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  • 251.
    Atif, Yacine
    et al.
    University of Skövde, School of Informatics. University of Skövde, Informatics Research Environment.
    Ding, Jianguo
    University of Skövde, School of Informatics. University of Skövde, Informatics Research Environment.
    Lindström, Birgitta
    University of Skövde, School of Informatics. University of Skövde, Informatics Research Environment.
    Jeusfeld, Manfred
    University of Skövde, School of Informatics. University of Skövde, Informatics Research Environment.
    Andler, Sten F.
    University of Skövde, School of Informatics. University of Skövde, Informatics Research Environment.
    Yuning, Jiang
    University of Skövde, School of Informatics. University of Skövde, Informatics Research Environment.
    Brax, Christoffer
    CombiTech AB, Skövde, Sweden.
    Gustavsson, Per M.
    CombiTech AB, Skövde, Sweden.
    Cyber-Threat Intelligence Architecture for Smart-Grid Critical Infrastructures Protection2017Conference paper (Refereed)
    Abstract [en]

    Critical infrastructures (CIs) are becoming increasingly sophisticated with embedded cyber-physical systems (CPSs) that provide managerial automation and autonomic controls. Yet these advances expose CI components to new cyber-threats, leading to a chain of dysfunctionalities with catastrophic socio-economical implications. We propose a comprehensive architectural model to support the development of incident management tools that provide situation-awareness and cyber-threats intelligence for CI protection, with a special focus on smart-grid CI. The goal is to unleash forensic data from CPS-based CIs to perform some predictive analytics. In doing so, we use some AI (Artificial Intelligence) paradigms for both data collection, threat detection, and cascade-effects prediction. 

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  • 252.
    Atzarakis, N.
    et al.
    School of Electrical and Computer Engineering , National Technical University of Athens , Greece.
    Kouveliotis Lysikatos, Iasonas
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electric Power and Energy Systems.
    Palaiogianis, F.
    School of Electrical and Computer Engineering , National Technical University of Athens , Greece.
    Vasilakis, A.
    School of Electrical and Computer Engineering , National Technical University of Athens , Greece.
    Tsekeris, D.
    School of Electrical and Computer Engineering , National Technical University of Athens , Greece.
    Hatziargyriou, N.
    School of Electrical and Computer Engineering , National Technical University of Athens , Greece.
    SMART energy communities: A case study for Greece2020In: IET Conference Publications, Institution of Engineering and Technology (IET) , 2020, no CP767, p. 136-139Conference paper (Refereed)
    Abstract [en]

    In this study, the authors investigate the economic feasibility of an energy community investing in renewable energy sources (RES). The estimation is based on the optimisation of the total annual average electricity costs of a typical study case that uses historical load and RES generation data and follows the directives of the Greek recent legislation for energy communities. The operation of a local energy market is compared with other available RES pricing mechanisms, such as self-consumption, feed-in-tariff and net metering.

  • 253.
    Auland, Clara
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Storskaligt logistiksystem för vätgastransport2021Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The energy transition is crucial to limit the global carbon dioxide emissions. Renewable energy sources like wind and solar are intermittent and we need to find ways to use the electricity surplus and store energy. Hydrogen is an energy carrier and has the potential to be a key to achieve a renewable energy system. The aim of the study is to investigate the feasibility for an economic and technical sustainable system for hydrogen distribution. The goal was to calculate transmission cost for different types of hydrogen transport. A profound literature study and external analysis was made in the beginning. Then two cases were selected in the northern part of Sweden. Based on the conditions, transport through pipeline, road transport and transport by rail were choosen.

    The results for transport by road suggests that very frequent transports are required to deliver the quantity in the cases taken up, which results in high costs. Distribution cost by rail implies high investment costs and there are no significant difference between distribution cost for the cases. Furthermore the results implies that pipeline has low operating costs for both cases and it also implies a difference between investments cost for the cases. The result also indicates that transmission cost by pipelines is cheaper than transmission cost for electricity.

    Which one is the best option depends on many different factors such as conditions at the location, electricity price, distance and the volume. There are uncertainties in the results for transport by road and by rail, which makes it difficult to conclude based on the current findings. The comparision between hydrogen and electricity should be seen as a rough estimate due to the uncertanties.

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  • 254.
    Aupke, Phil
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Seema,
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Theocharis, Andreas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Kassler, Andreas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Archer, Dan-Eric
    CheckWatt AB, Sweden.
    PV Power Production and Consumption Estimation with Uncertainty bounds in Smart Energy Grids2023In: 2023 IEEE International Conference on Environment and Electrical Engineering and 2023 IEEE Industrial and Commercial Power Systems Europe (EEEIC / I&CPS Europe), IEEE, 2023Conference paper (Refereed)
    Abstract [en]

    For efficient energy exchanges in smart energy grids under the presence of renewables, predictions of energy production and consumption are required. For robust energy scheduling, prediction of uncertainty bounds of Photovoltaic (PV) power production and consumption is essential. In this paper, we apply several Machine Learning (ML) models that can predict the power generation of PV and consumption of households in a smart energy grid, while also assessing the uncertainty of their predictions by providing quantile values as uncertainty bounds. We evaluate our algorithms on a dataset from Swedish households having PV installations and battery storage. Our findings reveal that a Mean Absolute Error (MAE) of 16.12W for power production and 16.34W for consumption for a residential installation can be achieved with uncertainty bounds having quantile loss values below 5W. Furthermore, we show that the accuracy of the ML models can be affected by the characteristics of the household being studied. Different households may have different data distributions, which can cause prediction models to perform poorly when applied to untrained households. However, our study found that models built directly for individual homes, even when trained with smaller datasets, offer the best outcomes. This suggests that the development of personalized ML models may be a promising avenue for improving the accuracy of predictions in the future.

  • 255.
    Averfalk, Helge
    et al.
    Halmstad University, School of Business, Engineering and Science, The Rydberg Laboratory for Applied Sciences (RLAS).
    Ingvarsson, Paul
    ÅF, Division Industry, Stockholm, Sweden.
    Persson, Urban
    Halmstad University, School of Business, Engineering and Science, The Rydberg Laboratory for Applied Sciences (RLAS).
    Gong, Mei
    Halmstad University, School of Business, Engineering and Science, The Rydberg Laboratory for Applied Sciences (RLAS).
    Werner, Sven
    Halmstad University, School of Business, Engineering and Science, The Rydberg Laboratory for Applied Sciences (RLAS).
    Large heat pumps in Swedish district heating systems2017In: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 79, p. 1275-1284Article in journal (Refereed)
    Abstract [en]

    Power-to-heat solutions like heat pumps and electric boilers are foreseen to be possible future tools to stabilise international power markets with high proportions of variable power supply. Temporary low cost electricity can be used for heat generation at times with high availability of wind and solar power through substitution of ordinary heat supply, hence contributing to increased energy system sustainability. Power-to-heat installations in district heating systems are competitive due to low specific investment and installation costs for large electric boilers, heat pumps, and heat storages. Several large-scale heat pumps were installed in Swedish district heating systems during the 1980s, since a national electricity surplus from new nuclear power existed for some years. The aim of this paper is to summarise the accumulated operation experiences from these large Swedish heat pumps to support and facilitate planning of future power-to-heat solutions with heat pumps in district heating systems. Gained experiences consider; installed capacities, capacity utilisation, heat sources used, refrigerant replacements, refrigerant leakages, and wear of mechanical components. The major conclusion is that many of the large thirty-year-old heat pumps are still in operation, but with reduced capacity utilisation due to internal competition from waste and biomass cogeneration plants in the district heating systems.

  • 256.
    Averfalk, Helge
    et al.
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS), Energiteknik.
    Ingvarsson, Paul
    ÅF, Division Industry, Stockholm, Sweden.
    Persson, Urban
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS), Energiteknik.
    Werner, Sven
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS), Energiteknik.
    On the use of surplus electricity in district heating systems2014In: Proceedings from the 14th International Symposium on District Heating and Cooling: September, 6-10, 2014: Stockholm, Sweden / [ed] Anna Land, Stockholm: Swedish District Heating Association , 2014, p. 469-474Conference paper (Refereed)
    Abstract [en]

    Maintained balance between supply and demand is a fundamental prerequisite for proper operation of electric power grids. For this end, power systems rely on accessibility to various balancing technologies and solutions by which fluctuations in supply and demand can be promptly met. In this paper, balancing approaches in the case of surplus electricity supply, due to long-term, seasonal, or short-term causes, are discussed on the basis mainly of compiled experiences from the Swedish national power grid. In Sweden, a structural long-term electricity surplus was created in the 1980s when several new nuclear plants were commissioned and built. One of four explicit domestic power-to-heat solutions initiated to maximize the utilization of this surplus electricity, as export capacities were limited, was the introduction of large scale electric boilers and compressor heat pumps in district heating systems. In retrospective, this solution not only satisfied the primary objective by providing additional electricity demand to balance the power grid, but represents today – from an energy systems perspective – a contemporary example of increased system flexibility by the attainment of higher integration levels between power and heat sectors. As European power supply will be reshaped to include higher proportions of fluctuating supply technologies (e.g. wind and solar), causing occasional but recurring short-term electricity surpluses, the unique Swedish experiences may provide valuable input in the development of rational responses to future balancing challenges. The main conclusions from this study are that district heating systems can add additional balancing capabilities to power systems, if equipped with electrical heat supply technologies, hereby contributing to higher energy system flexibility. Consequently, district heating systems also have a discrete but key role in the continued integration of renewable intermittent power supply technologies in the future European energy system.

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    On the use of surplus electricity in district heating systems
  • 257.
    Averfalk, Helge
    et al.
    Halmstad University, School of Business, Innovation and Sustainability, The Rydberg Laboratory for Applied Sciences (RLAS).
    Persson, Urban
    Halmstad University, School of Business, Innovation and Sustainability, The Rydberg Laboratory for Applied Sciences (RLAS).
    Low‐temperature excess heat recovery in district heating systems: The potential of European Union metro stations2020In: Book of Abstracts: 6th International Conference on Smart Energy Systems / [ed] Henrik Lund, Brian Vad Mathiesen, Poul Alberg Østergaard & Hans Jørgen Brodersen, 2020, p. 34-34Conference paper (Other academic)
    Abstract [en]

    This paper presents an assessment of the excess heat recovery potential from EU metro stations. The assessment is a sub-study on low temperature recovery opportunities, explored in the H2020 ReUseHeat project, and consists of spatial mapping of 1994 underground stations with quantitative estimates of sensible and latent heat, monthly and annually, attainable in rejected platform ventilation exhaust air. Being a low-temperature source, the assessment conceptually anticipates recovery of attainable heat with compressor heat pumps to facilitate the temperature increase necessary for utilisation in district heating systems. Further, the paper explores the influence on useful excess heat volumes from low-temperature heat recoveries when distributed at different temperature levels. The findings, which distinguishes available (resource) and accessible (useful) excess heat potentials, indicate an annual total EU28 available potential of ~21 PJ, characterised by a certain degree of seasonal temporality, and corresponding accessible potentials of ~40 PJ per year at 3rd generation distribution, and of ~31 PJ at anticipated 4th generation conditions. Despite lower accessible volumes, utilisation in 4th generation systems are naturally more energy efficient, since relatively less electricity is used in the recovery process, but also more cost-effective, since heat pumps, at lower temperatures, can be operated at capacities closer to design conditions and with less annual deviations.

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    Conference_presentation
  • 258.
    Awais, Fawad
    et al.
    University of Gothenburg, Sweden.
    Flodén, Jonas
    University of Gothenburg, Sweden.
    Svanberg, Martin
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Logistic characteristics and requirements of Swedish wood biofuel heating plants2021In: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 138, article id 110650Article in journal (Refereed)
    Abstract [en]

    The demand for wood biofuel for district heating plants and combined heat and power plants (CHPs) has increased, caused by an increase in both the number and size of CHPs. This places large demands on the logistics system supplying these plants with fuel, with a particular interest in the use of alternative modes of transport such as rail and sea. The aim of this paper is to identify the industry actors’ requirements, constraints, and preferences regarding the wood-biofuel supply chain and to identify the logistical challenges this entails, as well as how this impacts the opportunity for an increased use of alternative transport solutions. A survey was sent to all Swedish CHPs, combined with six interviews with transport companies, terminal operators, and forest companies. The study shows that the industry has a local focus that limits potential logistics and sourcing solutions. It is also challenged by urban sprawl, with expanding residential areas close to the CHPs putting further constraints on the operations. Significant variations in fuel demand, depending on unpredictable outside temperature and seasonal variation, is a further challenge. The low density of the fuel has a negative impact on transport costs and introduces a trade-off between chipping close to the forest to increase density versus more efficient chipping at the CHP. Intermodal transport only used by large plants, driven by a shortage of local fuel. © 2020 The Authors

  • 259.
    Awan, Muhammad Rizwan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Feasibility Study of Vertical Axis wind turbines in Urban areas of Sweden2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
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    Muhammad Rizwan Awan EGI-2013-126MSC EKV981
  • 260.
    Awan, Muhammad Rizwan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Riaz, Fahid
    Nabi, Zahid
    Analysis of conditions favourable for small vertical axis wind turbines between building passages in urban areas of Sweden2017In: International Journal of Sustainable Energy, ISSN 1478-6451, E-ISSN 1478-646X, Vol. 36, no 5, p. 450-461Article in journal (Refereed)
    Abstract [en]

    This paper presents the analysis of installing the vertical axis wind turbines between the building passages on an island in Stockholm, Sweden. Based on the idea of wind speed amplification due to the venture effect in passages, practical measurements were carried out to study the wind profile for a range of passage widths in parallel building passages. Highest increment in wind speed was observed in building passages located on the periphery of sland as wind enters from free field. Wind mapping was performed in the island to choose the most favourable location to install the vertical axis wind turbines (VAWT). Using the annual wind speed data for location and measured amplification factor, energy potential of the street was calculated. This analysis verified that small vertical axis wind turbines can be installed in the passage centre line provided that enough space is provided for traffic and passengers.

  • 261.
    Axelsson, Sebastian
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Utredning av en potentiell installation av FTX-ventilation med värmeåtervinning2018Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The main purpose of this degree project is to study and investigate a specific existing building to contribute to promoting a sustainable future on a larger scale. At the same time, shows that in many cases it can also be profitable to invest in a new energy-efficient system. After studying the structure and existing system of the building, it was found that a new ventilation system would be relevant.

    The building holds 83 apartments on a total area of 5 474 m2 and is located in northern part of Sweden, where temperatures of -30 °C are commen during winter time. The property is currently run by an exhaust air system for transporting consumed air, fresh air flows through outside valves directly into the recidence. Because the property is located in a place where cold outdoor temperatures occur many times a year, it's unlikely to transport cold air directly into the dwelling without preheating. This means that the current district heating consumption of the radiators will achieve unacceptable high values to maintain a good indoor envirement.

    The project that has been implemented shows that there are primarily an opportunity to install an FTX system in the homes. In many cases, there are a lack of space that contradicts an installation. Apart from the space, the result shows that district heating can be reduced by up to 600 MWh per year. This would mean a saving of 411 KSEK per year for the entire property. The cost of the required material is estimated at approximately 3.1 MSEK. This means that the investment is repaid after about 7-8 years. The figures mentioned above correspond to the material package that is reported in the report's results and assumes that existing air ducts present in the accommodation today remain but expanded. The design of the proposal presented is based on a balanced ventilation with heat recovery (80 %) with separate units for each apartement.

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    Master Thesis
  • 262.
    Axelsson, Tobias
    Karlstad University.
    Stöd till energi- och klimatrådgivnin: Solceller samt energilagring med batterier och svänghjul2019Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    There are many paths towards a more sustainable future. One way is to be more efficient with the use of energy in our daily lives. Another way is to work towards an increasing share of renewable energy in the energy mixture. The municipalities in Sweden has since the late 70s employed experts to provide the citizens with energy advice. This study was performed to provide additional information and inspiration for the benefit of these energy and climate advisors. In this article the author has conducted a literature compilation/review regarding the subject solar PV since the advisors deal with a lot of questions regarding this subject. The literature compilation also includes the subject energy savings and energy storage. An internet-based survey and a focus group discussion are also included to improve understanding of how the respondents think and feel about solar PV and their energy habits. It turns out to be hard to find information that eases the purchase and installation of solar panels. The advisors should make use of the people who already uses solar power in the municipally. These people can provide information regarding dealers and contractors as well as provide exposure for solar PV itself. The results also show that a lot of people cannot afford to invest in solar power. Therefore, it is important not to neglect advice regarding energy savings. Especially since it turns out that most respondents care about their environmental footprint and are willing to make changes, but are not always sure of what to do. This seems to indicate that general energy saving tips that reaches a lot of people would be effective. As an energy and climate advisor you should also try to help people to help themselves get more and better feedback regarding their energy usage. To remind the inhabitance of the municipally that regular maintenance should be performed on the home itself as well as on certain devices seems to be an effective strategy. Lastly people would benefit from simple statistics to help them get a better understanding for which devices uses the most energy. This would give them a knowledge foundation that would ease future device investments. To add further to this paper, a life-cycle costing analysis for a typical Swedish home equipped with solar PV and energy storage is used to determine if a hybrid energy storage system (mechanical and chemical) can rival more traditional storage solutions. The most promising hybrid system is 30 kWh divided in a 3:17 ratio between flywheel and batteries. However, from an economic standpoint battery storage still outperformed the system with a small margin.

  • 263.
    Ayedi, Omar
    Karlstad University, Faculty of Technology and Science, Avdelningen för energi-. miljö- och byggteknik.
    Energieffektiv torkning av kläder: en studie av torktumlare med varm- respektive kallvattenanslutning2011Independent thesis Basic level (professional degree), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    Tumble dryers and drying cabinets have to a large extent replaced the traditional way of drying clothes outdoors. They are faster, more convenient, require less space and can be operated regardless of weather conditions. This replacement has significantly increased residential energy consumption, due to the fact that tumbles dryers consume large amounts of electrical energy. In the USA 9 % of the households electric energy is consumed when drying clothes. Over 4 million tumble dryers are sold in Europe each year and 20 % of the residential electricity consumption in Sweden is used drying and washing clothes. Tumble dryers are also utilized in the industrial sector, but industrial dryers are not considered in this study.Increasing energy costs contributes to the public’s awareness and desire to cut their energy consumption. The aim of this study is to increase the energy efficiency and drastically reduce electric power use of tumble dryers.There are two main types of tumble dryers available on the market; the open cycle tumble dryer and the closed cycle tumble dryer. The open cycle tumble dryer is often attached to the ventilation system and thereby it evacuates its exhaust air. The closed cycle tumble dryer condenses the water from the air before it recirculates it.To increase the energy efficiency and reduce electric power use of tumble dryers, two separate studies were made. One on a water cooled closed cycle tumble dryer and one on a hot water heated open cycle tumble dryer. Both tumble dryers where rebuild and originated from the same tumble dryer. The tumble dryer that both studies originated from was a conventional air cooled closed cycle tumble dryer. The tumble dryer is made by Asko Cylinda AB.The results reveal that the water cooled closed cycle tumble dryer does not have greater energy efficiency than the conventional air cooled closed cycle tumble dryer. However the drying time was reduced by 37 %.The result also reveals that the hot water heated open cycle tumble dryer cuts the electric consumption by 93 % and improves the energy efficiency by 53 % compared to the conventional air cooled closed cycle tumble dryer. On the other hand the drying time increases by 9 %.

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  • 264.
    Ayele, Getnet Tadesse
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. GEPEA, IMT Atlantique, Dept Energy Syst & Environm, F-44307 Nantes, France.
    Mabrouk, Mohamed Tahar
    GEPEA, IMT Atlantique, Dept Energy Syst & Environm, F-44307 Nantes, France..
    Haurant, Pierrick
    GEPEA, IMT Atlantique, Dept Energy Syst & Environm, F-44307 Nantes, France..
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Lacarriere, Bruno
    GEPEA, IMT Atlantique, Dept Energy Syst & Environm, F-44307 Nantes, France..
    Santarelli, Massimo
    Politecn Torino, Dipartimento Energet, Corso Duca Abruzzi 24, I-10129 Turin, Italy..
    Electrified district heating networks: a thermo-economic optimisation based on exergy and energy analyses2021In: International Journal of Exergy, ISSN 1742-8297, E-ISSN 1742-8300, Vol. 35, no 1, p. 100-131Article in journal (Refereed)
    Abstract [en]

    This paper presents a thermo-economic optimisation of an electrified district heating network consisting of wind power plant, gas-fired combined heat and power plant and heat pumps. The load flow problem of the resulting multi-energy system is formulated by considering all physical and operating parameters in both of the electricity and heat distribution networks. First, energy and exergy analyses are applied to identify and isolate lossy branches of a meshed heating network. This is followed by the optimal placement of heat pumps. Finally, supply and return temperatures are optimised. Particle swarm optimisation technique is implemented in order to find the best place of heat pumps, their economical dispatch and optimal temperature profile of the district heating network. Results show that up to 59.12% of the distribution heat loss and 9.37% of the operating cost can be saved by following a step-by-step methodology discussed in this paper.

  • 265.
    Ayotte, John
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control.
    Dynamic positioning of a semi-submersible, multi-turbine wind power platform2015Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    As a growing market for offshore wind power has created a niche for deep-water installations, offshore floating wind solutions have become more and more viable as a renewable energy source. This technology is currently in development and as with many new technologies, many traditional design methods are found lacking. In the multi-turbine platform design investigated, turbine units are placed closely together to conserve material use and reduce cost, however with such tightly spaced turbines; wake interaction poses a threat to the productivity and the lifespan of the installation. In order to fully capitalize on the substantial increase in available wind energy far at sea, it is important that these floating parks operate in an optimal way. The platform investigated in this report sports 3, 6MW turbines which must be positioned such that wake interference is minimized; the platform must always bear a windward heading. 

    Maneuvering ocean going vessels has been practiced using automated dynamic positioning systems in the gas and oil industry for over 50 years, often employing submerged thrusters as a source of propulsion. These systems are mostly diesel powered and require extra operational maintenance, which would otherwise increase the cost and complexity of a floating wind farm. In this paper, it is suggested that the wind turbines themselves may be used to provide the thrust needed to correct the platform heading, thus eliminating the practical need for submerged thrusters. By controlling the blade pitch of the wind turbines, a turning moment (torque) can be exerted on the platform to correct heading (yaw) relative wind direction. Using the Hexicon H3-18MW platform as a starting point; hydrodynamic, aerodynamic and electromechanical properties of the system are explored, modeled and attempts at model predictive control are made. Preliminary results show that it is possible to control the H3’s position (in yaw) relative the wind using this novel method.

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    Dynamic positioning of a semi-submersible, multi-turbine wind power platform
  • 266.
    Ayoub, Ali
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    The role of nuclear energy2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The societies in Europe have developed enormously in recent decades, and this in turn has led to a greater need for electricity. Large parts of society are electrified and are now one of the most essential parts of the system. Electrification has resulted in more energy sources, which in turn has resulted in even greater emissions that harm the environment. Recently, the world has experienced various climate changes because of the industrialization of society.

    Therefore, it is essential today to phase out the energy sources that have a large negative impact on the environment to replace them with environmentally friendly ones. Greenhouse gas emissions are the main cause of climate change and will lead to increased extreme weather, such as droughts, floods, heat waves, and storms. This in turn will negatively affect societies, economies, and ecosystems. The rising global temperature leads to melting glaciers and results in rising sea levels. Climate change is affecting ecosystems all over the world and is also threatening biodiversity. Nuclear power has long been a debatable topic because of a couple of accidents in history, which have had devastating consequences on climate and society. In contrast, nuclear power plants are one of the energy sources that have no contribution to emissions during their operation. This work is a literature study which is based on a case study where the results are built on a comparison of nuclear power plants, coal power plants, and wind power plants based on carbon dioxide emissions, air pollution, land use, and waste management. The aim is to answer the question of whether nuclear power plants are an environmentally friendly alternative based on the results reported in the study.

    The result shows that nuclear power has a significant role in the Swedish and European electricity grid, as it is a foundation for a stable electricity grid. The result also shows that nuclear power plants are an environmentally friendly alternative. The study also shows that future research is essential and has significance. The most common argument against nuclear power plants is the risks in the event of an accident and what consequences they can have.

    Future research may mean safer operation of nuclear power plants and a reduction in the risk of accidents. The study shows that the survival of nuclear power plants has a significant role and is vital in sustainable work.

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  • 267.
    Azad, Mohammad
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Evaluation of an Energy System for multi-family houses with Combination of Exhaust Air Heat Pump and PV: Case Study: Demonstration Building of The EU Energy Matching Project, Sweden-Ludvika2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis investigated application of the heat recovery ventilation using an exhaust air heat pump and a roof top photovoltaic (PV) system for a group of three multi-family houses located in Ludvika, Sunnansjö. The buildings in the existing condition have mechanical ventilation and a centralized heating system consists of a pellet boiler as the main source and an oil boiler as back up.

    Exhaust air heat pump (EAHP) has been known by the previous relevant researches as an effective solution to promote the energy efficiency in the buildings. Furthermore, reduction in PV cost has made the PV as a financially viable option to be contributed in supplying electricity demand.

    In this respect, this thesis aimed to calculate the potential of energy saving in the case study using the combination of EAHP and PV. For this purpose, the buildings and the proposed energy system were simulated to enable the comparison of energy demand before and after the renovation. The simulation was gradually progressed through several phases and each stage created the prerequisites of the next.

    Since the buildings were relatively similar in terms of boundary conditions, one of the buildings were initially modeled and the concluded space heating (SH) demand was extrapolated to the three buildings scope. The simulation of the building was done using 3dimensional thermal model offered by Trnsys3d. The primary results were also calibrated against the available annual fuel consumption data. In the second phase, a pre-developed TRNSYS model of the energy system was completed using the result of previous step as the total SH demand as well as the estimated domestic hot water (DHW) consumption from a stochastic model. This simulation produced the electricity demand profile of the heat pump when the heat pump provided the total heat demand. Subsequently, the electricity consumption of the flats and operational equipment were estimated using stochastic model and available monthly measurement, respectively.

    Since the feasibility and optimal placement of 74 𝑘𝑊 PV modules offered for these buildings had been already examined by the author in another study, the final simulation were performed in an hourly basis considering PV production and total electricity demand; i.e. EAHP, flats consumption and operational equipment.

    The results of the simulation showed that 21 % of total electricity demand during a year could be supplied by the proposed PV system even without any electrical storage, whereas 74 % of total yearly PV production is consumed by the local loads. The results also proved that removing old inefficient oil boiler and supplementing the pellet boiler with the combination of EAHP and PV could mitigate the annual purchased energy (including electricity and pellet) by approximately 40 % compared to the current condition.

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  • 268.
    Azar, Christian
    et al.
    Chalmers Univ Technol, Dept Phys Resource Theory, SE-41296 Gothenburg, Sweden.
    Lindgren, Kristian
    Chalmers Univ Technol, Dept Phys Resource Theory, SE-41296 Gothenburg, Sweden.
    Larson, Eric
    Princeton Environmental Inst., Guyot Hall, Princeton Univ., Princeton, NJ 08540, United States.
    Möllersten, Kenneth
    International Institute for Applied Systems Analysis, A-2361 Laxenburg, Schlossplatz 1, Austria.
    Carbon capture and storage from fossil fuels and biomass -: Costs and potential role in stabilizing the atmosphere2006In: Climatic Change, ISSN 0165-0009, E-ISSN 1573-1480, Vol. 74, no 1-3, p. 47-79Article in journal (Refereed)
    Abstract [en]

    The capture and storage of CO2 from combustion of fossil fuels is gaining attraction as a means to deal with climate change. CO2 emissions from biomass conversion processes can also be captured. If that is done, biomass energy with CO2 capture and storage (BECS) would become a technology that removes CO2 from the atmosphere and at the same time deliver CO2-neutral energy carriers (heat, electricity or hydrogen) to society. Here we present estimates of the costs and conversion efficiency of electricity, hydrogen and heat generation from fossil fuels and biomass with CO2 capture and storage. We then insert these technology characteristics into a global energy and transportation model (GET 5.0), and calculate costs of stabilizing atmospheric CO2 concentration at 350 and 450 ppm. We find that carbon capture and storage technologies applied to fossil fuels have the potential to reduce the cost of meeting the 350 ppm stabilisation targets by 50% compared to a case where these technologies are not available and by 80% when BECS is allowed. For the 450 ppm scenario, the reduction in costs is 40 and 42%, respectively. Thus, the difference in costs between cases where BECS technologies are allowed and where they are not is marginal for the 450 ppm stabilization target. It is for very low stabilization targets that negative emissions become warranted, and this makes BECS more valuable than in cases with higher stabilization targets. Systematic and stochastic sensitivity analysis is performed. Finally, BECS opens up the possibility to remove CO2 from the atmosphere. But this option should not be seen as an argument in favour of doing nothing about the climate problem now and then switching on this technology if climate change turns out to be a significant problem. It is not likely that BECS can be initiated sufficiently rapidly at a sufficient scale to follow this path to avoiding abrupt and serious climate changes if that would happen.

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  • 269.
    Azar, Christian
    et al.
    Chalmers Univ Technol, Dept Phys Resource Theory, S-41296 Gothenburg, Sweden.
    Lindgren, Kristian
    Chalmers Univ Technol, Dept Phys Resource Theory, S-41296 Gothenburg, Sweden.
    Obersteiner, Michael
    Int Inst Appl Syst Anal, A-2361 Laxenburg, Austria.
    Riahi, Keywan
    Int Inst Appl Syst Anal, A-2361 Laxenburg, Austria.
    van Vuuren, Detlef P.
    Netherlands Environm Assessment Agcy, NL-3729 AH Bilthoven, Netherlands.
    den Elzen, K. Michel G. J.
    Netherlands Environm Assessment Agcy, NL-3729 AH Bilthoven, Netherlands.
    Möllersten, Kenneth
    Int Inst Appl Syst Anal, A-2361 Laxenburg, Austria.
    Larson, Eric D.
    Climate Cent Inc, Princeton, NJ 08542 USA.
    The feasibility of low CO2 concentration targets and the role of bio-energy with carbon capture and storage (BECCS)2010In: Climatic Change, ISSN 0165-0009, E-ISSN 1573-1480, Vol. 100, no 1, p. 195-202Article in journal (Refereed)
    Abstract [en]

    The United Nations Framework Convention on Climate Change (UNFCCC 1992) calls for stabilization of atmospheric greenhouse gas (GHG) concentrations at a level that would prevent dangerous anthropogenic interference with the climate system. We use three global energy system models to investigate the technological and economic attainability of meeting CO2 concentration targets below current levels. Our scenario studies reveal that while energy portfolios from a broad range of energy technologies are needed to attain low concentrations, negative emission technologies-e.g., biomass energy with carbon capture and storage (BECCS)-significantly enhances the possibility to meet low concentration targets (at around 350 ppm CO2).

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  • 270.
    Azeem, Muhammad
    et al.
    University of Engineering and Technology, Pakistan.
    Malik, Tahir Nadeem
    HITECH University, Pakistan.
    Muqeet, Hafiz Abdul
    Punjab Tianjin University of Technology Lahore, Pakistan.
    Hussain, Muhammad Majid
    Heriot-Watt University, United Kingdom.
    Ali, Ahmad
    Bahria University, Pakistan.
    Khan, Baber
    International Islamic University, Pakistan.
    Rehman, Atiq Ur
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Combined Economic Emission Dispatch in Presence of Renewable Energy Resources Using CISSA in a Smart Grid Environment2023In: Electronics, E-ISSN 2079-9292, Vol. 12, no 3, article id 715Article in journal (Refereed)
    Abstract [en]

    The geographically spatial and controlled distribution of fossil fuel resources, catastrophic global warming, and depletion of fossil fuel resources have forced us to integrate zero- or low-emissions energy resources, such as wind and solar, in the generation mix. These renewable energy resources are unexhausted, available around the globe, and free of cost. The advancement in wind and solar technologies has caused an appreciable decrease in installed the and global levelized costs of electricity via these sources. Therefore, the penetration of renewable energy resources in the generation mix can provide a promising solution to the above-mentioned problems. The aim of simultaneously reducing fuel consumption in terms of “Fuel Cost” and “Emission” in thermal power plants is called a combined economic emission dispatch problem. It is a combinatorial and multi-objective optimization problem. The solution of this problem is to allocate the load demand and losses on the committed units in such way that the overall costs of the generation and emission of thermal units are reduced, while the legal bounds (constraints) are met. It is a highly non-linear and complex optimization problem. The valve-point loading effect makes this problem non-convex. The addition of renewable energy resources (RERs) adds more complexities to this problem because they are intermittent. In this work, chaotic salp swarm algorithms (CISSA) are used to solve the combined economic emission dispatch problem. Chaos is used as an alternative to randomization for the tuning of the control variable to improve the trait of obtaining global extrema. Different test cases having different combinations of thermal, solar, and wind units are solved using the proposed algorithm. The results show the superiority of this study in comparison to the existent research results in terms of the cost of generation and emissions.

  • 271. Aziz, M.
    et al.
    Zaini, Ilman Nuran
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Production of hydrogen from algae: Integrated gasification and chemical looping2017In: Proceedings of the 9th International Conference on Applied Energy, Elsevier, 2017, Vol. 142, p. 210-215Conference paper (Refereed)
    Abstract [en]

    Due to their high potential and beneficial characteristics, algae is considered as very promising energy source in future. In this study, an integrated conversion system of algae to hydrogen is proposed with the objective of high total energy conversion efficiency. The proposed system mainly covers algal drying, gasification, and chemical looping. To facilitate optimum heat circulation throughout the proposed system, enhanced process integration is adopted. It combines exergy recovery and process integration technologies in order to achieve a wasted energy, hence the total energy efficiency can be improved significantly. In the proposed system, to convert algae to hydrogen, steam gasification and syngas chemical looping are integrated as the main conversion. Iron oxide is employed as the oxygen carrier, and is circulated among the reactors in the chemical looping module. Process modeling and calculation is performed using ASPEN Plus, and the total energy efficiency, including hydrogen production and power generation, is evaluated. Several operating parameters including target moisture content in drying, steam-to-biomass ratio in gasification, and chemical looping pressure, are observed. From the results, it is shown that the proposed system is potential to convert algae to hydrogen with high total energy efficiency, which is higher than 70%. Both target moisture content and steam-to-biomass ratio influence strongly the total energy efficiency. On the other hand, chemical looping pressure show insignificant effect to total energy efficiency.

  • 272.
    Azizi, Ali
    et al.
    Iran University of Science and Technology, Department of Electrical Engineering, Tehran, Iran.
    Jahromi, Mehdi Zareian
    Amirkabir University of Technology, Department of Electrical Engineering, Tehran, Iran.
    Dehghanian, Pooria
    Texas A&M University, Department of Electrical and Computer Engineering, College Station, TX, USA.
    Chamorro Vera, Harold Rene
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electric Power and Energy Systems.
    Mirez, Jorge
    Universidad Nacional de Ingeniería (UNI), Group of Mathematical Modeling and Numerical Simulations, Lima, Peru.
    Sood, Vijay K.
    Ontario Tech University, Department of Electrical, Computer and Software Engineering, Oshawa, ON, Canada.
    Decentralized Multi-Objective Energy Management With Dynamic Power Electronic Converters and Demand Response Constraints2023In: IEEE Access, E-ISSN 2169-3536, Vol. 11, p. 146297-146312Article in journal (Refereed)
    Abstract [en]

    Energy management plays a pivotal role in enhancing the economic efficiency of power systems. However, it is noteworthy that a substantial number of microgrids (MGs) exhibit inherent unbalances that impose a range of critical issues, including voltage instability, elevated losses, power quality violations, safety concerns, and inefficiencies in energy management. Fast-acting power electronic converters present a relevant and efficacious solution for balancing such complex networks. This paper investigates the application of such converters within the realm of 3-phase unbalanced networks, wherein the proposed algorithm not only ameliorates network imbalances but also yields substantial reductions in operational costs, power losses, voltage deviations, and emissions. Demand response (DR) program has been applied to the model to enhance the system efficiency. The uncertainty about electric demand and renewable energy sources is considered in the simulation model for precise results. By implementing DR programs and penetrating distributed generators (DGs), the proposed model has been shown to reduce network losses and operation costs by 23% and 80%, respectively. Also, the total up-to-down voltage deviation of the voltage profile has been significantly reduced by 400%.

  • 273.
    Azizi, Shoaib
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    A multi-method assessment to support energy efficiency decisions in existing residential and academic buildings2021Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Rapid decarbonization of building stock is essential for the energy transition required to mitigate climate change and limit the global temperature rise below 1.5 °C. The decision-making for the adoption of energy efficiency measures (EEMs) is often complex and involves lasting consequences and risks. The strategy to direct and support the decision makers can significantly increase the adoption rate of EEMs in buildings. This Ph.D. project focuses on facilitating sustainability improvement in buildings by supporting the decision makers who are accountable for the consequences of adopting the EEMs. Energy efficiency improvement is decided and managed differently in various types of buildings and contexts and encounters different challenges and opportunities. Accordingly, it is required to understand the needs to select adequate strategies and to devise effective supporting interventions for energy efficiency improvement.

    The owners of single-family houses are often the occupants who are in charge of the most decisions to improve energy efficiency in their dwellings. The situation is rather different in multi-family buildings and academic buildings in which organizational management adds more complexity and the decisions affect various stakeholders. The studies in this project are based on qualitative and quantitative data collected from single-family houses, multi-family buildings, and university buildings in northern Sweden. Surveys were used to elicit the decision makers' perceptions of different types of buildings. Moreover, sensor data from university buildings were used in the case studies to develop informative metrics for space use efficiency and to analyze the effect of sensor positioning on monitored data.

    The initial work involved understanding the opportunities and challenges of improving energy efficiency in buildings and the tradeoffs between the perceived benefits and barriers. This part of the thesis provided the foundation and inspiration for the rest of the project, including investigating how to bundle several measures and use information and communication technologies (ICT) for building sustainability. The findings show lack of information and evidence that could justify the beneficial outcomes of EEMs is a major barrier for effective decision-making. Clear information on potential improvements allows sharing the responsibilities among different stakeholders and increases the management capacity to handle projects and adopt EEMs. Using feedback tools (for example, space use and/or energy use visualizations) might be an effective strategy to influence decision makers.

    Various studies incorporated in this multidisciplinary Ph.D. thesis develop and investigate strategies to support decision makers to improve energy efficiency in buildings. The findings provide insights to policymakers and businesses to devise intervention strategies for energy efficiency in buildings.

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  • 274.
    Azizi, Shoaib
    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.
    Olofsson, Thomas
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Adoption of Energy Efficiency Measures in Renovation of Single-Family Houses: A Comparative Approach2020In: Energies, E-ISSN 1996-1073, Vol. 13, no 22, article id 6042Article in journal (Refereed)
    Abstract [en]

    Inclusion of energy efficiency measures (EEMs) in the renovation of the single-family housing stock can unlock the potential for much-needed energy efficiency to tackle climate change. Energy renovation (ER) in single-family houses is often promoted as an aggregate process, and EEMs are treated homogenously without sufficient attention to their differences. This study applies a comparative analysis on common EEMs using chi-square test to investigate the influence of factors already found affecting the implementation of ER. This paper addresses the “personal” and “house-related” factors influencing the adoption of EEMs regardless of motives or barriers leading the adopters’ decisions. This strategy is useful to highlight the contexts leading to an increase in the adoption rate of different EEMs. The analysis is based on a questionnaire survey mailed in spring 2017 to 1550 single-family homeowners in the northern region of Sweden. Approximately 60% of respondents showed interest in adopting at least one EEM if they implement a major renovation. About 46% of respondents stated to have at least one indoor environmental problem (IEP) in their houses, and IEPs are found to have significant relations with homeowners’ interest to adopt several different EEMs. The policy implications related to different EEMs are discussed.

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  • 275.
    Azizi, Shoaib
    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.
    Olofsson, Thomas
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Analysing the house-owners’ perceptions on benefits and barriers of energy renovation in Swedish single-family houses2019In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 198, p. 187-196Article in journal (Refereed)
    Abstract [en]

    Single-family houses offer a large potential for energy savings by energy renovation (ER). Homeowners’ motivation to implement ER derives from the benefits and barriers they perceive. Benefits are the positive consequences that can motivate homeowners to act and barriers are the challenges that demotivate them to undertake ER. Different benefits and barriers do not homogenously affect every homeowner. Identifying motivating benefits and demotivating barriers for each specific group among homeowners can shed lights on ER decision-making and enable policies that are more effective. The objective of this study is to contextualize the implementation of ER by understanding how the perceived benefits and barriers influence homeowners. This study links the expected consequences, which are benefits and barriers to the influential factors on ER, which are used to group the homeowners.

    The analysis is based on a questionnaire survey mailed to 1550 owners of single-family houses in northern Sweden. The perceptions of homeowners on benefits and barriers of ER are significantly different between the groups that are motivated and unmotivated to implement ER. Despite the perceived importance of some of the benefits such as energy cost reduction, they may not be determinative for the homeowners’ decision to undertake ER. The homeowners are more likely to implement ER for reasons other than energy use reduction such as for improving the indoor environment. The barriers such as the difficulty of finding a low-interest loan and reliable information sources are found to impede the intention to implement ER among different groups. Policy implications to facilitate ER in single-family houses are discussed.

  • 276.
    Azizi, Shoaib
    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.
    Olofsson, Thomas
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Demand-controlled energy systems in commercial and institutional buildings: a review of methods and potentials2019In: eceee 2019 Summer Study on energy efficiency:: Is efficient sufficient?, European Council for an Energy Efficient Economy (ECEEE), 2019, p. 1444-1450Conference paper (Refereed)
    Abstract [en]

    Heating, ventilation and air-conditioning (HVAC) are by farthe most energy intensive systems in commercial and institutionalbuildings with office spaces. This makes HVAC systemsattractive targets for energy efficiency improvement. New technologicaladvancements can play significant role on improvingenergy efficiency. Such advancements have been also emergedin form of novel management and control strategies, whichmight lead to considerable energy savings with relatively minorinvestments. This paper evaluates demand control HVAC andlighting to assess the energy saving potential of upgrading theconventional building energy systems.

    This paper provides a summary of different methods and occupancydetection technologies. A range of technologies andmethods are covered that vary in complexity, limitations andenergy saving potential. Additional benefits such as demandresponse are evaluated and other emerging applications arediscussed. Based on the review of methods and potentials, thepaper assesses the state of the art in demand controlled energysystems and suggests areas for further research.

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  • 277.
    Azrak, Johan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Ekonomisk optimering av en vätgasanläggning med sektorkoppling till ett fjärrvärmesystem2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Increased human activity and global population have led to an increased energy demand, with most of the energy coming from fossil fuels. Hydrogen is seen as an efficient energy carrier that can be produced using renewable resources and replace fossil fuels. However, hydrogen produced from renewable resources is still expensive compared to production from fossil fuels. There have been few previous studies that have examined the utilization of waste heat from hydrogen facilities and the impact it can have on economic profitability.This study, conducted in collaboration with Research Institutes of Sweden (RISE), aims to optimize a hydrogen production facility, with a predefined hydrogen demand, from an economic perspective and assess whether a sector coupling to a district heating network can improve the economic outcome. In this study, sector coupling means that waste heat is sent from the hydrogen facility to the district heating network. The hydrogen plant consists of an electrolyzer, a fuel cell, and a hydrogen storage. The system is designed to primarily produce a predetermined amount of hydrogen to be used as vehicle fuel. Additionally, the system can be used for electrical energy storage through hydrogen storage if it proves to be economically advantageous. The objectives are to optimize the price at which hydrogen needs to be sold for the facility to break even, sizing the electrolyzer, hydrogen storage, and fuel cell based on optimal operation, and study the factors that affect the optimal operation of the facility.The method used to optimize the hydrogen facility is linear programming in the MATLAB program. The optimization aims to calculate the lowest possible net cost (or highest net income) for the system. All costs and revenues are described linearly, and then all variables that affect costs and revenues are defined. These variables, in turn, depend on conditions as well as linear equalities and inequalities that restrict the values, they can take to influence the result. The optimization is carried out over a period of 1 year with a time step of two hours. Historical electricity prices for 2021 SE3 were used in the study. The variation in electricity prices is difficult to measure, so a simplified electricity price was also created to study the impact of the variation more closely.The results show that the hydrogen should be sold for approximately 36.6 SEK/kg to break even when the price is optimized, and waste heat is not utilized. The utilization of waste heat can reduce the price by 1.6-2.5 SEK/kg depending on whether the waste heat is utilized for parts or the entirety of the year. The electrolyzer and hydrogen storage should be dimensioned based on a predefined hydrogen demand, according to the factors of 4.9 MW/(ton of hydrogen/day) and 1.4 ton/(ton of hydrogen/day), respectively. The heat output that can be utilized from the hydrogen facility can be dimensioned based on a predefined hydrogen demand, according to the factor of 0.9 MW/(ton of hydrogen/day). The results show trends indicating that the electricity price affects the size of the electrolyzer, hydrogen storage, andthe hours during which the electrolyzer is active. Dimensioning the facility as a function of the electricity price has proven to be a complex question, and further studies are needed in that area. One trend indicates that the utilization of waste heat has a smaller impact on the hydrogen price at higher electrolyzer efficiency and a greater impact at lower efficiency. Waste heat that replaces heat from a district heating boiler reduces emissions by approximately 38 kg CO2e/MWh, depending on the existing boilers/fuels of the district heating producer. For investors, the results provide guidelines for the price of hydrogen, estimated dimensioning of the facility, the practical non-profitability of fuel cells, and insights into the economic value of waste heat. For the district heating company, the results mean reduced emissions of carbon dioxide equivalents, an additional heat source, and possibly reduced costs For the Swedish energy system, the results imply that the high variation in electricity prices can be utilized to produce hydrogen, leading to a potential decrease in the price of green hydrogen compared to current levels. Additionally, the utilization of waste heat can contribute to a more efficient energy system.

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  • 278.
    Baas, Leenard
    et al.
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, Faculty of Science & Engineering.
    Mirata, Murat
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, Faculty of Science & Engineering.
    Bio-resource production on the basis of Industrial Ecology in four European harbours, harbour cities and their region2015In: Économie Circulaire et Écosystémes Portuaires (Circular Economy and Port Ecosystems) / [ed] Yann Alix, Nicolas Mat, Juliette Cerceau, Paris: Foundation Sefacil , 2015, 1, p. 223-242Chapter in book (Refereed)
    Abstract [en]

    This chapter re ects the design and starting performance of the Symbiotic bio- Energy Port Integration with Cities by 2020 project (EPIC 2020). The EPIC 2020 project is coordinated by the city of Malmö and is performed in four harbour cities: Malmö in Sweden, Mantova in Italy, Navipe-Akarport in Greece, and Wismar (including Rostock) in Germany. A number of expert organisations and energy companies also take part in the project.

    The overall objectives of EPIC 2020 are to build operational and strategic capacity and know-how to promote ef cient use of available bioenergy resources, ef cient conversion technologies and interactions between different biomass supply chains. EPIC 2020 targets the untapped bioenergy resource potential of ports and port regions and the challenge of generating urban economic growth based on bioenergy resources. The project applies the industrial symbiosis approach to achieve its overall objectives.

    Ports provide crossing points between transport modes of goods and resources, with connections to hinterland and on-site industrial activities and a nearby urban setting. This means that ports, despite their limited areal footprint, have access to signi cant quantities of bio wastes, surrounding bioenergy resources, biomass from crossing supply chains and energy from intensive activities. The aim is to create platforms for the transformation of port areas to ef cient and carbon-neutral urban-integrated energy systems, where residual bio and energy resources and linear biomass supply chains are utilized as local and network resources.

    The EPIC 2020 project is halfway the 3-year performance framework. Re ection to primary results is provided. 

  • 279.
    Babashova, Nazrin
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Detection of NORM contamination in LNG systems2020Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Naturally occurring radioactive material (NORM), which is present in the oil and gas industry, can pose a risk to the workers engaged in the activities in this field. Nevertheless, to our knowledge, there is no study on NORM presence and NORM measurement in liquefied natural gas (LNG) fuel systems and installations. Therefore, the question on whether NORM, particularly radon and radon progeny, can pose a risk to the health of employees, is still open. This study provides the initial base for further investigation and real NORM measurement. In this study, all stages of radon and radon decay products movement and deposition starting from natural gas production till the final destination are analyzed and reviewed. Several techniques for NORM detection and measurement are proposed. In the case if radon levels exceed the reference level, several actions towards radon reduction are proposed.

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  • 280.
    Babu, Aishwarya
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Effect of various rate promoters on the absorption rate of carbon dioxide in potassium carbonate solvents2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The ever-growing need to reduce CO2 emissions has led to an increased emphasis on carbon capture technologies. MEA (monoethanolamine) is considered the benchmark solvent for CO2 capture due to its high rate of absorption. However, MEA is prone to degradation, forms toxic side products and its regeneration has a high energy demand. Another solvent with similar technological maturity is aqueous potassium carbonate (K2CO3) that is used in the so-called hot-potash carbonate (HPC) process. However, the rate of absorption in aqueous K2CO3 is low in comparison to MEA calling for the addition of rate promoters to enhance the absorption rate. 

    This thesis investigates the effect of different rate promoters on the absorption rate of potassium carbonate. For this, absorption experiments on the laboratory scale were conducted in a stainless-steel autoclave reactor under controlled conditions. Various promoters have been explored, namely the organic promoters glycine, piperazine, and MEA, and the inorganic promoters boric acid and vanadium pentoxide. The promoter concentration was varied between 3 wt% to 7 wt% while keeping the concentration of K2CO3 constant at 25 wt%. The operating conditions, such as the initial partial pressure of CO2 and the temperature were 5 bar and 50°C, respectively. The inorganic promoters were studied alone as well as in blends with K2CO3 to understand the effect of each promoter.

    The organic promoters demonstrated a significant enhancement of the absorption rate compared to unpromoted K2CO3. Regarding the inorganic promoters, vanadium pentoxide showed comparable results to organic promoters with only 3 wt%. When looking at the results of vanadium and boric acid, increasing concentration of boric acid resulted in a decrease in the absorption rate. The experimentally measured absorption rate are fitted to a simple absorption model from which an apparent absorption rate for the promoted solvents was derived. 

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  • 281.
    Back, Nina
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Optimering av underhållsstrategier i åldrande kärnkraftsanläggningar: En litteratur- och intervjustudie med kompletterade fallstudie kring kabel- och rörgenomföringar2020Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This report is based on a literature study and interviews regarding maintenance strategies and component replacements in nuclear power plants. Focuses of the study are on components which tend to more commonly be affected by degrading aging mechanisms. Exemplification is done with a complementary case study about cable- and pipe transits with packing pieces made of polymeric materials. A frequently used application for cable- and pipe transits in Swedish NPPs is manufactured by MCT Brattberg AB. 

    Result obtained from interviews with relevant personnel’s and the literature study providing knowledge about prevailing safety regulations at Swedish nuclear facilities. Moreover, information is gained about how aging affects the features of materials over time and that it is the basis for determining the qualified lifetime of systems and components. Further on this could be of specific interest considering that the majority of the worlds NPPs are close to its intended lifetime and soon entering a phase of LTO. A proper aging management is an important factor when it comes to a safe and reliable operation of an NPP. 

    The case study compares two different maintenance strategies which are supported by the obtained result from interviews and the literature study. Considering ecological and economic impacts of the strategies, the one with the greatest potential to reduce negative influences are exemplified. Chosen method included practical hardness measurement with a portable durometer at packing pieces for cable- and pipe transits. Measured hardness of the packing pieces indicates at what degree which they have been affected by degrading aging mechanisms given different circumstances.  

    The obtained result from the two different parts of the report is corresponding to each other. Packing pieces consisting polymers hardens as they age. Elevated temperatures and higher dose rates accelerates the aging process. Represented method of the case study is practically viable at existing NPPs at Forsmark. Presented strategy should be able to assist with an ecological and economic optimization maintenance work for cable- and pipe transits.

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    Examensarbete2020NinaB
  • 282.
    Backlund, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Modellering, simulering och analys av kärnreaktorn BWRX-3002023Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The demand for fossil-free energy production is rising due to electrification and increased consumption in the energy system. There are also multiple climate goals to reach, to preserve the possibilities of a sustainable future.

    A response to this is the BWRX-300, a natural circulation boiling water small modular reactor (SMR) concept developed by GE Hitachi Nuclear Energy. It is currently at the forefront of study for many power utility companies around the world. For decision making it is of interest to investigate the capabilities of new facilities. This Master Thesis work's aim is to study the BWRX-300 reactor's feasibility together with evaluating and optimizing its performance using the core simulation softwares Casmo5 and Simulate5.

    This is carried out by first verifying Simulate5's natural circulation capabilities by modifying an existing forced-circulation reactor to natural circulation, then comparing simulation results to real world data. 

    Next a comprehensive model of the BWRX-300 reactor pressure vessel is modelled and validated. Equilibrium cores for 12- and 24-month cycle lengths are then simulated where key reactor performance metrics such as fuel economy, safety margins, axial profiles (of voids and pressure drop) and reactor characteristics are extracted. The effect of different fuel assembly designs in the BWRX-300 reactor core is investigated to find first core design optimums. Furthermore the decay heat removal system in the BWRX-300 is investigated. Lastly the results are used to evaluate the optimal operating mode given the current and future more dynamic projected state of the energy system. 

    The results show that there are no real technical difficulties while operating the BWRX-300 reactor for 12 or 24 months. The decay heat removal system and core flow characteristics provide abundant coolant flow to maintain long term fuel integrity during both normal and abnormal operation modes. More or less routine core design optimization work is required to obtain sufficient safety margins and improve fuel economy. It is observed that the smaller reactor core requires an increase in average fuel enrichment to maintain criticality throughout the cycle, potentially creating an incentive to raise the current licensing limit. However it is deemed possible to avoid this by conducting further fuel design optimization work.

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  • 283.
    Backlund, Sandra
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Efficient improvement of energy efficiency in small and medium- sized Swedish firms2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This is a dissertation about efficient implementation of energy efficiency measures in small and medium-sized Swedish firms. The aim is to investigate the potential for economically efficient implementation of energy efficiency improvement measures in small and medium-sized firms. The thesis contains five papers that analyse different aspects that have been put forth in policy documents and academic debate as  methods to improve energy efficiency in non-energy intensive sectors.

    By reading policy documents, interviewing representatives of small and medium- sized firms and energy auditors as well as analysing data from the Swedish energy audit program, different aspects of energy management practices, energy services and energy audits are considered. The thesis is the product of an interdisciplinary context but economic theory is at the foundation of the analysis and has helped formulate questions and hypotheses that have been tested and explored with the data.

    The results show that while the potential for improving energy efficiency in the small and medium- sized sector in Sweden is large there are challenges to realizing it in each individual firm. There is potential for improving energy efficiency in the sector and not just for investments in new technology but also for adjusting existing machinery and changing behaviour, but costs for investigating the potential and implementing the measures are large relative to the improvement potential in each company. Energy management practices in this sector are lacking and energy services will only be demanded if reduction in production cost is estimated larger than transaction costs of the service. The Swedish energy audit program has led to the implementation of energy efficiency improvements in the participating firms but compared to other policy instruments it has been a less cost-efficient way to improve energy efficiency in Sweden.

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  • 284.
    Backlund, Sandra
    et al.
    Swedish environmental protection agency.
    Eidenskog, Maria
    Linköping University, Faculty of Arts and Sciences. Linköping University, Department of Thematic Studies, Technology and Social Change.
    Energy service collaborations: it is a question of trust2015In: Socio-technical perspectives on sustainable energy systems / [ed] Jonas Anshelm, Kajsa Ellegård, Jenny Palm, Harald Rohracher, Linköping: Linköping University , 2015, p. 149-167Chapter in book (Other academic)
  • 285.
    Backlund, Sandra
    et al.
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Eidenskog, Maria
    Linköping University, The Tema Institute, Technology and Social Change. Linköping University, Faculty of Arts and Sciences.
    Energy services in Swedish industrial firms: A multidisciplinary analysis of an emerging market2011Report (Other academic)
    Abstract [en]

    The European commission highlight the energy service market as an important means to improve energy efficiency. Both the Energy service directive and the new suggested Energy Efficiency Directive urge member states to facilitate market development for energy services. The industrial sector is estimated to have large energy efficiency potential. The aim of this multidisciplinary report is to investigate the state of the Swedish energy service market 2011, both from the supply side and from the industrial demand side in order to contribute with knowledge to the discussion of energy services as a way to improve industrial energy efficiency. Economic market theory and Socio-technical theory (the theory of economization presented by Caliskan and Callon) is used to analyse different aspects of the emerging market. The results show that the market for industrial energy services in Sweden is more extensive than previous reports have assessed. Our study describes how energy service collaborations can be complex and how calculations and measurements of expected energy savings lead to controversies and power imbalances.

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  • 286.
    Backlund, Sandra
    et al.
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Thollander, Patrik
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Estimations of energy efficiency management potential in small and medium sized firms2014Manuscript (preprint) (Other academic)
    Abstract [en]

    Energy management; information and knowledge gained by continuous work and attention to energy use can help discover inefficiencies, malfunctioning equipment and assess the performance and operation. This paper investigates how small and medium sized firms and energy auditors estimate energy efficiency potentials from energy management measures by studying the firms that have participated in the Swedish energy audit program. The largest potential for energy efficiency improvements in the energy audit reports is found in generic technologies and support processes, i.e. cross cutting technologies mainly in ventilation, space heating and lighting. Out of the suggested measures investments in new technology accounts for 48% of the estimated potential, and adjustments of existing technology for 27%. Behavioural changes in the energy audit reports accounts for a vanishingly small percentage of total suggested energy efficiency measures in the energy audit reports. Firms participating in the study estimate a higher potential for energy efficiency from behavioural changes than the energy auditors, as high as a quarter of the total potential. Implementation rates of suggested measures from the energy audit program rates are higher in the behavioural category. Despite this, the study shows that energy management practices at the firms are lacking. Energy auditors argue that energy management has low priority in firms because firm’s main focus on core business.

  • 287.
    Backlund, Sandra
    et al.
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Thollander, Patrik
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Impact after three years of the Swedish energy audit program2015In: Energy, ISSN 0360-5442, Vol. 82, p. 54-60Article in journal (Refereed)
    Abstract [en]

    The Swedish energy audit program is a publicly financed program, mainly targeting small and medium-sized firms to help them finance energy audits. By examining suggested and implemented energy efficiency measures from the energy audits conducted in 241 firms in the program, the aim of this paper is to examine the energy efficiency implementation gap and the cost efficiency of the program.

    The autis show that the firms’ average annual energy efficiency improvement potential is between 860 and 1270 MWh/year which corresponds to a total energy efficiency improvement potential of between 6,980 -11,130 MWh / firm. The implementation rate of the suggested energy efficiency improvement measures in the SEAP is 53%. The program has resulted in investments in energy efficiency improvements between € 74,100- € 113,000 / firm.

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  • 288.
    Backlund, Sandra
    et al.
    Naturvårdsverket, Sweden.
    Thollander, Patrik
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Paramonova, Svetlana
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Rohdin, Patrik
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Karlsson, Magnus
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    A regional method for increased resource-efficiency in industrial energy systems2014In: eceee Industrial Summer Study Proceedings, 2014Conference paper (Refereed)
    Abstract [en]

    The impact of global climate change as a result of greenhouse gas emissions (GHG), primarily from the use of fossil fuels, is demanding actions from all sectors of society. The industry sector is one of the world’s largest energy using sectors and GHG emitters. Improved energy efficiency in industry is one of the foremost means of improving energy efficiency and reducing GHG emissions. Research shows that despite large untapped potentials for improved energy efficiency in industry, cost-efficient energy efficiency measures are not always implemented, explained by the existence of barriers to energy efficiency, e.g. information imperfections and asymmetries. Moreover, research shows that a major energy efficiency potential lies in the energy system and the way it is governed. For regional governments, the industrial energy use is difficult to affect as they only have indirect power to influence the decisions in those organizations. This underlies the importance of developing methods on how a region can support and effectively contribute to energy efficiency improvements in the local industry. So far, methods are limited related to regional governance of industrial energy systems. The aim of this paper is to present a structured methodology for improved regional resource efficiency in the local industry from a regional perspective, inspired by the Triple Helix Model. Results display the county administrative board of administration’s current method how to target industry, and ends with a proposal for how the methods could be improved.

  • 289.
    Backman, Filippa
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Civil and Industrial Engineering.
    Stafberg, Amanda
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Civil and Industrial Engineering.
    Sterner, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Civil and Industrial Engineering.
    Wesslén, Alva
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Civil and Industrial Engineering.
    Paving the Path to Self-Sufficiency: Optimizing Photovoltaic Installations on Facilities with Emphasis on Consumption Patterns and Economic Viability2023Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This bachelor's thesis explores the potential of Skolfastigheter's facilities to achieve self-sufficiency through solar power while maintaining economic feasibility. The study specifically examines the economic feasibility of various solar power installation sizes, while also exploring key characteristics of school facilities that influence their level of self-sufficiency. To assess this, the report is structured into several steps. The initial step involves identifying properties with the potential to achieve Skolfastigheter's objective of being 15 % self-sufficient and subsequently ranking them. The following step involves evaluating the maximum potential self-sufficiency of a few selected properties through an optimization problem, with an upper limitation in investment cost and maximal capacity. Once optimal self-sufficiency is detected and evaluated a sensitivity analysis is conducted to test the model's robustness by considering different electricity prices and orientations. The results indicate that fluctuating electricity prices have a significant effect on the potential size of the solar panel system, while the orientation has a minor effect when optimizing for self-sufficiency. The key characteristic for achieving optimum self-sufficiency is an even consumption pattern throughout the year, and the facility size is mainly dependent on the current electricity pricing. Furthermore, it is highly probable that the current 15% self-sufficiency threshold for Skolfastigheter AB can be surpassed.

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  • 290.
    Backman, Fredrik
    Linköping University, Department of Thematic Studies, Technology and Social Change. Linköping University, Faculty of Arts and Sciences.
    Barriers to Energy Efficiency in Swedish Non-Energy-Intensive Micro- and Small-Sized Enterprises-A Case Study of a Local Energy Program2017In: Energies, E-ISSN 1996-1073, Vol. 10, no 1, article id 100Article in journal (Refereed)
    Abstract [en]

    Improved energy efficiency has become a strategic issue and represents a priority for European competitiveness. Countries adopt various energy policies on local and national levels where energy audit programs are the most common energy end-use efficiency policy for industrial small-and medium-sized enterprises (SMEs). However, studies indicate that cost-efficient energy conservation measures are not always implemented, which can be explained by the existence of barriers to energy efficiency. This paper investigates how Swedish municipalities can support local micro-and small-sized enterprises with improved energy efficiency and the existence of different barriers to the implementation of energy efficiency. Relating this empirical case study to the theoretical barriers outlined in the text, this study found that the major explanatory factors related to non-implementation of cost-effective energy efficiency measures among micro-and small-sized industrial enterprises were bounded rationality (lack of time and/or other priorities), split incentives (having other priorities for capital investments), and imperfect information (slim organization and lack of technical skill). This study also found that information in the form of a report was the main thing that companies gained from working on the project "Energy-Driven Business". Notably, the study involved companies that had participated in a local energy program and, still, companies face major barriers inhibiting implementation, indicating a need to further study other alternative policy models and how knowledge transfer can be improved.

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  • 291.
    Backéus, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Electricity.
    Ombyggnad av Klockarforsen2021Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The water level at Hjälta power station in Faxälven varies depending on the water flow that passes through the power station. The varying water level causes head losses, lesser energy generation and loss of income. The varying water level is caused by a short but narrow and shallow part of the river, known as Klockarforsen. To increase the water flow and decrease the resulting head losses, it is possible to dredge the stream bed in Klockarforsen in order to achieve a greater depth. 

    By using a sonar to map the bathymetry in Klockarforsen, it has been possible to create a model of this part of the river. The model has been constructed and processed in ArcGIS and HEC-RAS, in order to examine how a dredging would affect the water level, head losses, energy generation, income and retention water levels. 

    The results show that a dredging to a depth of four or six meters could raise the water level and the head height at Hjälta power station with an average of 0.32 and 0.41 meters, respectively. During the period between 2014-2019, 1.11-3.84 GWh more energy would have been generated annually if Klockarforsen had been dredged. Which means that the income for the power station would have increased by between MSEK 0.39-1.3 per year. The increased energy generation and income are considerable, but in terms of how much energy and income is generated annually, the figures are more modest. The energy production and income increase by between 0.13-0.3 percent annually. 

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  • 292.
    Baena Juan, Cristian
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Comparison of the performance of silicon and thin film solar cells at the laboratory of the University of Gävle2016Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The huge environmental awareness emerging last years by reason of global warming and greenhouse effect, on one hand, and the need of finding other sources of energy production and conversion due to the declining of fossil resources and the increasing cost of this kind of energy resource, on the other hand, both have led position renewable energies as a powerful alternative on the energy production and conversion.

    PV-systems have emerged at an exponential rate in recent year as the main candidate and a satisfactory possibility with respect to environmental and economic sustainability.

    Nowadays, the large volume on photovoltaic market is currently dominated by four types of solar cells, divided by the semiconductor material used to absorb light and convert the energy into electricity: (1) crystalline silicon (monocrystalline and polycrystalline), (2) amorphous silicon, (3) CIGS and (4) cadmium telluride; and among them, monocrystalline silicon and CIGS technologies are installed on the building 45 of the University of Gävle, at the south face of the laboratory.

    In this context and with the motivation to contribute knowledge on PV field, a comparison between single crystal solar technology and thin film CIGS technology has carried out through f ratio and performance ratio procedures in order to perform an assessment of the energy conversion of each one under field conditions.

    A logger monitors the power conversion from the PV modules since June 2014 while two pyranometers monitor global and diffuse solar radiation since March 2016. It must take into account that only clear sunny days have been considered during a period from 8:00 to 14:00 in order to avoid shadows effect on the PV systems.

    The results come to conclude that single crystal silicon modules present a better behavior with respect to energy conversion under no shadows effect conditions by two reason: (1) f ratio, relationship of PV conversion per kW (PV yield) between CIGS and single crystal silicon, is about 87.25% with some variations along a day due to ambient temperature, cell temperature and incidence angle; (2) PV module's performance ratio of monocrystalline silicon modules is higher than thin film CIGS ones during a sunny day about 87.56% and 76.38%, respectively; and they are consistent with usual performance ratio values between 80% and 90% since 2010 onwards.

    In light of the outcome and in order to confirm these conclusions, it intends to launch a project with the objective of evaluating the data collected and compare the performance of the module after a year of measurements outdoors by the PV module's performance ratio procedure.

    Along the same lines, the next step of the University of Gävle will be to launch a project with the objective of evaluating the potential to be self-sufficient.

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  • 293.
    Bagheri, Marzieh
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Integrated sewage sludge treatment scenarios – techno-economic analysis on energy and phosphorus recovery2022Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Sewage sludge is a by-product of wastewater treatment that simultaneously gathers contaminants, valuable organic matter, and nutrients. The treatment of the increasing amount of sewage sludge is important from both pollution prevention and resource recovery perspectives as i) large shares of mineral phosphorus, listed as a critical raw material, terminate in the sewage sludge, and ii) energy recovery from sewage sludge can cover the energy-intensive demand of the treatment process. Previous research has identified sewage sludge combustion as a suitable treatment approach as it both addresses contaminant destruction and paves the way for efficient phosphorus recovery from the sewage sludge ash. The commercial development of this practice has, however, been slow. Therefore, this thesis aims to investigate the challenges in sustainable sewage sludge management, and to, in more detail, identify the economic viability of energy and phosphorus recovery from sewage sludge through combustion.

    The thesis’ aim is divided into two objectives addressed in three papers. First, to investigate how different aspects of sewage sludge management, such as contaminants, economic efficiency, technical aspects, and legislation, evolve and interact. This has been done by a review of sewage sludge management research over fifty years (Paper I). Second, to investigate the economic viability of simultaneous energy and phosphorus recovery from sewage sludge by comparing different technology and market scenarios. This has been done for i) new sewage sludge mono-/co-combustion plants (Paper II), and ii) the integration of treatment technologies, mainly anaerobic digestion, hydrothermal carbonization, and combustion, in an existing wastewater treatment plant (Paper III). 

    Results from the analysis of sewage sludge management research (Paper I) show a narrow-focused perspective that often excludes inseparable aspects such as combination of economic consideration and advanced extraction technology. The investment viability of a new mono-/co-combustion of sewage sludge (Paper II) is highly conditional on heat, electricity, and fertilizer price, and external financial support is often a crucial requirement. Sewage sludge co-combustion with potassium-rich biomasses improves sewage sludge quality and forms usable ash as fertilizer without further need for phosphorus recovery technology. In this case, the economic feasibility of the process is independent of usable ash revenue, which stimulates a competitive selling price for the ash, thereby improving the marketing of sludge-based fertilizer. Avoided disposal costs of sewage sludge for a retrofitted wastewater treatment plant by introducing hydrothermal carbonization (Paper III) shows good economic feasibility while recovering phosphorus. Integrating anaerobic digestion, hydrothermal carbonization, and combustion may also improve investment incentives by improving energy outputs and phosphorus recovery. The economic feasibility is contingent on product (hydrochar, heat, electricity) prices and sensitive to added equipment costs, and costs for sludge transportation and disposal. 

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  • 294.
    Bagheri, Marzieh
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Sewage Sludge Treatment Scenarios: Techno-Economic Analyses of Energy and Phosphorus Recovery Focusing on Implementation Challenges2024Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Managing sewage sludge, an inevitable by-product of wastewater treatment processes rich in both contaminants and valuable resources, presents a dual challenge: ensuring pollution prevention by immobilizing or destroying contaminants, and facilitating resource recovery. Balancing these objectives is critical given the growing volumes of sewage sludge and the imperative to both protect the environment and recover valuable resources. The unknown risks of land application of sludge, the currently most common disposal method, make thermal conversion a promising alternative, as it enables energy recovery, the breakdown of potentially harmful organic compounds, and the formation of volume-reduced, sanitized products. Despite the technical feasibility, the commercial development of advanced recovery technologies has been slow. 

    This thesis aims to expand knowledge on different sewage sludge treatment and disposal scenarios under varying conditions; thereby shedding light on implementation challenges, local opportunities, and the financial dynamics critical for phosphorus and energy recovery from the perspectives of wastewater treatment plants, investors, and policymakers. The aim is primarily addressed by performing techno-economic analysis of sewage sludge treatment scenarios, covering the entire sludge treatment process from sludge treatment to end products and disposal (Paper II-V). The techno-economic analysis is supplemented by a review of academic research on sewage sludge management from 1971 to 2019 (Paper I). 

    Results from the analysis of sewage sludge management research (Paper I) show a narrow-focused perspective that often misses the broader, interconnected aspects of sewage sludge management, leading to research that, while detailed, fails to capture the complexity of the field. The investment viability of a new mono-/co-combustion plant for sewage sludge (Paper II) is highly conditional on heat, electricity, and fertilizer prices, and external financial support is often a crucial requirement. Cocombustion of sludge (in low ratios) with K-rich agricultural biomass requirement in and energy demand of a thermal dryer, and by yielding ash that contains phosphorus in a plant-available form. Utilizing existing heat facility (Paper III) and co-combustion to mitigate investment costs and energy demand in sludge management showed the potential to offer a cost-effective alternative to land application. However, the viability of co-combustion hinges on both a high heat market price (Paper II) and the proximity of affordable biomass resources (Paper III). Without these conditions, co-combustion may increase the financial burden of sludge management on wastewater treatment plants and policymakers. 

    Retrofitting a wastewater treatment plant by integrating hydrothermal carbonization in sludge treatment (Paper IV), demonstrated good economic feasibility, primarily due to the avoided disposal costs, while also recovering phosphorus. However, integrating hydrothermal carbonization in a system designed for a thermal dryer may cause a significant reduction in electricity production.

    Given the high moisture content of sludge and the low market prices for fertilizer, the potential revenue from energy and phosphorus recovery is inadequate to solely drive investment in advanced sewage sludge treatment technologies (Papers II-V). This issue is exacerbated by the fact that most wastewater treatment plants are small in scale. Collaborative sludge management across neighboring wastewater treatment plants (Paper V) increases phosphorus recovery capacity and leverages economies of scale, fostering investment in advanced technology. This strategy presents a significant opportunity to lower the treatment costs and offers a competitive alternative to land application, while encompassing energy and phosphorus recovery into the sludge treatment.

    In conclusion, resource recovery and pollution prevention in sludge management is a complex task that necessitates simultaneous consideration of technical aspects, product quality, site-specific conditions, and profitability to ensure a comprehensive and viable approach. Leveraging local infrastructure and resources in sewage sludge management is crucial, highlighting the ecessity for strategies to be tailored to the local opportunities and limitations. Such an approach outperforms mono-combustion by eliminating the investment ensures that solutions are not only environmentally sustainable but also economically viable and socially acceptable. 

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  • 295.
    Bagheri, Marzieh
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Bauer, Torben
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Ekman Burgman, Linus
    Department of Thematic Studies, Technology and Social Change at Linköping University, 58183, Linköping, Sweden.
    Wetterlund, Elisabeth
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Fifty years of sewage sludge management research: Mapping researchers' motivations and concerns2023In: Journal of Environmental Management, ISSN 0301-4797, E-ISSN 1095-8630, Vol. 325, article id 116412Article in journal (Refereed)
    Abstract [en]

    Sewage sludge management is torn between a desire for pollution prevention and reuse of a valuable resource. Reconciling these interests in sustainable management is a challenge for researchers. This study focuses on how research on sewage sludge management practices has evolved and scrutinizes how this research is interlinked with concerns and societal issues such as contaminants, economic efficiency, and legislation. Based on published academic papers on sewage sludge management between 1971 and 2019, this study found four trends in research focused on sewage sludge management: a decreasing interest in disposal (landfilling and sea dumping), a dominant interest in land application, a growing interest in sewage sludge as product, and a stable interest in energy recovery. Research on disposal focuses on increasing sludge volumes, legislative changes, and economic challenges with an interest in waste co-treatment. Research on land application concerns nutrient use and contaminants, mainly heavy metals. Research on sewage sludge as a product focuses on the extraction of certain resources and less on use of sewage sludge specifically. Research on energy recovery of sewage sludge focuses on volume reduction rather than contaminants. Two-thirds of the papers are detailed studies aiming to improve single technologies and assessing single risks or benefits. As management of sewage sludge is multifaceted, the narrow focus resulting from detailed studies promotes some concerns while excluding others. Therefore, this study highlights potential gaps such as the combination of nutrient use and disposal and energy recovery and nutrient use. 

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  • 296.
    Bagheri, Marzieh
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Wetterlund, Elisabeth
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Introducing hydrothermal carbonization to sewage sludge treatment systems—a way of improving energy recovery and economic performance?2023In: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 170, p. 131-143Article in journal (Refereed)
    Abstract [en]

    Hydrothermal carbonization (HTC) can mitigate the disposal costs of sewage sludge in a wastewater treatment plant. This study analyzes the impact of integrating HTC with anaerobic digestion (AD) and combustion from a combined energy and economic performance perspective. Net energy balance and investment opportunity are investigated for a number of technical scenarios considering i) different combinations of the technologies: AD + HTC, AD + thermal dryer + combustion, and AD + HTC + combustion, ii) different options for HTC process water treatment: wet oxidation (WO) + AD, and direct return to AD, and iii) different products: heat-only, heat and electricity, hydrochar, and phosphorus.

    The results show trade-offs between investment cost, self-supplement of heat, and output electricity when WO is used. In AD + HTC, net heat output decreases compared to the reference plant, but avoided disposal costs and hydrochar revenue result in profitable investment when the process water is directly returned to the AD. Although HTC has a lower heat demand than the thermal dryer, replacing the thermal dryer with HTC is only possible when AD, HTC, and combustion are connected, or when WO covers HTC’s heat demand. HTC may impair the electricity production because of the necessity for a high-temperature heat source, whereas the thermal dryer can utilize a low-temperature heat source. In conclusion, energy advantages of HTC in AD + HTC + combustion are insufficient to provide a promising investment opportunity due to high investment costs of HTC. The investment opportunity improves by co-combustion of hydrochar and external sludge.

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  • 297.
    Bagheri, Marzieh
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Öhman, Marcus
    Wetterlund, Elisabeth
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Economic viability of co-combusting sewage sludge with agricultural biomasses: a resource-efficient strategy for sludge treatment and phosphorus recovery in SwedenManuscript (preprint) (Other academic)
  • 298.
    Bagheri, Marzieh
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Öhman, Marcus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Wetterlund, Elisabeth
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Techno-Economic Analysis of Scenarios on Energy and Phosphorus Recovery from Mono- and Co-Combustion of Municipal Sewage Sludge2022In: Sustainability, E-ISSN 2071-1050, Vol. 14, no 5, article id 2603Article in journal (Refereed)
    Abstract [en]

    This study evaluates the techno-economic feasibility of energy and phosphorus (P) fertilizer (PF) recovery from municipal sewage sludge (MSS) through incineration in new combustion plants. We evaluated the economic impact of five critical process design choices: (1) boiler type, (2) fuel (MSS mono-combustion/co-combustion with wheat straw), (3) production scale (10/100 MW), (4) products (heat, electricity, PF), and (5) ash destination. Aspen Plus modeling provided mass and energy balances of each technology scenario. The economic feasibility was evaluated by calculating the minimum selling price of the products, as well as the MSS gate fees required to reach profitability. The dependency on key boundary conditions (operating time, market prices, policy support) was also evaluated. The results showed a significant dependency on both energy and fertilizer market prices and on financial support in the form of an MSS gate fee. Heat was preferred over combined heat and power (CHP), which was feasible only on the largest scale (100 MW) at maximum annual operating time (8000 h/y). Co-combustion showed lower heat recovery cost (19–30 €/MWh) than mono-combustion (29–66 €/MWh) due to 25–35% lower energy demand and 17–25% higher fuel heating value. Co-combustion also showed promising performance for P recovery, as PF could be recovered without ash post-treatment and sold at a competitive price, and co-combustion could be applicable also in smaller cities. When implementing ash post-treatment, the final cost of ash-based PF was more than four times the price of commercial PF. In conclusion, investment in a new combustion plant for MSS treatment appears conditional to gate fees unless the boundary conditions would change significantly.

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  • 299.
    Bahena, Rodrigo
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Energy recovery through anaerobic co-digestion of food waste and wastewater treatment sludge: A proposition of a water treatment and biogas plant for a floating island in Stockholm.2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The urge for more sustainable living motivated the Stockholm Tiny House Expo. The project aims to build a floating, sustainable, man-made island for living and working outside of Stockholm. This paper proposes a waste management method with possible energy recovery for the island. It introduces a comprehensive system that integrates decentralized wastewater treatment with energy generation through anaerobic treatment. A by-product of the wastewater treatment process, the sludge, is combined with food waste to generate energy through biogas. The island’s organic waste (wastewater and food waste) is thereby managed sustainably. The results of this report require further research. The energy supply from the biogas reactor was calculated to be 52.19 MWh. The wastewater treatment process was designed with an objective of 90% reduction of BOD5, to comply with the Swedish regulations for wastewater discharge to natural bodies of water, including the ocean. The system's total volume proposed is 11.25 m3, which is the sum of the volumes of all the reactors, or tanks, needed to complete the treatment. 

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  • 300.
    Bahilo Rodríguez, Edgar
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Power Plant Operation Optimisation: Unit commitment of gas turbines using Machine Learning and MILP programming2018Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
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