Since earliesttimes, man has harnessed the power of the wind, with the first mill recorded aslong ago as the 6th century AD. The technology has diversified over the yearsto include pumping water, grinding grain, powering sawmills and most recentlygenerating electricity, now the fastest growing energy sector worldwide.1Todaythere are various types of wind turbines in operation, (fig. 1 gives anoverview). The most common device is the horizontal axis wind turbine. Thisturbine consists of only a few aerodynamically optimized rotor blades, whichfor the purpose of regulation usually can be tumbled about their long axis(Pitch-regulation).
Another cheaper way to regulate it, consists in designingthe blades in such a way that the air streaming along the blades will go intoturbulence at a certain speed (Stall-Regulation). These turbines can deliverpower ranging from 10 kW to some MW.An LED lighting initiative is a commonattempt to reduce the energy consumption. By installing energy-efficient LEDlighting technology, we can lower energy consumption, decrease maintenancecosts, and lessen wear and tear on heating and cooling systems.
As one of theleast risky sustainability practices with a rapid return on investment of less thanthree years in many cases. LEDs have longer lifespans and lower energyconsumption levels than conventional bulbs. A major advantage of an LED is lowenergy consumption and operation lifetime with no or minor maintenance whencompared to traditional lighting, such as HIDs, incandescent, fluorescent, etc.The cost of LED lighting may be an issue when a major retrofit is planned oncampuses, but the payback will be around three or four years, depending oncapacity of the LED lighting deployed. LED lights are similar to typical lightbulbs, with the main difference being that they do not have a filament inthem—the reason why they burn for so long. Because LEDs do not use a filament,they also do not get hot, and they run on less electrical power, making themmore energy-efficientof interconnection.
Small wind turbinesproduce a variety of voltages and some produce DC power. Small wind turbinesgenerally require an inverter to match the power output with the load and/orinterconnection frequency and voltage.Wind turbines produce electricity byusing the natural power of the wind to drive a generator. The wind is a cleanand sustainable fuel source, it does not create emissions and it will never runout as it is constantly replenished by energy from the sun. Blades captureenergy in the wind and turn the turbines. Control mechanisms point the bladesinto the wind (yaw control) and, on large wind turbines, adjust the pitch ofthe blades (blade angle) as wind speeds change. Typically, a gearbox connectsthe shaft from the blades (rotor) to the electrical generator.
The electricalgenerators used on wind turbines may either be induction generators orsynchronous generators. The electrical power from the generator is typical 60Hz, AC power with 600V output for large wind turbines. A transformer may berequired to increase or decrease the voltage so it is compatible with theendues, distribution or transmission voltage, depending on the type