Wind: the earth is unevenly heated by the sun as the sun's radiation heats different parts of the earth at different rates – most notably during the day and night, but also when different surfaces (for example, water and land) absorb or reflect at different rates. The differential heating drives areas of the atmosphere to have different temperatures; some places are warmer while some are cooler. Hot air inflates and rises to the stratosphere, reducing the pressure of the earth’s surface; as a replacement, the cooler air moves closer to the surface. As the exchange process continuously occurring, this results in wind.

Wind Energy: wind power can be converted into other forms of energy, i.e. electricity. This process is realized by wind turbines. Wind energy as an alternative power resource is favored by environmentalists because it is renewable, abundant, widely distributed and environmentally friendly, which produces no greenhouse gas. On the contrary, the establishment of wind farms is not generally approved due to their environment impact.

Wind energy is a converted form of solar energy.

As air has mass (m) and is in motion, which implies certain level of velocity (v), it generates kinetic energy.

Some portion of this energy is transformed into other sorts of energies, i.e. electricity. In addition, the motion of wind encounters friction. Because of this friction, the wind energy is converted into diffuse heat throughout the Earth's surface and the atmosphere. The total amount of economically extractable power available from the wind is considerably more than present human power use from all sources.

Wind Turbines: wind energy systems transform kinetic energy into mechanical or electrical energy for various purposes. Mechanical energy is mostly used to pump water in rural areas. Wind electrical turbines also produce electricity for homes and businesses.

There are two basic designs of wind turbines: vertical-axis and horizontal-axis. Nowadays, the latter type is more commonly adapted globally. The components of a turbine are:

• a rotor (or blades) that converts the wind's energy into rotational shaft energy
• a nacelle (enclosure) containing a drive train, usually including a gearbox and a generator
• a tower, to support the rotor and drive train
• electronic equipment such as controls, electrical cables, ground support equipment, and interconnection equipment.

Wind turbines vary in size. From 1981 to 2008, rotors’ diameters ranged from ten to 126 meters (33 to 413 feet). The world’s largest turbine was constructed by the UK in the year of 2008. A single turbine of this size can support up to 500 homes. Wind turbines for residential homes or small businesses are usually small, with rotor diameters of eight meters or less, and mounted on towers of 40 meters in height or less.

Electricity generated by wind turbines: the capacity of turbines to generate electricity depends on the size of the rotors and the wind speed. The volume is usually present in kilowatt-hour (kWh, 1,000 watts). A kilowatt-hour means one kilowatt (1,000 watts) of electricity produced or consumed for one hour. The wind turbines presently being manufactured have power ratings ranging from 250 watts to five megawatts (MW, 5 million watts). One megawatt of wind energy can generate from 2.4 to more than 3 million kWh annually. An average U.S. household uses about 10,655 kWh of electricity per year. Therefore, a megawatt of wind generates about as much electricity as 225 - 300 households consume.

Capacity factor: Capacity factor is one element in measuring the productivity of a wind turbine or any other power production facility. It compares the plant's actual production over a given period of time with the amount of power the plant would have produced if it had run at full capacity for the same amount of time.

Cost of Wind Energy: wind is emerging as a low-cost renewable energy source. The cost of wind energy dropped from 30 cents per kilowatts-hour in the 1980s to 5 cents/kWh. In addition, a Renewable Energy Production Tax Credit of 2.1 cents per kWh is available in the U.S.

The major factors that affect the cost of wind energy are the size of the wind farm, wind speed and cost of installing turbines.

1. All other variables equal, the larger the size of the wind farm, the lower the cost of wind energy. With the same wind speed and similar construction cost of the turbines, larger wind farms allow the cost to spread over more kilowatt-hours which leads to the lower cost per unit. This can also be explained by the theory of economics of scale, which implies reduction in long-run average and marginal costs, due to increase in size of an operating unit, i.e. wind farm.
2. The higher the wind speed, the lower of the wind energy cost. In the paper “The Economics of Wind Energy” by the American Wind Energy Association, it states that the energy produced is directly proportional to the wind speed. In fact, even a very slight increase in wind speed can cause a large increase in the energy generated.
3. The less expensive the installment, the lower the energy cost. This concept is rather straightforward. It can be executed by improving the design of the turbines. The taller the turbine tower, the longer rotor diameter it can support, and the larger the area swept by the blades. Thus, the more productive the turbine. Furthermore, wind speed grows faster with distance from the ground so higher towers also reduce energy costs by providing the advantage of greater wind speeds.