TY - RPRT A1 - Budde, Janik T1 - A comparison of reverse electrodialysis and pressure retarded osmosis as technologies for salinity gradient power N2 - 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. T3 - EGU Master Journal of Renewable Energy Short Reviews - 2021_14 KW - osmotic power KW - salinity gradient power KW - salinity gradient energy KW - blue energy KW - pressure retarded osmosis Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:836-opus-136882 ER - TY - RPRT A1 - Hinse, Michael T1 - The Wells turbine: state of the art N2 - 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. T3 - EGU Master Journal of Renewable Energy Short Reviews - 2021_12 KW - wells turbine KW - owc KW - energy KW - oscillating water column KW - optimization Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:836-opus-136861 ER - TY - RPRT A1 - Hoge, Alexander T1 - Measures for mitigating avian collision rates with wind turbines - Determining an effective technique regarding effort and effect N2 - 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. T3 - EGU Master Journal of Renewable Energy Short Reviews - 2021_08 KW - wind turbine KW - wind energy KW - birds KW - collisions KW - mitigation Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:836-opus-136826 ER - TY - RPRT A1 - Linnenschmidt, Jan-Niklas T1 - Cost comparison between bottom-fixed and floating offshore wind turbines - Calculating LCOE based on full hours of utilization and corresponding break-even points N2 - 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). T3 - EGU Master Journal of Renewable Energy Short Reviews - 2021_02 KW - cost comparison KW - bottom-fixed KW - floating KW - offshore wind turbines KW - LCOE Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:836-opus-136764 ER - TY - RPRT A1 - Olbertz, Niklas T1 - Sustainable hydro-power plants with focus on fish-friendly turbine design N2 - 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. T3 - EGU Master Journal of Renewable Energy Short Reviews - 2021_13 KW - fish-friendly turbine KW - fish injury KW - sustainable hydro-power KW - Alden turbine KW - Minimum Gap Runner Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:836-opus-136876 ER - TY - RPRT A1 - Scheffler, Mark T1 - Low-Cost Hydropower Turbines for Developing Countries N2 - 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. T3 - EGU Master Journal of Renewable Energy Short Reviews - 2021_11 KW - hydropower KW - developing countries KW - low-cost KW - micro hydro KW - small hydro Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:836-opus-136858 ER - TY - RPRT A1 - Schmeinck, Hendrik T1 - Impact of wind and wave induced platform motion on the aerodynamic properties of floating offshore wind turbines N2 - 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. T3 - EGU Master Journal of Renewable Energy Short Reviews - 2021_01 KW - floating offshore wind turbine KW - unsteady aerodynamics KW - six-degree-of-freedom motions KW - failure probabilities KW - rotor blade reliability Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:836-opus-136750 ER - TY - RPRT A1 - Speller, Julian T1 - Self-build small wind turbines - A review N2 - 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. T3 - EGU Master Journal of Renewable Energy Short Reviews - 2021_10 KW - small wind turbines KW - self-build KW - horizontal axis KW - vertical axis Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:836-opus-136845 ER - TY - RPRT A1 - Steinigeweg, Joshua T1 - Review of the suitability of thermoplastic rotor blades in terms of the circular economy N2 - 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. T3 - EGU Master Journal of Renewable Energy Short Reviews - 2021_06 KW - Wind power KW - Recycling KW - Thermoplastic rotor KW - Solvolysis KW - Circular economy Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:836-opus-136809 ER - TY - RPRT A1 - Tchorz, Enno T1 - Sensorless maximum power point tracking systems in wind energy conversion systems - A review N2 - 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. T3 - EGU Master Journal of Renewable Energy Short Reviews - 2021_05 Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:836-opus-136791 ER -