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How to measure flexibility
(2019)
Flexible power provision from biogas can significantly contribute to energy systems with high shares of renewables. However, the characteristics and demands for this flexibility are not clearly defined or measured. In this paper eight indicators are defined to shape “flexibility” and perform a downstream investigation of eight research projects focusing on flexible energy provision of biogas plants. The indicators are structured in three dimensions (1) velocity (ramps) by which the system can be modulated, (2) power range (bandwidth) and (3) duration for specific load conditions. Based on these indicators bottlenecks for the flexibility potential were identified. One crucial result shows that short-term flexibility of biogas plants is mainly driven by properties of the combined heat and power unit (velocity and bandwidth). The long-term flexibility depends mainly on gas storage, mode of operation and ability for modulation of the target gas production.
The potential of combining biogas and photovoltaic (PV) power plants in hybrid systems in the German distribution grid is analyzed. The focus of the present research is on balancing the intermittent power supply from PV power plants with the controllable power production of combined heat and power (CHP) units of biogas plants within a period of seconds. To achieve an increase of the total energy feed-in of biogas and PV power plants to the electricity grid, a biogas plant energy management system is described. System parameters, such as the variable feed-in of PV power plants or power ramps of the start-up process of controllable biogas plant CHP unit, are described and adapted to the global installed capacity of PV power plant and biogas plants in the German distribution grid.
More than half of the urban population of Sub-Saharan Africa lives in informal housing conditions. While urban areas are, in general, characterized by a high electrification rate, residents of informal settlements are still affected by energy poverty, the use of traditional energy sources and unreliable electricity supply. The aim of the study is to give an overview of different renewable-energybased solutions which are able to improve local energy provision. These are Solar Home Systems, Mini-Grids, and Energy-Hubs. The technologies are compared to another option for improving energy supply, namely Grid Expansion. The analysis is based on 24 Key Performance Indicators, which can be classified into technical, economic, environmental, social, and political dimensions. The selection of indicators is based on the challenges prevalent in informal settlements that impede a comprehensive, sustainable energy supply. The literature-based indices are used to determine which of the four technologies is a suitable solution for minimizing the challenges prevailing in informal settlements. The resulting matrix provides a holistic comparison and serves as a decision aid in selecting the appropriate technology for future projects in informal settlements, depending on local conditions and the needs of the population. The results show that the Energy-Hub is a valid alternative for energy supply improvement in Informal Settlements.
KomBio-Speicher
(2020)
Kyrgyzstan – a Central Asian country – faces a high degree of energy insecurity. Especially the Kyrgyz power sector suffers from outdated infrastructure and is not capable of fulfilling the growing and fluctuating inter-seasonal energy demand. On the contrary, the country is endowed with an abundant amount of renewable energies, which can significantly contribute to bringing stability to the energy sector. The current energy policy is considered as one of the key barriers to the developing the renewable energy sector in Kyrgyzstan. Hence, there is an immediate need to evaluate the formulated energy policy to investigate gaps and uncertainties. In response to that, the presented study is the first attempt that provides an in-depth assessment of Kyrgyzstan's current energy legislative framework. It determines the primary mechanisms for the operation and conduction of renewable energy sources in terms of legal and economic aspects. Furthermore, it provides detailed insight into the current Feed-in tariff calculation methodology and scrutinizes the special provisions for private investors. Based on the in-depth assessment, the article recapitulates the shortfall in the existing energy policies. The article found that there is huge potential available for the renewable energy market. To unlock that, the presented article emahsised on synergestic policy making approach to overcome barriers and expand the Kyrgyz renewable energy sector. The article further showcased how the improvements in the regulatory framework would raise the interest of the private investors / local energy players to promote the installation of renewable energy technologies over the county.
Insulating glass flat-plate collectors can save cost by being produced quickly and automatically in insulated glass production facilities, and they can be filled with argon to reduce heat loss. During its lifetime, the collector is likely to lose argon because of gradual material degradation of the sealing. However, information on the influence of the argon concentration on the collector efficiency is limited. Therefore, the objective of this research work was to analyse this effect. A theoretical material property calculation of argon-air mixtures was carried out to determine the convective losses with variable argon concentrations. Thermal collector performance was measured experimentally using an outdoor solar tracker test rig. The results strongly suggest, that the influence of argon concentration on both the convective losses and the thermal efficiency is non-linear. The measurements revealed that an argon concentration of 90 % can increase average thermal performance by 6.7 ± 4.8 percentage points. An increase in argon concentration from 0 % to 50 % has almost twice the effect on average thermal efficiency as an increase from 50 % to 90 %. Concluding from these results, an argon leakage threshold of 2.5 percentage points per year is proposed to avoid disproportionate loss of efficiency over time.
Methodological Evaluation of Storage Systems for Flexible Power Generation from Solid Biomass
(2018)
In rural Kyrgyzstan, the energy need is usually derived from multiple natural energy resources such as firewood, charcoal, agricultural residues, animal dung, and wood branches, which are considered common and predominant practices. Because of the non-sustainable resources and heavy reliance on the environment, Kyrgyzstan is one of the most vulnerable countries to climate change in Central Asia. On the contrary, the great renewable energy potential in Kyrgyzstan is untapped, which could be the most promising solution to ensuring sustainable energy supply in the country. However, because of the lack of scientific knowledge, current energy policies, and the lack of infrastructure, renewable resources are mainly untapped. To exploit the country’s renewable energy potential, there is a need for a systematic diagnosis to develop a strategy to explore renewables in Kyrgyzstan, which is currently missing in the existing literature. In that regard, the presented study aims to assess the current status of renewable energy sources by considering the local energy context from a potential point of view. Further to this, it provides a comparative overview through a matrix of strengths, weaknesses, opportunities, and threats. Such novel analysis would be the fundamental base for formulating policy advice and a national plan to enhance the utilization of renewable energy in Kyrgyzstan. The presented analysis was carried out based on the extensive literature review, the country’s national plan, and the existing energy policies of Kyrgyzstan. The article found out that there is huge potential available for the renewable energy market. As compared to other renewable energy sources, solar energy has great potential and can be considered one of the pioneer sustainable sources for integration into the country’s power generation framework.
Building construction in rural Kyrgyzstan is heavily dominated by earthen buildings. Old and inappropriate residential building structures contribute significantly to high domestic space heating energy consumption. Therefore, it is necessary to understand the relevant building construction techniques. However, the scant information on Kyrgyz building techniques, especially for high-altitude rural settlements, was the prime motivation to perform the presented study. The key objective of the study is to investigate residential building construction techniques in high-altitude rural Kyrgyzstan, and this was to be achieved by house visits during field trips, literature review, and pilot interviews with local people. The analysis enabled the detailed identification of individual building envelopes as well as predominant building materials to be recorded. Based on the assessment, a housing profile was created that represents the typical characteristics of traditional rural Kyrgyz houses. Furthermore, the study demonstrates the potential for energy savings in rural Kyrgyz houses of 50–70%. However, local conditions prevent people from making improvements to all domestic energy efficiency parameters simultaneously. Therefore, the study developed a ‘sequential roadmap’ to reduce domestic space heating demand in different phases based on simulation studies. Existing low-income rural Kyrgyz habitations can use the presented roadmap to reduce domestic space heating demand sequentially to overcome financial barriers and, therefore, contribute to establishing sustainable buildings in Kyrgyzstan. These results may be partially replicated in other Central Asian rural communities depending on their location and building characteristics.
Energy is a pivotal element for overall development. Therefore, affordable and clean energy for all (Sustainable Development Goal 7) is one of the important elements. Despite a suitable approach, Kyrgyzstan lags behind to achieve its Sustainable Development Goals by 2030. Improving access to energy can significantly impact the progress of many other sustainable development targets. However, access to reliable, sustainable, and adequate energy is a crucial task in rural Kyrgyzstan. Taking into consideration the energy situation and the importance of the availability of energy services, the overarching aim of the presented article is to map the potential of improving rural energy services to foster overall sustainable development goals. The article presents the most relevant information about rural energy usage behaviour based on three primary pillars: energy demand, energy carrier, and energy sources. In addition, the presented research article synthesises the key driving factors which have a direct or indirect impact on the energy services in rural areas. The summarised data displays a deep insight into a variety of complex and dynamic household energy consumption patterns. The article provides a potential solution nexus to foster improved energy services in rural Kyrgyzstan and therefore to foster the overall sustainable development in Kyrgyzstan. The findings of the article help to formulate a strategy to design rural energy services for policy makers and stockholders.
Die im Laufe des vorliegenden Vorhabens zusammengetragenen Informationen zeigen, dass der Blech-Rohr-Absorber als der momentane Stand der Technik verschiedenste Schwächen im technischen als auch wirtschaftlichen Bereich aufweist. Im technischen Bereich liegen diese sowohl im konstruktiven Aufbau aufgrund seiner vielen thermischen Widerstände, als auch in der momentanen Lösung der Verbindungstechnik. Die im Rahmen des Projekts durchgeführte Altkollektoranalyse zeigt, dass bereits früher verschiedenste Absorberbauformen auf dem Markt verfügbar waren. Diese Bauformen sind in der Fachliteratur teilweise dargestellt, jedoch kaum beschrieben oder näher untersucht. Die Analyse der großteils mehr als 20 Jahre alten Kollektoren ergibt, dass Bauformen und Absorbermaterialien bereits damals eine hohe Lebensdauer erreichen konnten. Defizite können nur bezüglich transparenten Abdeckungen, Zwischenschichten, Wärmedämmungen und bezüglich des hohen Absorber- bzw. Kollektorgewichtes ausgemacht werden. Thermographische Untersuchungen belegen, dass damalige volumetrische beziehungsweise teilvolumetrische Bauformen im Vergleich zu heutigen Konstruktionen gleichmäßigere Temperaturverteilungen aufweisen. Die Verbindungstechniken, speziell im Bereich der Blech-Rohr-Absorber, haben sich allerdings in Qualität und Stabilität im Vergleich zu damals verbessert. Hohe Stillstandstemperaturen aufgrund neuer Entwicklungen im Bereich Absorberbeschichtungen und optimierter Glas- und Dämmstoffe bringen jedoch auch die verbesserten Verbindungstechniken zwischen Blech und Rohr an ihre Grenzen. Schliffbilduntersuchungen, durchgeführt an verschiedenen heute im Absorberbau angewendeten Fertigungsverfahren, lassen fertigungs- als auch wärmetechnische Schwächen, wie z. B. inhomogene beziehungsweise spröde Nähte oder kleine Flächen für die Wärmeübertragung, erkennen. In der Konzeptphase werden nach Ausarbeitung einer Anforderungsliste und Untersuchung des Absorbers durch eine Funktionsanalyse verschiedene Lösungsprinzipien erarbeitet. Aus diesen erfolgt die Entwicklung von Absorberkonzepten in Form von Skizzen, die schwerpunktmäßig auf eine volumetrische Durchströmung des Absorbers abzielen. Im nächsten Schritt werden für die aussichtsreichsten Konzepte eingehende Untersuchungen aus technischer und wirtschaftlicher Sicht durchgeführt. Eine Berechnung hinsichtlich technischer Eigenschaften, wie Gewicht, Füllvolumen, Wärmekapazität und vor allem des Absorberwirkungsgradfaktors wird unter anderem durchgeführt. Weiterhin wird eine Voranalyse der Absorberkosten hinsichtlich Material- sowie Fertigungskosten erstellt. Basierend auf diesen Informationen können die Absorberkonzepte abschließend in einer Bewertungsmatrix bewertet werden. Es erfolgt dazu die Festlegung mehrerer differenzierbarer Bewertungskriterien, anhand dessen eine objektive und grundlegende Unterscheidung sowie Klassifizierung der Absorberkonzepte sowohl in technischer als auch wirtschaftlicher Sicht möglich ist. Diese Konzepte sind Ausgangsbasis für ein weiteres, folgendes Projekt, das zuerst auf eine grundlegende Ausarbeitung dieser Konzepte abzielt. Diese werden im nächsten Schritt mit Hilfe einer Simulationssoftware detailliert untersucht und hinsichtlich Wärmeübertragungseigenschaften sowie Druckverlust optimiert. Nach einer erneuten Bewertung ist eine Fertigung der favorisierten Konzepte in Form von Prototypen für praktische Vermessungen und Optimierungen in einem Sonnensimulator vorgesehen sowie die Implementierung in ein neu zu entwickelndes Kollektorgehäuse. Das vorliegende Vorhaben wurde von der Firma Thermo|Solar AG in Zusammenarbeit mit dem KOMPETENZZENTRUM SOLARTECHNIK an der Fachhochschule Ingolstadt durchgeführt. Die Förderung des Vorhabens erfolgte durch die Deutsche Bundesstiftung Umwelt unter dem Aktenzeichen 21543.
Mit der Verabschiedung des Erneuerbare Energien-Gesetzes (EEG) im Jahr 2000 und den Novellierungen in den Jahren 2004 und 2009 wurde die Voraussetzung für den wirtschaftlichen Betrieb von Biogasanlagen geschaffen.
Jedoch erfüllen nicht alle Biogasanlagen die Erwartungen einer nachhaltigen und klimaschonenden Energieerzeugung. Übereilt durchgeführte und damit unvollständige Planung und qualitativ fragwürdige Ausführung stellen die Hauptprobleme bei Biogasanlagen dar. Die Auswirkungen finden sich sowohl im ökonomischen als auch im ökologischen Bereich (Sonnleitner und Zörner 2008).
Im Rahmen des Projekts „Ökologische und ökonomische Optimierung von bestehenden und zukünftigen Biogasanlagen“ wurden je 10 typische Biogasanlagen in Bayern (BY) und Nordrhein-Westfalen (MS) intensiv untersucht.
In dieser Handreichung werden 10 konkrete, auf den Ergebnissen der Anlagenuntersuchungen basierende, technische, in die Praxis umsetzbare Lösungsansätze detailliert und verständlich für Planer, Hersteller und Anlagenbetreiber dargestellt. Die Konzepte zielen darauf ab, einerseits die Wirtschaftlichkeit von bestehenden und zukünftigen Biogasanlagen zu erhöhen und andererseits die Treibhausgasemissionen zu minimieren und damit die Ökologie von Biogasanlagen zu verbessern.