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An Early Stage Innovation for Floating Offshore Wind Applications
Offshore wind turbines are immense and mechanically complex. Their energy is also relatively expensive. Electrohydrodynamic (EHD) wind energy is a new way to produce power by converting the kinetic energy of offshore winds into electricity with mechanical simplicity. It could dramatically reduce the cost of offshore wind energy generation and increase capacity factors to well over 50%, enabling faster growth of this renewable power capacity worldwide. A recent US$ 4.9 million award from ARPA-E is funding a collaboration between small company innovator Accio Energy Inc. and the University of Maine’s Advanced Structures and Composites Center to design, build and test the first sub-scale prototype off the coast of Maine, as well as to validate a transformative LCOE model of a full-scale design.
By Jennifer Baird, CEO, and Dawn White, President and CTO, Accio Energy, USA
Accio Energy’s innovative approach to offshore wind energy harvesting could create a new, lower-cost offshore wind option to accelerate development of the US and global offshore wind market, helping to mitigate the impact of greenhouse gas emissions and climate change risks.
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Becoming Flight Ready with the Latest UAV Systems
Natural Power is an independent renewable energy consultancy renowned for early adoption of successful technologies. Understanding complex environments and engineering challenges is the focus of a large number of renewable energy experts who make up this organisation. A recent investment has been made into aerial survey technology to enhance renewable project understanding across all phases of development. This article aims to provide a short review of fixed-wing aerial survey technology, details of equipment, key deliverables, primary benefits and safety controls. There are undoubtedly many unmanned aerial vehicle (UAV) manufacturers and systems available, with technology continually advancing. This review examines Natural Power’s experience in acquiring a Trimble Navigation ‘UX5’ aerial imaging platform.
By Gavin Germaine, Senior Geotechnical Engineer, Natural Power, UK
UAVs, drones and RPAS (remotely piloted aircraft systems) are just a few of the increasing numbers of terms used to describe the rise of latest technology to enter the skies.
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Reducing Wear on Wind Turbines
Deutsche Windtechnik has been measuring wind turbine rotor blades using a laser-based blade angle procedure since 2015. The company has discovered serious shortcomings on some of the 273 Vestas turbines examined to date. Where the relative blade angle deviations were 0.5 of a degree or more, the service technicians corrected the settings. This makes the wind turbines run more quietly, ensures less strain on the material and reduces wear.
By Torsten Wohlert, Deutsche Windtechnik Service, Germany
Deutsche Windtechnik is to carry out measurements on all the wind turbines it maintains as part of a full maintenance contract that includes large components. This year the service provider will be checking the Vestas, NEG Micon and Siemens wind turbines. Similar examination of offshore wind turbines will follow.
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Environmentally Friendly Solutions for Ambitious Technical Tasks
Lubricating oils and greases for offshore wind energy plants have to meet a broad range of special requirements. Among these are not only technical specifications but also rigid environmental standards. This article describes the most severe technical challenges as well as valid environmental requirements, and highlights the very ambitious product development process.
By Martin Wünsch, Head of Research and Development, Lubricant Consult GmbH, Germany
The development and construction of wind energy plants involves numerous technical challenges. A large number of moving components, working temporarily under high stress conditions, have to be well engineered and sufficiently lubricated to prevent them from early failure which would lead to high costs for maintenance and repair, unplanned downtime and production loss. Bearings for the pitch adjustment, for example, rotate very infrequently and are therefore prone to false brinelling and oscillation wear, resulting in damage to the bearing raceways. Thus, the technical demands for lubricants in such applications are extremely high. Moreover, these products, like all chemicals used in the offshore sector, have to meet strict environmental requirements.
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Active Flap Systems Coming Closer to Market
The idea of active flap systems on wind turbine blades is to reduce the variable loading on the blades by continuously adjusting the shape of the trailing edge of the blade to counteract the fluctuating loads from the wind. The reduction in loading means that a larger rotor can be mounted on the same turbine platform and the power production can be increased. In this way the cost of energy (COE) can be reduced, which is the overall goal with the new smart blade control.
By Helge Aagaard Madsen, Research Specialist, DTU Wind Energy, Denmark
Considerable research on active flap systems, or morphing trailing edges of wind turbine blades, has been ongoing for almost 15 years at many wind energy research institutes such as Delft University (the Netherlands), Sandia Laboratories (USA) and DTU (Denmark). At present the different systems are being studied intensively by many European Research Institutes and universities within two ongoing EU funded projects InnWind and AVATAR. The numerical studies show, in general, very promising potentials for load reduction, reaching 40–50% for the different flap systems with the fastest response and with flaps covering a major part of the blade span. The active flap systems will work in parallel with the pitch system, which is the existing method for controlling the loads on the blades. In contrast to the pitch system, which gives the same control action along the whole blade, the flap system is a distributed control system.. It means that different control actions can take place along the blade and this becomes more and more important as the blade size increases. For example, for a 70-metre blade the influence of a gust can be quite different from the tip part to the middle part of the blade. Numerical studies show that pitch and flap systems can work efficiently in parallel giving higher load alleviation than, for example, a cyclic pitch system, and, at the same time, reduce the pitch activity considerably. As pitch bearing wear can be a major challenge for cyclic pitch applications the reduction in pitch activity is an attractive goal.
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Ring-Shaped Bearingless Generator with Buoyant Rotor and Modular Structure
In wind turbines, bearing failures have been a continuing problem and have accounted for a significant proportion of all failures. Bearing-related downtime is among the highest of all components of wind turbines. The location of wind turbines is moving offshore. However, to access offshore sites is difficult and thus wind turbines with high reliability and availability are required. Direct-drive wind generators are argued to have higher reliability and availability than geared generators. However, direct-drive generators require a large diameter, which results in a large mass and high cost, in order to get a high torque rating compared to geared generators. It is disadvantageous in terms of manufacture and maintenance to construct direct-drive generators with a large diameter as a one-body structure. In scaling up the power of direct-drive generators, the structural part becomes dominant in the total mass of the generators. Therefore, it is necessary to find a solution to significantly reduce bearing failures and structural mass, and to facilitate manufacture and maintenance for large direct-drive wind generators.
By Dr Deok-je Bang, Korea Electrotechnology Research Institute, South Korea
In this article, a new generator concept, a ring-shaped bearingless permanent magnet (PM) generator with a buoyant rotor and magnet and core modules, is described as a solution to significantly reduce the bearing failures and the structural mass, and to facilitate manufacture and maintenance for large direct-drive wind turbines.
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AWES Could Potentially Halve Offshore Wind LCOE
UK-based Kite Power Solutions (KPS) is one of a handful of developers of airborne wind 
energy systems (AWES) who are pushing forward a technology to challenge the conventional horizontal axis wind turbines (HAWTs) in the utility-scale offshore market. Floating offshore AWES could potentially halve offshore wind levelised cost of energy (LCOE) compared with HAWTs. In this article, David Ainsworth of KPS explains the challenges in bringing this novel technology to market in the next ten years.
By David Ainsworth, Business Development Director, Kite Power Solutions, UK
Wind is one of the best resources available to combat climate change, but only contributes 1% to world energy needs. Offshore wind is only deployed commercially in Europe and China, with USA and Japanese projects on the horizon. Is this because we cannot afford offshore wind in its current form?
