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The Educational Journal of Renewable Energy Short Reviews (EduJRESR, formally published as ‘EGU Journal of Renewable Energy Short Reviews’) is a teaching project rather than a regular scientific journal.
To publish in this journal, it is a premise to take part in the master course wind power, hydro power and biomass usage at the department of Energy, Building Services and Environmental Engineering of the Münster University of Applied Sciences.
Students receive an equivalent of 2.5 credit points (European Credit Transfer and Accumulation System – ECTS) for their engagement in the course and for publishing a short review article of at most 3 000 words in this periodical. The publication process closely mimics the typical publication procedure of a regular journal.
The peer-review process, however, is conducted within the group of course-participants.
Although being just an exercise, we think that publishing the outcome of this course in a citable manner is not only promoting the motivation of our students, but may also be a helpful source of introductory information for researchers and practitioners in the field of renewable energies. We encourage students to write their articles in English, but this is not mandatory. The reader will thus find a few articles in German language.
To further encourage students practicing English writing, perfect grammar is not part of the assessment.
We especially thank our students for working with LATEX on Overleaf, although LATEX is new to some of them. In this way, the editorial workload was reduced to a minimum. We also thank our students for sharing their work under the creative commons attribution licence (CC-BY). We appreciate their contribution to scientific information, being available to every person of the world, almost without barriers. We also thank the corresponding authors and publishers of the cited work, for granting permission.
Meanwhile, renewable energy sources such as hydropower, solar and wind energy and biomass are increasingly being used to reduce dependence on fossil fuels and thus counteract the ongoing global warming. However, these are also associated with environmental impacts. To that effect, this article takes a closer look at tidal power plants, which are classified as hydroelectric power plants, by conducting a systematic literature review. The results show that the strength and form of the environmental impact depends on the specific location and type of plant. Tidal power plants have an impact on the habitats of marine animals and thus influence their behavior and population. In addition, the operation of tidal power plants changes the sediment distribution, causes a reduction in current velocities and a change in current direction in the surrounding area and leads to a change in wave height. The construction of the power plants is associated with noise, which primarily causes changes in the behavior of some species. Furthermore, the electromagnetic fields generated can also affect marine life. In order to assess the environmental impact of tidal power plants in comparison to other renewable energies, further studies should focus on the environmental impact of the different technologies in relation to the energy yield.
This article discusses the use of artificial intelligence
in the wind energy industry, particularly in addressing
challenges and optimizing the expansion of renewable
energies in Germany. It highlights the application
of artificial intelligence in wind forecasts and yield
predictions, bird detection, wind turbine and farm
design, condition monitoring, and predictive maintenance.
Additionally, it introduces the “WindGISKI”
research project, which aims to use artificial intelligence
to identify new areas for wind turbines. The
project utilizes a neural network to analyze and predict
flight routes, potentially reducing bird mortality.
The document also emphasizes the potential broader
applications of “WindGISKI” in other fields of activity,
such as land use planning and city development.
Overall, it underscores the significant role of artificial
intelligence in addressing challenges in wind energy
and outlines the potential for artificial intelligence
to drive the expansion of renewable energies while
addressing key obstacles.
Wind turbine structures take a major role in the
modern conversion to renewable energy sources and
contribute to the creation of a greener world. In recent
years, the development and installation of wind
turbines have seen rapid growth. However, with the
increasing capacity and size of wind farms worldwide,
there are growing concerns about the safety and reliability
of these installations. Therefore, structural
health monitoring and the detection of damage to
wind turbines have gained considerable importance in
research. Wind turbine blades are particularly susceptible
to various types of damage due to environmental
influences. This article provides an overview of signal
responses, sensors used and non-destructive testing
techniques in the field of damage detection on wind
turbine blades. The intention of the article is to give
an insight into the possibilities of structural health
monitoring and at the same time to point out unsolved
problems in this field.
The preservation of water bodies continuity is fundamental
for aquatic communities, particularly for fish
populations. Various structures impede watercourse
continuity, impacting fish migration and habitat distribution.
Conventional fish passages often fall short
in diverse scenarios, prompting the development of
specialized solutions. This article proposes a criteria
catalog for these special fish passage solutions based
on DWA leaflet DWA-A 509. It discusses the need
for these solutions, presents a selection of specialized
options, and outlines criteria from DWA-M 509, construction
guidelines, and economic perspectives. It
scrutinizes criteria ranging from target fish species to
cost considerations. Three examples, including the
Runserau fish lift, the bristle ramp fish lock, and the
Fishcon sluice, illustrate these specialized solutions,
their functionalities, advantages, and drawbacks. Additionally,
the article compiles criteria from industry
standards and guidelines into a comprehensive evaluation
catalog. The criteria, when applied, assist in the
selection of suitable fish passage solutions based on
specific site conditions and fish species requirements.
This holistic approach aims to optimize fishway selection,
fostering the ecological sustainability of watercourses.
However, this catalog remains dynamic
and open to expansion with evolving research and
practical application, urging further exploration and
validation of these criteria through diverse case studies
and technological advancements in the field.
This study identifies supply options for sustainable urban energy systems, which are robust to external system changes. A multi-criteria optimization model is used to minimize greenhouse gas (GHG) emissions and financial costs of a reference system. Sensitivity analyses examine the impact of changing boundary conditions related to GHG emissions, energy prices, energy demands, and population density. Options that align with both financial and emission reduction and are robust to system changes are called “no-regret” options. Options sensitive to system changes are labeled as “potential-risk” options.
There is a conflict between minimizing GHG emissions and financial costs. In the reference case, the emission-optimized scenario enables a reduction of GHG emissions (-93%), but involves higher costs (+160%) compared to the financially-optimized scenario.
No-regret options include photovoltaic systems, decentralized heat pumps, thermal storages, electricity exchange between sub-systems and with higher-level systems, and reducing energy demands through building insulation, behavioral changes, or the decrease of living space per inhabitant. Potential-risk options include solar thermal systems, natural gas technologies, high-capacity battery storages, and hydrogen for building energy supply.
When energy prices rise, financially-optimized systems approach the least-emission system design. The maximum profitability of natural gas technologies was already reached before the 2022 European energy crisis.
Die Planung urbaner Energiesysteme wird durch die zunehmende Verbreitung sektorgekoppelter Technologien und neuer Verbrauchssektoren immer komplexer. Klassische Planungsmethoden kommen an ihre Grenzen. Die Energiesystemmodellierung (ESM) bietet eine Möglichkeit, ein Energiesystem hinsichtlich der Kosten und der Treibhausgas (THG)- Emissionen zu optimieren. Gleichzeitig ergibt sich aus der Energiewende und angestrebten THG-Neutralität ein akuter Handlungsbedarf. Dies gilt auch für die 1 500 Kasernen in Deutschland. Im Rahmen dieser Arbeit werden der bestehende Modellierungsprozess des Spreadsheet Energy System Model Generator (SESMG) erweitert, indem Herausforderungen der Modellierung und Optimierung von Kasernen identifiziert und Lösungsansätze hierzu entwickelt werden.
Diese Arbeit basiert auf der ESM einer realen Kaserne. Es kann das Urban District Upscaling Tool zur Erstellung der für den SESMG benötigten Modelldefinition verwendet werden. Die Open-Source Datenbank SESMG-Data, kann automatisch die benötigte Standard Parameter Tabelle mit zugehörigem Bericht generieren. Weiterhin wurde ein Energieaustauschmodell vorgestellt, das den Energieaustausch zwischen Kasernen eines Bilanzkreises ermöglicht. Ein Fokus liegt auf der Abbildung zukünftiger Ausbaupläne.
Dazu wurden kasernenspezifische Gebäudeprofile entwickelt, die gemittelte spezifische Energiebedarfe und weitere Parameter zur Berechnung der Wand-, Fenster-, und Dachfläche enthalten. Der spezifische Wärmebedarf kann durch einen Faktor an die Baualtersklasse angepasst werden. Mit Hilfe statistischer Kennwerte lässt sich ein geeignetes Standardlastprofil für verschiedene Gebäudeprofile auswählen. Zur Reduktion der Komponenten im Energiesystemoptimierungsmodell (ESOM) können die Dachflächenpotenziale von Photovoltaikanlagen zusammengefasst werden. Da Kasernen nur eine Bilanzgrenze besitzen, können zudem auch die Strombedarfe der einzelnen Gebäude zusammengefasst werden. Damit lassen sich gleichzeitig dezentrale Batteriespeicher als Komponente des ESOMs ausschließen. Die Potenzialflächen von Erdwärmepumpen können zusammengefasst werden, wobei Abstands- und Belastbarkeitsgrenzen eingehalten werden müssen.
Kasernen verfügen häufig über Bestandswärmenetze, die im ESOM gesondert berücksichtigt werden müssen. Um dieses Bestandswärmenetz abzubilden, können die Verteilleitungen manuell nachgezeichnet werden und in einer Vormodellierung mit dem SESMG mit geringeren Kosten angesetzt werden. Die in dieser Arbeit entwickelten Methoden sind allgemeingültig für Kasernen. Die Übertragbarkeit der kasernenspezifischen Gebäudeprofile ist aufgrund der unterschiedlichen Nutzung von Kasernen nur eingeschränkt möglich. Der bestehende Modellierungsprozess wurde um kasernenspezifische Prozessschritte erweitert und visualisiert. Zukünftige Modellierungen von Kasernen können zur Validierung der Ergebnisse und für weitere Anpassungen, wie z. B. die Erstellung einer kasernenspezifischen Datenbank, genutzt werden.
Die Transformation der Energiesysteme im Rahmen der Energiewende macht diese durch zusätzliche Komponenten und Wechselwirkungen immer komplexer. Das ökonomische und ökologische Potenzial, dass sich aus der Nutzung der Synergien dieser Komponenten ergeben kann, erfordert eine gemeinsame Betrachtung des gesamten Energiesystems hinsichtlich sämtlicher Energie- und Verbrauchssektoren.
Die Energiesystemmodellierung stellt eine geeignete Methode zur Modellierung und Optimierung dieser urbanen Energiesysteme dar. Mit dem „Spreadsheet Energy System Model Generator“ (SESMG) hat die FH Münster ein Open Source Tool entwickelt, das die Betrachtung urbaner Quartiere ermöglicht. Diese können hinsichtlich verschiedener Zielkriterien wie z. B. monetären Kosten und THG-Emissionen optimiert werden. Die tabellenbasierte Eingabe erfordert keine Programmierkenntnisse. Das implementierte Urban District Upscaling Tool erleichtert die effektive Modellierung auch größerer Systeme. Die automatisierte Ergebnisaufbereitung ermöglicht eine schnelle Analyse der Ergebnisse.
The annual wastewater flow that is treated by public
wastewater treatment plants in Germany amounts
to approx. 10 ∗ 10^9 m3/a and forms an ”artificial” hydropower
potential that can be used for energy generation
or recovery. In the context of this paper, energy
recovery in the outlet of wastewater treatment plants
is examined using the specific example of the water
wheel at the Warendorf central wastewater treatment
plant. The ”artificial” hydropower potential can be
roughly estimated at up to 20 to 105 GWh/a , whereby
this is largely dependent on the hydraulic gradient.
The strong variance results, among other things, from
the findings of the water wheel operation in Warendorf.
The decisive aspect here is the differential factor,
which describes the deviation between the theoretical
and actual energy yield of the water wheel. The
factor includes maintenance work, downtimes and insufficient
inflows, which are associated with a loss of
output. In the case study, the annual energy recovery
amounts to approx. 2 % of the annual electricity consumption
of the wastewater treatment plant and can
be estimated to 23,500 kWh (2022). In the context
of the economic analysis, it can be seen that despite
the ”low” yield, economic operation is possible if the
system is viewed as a long-term investment - payback
period of the example is approx. 14,5 years. The
27-year operation (1996 - 2023) of the water wheel
at the Warendorf central wastewater treatment plant
confirms this and important findings on successful
practical operation can be shown in the context of
this paper.
This document presents a comparative analysis of
horizontal and vertical small wind turbines for urban
areas in three power classes up to 10 kW in different
categories. The main objective was to conduct a market
analysis to assess the marketability of these wind
energy systems. The aim was to make it easier for
potential customers to make a decision. However, due
to the limited availability of data, the project encountered
considerable difficulties. As a result, the study
became a comparative assessment, which led to results
that may not be readily transferable to urban environments,
slightly missing the original objective of the
study. The results underline the difficulties associated
with conducting a comprehensive market analysis in
this sector and highlight the need for an independent
series of tests under specific conditions. The paper
concludes with a plea for future research efforts to
adapt data collection methods to urban conditions in
order to improve the relevance and applicability of
such studies in practice.
The construction and operation of hydropower plants
for energy generation is a major issue in sustainable
energy production. Nevertheless, hydropower plants
have a negative impact on fish populations. It is crucial
to understand the causes and consequences of fish
mortality in hydropower plants in order to find sustainable
solutions that reconcile the need for energy
with the conservation of aquatic ecosystems. This
article examines the fish protection measures that can
be implemented to reduce fish mortality and maintain
ecological balance. Based on the main literature reviewed,
this article mainly refers to Germany in terms
of studies carried out and hydropower plants.
This article analyses the impact of robotics on the
operation and maintenance (O&M) of offshore wind
turbines (OWTs), with a particular emphasis on the
challenges and benefits. As the world’s reliance on
renewable energy, particularly offshore wind, increases
to reduce climate change, the growing number of
OWTs requires effective O&M. Challenges consist
of logistics, accessibility and high costs. The paper
presents the application of climbing robots, unmanned
aerial vehicles and underwater robots to overcome
these challenges.
The combination of multiple robotic platforms, such
as autonomous surface vehicles and autonomous underwater
vehicles, represents a collaborative approach
to O&M. Obstacles include the need for accurate navigation,
building trust between humans and robots,
and research into artificial intelligence.
In conclusion, the integration of robotics in O&M
presents considerable advantages, increasing efficiency,
safety and cost-effectiveness. Further progress and
research into artificial intelligence are crucial in achieving
complete automation, which will transform the
O&M of OWTs.
The pursuit of Offshore Wind Energy (OWE), integral
to the German government’s ambitious renewable
energy goals raises concerns about the environmental
impact of noise emissions on marine life. This paper
delves into the theoretical background of Offshore
Wind Turbine (OWT) noise, exploring its various
phases from the survey to decommission. It examines
the types and causes of noise emissions, their effects
on marine wildlife and potential mitigation measures.
Highlighting the regulatory framework in Germany,
the paper emphasises the need for nuanced approaches
to balance renewable energy objectives with marine
ecosystem preservation.
This review paper provides an initial overview of the
state of the art of common corrosion protection methods
for offshore wind turbines. The functions of the
individual corrosion protection methods and their
interaction are explained. In addition, the specific corrosion
protection of different zones and components
of an offshore wind turbine will be discussed. Finally,
some information is given on current and possible
future developments in this subject area.
This paper outlines the three main areas relevant
to dismantling: the rotor blades, hub and nacelle,
the tower and the foundation. The paper discusses
the dismantling procedures, including the removal of
the top structure, the tower and the foundation, and
evaluates various methods of dismantling the tower,
such as modular dismantling, collapse blasting, folding
blasting, wrecking ball demolition and hydraulic
ram demolition. The assessment of these methods
in practice and the potential challenges and considerations
for future dismantling, particularly as wind
turbine heights increase, are also addressed.
The upscaling of wind turbines has been increasing in
recent years and will continue to play a significant role
in the future, as it allows for the reduction of electricity
generation costs. Various challenges arise when it
comes to upscaling. This article summarizes the technical
challenges associated with upscaling wind turbines
and presenting their problem-solving approaches
and research trends based on other reviews. It was
found that the most frequently cited challenges are
related to individual components, such as rotor blades,
drive train, generator, tower, and noise impact.
For rotor blades, the challenges are increased flexibility,
more aeroelastic vibrations, increased wear,
interferences with radar and transportation difficulties.
Proposed solutions include the use of carbon-fiber
blades, prebending, novel paints, and for transportation,
segmented rotor blades and on-site manufacturing.
In the gearbox, torque increases, leading to
higher weight and susceptibility to errors. As a result,
the trend is moving towards gearless systems with
permanent magnet synchronous generators. Transportation
is the major issue with towers, which can
be resolved with on-site manufacturing. In terms of
noise emission, reducing aerodynamic noise plays the
most significant role.
As Germany aims to increase its utilization of wind
power, the potential threat to bird populations due
to this expansion is a controversial issue. This paper
aims to collect data on the magnitude of bird strikes
on wind turbines, review existing protective measures
and explore innovative solutions. After a thorough
examination of the literature, it was concluded that
although the impact on bird populations is significant,
it may be overemphasized in popular debates. This
statement is not final as further research is necessary
to assess the impact of bird strikes and explore new
solutions. Comprehensive studies on this specific topic
in Germany are limited, which makes a thorough evaluation
challenging. While there are measures in place
to protect species that may be negatively impacted, it
is possible that these measures will not be adequate
for all of them. While several innovative methods
are under examination, progress in testing and implementation
is slow. Lastly, an information problem
was identified. Since the topic is highly politicized
and polarizing, it is crucial to provide the public with
accessible and reliable information on the discussed
themes. This is currently not the case due to a lack
of data and missing information campaigns.
Wind energy plays a major role among renewable
energies. Its expansion is therefore important in order
to achieve the climate targets. Repowering is an
important element in the expansion of wind energy.
On the one hand, it offers a solution for many wind
turbines in Germany that are no longer subsidised due
to their age. On the other hand, modern turbines are
significantly more powerful and enable more efficient
land utilisation. This article provides an overview of
the most important aspects of onshore repowering.
There is a lot to consider when repowering wind turbines.
The legal situation for repowering aims to
be improved through simplified authorisation procedures.
Even though efforts are being made by the
government, there is still room for improvement. The
repowering potential is also dependent on the various
distance regulations to residential buildings in
the federal states. These regulations might also be
improved in the future. Another aspect is the remuneration,
which is now closer to market developments
due to the market premium model. It is also subject
to greater competition as a result of the tendering
process. At the same time, interest rates and turbine
prices have risen, which creates economic challenges
for the operators of future wind farms. Last but not
least, repowering also depends on public acceptance.
This is also to be regulated by law in the future.
When simulating and optimizing urban energy systems, the focus is usually on minimizing financial costs or greenhouse gas (GHG) emissions. As energy systems transition towards a growing share of renewable energy sources and technological complexity, environmental impacts that affect more than just GHG emissions, such as resource extractions, water and land use impacts or impacts on human health, are becoming increasingly relevant.
To address this gap, this thesis introduces an automated coupling procedure for energy system modeling (ESM) and life cycle assessment (LCA). The implementation includes general recommendations and a practical coupling of the Open Energy Modelling Framework (oemof) based Spreadsheet Energy System Model Generator (SESMG) with a suitable LCA software.
The LCA procedure involves goal and scope definition, inventory analysis, impact assessment, and interpretation. To adapt these steps to different energy system models, the LCA should be attributional, process-based and territorial. Further, the openLCA software by Green-Delta serves as a suitable soft-linking tool. The main challenge of the coupling procedure is the inventory analysis. Data collection faces limitations, reasoned by the commercialization and high maintenance efforts in open-source databases. After evaluating free databases, the Prozessorientierte Basisdaten für Umweltmanagement-Instrumente (ProBas) database of the Umweltbundesamt emerged as the most suitable choice for the coupling. However, also this database lacks traceability of datasets or compatibility with a comprehensive impact assessment.
A generalized framework for the LCA application of energy systems was developed. The framework is based on an ex-post LCA assessment that considers the combination of the two approaches within every step of the procedure. Main considerations of this framework include automatic calculations of the inventory analysis and the impact assessment for different energy technologies, as well as calculations summed up for all technologies of energy system scenarios. Further, technology mapping and data harmonization are essential considerations for the automatic coupling and double counting of impacts needs to be avoided.
Subsequently, the framework is realized with the adaption of the SESMG. Its database-independent realization allows compatibility with different databases in openLCA. For the selected ProBas database, the tool can be used with different available energy technologies. The use of unit processes is encouraged for data harmonization. Result interpretation of the LCA (in general or with the SESMG) should not solely focus on the absolute values of the impact categories, but rather on the comparative strengths among scenarios and technologies.
The successful application to a reference single-family building using the ProBas database revealed varied environmental impacts, in relation with a higher reduction in GHG emissions, with an increase of 11 % in terrestrial acidification impacts in the emission-optimized scenario. These findings emphasize a more comprehensive perspective on environmental impacts and provide a valuable validation of the developed methodology.
Future research should include the improvement of data harmonization, the inclusion of more datasets for a more customized analysis of energy systems and more applications. The coupled approach offers a promising avenue for gaining deeper insights into optimizing urban energy systems.
The Spreadsheet Energy System Model Generator (SESMG) is a tool for modeling and optimizing energy systems with a focus on urban systems. The SESMG is easily accessible as it comes with a browser-based graphical user interface, spreadsheets to provide data entry, and detailed documentation on how to use it. Programming skills are not required for the installation or application of the tool. The SESMG includes advanced modeling features such as the application of the multi-energy system (MES) approach, multi-objective optimization, model-based methods for reducing computational requirements, and automated conceptualization and result processing of urban energy systems with high spatial resolution. Due to its accessibility and the applied modeling methods, urban energy systems can be modeled and optimized with comparatively low effort.
Entwicklung eines Konzeptes zur Nachrüstung von Regenklärbecken mit technischen Regenwasserfiltern
(2023)
The Educational Journal of Renewable Energy Short Reviews (EduJRESR, formally published as `EGU Journal of Renewable Energy Short Reviews') is a teaching project rather than a regular scientific journal. To publish in this journal, it is a premise to take part in the master course wind power, hydro power and biomass usage at the department of Energy, Building Services and Environmental Engineering of the Münster University of Applied Sciences.
Students receive an equivalent of 2.5 credit points (European Credit Transfer and Accumulation System - ECTS) for their engagement in the course and for publishing a short review article of at most 3000 words in this periodical. The publication process closely mimics the typical publication procedure of a regular journal. The peer-review process, however, is conducted within the group of course-participants.
Although being just an exercise, we think that publishing the outcome of this course in a citable manner is not only promoting the motivation of our students, but may also be a helpful source of introductory information for researchers and practitioners in the field of renewable energies. We encourage students to write their articles in English, but this is not mandatory. The reader will thus find a few articles in German language. To further encourage students practicing English writing, perfect grammar is not part of the assessment.
We especially thank our students for working with LaTeX on Overleaf, although LaTeX is new to some of them. In this way, the editorial workload was reduced to a minimum. We also thank our students for sharing their work under the creative commons attribution licence (CC-BY). We appreciate their contribution to scientific information, being available to every person of the world, almost without barriers. We also thank the corresponding authors and publishers of the cited work, for granting permission to reuse graphics free of charge. All other figures had to be replaced or removed prior to publication.
The use of wind power is rapidly expanding worldwide. It is important to examine the impact of wind turbines on the environment to see if they provide a net benefit and to identify potential for improving. Therefore life cycle assessments (LCA) of different wind turbine types are compared in this short review. The results are then shown side by side in tables for comparison. Overall the LCAs show that wind turbines compensate the required energy and emitted pollutants after approx. 6-16 months. The energy payback period (EPP) for 2 MW onshore wind turbines remained roughly the same since 2009 with approximately 7 months. Onshore wind turbines have a higher impact due to emissions but a shorter EPP than offshore wind turbines. The estimated service life of 20 years should be maximized to ensure a high energy yield ratio. The biggest impact on the environment results from the processes to provide the building material e.g. steel and cement. That impact could be reduced by 20 % if recycled steel would be used. It is shown that wind power is one of the cleanest energy sources. But further investigations in material processing and recycling are important to improve the eco-balance of wind turbines.
This review is about where and which tidal power systems are currently deployed. It starts with an insight into the variety of different tidal power systems. With the help of a list from the European Marine Energy Center about currently used systems for tidal power plants, it quickly becomes apparent that two systems stand out. These are the vertical and horizontal turbines. The latter are particularly common, as they are used for both tidal stream and tidal range power plants. Determining the regions with high potential for tidal power is not always easy due to the many influencing factors. Influencing factors are, for example form and conditions of the seabed, topographical features of the coast or currents in the sea [1]. Therefore, each region must be considered separately. n this paper the focus is on the UK, the literature shows that the coastal regions around the UK provide about 50 TWh/year of the European tidal power potential. This is due to the location between the oceans and the geological conditions, which act as a channel for the tides. The two areas with high potential where planning
and construction of tidal power plants is currently underway are in the north of Scotland and in the southwest of England in the Bristol Channel.
This review paper presents a short overview of current power system modelling tools especially used for analysing energy and electricity systems for the supply and demand sector. The main focus of this review lies on open source tools and models which are written and used in the programming language “Python”. The modelling tools are represented in a comprehensive table with key information. Five modelling tools with an open source license can be filtered out. The modelling tool PyPSA can be considered as a high performing tool especially as the gap between power system analysis tool (PSAT) and energy system modelling tool.
Stormwater tree pits with storage elements enable the irrigation of urban trees and can potentially act as decentralized rainwater retention basins. This paper mainly focuses on analyzing this potential. Field tests were conducted to investigate the irrigation behavior and the storage effect of a storm water tree pit system using Perl hoses as irrigation elements over a period of two years.
The rainfall, storage volumes, and soil moisture within the employed planting pit were measured.
With the help of system modeling, the retention ability of the storm water tree pit system was analyzed. The available storage volume was sufficient to irrigate trees for several days. During the measurement period, about 15% of the inflowing rainwater was fed to the root zone of the tree. With practical storage volumes of 200 to 300 m3/ha, a remarkable amount of water from heavy rainfall could be completely stored, thus significantly reducing the risk of flooding. The retention effect and irrigation behavior largely depend on the soil conditions and the technical possibilities of the equipment supplying the root area (in this case, Perl hoses). Further investigations are required to determine the influence on the growth conditions of trees and optimize of the system for discharge into the root zone.
For the increasingly important storage of renewably generated electricity, this review explains the construction of a surface and underground pumped storage
power plant. The problems for the construction of an underground pumped storage power plant are further listed. These are geological, environmental and
economic problems as well as a low acceptance by the population. The geological problems are concerns about leaching of minerals and heavy metals as well as the statics of the cavities. Mining companies in Germany are obligated to renaturalize the landscape areas again, which could be realised by a lake. Furthermore, care must be taken to ensure that the mine water does not come into contact with the groundwater. According to a survey by RISP on the subsequent use of the mine areas for an underground pumped
storage power plant, the acceptance of the population is over 70 percent. The economic consideration concludes that the arbitrage profit for a difference between off-peak and peak of 10 €/MWh is about 2.7 M€/a and for 100 €/MWh about 27.3 M€/a. With investment costs of about 630 M€, despite the assumption of 100 €/MWh, more than 20 years are needed for an underground pumped storage power plant to be amortized. The acceptance could be increased by creating a lake as a recreation area as well as being used as an upper storage reservoir. Thus, the cost of renaturation decrease when combined with the creation of the storage basin. The problem of ground conditions can be solved by creating new cavities by means of tunnel boring at an inclination. For static safety as well as against leaching of minerals and heavy metals, the cavity walls can be sealed with reinforced concrete. The technology of underground pumped storage power plants can be used for better utilisation of renewable energies. This is especially in flat and densely populated regions a possibility to store energy, because the main part of the power plant is underground.
Indicators for the optimization of sustainable urban energy systems based on energy system modeling
(2022)
Background: Urban energy systems are responsible for 75 % of the world's energy consumption and for 70 % of the worldwide greenhouse gas emissions. Energy system models are used to optimize, benchmark and compare such energy systems with the help of energy sustainability indicators. We discuss several indicators for their basic suitability and their response to changing boundary conditions, system structures and reference values. The most suitable parameters are applied to four different supply scenarios of a real-world urban energy system.
Results: There is a number of energy sustainability indicators, but not all of them are suitable for the use in urban energy system optimization models. Shortcomings originate from the omission of upstream energy supply chains (secondary energy efficiency), from limited capabilities to compare small energy systems (energy productivity), from excessive accounting expense (regeneration rate), from unsuitable accounting methods (primary energy efficiency), from a questionable impact of some indicators on the overall system sustainability (self-sufficiency), from the lack of detailed information content (share of renewables), and more. On the other hand, indicators of absolute greenhouse gas emissions, energy costs, and final energy demand are well suitable for the use in optimization models. However, each of these indicators only represents partial aspects of energy sustainability; the use of only one indicator in the optimization process increases the risk that other important aspects will deteriorate significantly, eventually leading to suboptimal or even unrealistic scenarios in practice. Therefore, multi-criteria approaches should be used to enable a more holistic optimization and planning of sustainable urban energy systems.
Conclusion: We recommend multi-criteria optimization approaches using the indicators of absolute greenhouse gas emissions, absolute energy costs, and absolute energy demand. For benchmarking and comparison purposes, specific indicators should be used and therefore related to the final energy demand, respectively the number of inhabitants. Our example scenarios demonstrate modeling strategies to optimize sustainability of urban energy systems.
In Germany, the current sectoral urban planning often leads to inefficient use of resources, partly because municipalities lack integrated planning instruments and argumentation strength toward politics, investors, or citizens. The paper develops the ResourcePlan as (i) legal and (ii) a planning instrument to support the efficient use of resources in urban neighborhoods. The integrative, multi-methodological approach addresses the use of natural resources in the building and infrastructural sectors of (i) water (storm- and wastewater) management, (ii) construction and maintenance of buildings and infrastructure, (iii) urban energy system planning, and (iv) land-use planning. First, the development as legal instrument is carried out, providing (i) premises for integrating resource protection at all legal levels and (ii) options for implementing the ResourcePlan within German municipal structures. Second, the evaluation framework for resource efficiency of the urban neighborhoods is set up for usage as a planning instrument. The framework provides a two-stage process that runs through the phases of setting up and implementing the ResourcePlan. (Eco)system services are evaluated as well as life cycle assessment and economic aspects. As a legal instrument, the ResourcePlan integrates resource protection into municipal planning and decision-making processes. The multi-methodological evaluation framework helps to assess inter-disciplinary resource efficiency, supports the spatial identification of synergies and conflicting goals, and contributes to transparent, resource-optimized planning decisions.
Mechanical ventilation of buildings is generally based on steadily operating systems. This field is well known and established. But, an approach based on time-varied supply flow rates might improve indoor air quality, comfort, and energy consumption. Typical time-scales of the variation are in the order of seconds or minutes. Until now, the effects of unsteady ventilation scenarios are not fully described and so, reliable dimensioning rules are missing. Hence, with a better understanding of the flow in unsteady ventilation, systems can be calculated and optimised. To understand the effective mechanisms and derive functional relations between the flow field and variation parameters, full-field optical flow measurements are executed with a particle image velocimetry (PIV) system. Experiments are conducted under isothermal conditions in water in a small-scale room model (1.00 m × 0.67 m × 0.46 m) with two swirl ceiling diffusers, Reynolds-scaling assures similarity. In a series of experiments, the effects of different unsteady ventilation strategies on the flow fields are investigated and compared to steady conditions with the same mean exchange rate. Mean exchange rates, signal types, periods, and amplitudes are varied. Time-averaged normalised velocity fields already indicate notable differences between steady and unsteady cases especially for lower exchange rates: the distribution is more homogeneous in unsteady scenarios compared to steady conditions, and low-velocity areas are reduced while the mean velocity of the room increases. So, unsteady ventilation might be beneficial in terms of improved ventilation and energy savings in partial-load operation. Fast Fourier Transformation (FFT) analyses of the mean velocity for each field over the whole series detect the main frequency of the volume flow variation. By dividing the velocity field into smaller areas, this main frequency is still detected especially in the upper part of the room, but side frequencies play a role in the room as well.
Programmierung von Open Source Software in der Energiewirtschaft nimmt seit Beginn der 2000er stetig zu. Dies gilt sowohl für den Bereich der Forschung und Entwicklung, als auch für die Industrie und Wirtschaft. So werden beispielsweise Modelle zur Planung und Optimierung von Energiesystemen umgesetzt. Eine Open Source Veröffentlichung ist in diesem Forschungsfeld besonders wichtig, um die Überprüfbarkeit von Modellannahmen sowie der Vergleichbarkeit verschiedener Modellansätze zu garantieren. Einer Open-Source Veröffentlichung stehen jedoch häufig die Hürden von hohem Fristendruck, fehlender Finanzierung und fehlendem Detailwissen der Publizierenden entgegen. Deshalb bleiben diese Softwareprodukte meist im Entwurfsstadium und sind daher schwierig wieder zu verwenden.
Mithilfe des neu erarbeiteten Schritt-für-Schritt Leitfadens zur standardisierten Implementierung einer Open Source Software, wird die Hürde und der zeitliche Aufwand zur Standardisierung von Open Source Repositories weitestgehend reduziert. Hierbei wird für jedem Bestandteil des zu standardisierenden Repositorys eine umfassende Erklärung der üblichen Standards sowie eine Empfehlung für unterstützende Softwarelösungen ausgesprochen.
Der Leitfaden orientiert sich an den aus der ISO 12207 resultierenden Phasen des Softwarelebenszyklus und ermöglicht einen Einstieg zu jedem Entwicklungsstand der Software. Seine grafische Aufbereitung in Form eines Prozessablaufplans erleichtert die Einschätzung des individuellen Status der Standardisierung eines vorliegenden Open Source Projektes. Als Treiber der Standardisierung eines Open Source Projektes sind insbesondere die bessere Lesbarkeit, Wartbarkeit und Testbarkeit der standardisierten Open Source Software wichtig.
Bei der Anwendung auf das bereits bestehende Open Source Projekt des Spreadsheet Energy System Model Genarators fiel auf, dass ein verspäteter Einstieg in ein systematisches Vorgehen (wie er mit dem Leitfaden dieser Arbeit gegeben wird) zu erheblichen Mehraufwand bei der Standardisierung führen kann. Dennoch konnten im Zuge der Umsetzung des erarbeiteten Leitfadens weitreichende Verbesserungen des Projektes vor dem Hintergrund der Standardisierung erreicht werden (z. B. Versionierung & Wartbarkeit).
Insgesamt lässt sich festhalten, dass eine frühestmögliche Standardisierung der Open Source Repositories durchgeführt werden sollte, um spätere Mehrarbeit zu vermeiden und die frühstmögliche Wiederverwendbarkeit für Dritte zu gewährleisten.
The energy demand of the residential sector contributed to about 29 % of Germany’s final energy consumption in 2020. For the planning and optimization of energy systems, an understanding of the temporal energy consumption is necessary. This paper discusses tools for estimating these load profiles. Load profiles for electricity, space heating and domestic hot water (DHW) are investigated. A total of ten tools were applied. It turns out that the selected load profiles are dependent on the field of application. Load profiles influence the results of energy system modeling and therefore it is important to differentiate load profile tools. Standardized load profiles are well suited when a large number of buildings are considered. Stochastic load profiles, behavioral load profiles and the reference load profiles are well suited for building-specific simulations. Physical load pro- files are well suited for single building models, but as soon as several buildings are considered, the input effort for a sufficient accuracy is high.
Floating offshore wind (FOW) holds the key to 80 % of the total offshore wind resources, located in waters of 60 m and deeper in European seas, where traditional bottom-fixed offshore wind (BFOW) is not economically attractive.
Many problems affecting floating offshore wind turbines (FOWT) were quickly overcome based on previous experience with floating oil rigs and bottom-fixed offshore wind. However, this technology is still young and there are still many challenges to overcome.
This paper shows that electrical failures are amongst the most significant errors of FOWT. The most common cause was corrosion. It is also stated that the control system is most often affected, and that the Generator is frequently involved. Material corrosion is also the key factor when it comes to the most common overall reason for failures.
A particular attention must be paid to mooring line fracture. Mooring lines are especially vulnerable to extreme sea conditions and the resulting fatigue, corrosion, impact damage, and further risks.
It must be stated that the primary challenge is that of economics. Over time technological costs will decline making FOW more competitive and hence attractive for greater depth.
Assessment of noise mitigation measures during pile driving of larger offshore wind foundations
(2021)
Wind energy is an important source of electricity generation, but the construction of offshore wind foundations causes high underwater sound pressure, harming marine life. In this context limiting values for underwater noise emissions were set to protect the marine flora and fauna. Therefore, noise mitigation measures during pile driving are mandatory to comply with these limits. Current development in the wind industry lead to increasing wind turbine sizes, requiring a larger pile diameter, which leads to higher underwater noise emissions. As a result, the state of the art noise mitigation systems might not be sufficient and a combination of different technologies is necessary. This article focuses on the issue of noise mitigation during pile driving with respect to large pile sizes. First, the most tested and proven noise mitigation techniques (big bubble curtain, hydro sound damper, and IHC-noise mitigation system) are described, following an analysis of noise reduction measurements in applications at different offshore wind farm projects. In the end the suitability of current noise mitigation systems for large monopiles is evaluated, regarding their effectiveness and practicability.
Wind energy conversion systems have attracted considerable attention as a renewable energy source due to depleting fossil fuel reserves and environmental concerns as a direct consequence of using fossil fuel and nuclear energy sources. The increasing number of wind turbines increases the interest in efficient systems. The power output of a wind energy conversion system depends on the accuracy of the maximum power tracking system, as wind speed changes constantly throughout the day. Maximum power point tracking systems that do not require mechanical sensors to measure the wind speed offer several advantages over systems using mechanical sensors. In this paper four different approaches that do not use mechanical sensors to measure the wind speed will be presented; the assets and drawbacks of these systems are highlighted, and afterwards the examined algorithms will be compared based on different characteristics. Finally, based on the analysis, an evaluation is made as to which of the presented algorithms is the most promising.
Wind energy has steadily gained importance in the generation of renewable energy over the last 25 years. A wind turbine has an average life expectancy of about 25 years. After that, thermoplastic composite materials from the rotors, among other things, accumulate and have to be recycled. Previous methods, such as landfilling, incineration and pyrolysis, have not yet proven to be effective in terms of the circular economy because the recycled material cannot be reused for equivalent products. The use of thermoplastic materials can be a sensible alternative, as thermoplastic resins can be recycled almost without loss of value due to their properties. Recycling of fibreglass is also possible with less loss of stiffness. In the future, it will be crucial to scale up thermoplastic rotor blades and create a market for the recycled material.
Diese Arbeit befasst sich mit Kostentrends in Zusammenhang mit technologischem Lernen von Windenergie an Land in den USA, in Deutschland und weltweit. Ziel dieser Arbeit ist es, eine Lernkurve für Windenergie an Land zu bestimmen. Dafür wurden Daten zu Stromgestehungskosten (LCOE) und Kosten für die Installation (COP) von Windenergieanlagen (WEA) im Zeitraum von 1983 bis einschließlich 2020 gesammelt, grafisch dargestellt und weitergehend ausgewertet. Die grafische Darstellung der Datenlage verdeutlicht die zeitliche Entwicklung der Technologie. Zur Beschreibung dieser Lernkurven wurden die Progress Ratio (PR) und Learning Rate (LR) in fünf unterschiedlichen Modellen bestimmt. Anhand derer sich in Kombination mit der zukünftig installierten Leistung von WEA eine Prognose über zukünftige Kosten ableiten lässt. Die ermittelten LR bewegen sich zwischen 13 % und 28 %, woraus sich LCOE im Jahr 2030 zwischen 44,03 US$/MWh und 61 US$/MWh ergeben.
Because of the rapid expansion and widespread application of wind energy the overall environmental impacts of wind power plants have increased as well. For the further development of wind power, methods to lessen the adverse effects wind power has on avian populations have to be implemented. This review aims to find effective methods to reduce avian collision rates with wind turbines and that therefore can reduce bird fatality rates.
For the assessment the different mitigation methods, for which concrete data was found, are compared with each other regarding the hypothetical effort of implementation and effectiveness in reducing avian collision rates with wind turbines.
These methods are:
(a) Coloring of rotor blades
(b) Coloring of the tower base
(c) Ultraviolet/violet lightning
(d) Temporary shut-down of wind turbines
(e) Auditory warning signals
(f) Repowering
All of the mentioned methods report influence on reducing avian collision rates or at least the behavior of birds in flight.
This review found the following three methods to be most effective:
(a) Coloring of rotor blades
(b) Temporary shut-downs of wind turbines
(c) Repowering
The most effective method to reduce avian collision rates at horizontal axis wind turbines is to paint one of the rotor blades black and consequently increasing the visibility of the rotor blades. The presented study reports 71,9 percent reduction of found carcasses of birds at the treated turbines. For this method the effort of implementation is low while the effectiveness is high.
The effectiveness of the found mitigation methods has been proven and they are suited for application. The method of using lightning or sound fields require more testing to determine their effectiveness. Another topic for research could be how different mitigation methods interact with each other. Is there a significant advantage to be had if multiple mitigation methods are applied at the same wind power plant or turbine? Furthermore the environmental impacts of wind turbines are not limited to birds. Other animals like bats are affected too and might require different methods of mitigation.
Despite their important role in our energy system, common wind turbines have some disadvantages. Mainly, those disadvantages are connected to the intermediate conversion of wind energy in rotational energy. The resulting effects include maintenance costs and social acceptance problems. There are different technological approaches, that convert wind energy to electrical energy without its conversion to kinetic energy. As one of those technologies, the electrostatic wind energy conversion is to be discussed in this article. For this discussion, the historical development of this technology is presented. There are three important projects which will be presented to explain the technology and its different technological approaches. Those projects are the WPG, the EWICON and the SWET. Furthermore the results of those different experimental projects are collected and analyzed. On the basis of this analysis it is discussed, whether or not the electrostatic wind energy conversion could be of importance in a future energy system. Therefore the technology is set in relation to modern wind turbines. Also, important factors that influence the efficiency and energy output of those systems are outlined for further research. Due to different technological approaches a suggestion is made for the most promising system setting.
Self-build small wind turbines are used for rural electrification in the developed and developing world as well as for educational purposes. To give an overview about self-build small wind turbines a systematic literature review was conducted. The identified literature deals with two different vertical and horizontal axis turbine designs. The vertical axis turbines are both prototypes while one of the horizontal axis designs, the design by Piggott is widely used in rural electrification projects. Different papers dealing with the optimization of the Piggott design exist. In retrospect the conduction of a holistic review was not possible due to limited resources and length of this review. Nevertheless it can give a quick overview and a starting point for further research.
There are many hydropower turbines for low heads or low flows on a small scale. Many technologies are unsuitable for developing countries because equipment or materials are limited, high-tech machines are to expensive or spare parts are not readily available. This review combines currently available technologies with the requirements of developing countries in small, micro and pico hydropower. In small hydropower a propeller turbine from Thailand has a high efficiency of 70 to 80 percent at calculated production costs of around $ 513 per kW. Pumps as turbines are suitable for developing countries in micro hydropower due to readily availability, low price and an large number of standard sizes. In pico-scale, a low-cost Turgo wheel can be made of spoons for $ 48 and yields acceptable values in comparison to a 3D printed Pelton wheel for $ 822. While the Turgo wheel is suitable for high heads, a homemade siphon turbine can be used for low heads. The siphon turbine generates up to 200 W, is made of materials that are available anywhere in the world, and costs less than $ 50.
The first oscillating water column was invented in 1940. In the past decades the need of wave energy systems has significantly increased. This article quickly describes the Wells turbine and possibilities to enhance its performance and should answer the question: what are the design parameters that can be optimized?
Furthermore it gives a small outlook about the history of oscillating Water Columns.
The impact of hydro-power plants on the ecosystem was studied with focus on the fish mortality and types of damage for many years. The fish mortality have a wide range of causes. Types of damage can be different and are caused by different parts of the power plant. The most dangerous part of the system are the fast moving turbine blades. They can cause blade strike and barotrauma due to the high speeds. Different types of turbines were developed for a better survival rate. Five different types of different research groups and manufacturers are presented in this paper. By considering those newly developed turbine designs, a fish survival rate from 96 % to 100 % is achieved.
The global salinity gradient power (SGP) potential is between 1650 - 2000 TWH/a and can be converted by mixing two solutions with different salinities. The harnessing of SGP for conversion into power can be accomplished by means of pressure retarded osmosis (PRO) and reverse electrodialysis (RED). PRO and RED are membrane-based technologies and have different working principles. PRO uses a semipermeable membrane to seperate a concentrated salt solution from a diluted solution. The diluted solution flows through the semipermeable membrane towards the concentrated solution, which increases the pressure within the concentrated solution chamber. The pressure is balanced by a turbine and electricity is generated. RED uses the transport of ions through cation and anion exchange membranes. The chambers between the membranes are alternately filled with a concentrated and diluted solution. The salinity gradient difference is the driving force in transporting ions that results in an electric potential, which is then converted to electricity. The comparison shows that there are two different fields of application for PRO and RED. PRO is especially suitable at extracting salinity energy from large concentration differences. In contrast, RED are not effect by increasing concentration differences. So PRO are supposed to focus on applications with brines or waste water and RED on applications with river water and seawater. Moreover, just a few measured values from processes under real conditions are available, which makes it difficult to compare PRO and RED.
The EGU Journal of Renewable Energy Short Reviews (EGUJRenEnRev) is a teaching project rather that a regular scientific journal. To publish in this journal, it is a premise to take part in the master course wind power, hydro power and biomass usage at the faculty of Energy, Building Services and Environmental Engineering of the Münster University of Applied Sciences.
Students receive an equivalent of 2.5 credit points (European Credit Transfer and Accumulation System - ECTS) for their engagement in the course and for publishing a short review article of at most 3000 words in this periodical. The publication process closely mimics the typical publication procedure of a regular journal. The peer-review process, however, is conducted within the group of course-participants.
Although being just an exercise, we think that publishing the outcome of this course in a citable manner is not only promoting the motivation of our students, but may also be a helpful source of introductory information for researchers and practitioners in the field of renewable energies. We encourage students to write their articles in English, but this is not mandatory. The reader will thus find a few articles in German language. To further encourage students practicing English writing, perfect grammar is not part of the assessment.
We especially thank our students for working with LaTeX on Overleaf, although LaTeX is new to some of them. In this way, the editorial workload was reduced to a minimum. We also thank our students for sharing their work under the creative commons attribution licence (CC-BY). I appreciate their contribution to scientific information, being available to every person of the world, almost without barriers. I also thank the corresponding authors and publishers of the cited work, for granting permission to reuse graphics free of charge. All other figures had to be replaced or removed prior to publication.
With floating offshore wind turbines, new sources of wind energy can be used, which cannot be tapped into by bottom-fixed wind turbine systems. However, due to their design, they experience additional motion caused by wind and wave loads. The motions that are induced into the system have an oscillating course. This affects the aerodynamic properties of the wind turbine and leads to changes in the thrust force and power output of floating wind turbines compared to bottom-fixed wind turbines. Furthermore, the motions lead to an earlier breakdown of the helical wake structure behind the wind turbine and moreover lead to a decreased reliability of the rotor blades. Differences in the effects of wind and wave loads on the aerodynamic performance of floating offshore wind turbines supported by different platform systems were found.
Originally this article was supposed to be a comparison between the technological differences of bottom-fixed offshore wind turbines (BOWT) and floating offshore wind turbines (FOWT). However, several authors already contributed to this topic and came to the conclusion that the higher levelized costs of energy (LCOE) prevent FOWTs from successfully entering the energy market. Multiple sources seem to agree on this conclusion but often do not provide the reader with further information regarding the LCOE. This is the reason why this article understands itself as an in depth cost comparison between BOWTs and FOWTs. For this purpose, individual LCOE are calculated for the upcoming FOWT technologies such as spar-buoy (SPAR), tension-leg platform (TLP) and semi-submersible platform (semi-sub) as well as conventional BOWTs using the wind turbines hours of full utilization (HOFU). The resulting functions are visualized graphically in order to determine break-even points between BOWTs and FOWTs. Finally, a sensitivity analysis is carried out to determine the influence of the weighted average costs of capital (WACC).
Die Hälfte des Endenergiebedarfs in Deutschland wird zur Deckung des Wärmebedarfs der Wirtschaft und der privaten Haushalte benötigt; überwiegend erzeugt durch Erdgas und Heizöl. Gerade die energetisch nur unzureichend sanierten Einfamilienhausbestände des ländlichen Raumes bergen ein hohes Potenzial für Energieeinsparungs- und Effizienzsstrategien, um zum einen den Klimaschutz zu fördern und zum anderen eine nachhaltige wirtschaftliche Entwicklung des ländlichen Raumes anzustoßen. Die 9. Steinfurter Bioenergiefachtagung zeigt Strategien und Maßnahmen auf, die zeigen, wie eine "Wärmewende im ländlichen Raum" aussehen kann, welche Chancen und Möglichkeiten sie bietet und warum eine "Wärmewende" strategisch unabdingbar für das Gelingen des Generationenprojektes "Energiewende" insgesamt ist. Die Veranstaltung zeichnet den Pfad von konzeptionellen Ideen über Beispiele aus der Praxis bis hin zu zukunftsweisenden technologischen Ansätzen: Wärmekataster Kreis Steinfurt KWK-Modellkommune Saerbeck Wege zum Bioenergiedorf - Praxisbeispiele Technische Voraussetzungen und Möglichkeiten für effiziente Wärmenetze im ländlichen Raum Finanzierungs- und Fördermodelle für eine gelungene Wärmewende
Mit wenigen Ausnahmen wird im elektrischen Versorgungssystem die Pumpspeichertechnik zur Pufferung größerer Abweichungen zwischen momentanem Stromverbrauch und -erzeugung und zur zeitlichen Verschiebung von Lasten eingesetzt. Erste großtechnische Anlagen wurden bereits Ende der zwanziger Jahre des letzten Jahrhunderts in Deutschland gebaut, um die Auslastung thermischer Kraftwerke gleichmäßiger zu ermöglichen. Pumpspeicherwerke bieten sich somit als Referenztechnologie an, mit der sich neue Entwicklungen messen müssen. Ein Überblick.
Das Forschungsprojekt "Verringerung von Lebensmittelabfällen - Identifikation von Ursachen und Handlungsoptionen in Nordrhein-Westfalen" (Zeitrahmen: 9/2011 - 2/2012) im Auftrag des Ministeriums für Klimaschutz, Umwelt, Landwirtschaft, Natur- und Verbraucherschutz in Nordrhein-Westfalen (MKULNV) steht im Kontext der Diskussion um eine neue Wertschätzung für Lebensmittel und einen nachhaltigen Lebensstil. Das Institut für nachhaltige Ernährung und Ernährungswirtschaft (iSuN) der Fachhochschule Münster wurde gemeinsam mit der Verbraucherzentrale Nordrhein-Westfalen beauftragt, die Studie mit dem Schwerpunkt der Identifikation von Ursachen und Handlungsoptionen zur Verringerung von Lebensmittelabfällen in Nordrhein-Westfalen durchzuführen. Der Lebensmittelmarkt ist stark arbeitsteilig organisiert und global vernetzt. Die Situation in Nordrhein-Westfalen unterscheidet sich dabei nicht wesentlich von der in ganz Deutschland oder in Europa. Die Orientierung auf Nordrhein-Westfalen erfolgte über die Auswahl von Interwiepartnern und Unternehmensexperten sowie über die Auswahl der für Nordrhein-Westfalen besonders relevanten Produktgruppen Gemüse, Brot und Backwaren, Milch und Milchprodukte sowie Fleisch und Wurstwaren. Handlungsoptionen zur Verringerung von Lebensmittelabfällen in Nordrhein-Westfalen sind prinzipiell auf andere Bundesländer in Deutschland übertragbar. Die Studie setzt sich aus insgesamt vier Forschungsbausteinen zusammen. Im Forschungsbaustein A werden die Ursachen von Lebensmittelabfällen für die vier relevanten Produktgruppen analysiert und Handlungsempfehlungen zur Reduzierung von Lebensmittelabfällen abgeleitet. Betrachtet werden die jeweiligen Wertschöpfungsketten von der Landwirtschaft bis zum Handel. Die analysierten Ursachenfelder zeigen stufenübergreifende Wirkungen innerhalb der Wertschöpfungskette, die zu Lebensmittelabfall führen. Aus diesem Grunde ist besonders die Betrachtung der Schnittstellen für die Entwicklung von Maßnahmen entscheidend. Forschungsbaustein B untersucht auf der Grundlage persönlicher Interviews und anonymer Onlineinterviews Ursachen, die Verbraucherinnen und Verbraucher veranlassen, Lebensmittel wegzuwerfen und leitet daraus Empfehlungen zur Verringerung von Lebensmittelabfällen ab. Die Befragungen zeigen, dass insbesondere komplexe, oft schlecht planbare Lebens- und Arbeitssituationen dazu führen, dass Lebensmittel weggeworfen werden müssen. Forschungsbaustein C analysiert statistisch verfügbare Daten, aus denen sich Lebensmittelabfallmengen für Nordrhein-Westfalen hochrechnen lassen. Forschungsbaustein D zeigt auf, dass die Entstehung von Lebensmittelabfällen nennenswerte soziale, ökonomische und ökologische Wirkungen nach sich zieht, die zu beachten sind. Mit der modellhaften Betrachtung der Ressourcenverbräuche und Umweltbelastungen ausgewählter Lebensmittel werden die Dimensionen der ökologischen Wirkung von Lebensmittelabfällen deutlich gemacht. Die Ressourcenverbräuche in den Vorketten der Lebensmittel betragen ein Vielfaches des Abfallaufkommens. Die ökologischen Fußabdrücke von Lebensmitteln der vier Produktgruppen verteilen sich anders als das Abfallaufkommen, da den verschiedenen Lebensmitteln unterschiedliche Ressourcenverbräuche zugeordnet sind. Bei den Lebensmittelabfällen hat die Produktgruppe Obst und Gemüse mengenmäßig den größten Anteil, dafür aber einen deutlich geringeren Anteil an den Ressourcenverbräuchen als Fleischprodukte. Aus dem Kontext der vier Forschungsbausteine leitet die Studie Handlungsvorschläge zur Verringerung und Vermeidung der Lebensmittelabfälle in Nordrhein-Westfalen in den vier grundlegenden Kategorien "Prozessoptimierung/Schnittstellenmanagement", "Strukturen und Regeln", "Verwerten statt Entwerten" sowie "Wertschätzen und Aufwerten" ab. Anhand dieser Handlungsfelder können konkrete Ansätze für die Teilnehmer des Runden Tisches "Neue Wertschätzung für Lebensmittel" aber auch für die Politik in Nordrhein-Westfalen abgeleitet werden, um Lebensmittelabfälle zu vermeiden und "neue Märkte" zur Reduzierung von Warenverlusten bzw. Weiterverwendung von Lebensmittelabfällen zu identifizieren.
Auf Basis der Wirtschaftschulen und der Technischen Schulen des Kreises Steinfurt wurde im Laufe des Forschungsprojektes ein Konzept zur integralen Sanierung von Schulen erarbeitet. Zu Beginn des Projektes wurde eine umfangreiche Bestandsaufnahme der betrachteten Schulen vorgenommen. Hierzu erfolgten messtechnische Untersuchungen in ausgewählten Räumen der Schulen als auch Befragungen der am Schulbetrieb beteiligten Gruppen. Die messtechnischen Untersuchungen umfassten die Raumluftsituation, die Raumtemperatur, die Akustik und die Beleuchtungssituation. Mittels Fragebogen wurde das subjektive Emp-finden der Schüler und Lehrkräfte bezüglich der Raumluft, Akustik, Beleuchtung und Behag-lichkeit erfasst. (Abschnitt 1.1.6, S. 14 und Abschnitt 1.3 bis 1.5, ab S. 33) Die Raumtemperaturen, die Akustik und die Beleuchtungssituation zeigten sich sowohl bei den Messungen als auch in den Befragungen überwiegend als nicht auffällig. Eine gravieren-de Ausnahme hiervon stellten die Raumtemperaturen in den EDV-Räumen der Wirtschaft-schulen dar. Die inneren Wärmelasten durch den Betrieb der Computer lassen die Tempera-tur in den Räumen im Sommer auf unerträgliche Temperaturen ansteigen. Im Rahmen des Projektes wurde daher in einem EDV-Raum die Wirksamkeit einer Kühldecke und einer Schwerkraftkühlung messtechnisch untersucht. Beide Kühlsysteme wurden mittels Kühlwas-ser aus Erdsonden betrieben und waren in der Lage, die Temperatur im EDV-Raum im akzeptablen Bereich zu halten. (Kapitel 5, S. 143) Im Hinblick auf die Überhitzung der Räume und den Stromverbrauch von Computern als Ein-zelplatzlösung wurden die Vorteile des Green-IT bezüglich der Behaglichkeit, des Stromver-brauchs und der Wirtschaftlichkeit im Zusammenhang mit Schulen herausgestellt. (Abschnitt 6.2.1, S. 187) Die Raumluftsituation stellte sich in fast allen untersuchten Situationen als mangelhaft her-aus. Das Ergebnis bestätigt Untersuchungsergebnisse anderer Institutionen im In- und Aus-land und verlangt einen Paradigmenwechsel bezüglich der Belüftung von Schulräumen. Wei-tergehende messtechnische Untersuchungen an einem Proberaum der Technischen Schulen zeigten, dass auch die Lüftung über gekippte Fenster unzureichend ist (Abschnitt 1.3.5, S. 44 bzw. Abschnitt 6.2.5, S. 200). Alles in allem ist bei normaler Personenzahl in einem Klassen-raum eine mechanische Lüftung unerlässlich. In den Technischen Schulen werden diese Er-kenntnisse durch den Einbau von lüftungstechnischen Anlagen umgesetzt. Nach Abschluss von Sanierungsmaßnahmen an den Wirtschaftsschulen wurden erneut akus-tische Messungen in Klassenräumen durchgeführt. Es zeigte sich, dass die vor der Sanierung guten Ergebnisse sich durch akustisch wirksame Wandpaneele erneut einhalten lassen. Das Ergebnis bestätigt, dass pflegeleichte, schallharte Böden in Kombination mit durchdachten akustischen Maßnahmen problemlos funktionieren. Die energetische Sanierung von Gebäuden setzt einen bekannten Ist-Zustand des spezifischen Energieverbrauchs voraus, um Zielstellungen für die durch die Sanierung zu erwartenden Einsparungen formulieren zu können. Erhebungen bei den kommunalen Schulträgern sollten dazu dienen, diesen Ist-Zustand der Schulen zu beschreiben und den energetischen Erfolg bereits durchgeführter Sanierungen zu dokumentieren. Es stellte sich heraus, dass die Dokumentation der entsprechenden Daten bei den Schulträgern in den überwiegenden Fäl-len nicht vorliegen und auch nicht bereitgestellt werden können. Wesentliche Ursachen hier-für sind die Personalsituation und fehlendes Energiemanagement in den Verwaltungen. Der im Arbeitsplan vorgesehenen Erstellung einer Datenbank zu Sanierungsauswirkungen auf den Energieverbrauch von Schulen fehlte damit die Basis. Die zeitliche Entwicklung der spezifischen Energieverbräuche konnte für einige Schulen zusammengetragen werden. (Ab-schnitt 1.2, S. 23; Kapitel 1, S. 85 und Kapitel 3, S. 103) Die Erstellung des Sanierungskonzeptes für die Wirtschaftsschulen war zu Projektbeginn be-reits erfolgt. Im Rahmen des Projektes wurden die anstehenden und darüber hinausgehen-den Sanierungsschritte mittels dynamischer Simulationsrechnungen hinsichtlich ihrer ener-getischen Auswirkungen beurteilt und wirtschaftlich bewertet. Darüber hinaus konnten mit der dynamischen Simulationsrechnung Energieeinsparpotenziale aufgezeigt werden, die mit-tels Optimierung der Betriebstechnik erreicht werden können. (Abschnitt 6.1.4, S. 168) Im Rahmen des Sanierungskonzeptes der Technischen Schulen wurde für die Frischluftzufuhr und Temperierung der Klassenräume nach einem kombinierten, alternativen System ge-sucht. Daraus entwickelte sich die Klimawand. Diese benötigt aufgrund der flächigen Ausfüh-rung in Verbindung mit unterstützenden Konvektionsströmungen in Konvektionsschächten zur Temperierung nur geringe Über- bzw. Untertemperaturen. Gleichzeitig wird die Klimawand für die Frischluftzufuhr mit einem zentralen Belüftungssystem kombiniert. Die Klimawand ist unauffällig, robust mit geringem Platzbedarf und ist somit weitestgehend aus dem Wirkungsbereich der Schüler ausgenommen. (Abschnitt 6.2.3, S. 192) Das Sanierungskonzept der Technischen Schulen wurde im Rahmen des Projektes erstellt. Die jetzt beginnende bautechnische Umsetzung des Konzeptes beinhaltet die wesentlichen Ergebnisse des Projektes. Der Einbau von lüftungstechnischen Anlagen sowie die mittels dy-namischer Simulation erarbeitete bauphysikalische Optimierung sind Ergebnisse der Projekt-arbeit. Die dynamische Simulation hat sich als starkes und wichtiges Werkzeug bezüglich der Erstellung von Sanierungskonzepten erwiesen (Abschnitt 6.1.2, S. 157 und Abschnitt 6.1.4, S. 168). Durch die Sanierung wird der spezifische Primärenergiebedarf der Technischen Schulen von 73 auf rund 25 kWh pro Quadratmeter und Jahr sinken.