​Wind Energy


Wind Energy


shown in the picture above the earlist known design is the vertical axis system developed in Persia about 500-900 A.D. The use of the mill was to grind grains and pump water from lower area.

Wind energy comes from running wind mills. Another use of wind mills was wind power for the sail boats. That technology had an important impact on the later development of sail-type wind mills. The sailors understood that this invention worked but they never understood why is did. Later on the persians used the power of wind to grind up there wheat thounsands of years ago. Also another group that has been using wind mills is the Dutch, they used it to pump water from lower areas. They also used the wind mill to drain lakes.


The horizontal-axis was the first kind of wind mill that came to western Europe. The purpose of the rotor, of course, is to convert the linear motion of the wind into rotational energy that can be used to drive a generator. The same thing is used in a modern water turbine, where the flow of water is parallel to the rotational axis of the turbine blades.


The vertical axis wind turbines are like water wheels. Some vertical axis turbine could work with a horizontal axis. But they would hardly be able to beat as fast as a vertical axis turbine. The only vertical axis turbine which has ever been manufactured is the Darrieus machine, named after the French engineer Georges Darrieus who made the design in 1931. It was manufactured by the U.S. company FloWind which went bankrupt in 1997. The Darrieus machine is characterised by its C-shaped rotor blades which make it look a bit like an eggbeater. It is normally built with two or three blades.

Early 1390's the Dutch set out to refine the tower mill design. The Dutch fixed the mill, the old mill had multi-story tower with seperate floors for grinding grain, removing chaff, storing grain and living quarters for the worker and his family. But both the mills had a large lever at the back of the mill to adjust with the kind of work that is being done. The larger wind mills were used to produce energy to make power for their houses. These wind mills were know as wind turbines, which appeared in Denmark in the early 1890




Current wind power plants can generate electricity for under 5 cents/kWh (kilowatt-hours), an 80% decrease from the prices 20 years ago. The prices of this can vary from place to place though, depending on a few important factors. The larger the wind farm, the lower the prices of energy will be. Wind speeds at the building site also effect prices. Higher wind speeds mean lower energy costs. These two factors effect how much it will cost to install the turbines, and the lower the cost of the turbine, the lower the cost of energy. The size of the wind farm also has a major affect on the pricing of energy. A 3 MW wind project costs $0.059/kWh, while a 51 MW wind project only costs $0.036, an almost 40% drop.

Small wind turbines for home use can also be used, and can lower electricity bills by 80-90%. An average home uses around 9,400 kilowatt-hours a year, and with a home turbine, electricity bills can be only a few dollars a month. To meet a goal such as this, a home turbine must generate at least 5 to 15 kilowatts, and be in a generally windy area.

Small Home Turbine
Small Home Turbine

Different types of wind turbines can have slightly varied prices. There are two main types of wind turbines: horizontal axis, and vertical axis. Horizontal axis turbines, being more efficient, can cost slightly more than vertical, which produce slightly less energy and are less reliable.

Most modern commercial wind turbines are 20 MW (megawatts) in size and cost about $3.5 million to install. Compared to most other modern energy sources, wind power can be the cheapest to create and provide, but is not one of the most reliable, as turbines often break down or stop working in the rain, snow and other harsh weather conditions.

As of 1992, a tax on wind energy was put into place in the Energy Policy Act of 1992. There is a 1.5-cent per kilowatt-hour production tax on wind power.

wind_turbine2(1).jpgexternal image wind-turbine.jpg






Engineer:Ashley Watts

A wind energy system transforms the kenetic energy to mechanical or eletrical energy.Mechanical energy is most commonly used for pumping water into ruralor remote locations (the farm windmill). It can also be used for many other things(grinding grain, sawing, pushing a sailboat etc.) Wind electrical turbines generate electricity for homes and businesses. There are two basic designs of wind electrical turbines: vertical-axis(egg-beater) and horizontal-axis(propeller-style.) Horizontal is the most commonly used turbines today.

Turbine subsystems include:
  • a rotor, or blade, which convert 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.
  • some turbines do not require a gear box.


Rotor (meters)
Rating (KW)
Annual MWh
The electricity generated by a utility-scale wind turbine is normally collected and fed into utility power lines. There it is mixed with electricity from other power plants and delivered to utility costumers. In August 2005 turbines with capasities as large as 5,000 kW (5MW) were being tested

What are wind turbine made of?

The towers are mostly tubular and made of steel. The Blades are made of fiberglass-reinforced polyester or wood-epoxy.

How big is a wind turbine?

Utility-scale wind turbines for land-based wind farmes come in various sizes, with rotor diameters ranging from about 50 meters to about 90 meters and with towers roughly the same size. A 90-meter machine, with a 90-meter tower would have a total height from the tower base to the tip of the rotor of approximately 135 meters(442 feet) Offshore turbine designes from 2005 showed they would have larger rotors. While they were being built the largest had a 110 meter rotor diameter. Small wind turbines intended for residential or small buisness use are much smaller. Most have rotor diameters of 8 meters or less and would be mounted on towers of 40 meters in height or less.
residential turbine

Local Expert: Danielle McGeehan
There are many pros and cons of having wind farms such as:
- they do not use anything that pollutes the air like green house gases
- they convert kinetic energy to mechanical which is out through a genarator and made into electricity
- horizontal blades can produce energy in fast or slow velocites
- the equipment is not high matinence
- aren't loud
- it affects birds that migrate
- the cost has gone up over the years
- the zoning laws of your state or municipal
- repiars can cost a lot



A wind turbine works by the blades which are connected to a rotor and produces energy. The blades spin a shaft that are connected to a genorator that produces the energy.The operation of a wind turbine is opposite of a fan.
The blades are shaped so they turn which spind different parts and catches wind or energy and turns it into electricity. A rotor which is inside copper wire spins and makes the electrical which will go through a system to be put into a building such as a house. To operate a wind turbine you would need about 10 mph of wind speed. Most turbines should last about 20 to 25 years. The picture below shows the inside of a tubine.

There are many wind farms in Pennslyvainia such as the one at Bear Creek or Waymart. The Bear Creek wind farm is Pennslyvainia's newest farm. It makes about 75 million killowatt-hours of energy annually. The Bear Creek wind farm has 12 turbines. The Waymart wind farm is the largest farm in Pennslyvania and second largest east of Mississippi river. It genorates enouch electricity to power 22,000 homes. Pennslyvania has wind farms such as Meyersdale and Mill run. Meyersdale produces about 30 MW of energy and powers about 10,000 homes. Mill Run powers about 5,000 homes.