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- Bastholm, Caroline, 1981-
(författare)
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Micro-grids supplied by renewable energy : Improving technical and social feasibility
- 2019
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Universal access to electricity stands high on the global agenda and is regarded as essential for positive development in sectors such as health care, education, poverty reduction, food production and climate change. Decentralized, off-grid electrification is deemed an important complement to centralized grid extension. By utilizing a renewable energy source, solar technology for the generation of electricity, photovoltaics (PV) is being considered as a way forward to minimize the environmental problems related to energy use.This thesis aims to contribute to improving the technical and social feasibility of PV and PV-diesel hybrid micro-grids for the purpose of providing access to electricity to people in rural areas of countries with low level access to electricity. In line with these general aims, the focus has been to address three questions related to challenges in three phases of rural electrification. The work has a multi-disciplinary approach, addressing mainly technical and social aspects of long-term sustainability of micro-grids, in a local context, and the changes these are intended to generate. One specific micro-grid in Tanzania has been used as a major case study.The thesis is developed through three papers, all presenting methodologies or aspects for investigation in rural electrification projects and studies in general, and for PV-diesel hybrid micro-grids in particular. Paper I puts forward a methodology to facilitate non-social scientific researchers to take social aspects increasingly into consideration. Paper II is a guideline to support system users to increasingly apply an evaluation based system operation. Paper III specifically highlights the importance to consider blackouts when investigating how an existing off-grid PV-diesel hybrid system shall be utilized when a national grid becomes available.
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| 2. |
- Gradén, Mattias, 1974-
(författare)
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Vindkraft i Dalarna : Från acceptans och lokalisering till planering och eftertanke
- 2011
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis examines prerequisites for wind power diffusion in a county in Sweden that quite recently was concidered to be of interest for electricty production from renewable energy sources. Three different municipalities: Falun, Mora and Orsa in the county of Dalarna are highlighted. Their view on permitting processes of wind power installations are investigated. Other actors, such as exploiters and local citizens are also being analysed. This study shows that the local acceptance was very high when the first wind power parks were built, much thanks to local politicians and local citizens. For the politicians the wind power symbolised a key to a better green society, for the local citizens the wind power meant some economical advantages. The first wind power parks were localised to areas because of good wind conditions and social factors, especially from local communities. However, results from this study shows that the acceptance for wind power the last few years, in generel, has decreased. The local authorities have also been conscious of some negative consequenses from already built wind power parks. As a response they started to add planning tools to the permitting process.
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| 4. |
- Nilsson, Maria, 1984-
(författare)
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Tribology in Metal Working
- 2012
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis focuses on the tribological performance of tool surfaces in two steel working operations, namely wire drawing and hot rolling. In all forming operations dimensions and surface finish of the products are of utmost importance. Forming basically includes three parts – forming conditions excluded – that may be changed; work material, tool and (possibly) lubricant. In the interface between work material and tool, the conditions are very aggressive with – generally or locally – high temperatures and pressures. The surfaces will be worn in various ways and this will change the conditions in the process. Consequently, the surface finish as well as the dimensions of the formed product may change and in the end, the product will not fulfil the requirements of the customer. Therefore, research and development in regard to wear, and consequently tribology, of the forming tools is of great interest.The investigations of wire drawing dies focus on coating adhesion/cohesion, surface characteristics and material transfer onto the coated steel both in laboratory scale as well as in the wire drawing process. Results show that it in wire drawing is possible to enhance the tribological performance of drawing dies by using a lubricant together with a steel substrate coated by a polished, dual-layer coating containing both hard and friction-lowering layers.The investigations of hot rolling work rolls focus on microstructure and hardness as well as cracking- and surface characteristics in both laboratory scale and in the hot strip mill. Results show that an ideal hot work roll material should be made up of a matrix with high hardness and a large amount of complex, hard carbides evenly distributed in the microstructure. The surface failure mechanisms of work rolls are very complex involving plastic deformation, abrasive wear, adhesive wear, mechanical and thermal induced cracking, material transfer and oxidation.This knowledge may be used to develop new tools with higher wear resistance giving better performance, lower costs and lower environmental impact.
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| 5. |
- Psimopoulos, Emmanouil
(författare)
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Smart control of PV and exhaust air heat pump systems in single-family buildings
- 2019
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Recently, decentralized household photovoltaic (PV) systems have become more affordable and there is a tendency to decrease subsidies for the PV excess electricity fed into the grid. Therefore, there is growing interest in methods to increase the self-consumption (SC), which is the part of the electricity produced by PV and directly consumed on buildings. It has been found that battery storage is an effective way to achieve this. When there is a heat pump system installed, thermal energy storage using the thermal mass of the building or hot water tanks, can also be used to increase the household self-sufficiency and minimize the final energy use. The main aim of this thesis is to develop operational control strategies for the heating system of a single-family house with an exhaust air heat pump, a photovoltaic system and energy storage. In order to accomplish this a detailed system model was developed in TRNSYS 17, which includes a six-zone building model and the heat pump control. Moreover, these control strategies include short-term weather and price forecast services. Another objective is to evaluate the impact on the benefit of these control strategies in terms of energy use and economic performance for a wide range of boundary conditions (country/climate, electricity prices, occupancy and appliance loads). Results show that the control using a forecast of dynamic electricity price in most locations leads to greater final energy savings than those due to the control using thermal storage for excess PV production. The exception is Sweden, where the result is the opposite. Moreover, the addition of battery storage leads to greater decreases in final energy than the use of the thermal storage (TH mode), which is limited to the thermal mass of the building and small hot water tank of the compact heat pump. As far as the impact of the advanced control (combined use of TH and PRICE) on cost savings is concerned, savings (up to 175 €) are possible in Spain and in Germany. The design of the TH and PRICE mode show low computational complexity that can be easily implemented in existing heat pump controllers. Additionally, the PRICE mode should have no capital and running cost for the end user while the TH mode might require an external electricity meter. Another yet implication with the TH mode is the need to activate the room thermostatic valve.
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| 6. |
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| 7. |
- Sundberg, Klas, 1967-
(författare)
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Atlas Copcos strategi och styrning : Verktyg som ger guld
- 2009
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Licentiatavhandlingen analyserar den strategi och styrning som bedrivits vid Atlas Copco sedan 1980-talet. Detta ger kunskap om hur ett traditionellt svenskt industriföretag anpassar sig till en turbulent omgivning med hård internationell konkurrens. Atlas Copco är ett industriföretag med kompetenser omkring tryckluftsteknik, gruv- och anläggningsmaskiner och industriverktyg. Det har en komplexitet i strategisk inriktning, organisatorisk struktur och styrning som gör det lämpligt som studieobjekt inom forskningsprogrammet Strategi, styrning och konkurrenskraft (SiSK). Atlas Copco är ett klassiskt svenskt företag som under sin 136-åriga historia utvecklats till en global aktör genom de produkter och lösningar som skapats och erbjuds marknaden. Utifrån dagens verksamheter är det möjligt att spåra omfattande strategiska och organisatoriska förändringar som stegvis genomfördes från slutet av 1960-talet fram till inledningen av 1990-talet. Studien är retrospektiv där fallföretagets strategiska utveckling och styrning i efterhand studerats. Som utgångspunkt i analysen har valts en tentativ modell om strategisk kongruens och integrerad styrning. Avhandlingen bygger på insamlat material om företaget i form av årsredovisningar och andra skriftliga källor samt intervjuer med 25 nuvarande och tidigare befattningshavare vid företaget. Studien visar att fallföretaget kan uppvisa strategisk kongruens på olika organisatoriska nivåer och att denna kongruens stöds av en integrerad styrning som till sin karaktär är både formell genom traditionella system för ekonomi- och produktionsstyrning men också informell genom att en särskild kultur byggts upp runt företagets verksamheter och hur de ska bedrivas. Studien ger specifika implikationer för fallföretaget när det gäller strategi och styrning som är intressanta för andra företag och organisationer. Detta gäller särskilt hur starkt fokuserade verksamheter kan styras och utveckla långsiktiga konkurrensfördelar. Studien har finansierats av Jan Wallanders, Tom Hedelius och Tore Browaldhs stiftelser. Dessutom har finansiellt stöd erhållits från forskarskolan Management och IT (MIT).
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| 8. |
- Weiss, Philipp, 1981-
(författare)
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Simple Question, Complex Answer : Pathways Towards a 50% Decrease in Building Energy Use
- 2014
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Addressing building energy use is a pressing issue for building sector decisionmakers across Europe. In Sweden, some regions have adopted a target of reducingenergy use in buildings by 50% until 2050. However, building codes currently donot support as ambitious objectives as these, and novel approaches to addressingenergy use in buildings from a regional perspective are called for. The purpose ofthis licentiate thesis was to provide a deeper understanding of most relevant issueswith regard to energy use in buildings from a broad perspective and to suggestpathways towards reaching the long-term savings objective. Current trends inbuilding sector structure and energy use point to detached houses constructed before1981 playing a key role in the energy transition, especially in the rural areas ofSweden. In the Swedish county of Dalarna, which was used as a study area in thisthesis, these houses account for almost 70% of the residential heating demand.Building energy simulations of eight sample houses from county show that there isconsiderable techno-economic potential for energy savings in these houses, but notquite enough to reach the 50% savings objective. Two case studies from ruralSweden show that savings well beyond 50% are achievable, both when access tocapital and use of high technology are granted and when they are not. However, on abroader scale both direct and indirect rebound effects will have to be expected,which calls for more refined approaches to energy savings. Furthermore, researchhas shown that the techno-economic potential is in fact never realised, not even inthe most well-designed intervention programmes, due to the inherent complexity ofhuman behaviour with respect to energy use. This is not taken account of in neithercurrent nor previous Swedish energy use legislation. Therefore an approach thatconsiders the technical prerequisites, economic aspects and the perspective of themany home owners, based on Community-Based Social Marketing methodology, issuggested as a way forward towards reaching the energy savings target.
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