Wind energy is the energy from air flow moving from areas of high pressure to areas of low pressure. It's a byproduct of solar radiation. As the sun heats the earth unevenly with solar radiation being greater at the equator than at the poles, the resulting differential temperatures creates a differential in air mass densities and atmospheric pressure leading to a bulk movement of air, wind. The wind energy can be extracted from air flow to produce mechanical or electrical power.

Windmills or wind-powered mills have been used for centuries to produce mechanical and used in various applications such as water pumping, irrigation or cereals grinding. Nowadays, wind power is harness to generate electricity using wind turbines. Wind turbines operate on a simple principle. They convert the kinetic energy from the wind into electrical power. The energy in the wind turns two or three blades around a rotor, which is connected to the main shaft, which in turns  spins a generator to produce electricity. 

Wind flow my be consistent from year to year, but it is known to be very intermittent with significant variation over short periods of time. Because of that, wind power is often used in conjunction with other more stable form of energy, such as fossil fuels. Since the the late nineties, wind power technologies have grown remarkably with large wind farms inland and offshore being installed in many countries, like the United States and Northern Europe. According to the Global Wind Energy Council (GWEC), 51,473 MW of new wind generating capacity was added in the single year of 2014 and the total cumulative installations were above 369 GW by the end of that same year.

Wind power is justifiably praised to be a clean, renewable source of energy because it does not produce greenhouse gases and many other pollutants that degrade the environment. Moreover, with continuous technological advancement, it has become economically viable and offer an excellent opportunity to attain the goal of sustainable development. However, despite those claims that are in fact true, it's also true that some wind power projects have been in some cases associated to a lesser extent to some environmental issues. The main environmental concerns relate to the loss of agricultural land, noise disturbance, landscape aesthetic visual impact, the decrease of property values as well as  bird vulnerability.