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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.

Energy Storage on the Grid and the Short-term Variability of Wind

Hittinger, Eric Stephen 01 August 2012 (has links)
Wind generation presents variability on every time scale, which must be accommodated by the electric grid. Limited quantities of wind power can be successfully integrated by the current generation and demand-side response mix but, as deployment of variable resources increases, the resulting variability becomes increasingly difficult and costly to mitigate. In Chapter 2, we model a co-located power generation/energy storage block composed of wind generation, a gas turbine, and fast-ramping energy storage. A scenario analysis identifies system configurations that can generate power with 30% of energy from wind, a variability of less than 0.5% of the desired power level, and an average cost around $70/MWh. While energy storage technologies have existed for decades, fast-ramping grid-level storage is still an immature industry and is experiencing relatively rapid improvements in performance and cost across a variety of technologies. Decreased capital cost, increased power capability, and increased efficiency all would improve the value of an energy storage technology and each has cost implications that vary by application, but there has not yet been an investigation of the marginal rate of technical substitution between storage properties. The analysis in chapter 3 uses engineering-economic models of four emerging fast-ramping energy storage technologies to determine which storage properties have the greatest effect on cost-of-service. We find that capital cost of storage is consistently important, and identify applications for which power/energy limitations are important. In some systems with a large amount of wind power, the costs of wind integration have become significant and market rules have been slowly changing in order to internalize or control the variability of wind generation. Chapter 4 examines several potential market strategies for mitigating the effects of wind variability and estimate the effect that each strategy would have on the operation and profitability of wind farms. We find that market scenarios using existing price signals to motivate wind to reduce variability allow wind generators to participate in variability reduction when the market conditions are favorable, and can reduce short-term (30-minute) fluctuations while having little effect on wind farm revenue.

Design And Simulation Analysis of a BIPV (Building Integrated With PV) Air-Duct System for Residential High-Performance Development

Zarmehr, Arash 01 January 2023 (has links) (PDF)
A growing number of buildings are integrating building-integrated photovoltaics (BIPV) devices to increase energy efficiency and reduce energy costs. A building's heating and cooling loads are impacted by the thermal resistance of the air duct BIPV because of the change in thermal resistance. Therefore, augmenting the efficiency of (BIPV) devices will benefit many building architectures and mechanical engineering applications. This work introduces a low-cost and low- maintenance air duct system design augmenting BIPV systems. This novel approach increases airflow velocity and decreases air temperature for BIPV, resulting in improved performance for the PV system electricity output, increased PV lifespan due to reduced temperatures, and improved overall energy efficiency of the building. Specifically, we show how to model and simulate the BIPV system analyzing both the PV devices and building energy. We present a quantitative study to demonstrate this air duct system can reduce energy usage by up to 2.7% depending on the climate zone. The air duct system performs best in warm and sunny climates based on our simulations. Finally, we use computational fluid dynamics (CFD) to study the additional advantages of this air duct model. Due to the lower temperature of the PV surface, the results indicate that air ducts can improve the electrical energy production of PV modules by up to 3%. This benefit is not limited to energy production; it will also contribute to a longer life cycle for PV modules by lower temperature-induced degradation. Lastly, our study simulates a wide variety of parameter options to understand the optimal design integration of the BIPV system's impact on a building's energy loads.

An open source approach to Sweden's energy system : A review of future energy pathways

Nawfal, Saadi Failali January 2013 (has links)
This paper discusses the development of an energy systems model for Swedenconsidering electricity, heat and direct fossil fuel consumption in the residential,industrial and transport sectors as well as the energy interaction with the other Nordiccountries and its impact on the Swedish energy system. The model is developed in theOpen source energy modelling system (OSeMOSYS) (Mark Howells 2011) andshowcases potential energy investment options for Sweden in the next four decades(2010-2050). It considers different scenarios and provides a technology neutralassessment of how Sweden can invest in energy infrastructure in the most judiciousway. The paper also describes the new user interface developed called ANSWEROSeMOSYS.The paper further discusses the results of the different scenarios. Thebusiness as usual scenario shows an inclination towards investments in nuclear power.Further scenarios consider the gradual phasing out of the use of oil in CHP plants andnuclear power as well as new energy policies and tax reforms. The paper discusses theseresults in detail and demonstrates how Sweden could improve its energy infrastructureconsidering different policy implications and constraints put up by the availability andfeasibility of different resources. Finally, the prospect of wider stakeholder engagementbased on this model is discussed. Building on the open-source nature of the model,inputs and modifications from research institutes, energy modelling experts,government bodies, as well as the wider public will be incorporated into the model. Thesource code and modelling data will be made publicly available.

Prospects for renewable Hydrogen in the implementation of the EU hydrogen strategy in Sweden and Spain : An analysis of stock market companies

Contelles Rodriguez, Sergi January 2022 (has links)
The future energy transition will reshape the current fossil energy system with low-carbon energy sources. The new technologies and State policies will promote the implementation of different energy carrier sources such as electricity, ammonia, biomass and hydrogen. However, volatility, uncertainty, complexity, and ambiguity are defining a new global framework for energy systems. Despite Covid-19, the Russian and Ukrainian war, among other disruptive events, the pursuit of zero emissions remains one of the ambitions of the European Union, and renewable hydrogen has been selected to achieve these goals. The European Union through its Hydrogen Strategy aims to scale the hydrogen energy system based on renewable hydrogen in the coming years. For the present analysis, Sweden and Spain have been selected and it has been verified how the energy baseline, the national hydrogen strategies, and the main companies will shape the future hydrogen energy system of both countries. The selected method was a holistic qualitative and quantitative analysis of the energy systems of Sweden and Spain, focusing on the interactions inside and outside the energy system at the national level. The national strategies, the energy background of the countries, and the investments from the OMX-Stockholm30 stock exchange for Sweden and IBEX-35 for the Spanish case were analysed. Only bibliographic sources, internet news, and public reports from brokerage houses were used as material. The main results of the work show two very different ways of implementing national hydrogen policies. On the one hand, Sweden has high ambitions to produce renewable hydrogen up to 5 GW from electrolysers by 2030. Sweden is currently focusing its hydrogen energy system on renewable hydrogen steelmaking projects such as HYBRIT or GreenSteel. On the other hand, Spain has a lower national ambition with only 4 GW of electrolysers by 2030 according to its national roadmap. However, the IBEX-35 companies have already planned more than 13 GW of electrolyser capacity with the Catalina, SHYNE, HYDEAL projects, among others. The main investments will focus on sectors that are difficult to abate, such as oil & gas and fertilizers, and with the participation of the steel industry.

The impact of climate change on electricity demand in Thailand

Parkpoom, Suchao Jake January 2008 (has links)
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.

New perspectives on wave energy converter control

Price, Alexandra A. E. January 2009 (has links)
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.

Voltage management of networks with distributed generation

O'Donnell, James January 2008 (has links)
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.

Investment analysis for solar PV cells in Sweden

Wollein, Jonathan January 2017 (has links)
No description available.

Adaptation of Solar Energy Driven Absorption Chillers for Air Conditioning in Commercial Building

Kalinga, Ranjith Shantha De Silva January 2017 (has links)
The most recent analysis of energy usage in the country reveled that nearly 50% of the power generation is used for air conditioning and mechanical ventilation most of which is used by commercial organizations. The grid generation mix that contains a high percentage of fossil fuel makes such energy usage environment unfriendly. Although absorption refrigeration is an old technique its economical application is limited to applications where cheap or waste heat energy is available despite decades of R&D, due to low COP, high initial cost and larger size. Heat input at Moderately high (over 120ᵒC) temperature and need to release large amount of heat to the environment through liquid or air cooling makes absorption chiller less conducive in cooling. Yet, being a tropical country, Sri Lanka has a better potential in adopting solar driven absorption refrigeration, if the chillers are operated at low temperature heat input that also promotes efficiency in storage that is mandatory due to fluctuation of energy source, subject to economic feasibility. The project aims designing and modeling of a solar power driven absorption chiller system that is adoptable to a selected medium size commercial organization. The proposed system uses heat energy around 100ᵒC and reusing fraction of energy expelled to the environment by suitably modifying operating parameter and thereby increasing efficiency of the system. Reduction of such heat losses and reducing heat input is achieved with the use of secondary heat exchange (brine) system that optimizes the energy usage. This arrangement will make efficient usage of solar heat storage, even in the considerable absence of solar power. System modeling and simulation of both basic double effect chiller and its modified versions were carried out and compared to evaluate improvement. The simulation of the modified system was used to obtain working parameters of the chiller so that a suitable solar collector, chilled water and heat rejection systems can be designed. Operational conditions of the cooling system are measured by the state sensors that feed inputs to the control system to achieve the optimum efficiency and their technical details are also included in the report.

Test Grids for Reliability analysis : Analysing interruptions and developing test grids based on Mälarenergi Elnät distribution grid

Eld, Jonas, Melin, Jens January 2017 (has links)
The purpose of this degree project is to examine power outages that has occurred during the years 2009 and 2016 on Mälarenergi Elnät distribution grid. Interruptions that has occurred on 10 kV voltage level and on overhead lines or underground cable was examined. The examined interruptions are based on the DARWin data from Mälarenergi Elnät. The examined interruptions resulted in four different test grids. Test grid A are overhead line grid in rural area, test grid B are mixed grid in rural area, test grid C are underground cable grid in semi urban area and test grid D are underground cable grid in urban area. Test grid C and D which have the highest customer density were then used for reliability analysis. The reliability analysis was performed using Microsoft Excel. The main focus for the reliability analysis were the impact of different sectioning times. Another focus for the reliability analysis was introducing breakers at key-points in test grid C. The primarily cause of interruptions on overhead line grids are weather related events and on underground cable grids it is digging and fabrication or material errors. It is concluded that with quicker sectioning times, the reliability of the grid increases linearly. The introduction of breakers at key-points in the grid results in increased reliability.

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