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- Category: Articles
A Monolithic Concrete Platform for Floating Offshore Wind Turbines
A novel concept of a floating platform for supporting wind turbines (named WindCrete) has been developed at the Universitat Politècnica de Catalunya (UPC) in order to substantially reduce the capital expenditure or CAPEX for floating offshore wind turbines. The concept is based on a monolithic full concrete structure, including the tower and the floater, which also allows a significant reduction of the operating expense, or OPEX. The basics of the concept are presented in this article, including the advantages of concrete in the marine environment, the main dimensions and the hydrostatic and hydrodynamic properties of WindCrete.
By Climent Molins and Alexis Campos, Universitat Politècnica de Catalunya, Spain
- Category: Articles
Effective Reduction Using a Low-Speed Coupling Made of Advanced Composites
Poor drive-train reliability is still one of the main hurdles to get over in order to achieve a more competitive cost for wind energy. Many surveys confirm that gearbox failure rates are moderate compared to other components but, once a failure occurs, it leads to the highest downtime and a considerable loss of energy production. According to the results of investigations carried out by GL Garrad Hassan regarding the relative cost of energy, the reduction of gearbox failures rates by 50% would save revenue losses by almost 40% compared to the initial capital cost of the gearbox. Joint investigations by the National Renewable Energy Laboratory (NREL) and Alstom, with the target of improved drive-train reliability, have shown that non-torque loads (bending moments) can significantly affect the reliability of the gearbox. Non-torque loads are caused by aerodynamic loads, rotor overhung weight and drive-train weight, and occur independently of the drive-train concept. Low-speed couplings are pictured as a potential remedy for new drive-train layouts to solve the problem ‘outside the gearbox’.
By Alexander Kari, Geislinger GmbH, Austria
- Category: Articles
Could It Change the Game for Renewables?
What if reliable and cheap wind energy could be generated, stored and distributed straight out of a box? EnerKíte GmbH from Germany has developed a novel technology to harness the stronger and steadier winds at higher altitudes. At average to fair onshore wind conditions the kite-based wind power plants – or airborne wind energy converters – allow for capacity factors way above 70% while aiming to keep the cost of electricity below 5 euro-cents per kilowatt-hour. The combination of stronger winds at higher altitudes and the low design wind speeds of 7.5m/s enable capacity factors higher than offshore power plants at a lower cost. Distributed generation, storage and hybridisation with other renewables could all help towards 100% renewable scenarios.
By Alexander Bormann, CEO, EnerKite, Germany
- Category: Articles
Getting Ready for the Future
Within a few years there are not likely to be many places in the world with traditional mega or micro electricity grids. As use of renewables such as wind and especially photovoltaics increases, sometimes to more than 100%, and the energy supplies are linked to grids worldwide, there will be a need to add storage and smart control systems to enable switches between renewable energies and other fuels such as diesel. However, most traditionally manufactured small and medium wind turbines cannot cope with smart grids.
By Frits Ogg, Renewable Energy Consultant, The Netherlands
- Category: Articles
Anemometry Technology to Measure the Wind in Front of the Rotor
The ROMO Wind iSpin system uses proven ultrasonic technology to measure wind where it first hits the turbine – directly at the spinner. In this way, it is able to measure parameters at the nacelle which until now have been difficult or impossible to measure accurately. Operators gather exact information on the wind conditions in front of the rotor including wind speed, yaw alignment, flow inclination, turbulence, rotor position and temperature. This enables them to check whether their turbines are aligned for the best possible yield. At the same time, the data allows for optimised wind farm management and load reduction, which prolongs the total life of the turbines.
By Harald Hohlen, ROMO Wind Deutschland GmbH, Germany
- Category: Articles
The Integrated Urban Green Wind Energy Solution
PowerNEST is a new sustainable energy generation system for the tops of buildings. IBIS Power and Pontis Engineering have joined forces to get PowerNEST to a state where it is ready to enter the European market. The consortium has received a Horizon 2020 SME Phase II grant from the EC and is now fully operational and ready to realise the first demonstration in the Netherlands within a few months. The initial stage of the overall European project consists of installing 25 units within 2 years, therefore gaining sufficient knowledge to develop a standardised mass production design and establish a distribution network. The EU independent review committee awarded a score of 14.35 out of 15.00 to the project with all aspects graded as ‘excellent’.
By Anna Blanch Vergés and Dr Alexander B. Suma, IBIS Power, The Netherlands
- Category: Articles
A Few Potential Design Alternatives and System-level Reassessment
In recent years, increasing evidence of failures has been reported from spherical roller main bearings used in three-point mounting (TPM) drivetrains of wind turbines. One of the leading causes has been micropitting, a failure mode that is possibly overlooked by design, selection and life-prediction tools. It remains to be seen if retrofitting problematic spherical roller bearings (SRBs) with improved bearing design solutions can improve their durability. Questions to ask might be: ‘Are the operating conditions of the main bearing well understood?’ and ‘Are the failures caused by deficient design practice or other unidentified external sources within the system?’ These questions fundamentally challenge the underlying design basis and encourage the need for a system analysis approach that is currently being undertaken by researchers from the National Renewable Energy Laboratory (NREL). Specifically, this article discusses a few potential design alternatives and system-level reassessment to circumvent micropitting in main bearings used in TPM drivetrains.
By Latha Sethuraman, Yi Guo and Shuangwen Sheng, National Wind Technology Center, National Renewable Energy Laboratory, USA
