Wind assessment for micro wind turbines in an urban environment

Wind flow in urban environments could be seen as a potential source of energy. This form of energy could be exploited by means of micro wind turbines placed along the existing infrastructures. To test this, an outdoor campaign was organised, which recorded the wind characteristics at different locations around a highway noise barrier in Delft, the Netherlands. The real-time data set was validated with a two-dimensional Computational Fluid Dynamics study. Both the influence of the high turbulence and the inflow angle on the positioning of the micro wind turbines are assessed for the case of perpendicular flow towards the plane of the noise barrier. Results indicated that integrating micro wind turbines with the noise barriers proves advantageous due to the flow velocity increment downstream. Lastly, a noise assessment was conducted in order to determine the optimal spacing between micro wind turbines, which impacts its social acceptance

New System for the Acceleration of the Airflow in Wind Turbines

Background: This patent is based on the wind industry technology called Diffuser Augmented Wind Turbines (DAWTs). This technology consists of a horizontal axis wind turbine, which is housed inside a duct with diverging section in the direction of the free air stream. In this paper, a review of preceding patents related to this technology is carried out. Objective: This paper presents an innovative patent to improve the performance of horizontal axis wind turbines. In particular, this system is aimed at improving the performance of those turbines that otherwise might not be installed due to the low wind resource existing at certain locations. Methods: The most innovative elements of this patent are: (1) the semi-spherical grooves, which are mechanized on the surface of the two diffusers in order to guarantee a more energetic boundary layer; (2) the coaxial diffuser, which is located downwind following the first diffuser in order to increase the suction effect on the air mass close to the inlet; (3) the coaxial rings located around the first diffuser outlet, which are used to deflect the external airflow toward the turbine wake; and (4), the selforientating system to orientate the system by the prevailing wind direction. Results: An application of the patent for increasing the power generated by a horizontal axis wind turbine with three blades is presented. The patent is designed and its performance is evaluated by using a Computational Fluid Dynamics code. The numerical results show that this system rises the airflow going through the rotor of the turbine. Conclusion: The patented device is an original contribution aimed at enabling a more profitable installation of wind turbines in places where the wind resource is insufficient because of the wind shear caused both by the proximity of the earth and the obstacles on the earth surface.This work was supported by the OASIS Research Project that was cofinanced by CDTI (Spanish Science and Innovation Ministry) and developed with the Spanish companies: Iridium, OHL Concesiones, Abertis, Sice, Indra, Dragados, OHL, Geocisa, GMV, Asfaltos Augusta, Hidrofersa, Eipsa, PyG, CPS, AEC and Torre de Comares Arquitectos S.L and 16 research centres. The authors also acknowledge the partial funding with FEDER funds under the Research Project FC-15-GRUPIN14-004. Finally, we also thank Swanson Analysis Inc. for the use of ANSYS University Research programs as well as the Workbench simulation environment

The conceptual design of a safety system: For the 5MW Deepwind wind turbine

This research work proposes the initial design considerations of the safety system of the Deepwind offshore floating vertical axis wind turbine. Deepwind is a wind turbine model and prototype development project under the umbrella of the 7th European Framework Programme. The safety system is one of the aspects of this project and it is dealt within this Thesis work. Safety is one of the most important features that modern wind turbines should include. Statistics and industrial experience have indicated to the regulation organizations (e.g. IEC,DNV) to add safety systems in the complex electromechanical system of a wind turbine. The most crucial safety feature is the over-speeding control. Usually the controller functions alleviate this problem but an additional safety level is more than necessary to avoid irreparable incidents. This safety feature has been developed within the scope of this Thesis. Therefore, the major task is the definition and design of the safety system functions. This task was conducted in the context of the Conceptual Design method. Several possibilities were investigated. This search led to systems using the aerodynamic and hydrodynamic principles of operation. Many aspects were taken into account concerning the functionality and compatibility of these safety systems. These aspects were addressed from literature review and generation of engineering models in MATLAB. Finally, through multi-criteria analysis, which is one of the tools of Conceptual Design, all the systems were compared and a solution was formulated with the initial design configurations for further development. The proposal of this Master Thesis is to sink the wind turbine system inside the sea, by adding seawater into the spar buoy in an effective time response. Consequently, the blades of the wind turbine hit the seawater and thus create enough drag forces to reduce effectively the rotational speed. The particular wind turbine characteristics make this solution the most promising, as presented through the whole process. This report proposes the initial design characteristics but also suggests further steps on the design process of the safety system.Aerospace EngineeringSustainable Energy Technolog

On-site wind powered hydrogen refuelling stations: From national level to a case study in Germany

Hydrogen refueling stations are an important part of the infrastructural development that should be developed in order to realize a 100% sustainable economy for the future. Most of the refueling stations are located within urban areas but there are many located outside urban areas or in remote areas. Hydrogen could either be transported to these sites or being locally produced with integrated sustainable energy systems. In this study the potential number for wind powered hydrogen refueling stations using GIS is determined. Furthermore the amount of hydrogen that could be produced and used is determined via energy system simulation. Finally the hydrogen production and dispensing costs are calculated.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Energy Technolog

Performance characteristics of a micro wind turbine integrated on a noise barrier

tract Micro wind turbines can be structurally integrated on top of the solid base of noise barriers near highways. A number of performance factors were assessed with holistic experiments in wind tunnel and in the field. The wind turbines underperformed when exposed in yawed flow conditions. The theoretical cosθ theories for yaw misalignment did not always predict power correctly. Inverter losses turned out to be crucial especially in standby mode. Combination of standby losses with yawed flow losses and low wind speed regime may even result in a net power consuming turbine. The micro wind turbine control system for maintaining optimal power production underperformed in the field when comparing tip speed ratios and performance coefficients with the values recorded in the wind tunnel. The turbine was idling between 20%–30% of time as it was assessed for sites with annual average wind speeds of three to five meters per second without any power production. Finally, the field test analysis showed that inadequate yaw response could potentially lead to 18% of the losses, the inverter related losses to 8%, and control related losses to 33%. The totalized loss led to a 48% efficiency drop when compared with the ideal power production measured before the inverter. Micro wind turbine’s performance has room for optimization for application in turbulent wind conditions on top of noise barriers. https://doi.org/10.3390/en1405128

Technical potential of on-site wind powered hydrogen producing refuelling stations in the Netherlands

This study assesses the technical potential of wind turbines to be installed next to existing fuelling stations in order to produce hydrogen. Hydrogen will be used for Fuel Cell Vehicle refuelling and feed-in existing local gas grids. The suitable fuelling stations are selected through a GIS assessment applying buffer zones and taking into account risks associated with wind turbine installation next to built-up areas, critical infrastructures and ecological networks. It was found that 4.6% of existing fuelling stations are suitable. Further, a hydrogen production potential assessment was made using weather station datasets, land cover data and was expressed as potential future Fuel Cell Electric Vehicle demand coverage. It was found that for a 30% FCEV drivetrain scenario, these stations can produce 2.3% of this demand. Finally, a case study was made for the proximity of those stations in existing gas distribution grids.Energy Technolog

On-site wind powered hydrogen refuelling stations: From national level to a case study in Germany

Hydrogen refueling stations are an important part of the infrastructural development that should be developed in order to realize a 100% sustainable economy for the future. Most of the refueling stations are located within urban areas but there are many located outside urban areas or in remote areas. Hydrogen could either be transported to these sites or being locally produced with integrated sustainable energy systems. In this study the potential number for wind powered hydrogen refueling stations using GIS is determined. Furthermore the amount of hydrogen that could be produced and used is determined via energy system simulation. Finally the hydrogen production and dispensing costs are calculated.</p

Performance Characteristics of a Micro Wind Turbine Integrated on a Noise Barrier

Micro wind turbines can be structurally integrated on top of the solid base of noise barriers near highways. A number of performance factors were assessed with holistic experiments in wind tunnel and in the field. The wind turbines underperformed when exposed in yawed flow conditions. The theoretical cosθ theories for yaw misalignment did not always predict power correctly. Inverter losses turned out to be crucial especially in standby mode. Combination of standby losses with yawed flow losses and low wind speed regime may even result in a net power consuming turbine. The micro wind turbine control system for maintaining optimal power production underperformed in the field when comparing tip speed ratios and performance coefficients with the values recorded in the wind tunnel. The turbine was idling between 20%–30% of time as it was assessed for sites with annual average wind speeds of three to five meters per second without any power production. Finally, the field test analysis showed that inadequate yaw response could potentially lead to 18% of the losses, the inverter related losses to 8%, and control related losses to 33%. The totalized loss led to a 48% efficiency drop when compared with the ideal power production measured before the inverter. Micro wind turbine’s performance has room for optimization for application in turbulent wind conditions on top of noise barriersEnergy TechnologyWind Energ

Wind resource characteristics and energy yield for micro wind turbines integrated on noise barriers: An experimental study

This paper assesses wind resource characteristics and energy yield for micro wind turbines integrated on noise barriers. An experimental set-up with sonic anemometers placed on top of the barrier in reference positions is realized. The effect on wind speed magnitude, inflow angle and turbulence intensity is analysed. The annual energy yield of a micro wind turbine is estimated and compared using data from a micro-wind turbine wind tunnel experiment and field data. Electrical energy costs are discussed as well as structural integration cost reduction and the potential energy yield could decrease costs. It was found that instantaneous wind direction towards the barrier and the height of observation play an influential role for the results. Wind speed increases in perpendicular flows while decreases in parallel flow, by +35% down to −20% from the reference. The azimuth of the noise barrier expressed in wind field rotation angles was found to be influential resulted in 50%–130% changes with respect to annual energy yield. A micro wind turbine (0.375 ​kW) would produce between 100 and 600 ​kWh annually. Finally, cost analysis with cost reductions due to integration and the energy yield changes due to the barrier, show a LCOE reduction at 60%–90% of the reference value.Energy TechnologyWind Energ