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A cellular approach to optimize the integration of renewable generation into distribution networks
(2022)
The steady growth of the renewable-based technologies in the last twenty years has changed the character of the power systems significantly. Until today, there are more than 112 GW installed photovoltaic and wind parks in Germany and around 90% of the installed renewable generators are integrated into distribution networks. As a result, distribution networks are often facing congestion problems and more investments are needed for the required network development plans.
The political decisions in Germany for increasing the share of renewables in electricity consumption up to 65% until 2030 and the nuclear phase out until 2022 and further shutdowns of the coal power plants raised serious concerns about the reliability of power supply and feasibility of the transition plan.
The present dissertation has a look over the recent developments and offers a methodology for reduction of the resulted costs from further integration of renewable generators into the distribution networks. The suggested methodology is based on a cellular approach and helps also to postpone the unnecessary costly network expansions. Furthermore, it helps to integrate the renewable generators in an optimized way which has an added value to move towards the defined sustainability goals.
The proposed methodology has two steps. The first step is made up of the cellular approach and grey wolf optimization in MATLAB environment. In this step, the optimal combination of technologies for fulfillment of the defined goals are found out. The second step consists of the quasi dynamic simulations in PowerFactory environment. In this step, the suggested results from MATLAB optimization are investigated in semi-real situations. With the quasidynamic simulations, it is checked whether the results are tolerable from the point of view of network operation and whether it is possible to facilitate the network operation with certain strategies.
Malawi is a Least Developed Country located in Southern Africa to the East of Zambia. Malawi has a low electrification rate of 9%. Furthermore, unreliable and inadequate power supply are estimated to reduce Malawi’s GDP by 7%-9%. These energy sector challenges diminish the country’s prospects for sustained growth, poverty reduction, and improved delivery of health and education services. Various studies have been undertaken to determine how Malawi can improve it's energy sector through the deployment of renewable energy. However, these studies have not specifically examined how climate change related financing mechanisms such as the Clean Development Mechanism (CDM) could be utilised to mobilise financing and capacity development for renewable energy deployment in the country. This is despite the assertion that developed countries are committed to jointly mobilising US$100 billion per year by 2020 to support climate change mitigation and adaptation activities such as renewable energy deployment in developing countries. Through the use of questionnaires, case study analyses, policy reviews, academic literature reviews and interviews, this research sought to determine Malawi’s regulatory and institutional challenges and prospects for enhancing renewable energy deployment through climate finance instruments.
Among some of the research findings was that Malawi has relied on external support in order to develop capacity in the field of climate finance, hence in the absence of external assistance there are limited opportunities to incentivise various stakeholders to implement projects and to enhance awareness about climate finance. The study also discovered that Malawi’s climate finance determinants resemble a non-market seeking Foreign Direct Investment profile, hence the presence of opportunities for cheap and abundant emission reductions could improve climate finance investment patterns rather than the opportunities for emission reductions and co-products such as electricity through renewable energy technologies. The study therefore recommended that Malawi should create a renewable energy and climate finance promotion agency to assist with soliciting funding for renewable energy projects from concessional and non-concessional sources and drafting and implementing renewable energy policies. Another recommendation was that the country must create a Renewable Energy Fund to reduce the funding constraints that the media, project implementers and financiers have in undertaking various roles related to enhancing renewable energy deployment. Lastly, the study concluded that Malawi’s prospects for accessing various forms of climate finance and deploying climate finance projects can be improved through improvements in Malawi’s renewable energy and climate change institutional framework, and the modifications of climate finance instruments and methodologies to encourage flexibility and reduce institutional constraints.
In der Dissertation werden neue Potentiale und Anforderungen sowie neue Verfahren und Methoden zur Bereitstellung von Systemdienstleistungen erarbeitet. Der Fokus wird dabei auf das Wirkleistungsmanagement im Verteilnetz gelegt. Bei einer zunehmenden Durchdringung von Erneuerbaren Energien steigt der gegenseitige Einfluss mit den technischen Systemen im Netzbetrieb und bestehenden sowie zukünftigen Märkten. In der Arbeit werden organisatorische und technische Lösungen entwickelt, welche eine sichere Bereitstellung von Regelleistung sowie eine Unterstützung durch den Verteilnetzbetreiber für ein systemdienliches Engpassmanagement des Übertragungsnetzbetreibers ermöglichen.
Anhand eines 110-kV-Modellnetzes werden die technischen Lösungen aufgezeigt und bewertet. Dabei zeigt sich, dass eine erweiterte Betriebsplanung im Verteilnetz notwendig wird. Mögliche Konflikte können im Vorfeld durch eine Netzzustandsbewertung und Informationsübermittlung gelöst werden. Weiterhin können Anforderungen des ÜNB zur Unterstützung zum Redispatch im Rahmen einer Vortagesplanung integriert werden. Zur Realisierung der Prozesse und somit Erfüllung der neuen Anforderungen sind zum Teil technische Ände-rungen in den Systemen der Netzführung sowie organisatorische und rechtliche Anpassungen in der Handhabung des Engpassmanagements notwendig. Hierzu werden in der vorliegenden Arbeit konkrete Empfehlungen ausgesprochen.
In dieser Arbeit konnte gezeigt werden, dass eine direkte Methanisierung von CO₂, die über die Sabatier-Gleichung, CO₂ + 4H₂ ↔ CH₄ + 2H₂O, beschrieben wird, im Labor- und im Technikums-Maßstab unter Variation verschiedenster Bedingungen realisierbar ist. Die Sabatier-Reaktion findet beschleunigt unter dem Einsatz von Katalysatoren statt. Unterschiedliche kommerzielle Katalysatoren auf Nickel und Ruthenium-Basis konnten auf ihrer Eignung für die Methanisierung untersucht werden und mit im Labor präparierte Katalysatoren verglichen werden. Relevante Größen zur Beschreibung der Aktivität der Katalysatoren ist der Umsatz an CO₂, die Ausbeute an CH₄ und die Selektivität bezüglich der Sabatier-Reaktion. Im Labor wurden Umsätze und Ausbeuten von über 90% und Selektivitäten von nahezu 100% gemessen. Durch eine Änderung der Temperatur, der Eingangsmenge an Gasen, der Katalysatormenge und des Druckes können die optimalen Prozessbedingungen für die Reaktion spezifiziert werden. Eine weitere Betrachtung galt der Messung mit synthetischen und realen Abgasen (Oxyfuel, CCS) und darauf bezogen, der Einfluss einer Verdünnung des CO₂ durch Stickstoff und Sauerstoff und der Rolle von bekannten Katalysatorgiften wie Schwefel- oder Stickoxiden. Es konnte ein Zusammenhang zwischen der Stärke der Verunreinigung an Schwefel, der Reaktortemperatur und der Abnahme der katalytischen Aktivität ermittelt werden. Die Produktion von Kohlenmonoxid gibt zusätzlich Aufschluss über stattfinden Teil-und Nebenreaktionen.
Ergebnisse in der Laboranlage konnten zum Teil für den Aufbau einer Technikumsanlage, welche eine Vergrößerung zum Labor um den Faktor 5000 darstellt, genutzt werden. Eine Zahl von Experimenten wurde im Technikum wiederholt. Die Technikumsanlage ist dabei in der Lage ca. 250 kg CO₂ pro Tag aus CO₂-haltigen Abgasen in Methan umzuwandeln. Ein erweiterter Praxisbezug stellte die Einbindung des Technikums in einem Kraftwerk dar und die Messung mit realem Rauchgas. Ohne zusätzliche Reinigungsschritte des Abgases konnten auch hier Umsätze von 90% erreicht werden. Eine komplexe Temperaturentwicklung und Erhöhung auf 600°C im Reaktor wurde aufgezeichnet und führt dabei zur Abnahme des Umsatzes auf ca. 60%. Bei diesen Temperaturen stellt sich ein Gleichgewicht zwischen, durch die exotherme Reaktion, erzeugter und abgeführter Wärme ein. Als Reaktionsprodukt wird ein Schwachgas erhalten, welches für die Rückverstromung eingesetzt werden kann.
In der Methanisierung von CO₂ besteht die Möglichkeit das CO₂ in einen Kreislauf (Power-to-Gas) zu binden und so die Emission von Treibhausgasen zu mindern. Das erzeugte Methan fungiert als chemischer Energiespeicher und trägt zur Stabilisierung des Stromnetzes bei.
Energy demand of continents, countries, communities and individuals will continue to increase in the phase of increasing population and improvement in the living standards of people. The attempt to meet this ever increasing demand and at the same time protect the environment has resulted in the fast growth of power generation from renewable sources of energy especially from wind through wind power plants and solar through photovoltaic power plants. This growth has been facilitated by various support schemes such as feed-in-tariff scheme, feed-in-premium and quota scheme. Further growth is expected in the future. This is because of the existing support schemes and the expectation of the emergence of improved technologies for harvesting renewable energy.
This development of power generation from renewable sources of energy although positive lead to some distinctive negative effects on the existing electrical network to which they are connected. These negative effects are known and well documented. The fluctuating nature of wind and solar radiation at any given location over a given period of observation is seen to translate into the power they feed into the power network. This fluctuating infeed requires more active management of the network by system operators so as to ensure continuous reliable power generation and delivery. Sometimes the management process lead to non-utilization of power produced by the renewables sources. Secondly, expansion and reinforcement of some existing networks are needed in other to accommodate renewable power generators. These come at a cost. Many studies and researches have been dedicated to finding solutions to these issues.
This work agrees with the use of storage systems as means of solving these issues but the question that remains unanswered is what the optimal way is. There is also a further push given to the view of installing renewable energy plants together with storage systems as a unit in this work. The main task presented in this work, however, is a concept of sizing renewable energy plant and storage systems as a unit. The resulting renewable energy plant-storage unit has the objective of supporting the electrical network to which it will be connected. Firstly the support should be by reducing the fluctuating effect from renewable production. Secondly by helping improve the load hosting capacity of the electrical network. This will be by supplying the part of the load demand leading to the reduction of the overall power drawn by connected loads from the electrical power network.
Historic data of renewable resource and also the load demand at the point or bus of connection are the drivers of this concept. With the earlier mentioned objectives and random or stochastic nature of data involved, particle swarm optimization method is employed in implementing the concept of sizing to arrive at an optimal solution of required sizes of the renewable energy plant-storage system.
The concept of sizing is based on proposing an ideal load demand that can be supplied by a utility under normal operating condition at all time. It follows that any extra demand should be supplied by the optimally sized renewable energy plant-storage unit. In this work sizing results of three scenarios presented. A single node network with three different types of the load was used in testing the effect of optimally sized renewable energy plant-storage system on an electrical network. The outcome of this test showed that the optimally sized renewable energy storage-system improved the ability of the test electrical network to support additional load hence load hosting capacity of test network was improved. The process required modelling and simulation all of which were carried out using MATLAB Simulink software.
The German government has set ambitious targets for wind energy expansion and has implemented policy schemes aimed at facilitating market deployment of wind-generated electricity. Data on German wind energy market has shown that, wind energy generating capacity is increasing correspondingly towards the targeted values. Germany is the largest wind energy market in the EU (wind energy accounting for about 10% of the total electricity consumption in Germany) with an installed capacity of about 38.2 GW onshore by the close of 2014. The success of these policies has prompted other countries globally to adopt similar support schemes for renewable energies. However, the rapid growth of wind energy generation in Germany equally faces numerous challenges. Some of these problems are inherent to the wind energy technology while others are caused by the very policies instruments used to support wind energy expansion, such as limited availability of designated areas for wind energy development, non-uniform regulations, and rising prices. The objective of this research, therefore, is to assess the impact of the German energy and environmental policies on onshore wind energy development and to explore implementation options of the German model in Cameroon.
This research has examined the German onshore wind energy sector from a policy perspective based on existing literature, semi-structured interviews with major stakeholders, a case study of Brandenburg and a survey, with the aim of investigating the acceptance of wind energy and challenges the developers are facing.
Based on the study results, it can be affirmed that the future growth of the German onshore market will come from flexible government policies, which may offer fewer incentives to investors. Indeed, the cost of electricity from renewable energy technologies in Germany is in some cases already below retail rates. There is the need, therefore, to pursue strategic programmes that enhances market integration of wind energy. Furthermore, the study results equally shows that the German feed-in tariff based support scheme in its current form, cannot be implemented in Cameroon. This is because, the purchasing power of the Cameroonian population and the economic constraints of the government, makes it difficult or even impossible to adopt the current EEG model in Cameroon where often, basic needs are subsidized.
The article develops an analytical framework to explain the successes and failures of local community energy projects in the countryside. Theoretical elements based on ownership, technology acceptance, value chains and public opinions are developed and synthesised in two concepts: ´technical complexity and its antagonist social complexity. The achievement of a mature community energy regime is explained as a continuous process of consecutive single steps in both social and technical arenas.
Die “Energiewende” wird in der vorliegenden Arbeit als umfassender gesellschaftlicher Prozess aus soziologischer Perspektive untersucht. Da die Vorreiter der Entwicklung bisher in geographischen und damit auch sozialen Nischen zu finden sind, wurden sieben möglichst weit fortgeschrittene und ambitionierte „Energieregionen“ im ländlichen Raum als Fallstudien ausgewählt. Das Paradigma der Energieautarkie oder der 100% Region wurde dabei als Leitbild eines noch jungen Entwicklungspfades mit Hilfe qualitativer Methoden untersucht. Unter Energieautarkie (oder Energieautonomie) wird das Ziel verstanden, eine Region vollständig durch erneuerbare Energieproduktion mit Wärme und Elektrizität zu versorgen. Dies ist aufgrund der hohen Anforderungen bisher selten vollständig realisiert worden. Die vorliegende Arbeit beschreibt die Hindernisse, Entwicklungsstufen und typischen Probleme sowie die Faktoren, welche ihre Bewältigung ermöglichen. Im Vergleich der Fallstudien wird ein theoretisches Modell entwickelt, um den Erfolg einzelner Initiativen erklären und in gewissem Umfang vorhersagen zu können. Daraus wird die These abgeleitet, dass sich die technische und ökonomische Infrastruktur erneuerbarer „Energieregionen“ langfristig der Sozialstruktur anpasst und die Diffusion weiterer „Energieregionen“ vom gegebenen Niveau des Sozialkapitals bedingt wird. Aufgrund der gegenseitigen Abhängigkeit sozialer und technischer Komplexitätsniveaus bedeutet die Energiewende für den ländlichen Raum in erster Linie eine soziale und organisatorische Herausforderung. Die vorliegende Arbeit beschreibt die verschiedenen Strategien der beteiligten Akteure und ihre Konstellationen.
Cameroon has vast renewable energy resource potentials, with a hydropower potential of about 55,200MW, second only to the Democratic Republic of Congo in Africa. So far, its energy needs are met by 4.8% hydropower (which accounts for less than 5% of its total hydropower potential), 0% wind and 0% solar. Cameroons’ energy sector still goes through insufficient electrical energy production, especially during the heart of the dry season, which runs from December through March. Coincidentally, the wind and solar power potentials for Cameroon are at their peak during these months and could conveniently supplement for the shortfalls in generation during these periods. In this research, technical analysis were carried out to determine the wind and solar energy resource potentials for Cameroon using the RETScreen software tool provided by CANMET Canada. These analysis revealed that the northern regions of Cameroon had higher wind and solar resource potentials than any other location in Cameroon. A 2MW installed wind energy capacity would be capable of generating well over 1.5GWh electrical energy per year, while a 2KW installed solar energy capacity will be capable of generating well over 3MWh electrical energy per year. In the final sections, financial analysis were carried out to determine the economic viability of such projects and the possibility for self-financing. Emission analyses were also done based on the ability for such projects to offset greenhouse gas emissions and ensure sustainability in the energy sector. The analysis for Maroua revealed that 78.6tCO2/yr for wind and 0.1tCO2/yr for solar could be reduced by those installations. Finally, the legislations and legal frameworks governing the energy sector in Cameroon were dissected to determine possible weaknesses and constraints limiting the use, promotion and development of the full potential of Cameroon’s renewable energy resources.