Sources of electricity : wind power

The wind is able to move things, like the branches of trees, fabric of boats, even more at high speeds. It comes from a difference of pressure in the air.

Let me introduce you to wind power. First, we will see how it works. Second, we will see the advantages and drawbacks of wind electricity.

I How a wind turbine works
II Advantages and drawbacks of wind electricity

I How a wind turbine works

The wind activates the wind turbine blades by a mechanism of forces.

The wind force F1 exerces a repell force F2, that produces another force F3 with F1 = F2 + F3. F3 makes the blade turn around the wheel.

The wheel turns and activates a gear box, that activate a generator, that makes electricity.

Sketch of the inside of a wind turbine.

Let's focus on the following formula :

p = 1/2 x ρ x S x v³ x C_p

In this formula,

• p is the power, in Watts, produced by the wind turbine ;
• ρ is the volumic mass of air ;
• S is the area of the wind turbine ;
• v is the speed of the wind turbine ;
• C_p is the coefficient of performance, a corrective parameter between 0 and 1.

We notice that the power produced by the wind turbine is proportional to v³. It means that the production of a wind turbine is highly sensitive to the speed of wind. If the wind goes 2 times faster, the production is 2 x 2 x 2, that is 8 times higher. If the wind goes 3 times faster, the production is 3 x 3 x 3, that is 27 times higher.

Classical Danish wind turbines.

Actually, the classical Danish wind turbines stop at high speeds. But it's possible, with flexible blades, to make wind turbines that work at high speeds.

In 1955, the CIAMO (Compagnie Industrielle des AéroMOteurs) made the FP5 and FP7 wind turbines, that work in cyclonic conditions. They were working from 3 m/s to 90 m/s. In my opinion, they made the most powerful wind turbines in the history of wind energy.

II Advantages and drawbacks of wind electricity

+ Renewable ;
+ Clean ;
- Produces enough only on mountain tops or sea coast ;
- Only works when there is wind.

I don't talk about the birds, 99 % of the time they avoid the blades, and only stupid birds die, it's not a problem to get rid of them.
I don't talk about the noise, it's likely the same as cars, which are largely accepted. I think it's possible to get used to it.

As a renewable source of energy, wind electricity is a solid alternative to depletable energies like fossil fuels or nuclear, which meet difficulties and high cost of damage in the long term. Fossil fuels burn the planet, which suffers from more droughts and a loss of food production, and the Fukushima catastrophe cost 210,000,000,000 $ of damage and ruined a country. On the contrary, renewable energies like wind electricity are long-term efficient, and are compatible with sustainable development :-) .