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Turbines in the city

Unlike large wind farms located in areas with strong winds (elevations, marine parks, ...) and machines equipped with large powers of the order of several megawatts but far from consumption centers, the location of small wind turbines cities can generate power where it is needed, minimizing losses and simplifying their transportation infrastructure.

To this end there have been various proposals to achieve the architectural integration of wind power and small size, located in most cases in varying numbers on the roofs of buildings. Other less conventional configurations have been carried out, such as the Bahrain World Trade Center, with three turbines installed on two separate bridges connecting two buildings, or are in the project, such as David Fisher rotating skyscraper that involve insertion between each two floors of a vertical
axis wind turbine design very special. In any case, it raises several problems that, while affecting all wind turbines are most important when considering their use in urban environments.

The first is security. Wind turbines are rotating machines with moving parts outside of large size. Although they are inaccessible location under normal conditions, is always latent risk of a rupture of the blades, which fragments could fall to the street. The rotors are also a hazard to birds, which may face impacts while the blades are damaged.
Second, is the problem of noise generated in their operation and that would add to the already numerous existing sources in cities. In the end, but not least is the aesthetic factor.  With these challenges in mind, the Energy Technology Institute of Valencia has been promoting a line of research for the development of wind turbines for urban integration has led to the development of a prototype mini-vertical axis wind turbine (600 W) will be used for the study of technical solutions to these problems. The choice of vertical axis configuration is that this type of turbine is able to harness the wind regardless of direction, requiring therefore a guidance system as the horizontal axis.

This is especially interesting in the cities, where the turbulence levels are high and the wind direction changes frequently. Other advantages are the low level of noise generated and appearance, considered more aesthetically suited to urban settings in a majority. The prototype developed is called the rotor-H type, with approximate dimensions of 1.90 m in diameter and 2.15 of total height, and taking advantage of their energy mainly generated lift forces that occur on their blades to rotate in the within an air stream. It differs therefore Savonius type wind turbines, which use wind drag forces, thus limiting its speed and makes them less suitable for generating electricity. 

The purpose of this wind turbine is to serve as a testbed to study the different settings, because thanks to its interchangeable blade system allows you to mount a variable number of these (between 2 and 5), and try different profiles and angles of incidence , in order to achieve maximum energy efficiency with low noise. In its construction have been used advanced composite materials that provide lightweight while strength and fatigue resistance to withstand the demanding mechanical stresses to which they will be subject, as at every turn the blades are exposed to the action of wind from all angles, causing alternative efforts on them. The design and optimization of the geometry of the turbine has been performed using CFD modeling techniques (Computational Fluid Dynamics) and its structure using finite element analysis.


BY: Juan Pablo Gonzalez, head of energy infrastructure. Institute for Energy Technology (ITE, Spain)

2012/09/27 by Gloria Llopis