation. The general marginal heat use approach is part of thesolution to this problem.

  • 4911.
    Åberg, Magnus
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Nilsson, Annica
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Munkhammar, Joakim
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Luthander, Rasmus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Lingfors, David
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Widén, Joakim
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Electricity self-sufficiency and primary energy use in a Swedish residential community, after building renovation and implementation of photovoltaics, small-scale CHP, and electric vehicles2016In: Proceedings of the 2016 ACEEE Summer Study on Energy Efficiency in Buildings, Pacific Grove, CA, USA, August 21-26, 2016, 2016Conference paper (Refereed)
  • 4912.
    Åberg, Magnus
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Widén, Joakim
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Development, validation and application of a fixed district heating model structure that requires small amounts of input data2013In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 75, p. 74-85Article in journal (Refereed)
    Abstract [en]

    Reducing the energy use of buildings is an important part in reaching the European energy efficiency targets. Consequently, local energy systems need to adapt to a lower demand for heating. A 90% of Swedish multi-family residential buildings use district heating (DH) produced in Sweden’s over 400 DH systems, which use different heat production technologies and fuels. DH system modelling results obtained until now are mostly for particular DH systems and cannot be easily generalised. Here, a fixed model structure (FMS) based on linear programming for cost-optimisaton studies of DH systems is developed requiring only general DH system information. A method for approximating heat demands based on local outdoor temperature data is also developed. A scenario is studied where the FMS is applied to six Swedish DH systems and heat demands are reduced due to energy efficiency improvements in buildings. The results show that the FMS is a useful tool for DH system optimisation studies and that building energy efficiency improvements lead to reduced use of fossil fuels and biomass in DH systems. Also, the share of CHP in the production mix is increased in five of the six DH systems when the heat demand is reduced.

  • 4913.
    Åberg, Magnus
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Widén, Joakim
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Wäckelgård, Ewa
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Henning, Dag
    Large-scale introduction of new residential district-heating loads to increase renewable electricity generation in CHP plants2012In: Proceedings of the World Renewable Energy Forum 2012, Denver, Colorado, USA, May 13-17, 2012, 2012, p. 2407-2414Conference paper (Refereed)
    Abstract [en]

    Combined heat and power (CHP) plants enable an efficient use of low-grade energy carriers, such as domestic waste and biomass, for co-generation of district heating (DH) and electricity. Expected future building energy-efficiency improvements reduce the demand for space heating and may limit the possibilities to cogenerate electricity. The use of DH for new applications, such as household appliances, can improve conditions for co-generation of electricity. This paper investigates the future potential to increase DH demand and co-generation of electricity due to large-scale implementation of household appliances that use DH instead of electricity. The analysis is applied to the DH system in Uppsala, Sweden. Results show that co-generation of electricity and total fuel use increase with implementation of household appliances connected to a building hot water circuit (HWC). The impact on CO2 emissions depends on DH fuel mix and electricity assessment approach.

  • 4914.
    Åbrink, Albin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Civil and Industrial Engineering, Civil Engineering and Built Environment.
    Estimating Photovoltaic capacity using customs data: Model development of the tool NJORD and photovoltaics' characterization and impact on the African continent2023Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Photovoltaics (PV) is one of the fastest growing power sources in the world in the last twenty years, being the most installed power source in almost half of the world's countries in 2020. Despite this, precise tracking of installations of PV does not exist in most of the world's markets due to PVs unique scalability and modularity. One way to try to estimate how much PV is installed in the world is by following trade data between countries, which is the goal of NJORD. In NJORD the installed capacity of PV is estimated in the world by following the trade of PV as closely as possible and calculating an estimation based on module prices, weights and other factors collected from the market. The ITC reports trade in different levels, 6-digits codes called HS-codes are the most precise codes that are shared between all countries reporting to ITC, and NTL-codes that are more precise than the HS-codes but individual per country.

    By identifying existing NTL-codes and incorporating them into the NJORD models, estimations can be made that lie within 10% of the reported publicized data for a set of reference countries with credible PV reporting. Using the same estimation criteria, the model can also estimate installed PV capacity in most of the countries in the world. The NJORD model finds that most countries in the world have PV capacity installed, and that the best reports from the African continent miss some capacity. 

    The estimated PV capacity installed on the African continent correlates with the reported performance towards multiple SDGs, showing that PV has an impact on the continent with the clearest impact on SDG7 “Ensure access to affordable, reliable, sustainable and modern energy for all”, but also an impact on health through a decrease in lung-disease. Off-grid PV plays a large part on the African PV market and it is hard to monitor due to the small size of the systems. NJORD can capture these systems in the estimations in a way that is difficult for the classic collection of data.

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  • 4915. Ågren, G.I.
    et al.
    Wikström, Fredrik
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Modelling carbon allocation - a review1993In: New Zealand Journal of Forestry Science 23(3): 343-353 (1993)Article in journal (Refereed)
  • 4916.
    Ågren, Sebastian
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Energieffektivisering av industribelysning: Planering av belysningsanläggning i mekanisk verkstad2012Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In Uppsala, Sweden, Vattenfall has a combined heat and power plant. On the premises there is an engineering workshop with old fluorescent and mercury lamps that need to be replaced. This provides a great opportunity to save energy and money by installing more efficient lighting. The main purpose of this study was to present two functional and energy efficient lighting systems including control system. The lighting systems were designed by investigating the working environment, measuring illuminance and by simulations in the software DIALux. Additionally Life Cycle Cost (LCC) was used as an instrument of comparison. One alternative was designed using mainly modern T5 fluorescent lighting. For the other alternative powerful LED-lamps were chosen as the primary light source. The simulations showed the two alternatives to be equally good in regard to performance and energy saving potential. With sustained illuminance level the installed power of both systems was around 34 kW ascompared to 54 kW, the estimated value of the existing lighting system. The LCC, however, differed significantly with the fluorescent alternative having a total cost of 1.1 million SEK over a 20 year period while the same number for the LED alternative being 2.2 million SEK. The difference in LCC makes fluorescent lighting the preferable alternative. The present consumption is estimated to 142 MWh. The fluorescent lighting alternative would have an approximated energy consumption of 78.6 MWh including a control system, giving an energy saving potential of 45 %.

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  • 4917.
    Ågren, Simon
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Electricity.
    Dygnsreglering av småskalig vattenkraft i Jädraån2023Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The purpose of this project was to investigate the viability of daily production planning of the small-scale hydropower plants owned by Småkraft AB in Jädraån. In order to achieve this a number of characteristics of the river and the power plants first had to be estimated. This included the size of the reservoirs located by the power plants as well as the efficiency profiles of the power plants.

    The above data was combined with already available information regarding the head, peak power production, maximum discharge and flow times between the power plants. A model of the river and the included power plants was then developed using Matlab and Simulink. In the model the reservoir levels by the power plants are directed towards different levels during different hours of the day, depending on when electricity prices are the highest. Data that can be inserted into the model includes river runoff and electricity prices. The model can then be used to evaluate the best way to operate the power plants under certain conditions.

    For this project, the model was then used to evaluate different modes of operation for three different runoff schemes. The electricity prices that the operation was evaluated for were the average hourly prices during 2022. The model was also used to examine the potential benefits of increasing the maximum discharge at one of the power stations.

    The evaluation found that moving production to hours with higher electricity prices enables an increase in revenue of about 7-14% depending on the present water flows. There are however many uncertainties involved in the modelling and physical tests would be required to validate the results. No clear benefits of increasing the maximum discharge were found.

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  • 4918.
    Åhlund, Anton
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS), Energy Science. Halmstad University.
    Solar Cooling: -A study of two thermal systems2015Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Electricity-driven air-conditioning is energy-intensive and puts a strain to many grids during hot periods in warm climates. Solar thermal cooling could be an alternative to conventional cooling, using a renewable energy source and supplying the most energy during peak demand periods with insignificant effect to the electric grid.

    Office buildings in warm climates have high cooling loads, naturally peaking during daytime because of occupancy and ambient temperature. Thus, office buildings have a seemingly advantageous relationship between the possible supply of solar thermal energy and cooling demand. With this background, solar cooling systems for two office buildings with the same dimensions are investigated, placed in a tropical- and a sub-tropical location.

    There are great differences in the design conditions for solar cooling systems in the tropics and the sub-tropics, between the chosen locations Manila and Abu Dhabi more specifically.

    Manila has a quite evenly distributed cooling load while Abu Dhabi has a strongly pronounced summer season with very high maximum cooling loads, while the winter temperatures are relatively low. The prior described conditions creates a big difference between loads throughout the year, making a thermal chiller less effective in this aspect. However Abu Dhabi is expected to have an overall smoother- and ultimately a more high performance solar cooling system due to lower humidity, which facilitates the important cooling of the chiller.

    Evacuated tube collectors were used at both sites, where the collectors in Manila needs to be larger relative to the chiller cooling capacity, in order to compensate for the irregularity of direct solar radiation.

    The electricity price in Abu Dhabi is too low for the solar cooling system to be economically feasible compared to a conventional system, where the net values over 20 years are 163 000 € and 127 000 €, respectively. Manila has on its hand a very high price for electricity, making the 20-year net values for both the solar cooling- and the conventional system approximately 170 000 €.

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    Solar Cooling -A study of two thermal cooling systems
  • 4919.
    Åkerblom, Hampus
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Industrial Ecology.
    Wiberg, Joakim Thanke
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Industrial Ecology.
    Fosforåtervinning genom alkalisk lakning av förbränt avloppsslam2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Projektet har undersökt möjligheten att med basisk lakning skilja ut fosfor från förbränt avloppsslam. Basisk lakning jämfört med sur lakning ger ett sämre fosforutbyte. Men basisk lakning löser samtidigt ut lägre mängder tungmetaller, vilket gör att metoden med basisk lakning kan vara mer lämpad om slutanvändningen återför den lakade produkten till naturen

    Genom att variera parametrarna tid, temperatur och koncentrationer av reagenser gavs resultat i form av de effektivaste förutsättningarna för ett högt fosforutbyte. Allmänt verkar högre temperaturer ge bättre resultat. Blandningsförhållandet mellan förbränt avloppsslam och basisk lakvätska ger högre procentuellt fosforutbyte vid lägre koncentrationer av avloppsslam. Dock kan högre koncentrationer av avloppsslam ändå vara att föredra om denna process ska genomföras i teknisk skala när stora mängder fosfor ska utskiljas på kort tid.

    Problem uppstod när produkten som skulle fälla ut fosfatkristaller istället bildade en okänd gel. Det gick att undvika gelbildningen genom att använda lägre koncentrationer av den basiska lakvätskan. Resultaten av denna studie antyder att gelen sannolikt är en silikatgel. En möjlighet att undvika gelfenomenet vid starkare koncentrationer av den basiska lakvätskan är sannolikt att använda förbränt avloppsslam med lägre koncentrationer av kisel. 

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  • 4920.
    Åkerblom, Signe
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy Systems Analysis.
    Improving energy performance within the framework of the Energy Efficiency Directive2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    It is necessary for large companies to understand and be able to adapt to the industrial transformation towards an increasing focus on energy efficiency, which takes place today. The Energy Efficiency Directive (EED)issued by the European Union has enlarged the focus on working with energy efficiency within large companies. Further, the Swedish government has introduced the law about energy auditing in large companies, which is based on the EED. These regulations encourage companies to develop a management system that includes requirements on conducting energy audits and propose cost effective measures.

     Energy efficiency is already an important aspect within many companies environmental work, however a more developed and systematic approach to energy efficiency than most companies already have is needed in order to fulfill the legal requirements. The Company investigated in this study is one the world’s leading technology companies with more than 9000 employees in Sweden. Currently, they have energy as a significant aspect in their environmental work according to the international management system standard ISO 14001. Today they are also developing their energy work by conducting energy audits in order to comply with the new legislation. This gives a more detailed view of the energy use and potential improvements that can be done, but in order to ensure continual improvements over a long period of time further measures are needed.  Within this study it was investigated what measures a large company needs to implement in order to increase their energy performance and comply with the legislation. By a literature review focusing on management systems as well as interviews within the Company, a complementary study with two companies covered by the EED and three expert interviews, five key factors were identified. These factors are top management commitment, awareness, goals, measurements and evaluation. A model was then developed aligning these factors. Further, concrete proposals for action to manage these factors were presented. By increasing focus on these key factors and implement proposed measures companies will increase their energy performance and make the organization aware of how actions affect a company’s energy performance. 

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  • 4921.
    Åkerlund, Hanna
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Scenarion och potential för energieffektivisering i Uppsala kommuns bostäder fram till år 2050: Ett arbete inom Färdplan 2050 för ett klimatpositivt Uppsala2014Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The purpose of this report is to examine the energy efficiency potential in Uppsala municipality housings, from today to the year of 2050. The study includes both existing and future housings that will be built during these years. On behalf of Naturvårdsverket, Uppsala municipality cooperates with various organizations to produce an energy roadmap to the year 2050. The aim of the energy roadmap is to present a long-term plan on how the municipality should reach the environmental goals. The results from this report will be the foundation for the energy policy in the future.

    The report includes three future scenarios; the reference-, actor- and potential scenario. The reference scenario describes a probable development in energy use where spontaneous rate of energy efficiency measures is assumed. The actor scenario presents the effects of present and planned energy saving projects registered by local partners and the potential scenario shows the potential of reducing energy use in housings. Simulation and calculations showed a potential decrease of energy use by 64% in single-family houses, by 45% in apartment buildings and by 23% in future housings.

    The conclusions of the report are, among others, that BBR´s demands on energy usage are too low to reach the environmental goals and that the energy declarations were not enough to survey the energy efficiency potential. Simulations show that the potential for energy efficiency in Uppsalamunicipality are large. Though, it requires more work concerning energy saving in both existing and future housing to be able to reach the goals.

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  • 4922.
    Ålander, Atte
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Electricity Supply Solutions for an Educational Center in Tanzania2013Independent thesis Advanced level (degree of Master (One Year)), 12 credits / 18 HE creditsStudent thesis
    Abstract [en]

    The aim of this study was to investigate electricity supply solutions for an educationalcenter that is being built in Chonyonyo Tanzania. Off-grid power generation solutions andfurther optimization possibilities were studied for the case.The study was done for Engineers Without Borders in Sweden. Who are working withMavuno Project on the educational center. The school is set to start operating in year 2015with 40 girl students in the beginning. The educational center will help to improve genderequality by offering high quality education in a safe environment for girls in rural area.It is important for the system to be economically and environmentally sustainable. Thearea has great potential for photovoltaic power generation. Thus PV was considered as theprimary power generation and a diesel generator as a reliable backup. The system sizeoptimization was done with HOMER. For the simulations HOMER required componentdata, weather data and load data. Common components were chose with standardproperties, the loads were based on load estimations from year 2011 and the weather datawas acquired from NASA database. The system size optimization result for this base casewas a system with 26 kW PW; 5.5 kW diesel generator, 15 kW converter and 112 T-105batteries. The initial cost of the system was 55 875 €, the total net present cost 92 121 €and the levelized cost of electricity 0.264 €/kWh.In addition three optimization possibilities were studied. First it was studied how thesystem should be designed and how it would affect the system size to have night loads(security lights) use DC and could the system then be extended in blocks. As a result it wasfound out that the system size could be decreased as the inverter losses would be avoided.Also the system extension in blocks was found to be possible. The second study was aboutinverter stacking where multiple inverters can work as one unit. This type of connectionallows only the required number of inverters to run while shutting down the excess ones.This would allow the converter-unit to run with higher efficiency and lower powerconsumption could be achieved. In future with higher loads the system could be easilyextendable by connecting more inverters either in parallel or series depending on what isneeded. Multiple inverters would also offer higher reliability than using one centralizedinverter. The third study examined how the choice of location for a centralized powergeneration affects the cable sizing for the system. As a result it was found that centralizedpower generation should be located close to high loads in order to avoid long runs of thickcables. Future loads should also be considered when choosing the location. For theeducational center the potential locations for centralized power generation were found outto be close to the school buildings and close to the dormitories.

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  • 4923.
    Åman, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    KARTLÄGGNING AV URBAN VINDKRAFT I ELOMRÅDE SE3 OCH SE42021Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Denna kandidatuppsats syftar till att genom en litteraturstudie redogöra för vilka problem och möjligheter som finns för utbyggnad av urban vindkraft i Sverige idag samt kartlägga hur utvecklingen av tätortsnära vindkraft ser ut jämfört med övrig vindkraftsutbyggnad i Sverige. Litteraturstudien visar att vindkraft har störst potential vid en svensk energiomställning men att vinden i urbana miljöer är komplex och metoder för att bedöma vinden behöver utvecklas ytterligare. Vidare kan småskalig vindkraft i urbana miljöer utgöra ett komplement till dagens stora vindkraftparker förutsatt att vindkraftstekniken fortsätter att utvecklas och sjunker i pris. Kartläggningen visar att det finns ett fåtal vindkraftverk uppförda i svenska tätorter och att dessa företrädesvis återfinns i hamnområden. Vidare visar kartläggningen att andelen vindkraftsetableringar som har fått avslag är högre på landsbygden än i tätorter.

  • 4924.
    Åsander, Henrik
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Tillvaratagande av värmeenergi ur gråvatten med värmepump i flerbostadshus2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Large amounts of energy leave homes with wastewater without any effort to return the heated water's thermal energy back to the building. With increased thermal envelope improvements of a traditional nature to meet the nearly zero-energy requirements for residential buildings that will come into effect by the end of 2020, energy losses in buildings can increasingly be allocated to the wastewater leaving the building.

    The aim of this work is to investigate whether significant energy savings in the mentioned area can be obtained, as well as to assess the economic opportunities and prospects for utilizing heat energy from grey water from multi-residential buildings connected to district heating networks with the help of a heat pump. And by that show which factors are shown to influence the operational savings and how sensitive the results are in relation to a selection of these factors. The work consists of and has been carried out in two parts: a literature study and a calculation study.

    Household wastewater can be divided into grey and black water. Grey water is the water that comes from bath, dishes and laundry and black water is the water that is flushed out of the toilets. Separated flows reveal the possibility of utilizing thermal energy directly from grey water, which is also the warmer, volume largest and more manageable fraction, both from a water purification and heat recovery standpoint. Studies on source separated systems show a wide range of benefits, largely by keeping household wastewater separated, such as increased resource efficiency of nitrogen and phosphorus at the wastewater treatment plants. The contamination of heat exchanger surfaces, especially biofilm, poses a challenge when wastewater is used as a heat source and is something that has to be taken into account even when using grey water as a heat source.

    The result of the calculations of an individual case with preheating of domestic hot water, given a series of assumptions, resulted in operational cost savings of approximately SEK 31,000 per year and a present value of these annual savings over 20 years of approximately SEK 355,000. Energy savings amounted to approximately 63,000 kWh per year, which means a reduction of the total need for purchased energy for domestic hot water production by 67 % with an assumption of a final domestic hot water temperature of 55 °C. The sensitivity analysis shows that crucial parameters in the calculation study such as electrical and district heating price, heat pump life and discount rate entail relatively large changes in profit if allowed to vary.

    It is obvious that there are large amounts of energy to potentially recycle. It is also obvious that difficulties cause grey water as a source of heat not be treated easily because, among other things, the long-term development of household water use and high pollution rates are factors that must be considered in addition to the factors brought up in the sensitivity analysis.

    District heating and heat pump combined imply a higher investment than a single heating system, but at the same time is something that can be seen as a tool for utilizing the assumed increasing energy price variations that an increasing proportion of intermittent renewable power generation implies simply by varying heating configuration with changes in energy prices and finding the optimal share. For a property owner, it would at this point be favorable to be able to choose what the cheapest option is currently.

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  • 4925.
    Åström, Christer
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, The Svedberg Laboratory.
    Neutron Irradiation of Concrete at TSL: a Comparison of Nuclide Specific Measurmentswith FLUKA Simulations.2017Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis studies the possibility of using the Monte Carlo simulation program FLUKA to determine the neutron induced radioactivity of concrete walls at the The Svedberg Laboratory (TSL) in Uppsala. If a simulation of the activation would produce reliable results, it would be a useful complement to measurements for the decommissioning and clearance of the buildings of the facility. An experiment was performed in which a concrete core was taken from one of the non-activated walls in the facility. The core was cut into samples and irradiated with a neutron beam. The samples were then measured in a gamma-ray spectroscopy setup, by which the produced radioactive nuclides were identified and their activities determined. The same setup was then simulated in FLUKA. A comparison of the simulations and the measurements shows that the average activity for all nuclides obtained with FLUKA is similar to the measured one, however with large differences for some nuclides. The average ratio of the simulated and measured activities or all nuclides is 1.07 with a standard deviation of 0.55. The obtained results may be useful for future radiological clearance work at TSL.

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    Neutron Irradiation of Concrete at TSL
  • 4926.
    Åström, Frida
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Energieffektiviseringsanalys av ventilationssystemet för ett kraftvärmeverk: En fältstudie utförd i samarbete med Bomhus energi AB och ABB2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Detta arbeta kommer att utreda vilka det vanligaste energiförlusterna för ett kraftvärmeverk är, med fördjupning på förlusterna i deras ventilationssystem.  Kraftvärmeverket som har analyserats i detta arbete är Bomhus energi AB (BEAB) kraftvärmeverk och utredningen har skett i samråd med ABB Energy Efficiency team.    

    Världens energianvändning kan delas in i tre sektorer: industri, transport samt bostad- och servicesektorn. Industrisektorn kan sedan delas in i flera sektorer där massa och pappersindustrin står för majoriteten av energianvändningen i Sverige. Industrisektorn står för ca 64% utav världens el-energiförbrukning. Detta gör att det finns stort intresse i att se över de komponenter som har hög elförbrukning.     

    Fokuset har i detta arbete varit på ventilationssystemet och dess fläktrift. För att få information om vart det kan finnas komponenter som brukar mycket el så har styrsystemets loggar setts över. Besparingspotential har då identifierats i att installera frekvensomriktare till aggregatens fläktar istället för att använda den befintliga spjällregleringen. ABB har tidigare funnit besparingspotential i pumpdrifter för kraftvärmeverk och är därför nu intresserade av att se om det finns någon besparingspotential i ventilationssystemet.

    BEABs ventilation är uppdelad på process och allmänventilation, och genomlysning utav ventilationssystemet är i detta arbete begränsat till allmänventilationen i pannhuset. Detta då processventilationen anses vara korrekt dimensionerat.

    För att få insikt i hur energieffektivisering utav ventilationssystem kan gå tillväga har olika vetenskapliga artiklar rörande ämnet valts ut och analyserats. Som systemet är uppbyggt så sker regleringen utav ventilationen med spjällreglering. Spjällreglering innebär att fläktarna går på konstant flöde och för att uppnå önskad temperatur och tryck i byggnaden så sitter det tryckreglerande spjäll på taket som släpper ut luft ur byggnaden. Denna typ av styrning är inte särskilt energieffektiv, vilket har motiverat detta arbete till att rikta in sig på frekvensomriktare till aggregaten och hur mycket energi som då skulle kunna sparas.  För att få fram besparingspotentialen har hänsyn tagits till aggregatens: nominella volymflöde, fläktverkningsgrad, transmissionsverkningsgrad, flödesreglering, motoreffekt, motorns verkningsgradsklass, matningsspänning, fläkttyp, pumphjulstyp, varaktighetskurva, årgångstid, energipris samt multiplikatorn för Co2-utsläpp. Data har sedan matats in i ABB Energy Save kalkylatorn som då har tagit fram hur mycket energi och pengar som skulle kunna sparas genom att installera en frekvensomriktare.  Om de frekvensomriktare som då har tagits fram för de olika aggregaten skulle installeras så skulle uppskattningsvis ca 67 000 kr/år kunna sparas för kraftvärmeverket. 

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  • 4927. Åström, Stefan
    et al.
    Sandvall, Akram
    IVL Swedish Environmental Research Institute.
    Wisell, Tomas
    IVL Swedish Environmental Research Institute.
    Karlsson, Kenneth
    IVL Swedish Environmental Research Institute.
    Mawdsley, Ingrid
    IVL Swedish Environmental Research Institute.
    Effekter på utsläpp av luftföroreningar från förändrad framtida elbalans i Sverige2022Report (Other academic)
    Abstract [sv]

    I rapporten undersöks hur framtida höga elbehov i flera sektorer (el- och värmeproduktion, bostäder och service, samt industri) kan komma att påverka framtida utsläpp av NOX och små partiklar (PM2,5). Ökad elektrifiering riskerar att fördröja den pågående utsläppsminskningen av NOX till år 2030 men skynda på utsläppsminskningen till år 2050. Effekten på den pågående utsläppsminskningen av PM2,5 riskerar vara fördröjande både år 2030 och 2050.

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  • 4928.
    Çelik, Onur
    et al.
    Adana Alparslan Türkeş Science and Technology University, Adana, Turkey.
    Yilmaz, S. Ece
    Adana Alparslan Türkeş Science and Technology University, Adana, Turkey.
    Yildizhan, Hasan
    Adana Alparslan Türkeş Science and Technology University, Adana, Turkey.
    Ameen, Arman
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Consumer purchasing behavior and its organizational evaluation toward solar water heating system2023In: Energy Reports, E-ISSN 2352-4847, Vol. 10, p. 1589-1601Article in journal (Refereed)
    Abstract [en]

    Renewable energy sources are fundamental to a country’s economic growth. Solar energy is one of these resources that has a favorable effect on economic growth. Turkey’s solar energy industry is still in its early stages. Due to its location and degree of sunshine each year, the country has a great solar potential. Despite the huge potential, solar energy awareness and utilization are not widespread in all parts of Turkey. In order to identify the factors that affect consumers’ decisions to utilize water heating systems, which is a sort of solar energy system, the purpose of this research is to examine these systems. In this study, all factors influencing consumers’ decisions to acquire solar water heating systems were evaluated holistically for the first time. A questionnaire was used in the study, which is a quantitative research technique. The study identifies the variables that influence consumers’ attitudes toward solar collector purchases and assesses the consequences from an organizational point of view. The study’s results act as a guide for decision-makers.

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  • 4929.
    Ögren, Linnéa
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science.
    Wik, Stina
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science.
    Flytande solceller i kombination med vattenkraft i Sverige: En fallstudie över solelpotentialen vid Edensforsens vattenkraftverk och de regelverken som berör hybridtekniken2023Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Forskare är eniga om att jorden utsätts för ständiga klimatförändringar. Detta har lett till att FN tagit fram 17 globala mål som Sverige sedan har formulerat egna miljömål ifrån. En del av den omställning som behöver göras för att nå målen är att byta till en förnybar elproduktion. Det inspirerade till ämnet för examensarbetet, flytande solceller i kombination med vattenkraftverk. Syftet var att ta fram ett underlag för beslutsfattare på energiföretag, vilket innefattar att samla de regelverk som berör hybridtekniken, samt göra en sammanställning av för- och nackdelar med tekniken. Arbetet genomfördes i samarbete med Sydkraft Hydropower AB (SHAB). En av SHABs anläggningar, Edensforsens vattenkraftverk, undersöktes för att beräkna den potentiella solelproduktionen på en del av vattenreservoaren vid vattenkraftverket.

    För att uppnå resultatet gjordes en fallstudie bestående av en litteraturstudie samt simuleringar i Winsun, för att göra en beräkning av solelpotentialen för den specifika vattenytan vid Edensforsen. Resultatet visade att solcellsanläggningen vid Edensforsen skulle kunna nå en årlig elproduktion på 2,15 GWh i oskuggat läge med en utnyttjad yta på 15 000 m2 och 5412 solcellsmoduler. Det finns inte några specifika regelverk för flytande solceller eller hybridtekniken. Författarna har antagit att flytande solceller klassas som vattenverksamhet och därav berörs av de regelverken. Det innebär att en miljöpåverkansbedömning måste göras och en anmälan till mark- och miljödomstolen krävs då den föreslagna verksamheten kommer vara större än 3000 m2.

    Tidigare studier har visat att tekniken är ny och outforskad och att det därför är svårt att säga exakt vilken miljöpåverkan de flytande solcellsanläggningarna skulle ha. Hybridtekniken har fördelar som till exempel en minskad kostnad eftersom det redan finns en nätanslutning vid vattenkraften samt att solcellernas effekt kommer vara högre eftersom de får en kylande effekt från vattnet. De nackdelar som identifierats är bland annat att förankringen av de flytande solcellerna kan bli problematisk eftersom vattennivån kan variera i reservoaren. Även att det kan krävas avancerad teknik för att vattenkraften ska kunna regleras snabbt för att kunna justeras efter solelens produktion.

    Om SHAB skulle välja att implementera flytande solceller vid Edensforsens vatten- kraftverk med den föreslagna ytan skulle den kunna uppnå samma energieffektivitet som den till ytan mest energieffektiva solcellsparken som finns idag i Sverige. Som förslag för fortsatta studier skulle en kostnadsanalys kunna göras för att bredda beslutsunderlaget.

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    Flytande solceller i kombination med vattenkraft i Sverige - En fallstudie över solelpotentialen vid Edensforsens vattenkraftverk och de regelverken som berör hybridtekniken
  • 4930.
    Ögren, Magnus
    Örebro University, School of Science and Technology.
    Stochastic Solutions of Stefan Problems with General Time-Dependent Boundary Conditions2023In: Stochastic Processes, Statistical Methods, and Engineering Mathematics: SPAS 2019, Västerås, Sweden, September 30–October 2 / [ed] Anatoliy Malyarenko; Ying Ni; Milica Rančić; Sergei Silvestrov, Springer, 2023, p. 669-687Chapter in book (Other academic)
    Abstract [en]

    This work deals with the one-dimensional Stefan problem with a general time-dependent boundary condition at the fixed boundary. Stochastic solutions are obtained using discrete random walks, and the results are compared with analytic formulae when they exist, otherwise with numerical solutions from a finite difference method. The innovative part is to model the moving boundary with a random walk method. The results show statistical convergence for many random walkers when Δx→0. Stochastic methods are very competitive in large domains in higher dimensions and has the advantages of generality and ease of implementation. The stochastic method suffers from that longer execution times are required for increased accuracy. Since the code is easily adapted for parallel computing, it is possible to speed up the calculations. Regarding applications for Stefan problems, they have historically been used to model the dynamics of melting ice, and we give such an example here where the fixed boundary condition follows data from observed day temperatures at Örebro airport. Nowadays, there are a large range of examples of applications, such as climate models, the diffusion of lithium-ions in lithium-ion batteries and modelling steam chambers for petroleum extraction.

  • 4931.
    Ögren, Yngve
    et al.
    RISE AB, Box 726 SE-941 28, Piteå, Sweden.
    Sepman, Alexey
    RISE AB, Box 726 SE-941 28, Piteå, Sweden.
    Fooladgar, Ehsan
    RISE AB, Box 726 SE-941 28, Piteå, Sweden.
    Weiland, Fredrik
    RISE AB, Box 726 SE-941 28, Piteå, Sweden.
    Wiinikka, Henrik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science. RISE AB, Box 726 SE-941 28, Piteå, Sweden.
    Development and evaluation of a vision driven sensor for estimating fuel feeding rates in combustion and gasification processes2024In: Energy and AI, ISSN 2666-5468, Vol. 15, article id 100316Article in journal (Refereed)
    Abstract [en]

    A machine vision driven sensor for estimating the instantaneous feeding rate of pelletized fuels was developed and tested experimentally in combustion and gasification processes. The feeding rate was determined from images of the pellets sliding on a transfer chute into the reactor. From the images the apparent area and velocity of the pellets were extracted. Area was determined by a segmentation model created using a machine learning framework and velocities by image registration of two subsequent images. The measured weight of the pelletized fuel passed through the feeding system was in good agreement with the weight estimated by the sensor. The observed variations in the fuel feeding correlated with the variations in the gaseous species concentrations measured in the reactor core and in the exhaust. Since the developed sensor measures the ingoing fuel feeding rate prior to the reactor, its signal could therefore help improve process control.

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  • 4932. Ögren, Yngve
    et al.
    Sepman, Alexey
    Qu, Zhechao
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Schmidt, Florian M.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Wiinikka, Henrik
    Comparison of measurement techniques for temperature and soot concentration in premixed, small-scale burner flames2017In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 31, no 10, p. 11328-11336Article in journal (Refereed)
    Abstract [en]

    Optical and intrusive measurement techniques for temperature and soot concentration in hot reacting flows were tested on a small-scale burner in fuel-rich, oxygen-enriched atmospheric flat flames produced to simulate the environment inside an entrained flow reactor. The optical techniques comprised two-color pyrometry (2C-PYR), laser extinction (LE), and tunable diode laser absorption spectroscopy (TDLAS), and the intrusive methods included fine-wire thermocouple thermometry (TC) and electrical low pressure impactor (ELPI) particle analysis. Vertical profiles of temperature and soot concentration were recorded in flames with different equivalence and O2/N2 ratios. The 2C-PYR and LE data were derived assuming mature soot. Gas temperatures up to 2200 K and soot concentrations up to 3 ppmv were measured. Close to the burner surface, the temperatures obtained with the pyrometer were up to 300 K higher than those measured by TDLAS. Further away from the burner, the difference was within 100 K. The TC-derived temperatures were within 100 K from the TDLAS results for most of the flames. At high signal-to-noise ratio and in flame regions with mature soot, the temperatures measured by 2C-PYR and TDLAS were similar. The soot concentrations determined with 2C-PYR were close to those obtained with LE but lower than the ELPI results. It is concluded that the three optical techniques have good potential for process control applications in combustion and gasification processes. 2C-PYR offers simpler installation and 2D imaging, whereas TDLAS and LE provide better accuracy and dynamic range without calibration procedures.

  • 4933.
    Öhgren, Gustav
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Civil and Industrial Engineering.
    Implementation of a snow loss model to improve the accuracy of hourly simulated PV power generation2024Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In countries with cold winters and substantial snowfall, such as Sweden, snow losses can limit the energy generated from PV systems by up to 100% monthly and up to 20% annually. Therefore, snow loss modeling is required to effectively predict the generated PV electricity in these locations. This thesis investigates the implementation of snow loss models to improve theaccuracy of hourly simulated Photovoltaic (PV) power generation. Four different snow loss models were identified as potential options, which was selected based on the purpose and constraints of the PV power simulation model used. The evaluated models include the Marion Model, The Modified Marion Model, The SunPower Model, and the Combined model, which is a combination of the three other models. The assessment of the snow loss models was conducted using 29 PV reference systems, predominantly located in Sweden (26 systems), with two additional systems in Norway and one in Estonia. The reference systems include known system characteristics, such as PV module parameters, tilt, azimuth, and measured PV power generation data, depending on the systems, between the years 2017-2023.

    Initially, all PV reference systems were simulated without applying the snow loss model, followed by simulations incorporating the snow loss models. The performance of the snow loss models were evaluated by the difference in the coefficient of determination, R2, before and after the respective snow loss model was implemented. Furthermore, all tested models were optimised based on various parameters. For all models except the SunPower model, the optimisation involved adjusting the snow clearing coefficient, and the snow depth threshold, THsnowfall. Following the model optimisation and comparison, all snow loss models demonstrated improved accuracy in compared to the baseline simulations.

    Among these models, the Modified Marion model was recommended due to its low complexity and its notably improved accuracy. Specifically, the Modified Marion model yielded an average monthly improvement in R2 values ranging from 0.1 to 0.14 for all winter months except for March (0.004), with an overall average improvement of 0.0094. The estimated annual snow losses using the Modified Marion model ranged from 0.02% to 12% over the period from 2017 to 2023, with most systems experiencing values between 2% and 6%. Finally, the monthly losses were estimated to reach up to 100% for the northernmost systems. The main challenges of the recommended snow loss model include lower performance in March compared to other winter months for most systems, as well as an overall decreased accuracy for the northernmost systems, where substantial snowfall is present. However, for systems with moderate snowfall, the model generally demonstrated increased performance, which can be of value for Distribution System Owners conducting PV power simulations for grid planning and for solar power forecasting.

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  • 4934.
    Öhlund, Martin
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Ekonomisk Optimering av Systemtemperaturer i Radiatorsystem2020Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The choice of temperatures in heating systems has long been a question for debate in Sweden. For the design engineer, the choice of system temperatures in a heating system has a decisive impact on the cost and in order to stay competitive on the market it is crucial to design the heating system as cost effective as possible. Historically the system temperature in Swedish heating systems has been 80/60 but today we see that the most common temperatures are 55/45. During the 1960´s Östen Sandberg became the leading advocate for a new type of heating system using a low flow principle (LF) for heat distribution. The LF principle requires a larger temperatur difference between the supply and return temperatures for the adequate heating. Advocates of the LF principle claims that large energy savings are possible if an exsisting high flow heating system (HF) undergoes an adjustment to a LF heating system. The question is how accurate is this claim?

    This article shows many advantages with the nowadays common 55/45-HFsystem. A 55/45-HFsystem has relatively low investment costs in comparison with other types of heating systems. Another advantage is the fact that the 55/45-HFsystem is compatible with both district heating and geothermal heat pump heating systems which makes this radiator system suitable as a standardized system. The most economical radiator system is the 80/60-HFsystem, which has a lower investment cost for both radiators and piping in comparison with a 55/45-HFsystem. The claim that LFsystems and the associated LF principle could result in a reduced energy cost for the heating system was not supported. This article shows that the energy savings that comes from the LF principle is negligible in comparison with the heating systems total energy cost. The LF principle could however reduce the risk of an uneven heating distribution in the building due to a more unpredictable regulation of the flow through the radiators. LFsystem disadvantage is an general overall larger investment cost in comparison with a HFsystem.

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    Ekonomisk Optimering av Systemtemperaturer i Radiatorsystem
  • 4935.
    Öhman, Amanda
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering. HYBRIT.
    Karakaya, Emrah
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.).
    Urban, Frauke
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Sustainability, Industrial Dynamics & Entrepreneurship.
    Enabling the transition to a fossil-free steel sector: The conditions for technology transfer for hydrogen-based steelmaking in Europe2022In: Energy Research & Social Science, ISSN 2214-6296, E-ISSN 2214-6326, Vol. 84, p. 102384-, article id 102384Article in journal (Refereed)
    Abstract [en]

    Deep decarbonisation of energy-intensive industries, such as steel production, will be required to achieve the European Union's climate targets. Green hydrogen technology has the potential to reduce the carbon dioxide emissions from iron and steelmaking to nearly zero and mitigate climate change from the industrial sector. The paper is based on an ongoing case in Sweden, where the established firms SSAB, LKAB, and Vattenfall are operating the HYBRIT joint venture. This paper aims to explore the conditions for transferring this technology from Sweden to three primary steel producing countries in Europe: Germany, France and Italy. As a theoretical point of departure, we integrate some concepts from the multi-level perspective and technology transfer theories to better understand transition pathways for hydrogen-based steel production in Europe. We use a case study methodology, including the analysis of more than 20 qualitative interviews and secondary data. The findings of the study conclude that the Swedish iron and steel industry is unique in many ways, yet other European countries are rapidly catching up in hydrogen-based steel production, particularly Germany. Sweden however remains unique in its nearly zero carbon electricity generation and low-cost electricity prices, which can enable green hydrogen production throughout the country. In order to overcome the barriers and create an enabling environment for hydrogen-based steel production, it is key that energy and industry transitions are aligned, that a policy framework that supports these transitions is in place, and that key actors representing all aspects of these transitions cooperate, from industry and research, to academia, policymakers, and civil society.

  • 4936.
    Öhman, Rasmus
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Energikartläggning av lokaler och processer i hyresfastigheten Sörby Urfjäll 37:32013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syftet med denna uppsatts är att utreda energianvändningen i fastigheten Sörby Urfjäll 37:3 och samman ställa en energibalans.

    Mätningar gjordes på elanvändning, av temperaturer i ventilationskanaler och temperatur loggning gjordes i fastigheten. Under platsbesöken undersöktes användningen av maskiner, antalet människor som vistas i de olika delarna av fastigheten samt att maskiner, kylskåp, datorer och lampor räknades och eleffekten på dessa registrerades.

    Utifrån mätningar, statistik och observationer beräknades temperaturverkningsgrader ut på ventilationssystemen, värmetillskott och värmeförluster beräknades. Med utgångspunkt i beräkningar och statistik sammanställdes en energibalans.

    Åtgärder har utifrån de resultat som uppkom under arbetets gång för att effektivisera fastighetens energianvändning tagits fram. Åtgärdernas kostnader och hur invecklade de är varierar från att täta springor och rengöra fönster till att byta ut stora ventilationssystem.

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    Energikartläggning av lokaler och processer
  • 4937.
    Öhrlund, Isak
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Civil and Industrial Engineering, Industrial Engineering and Management.
    Demand Side Response: Exploring How and Why Users Respond to Signals Aimed at Incentivizing a Shift of Electricity Use in Time2020Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    With increased weather-dependent electricity production and electrification at the heart of the ongoing transition away from fossil fuels, peaks in electricity demand are set to increase and become increasingly difficult to meet, which threatens the functioning of the electric power systems that our society depends on. Time-varying electricity rates, which aim to incentivize electricity users to shift their electricity use in time, have been proposed as a key instrument in alleviating grid imbalances and bottlenecks. Previous research has found that users respond to such rates by shifting their electricity use in time, but there is great variability in the observed response between studies that remains unexplained. In other words, it is unclear how and why users respond to time-varying rates, and thus how these so called demand side response policies should be designed to provide the best results.

    This thesis aims to improve our understanding of how and why (not) time-varying rates work by exploring how users respond to both price and non-price signals that aim to incentivize a shift of electricity use in time, and what motivates, discourages, enables and hinders them to respond. This is done through four separate studies that are carried out in contexts where users have been involuntarily subjected to interventions that aim to incentivize demand side response. Using several novel methods, research designs and understudied empirical contexts, the studies also illustrate how biases that are commonly observed in the literature can be avoided and how intervention effects that often remain overlooked can be captured.

    The results suggest that users may hold different motives to respond to signals that aim to incentivize a shift of electricity use in time, including non-financial motives such as a care for the environment and a will to meet the expectations of others. The rhythms and schedules of people’s everyday lives are identified as the most important hindrances for people to engage in demand side response. Notably, there is no evident relationship between how much money users may save by responding to a signal and their actual response. Many users do hold expectations of saving money and claim to engage in demand side response as a result of those expectations, but the fact that users are rarely (if ever) informed of whether their expectations are met or not suggests that many users may actually be willing to engage in demand side response with little or no financial reward. However, there is a risk that users who expect to save money may refrain from or stop engaging in demand side response if their expectations are not met, which poses a potential threat to the long-run effectiveness of conventional price-based demand response programs. There is also a risk that users who primarily hold non-financial motives may be discouraged to engage in demand side response if monetary savings is the key selling point of demand response programs. Policymakers, professionals and researchers should explore these risks and alternative policies that address them, particularly policies that may be more appealing to users that hold non-financial motives to engage in demand side response. Doing so will be key to ensure that current and future demand side response policies are cost-efficient and effective, both today and tomorrow.

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  • 4938.
    Öhrlund, Isak
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Civil and Industrial Engineering, Industrial Engineering and Management.
    Schultzberg, Mårten
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Statistics.
    The relationship between peak electricity demand, peak to off-peak price ratio and enabling technology: A commentary to Arcturus 2.0: A meta-analysis of time-varying rates for electricity2022Other (Other academic)
    Abstract [en]

    In “Arcturus 2.0: A meta-analysis of time-varying rates for electricity”, Ahmad Faruqui, Sanem Sergici and Cody Warner present a meta-analysis of an impressive collection of studies on the impact of time-varying pricing on peak electricity demand. Based on their analysis, the authors claim to have identified a positive log-linear relationship between peak demand reduction and the peak to off-peak price ratio and that this relationship is moderated by enabling technologies. However, we believe that there are a number of methodological issues and possible biases in the analysis that need to be addressed before we can draw such conclusions.

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  • 4939.
    Öhrlund, Isak
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Civil and Industrial Engineering, Industrial Engineering and Management.
    Stikvoort, Britt
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Psychology.
    Schultzberg, Mårten
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Statistics.
    Bartusch, Cajsa
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Civil and Industrial Engineering, Industrial Engineering and Management.
    Rising with the sun?: Encouraging solar electricity self-consumption among apartment owners in Sweden2020In: Energy Research & Social Science, ISSN 2214-6296, E-ISSN 2214-6326, Vol. 64, article id 101424Article in journal (Refereed)
    Abstract [en]

    Studies suggest that householders who turn prosumers become more energy aware, change their pattern of electricity use and may even start to engage in other pro-environmental activities. However, few of these studies were equipped to investigate such causal relationships—mainly because most prosumers are inherently self-selected. However, as real estate companies and building owners have begun installing photovoltaics on their customers’ behalf, a new breed of non-self-selected prosumers is emerging, which presents new opportunities to address questions of causality and thus improve our understanding of the possible implications of a more prosumer-dense future. Using a sample of 54 apartment households with a shared rooftop PV installation, this article presents the first causal analysis on non-self-selected prosumers’ response to information about having become prosumers, what that means for themselves and the collective they are part of, how to self-consume solar electricity and why they should do so. Using a stepped wedge design and stratified randomization procedure we were able to design an experimental study with sufficient power. A panel regression model and various statistical analyses on pre and post treatment survey- and electricity use data were used to evaluate the intervention. In line with studies of self-selected prosumers, the self-reported measures suggest that householders have shifted the use of major appliances to increase their self-consumption. However, based on the electricity use data, we find no evidence of a such a shift and no indications of spillovers to other pro-environmental behaviours—highlighting the need to use multiple measures to assess behavioural change.

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  • 4940.
    Öhrlund, Jack
    et al.
    Mälardalen University, School of Business, Society and Engineering.
    Östman, Catrin
    Mälardalen University, School of Business, Society and Engineering.
    DIGITALIZATION IS HEATING UP THE BUSINESS MODEL: A degree project regarding the impact of digitalization on a business model canvas within district heating2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The purpose of this degree project is to analyze and investigate how digitalization will affect business modeling in the district heating business.

    The chosen approach to this degree project was an iterative, abductive method, in order to always use a feedback-analysis and to keep the project open for new findings. The interviews were a mix of a structured method and a qualitative approach. With the structured method, the findings from the interviews were similar and regarding the research topic, and the qualitative approach in some open questions led to matters that otherwise would have been unnoticed. The interviews were performed via e-mail, phone and through personal interviews.

    This degree project concluded that digitalization has an impact on business modeling in district heating. Digitalization will affect some elements in a major way, for example key resources that will be characterized by digitalization. The findings from this work showed that a business model operating in district heating in a time of digitalization should focus on three main parts: economy, environment and easy visualization. An optimization tool should focus on delivering a value that consist of these three, and the remaining elements should together contribute to that value proposition.

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    DIGITALIZATION IS HEATING UP THE BUSINESS MODEL
  • 4941.
    Öman, Martin
    Karlstad University.
    Elproduktion med användning av överskottsvärme från mjukpapperstillverkning2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In industry, around 20-50% of the energy supply is lost in the form of surplus heat. Stricter environmental restrictions and incentives for higher economic profitability lead to the development of technology to increase recovery of this excess heat.

     

    Valmet AB is a company that provides facilities including paper and cardboard products. They are interested in investigating the possibility of increasing energy efficiency for the use of recovered surplus heat from tissue production, where the waste heat was represents by wet flue gases coming from the drying equipment.

     

    The purpose of the study is to investigate the waste heat and how it is used for electricity production with an Organic Rankin Cycle. The heat recovery potential in the flue gases and the ideal work was set against the actual work that could be achieved with the Organic Rankin Cycle. Modeling and design was performed using the ChemCad simulation tool, using a simplified model that does not calculate the components sizes and costs. The focus is instead on thermodynamic behaviors, in which extracted work and efficiencies are used to measure performance.

     

    Simulations were performed with respect to three different operating instances with waste heat with different moisture content. For the Organic Rankine Cycle, six different working media were investigated; Butane, Isobutan, R123, R236EA, R245ca and R245fa.

     

    The study showed that a large heat recovery potential exists in wet flue gases in the form of latent heat. Operating conditions with higher moisture content resulted in latent heat being recovered at higher temperatures. Higher moisture content also resulted to a higher performance in the Organic Rankin Cycle. In latent heat recovery, the ORC also demonstrated highest performance, with Isobutan as the best working medium, which was also the most environmentally friendly.

     

    The pinch temperature between the waste heat and the working medium was found to be a parameter influencing the performance of the ORC, where an increase of the pinch of 15˚C leads to a reduction of the ORC net production by 38%. Further studies taking into account physical and economic constraints needs to be set against the technical results of the cycle to evaluate the ORC performance. 

  • 4942.
    Öncel, Melih
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Industrial Ecology. KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy and Climate Studies, ECS.
    Marion, Gonzalo
    KTH, School of Industrial Engineering and Management (ITM), Industrial Ecology. KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy and Climate Studies, ECS. Universitat Politecnica de Catalunya.
    Providing Sustainable Life-solutions with a Hybrid Micro-Power Plant in Developing Countries: an Assessment of Potential Applications2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Today, energy access is a significant challenge all over the world, particularly in African countries. At the same time, providing energy access is generally accepted as a way to promote sustainable development. In countries such as Uganda, lack of energy access is evident. In this country only 9% of households have access to electricity. About 87% of these households are located in rural and remote areas. Thus, off-grid rural electrification solutions are required to supply electricity services to a significant part of the population.The ultimate objective of this thesis is to propose a specific solution to cover basic energy needs of the rural population considering environmental, social and economic benefits. How can sustainable life solutions be provided in rural areas, by using the energy surplus from a decentralized small-scale biomass gasification power plant? The analysis used as a starting point the Green Plant Concept, which considers the design of a sustainable off-grid platform that produces energy to provide life solutions and also to excite local entrepreneurship in the rural sites where it is implemented. The concept implies participation of the private sector – a telecommunication company – which is a unique feature in the context of rural energization.To develop our analysis, a field trip has been conducted in Uganda, Africa, to answer sub-questions such as How to reach a cost-effective system? How to adapt a business oriented approach to the community’s life-style in order to be well accepted? How to foster the development of the area by having a positive socio-economic impact on society? How to create an environmental friendly solution? How to achieve the maximum efficiency in terms of reusing waste? Tools such as Multi Criteria Analysis (MCA) and SWOT analysis were used to interpret collected information and identify impacts of the suggested solutions.The research has shown the great potential of the Green Plan Concept. We conclude by selecting three applications that can enhance the provision of basic energy needs while creating benefits for the stakeholders involved in the process: i) Mini-Grid solutions, ii) Battery Charging Stations and iii) Heat Pipe Exchangers. We also highlighted the relevance of bringing, in addition to appropriated technologies, different stakeholders together, considering their common interests.The research is finalized by estimating the payback period based on the current and expected energy consumption and the capital investment related to the suggested applications. It is important to highlight that the payback time estimations do not include the participation of the telecom companies. This means that the estimated payback period of 7 years could be significantly reduced by the inclusion of this stakeholder.

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  • 4943.
    Örarbäck, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Självkörande fordon: En analys av energianvändning och kapacitet2015Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Self-driving cars are soon to become a reality to the commercial market. A self-driving car does not have a human operator, which enables some interesting characteristics. The main benefits are considered to be:

    • The number of accidents and traffic jams should be reduced.
    • Enhanced comfort.
    • Energy usage could be decreased while capacity could be increased.

    This study concerns the causes for improved energy efficiency. The reason for improved energy efficiency is mainly because of the variation in terms of acceleration, braking and distance holding are reduced. The vehicles are more intelligent and can work together as a unity. There are reasons to believe that self-driving cars will first operate in highway conditions. The study has therefore tried to estimate what the potential benefits could be in terms of energy usage and capacity when comparing two sets of traffic flows in such an environment. One set of traffic flow was symbolized by self-driving cars, and one set was composed by conventional vehicles. With the settings and conditions defining the simulations in this study one can expect positive effects in both in energy usage and capacity with a traffic flow symbolized by self-driving cars. When comparing the two sets, with an increasing traffic flow from non-congestion up to congestion, the results showed energy savings around 10 percent with self-driving cars. 

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  • 4944.
    Östangård, Louise
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Reactivity Analysis of Nuclear Fuel Storages: The Effect of 238U Nuclear Data Uncertainties2013Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The aim of this master thesis work was to investigate how the uncertainties in nuclear data for 238U affects the uncertainty of keff in criticality simulations for nuclear fuel storages. This was performed by using the Total Monte Carlo (TMC) method which allows propagation of nuclear data uncertainties from basic nuclear physics to reactor parameters, such as keff. The TMC approach relies on simulations with hundreds of calculations of keff with different random nuclear data libraries for 238U for each calculation. The result is a probability distribution for keff where the standard deviation for the distribution represents a spread in keff due to statistical and nuclear data uncertainties.

    Simulations were performed with MCNP for a nuclear fuel storage representing two different cases:  Normal Case and Worst Case. Normal Case represents a scenario during normal conditions and Worst Case represents accident conditions where optimal moderation occurs. In order to validate the MCNP calculations and the libraries produced with TMC, criticality benchmarks were used.

    The calculated mean value of keff for the criticality benchmark simulations with random libraries produced with TMC obtained a good agreement with the experimental keff for the benchmarks. This indicates that the libraries used in this this work were of good quality.

    The TMC method´s drawback is the long calculation time, therefore the new method, fast TMC, was tested.  Both fast TMC and original TMC were applied to the Normal Case. The two methods obtained similar results, indicating that fast TMC is a good option in order to reduce the computational time. The computer time using fast TMC was found to be significantly faster compared with original TMC in this work.

    The 238U nuclear data uncertainty was obtained to be 209 pcm for the Normal Case, both for original and fast TMC. For the Worst Case simulation the 238U nuclear data uncertainty was obtained to be 672 pcm with fast TMC. These results show the importance of handling uncertainties in nuclear data in order to improve the knowledge about the uncertainties for criticality calculations of keff

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  • 4945.
    Östin, Ronny
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Nair, Gireesh
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Energy performance and lessons learned from detailed measurement of a passive house preschool in cold climate2019In: Is efficient sufficient?: eceee 2019 Summer Study on energy efficiency: Abstracts, European Council for an Energy Efficient Economy (ECEEE), 2019, p. 1433-1442Conference paper (Refereed)
    Abstract [en]

    Public passive house buildings are rare in high northern latitudes. This study reports on extensive measurements and evaluations of the most northerly (640 N) built passive house preschool in Sweden. The two storied preschool, built in 2014, has a total heated floor area of 1407 m2. The building was certified according to the international passive house standard. The building has several smart solutions such as demand controlled ventilation of individual rooms and automatic solar shading system.

    Energy measurements conducted during 2017-2018 showed that the preschool annually uses 44.4 kWhm-2, which is approximately 25 % lower than the passive house requirement for energy demand. However, the annual specific space heating requirement of 15 kWhm-2 and the peak heat power demand of 10 Wm-2 were not fulfilled. This non-compliance was mainly due to excessive ventilation during the heating season which was found to have 2.7 times higher air changes than the requirement in the Swedish building code. Furthermore, the building was found to be over heated from the sun during several occasions in a year. For example, excessive indoor air temperatures in the range 28 – 31°C were found during summer.

    The study revealed that the default winter operation by turning off the ventilation system during nights and weekends is continued in other seasons as well. This practice was not a “smart” approach for the air handling units as it was found to be one of the reasons for high indoor temperatures during non-winter months. Also, a mismatch between the operation of the automatic shading device and the ventilation control units was noted.

    The investigation shows that smart technical solutions in buildings may not be able to deliver its’ promised results if such systems are not monitored, adjusted and carefully evaluated. The paper identifies areas that need attention to ensure that a public building built to passive house standard actually deliver the energy efficiency it promises.

  • 4946.
    Östlin, Olof
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Sjödén Havik, Mikaela
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Kalibrering och validering av en IDA ICE modell: Ett flerbostadshus från 1970-talets miljonprogram2020Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis is a case study carried out on a Million Homes Program (MHP) building in Andersberg owned by AB Galvegårdarna, whom are also the clients. Since MHPbuildings are poorly insulated and have major heat leaks, it is of great interest today to investigate any improvement measures as these buildings have a potential to reduce their energy use by 50 percent. This is possible with the help of the calibrated model in a building energy performance simulation (BEPS) tool, which is the purpose of developing in this thesis. Through a literature study, visit in the building and gathering protocols, drawings and measured data, a model could be built and calibrated in IDA Indoor Climate and Energy was started. Drawings and data were provided from AB Gavlegårdarna and site visits were made to supplement these by taking measurements of temperatures in the common areas. On site, the dimensions of the building were also measured to ensure that the building had not been upgraded since the assigned drawings were created. When all the information was considered to have been obtained, all data was entered into IDA ICE where a model of the building was also built up. For the thermal bridges, the COMSOL Multiphysics simulation tool was used to generate their individual linear heat loss coefficient which were used as input in the building model of IDA ICE. The calibrated model developed in this project turned out to have a deviation of 10 % against annual district heating energy. The simulated building heat loss coefficient differed with 19.6 % compared to the one produced with a newly developed energy signature method for the corresponding year which may be caused by errors in the simulation tools and uncertainty concerning immeasurable parameters. The final conclusion of this work was that the performance gap also occurred on this model developed in this work, which seems to be hard to avoid. During the site visit, water collections on the roof of the building were discovered which was a surprise to the authors as there were documents that said that the surface layer had been changed in 2015 and that there were indications that this could have significant consequences if not addressed which is mentioned in the chapter of discussion. Future work on why residents’ behavioral patterns are underestimated would be something to continue with in future studies in order to reduce the “performance gap” in BES models.

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  • 4947.
    Östlund, Christine
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Dimensionering och optimering av ett solcellssystem för en industribyggnad i Mellansverige: En simuleringsstudie2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    When converting to renewable energy systems, solar power as an energy source is a potential option; in order to achieve the climate and energy goal with 100% renewable energy production in year 2040. This is something the government try to achieve by making installation of solar cells more attractive through allowances such as subventions and tax reduction. The aim of this study was to analyze the effect of solar cell system on an industrial building in the midst of Sweden, in regard of economical-, technical- and climate related points of view. This was performed by replacing purchased electricity with locally produced electricity, where optimal circumstances for the solar power systems and the limits of the building has been taken into consideration during the dimensioning. With cost suggestions from a local authorized dealer the magnitude of the pay off time as a motivating factor was estimated. The local climate impact will be investigated through a litterature study, focusing on green house gas emissions. The dimensioning of the solar cell systems were based on empirical input from measurements in combination with documented data regarding the industrial building and simulated in the program Winsun PV. The study resulted in two different-sized systems with cost sheets that formed the basis for the calculated pay off time. System case 1 was dimensioned to keep the size of the nominal system effect to 255 kWp, this to avoid extra energy tax. The system gave an annual exchange of 228 MWh / year which gave the repayment period between 18 - 23 years. The system was simulated with an optimum angle of 39 ° in 15 ° azimuth direction of the modules. System case 2 was dimensioned to 1200 kWp in order to cover the effective usable surface of the roof, the system gave an annual exchange of 886 MWh / year and the repayment period was 22.5 - 25.1 years. The modules were simulated with the roof slope ± 4.7 ° in -15 ° azimuth direction. A further efficiency development for solar cell technology is required as well as an extended investment support from the County Administrative Board, to provide a more profitable exchange of solar cell systems in higher latitudes. If the solar cell system has a positive effect on the ecological footprint depends on where the solar cell is made and which electrical mix replaced by the produced solar energy.

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  • 4948.
    Östlund, Theo
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Civil and Industrial Engineering.
    Olsson, William
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Civil and Industrial Engineering.
    Kärrman, Simon
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Civil and Industrial Engineering.
    ​​​Små modulära reaktorer i Sverige – ett nuläge​​2023Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Sweden has long had the goal of phasing out its nuclear power. However, both public opinion and politics have shifted in response to the climate and energy crisis, which demands fossil-free energy production. At the same time, small modular reactors (SMRs) have begun to be developed, and several players in Sweden have started exploring this technology. SMRs are smaller versions of conventional nuclear reactors but built in a modular fashion. The advantage of modularity is that the reactors can be produced in series, easily maintained, and their smaller size allows for more flexible placement and lower initial investment. Based on the above, this study examines how current nuclear power actors in Sweden view the development of SMRs. 

    To answer this question, semi-structured interviews were conducted with representatives from Fortum, Sydkraft Sverige (Uniper), and Kärnfull Next, all of which are active in nuclear power in Sweden. The study shows that the actors see the biggest advantages of SMRs as their modularity, relatively low investment requirements, and more flexible placement, which enables more efficient utilization. However, they believe that the development of SMRs is heavily constrained by current legislation and licensing processes. These are designed to promote the limitation and decommissioning of conventional nuclear power, and according to the respondents, they make successful SMR development impossible. The consequence is that the regulatory framework is more restrictive towards SMRs and hampers the ability to leverage the advantages of SMRs over conventional nuclear power. Furthermore, the respondents believe that there is a skills shortage in nuclear power that will need to be addressed in order to successfully develop SMRs in Sweden. 

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  • 4949.
    Öztürk, Esma
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    WAKE INDUCED POWER DEFICIT ANALYSIS ON WIND TURBINES IN FORESTED MODERATELY COMPLEX TERRAIN USING SCADA DATA2018Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Over the last few decades, wind power has shown a continuous and significant developmentin the energy market globally. Having reached a certain level in both technologyand in dimensions, the role of optimizing wind turbines as well as wind farms hasbecome an additional aspect to future development and research. Since turbine wakescan cause significant power deficits within a farm, research in this area has the potentialfor large improvements in wind farm design.

    A wake is described as the downstream flow behind the rotor of an operating windturbine. The two main characteristics of wakes are a velocity (momentum) deficit and anincreased turbulence level. The velocity deficit behind the upwind turbine results in apower loss of the downstream turbines, whereas the higher turbulence causes additionalloads on the downstream turbines’ structures resulting in fatigue problems.

    The study of wakes is a complex topic, they are influenced by an interconnection of anumber of parameters like ambient wind speed and turbulence, atmospheric stabilityconditions (stable, unstable, and neutral), the turbines’ operational characteristics, andthe terrain properties.

    In order to assess the power deficits affected by wake interaction between turbines,an analysis can be realized by processing SCADA data of turbines in a wind farm. The collected data is treated by a comprehensive filtration process, excluding events of icing, curtailment, faults, etc. and by grouping into different atmospheric conditions, windspeed intervals and wind speed sectors. Finally, power deficit values, as a function ofwind direction, are calculated and quantified, and thereafter analyzed to assess the wakebehavior at different conditions for different cases.In this thesis, the wake-induced power deficit has been investigated in a specificstudy case for three pairs of two neighboring turbines in a forested moderately complexterrain using SCADA data. The production losses amounted between the range of 32% to 67% for the specific site with turbine spacing around 4D. The obtained results werepartially unsatisfactory, caused by the reasons of inaccurate wind direction values due toyaw misalignment issues and challenging separation into different stability conditions. Moreover, the power deficits showed a clear reduction of losses with increasing windspeed. A conclusion regarding the differences between stable and near neutral conditionscould not be determined from the data.

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  • 4950.
    Ülker, Muhammed Akif
    Gotland University, School of Culture, Energy and Environment.
    Balancing of Wind Power: Optimization of power systems which include wind power systems2011Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In the future, renewable energy share, especially wind power share, in electricity generation is expected to increase. Due to nature of the wind, wind power generation pattern includes uncertainties which affects the energy prices in the electricity markets.

    New simulations are needed for efficient planning process for the resources in the power systems to address the uncertainties in demand, generation, legal, economical and technical limitations.

    In this study, the aspects of planning process for wind power generation is described and some example scenarios are implemented with the help of MATLAB software.

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    Balancing of Wind Power - MSc Thesis in Wind Power Project Management Master Program_Muhammed Akif Ulker
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