WHAT WE CAN DO​

After solar power, wind power is the next major source of renewable energy that has a high global potential with the least environmental impact. Wind energy is converted to electrical energy using wind turbines of various sizes, capacities, and types.

The most common types of wind turbines are the horizontal axis wind turbines (HAWT). Horizontal refers to the axis of the turbine rotor, and not the tower or any supporting structure. Horizontal-axis wind turbines are found in various sizes and capacities ranging from a few watts or kilowatts in residential installations, to 100m tall megawatt-class turbines used in commercial power generation. Commercial wind turbines are also now found as enormous multi-megawatt class turbines of more that 7-megawatt each, measuring well over 100m tall.

Two forms of VAWTs (left and right), as compared to a common HAWT (centre). Due to the relatively recent technology, VAWTs does not have a fixed form as with HAWTs, and is available in various more designs. Source: Wikimedia Commons/Public Domain.

The cost of wind power (particularly HAWTs) has drastically dropped within the past decade due to major breakthroughs and economies-to-scale due to the high purchase and installation of these large machines. The largest single operating wind farm in the world as at December 2011 is the Roscoe Wind Farm in the United States, with an installed capacity of 781 megawatts.

The Estinnes Wind Farm under construction in Belgium, 2010. The wind farm consists of 11 turbines of 7.5-megawatt each, all of which measuring nearly 200 meters tall. Source: Wikimedia Commons/Public Domain.

Although not applied on a commercial scale, smaller vertical-axis wind turbines or VAWTs are becoming more common where winds are constantly changing directions or are turbulent. Due to the structure of VAWTs (as shown below), these units does not need to be constantly pointed towards the direction of the wind, as is required by HAWTs. The primary reason why these are not developed at a commercial scale is due inefficiencies and aerodynamic drag created.