Renewable Energy Systems (M. Sc.)
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The offshore wind industry is flourishing year by year and the operators are dealing with the respective challenges affecting the lifespan of the offshore wind turbines. For this purpose, a thorough acquaintance with the vulnerabilities and related failure modes in the offshore wind turbine components is the first step to encounter and tackle the problems.
However, both the offshore and onshore wind turbines generally experience the same failures, the specific conditions in offshore cases such as salty and corrosive environment, wind gust, etc…, can accelerate these failures and affect the service life of the components. Accordingly, precise investigations of the main failures in the offshore environment are necessary to recognize the causes and mechanisms of these failures and protect the system from them.
In this research, the critical failure modes in offshore cases are investigated besides their causes and mechanisms, as well as the most critical components are discussed to determine the share of each of them in the total failure rate for offshore wind turbines.
Due to different reasons, cities are continuously changing in terms of technology, infrastructure, Internet of Things (IoT), strategy and are increasingly challenged to improve their competitiveness. With the speedy expansion in the metropolitan area, climate change problems are also increasing. The concept of a smart city was invented to address all the challenges what cities are facing. A Smart city target is to plan a city to provide primary resources like infrastructure, health care, secure food supply, energy, but at the same time; it also needs to make sure that overall economic, social, and environmental sustainability and include citizens with good quality of life, both sustainable and environmentally helpful by decreasing the carbon footprint. A smart city is distributed in three main components, a smart physical infrastructure, a smart digital infrastructure, and a smart community infrastructure. Smart cities components are explained with the targets and future research on different components with examples. Existing and developing smart cities such as Masdar City, Amsterdam, and Singapore are explained with the vision and strategy.
Fossil fuel will be empty shortly, and with having this in mind, Renewable energy sources are the key parameter for smart city development. The smart grid utilizes the power in more advanced technology with fewer power losses, and it also gives them the freedom to integrate different renewable energy sources and divide them into different microgrids for better power efficiency. A detailed Hybrid Microgrid (HMG) model has been simulated in the MATLAB/Simulink 2021a environment. The proposed model contains the different distributed energy resources such as photovoltaic, battery energy storage system, doubly fed induction machine for a wind turbine, transformers, and different controllers. Furthermore, It consists of AC and DC buses with different types of load at two voltage levels. The proposed model results are being analyzed in two scenarios. The proposed model will provide a base case for other future studies such as reactive power compensation, optimization, energy storage strategies, fault-tolerant control, stability and inertia analysis, demand response studies, hierarchical control.
This research work will be focused mainly on the design, operation, and control of microgrids for both grid-connected and off-grid operation. The research will then be integrated with the project work focusing on an active distribution networks predominantly microgrids with renewable energy sources to deliver low voltage power systems and loads. Microgrids as a distribution network will be introduced and the interrelation and the interoperability between the components of a microgrid will be discussed. Selection criteria for the components will be elaborated and a general guideline will be developed for the sizing, designing and integration of the components for a microgrid. The designing guidelines will be utilized for developing a suggested design for the related project work. Moreover, for the major equipment of the microgrid, a viability structure will be setup by the technical and financial analysis based on some basic market research, cost analysis and availability and capacity evaluation. In addition, demand response and market models will be analyzed focusing on the project site to form demand side management yardstick. The monitoring structures and control strategies were researched expressively along with a market research for the monitoring components. Finally, some operational microgrid project will be discussed as case studies in order to get a practical view of the research work for a better understanding.
Building integrated and ommunity photovoltaic systems to support the e-mobility infrastructure
(2021)
The sustainability of technology is one of the crucial factors on which the long-term use of the technology drives. Mobility is a vital part of the human species due to this from the 19th century; after introducing the first fossil fuel-based vehicle, technologies are developed around using these fossil fuels efficiently.But as the population is growing and more people can afford the cars as mobility source, a significant increase of fossil fuel is an issue, it has an immediate impact is on environmental issues like global warming.
The current trends in the automobile industry are towards the research and development of sustainable e-mobility technologies. Hence, it impacts the power industry to develop clean energy sources to support these technologies. The current automotive and battery technologies do not support the cause entirely due to technological constraints. Hence, the power engineers’ responsibility to support the current automotive technologies by supplying the Power on-demand using renewable technologies using photovoltaics sources.
Building the various charging nodes is considered to power the e-mobility by analyzing current trends and habits of using traditional mobility technologies. These nodes can be single-family houses, offices, shopping complexes for small cars. The hypothesis is made on the various scenarios and locations considering the financial aspects giving the exact idea of the infrastructure’s sustainability to be developed or already available. The advantages of using charging at source are needed to be discussed and further supported using renewable technologies to reduce fossil fuel consumption to generate electricity. This includes statistically analyzing the pattern of using the cars by an individual, further using this data to design a small-scale and economical BIPV bases solution fully or partially supporting the mobility cause. In this research, a car’s consumption data is analyzed and then compared with the typical PV system designed as per the lowest available space and budget. The system is further technically and commercially analyzed,to get a brief idea of the sustainability of the system.
In recent time, the popularity of hydrogen has considerably increased. As a fuel, hydrogen generates a considerable amount of energy with clean water being its only by-product. Green hydrogen could help decarbonize several industries as long as its supply chain is powered by renewable energy sources.
Hydrogen is a versatile fuel that can be used for long-term storage as well as for immediate consumption. Unlike fossil fuels, the chemical reaction of hydrolysis is reversible, meaning that electricity can be used for hydrogen production which in turn can be used to generate electricity again. This principle has given rise to the concept known as “Power-to-X”.
Chile has high solar irradiation levels in the north of the country, which allows for very cheap solar energy to be produced. Leveraging this and the wind potential
The purpose of this thesis is to analyze the impact of the integration of variable renewable energy sources (wind and solar PV) into the energy mix of smart cities and, in extension, smart grids. The thesis commenced with a review of scientific and industrial literature on smart cities, different energy generation sources, and energy storage technology's role in grid integration of variable energy source
With the high percentage penetration of intermittent renewable energy power plants in the power system, a significant challenge has emerged to balance the demand side and supply side. To keep the stable power system needs the coordination of various units, such as the generation side. For example, the power system frequency may cause rapid decline due to the connection of large loads. In the past, the conventional power plants played prominent roles in providing the residual load to the fast response to support the power system frequency. Nowadays, renewable energy power plants, such as wind power plants and solar photovoltaic power plants, are considered potential response units to participate in the power system. However, different power plants have different attributes, such as the startup time from cold status to the minimum load, from set point one to set point two. Therefore, classifying the power plants into appropriate levels is significant. In this thesis, the literature review regarding the power system's flexibility factors has been studied. The appropriate class of each power plants according to response time has been defined into primary response, secondary response, and tertiary response. Meanwhile, the typical power plants at present, such as thermal power plants, hydropower plants, wind power plants, solar photovoltaic power plants, biogas power plants, and energy storage facilities, have been researched. The average startup time and ramp rate of each power plant have been investigated. Moreover, the simple simulation of wind turbine pitch angle control based on the MATLAB/Simulink has been conducted. Finally, the classification of different power plants has been concluded based on their specific attributes. Furthermore, the solutions of improving the flexibility of conventional power plants are considered as the future work. At the moment, the outlook for the development of renewable energy and energy storage have also been described.
The application of voltage reduction in medium and low voltage grids has been implemented since the 1980s using several approaches. Conservation Voltage Reduction (CVR) as one approach in the Volt/Var Optimization (VVO) scheme uses on-load tap changers (OLTC) on Voltage Regulated Distribution Transformers (VRDT) to reduce or increase the voltage setpoint, thereby reducing the amount of active and reactive power supply in a network. A top-down estimation approach was applied in this research, using measurement data from substation transformers.
In this research, random tap changes were deduced from a set of annual measurements of voltage and power, and using a direct method, a CVR factor ranging from 0,95 to 1,31 was obtained. Using a continuous voltage reduction protocol over a one-month period, a CVR factor for energy and energy savings of 0,71 and 3,69% was obtained, respectively. In the end, proof for the validity of the results from the power demand reduction by testing various scenarios, hypotheses and isolating the impact of PV integration on the network was presented.
Revolution of the fully transparent luminescent solar concentrators and its impact on the world
(2021)
Rapidly increasing demand in energy allows room for constant improvement in renewable energy generation technologies. Solar energy usage is likely to increase even more in the recent years since the sun provides enough energy just in one hour that is sufficient to supply for whole humanity’s energy requirement in one year. This study initially explains the history of solar cells as well as how they function by utilizing the sun’s wavelengths. Following that, the current and future applications of solar energy is discussed briefly. In the first half of this decade, in 2013, the transparent solar cell technology was invented by MIT professors and since then it is accepted as future’s most effective way of producing energy. Considering the fact that the application areas such as integration in the buildings, car windows, greenhouses and other electrical applicants that has a screen to cover with transparent luminescent solar concentrators (TLSC) is extremely crucial in term of world’s 2030 and 2050 energy targets. This includes 32% and 100% sustainable energy shares, respectively. This study further examines the comparison of solar cell technologies such as newly emerging Perovskite and Quantum Dots by providing annual developments in efficiency. The quantum dots are used in TLSC in order to reflect the incoming sun’s ultraviolet and infrared wavelengths to panel’s PV cell where the electricity is generated. This technology is to be implemented through the simulation phase of this work.
Referring to above explanation, this study is related to create a model island by using AutoCAD to demonstrate the city life in every aspect in terms of energy. There are 10 different structures with various window surfaces to be covered with TLSC in order to determine the electricity generation. The solar radiation that comes on vertical positioned panels must be identified to obtain possible electricity production. For that reason, MATLAB is utilized to find exact value of the vertical solar radiation. After obtaining the results, the manual calculations took place in order to approve that the numbers match.
Being such a promising technology, the future prospects as financial point of views is investigated by using the price dropdown of the monocrystalline solar cell from 1975 to 2020. The possible future prices per Watt are effectively calculated by utilizing the trend between these years for 2030 and 2050 energy targets of the European Union. By using this trend, the future price dropdown of transparent luminescent solar concentrators is projected and if the model project were to take place in 2030 and 2050, the plausible budget belonging these years can be found.
As a conclusion, world’s population is increasing day by day as the energy demand. Therefore, instead of constructing new renewable technologies in land areas that are limited, using TLSC on buildings and other implementation fields would result in compensating the rising electricity demand.
Integrating renewable energies into a district heating network in a residential area in Dachau
(2021)
The project includes designing a low-temperature district heating network center with a flow and return temperature of 45 °C/20 °C in a modern residential area with 50 buildings with 37,000 square meters located in Dachau, Bavaria and consists two scenarios. In the first scenario, in energy generation, the focus was on the natural gas supply. And in the scenario 2 the region's renewable potential was integrated and replaced with fossil fuels. By comparing the two systems, although the investment costs of System 2 were more, it is more cost-effective in financial accounting, considering the government's financial support for renewable energy projects and more maintenance and fuel costs of the first system. According to the present factors and CO2 emissions, the renewable system was much better in environmentally-friendly terms.
This thesis presents an insight into the possibility of implementing the intelligent sector coupling between the heat and electricity supply grids by using the combination of a solar PV system, decentralized heat pumps and decentralized thermal energy storage in an existing district heating system with variable temperatures in Germany. The district heating system was optimized for the summer period utilizing the existing system’s Modelica language model in Dymola software. In order to implement the intelligent sector coupling between heat and generated renewable energy-based electricity a separate control theory was developed so that the generated electricity can be utilized in an efficient way to operate the decentralized heat pumps. Moreover, the role of decentralized thermal energy storage was also considered for the appropriate sizing of solar PV system so as to utilize the maximum amount of renewable energy-based electricity to produce heat during the summer period. The assessment of the energy production and utilization from different systems was carried out by performing the electrical and heat energy analysis of the simulation results.
The findings of the thesis exhibited an appropriately sized solar PV system which fulfilled up to the 80 % of total electricity consumption for heat production during the summer period by implementing an intelligent sector coupling between the heat and electricity supply grids.
With the increasing rate of urbanization in Africa, the need for sustainable building solutions have become more paramount. More so, the tropical weather condition in Africa, means that building requirement for cooling activities would equally increase. Thus, resulting in growing energy consumption in Buildings. Therefore, it is based on these concerns, that the proposed herbarium building in the Okavango Research Institutes (ORI), in Maun Botswana, seeks to examine environmentally sustainable solution for the proposed herbarium building. This research study, therefore, focuses on evaluating the environmental impact and energy saving potential from the use of commonly available construction materials used for façade units of a building using life cycle assessment methodologies. Thus, clay bricks and hollow concrete blocks were considered for analysis.
The life cycle assessment professional software tool, SimaPro 8.4.0 was used in performing a life cycle assessment of the considered building components (clay bricks, hollow concrete blocks, reinforce concrete, window units and PV system). Hence, using this assessment tool, environmental impact assessment on the considered building components was carried out, and the evaluation of the impact category using two environmental indicators, namely: global warming potential and cumulative energy demand, was performed.
Furthermore, a comparative study between the considered façade materials (clay brick and hollow concrete block) was performed in order to evaluate the contribution of the different façade unit to the ecological sink of the building system. Also, a comparative study between the façade unit and the other building components was performed to understand the significance of the façade unit in the overall ecological sink of the building. In addition, a CO2 mitigation potential from the use of a PV system for the supply of energy for cooling activities in the proposed herbarium was evaluated against the use of electricity for supply from the Botswana national grid.
Consequently, the results obtained showed that hollow concrete block offers a more environmentally friendly solution than clay bricks when used as façade unit in a building system. This because, it contributes twice as less GHG emission to the building ecological sink when compared with clay bricks. Although, clay bricks has a slightly better energy savings potential during the use-phase than hollow concrete block, the environmental impact associated with the production of clay bricks in form of embodied energy, outweighs the energy saving gained during the use-phase for a reference lifetime of 50 years when compared with hollow concrete block.
Also, the PV system’s CO2 mitigation potential when used for cooling activities during the reference lifetime of the building (50 years), resulted in a CO2 saving potential of 2.03E+06 CO2 Kg-eq. This finding showed that the PV system has a more significant impact on the reduction in the environmental impact of the building system than the environmental impact associated to the façade unit of the proposed herbarium building in Botswana.
Smart meter technology implementation in the last decade had initiated many data collection processes, which have provided a strong foundation for the development of Artificial Intelligence (AI) based load monitoring systems. It is easier to identify the energy-saving potential with the help of advanced load monitoring systems. Since 2015, deep-learning-based Nonintrusive load monitoring (NILM) is being focused in the research community. It requires minimal hardware, which can justify its development and maintenance cost. Several AI-based models and tools are available for load monitoring, but it is challenging to identify a suitable model for the specific application. There is still a domain-specific transformation, and considerations are usually required. The residential sector has been the focus area due to the market size, but the industrial sector still has massive potential for research and development.
Thus, in the presented thesis, dairy farms in Germany are targeted for developing a power disaggregation algorithm based on deep learning, which can identify the on/off state of individual appliances in the farm from the aggregated load profile data. Mainly four appliances named milk cooling (MK), milk pump (MP), vacuum pump (VP), and cleaning automatic machine (SA) are targeted for disaggregation. NILM is a promising approach to identify individual operating times of appliances. Thus, deep neural networkbased algorithms are developed, focusing mainly on one-dimensional convolution neural network (1D-CNN) and recurrent neural network (RNN).
Literature research was carried out to determine the state-of-the-art of deep-learningbased NILM and understand AI technology. Data acquisition for model development and testing was made from four dairy farms based out of Bavaria, Germany. The presented work provides a detailed discussion about data pre-processing and development of models. The result shows that deep-learning-based disaggregation algorithms outperform for this application area, and the proposed model successfully identifies the states of individual appliances. The presented work provides a foundation for modifying the proposed algorithm or developing a new algorithm for real-time power disaggregation.