About wind

To understand wind energy as a whole, technical competence and experience is required. It makes sense to us to explain to you some of the parameters relating to the power of the wind. The same principle applies to everything: not all wind is the same.

The power in wind

Wind is a balancing stream between high and low air pressure areas. Wind turbines use the kinetic energy of the wind and transform it into rotation. In this way mechanical energy is created, and with a generator it is transformed into electrical energy. What type of wind is the right one for generating wind energy? At our latitude, we have the main wind directions from the west and northeast. Mainly coastal regions and areas with regular, constant flows are used for wind power. However, not only countries with constant, strong winds, but also regions with changing wind directions and irregular winds offer adequate potential.

Not all wind is the same

Wind is not a static entity . Wind behaves differently in different situations. A calm wind at ground level does not mean that the same conditions prevail at fifty metres or higher. Height and temperature influence the air density measurably. The air density is decisive for energy production of a wind turbine. The air density is thinner at increasing heights. This fact must be taken into consideration, especially with the installation of a system in the mountains.

Distribution pays

Not only the speed, direction and density of the wind define the performance of a wind energy system, but also the wind distribution plays a major role. Here it is necessary to find out how the various wind speeds are distributed during a specific time period. It also applies here that: 5 m/s is not the same as 5 m/s.

Third power for eight-sided performance

Assuming that the wind blows with a speed of 10 m/s for 30 minutes. The next 30 minutes are calm. The average wind speed in this hour is 5 m/s and the ensuing theoretical output is around 300 Wh/m² (watt hours per m²). As a comparison, we calculate one hour with a constant 5 m/s and get a theoretical output of around 75 Wh/m². Why is the wind performance four times smaller with the same average wind? The third power of the speed has the answer. If the wind speed doubles, we get eight times the output. The higher the percentage of strong wind, the more energy is yielded.

Wind assessments creates clarity

Changing wind conditions - a storm or gusts - therefore result in strong variations in output. How can we evaluate the yield of a wind turbine with these variable winds? With the help of wind assessments at the location of the planned wind energy system. The wind assessments provide detailed information about the wind quality at the location and provides clarity about whether the investment in a wind turbine is worthwhile.

    Good to know

    Kilowatt hour (kWh)

    The kilowatt hour, often also called watt hour, is shortened to kWh or Wh. This unit of measurement describes the work, or rather the energy. With 1 kWh of energy, you can vacuum, for example, for 25 minutes or heat a bucket full of water (10.75 litre) under normal pressure from 20 to 100 degrees Celsius.

    Volt amps (VA)

    The volt amp (VA) is the product of electrical voltage and the electrical current and is the unit for the electrical apparent power. These are a combination of the active power and the idle power. The apparent power is decisive for the design of the electronic components.

    Watt (W)

    The watt (W) is the SI unit for the power (work per time). In electrical engineering, the watt is used exclusively for the calculation of active power.

    1 W = 1 J/s = 1 (Nm)/s

    Metre per second (m/s)

    Metre per second (m/s) is the derived unit of speed in the SI unit system. An object that moves with a speed of 1 m/s covers a distance of one metre in one second. Many speeds are typically given in km/h instead. The conversion of m/s to km/h uses a factor of 3.6.

    Beaufort (Bft)

    The Beaufort scale Bft is a scale for the classification of wind according to its speed. It is the most used system in the world. The Beaufort scale is named after Sir Francis Beaufort, although he only played a small part in its development.

    Envergate Energy AG

    Seestrasse 21

    CH-9326 Horn TG

    SWITZERLAND

     

    Tel +41 71 844 54 44

    info(at)envergate.com

    www.envergate.com

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