12. Wind

Wind power is a fast-growing energy source. The power of the largest wind turbines is well in excess of one MW. A 2 MW wind turbine is 80 to 125 m high and weighs 300 t. The power indicated is obtained when the wind is strong enough (at least 55 km/h, or force 7 on the Beaufort scale). The power varies as the cube of the wind speed (it is multiplied by 8 if the wind speed is multiplied by 2), so that at low speeds virtually no electricity is produced. If the wind is too strong, above 90 km/h, it must be stopped, otherwise the turbine could be irreparably damaged.

The largest wind turbine in existence today is an offshore wind turbine built by the Danish company Vestas. The V164 is 140 m high, has an output of 8 MW and a rotor diameter of 160 m. To give an idea of the scale of the gigantism now being achieved, let's say that in the circular area swept by the 35 m-long...