How a Wind Turbine Works

How a Wind Turbine Works

Learning how a wind turbine works is easy as long as you first make sure to know how a turbine generator works.

The diagram of the wind turbine above is a side view of a horizontal axis wind turbine with the turbine blades on the left.  Most modern wind turbines are built with a horizontal-axis similar to the one seen in the figure.

The figure is also a common up-wind turbine, meaning that the for the turbine to perform effectively, the nose and blades of the turbine should be facing the wind.

To learn more about how wind turbines work, one can start by looking at the diagram above and study each component of a wind turbine.

Step-by-step look at each piece of a wind turbine from diagram above:

(1)  Notice from the figure that the wind direction is blowing to the right and the nose of the wind turbine faces the wind.

(2)  The nose of the wind turbine is constructed with an aerodynamic design and faces the wind.

(3)  The blades of the wind turbine are attached to the nose and the rotor and begin to spin in ample wind speeds.

(4)  The main turbine shaft is what connects the spinning blades to the inner workings of the machine.  The turbine shaft spins with the blades and is the mechanism that transfers the rotational/mechanical energy of the blades towards the electrical generator.

(5)  A brake is installed to prevent mechanical failure from high wind and high rotational speeds.  It can also stop the turbine when it is unneeded.

(6)  The gearbox is used to increase the rotational speed of the turbine shaft.  The gearbox works like the gears on a bicycle, as the gears change, the rotational speeds will change too.  Then, it transfers the rotational energy into the high-speed turbine shaft and into the generator.

(7)  The high-speed turbine shaft connects the gear box and the generator.  It’s high rotating speeds are what spin the turbine generator.

(8)  The turbine generator is the most essential part of how a wind turbine works.  The turbine generator is what converts the mechanical energy from the wind into electrical energy using the rotating force that is transferred from the gears and turbine shaft.

(9)  The anemometer is a device that measures wind speeds.  They are usually installed to instruct the controller to stop or start the turbine in certain wind speed conditions.

(10)  The controller is installed in case the wind speeds reach an undesired speed, the anemometer can instruct the controller to use the brake and stop the rotating blades.  The controller is also used to help start spinning the blades and rotor in low wind speeds.

(11)  The wind vane is an instrument that measures the direction of the wind.  The wind vane is important for up-wind turbines that need to be facing the wind in order to operate properly.

(12)  The yaw drive in the mechanism that receives data from the wind vane and instructs the wind turbine to rotate to be facing the wind.

(13)  The yaw motor is the device that physically rotates the turbine to be facing the wind or as instructed by the yaw drive.

(14)  The turbine tower contains wiring so the generator can send electricity into a transformer or a battery which will eventually distribute usable electric power.  The tower is also a crucial structural support system that holds the turbine high in the air where wind speeds are more desirable.

(15) How a wind turbine works well outside, and during intense wind speeds is because all of the components are built at the top of the turbine tower and placed safely inside the turbine nacelle.  The tower and the nacelle of a wind turbine are usually made out of cylindrical steel and can either be supported by guy wires and guy tensions or stand alone using a lattice standing base.

Again, this diagram shows an example of an up-wind, horizontal axis wind turbine that may be made of steel and potentially stand several stories tall.  How a wind turbine works not only involves great engineering, it also requires thoughtful analysis and strategy to find desirable locations with ample wind speeds.

How Much Energy do Wind Turbines Produce?

In 1919, German physicists Albert Betz discovered that no wind turbine could physically capture more than 59.3% of the kinetic energy of the wind.  A simple way to explain this is that if a wind turbine ever captured 100% of the wind, there would be no wind passing through the other side of the wind turbine blades.  If there is no wind passing the other side, then according to the physical law of wind movement, there would be no room for any more wind to pass through the front of the wind turbine, rendering the wind turbine useless.

So, to calculate wind power output or the amount of wind electricity that is expected to be produced from a wind turbine you will need a short list of dependent variables:

                       (Cp) – Turbine efficiency coefficient, maximum of 0.593

                        (ρ)  -  Air Density, measured in pounds/cubic foot

                        (A)  -  Area of rotor blade, measured in square feet

                        (V)  -  Wind Speed, miles/hour

                        (k)  -  k is a constant that equals 0.000133, this coverts the answer into kilowatts

                        (P)  -  Power Output, the independent variable we wish to calculate, in kilowatts

With the above variables, the equation to calculate the wind electrical output of a wind turbine is:

P = k * Cp * (1/2) * ρ * A * (V^3)

Note the relationship of each variable from the equation and how it relates to how a wind turbine works. The area of the rotor blade (A) has a direct positive relationship with power output, and wind speed (v) has a positive cubic relationship with power output.

The amount of electricity that a wind turbine can generate depends mostly on the size of the turbine, the area swept by the turbine blades, the air density, and the wind speed.  The overall design of the wind turbine is also crucial for how efficiently the blades can capture the wind.

Smaller wind turbines used for boats, caravans, or smaller machines generally produce around 250 watts to 100 kilowatts of wind electricity. Some of the biggest wind turbines in the world produce around 7 megawatts of electricity.

It is important to remember that wind speed is not constant, so the theoretical output of electricity that a wind turbine can produce is a maximum potential of energy output that is rarely reached.  The actual energy produced from a wind turbine, when stated in a ratio with the theoretical expectations of the wind turbine is called the capacity factor.

A 10 kilowatts wind turbine in an area with about 12 mph wind speeds would produce about 10 kilowatt-hours of wind electricity a year, which is around the amount needed to supply electricity to an average household.

A 5 megawatt wind turbine could produce around 15 million kilowatts hours of wind electricity in one year, which could provide power to over 1,000 households.

Conclusion:  A wind turbine only operates when the wind is blowing, and understanding how a wind turbine works means understanding the aerodynamics of the wind and blades, while also knowing how a turbine generator creates electricity.  At its most fundamental roots, a wind turbine works by allowing wind to rotate a turbine generator.