A wind turbine is a device that converts kinetic energy of wind into mechanical energy. When mechanical energy is put to use directly in some equipment such as grinding stones or a pump, it is called a windmill. Instead, when it is converted to electricity for further use, the device is known as wind turbine or wind generator. Wind turbines are mounted at high elevation so as to receive a constant flow of wind power at higher average velocity. Usually, wind turbines need an average speed of 35 kilometer/hour or 11 meters/second. Wind velocity mapping is done before selecting a place for wind turbine. Higher the wind speeds, more are the chances to get continuous flow of electricity (Whitburn, 2012).
As terminology implies, 1- kW rated capacity wind turbine would generate theoretically maximum of 1 kW of power per hour, if continuous flow of wind with the average wind velocity is available at all the time; however, in all practical purposes it does not happen so because wind energy is intermittent. In the long run, wind turbines are found to generate electricity only at 10-40% of their rated capacity. This means that wind turbine with the rated capacity of 1 kW would generate between 2.4 kWh (1× 24× 0.10) and 9.6 kWh of power per day (1×24× 0.40) (Whitburn, 2012).
Wind turbines can be segregated on the basis of horizontal- and vertical-axis turbines. Horizontal-axis turbines have tail fins that keep blades facing the wind. A constant flow of wind keeps turning the rotor blades of the turbine, which is connected to the generator through a rotating shaft and gear-wheel assembly. The power so generated is called Direct Current (DC) and needs to be converted to Alternating Current (AC) for its use as all devices for home use are usually designed based on AC current. The conversion from DC to AC is done through a device called inverter. Inverter is connected to a battery bank that is a store house of electricity produced in this way because wind energy is available intermittently while electricity demand is continuous. When no sufficient wind energy is available, electricity production comes to a standstill; however, the need of end users are met through the stored energy in the pool of battery (Whitburn, 2012). The following schematic shows the steps involved in the production of wind power. Source: http://exploringgreentechnology.com/wind-energy/how-does-wind-energy-work/ How Wind Energy Can Save Money Companies can save a huge amount of money if they use this renewable source of energy. Subsidies that are available at Federal and State levels give extra cushioning; technological advances and scale of operations have changed the scenario in clear terms. Subsidies Available on Wind Energy The production tax credit (PTC) is the subsidy available to the producers of wind power and that, currently, rules at 2cents/kWh (zFacts, 2011). Most of the wind generators have qualified for this and they will receive it for 10 years. Moreover, double declining 5-year depreciation is the second benefit that companies get on investment toward wind power. This allows investor to take a 40% tax deduction on the very first year and 24% deduction on the second year. It is allowed to be completed in five years. The combined federal-sales tax rate is around 43% and in that sense the depreciation allowance is lucrative enough and in terms of benefits, it accounts for half a cent/kWh (zFacts, 2011). Though wind produces electricity free of operating cost, it requires still huge investment toward the cost of equipment and installation