Slow, Medium Speed Wind Turbines

ogether, they constitute around 73.0% of the global wind generation. Though these countries have high wind speed locations that have been developed till now, the average wind speeds (shown in Table 1) fall in the medium to low wind speed classes of IEC (table 2). This indicates the enormous wind energy potential in the low and medium wind speed conditions that have not been harnessed effectively.

Table 1: Average Wind speeds in Major wind power generating Countries

Wind turbines are classified by IEC into four categories, as per the wind conditions in which they are installed.

Table 2: IEC Wind turbine Classes

Till recently, wind manufacturers were busy selling turbines only to the high wind speed region, but it is believed that with saturation of space in this market, these companies need to look for new technology and untapped market of low and medium wind speed power generation market.

Technically, power generated by the wind turbine is proportional to wind velocity cubed and rotor blade swept area. As, the wind velocity reduces, the rotor diameter has to be increased to obtain equivalent power output.

Source: Frost & Sullivan Analysis

Development Opportunities in Low and Medium Wind Speed conditions

Keeping aside the offshore potential, more than half of the total onshore wind energy potential lies in the low and medium wind speed regions. However, currently, only 15% of the total wind power generation is based on medium and low wind speeds globally. It is estimated that high wind speed regions such as Europe, North Africa and countries such as China, US, Australia, India and Argentina also have enormous locations with medium and low wind speeds that are yet to be developed. While most of the high wind speed regions are remote and away from population centers, the low and medium wind speed locations are nearer to the urban population which alleviates the problem of transmission grid congestion. Most turbine manufacturers' focus on equipment for high wind speed conditions, however, some of them have been foresighted to develop larger turbines to suit low and medium wind speeds.

Major Wind Turbine OEMs' Product Portfolio Includes Turbines for Medium-Low Wind Speed Conditions

Recent developments by some of the major wind turbine OEMs to harness power from medium-low wind speed conditions include the following:

• Denmark based Vestas pioneers in low wind speed turbines. They have developed large rotor turbines of 100 and 110 m rotor diameters on 2.0 MW platforms, and 126 m diameter on 3.0 MW platforms to suit medium and low wind classes. Vestas' 3 MW slow speed turbines  is highly successful and won orders worth 3.0GW  in 2013, as it has the highest wind generation potential from low speed conditions.
• US based General Electric has developed new turbines of 1.5 MW for low wind speeds.The company uses doubly-fed induction generator (DFIG) for wind power generation; the models are known to be morAir Jordan XII 12 Shoes