Renewable Energy Systems (M. Sc.)
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The global population is anticipated to experience a significant surge by 2050, posing profound challenges in ensuring food and energy security. Concurrently, the prevalence of hunger, exacerbated by pandemics, climate shocks, and conflicts, underscores the urgency to enhance agricultural productivity and energy efficiency. Agriculture currently accounts for 70% of freshwater consumption and 30% of global energy usage, requiring innovative solutions to meet increasing demands. In this context, Agri-Photovoltaic (Agri-PV) systems emerge as a promising approach, integrating agricultural practices with solar technology to enhance food production and energy generation simultaneously. These systems not only address the pressing need for sustainable food and energy sources but also offer benefits such as resilience against extreme weather events and income diversification for farmers.
This study investigates the potential of Agri-PV systems to address power outages in rural areas of Kissane in Morocco, as well as Bouda in Algeria. These areas are characterized by weak grid networks. After developing the load profiles of farms and households in the case study areas based on real data and literature, the PV-SOL software is utilized to estimate the size of the photovoltaic system. After simulation in the software and considering the type of Agri-PV substructure, three different scenarios for sizing the system are taken into account. The first scenario aims to cover all energy demands for both farms and households, the second focuses solely on farms, and the third focuses only on household energy requirements.
The results reveal that with six hours of power outage in a day, Kissane requires a 39 kWp Agri-PV system with an 85.31 kWh battery to fulfill its total energy demands. For farms alone, a 38 kWp system with an 82.04 kWh battery is necessary, while households, due to cooperative arrangements and few houses, need only a 1 kWp system with a 3.27 kWh battery. In Bouda, facing six power outages in a day, a 46 kWp system with a 144.34 kWh battery is required for total energy, 41 kWp with a 125.78 kWh battery for farms, and 5 kWp with an 18.56 kWh battery for households. Economic analysis favors Morocco due to higher electricity prices, yielding Kissane a positive 8.69% internal rate of return (IRR) and a competitive 10.95 cent/kWh levelized cost of electricity (LCOE). In contrast, Bouda faces economic challenges with a -2.93% IRR and a 13.77 cent/kWh LCOE, necessitating financial incentives for viability.
Keywords: Agri-Photovoltaic (Agri-PV), power outage, load profile, grid network, rural energy security, Morocco, Algeria
The dairy farms form a vital part of German agriculture and consume significant energy for their operation. Germany is working towards energy transition to transform the existing fossil fuel-nuclear system to a sustainable energy system that relies on renewable sources due to various societal and political demands. As the energy demand is increasing due to the rise in population, there is also a growing push in Germany to adopt energy efficient technologies and measures to reduce energy waste. There is a scope for improving the energy efficiency in dairy farms. Using energy optimization techniques can help reduce the load on energy suppliers as well as increase cost savings for farms.
German farmers are adopting newer digital technologies to achieve optimization of energy in their farms. One of the key tools in realizing energy optimization is the Energy Management System (EMS). The use of EMS in the case of dairy farms has been reviewed and presented in this work. The objective of the study is to investigate the potential of energy optimization in dairy farms. Efficiency measures like replacing inefficient farm equipment are necessary to achieve energy efficiency. These measures are discussed in detail and their potential to save energy in dairy farms is presented. A comparison of all these measures is studied and how much energy savings can be obtained is reviewed.
The use case scenario of EMS in different applications is presented as an indication of possibilities for energy savings using EMS. Furthermore, how the AI technology in combination with EMS can be used in farms and its benefits in dairy farming is reviewed. The types of farms on which the energy optimization measures can be implemented in an ideal case scenario are reviewed. The result of the study shows that there is vast potential for energy optimization in German dairy farms. Thus, the presented work can be further studied to identify further optimization possibilities with the advancement of AI and newer technologies.
Energy independence of commercial buildings is a critical aspect of modern construction. In the context of a planned office building project in Ekibastuz, Kazakhstan, located in an extreme climate with unstable coal energy tariffs, it is necessary to determine the energy needs and understand how to cover them. This thesis focuses on determining the level of efficiency in the use of electricity, reducing dependence on local energy suppliers, and integrating alternative sources. The energy assessment was carried out using software tools such as Autodesk Revit and DesignBuilder, which allow the integration of building information modeling (BIM), building energy modeling (BEM) and energy supply modeling (ESM) to optimize the energy design.
The results of commercial projects aimed at achieving nearly zero-energy building (nZEB) standards have informed the development of two energy concepts, both aiming to decrease dependency on district heating networks. These concepts encompass electrical and thermal concepts. In the electrical concept, the air-water heat pump (AWHP) and electric boiler demonstrated better energy efficiency compared to the thermal concept, which utilized a biomass boiler in conjunction with solar thermal collectors (STC) to mitigate the impact of coal-fired electricity. In addition to reducing energy dependence in the air handling unit (AHU), it is proposed to introduce a ground water-to-water heat pump (GWWHP), which is connected to the surface exchanger to capture heat leaks from central heating networks. A comparative analysis of installations without and with heating recovery unit (HRU) shows a fivefold reduction in electricity consumption for heating supply air. Solar technologies, including STC and photovoltaic (PV) panels, are integrated into each concept, but the limited use of STC makes a PV system the preferred option. The decisions made during the modeling process resulted in a fourfold reduction in the office building's average annual consumption compared to government requirements. Selection of energy efficient equipment and modeling led to nZEB classification for both concepts, achieving renewable energy system (RES) penetration rate from 16% to 33% of total consumption.
Economic analysis using the annuity method highlights the cost-effectiveness of rooftop PV systems compared to façade PV systems. In addition, wood pellets and solar heat help reduce costs in the thermal concept. The environmental analysis shows the significant reduction in carbon dioxide emissions achieved by the thermal concept, highlighting the importance of alternative energy sources for sustainable urban development.
The demand for heat energy is increasing worldwide and to achieve net zero
carbon emissions targets, more innovation is needed for heat production. Heat
pumps are considered a potential replacement for boilers and are currently in
high demand. The next approach is to optimize the use of heat pumps with
household PV production to avoid grid overloading due to running increased
demand by the heat pump. In this work, a Reinforcement Learning algorithm is
used in the MATLAB RL toolbox with an energy-building model built in MATLAB
Simulink Carnot. The energy building model uses a heat pump to charge thermal
storage, and a PV system is considered with a typical ON/OFF strategy. This work
shows how the RL toolbox has the potential to interact with this energy-building
model to optimize the heat pump with a PV system. All suggested agents by the
MATLAB RL toolbox are investigated with this building energy model (BEM), and
annual simulation is performed with a well-trained agent, which converges
during training. Two different models have been developed for heat pump
control. The first model is called the RL-based Heat Pump Controller, which is
designed to meet thermal targets only. The second model is called the PV-
optimized RL-based Heat Pump Controller, which not only meets thermal targets
but also considers the operation of the PV system with the heat pump. The
simulation results show that using the RL toolbox, the RL-based Heat Pump
Controller model has performed excellently. In the PV-optimized RL-based Heat
Pump Controller model, there is almost a 4.37% increase in PV self-consumption
compared to the typical control strategy, resulting in annual electricity savings
of almost 3.52 MWh. Some challenges of using the RL toolbox are also
highlighted with future recommendations, which mainly include computational
efforts.
This thesis is focused on investigating the different criteria, such as Wind Capacity Penetration, Wind Energy Penetration, Maximum Share of Wind Power, Short Circuit Ratio and Simultaneity Factor. The main idea is to determine these criteria application areas, particularly installed power limitations in a particular region, in terms of grid stability.
The passenger transport sector is undergoing a transition towards electric mobility to reduce CO2 emissions. One commonly mentioned challenge that could hinder the success of electric vehicles is the availability of public charging infrastructure.
This work focuses on optimizing public car infrastructure from both technical and economic perspectives, providing valuable insights for decision-makers and operators of charging infrastructure.
It begins with a general analysis of mobility behavior in Germany, followed by an examination of charging locations.
Subsequently, the stakeholders involved in public car charging infrastructure are identified, and their goals are used to construct a set of key performance indicators (KPIs). These KPIs enable a comprehensive assessment of public car charging infrastructure.
The identified KPIs, including Economic Efficiency, Utilization, and Usability, are then applied to an exemplary set of public charging points, showcasing the practicality of these metrics, and offering valuable insights into their current situation.
The findings from the application of the KPI set, such as the critical economic situation of the assessed public charging infrastructure, are integrated with potential improvement opportunities and concrete measures to achieve the set goals.
The work emphasizes the importance of charging demand and utilization rate as key factors for the success of the evaluated charging stations, while also highlighting various other aspects that can enhance the performance of any public charging station.
Power systems globally are undergoing a significant transformation driven by the need to transition from fossil fuel-based systems to low-carbon and renewable energy sources. Increasing distribution energy resources penetration has led to the development of local generation and consumption ideas and, consequently, the emergence of the microgrid concept. However, the displacement of traditional power plants by distributed energy resources, especially in low voltage grids, poses new challenges for distribution grids’ operation, such as voltage control. The reactive power support capability of distributed energy resources, one of the microgrid components, makes them a potentially useful source for voltage issues. However, this support should be allowed within the framework permitted by regulations.
Although the Brazilian power system is mainly based on renewable energy sources, Brazilian legislation does not support the potential service capability of distributed energy resources. Moreover, the absence of an ancillary services market and the non-remuneration of ancillary services are the main reasons for distributed energy resources and microgrids not participating in such services.
This thesis proposes developing two business models for a non-isolated microgrid in Brazil, one that considers regulations and one that can be described as innovative by not considering regulations. The business model has been developed with a reactive energy compensation approach in which PV inverters are used. Furthermore, two different remuneration mechanisms have been proposed for the innovative business model. The microgrid where the developed business models are implemented is modelled and simulated in Open Distribution System Simulator with IEEE 13-node test feeder. Since the simulated microgrid does not have any voltage issues, sensitivity analysis is performed to be able to provide more accurate results. The sensitivity analysis results show that the proposed remuneration mechanism can motivate the microgrid to provide ancillary services, resulting in a profit for the microgrid and mitigating voltage problems of the distribution grid.
The further expansion of decentralized renewable energy sources and ramp-up in electric mobility and heat pumps triggers the need for traditional grid reinforcement measures. To effectively address the growing demand, it is crucial to simultaneously assess numerous options to generate technically optimal and economically feasible solutions. Therefore, new traditional grid reinforcement measures are introduced to the grid planning tool, eDisGo, and grid reinforcement simulations are conducted on high-resolution synthetic grid models representing the German grids for the investigations. Firstly, one scenario representing the future state of the German grid and six synthetically generated medium voltage grids, including underlying low voltage grids, are chosen. After grid issues are determined by respecting voltage and loading limits with power flow analyses based on the selected scenario, the existing and new measures are applied to the grids as a group or individually to solve the issues. Subsequently, with the results obtained for the MV and LV grid levels, the changes in the grids are analysed, and the extent to which the employed measures provide improvements. Lastly, as a result of the analyses, considering the grid reinforcement costs of each measure or measure group, the optimal solution for each grid characteristic is presented. In grids with highly loaded long feeders and a high number of feeders, reinforcements for LV grids with an additional MV/LV substation can offer the most suitable solution in terms of cost and improvement ratings. Splitting the feeders at a particular point provides cost-efficient solutions in reinforcing critical voltage deviations in MV and LV grids. In the reinforcement of overloading issues, the most optimal solutions cost- and improvement-wise is generally adding-line-based measures if the feeders are not long and comprised of highly overloaded lines. Optimization of switching unit in medium voltage rings conducted based on the loading of the feeders; although it is not a suitable solution in every case in terms of cost and improvement, costs can be kept at a lower priority since it is a vital reinforcement measure in terms of ensuring supply reliability in the rings.
In response to the rising environmental concerns, emission-free ferries, particularly hybrid hydrogen fuel cell and electric battery (HFC-EB) ferries have been considered a promising alternative to conventional ones with the potential to achieve efficient emissions reduction. However, their widespread adoption in the maritime industry is still limited due to numerous obstacles, including the lack of the required infrastructure to support them and the absence of regulatory frameworks such as refueling protocols designed for ferries. Currently, the design of hybrid ferries’ storage systems is driven solely by their requirements and focuses only on the optimization of the ferry’s operational side using several approaches, such as energy management systems (EMS). In regards to this, the present work considers the infrastructure dimension, such that a proposal of a hydrogen refueling protocol for ferries has been first developed based on the SAE J2601 standard designed particularly for light-duty vehicles. Further to this, two simplified models of a hydrogen refueling station (HRS) and a power charging station (PCS) infrastructures have been developed in Dymola/Modelica and later used to conduct the optimization investigations of a selected ferry case study regarding the infrastructure in a holistic approach. The energy split design between hydrogen and electricity was studied along with other parameters that impact the infrastructure design to be optimized regarding the infrastructure holistically by running various simulations. The sensitivity analysis results of these investigations’ simulations show the significant impact of infrastructure consideration when designing a hybrid ferry. In addition, it has been demonstrated that immense potential benefits can be harvested from the infrastructure perspective in terms of efficiency and cost effectiveness, including savings of power losses, cooling energy, storage system volume on board the ferry, and operational costs of both the ferry and infrastructure. Finally, by considering all the findings in an integrated and interconnected way, stakeholders of the maritime transportation sector, including ferry owners and operators and infrastructure providers, can identify the optimum split design of the hybrid storage system in a holistic approach regarding the infrastructure following the methodology for optimization developed
throughout this work.
Keywords: Hydrogen fuel cell/electric battery ferry, hydrogen refueling protocol for ferries, storage system design, optimization methodology, infrastructure, charging, refueling, simulation
The main objective of the thesis is to develop the simulation model of the refrigerant cycle in full operation mode by MATLAB Simscape and validate the model with the measurement data from the existing heat pump prototype. It starts with introducing the fundamentals of heat pumps, including explaining the refrigerant cycle, coefficient of performance, and performance factor. Then review the application of different types of heat pumps, refrigerants, and heat exchangers from the literature. For modeling the heat pump, two methods are used in the work. The compressor and the expansion valve are using the first method which is modeled by the datasheet and the measurement data; the condenser and the evaporator are utilizing another method for modeling which is by the MATLAB tool parameter estimator. The thesis has explained the detailed method of modeling the heat pump. After completing the model, it has been run and validated by the measurement data from the prototype. The model can operate properly and the properties of the simulation model are reasonable. But for validating the model which means compared to the measurement data from the prototype, there are still some flaws or errors, especially for the evaporator model. They will be discussed in the work. Overall, the thesis still provides a promising method for developing the simulation model of a heat pump.