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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Lågtempererade uppvärmningssystem och dess potential i nybyggda och energieffektiva kontorshus : En studie i att använda returtemperatur från befintlig bebyggelse till uppvärmning

Gustafsson, Johan January 2018 (has links)
This master thesis examine how a low temperature radiator systemcan be implemented in a new built office and what effects this will have on the return temperature. One point in the system was logged and data was collected. A model was then developed in VIP-Energy to determine the heating demand for an office building which were compared to the supply. A cost analysis was also performed on different types of low temperature radiator systems. These were compared to a conventional radiator system with a supply temperature of 55°C and a return temperature of 45°C. A cost analysis was also done on whether to build energy efficient or not. The study shows a strong correlation between the heat demand and the time of day. The demand is low during office hours and high during nights and weekends with a peak demand of 70 kW. The low demand is due to the high amount of process energy an office uses. The point in the system can supply the heat demand during almost every hour of the year. For the few hours where there is a mismatch between supplied heat and demand, a shunt solution can supply the return water with primary heat. If the heat demand is scaled up with ten or twenty identical houses the point will be unable to supply enough power to cover the heat demand for more hours a year. The most cost-effective radiator system is Purmo Belize with a supply temperature of 40°C and a return temperature of 30°C. Purmo Belize has built in fans that can improve the heat supply to the room with up to 80 %. Compared to a conventional radiator the payback time is 9 years, with a return on investment of 12,8 percent and a net present value of 151 762 kr. A 40/30°C-system will lower the return temperature in the measured point with 0,4°C. For the whole system this means a reduced temperature of 0,00003°C if the total flow is 50 m3/s and the average return temperature is 50°C. From a strictly economic point of view, an extra energy efficient house will be beneficial if the extra cost is up to 5 000 000 kr or around 700 kr/m2 with a depreciation time of 25 years.
22

Simris lokala energisystem

Berkan, Yaroslav January 2018 (has links)
No description available.
23

Självförsörjande småskaliga ’off-grid’ nät, baserade på sol- och vindkraft i kombination med pumpkraftverk / Small scale selfsustained “off grid” systems based on solar and wind power combined with pumped hydro energy storage

olof, eriksson January 2018 (has links)
No description available.
24

Design av solcellsanläggning för strömförsörjning för Falkenbergs nya bibliotek

Sami Kasim, Ayvar January 2018 (has links)
Every life on the earth is addicted of the sun. The sun is clean and free energy source. In Sweden there is a long term goal for the global energy system with 100% renewable energy. To achieve this goal we need more efforts in a form of including solar cells. Solar cells has existed a long time on the markets, but in the recent years it has been more interesting in the world and it is mainly because the price has gone down, the quality has been better, the efficiency has been higher. Nowadays people are more interested to do something that is environmentally friendly and profitable. Because of the solar cells are applying good on the roofs and facades so the property companies have been more interested to place solar cells on their buildings. My project is about potential electricity generation for photovoltaic systems at the new library roof that will be built in Falkenberg. In my work I explain what a solar cell is, how it works, how many types are there and what kind of it is the most common, how solar systems work, how it is installed, what it takes to install solar cells, and what it provides for power. After I have tested different angles as solar modules are directed against, comparisons and calculations, the results of the design have shown that the roof of the library has good opportunities for mounting solar cells installations. The best angle was 27◦ to the south with azimuth 185◦. The conclusion of the work is that it is profitable to invest solar systems at the library's roofs. Repayment time is long but it is worth it, in this way Falkenberg’s government also makes an effort for the environment.
25

Application of a mathematical approach in modeling wind time series : A general survey of the Langevin method

Jalaei, Fatemeh January 2015 (has links)
Today, the great importance and benefits of renewable energies as a source of endless energy is obvious for all. Wind is recognized as one of the most stable and safest type of energy, due to ease of access as well as applying modern technical and scientific methods in order to its extraction. In this regard, much effort has been done in the developed societies to obtain knowledge besides getting access to new techniques in the exploitation of this unlimited wealth. Apart from the new aspects of the proposed research in wind area, the extraction operation requires specialists to advanced techniques and scientific research. The development of societies and their increasing necessity to energy resources have increased the importance of safe and clean renewable energy. This study investigates a technique to specify the power performance of the wind turbine directly from measured data which fluctuate with high frequency. This project is a review of a dynamical method for the specification of wind turbines' power curves. Considering the power output of a wind turbine in this study, the basic concept is to divide its dynamics into two components; a deterministic(relaxation) and a stochastic(noise) functions which are equivalent to the wind turbines' real behavior itself and the exterior wind turbulence. It specifically presents a procedure to estimate the reaction of the wind turbine as a machine to the wind speed dynamically. In this method, reconstruction of the coefficients from the measured data and extraction of the specification of the power output have been done. The main focus of this technique is on differential equations which are recognized as Langevin equations. As the consequence, it is shown; with this method we will be able to percept the conversion dynamics of wind turbines and get the power curves' results with high precision. The results demonstrate that power performance's specification is accurately reconstructed from the measured data by the quick estimation of the coefficients from data. Furthermore, the high accuracy and fast estimation of the power curves would be considered as preferences in this method.
26

Miljökrav på solceller : En utredning om koldioxidutsläpp från kristallina kiselsolceller / Environmental requirements on PV : A study on carbon dioxide emissions from crystalline silicon PV

Vanky, Kristin January 2018 (has links)
This master thesis is an investigation of environmental sustainability of photovoltaic (PV) modules. The purpose is to examine how purchasers of PV systems could put requirements on the modules so that their life-cycle carbon dioxide emissions reduces in the most effective way. The purpose is also to survey environmental third-party certifications for solar modules. Only mono- and multicrystalline silicon modules are considered. In the first part of the thesis, the carbon dioxide emissions from the manufacturing and transportation of different modules are calculated. Furthermore, the solar electricity production is simulated in the software PV syst. Modules with different peak power capacity, origins and manufactured with different techniques are compared. In part two, recycling techniques and regulations for management of end-of-life-modules are investigated. The number of end-of-life modules based on Solkompaniet Sverige AB´s historical installations are estimated and out of these, their potential economic value, based on two different recycling scenarios, is calculated. According to the results, monocrystalline modules cause higher emissions than equivalent multi-crystalline from the same manufacturer. Modules with the same peak power and silicon but with different origins and silicon manufactured with different technologies, produce about the same amount of electricity, but show a large variation in carbon dioxide emissions, mainly due the electricity consumption and the characteristics of the electrical mix used in the manufacturing process. The modules’ operating time in addition to pre requisite conditions for mounting are crucial for thee missions per produced kWh electricity, contrary the transports have very little effect on the total emissions. Carbon dioxide emissions could be reduced through re-usage of elements from recycled end-of lifemodules, particularly aluminum and silicon, but economic factors hinder this today, mainly due to too few end-of-life modules. Silveris the most expensive element in a module. The value of end-of-lifemodules will decrease by decreasing silver content, but overall increase due to increased waste volumes. The future economic value of end-of-life modules is hard to estimate, but could be crucial for the possibility to take advantage of the environmental benefit from treatment of end-of-life modules. In order to reduce carbon dioxide emissions from solar modules, requirements should be directed towards the module manufacturing process. This thesis emphasizes pre requisites expected to give lower emissions, hence modules that are more likely to cause lower environmental impact than others. To be able to develop specific requirements, more transparent and reliable energy consumption data is necessary. It exists very few, and no Swedish environmental certifications specifically designed for solar modules. The ranking list Solar Scorecard is not a certification but seems to be the most used in order to demonstrate manufacturers' environmental performances.
27

Termisk lagring vid Akademiska sjukhuset : Kapning av effekttoppar, ökad redundans och energisäkerhet

Ohlsson, Pontus January 2018 (has links)
The Academic Hospital in Uppsala is a major heat energy consumer with an average consumption of 39 GWh/year in recent years, and the heat is supplied by the district heating system which is owned by Vattenfall. The purpose of this work was to investigate if a thermal storage can reduce the costs of district heating consumption and increase the redundancy at the hospital by cutting the heat demand peaks and provide back-up heat in case of district heating deliverance failures. The type of heat storage used in this study is a pit heat storage which consists of an insulated basin in the ground filled with hot water which is sealed from above with a lid that acts as an insulating layer. Matlab was used for the simulations of different storages sizes and used year 2016:s heat consumption of the hospital building B11 to see how the storage worked. The introduction of a thermal storage will increase the total sum of purchased heat for all storage sizes and the two larger storage sizes manage to cut down the heat demand peak while the two smaller storage sizes increases it slightly. This means increased annual costs for the smaller storage sizes but reduced annual costs for the larger storage sizes. However this doesn’t included the drift or the investment costs. The conclusion is that heat storage is not an economic benefit because the annual cost savings are highly dependent on Vattenfall's price model and the repayment period will be several decades long. A heat storage can be an energy-saving benefit but at a high cost.
28

Road map of the ultimate sustainable bio-fuel production from microalgae

Idris, Lina January 2015 (has links)
No description available.
29

FEASIBILITY STUDY OF BUILDING INTIGRATED HYBRID SOLAR PV AND WIND POWER SYSTEMS: A CASE-STUDY ON THE SWEDISH ISLAND OF GOTLAND

Lee-Jones, David January 2016 (has links)
This Thesis carries out a high level analysis of the financial feasibility of building integrated small scale renewable energy systems. A number of alternative system configurations have been established that include a mixture of grid connected wind turbines and solar photovoltaic (PV) applications to provide electricity to meet the demand of the base load demand of the building, with any occurrence of excess production sold back to the grid. A methodology to account for an analysis of their feasibility has been developed. The methodology is based on a well-known clean energy system analysis tool, namely RETScreen. The local climate data has been extrapolated and calculations carried out using the RETScreen database and software. From this, the maximum initial financial investment of the systems has been estimated, based on a given financial hurdle rate (i.e. the annual financial interest return on initial investment) and the savings and income generated from reduced grid electricity consumption and selling electricity back to the grid. The methodology is applied to an academic building located in the city of Visby on the Swedish island of Gotland, with a hurdle rate set to 7%. Electricity generation scenarios include 4 systems with 3.6 - 15.2 kW of wind, and 21.5 kW of PV located on a flat roof of a building containing office space, lecture rooms and a large student break area. Of the considered systems, it was concluded that the most feasible system was the system with a mixture of 15.2 kW of installed wind capacity and 21.5 kW of installed solar PV capacity. In addition, the results suggested that even with the grant system in place in Sweden for solar PV systems, the solar PV part of the systems would likely not be feasible. Therefore it was suggested that future work in this area should involve an investigation of a purely wind power system be carried out, as well as to investigate the hourly demand of the building and the hourly potential supply of the renewable energy system. The building permit process, installation and energy resources and requirements and installation should also be researched further, including taking actual energy consumption readings from the building and installing climate measuring instruments in the proposed positions on the roof in order to achieve more accurate input data.
30

A Disaggregation Model for Studying Behaviours in Power Consumption

Wik, Ellika January 2017 (has links)
A feature of the Smart Grid is the utilization of flexible load in the power system. The presence of flexible load allows part of the power consumption to be shifted from peak hours to off-peak hours; this change in power consumption is called a load shift. If the usage pattern of appliances is identified, it is possible to estimate the capacity of a potential load shift as well as evaluate if the utilization of flexible load in the power system results in a load shift. This master thesis project aims to create a model which works as an aid when studying usage patterns by identifying when appliances that contribute to the load shift are active. The model should be able to give approximations of the switch-on and switch-off time of the appliances using only information from a single meter that measures the total power consumption of the entire household. Recently, artificial neural networks have been successfully applied to these kinds of problems. The constructed model thus includes neural networks which regress the start time and end time of a target appliance. The networks are trained and evaluated both on simulated data and on real measured data from the Stockholm Royal Seaport project. The model is able to give highly accurate estimates of the start and stop time when trained with simulated data. When using real data the accuracy of the model is relatively low. In order to increase the performance the neural network part of the model has to be trained on a larger dataset. A study of how the sampling time of the input affects the performance of the model is also carried out. The results show no evidence that the sampling time affects the accuracy of the model. However, the architecture of the neural networks trained to recognize data with different sampling frequencies are not identical; if the pooling layers of all networks were removed it might be possible to establish a connection between sampling time and performance.

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