WIND POWERPORTER WESSON

WIND GENERATORS-A wind generator (wind turbine) works by capturing kinetic wind energy and converting it to electrical energy.

-Wind turbines are used for different purposes based mainly on their size

Large turbines in “wind farms” produce electricity for cities.

Smaller turbines contribute energy to a community and sell extra energy back to the energy supplier.

Small-scale turbines are used to charge batteries.

How it all works For a conventional horizontal-axis turbine:

Three wing-shaped blades are positioned facing horizontal to wind.

The blades create lift and spin. Blades spin a rotor connected to a low-speed

shaft. Low speed shaft rotates between 30 and 60

rpm. Gear box connects low-speed shaft to high-

speed shaft. High speed shaft rotates between 1000 and

1800 rpm. High-speed shaft spins the generator.

Advantages & Disadvantages Advantages:

Energy produced is: Clean

Domestic

Sustainable

One of the cheapest renewable energy sources.

Isn’t a large disruption to the terrestrial environment.

Can be land, ocean or air based.

70-85% efficient.

Disadvantages: Requires higher initial

investments then non-renewable energy sources and is sometimes not cost effective.

Places that need energy don’t have good wind.

Auditory and visual concerns.

Potential hazard to avian environment

Terrestrial turbines only generate about 30% of their capacity factor. Off-shore is higher.

Disadvantages continued:Fairly self-explanatory…

Restricting factors: Only spin at wind speeds higher

than roughly 8mph.

Shut down at wind speeds greater than roughly 55mph due to the compromising of structure strength.

Generates peak power between the range of 25-55 mph.

Highest and most consistent wind speeds are generated at high altitudes.

Highest density air is found at low altitudes.

Wind Power Classification:

Other kinds of wind turbines:Vertical axis turbines

Different designs:

Wind Power Development:

Other developments:

The math behind it all: The energy produced by a traditional horizontal axis turbine

is given by the equation

Kinetic energy per unit time (Ek/s) = ½ pAv3

p = air density in Kg/m3 A = turbine blades “sweep area” given by using the

formula for area of a circle. v = velocity of wind. Found by subtracting the velocity of

the wind after passing through the turbine by the initial velocity of the wind. Given in m/s.

This equation is for the potential amount of power the turbine can generate. Since it is impossible for a turbine to perform at 100% efficiency, this equation only gives a theoretical answer.

PUT IT TO WORK!!!

1) How much power does a wind turbine with a blade length of 35 meters (which is typical industrial turbine size) snag from the windy wind moving at an initial velocity of 18 m s-1 with a constant density of 1.4 kg m-3 ? The velocity of the air immediately after passing through the turbine sweep area is 13 m s-1.

PUT IT TO WORK AGAIN!!!

2) DUH!! Wind turbines aren’t 100% efficient! Estimating that the efficiency of this turbine is 75%, calculate the electrical power created by the generator.

YOU BETTER HAVE DONE IT RIGHT!!!

1) 1.3 X 104 kW

2) 1.0 X 104 kW

WORKS CITED:

http://energy.gov/eere/wind/how-do-wind-turbines-work

http://environment.nationalgeographic.com/environment/global-warming/wind-power-interactive/

http://www.alternative-energy-news.info/technology/wind-power/wind-turbines/

http://www.reddit.com/r/worldnews/comments/1byje4/ontario_is_putting_an_end_to_coalburning_power/

http://www.smartplanet.com/blog/thinking-tech/wind-powers-future-may-soar-with-flying-wind-turbine/

http://www.globalwindday.org/faqs/how-efficient-are-wind-turbines/