Vertical wind turbines might be in future
An article reproduced in Scientific American's August 18, 2011 online edition says that vertical wind turbines have some advantages over the traditional propellor-type horizontal turbines.
An article reproduced in Scientific American’s August 18, 2011 online edition says that vertical wind turbines have some advantages over the traditional propellor-type horizontal turbines.
Written by Umair Irfan and ClimateWire, the article quotes Paul Veers, chief engineer at the U.S. National Renewable Energy Laboratory. He explains that vertical axis turbines, where the rotating axis is upright, have existed as long as the horizontal turbines. However, vertical turbine technology has not received as much attention, research and funding by manufacturers for use on a commercial scale.
Currently vertical turbines are mostly used for houses, mounted on poles or rooftops. They might look something like an egg whisk, with narrow blades anchored at both ends to the vertical shaft. Another design involves air scoops which form a spinning cylinder.
One advantage of the vertical propellers is that the generators can be placed lower to the ground, which means their maintenance costs are lower. The low level generators also make them a good candidate for very large offshore wind farms, where their lower centre of gravity gives them more stability on floating platforms and enables them to better withstand the high winds out on the ocean.
Vertical turbines that are counter rotating can be arranged to have a higher output of power per unit area of land than conventional propellor turbines, according to professor John Dabiri at the California Institute of Technology, who was also quoted in the article.
The disadvantages are that vertical turbines have dynamic loading and a dynamic structure, which leaves the rotors vulnerable to tearing themselves apart. They also have an inherently higher mass-to-power ratio than their horizontal, propeller cousins.
To see the article, click here.