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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.
Advanced monitoring and control of anaerobic digestion. VAAM-Jahrestagung, Online, Februar 2022
(2022)
Algorithmic Design and Resilience Assessment of Energy Efficient High-Rise Water Supply Systems
(2019)
Anaerobic Fermentation of Organic Material: Biological Processes and Their Control Parameters
(2017)
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.
Biohydrogen production via dark fermentation with pig manure and glucose using pH-dependent feeding
(2020)
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.
Childhood social position and associations between environmental exposures and health outcomes
(2008)
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.
A novel approach for ventilation systems is a periodically varying supply air flow rate, the so-called unsteady mode of operation. So far, useful effects of this unsteady operating mode have been observed, but the effect mechanisms are still unknown. In this manuscript, simulations using the recently proposed k-ω-ζ - f model implemented in a sensitized RANS computational framework for a cuboid room with swirl diffusers are compared and validated with PIV measurements.
Control strategies for optimisation of urban wastewater system based on precipitation forecast
(2001)
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).
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.
Different model structures were compared to simulate the characteristic process variables of the anaerobic digestion of maize, sugar beet and grain silage. Depending on the type and number of the required components, it can be shown that in comparison to the complex Anaerobic Digestion Model No. 1 (ADM1) different simplified model structures can describe the gas production rate, ammonia nitrogen and acetate concentration or pH value equally well. Since the reduction of the predominantly fast kinetics of the methanogenesis, acetogenesis or acidogenesis will only have little effect on the simulation of the specific gas production, it can be proven that the hydrolysis is the rate-limiting step during the uninhibited anaerobic digestion of complex particulate substrates. However, the stoichiometric comparison reveals that the model protein gelatine is not suitable for a representative characterization of agricultural energy crops.
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.
Flexible biogas production can enable demand-oriented energy supply without the need for expensive gas storage expansions, but poses challenges to the stability of the anaerobic digestion (AD) process. In this work, biogas production of laboratory-scale AD of maize silage and sugar beets was optimized to cover the residual load of an electricity self-sufficient community using a simple process model based on first-order kinetics. Experiments show a good agreement between biogas demand, predicted, and measured biogas production. By optimizing biogas conversion schedules based on the measured gas production, a gas storage capacity of 7-8 h was identified for maximum flexibility, which corresponds to typical gas storage sizes at industrial biogas plants in Germany. Various stability indicators were continuously monitored and proved resilient process conditions. These results demonstrate that demand-oriented biogas production using model predictive control is a promising approach to enable existing biogas plants to provide balancing energy.
The development of compact treatment devices with high removal efficiencies and low space requirements is a key objective of urban stormwater
treatment. Thus, many devices utilize a combination of sedimentation and upward flow filtration in a single system. This study, for the
first time, evaluates the flow field inside a combined filter-lamella separator via computational fluid dynamics. Herein, three objectives
are investigated: (i) the flow field for different structural configurations, (ii) the distribution of particulate matter along the filter bed and
(iii) the dynamic clogging in discrete filter zones, which is addressed by a clogging model derived from literature data. The results indicate
that a direct combination of a filtration stage with a lamella separator promotes a uniform flow distribution. The distribution of particulate
matter along the filter bed varies with configuration and particle size. Clogging, induced by particles in the spectrum ,63 μm, creates
gradients of hydraulic conductivity along the filter bed. After treating about half of Germany’s annual runoff-efficient precipitation at a rainfall
intensity of 5 L/(s·ha), the filtration rates increase in the front of the filter bed by þ10%. Thus, long-term operating behavior is sensitive to
efficient filter utilization in compact treatment devices.
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 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.
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 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.
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.
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.
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.
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.
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.
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.