Information about wind power
Here are some useful information about wind power and how it can help in providing decentralised electrical power supply
Wind energy = kinetic energy and its W/s equivalent
| Bft | Speed in m/sec | Power content in W/s; ca. |
| 0 | 0 - 0,2 | 0 - 0,005 |
| 1 | 0,3 - 1,5 | 0,02 - 2,0 |
| 2 | 1,6 - 3,3 | 2,5 - 24,9 |
| 3 | 3,4 - 5,4 | 25 - 95 |
| 4 | 5,5 - 7,9 | 100 - 300 |
| 5 | 8,0 - 10,7 | 310 - 740 |
| 6 | 10,8 - 13,8 | 760 - 1.580 |
| 7 | 13,9 - 17,1 | 1.610 - 3.000 |
| 8 | 17,2 - 20,7 | 3.050 - 5.350 |
| 9 | 20,8 - 24,4 | 5.400 - 8.750 |
| 10 | 24,5 - 28,4 | 8.850 - 13.800 |
| 11 | 28,5 - 32,6 | 13.900 - 21.000 |
| 12 | > 32,7 | > 21.000 |
Definition: How is "Small wind" defined?
According to the world wind energy association the word "small" in the wind industry has been and remains vague and ever changing. The lack of a credible unanimous definition and casual practice of the industry has created a term that describes wind turbines with a rated capacity from 6 watt to as large as 300 kW.
Small wind was originally defined by its characteristics to produce small amount of electricity for house appliances or to cover various household-based electricity demand.
One single 40 inch LED television on the market today consumes approximately 200 W. Assuming that a battery can completely flatten off the fluctuation in supply and demand, it is estimated that an 180 W turbine can sufficiently sustain the television to be turned on for 4 hours per day1.
An average American family uses 11’496 kWh of electricity yearly. Under the same assumptions, a 10 kW turbine is needed to cover the full consumption. In comparison, a European household demands a 4 kW turbine while an average Chinese household requires as small as a 1 kW turbine.
Assuming that small wind is to supply the small consumption of households, the issue of whether a 100 kW turbine may be categorised as small wind needs to be brought onto the debate table.
IEC 61400-2 defines SWTs as having a rotor swept area of less than 200 m2, equating to a rated power of approximately 50 kW generating at a voltage below 1’000 V AC or 1’500 V DC.
Currently, in the world today individual countries are setting up their own definition of small wind while conducting market researches, drafting renewable energy laws or offering providing financial aid programs.
The discrepancy of the upper capacity limit of small wind ranges between 15 kW to 100 kW for the five largest small wind countries. In the case of the United Kingdom, for example, due to the interest of various parties, the definition of small wind even differs between the national wind energy association, Renewable UK, and its MCS certification body.
