The pressing need to mitigate global warming and transition to sustainable energy solutions has accelerated the development of innovative energy systems. This thesis investigates the sizing and design of a photovoltaic thermal (PVT) system integrated with aquifer thermal energy storage (ATES) within a fifth-generation district heating network (5GDHN) for a case study in the Werfgebied district in Hilversum, Netherlands. The study focuses on the configuration, storage distribution, and optimisation of component sizing within the district heating network to minimise overall electrical power usage, thus reducing grid dependency and CO2 emissions. A Python model of the multi-energy carrier system is developed, embedding the physical principles underlying the thermal and electrical properties of the components. The research finds that an optimal configuration for the ATES and PVT combination involves a single ATES well rather than distributed thermal energy storage. The results indicate that the size of the aquifer significantly affects the overall operating temperature and its fluctuations. A larger ATES maintains a stable but relatively colder temperature. Optimal sizing is achieved at the maximum allowed operating temperatures of an ATES in these areas, resulting in the most favorable temperature for maximum COP in the heat pumps. This minimises grid exchange and CO2 emissions. The optimal ATES size is determined to be 380,000 m3, in combination with 800 PVT modules, leading to a total CO2 equivalent emission of 856 tonnes.

The rapid adoption of electric vehicles (EVs) poses significant challenges to low-voltage distribution grids, particularly in regions with high penetration rates like the Netherlands. As EVs increasingly draw power from and feed power back into the grid through technologies such as Vehicle-to-Grid (V2G) and mobile V2G, the stability and reliability of low-voltage grids are put to the test. This thesis investigates how uncoordinated charging behaviors, combined with real-world factors like commuting patterns, impact grid performance. The study focuses on key technical aspects such as grid congestion, voltage fluctuations, and transformer loading, aiming to understand the potential stress points in the grid.

Through a series of detailed simulations, the research explores different operational scenarios involving smart charging, V2G, and mobile V2G technologies. These simulations assess the grid’s response to varying levels of V2G penetration, seasonal demand shifts, and commuting behaviors, providing a realistic analysis of the challenges that low-voltage grids face. The study models suburban Dutch grids, emphasizing real-world conditions such as the asynchronous nature of charging and discharging patterns and how they can lead to localized imbalances.

This research reveals the complex interactions between EV integration and grid performance, emphasizing that user-driven charging behaviors and the growing penetration of V2G solutions can lead to significant grid instability without proper coordination. The findings highlight the necessity for advanced grid management strategies, infrastructure reinforcements, and innovative charging solutions to mitigate these risks. By offering insights into the technical challenges of grid integration under various real-world conditions, this thesis contributes to a deeper understanding of the infrastructure requirements and operational strategies needed to support the transition to electrified transportation on a large scale.

This thesis titled "Addressing voltage sag contribution of an optimally sized Industrial Hybrid Power System" introduces a framework for sizing an industrial Hybrid Power System (HPS) to minimise Cost and CO2 emissions relative to connecting the industrial site directly to the grid with the help of a genetic algorithm, specifically NSGA-II. The framework utilises an Energy Management System (EMS) that is based on a rolling average principle which attempts to restrict the change in grid consumption from one time step to the next. The optimally sized configuration and its new grid consumption profile are analysed in the CIGRE MV Distribution Network to assess the effects of the new consumption profile on the bus voltages. The combination of a rolling average-based EMS and an optimal sizing with NSGA-II resulted in a $47\%$ reduction of the CO2 emissions while not worsening the voltage behaviour in the system (with a focus on voltage sag introduced by large loads).

As demand for clean and renewable energy around the world increases, solar photovoltaic (PV) technology becomes substantially popular, especially in low-voltage (LV) distribution networks. However, the integration of PV in LV distribution networks requires careful planning as it introduces voltage violations. To maintain network voltage, distributed control of residential-scale battery energy storage systems (BESS) is a possible option. Previous studies considered only one-day simulations with limited testing conditions. However, it is important to evaluate voltage control capability over an extended period of time. Moreover, it is important to estimate battery lifetime for the economic feasibility evaluation of distributed control.

This work aims to present a distributed control method for BESSs at a residential scale to provide voltage support in a highly PV-penetrated LV network while providing insights into their lifetime estimation. A control method based on a consensus algorithm with the addition of SOC balancing control is proposed and tested on a modified CIGRE LV distribution network using MATLAB/Simulink. Evaluations on the voltage support capability and control behavior are performed in various testing conditions and are extended beyond one day of simulation. Moreover, a battery lifetime estimation is performed using the resulting cycling profile from the proposed control.

The proposed control strategy can provide voltage support in most case variations with the exception of cold seasons and extreme addition of PV power generation. Concerning battery lifetime, there is only a small observable capacity fade from the proposed strategy’s cycling profile. It is important to investigate calendar aging because of the small cycling current from the operating conditions presented in this work.

The Netherlands is currently undergoing an energy transition in an effort to decarbonize its electrical grid and build a more sustainable generation model. This transition is being led by the integration of non-controllable, sustainable generation sources such as wind and photovoltaic (PV) power. The Dutch wholesale energy market has an imbalance settlement period in which the TSO penalizes or rewards deviations from the last submitted trading program (based on whether the deviations aggravate or relieve the overall market imbalance), and therefore, non-controllable sources are at a higher risks of suffering undesired deviations. The consequences of this are twofold: on one hand, they impose a strain on the grid and an increased demand of ancillary services; and on the other, they risk the economic profitability of the plant.
This issue can be bridged by combining non-controllable generation sources with storage assets.

Although the the dispatch of non-controllable energy sources has been studied extensively, there is a research gap in the proposal of revenue-maximizing strategies for operating hybrid power plants (with wind and PV generation, and energy storage capabilities) in the Dutch wholesale energy market, that account for the stochastic nature of the weather resources and include financial contingency factors.
This thesis aims to bridge that gap by setting up an optimization-based dispatch, using Mixed Integer Linear Programming. The optimization was extended to a scenario-based stochastic optimization, and the Conditional Value at Risk was introduced to account for the intrinsic financial risk of the dispatch under random weather conditions. The resulting problem is a two-stage optimization which was solved using a modified Bender's cut. The intra-day optimizations were also adapted as rolling-horizon dispatches, permitting the operation with periodic updates to the weather forecasts.


The study case for this research was the SWITCH lab, a small-scale laboratory developed by TNO to conduct empirical research on the integration of renewable energies and storage into the grid. TNO also provided the basis for a non-optimized dispatch strategy based on price benchmarking, which was used to compare the performance of the optimized strategy.

The optimized dispatch proved to be an effective strategy for producing maximal-revenue trading programs on all market closings. The optimized revenue provided revenues between 85.8% and 260.1% higher than a generation-alone plant configuration; and an increase in revenue with respect to a generation-only baseline between 300.0% and 8962.9% compared to the non-optimized strategy. Operation under a hybrid configuration using the optmized dispatch also yielded the best economic outlook, having the highest 10-year Net Present Value projections, an average Internal Return on Investment 57.2% higher than the hybrid plant under a non-optimized scheme and a 47.5% lower payback time.

The optimized strategy provided the most profitable trading programs for both the case of deficit and surplus of generation at delivery, turning a positive revenue even under unfavourable market conditions. Conversely, the non-optimized dispatch had the lowest economic outlook of any configuration, with worse NPV, IRR, and payback times than the generation-only plant.

These results highlight the importance of developing dispatch strategies that consider the long-term behaviour of generation and prices, as opposed to here-and-now strategies whose performance was shown to be comparatively deficient; and the synergy between storage and renewable generation sources to bridge the non-controllability problem.

This thesis focuses on analysing, troubleshooting and testing a USB-C to AC Inverter with USB-C power delivery, as well as implementing control- and protection systems for the flyback converter and implementing the H-Bridge switching control. The starting point of this project is a design that has already been manufactured as a PCB by DC Opportunities. A description of the existing design will be given, complemented with the implementation of the control and protection systems. Furthermore, an overview of the testing process will be portrayed and the results will be presented and interpreted. The USB-C input will use the power delivery protocol and a Flyback converter to get to 400V DC, followed by a full-bridge inverter for a 230Vrms AC output.

The inverter is part of a rural electrification project in which the goal is to provide electricity to people in rural, unelectrified areas. Initially, electricity is to be provided in the form of a charging station at a central kiosk or shop where appliances such as phones can be charged. Gradually, people can climb up the electrification ladder by purchasing power banks that can be charged at the charging station to provide the user with electricity in their home. Eventually, people will move further up the electrification ladder all the way to local generation via solar panels with battery storage at home. When enough people have local generation, a DC micro-grid can be constructed. The USB-C to AC inverter is there to give people the possibility to use AC powered appliances while the number of available DC powered appliances is limited. This gives people more options, while still keeping the advantages of a DC power system

The rapidly growing number of renewable energy technologies has started changing the infrastructure of the conventional energy sector, which was based on one-directional power flow. Bidirectional flows are created in the network with the integration of renewable technologies. The electricity network and system operators face many new challenges created due to renewable energy sources. Renewable energy sources are characterized by an intermittent and stochastic character which affects the power production from renewable energy technologies. Thus, the produced energy may pose challenges to the grid when it is higher than demand since the excess power is injected into the grid and it causes overvoltage problems.
BESS can contribute in facing the problems created by renewable energy technologies. They offer environmental benefits, they contribute to the integration of renewable technologies and they enhance grid’s reliability. These factors have as a result an increase in the integration of batteries in the electricity network. This research has as a goal to develop a control and coordination method for multiple BESS in a low voltage distribution network in order to address overvoltage and undervoltage issues caused by high penetration of PV units. There are many control strategies used in order to control the increasing number of batteries so that normal operation of the energy system is sustained. The main control strategies are centralized control, decentralized control and distributed control.
In this thesis study, a coordination control strategy of multiple BESS was developed to address the network's voltage violation issues caused by the high penetration of PV units. The coordination control strategy is based on a consensus algorithm that determines each battery's contribution to the network. The goal of this control strategy is to maintain the voltage within the limits. When a battery is not available due to a state of charge limit violation or maintenance, the amount of power that this battery would contribute under normal operation is distributed equally from the neighboring batteries until the battery becomes available again. This control strategy is a combination of distributed control, as it entails communication between neighboring batteries which share information together, and local control. The developed coordination control strategy is compared to a decentralized control strategy, which is widely used in distribution networks in order to control the contribution of batteries. Moreover, one of the batteries is emulated in the laboratory in order to examine the behavior and contribution of the battery, with the coordination control strategy implemented, in real-time application in comparison to the simulation.
The findings of this thesis study contribute to the research of mitigating voltage limit violations caused by renewable energy technologies by demonstrating the effectiveness and benefits of the proposed control and by providing a comparison of the proposed control to a decentralized control strategy, commonly used in distribution networks for controlling the contribution of BESS, for voltage regulation. Furthermore, the laboratory results contribute in the potential implementation of the proposed control in real distribution networks.

In rural areas, a stable electricity supply is in 2022 still not a certainty. To provide these areas with constant power, components to create a DC micro-grid are developed. This paper discusses the possibilities to create insight into the performance, the power which is drawn, and the productivity of the components. These parameters are fundamental for the users, operators, and developers. For offline data logging, the software is written for a micro-controller to log relevant data to a microSD card. The microcontroller is programmed in C, and the communication between the controller and the micro-SD card will be taken care of by the SPI protocol. The control of the file system is realized with FatFS, saving comma separate value files (.csv) containing all the desired data. For real-time insight and easy control of the device, an app framework is developed. This framework makes use of MQTT, Flutter, and Dart, to create a user-friendly and structured environment. The bi-directional communication between the app and the controller is done with the use of a wifi module, which communicates with the microcontroller via UART. The paper stands out with the integration of multiple controllers, program languages, communication protocols, and physical components.

To enable affordable and environmentally friendly eletrical energy storage, a battery was designed using sea-water as electrolyte. The performance of this battery was tested through repeated cycling under a variety of circumstances. The Coulombic and energetic efficiency were around 80% and 68% respectively. The battery saw a strong drop in performance after ~60 cycles. This was corroborated with results gained from four separate cells. Efforts to model the battery were limited by the accuracy of the utilized model itself.

The construction of reinforcements of the electricity grid cannot keep up with the increasing demand for transport capacity caused by the energy transition. This leads to increasing congestion of the grid. Therefore, the feasibility of battery energy storage systems as a solution is researched in this thesis. To make this a financially viable option, the free capacity of the battery energy storage systems is used to participate in the FCR and passive balancing market. Four (mixed integer) linear programming models are proposed to optimise the battery sizing and market participation. The feasibility of the solution is investigated through three case studies, which are based on three nodes of the distribution grid where structural congestion is expected. The study shows that for two of the three case studies a profitable business case can be theoretically accomplished.

The majority of Dutch homes currently use natural gas boilers to meet their space heating demand. Changes in this significantly large sector are required to achieve the sustainability goals established by the Paris Agreement. Since most renewable energy sources produce electricity, transitioning residential heating systems might cause problems managing national electricity grids. Furthermore, the intermittent nature of renewable energy sources leads to an imbalance between supply and demand.

These challenges can be overcome by combining different storage techniques. An example of such a technique is the thermal energy buffer developed by Borg, which focuses on single-household use. This thesis looks into the feasibility of such a system by comparing different scenarios for residential heating systems.

Three scenarios were modelled using Simscape. In scenario I, a natural gas boiler provided all the heating demand of the house. In scenario II, the heating system consisted of Photovoltaic Thermal (PVT) panels and the thermal energy buffer. In scenario III, the house was heated by PVT panels, the thermal energy buffer, and a heat pump. In all scenarios, the same house was connected to the heating system.

In scenario II, the system sizes were 0, 1, 2, and 3 PVT panels, combined with buffer capacities of 0, 2, 4, and 6 m3. In scenario III, the system sizes were: 3 PVT panels with 6 m3 buffer capacity, 1 PVT panel with 4 m3 buffer capacity, and 3 PVT panels with 2 m3 buffer capacity.

The total yearly heat consumption of the modelled house was 5109 kWh. In scenario I, 378 kg of CO2 was emitted. In scenario II, CO\textsubscript{2} emissions were highly dependent on the sizing of the PVT system and the TESS and ranged from 20 to 405 kg, based on a heating demand of 9444 kWh.

Scenarios I and III maintained a comfortable temperature during the entire year. The heating system of scenario II was insufficient to heat the house throughout the year for all modelled system sizes; however, the scenario could be acceptable with larger PVT and TESS sizing. By comparing CO2 emissions and payback time, the optimal capacity of the thermal energy buffer was found to be 6 m3.

The uncertainty of the future gas price causes a challenge in comparing the cost of electrified heating systems to traditional heating systems. Additionally, it underlines the necessity of decarbonizing residential heating systems to secure comfortable, affordable housing.

Royal IHC is known for building large dredging vessels which collect soil from the seabed. The vessel needs to remain in position, called dynamic positioning, which is done by large thrusters. These are mostly electrically powered thus the total amount of required power can range up to 50 MWs. Royal IHC wants to investigate the possibility of a DC vessel where the synchronous generator’s AC voltage is rectified via a passive rectifier. The question is how stable this is and what influences the voltage stability.

The thesis focuses on building a model of a DC powered propulsion system that allows analysis of voltage stability of the vessel. The model is generalized and consists of two parallel diesel generator sets with a passive rectifier. These generators are connected to a common DC bus with constant power loads which represent the loads of the vessel. The model is built in Matlab Simulink using the specialized power system toolbox and is verified with an RScad simulation. A measurement-based analysis tool is developed utilizing prony analysis. This allows analyzing the results of the simulation model and data from the field. Both cases are tested, the tool allows to get insight into the stability of the vessel.

Currently, the main revenue streams for grid connected BESS stem from regulated energy markets, such as Day Ahead Market (DAM) and Primary Frequency Regulation (PFR). Furthermore, BESS have great potential in providing services to network operators, however a clear business case for such functionalities is still missing. Therefore, this research aims to evaluate the potential business case for BESS in Distribution Networks (DNs) by integrating market application and additional DSO services. The technical and economic feasibility of the solution is verified via a case study of an existing Photovoltaic - Fast Charging Station (PV-FCS). Three players are involved, namely PV-FCS station owner, DSO, and BESS owner. A mathematical deterministic optimization problem is formulated using mixed integer linear programming (MILP), so to integrate BESS operation in the DAM and FCR market, and the remunerated services are offered to the DSO. The study shows that a potential BESS implementation in DNs is economically and technically advantageous for all the players implicated in the case study. The BESS owner would have additional revenues, the DSO benefits from a reduced peak power and the possibility of defer network investments, and the PV-FCS owner from an overall 30% tariff reduction thanks to the peak shaving performed by the BESS.

The urgency of taking actions against climate crisis is unprecedented. The human-produced CO2 is the largest contributor to global warming, which drives the climate change. Many countries around the world have committed to net-zero greenhouse gas emissions in the next coming decades. Power-to-X (PtX) technologies in combination with carbon capture technologies might contribute to a carbon-neutral future, since they can convert electricity and captured carbon to synthetic gases (e.g. hydrogen, methane), chemicals (e.g. propylene, ethylene) and liquids (e.g. methanol).

This thesis aims to research the techno-economic potential of a system that is able to produce methanol at industrial scale via a PtX scheme, which is coupled with carbon capture technologies. The system of this thesis consists mainly of PV panels, an alkaline water electrolyzer, a polymer electrolyte membrane (PEM) CO2 electrolyzer and a single-stage Lurgi quasi-isothermal methanol reactor. The feedstocks for this system are water and carbon dioxide (captured from the flue gases of a cement plant).

The whole production process of this system has been designed and modelled in such a way, that both electrolyzers can follow the intermittent power supply from the PV panels. The electrolyzer's dynamic operation is controlled by a deterministic control logic, which takes into account the variable energy efficiencies of the electrolyzers and the intermittent power output of the PVs. Moreover, it has been decided that the methanol synthesis is based on the CO2 hydrogenation process, which converts syngas (i.e. a mixture of CO, CO2 and H2) into methanol with the use of the methanol reactor. Hydrogen is produced by the water electrolyzer and the captured CO2 is reduced to CO by the CO2 electrolyzer.

As far as the sizing and production results are concerned, the system is able to produce 3.999 kT of methanol per year, consuming 2,147 tons of CO2 per year and requiring an energy input of 30.3 GWh/year. The installed peak PV power is equal to 18 MWp and 99.60% of their energy yield is exploited by the system (the rest is dumped). Due to the implemented control logic, the operating energy efficiency range for the CO2 electrolyzer is 45.07-55.32% and for the H2O electrolyzer is 75.83-81.71%.

In terms of economic analysis, the proposed system requires a total capital investment (TCI) of 195.7 M€ and its operational expenditures are equal to almost 2 M€ per year. The performed cash flow analysis showed that the system has an annual gross profit of € 855,535 per year. Despite the yearly profit, it was found that the system's net present value (NPV) is negative and equal to -179.5 M€ at the end of its lifetime (i.e. 20 years). Also, the levelized cost of methanol (LCOM) was found to be equal to 4.44 €/kg, which is almost 10 times higher than the current market price of methanol. Therefore, such an investment would be economically unfeasible, despite its environmental benefit, because it would result in a net loss of capital.

The company Ocean Grazer BV is interested in launching to the market a novel storage technology: the Ocean Battery. Such battery will be installed under the sea with the purpose to store the surplus power produced by wind turbines in the form of potential energy by filling an elastic bladder, exposed to the ocean pressure, with water. This thesis has two purposes: the first is to create in Simulink a model that can simulate the dynamic behavior of the hydraulic and electric components used for the filling and draining process of the bladder. The second, is to study how the engagement and dispatch protocol of the Battery Management System, applied to different configurations of the electric components, changes the efficiency and the performance of the system. Ultimately, the optimal configuration and protocol are evaluated and decided.
By “Machine Engagement and Dispatch protocol” we define the procedure adopted to determine how many, which and how the units forming the different stacks should be activated and operated given a certain power demand value. The protocols created will indeed communicate the system how many and which machines should operate in full load conditions and how much power the ones operated in partial load should exchange at any instant of time. The study solves the problems of the company which now has a dynamic model able to simulate the behavior of the power exchanging parts of the Ocean Battery and knows what the strengths and the weaknesses of the different configurations and protocols are. An optimal solution for the considered case has been found. Nevertheless, this study does not include the possibility of having more storage units communicating among them which remains an unsolved problem for the company. This further work could possibly be implemented starting from this thesis and using the created Simulink program, which is a new useful tool the company now possesses to progress in its growth.

This research aims to provide a method for large-scale commercial electricity consumers to procure towards 100% hourly matched renewable electricity. A problem with the current electricity balancing system is that the energy produced by Variable Renewable Energy sources (VRES), such as wind and solar PV, has a weather-dependent production profile and is thus non-controllable and intermittent. The balance between the total energy demand of the large-scale electricity (LSE) consumer and the production of electricity from VRES in their contract is only based on a yearly scale and not on an hourly scale. At moments when there is little wind, mainly coal & gas- powered plants need to be dispatched to secure uninterrupted power supply. Procurement of renewable energy is realized with the use of Guarantees of origin (GOs). GOs are an instrument that tracks the origin of electricity generated from renewable resources on a yearly basis but does not differentiate in hourly production profile. Therefore, this system will not be able to address the challenge of balancing VRES and demand on an hourly scale. In the future, with the ambition of moving towards substantially higher proportion of RES, the balancing on hourly base is needed to decrease the dependency on the conventional plants as backup. Therefore, with the current setup with yearly tracked RES, companies are limited in their role in the energy transition. This research aims to provide a novel method for large-scale commercial electricity consumers to procure towards 100% hourly matched renewable electricity. In this thesis, a techno-economic analysis was conducted to examine possible hourly-matched renewable energy portfolio for Dutch LSE consumers. First, an analysis was conducted of the production and storage technologies that could potentially be used for the application of hourly matching. Secondly, a methodology was developed to analyse the match between an LSE consumer’s demand and the production profile. The degree to which these profiles are matched was defined as the green score. The higher the green score, the higher the percentage of the demand that is covered by the portfolio on an hourly base. The demand profile is kept consistent, and a comparison is made of scenarios of different portfolios containing production and storage technologies. Third, using a Levelised Cost of Portfolio (LCOP) the cost per MWh for the whole portfolio is compared for different scenario’s. This study shows that the hourly match measured using the percentage green score can be significantly increased by adapting the LSE consumer portfolio, however a 100% hourly match is not shown. Much of the research to date has focused on national-scale scenarios, but only provides limited incentives and insights into the role that large companies can play. This study provides a tool which is suitable to perform a techno-economic analysis to increase the hourly match of LSE consumers using various electricity production and electrical energy storage technologies. The insights found on the impact of different combinations of technologies in a portfolio can be used to understand a further possible role of these companies in the energy transition.

With the increase in home energy consumption due to the electrification of house heating and charging of electric vehicles (EVs), the self-sufficiency and reduced impact on the utility grid from a house has become a more exciting topic. In combination with the price decrease for lithium-ion batteries the potential for storing PV generated energy in batteries has become more beneficial. However, the price for batteries is still a large part of the total investment of a PV system with home battery. Correct sizing of the home battery and PV installation is essential to reduce investment costs and as a result a decrease in payback time. Besides the correct sizing of the home battery and PV installation, these two parameters are also influenced when using an EV in the energy management system of the house. EVs have large batteries (thirty to hundred kWh) to give the EVs an extented driving range. The average EV owner does not use the full capacity of the battery on a regular day. The unused capacity of an EV battery has the potential to reduce the home battery capacity when used as a storage facility. To reduce the impact of the upcoming changes in house consumption, this thesis investigates load shifting in combination with a charged EV as addition to the house with integrated PV and battery. The results show that a charged EV can have a positive contribution to a house on grid energy autonomy, peak shaving capability and electricity cost. In combination with load shifting the benefits are further increased.