Global Wind Energy Council (GWEC) figures show that in 2008, due to stunning growth in the US and Chinese markets, the industry exceeded all expectations to end up with an annual market of more than 27 GW. This brought the global market up to more than 120 GW. These figures show that there is huge and growing global demand for emissions-free wind power, which can be installed quickly, virtually everywhere in the world. The sector now employs more than 400,000 workers around the world and the value of new power generation equipment installed in 2008 exceeded € 36 billion (nearly $US 50 billion).

The US installed a record 8.4 GW, catapulting it past Germany to the number one spot in terms of global installed capacity, and creating 35,000 new jobs in the process, bringing the total employed in the sector up to 85,000. The massive growth in the US wind market in 2008 increased the country’s total wind power generating capacity by half. The new wind projects completed in 2008 accounted for about 42% of the entire new power producing capacity added in the US last year.

At year’s end, however, financing for new projects and new orders for turbines and components slowed as the financial crisis began to hit the wind sector, taking a serious toll on financing available for new projects. This in turn is dampening orders for new turbines, with repercussions throughout the supply chain.

Looking ahead, in spite of the concerns about the financial crisis and its spillover into the real economy, the wind industry continues to be in a strong strategic position. All of the fundamental drivers behind its growth remain in place. In 2008, the US Department of Energy released a groundbreaking report, finding that wind power could provide 20% of US electricity by 2030. With the wind energy industry’s strong performance in 2008 and the support of the new Obama Administration, the industry is in a position to turn this scenario into reality, or even surpass it.

An estimated 1% to 3% of energy from the Sun that hits the earth is converted into wind energy. This is about 50 to 100 times more energy than is converted into biomass by all the plants on Earth through photosynthesis. Most of this wind energy can be found at high altitudes where continuous wind speeds of over 160 km/h (100 mph) occur. Eventually, the wind energy is converted through friction into diffuse heat throughout the Earth's surface and the atmosphere. Wind power is the conversion of wind energy into more useful forms, usually electricity, using wind turbines. Globally, wind power generation more than quadrupled between 2000 and 2006.

The power in the wind can be extracted by allowing it to blow past moving wings that exert torque on a rotor. The amount of power transferred is directly proportional to the density of the air, the area swept out by the rotor, and the cube of the wind speed.

The power P available in the wind is given by:

where:
P = power [watts]
ρ = air density [kg/m^3]
A = area swept out by rotors [m^2]
u = wind velocity [m/s^2]

The mass flow of air that travels through the swept area of a wind turbine varies with the wind speed and air density. As an example, on a cool 15°C (59°F) day at sea level, air density is 1.225 kilograms per cubic metre. An 8 m/s breeze blowing through a 100 meter diameter rotor would move almost 77,000 kilograms of air per second through the swept area. Amounting to about 2.5MW of power.