16-01-2013, 04:00 PM
Wind Power
Wind Power.pptx (Size: 2.69 MB / Downloads: 48)
Introduction
Wind energy is mainly used to generate electricity. Wind is called a renewable energy source because the wind will blow as long as the sun shines.
Wind energy is plentiful, renewable, widely distributed, clean, and reduces greenhouse gas emissions when it displaces fossil-fuel-derived electricity.
The History of Wind
American colonists used windmills to grind wheat and corn, to pump water, and to cut wood at sawmill.
In the 1920s, Americans used small windmills to generate electricity in rural areas without electric service.
The oil shortages of the 1970s changed the energy picture for the country and the world.
It created an interest in alternative energy sources, covering the way for the re-entry of the windmill to generate electricity.
In the early 1980s wind energy really took off in California, partly because of state policies that encouraged renewable energy sources.
How Wind Machine Work
Wind machines use blades to collect the wind’s kinetic energy. The wind flows over the airfoil shaped blades causing lift, like the effect on airplane wings, causing them to turn. The blades are connected to a drive shaft that turns an electric generator to produce electricity.
Vertical-axis Wind Machines
Vertical–axis wind machines have blades that go from top to bottom and the most common type (Darrieus wind turbine) looks like a giant two-bladed egg beaters.
The type of vertical wind machine typically stands 100 feet tall and 50 feet wide. Vertical-axis wind machines make up only a very small percent of the wind machines used.