Climate change is expected to lead to changes in ambient temperature, wind speed, humidity, precipitation and cloud cover. As electricity demand is closely influenced by these climatic variables, there is likely to be an impact on demand patterns. The potential impact of future changes in climate on electricity demand can be seen on an hourly, daily and seasonal basis through the fluctuation of weather patterns. However, the magnitude of such changes will depend on prevailing electricity use patterns as well as long-term socio-economic trends. This thesis investigates how changing climate will affect Thailand’s short-term and long-term electricity demand. Its review of available literature across the climate change and power systems fields highlights that analysis of such impacts for developing nations is almost entirely lacking. It then presents a modelling approach to capture the influence of temperature on daily and seasonal demand. The models are initially used to examine the sensitivity of demand to uniform rises in temperature. More sophisticated modelling, based on temperature projections from the UK Hadley Centre climate model combined with socio-economic projections from the Intergovernmental Panel on Climate Change Special Report on Emission Scenarios, is used to project absolute changes in Thailand’s electricity demand across three future time periods. The specific climate and socio-economic scenarios considered here indicate that mean annual temperatures in Thailand will rise by 1.74 to 3.43°C by 2080, implying additional increases in Thai peak electricity demand of 1.5–3.1% in the 2020s, 3.7–8.3% in the 2050s and 6.6–15.3% in the 2080s. The implications of the changes are discussed in terms of Thailand’s approach to meeting future electrical demand.

This work examines some of the fundamental problems behind the control of wave energy converters (WECs). Several new perspectives are presented to aid the understanding of the problem and the interpretation of the literature. The first of these is a group of methods for classifying control of WECs. One way to classify control is to consider the stage of power transfer from the wave to the final energy carrier. Consideration of power transfer can also be used to classify WECs into families. This approach makes it possible to classify all WECs, including those that had previously eluded classification. It also relates the equations of motion of different classes of WECs to a generalised equation of motion. This in turn clarifies why some types of control are suited to some WECs, but not others. These classification systems are used to demarcate the boundary for the theoretical work that follows. The theory applies to WECs with governing equations of motion that are linear, and to control systems that are linear, aim to maximise power, and which regulate the PTO stage of power flow. Another important perspective is the new wet and dry oscillator paradigm, which is used to differentiate between frequency domain modelling and a commonly used technique, monochromatic modelling. This distinction is necessary background for many of the new ideas discussed. It is used to resolve an ongoing debate in wave energy research: whether frequency domain modelling can be applied to cases that are not monochromatic. It is the key to an extension to the theory of capture width, a widely used performance indicator. This distinction is also the rationale behind an improved method of presenting frequency domain results: the frequency responses due to both monochromatic and polychromatic forcing are represented on the same graph. These responses are different because the optimal control problem is acausal, a topic that is also discussed in depth. This visual tool is used to investigate and confirm various ideas about the control of WECs, and to demonstrate how the newly redefined capture width encapsulates the essential control problem of WECs. The optimal control problem is said to be acausal because information about the future is required to achieve optimal control. Another vantage point offered is that of the duration of the prediction interval required for optimal control. This is given by a new parameter emerging from this work, which has been termed the premonition time. The premonition time depends on the amount of knowledge required, which is determined by the geometry of the WEC, and the amount of information available, which is largely determined by the bandwidth of the sea state. The new perspectives introduced are the various systems of classification, the wet and dry oscillator paradigm, the presentation of monochromatic and polychromatic results on the same axes, premonition time, and the revised theory on capture width. These are all used to discuss the interrelationship between WEC geometry, the control strategy and the sea-state. The opportunities for, and limitations of, the use of intelligent control techniques such as artificial neural networks are discussed. The potential contribution of various control strategies and associated design principles is explored. This discussion culminates in a series of recommendations for control strategies that are suited to each class of WEC, and for the areas of research that have the potential to bring about the greatest reductions in the cost of harnessing energy from sea waves.

At present there is much debate about the impacts and benefits of increasing the amount of generation connected to the low voltage areas of the electricity distribution network. The UK government is under political pressure to diversify energy sources for environmental reasons, for long-term sustainability and to buffer the potential insecurity of uncertain international energy markets. UK Distribution Network Operators (DNOs) are processing large numbers of applications to connect significant amounts of Distributed Generation (DG). DNOs hold statutory responsibility to preserve supply quality and must screen the DG applications for their impact on the network. The DNOs often require network upgrades or DG curtailment, reducing the viability of proposed projects. Many studies exist that identify barriers to the widespread connection of DG. Among them are: suitability of existing protection equipment; rating of existing lines and equipment; impact in terms of expanded voltage envelope and increased harmonic content; conflict with automatic voltage regulating equipment. These barriers can be overcome by expensive upgrades of the distribution network or the expensive deep connection of DG to the higher voltage, sub-transmission network. This work identifies changes in network operating practice that could allow the connection of more DG without costly upgrades. The thesis reported is that adopting options for a more openly managed, actively controlled, distribution network can allow increased DG capacity without upgrades. Simulations have been performed showing DG connected with wind farm production time series to a representative section of the Scottish distribution network. The simulations include modelling of voltage regulation by network equipment and/or new generation. The cost and effects of the consequent network behaviour evaluated in monetary terms are reported. Alternative control strategies are shown and recommended, to reduce DNO operation and maintenance costs and the cost of connection to the developer with no reduction in supply quality.

This thesis was conducted to study Bertegruppens vision of being a business group self-sufficient on electrical energy. The scope was to investigate the potential of the vision being realized in a near future by adding solar energy to the existing energy production mix. Examinations of the energy need and the consumption pattern at the different companies were made by studying hourly data from the electricity supplier. Future energy need was determined during interviews and study visits, where potential areas for solar modules also were identified. Global solar radiation data was collected fromthe STRÅNG model, provided by the Swedish Meteorological and Hydrological Institute. These data were inserted to the micro power simulation tool HOMER ENERGY, along with solar module parameters from a solar energy installer Bertegruppen has initiated discussions with. The simulations resulted in potential solar energy production for a maximized and an adapted case for each company. In the adapted case, the implications from the Swedish solar energy market were considered while in the maximized case they were not. The simulation output data were then processed in the computational tool MATLAB, along with the hourly data over the electrical energy consumption at each company. At last economical calculations were carried out for the maximized and adapted case for each company, based on the Levelized Cost of Energy method. By adapting the maximized solar cell systems at each company, expand the hydropower station according to the plans, add diary-residues from Sia Glass to the biogas plant and account for the electrical energy bought from other hydropower stations in Suseån within the guarantees of origin system, Bertegruppen would produce 50.8 percent of their electrical energy need in 2021. For the adapted solarcell systems, the share would be 46.3 percent. The maximized solar cell systems resulted in a LCOE of 0.522 kr/kWh for Bertegruppen at a present value of 1 934 tkr.The LCOE for the adapted solar cell systems would be 0.529 kr/kWh at a presentvalue of 823 tkr.

In this master thesis project, conventional supermarket refrigeration systems using R404A are compared with refrigeration system solutions using natural refrigerants such as carbon dioxide and ammonia. This systems analysis considers the behavior of those systems in floating condensing and heat recovery mode. System heating and cooling COP have been calculated by using computer simulation with the calculation software EES (Engineering Equation Solver). The impact of important parameters such as sub-cooling, external superheating and compressor discharge was also determined through the computer models.The estimation of the system annual energy consumptions shows that systems using natural refrigerant can compete with systems using artificial refrigerant by using heat recovery system such as heat pump cascade, heat pump cascade for sub-cooling, fixed pressure system and de-superheater. If the indirect emission of systems using natural refrigerant and artificial refrigerant is approximately similar, the direct emission for carbon dioxide systems and ammonia systems can be estimated to be 10000 times less important than R404A systems.Multi-unit refrigeration systems have also been studied in this project; it appears that in theory COP improvement of 10% is possible if the condensing temperature of each unit is controlled adequatelly. / B

A society with interconnected energy sectors may be a contributing factor to reduce carbon dioxide emissions, while simultaneously meeting the increasing demand for electric energy. This study investigates the possibilities to link a sea-based wind farm with hydrogen gas production in addition to serving as a support function to a transmission systems operator. Using a custom-built model, this interconnected system is simulated for different scenarios where the wind farm, electrolyser and the balanced power market are observed. The model takes into account the economic potential and the different ways of producing hydrogen gas, while also discussing the potential significance of interconnected systems such as this.  The result indicated that the economic viability in constructing an interconnected system such as the one included in the study is substantially dependent on the variability of the price for electricity. It is also concluded that out of the modelled scenarios, two could be considered to have the possibility to become economically viable. One case consisted of an electrolyser being fed electric power directly from the wind farm, where the system was constantly available to act as a support system to the power grid. The other scenario considered viable based on the results was when the electrolyser was fed with electric power from the grid and set to be available to run while the spot price was below a threshold value.  While the parameters used for sizing the system in the model cannot be considered to be optimized in all cases, the size of the electrolyser did not significantly affect the result of the simulated scenarios.

Global warming and associated role of energy consumption across various sectors is a well-researched topic in recent years. Understanding current urban energy consumption patterns will allow us to understand how future energy consumption patterns will evolve. With electrification of vehicles and potentially altering culture of work from home, the energy usage at regional level would see a significant change in the future. The current PhD dissertation contributes to energy consumption analysis of a region by analyzing residential energy consumption, commercial energy consumption and transportation energy use by households. The aggregation of these energy consumption within a region contributes to the total energy consumption of a region. As the share of electric vehicles increases, the proposed modeling frameworks provides the current consumption that serves as a baseline estimate. Specifically, for the energy consumption, we examine the choice of energy sources and the energy consumption by source. The share of electrical vehicles is currently increasing. As the share of electric vehicles increases within our transportation infrastructure, the spatio-temporal nature of current electricity demand is likely to alter with increased household electricity consumption for vehicle charging. To develop a future estimate of urban demand with electric vehicles, a model system of current consumption serves as a baseline estimate. The analysis of energy use in residential buildings and commercial buildings is conducted using Residential Energy Consumption Survey (RECS) and Commercial Building Energy Consumption (CBECS) datasets. The transportation energy use is analyzed using National Household Travel Survey (NHTS) and MPG of the vehicles taken from Vehicle Fuel Economy Estimates. Multiple Discrete Continuous Extreme Value (MDCEV) model and Joint Binary Logit - Fractional Split Model (Joint BLFSM) are used to analyze residential energy consumption. While Bi level MDCEV is used for commercial energy use and spatial weighted regression models are used to analyze transportation energy use.

The goal of this project was to construct a model of a microgrid to avert possible power disruptions. The microgrid should provide electrical energy to four essential facilities; a nursing home, a gas station, a preschool and a fire station. The simulations were performed on the assumption that the microgrid is self-sufficient and thereby has its own energy production and storage. The potential of the solar cells, as an energy source, was investigated in the simulation model. A biogas turbine was considered to compensate for the months when the energy production is less than the demand.  Energy storage in the form of a lithium-ion battery was also included in the simulation model. The battery was designed to operate immediately after a power outage. According to the simulations, the installed solar cells did not generate enough electrical energy to satisfy  the energy needs in the facilities during autumn, winter and spring. If a storm strikes during these seasons, Knutby will have insufficient power. The system has been deemed insufficiently resilient when the system is off-grid. However, if this system is combined with a backup power source, it will be more resilient. The solar cells would provide electrical energy during the summer and the backup power supply would handle any emergency situations during the rest of the year. Biogas is produced locally at Kungsängens gård and will therefore make the system more resilient  If the aim and/or use of the microgrid were to be changed, the choice of energy production and energy storage might be altered to satisfy the given purpose.

<p>This thesis will discuss a novel method of tracking the Sun. An essential aspect of the method is to rotate a polar aligned single axis tracker such that the angle between the direction of the Sun and the normal of the module remains at a constant angle of 23.44 degrees or a few degrees more. The rotational symmetry that arises from this circumstance enables seasonal tracking to occur inside the module whilst maintaining efficient concentration. Several possible optical designs and a preferred optical design are presented as a way of implementing the tracking method. The tracking method is also open to a plethora of different concentrator photovoltaic system designs which may be integrated onto rooftops more effectively than conventional dual axis tracking systems.</p> / Master of Applied Science (MASc)

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