Saturday, November 5, 2011

Wind energy | Vertical axis turbines 10 times more efficient than the traditional

The study has been developed by the California Institute of Technology (Caltech) and it has carried out a study of single field so far, in a wind park pilot of two hectares located in the North of Los Angeles. In this park are installed 24 turbines of vertical axis (vertical-axis wind turbines or VAWTs) 10 meters high and 1.2 meters wide.

Despite improvements in the design of the wind turbines that have increased their efficiency, wind farms are still quite inefficient. According to Dabiri - director of research - this can be resolved with a proper installation of the turbines.
The modern wind farms usually employ horizontal axis turbines (horizontal-axis wind turbines or HAWTs), the most famous, with their typical format of a high tower with a propeller that rotate slowly.
These holdings, the turbines individual must be widely separated between themselves. Not just enough so that their giant blades do not touch, but much more, since the wake of wind generated may interfere the aerodynamics of the neighboring turbines. This great distance implies a greater amount of land and therefore more investment.

There have been - it says - a tendency to try to compensate for this loss of energy making larger propellers and the more high towers, to absorb the energy of the wind at higher altitudes, there where bursts are more powerful. But this brings other problems, such as higher costs, more complex engineering problems and a greater environmental impact.

Models for HAWTs and VAWTs
The solution, says Dabiri, is to focus on the design of the wind farm itself, to maximise efficiency in the Heights close to the ground. To this end the turbines VAWTs (vertical axis) are ideal, since that can be placed very close to each other. This allows them to capture nearly all of the energy of the wind.

You have each turbine rotating in the opposite direction to its neighbors, also enhances its effectiveness. As explained, this decreases the friction allowing the turbine to spin faster.

In field tests conducted during the summer of 2010, Dabiri and his colleagues measured the speed and the power generated by each of the six turbines, placing them in a number of different configurations. This was done by leaving a turbine in a fixed position while the other had a system of portable site that allowed that they were displaced.

Tests showed that when the you turbines were placed spaced between Yes by a distance of approximately 5 meters (equivalent to 4 diameters of the turbine) was removed entirely interference aerodynamics between neighboring turbines. In comparison, the Elimination of aerodynamic interference between the largest currently in use horizontal axis turbines require a space of about 20 diameters of distance (more than one mile).
The six vertical axis turbines (VAWTs) generated between 21 to 47 Watts of power per square meter of land. While a comparable size farm consisting of horizontal axis (HAWT) turbines were generated as little as 2 to 3 Watts per square meter.

View the original article here