How do Wind Turbines Work?

Summary

This script explores the concept of wind as moving air, its creation due to uneven heating of Earth's surface, and its historical use in windmills and ships. It delves into modern wind turbines, explaining how they convert wind's kinetic energy into electricity. The script details the parts of a turbine, their functions, and the physics behind energy conversion, emphasizing wind's advantages as a renewable, low-impact energy source.

Takeaways

• 📝 Wind is the movement of air, caused by the uneven heating of the Earth's surface by the Sun.
• 💻 Historically, people have harnessed wind energy for over 5000 years, starting with the ancient Egyptians using wind to sail ships.
• 💵 Windmills were initially used for grinding grains and have evolved into modern wind turbines that generate electricity.
• 💲 Wind turbines convert the kinetic energy of wind into electrical energy and come in various sizes for different applications.
• 💴 Large wind turbines, known as wind farms, are a significant source of renewable energy and are used to reduce reliance on fossil fuels.
• 💰 Wind energy has the lowest relative greenhouse gas emissions, least water consumption, and favorable social and economic impacts compared to other energy sources.
• 💵 The main parts of a wind turbine include blades, rotor, tower, pitch mechanism, low-speed shaft, high-speed shaft, gearbox, generator, brake, anemometer, controller, and yaw drive.
• 💲 The blades of a wind turbine have a wing-like profile that generates lift when pitched into the wind, capturing energy efficiently.
• 💰 The gearbox increases the rotational speed from the low-speed shaft to the high-speed shaft, which is necessary for the generator to produce electricity.
• 💴 The pitch mechanism adjusts the angle of the blades to control the rotor speed and prevent damage in high winds.
• 💲 According to Betz's law, no wind turbine can capture more than 59.3% of the kinetic energy in the wind, as extracting more would require the wind speed downstream of the turbine to be zero, which is impossible.

Q & A

What is wind?

Wind is moving air, which is invisible but can be observed through its effects on objects like leaves, grass, flags, and laundry on a clothesline.

How is wind created?

Wind is created by the uneven heating of the Earth's surface by the Sun, as different types of land and water absorb heat at different rates.

How have people used wind energy historically?

Ancient Egyptians used wind to sail ships on the Nile River over 5000 years ago. Later, windmills were built to grind grains, and in Holland, they improved windmills with propeller-type blades.

What are the modern uses of wind energy?

Modern uses include wind turbines that convert wind's kinetic energy into electrical energy, used for applications like battery charging, domestic power supply, and large-scale electricity generation in wind farms.

What are the environmental benefits of wind energy compared to other energy sources?

Wind energy has the lowest relative greenhouse gas emissions, the least water consumption, and the most favorable social economics compared to photovoltaic, hydro, geothermal, coal, and gas.

What are the main parts of a wind turbine?

The main parts include the blades, rotor, tower, pitch mechanism, low-speed shaft, high-speed shaft, gearbox, generator, brake, anemometer, controller, and yaw drive.

How do wind turbine blades generate electricity?

The blades have a wing profile that generates lift when the wind blows over them, causing the rotor to spin and the generator to produce electricity.

Why do wind turbine blades need to be pitched?

Pitching the blades adjusts them into the wind to control the rotor speed and prevent damage from winds that are too high or too low to produce electricity efficiently.

What is the role of the tower in a wind turbine?

The tower, made from tubular steel, concrete, or steel lattice, supports the turbine structure and allows it to capture more energy from higher wind speeds at greater heights.

How does a wind turbine convert wind energy into electrical energy?

The wind turns the blades, which spin the rotor connected to a generator. The generator then converts the mechanical energy into electrical energy.

What is Betz's law and what does it state about wind turbines?

Betz's law states that no turbine can capture more than 59.3% (or 16/27ths) of the kinetic energy in the wind. As the wind turbine extracts more energy, the wind is slowed down.

How do wind turbines measure and respond to changes in wind speed and direction?

Anemometers measure wind speed, and wind vanes measure wind direction. This data is sent to a controller, which adjusts the yaw mechanism to orient the turbine with respect to the wind and the pitch mechanism to control rotor speed.

Outlines

00:00

🌬️ Understanding Wind and Wind Energy

Wind is the movement of air, which is invisible but can be observed through its effects on objects like leaves, grass, flags, and laundry. It is created by the uneven heating of the Earth's surface by the Sun, leading to air motion. Historically, wind has been harnessed for sailing and milling grains, with the Dutch improving windmill design. Modern applications include wind turbines that convert wind's kinetic energy into electricity. These turbines come in various sizes and are part of wind farms that contribute to renewable energy strategies, reducing reliance on fossil fuels. The script explains the components of a wind turbine, including blades, rotor, tower, pitch system, low and high-speed shafts, gearbox, generator, brake, anemometer, and yaw drive, and how they work together to generate electricity.

05:01

💡 The Mechanics of Wind Turbines

Wind turbine blades are designed with an aerodynamic profile similar to airplane wings, which generates lift when pitched correctly into the wind. The airflow direction is a combination of the wind and the rotation-induced airflow. The blade tips can reach high radial velocities, necessitating a twist to maintain the optimal angle of attack for energy capture. The slow rotation speed of the blades is increased by a gearbox to generate electricity. A brake system is included to prevent damage from high winds. The electricity is transmitted through cables to a transformer at the tower's base. Wind direction is monitored by an anemometer and wind vane, with a yaw system ensuring the turbine faces the wind for maximum efficiency. The pitch system adjusts the blades to maintain alignment with wind changes. Betz's law is introduced, stating that no turbine can capture more than 59.3% of the wind's kinetic energy, as extracting more would require the wind speed downstream of the turbine to be zero, which is impossible.

10:03

🔢 Betz's Law and Wind Energy Conversion

This paragraph concludes the discussion on Betz's law, which limits the maximum theoretical efficiency of a wind turbine to 59.3%. It explains that as a turbine extracts kinetic energy from the wind, the wind speed downstream of the turbine decreases. The law is proven by calculating the power extracted from the wind and comparing it to the power in the undisturbed wind. The maximum power extraction occurs when the downstream wind speed is one-third of the upstream speed.

Keywords

💡Wind

Wind is defined as moving air, which is invisible but can be observed through its effects on objects such as leaves, grass, and flags. In the video, wind is the primary subject, as it discusses how wind is created and harnessed for various purposes. The script mentions that wind is caused by the uneven heating of the Earth's surface by the Sun.

💡Wind Energy

Wind energy refers to the process of capturing the kinetic energy of wind and converting it into other forms of energy, such as electricity. The video script explains how wind energy has been harnessed since ancient times, from sailing ships to modern wind turbines, emphasizing its role in renewable energy production.

💡Windmill

A windmill is a structure that uses wind to generate mechanical energy through vanes or sails. The script describes early windmills with paddle wheels and how they evolved into the iconic Dutch windmills with propeller-type blades. Windmills are historically used for grinding grains and pumping water.

💡Wind Turbine

A wind turbine is a device that converts the kinetic energy from the wind into electrical energy. The video explains that modern wind turbines come in various sizes and are used to generate electricity, either for domestic use or as part of large wind farms contributing to the power grid.

💡Renewable Energy

Renewable energy is energy that is collected from renewable resources, which are naturally replenished on a human timescale. Wind is highlighted in the script as a renewable energy source with benefits such as low greenhouse gas emissions and favorable social economics compared to fossil fuels.

💡Pitch System

The pitch system in a wind turbine is used to control the angle of the blades relative to the wind, optimizing the energy capture and protecting the turbine from high wind speeds. The script mentions that pitch turns the blades out of the wind to control the rotor speed and prevent damage.

💡Generator

A generator is a device that converts mechanical energy into electrical energy. In the context of the video, the generator in a wind turbine is driven by the rotation of the rotor to produce electricity. The script explains that the generator produces 60-cycle AC electricity.

💡Gearbox

A gearbox is a transmission device that increases the rotational speed from the low-speed shaft to the high-speed shaft. The script describes how the gearbox is used in wind turbines to convert the slow rotation of the rotor into the high speeds required by most generators.

💡Anemometer

An anemometer is an instrument used for measuring wind speed. The video script mentions that an anemometer is used in wind turbines to measure wind speed and transmit this data to the controller, which then manages the operation of the turbine.

💡Yaw System

The yaw system is responsible for orienting the wind turbine so that it faces into the wind for maximum efficiency. The script explains how the yaw system, controlled by a motor, adjusts the turbine's position based on wind direction changes detected by the wind vane.

💡Betz's Law

Betz's Law, also known as the Betz limit, states that no wind turbine can capture more than 59.3% of the kinetic energy in the wind. The script discusses this law to explain the theoretical maximum efficiency of a wind turbine and how it relates to the wind speed both upwind and downwind of the turbine.

Highlights

Wind is air in motion caused by the uneven heating of the Earth's surface by the Sun.

Ancient Egyptians used wind to sail ships on the Nile River over 5000 years ago.

Windmills were later built to grind wheat and other grains, resembling paddle wheels.

Holland improved windmills with propeller-type blades made with sails.

Windmills in the US were used for grinding wheat, pumping water, and cutting wood.

Modern wind turbines convert wind's kinetic energy into electrical energy.

Wind turbines come in various sizes for different applications, from battery charging to power supply.

Wind farms are significant sources of renewable energy, reducing reliance on fossil fuels.

Wind energy has the lowest greenhouse gas emissions and least water consumption among energy sources.

The main parts of a wind turbine include blades, rotor, tower, pitch system, and generator.

Wind turbine blades have a wing profile similar to airplanes to generate lift.

The tower of a wind turbine is made from tubular steel, concrete, or steel lattice.

Wind speed increases with height, so taller towers can capture more energy.

The pitch system controls the angle of the blades to optimize energy capture and protect from high winds.

The generator produces 60 cycle AC electricity, typically using an induction generator.

The brake system stops the turbine mechanically, electrically, or hydraulically in emergencies.

An anemometer measures wind speed, and a wind vane measures wind direction for the turbine's orientation.

Betz's law states that no turbine can capture more than 59.3% of the kinetic energy in the wind.

Wind turbines operate most efficiently when aligned with the wind direction.

The efficiency of a wind turbine is measured by comparing upstream and downstream wind speeds.

Transcripts

[Music]

what is wind wind is moving air although

you can't see the wind is so you can see

how its force affects things in its path

leaves grass Flags laundry on a

clothesline

even your hair on a windy day how wind

is created wind is simply air in motion

it is caused by the uneven heating of

the Earth's surface by the Sun because

the Earth's surface is made from very

different types of land and water

it absorbs the Sun heats at different

rates

one example of this uneven heating can

be found in the daily wind cycle

since ancient times people have

harnessed the winds energy over 5000

years ago the ancient Egyptians use the

wind to sail ships on the Nile River

later people build windmills to grind

wheat than other grains the early

windmills look like paddle wheels

centuries later the people in Holland

improved the windmill they gave a

propeller type of blades still made with

sails Holland is famous for its

windmills in this country the colonists

used windmills to grind wheat and corn

to pump water and to cut wood sawmills

today people occasionally use windmills

to grind grain mhmm water but they also

use modern wind turbines to make

electricity a wind turbine is a device

that converts the winds kinetic energy

into electrical energy wind turbines are

manufactured in a wide range of vertical

and horizontal access types the smallest

turbines are used for applications such

as battery charging for power for boats

or caravans or to power traffic warning

signs slightly larger turbines can be

used for making contributions to a

domestic power supply while selling

unused power back to the utility

supplier via the electrical grid a raise

of large turbines known as wind farms

are becoming increasingly important

source of intermittent renewable energy

and are used by many countries as part

of a strategy to reduce their reliance

on fossil fuels window is shown to have

the lowest relative greenhouse gas

emissions the least water consumption

demands and the most favorable social

economics compared to photovoltaic hydro

geothermal coal and gas

let's see the main parts of the wind

turbine blades blades lift some rotates

when the wind is blown over them causing

the rotors to spin rotor blades and hub

together form the rotor tower tower made

from tubular steel concrete or steel

lattice supports the structure of the

turbine because of wind speed increases

with height taller tower was unable to

or bias the capture more energy and

generate more electricity

pitch turns or pictures blades out of

the wind to control the road to speed

and to keep the rotor from turning in

winds that are too high or too low to

produce electricity lowest speed shaft

turns as those beat shaft at about 30 to

60 revolutions per minute

high speed shaft drives the generator

gearbox connects the low-speed shaft to

the high speed shaft and increases the

rotational speeds from about thirty to

sixty rotations per minute to about 1000

to 1800 rpm

this is the rotational speed required by

most generators to produce electricity

generator generates a producer 60 cycle

AC electricity it is usually an

off-the-shelf induction generator

brake brake stops or motor mechanically

electrically or hydraulically in

emergencies

anemometer measures the weed speed and

transmits wind speed data to the

controller controller controller start

up the Machine and wind speeds up to

about 8 to 60 miles per hour and shuts

off the machine at about 55 miles per

hour turbines to not operate our wind

speeds above about 55 miles per hour

because they may be damaged by the high

winds wind vane measures wind direction

and communicates with the yaw Drive to

orient the turbine properly with respect

to the wind your drive Orient's up wind

turbines to keep them facing when wind

direction changes down wind turbines

don't require your drive because the

wind manually blows the rotor away from

its your motor powers the yaw Drive

how the wind turbine is working let's

see the basic working when the wind is

blowing the blades are turned the rotor

is connected to the generator while it

rotates the rotator generator produces

the electricity let's get deep into the

functioning of each parts and how the

wind energy turns into electrical energy

first we will see the wind blades the

blades having the wing profile like the

airplanes the shape of the blade what

makes the wind turbines to rotate but

only if the angle of attack is right by

pitching the blade into the wind

the blade generates lift the direction

of the airflow is the combination of the

wind and the airflow caused by the

rotation of the rotor near the blade

root the radial velocity of the blade is

low but on the tip of the blade the

radial velocity of the turbine is as

high as 18 m/s this is why the tip of

the blade twisted into the direction of

the airflow ensures the right angle of

attack to harvest as much energy from

the wind as possible the wind turbine

blades typically turn at a very low rate

of rpm due to the issues of the noise in

mechanical strength at this level of

rotation we cannot produce any

meaningful electricity from a generator

we have to increase the speed of the

rotation of the generator so this setup

used by planetary gearbox to achieve a

maximum speed if wind is blowing our

high speed turbine may damage so the

brake system is placed to control the

over speed in windy days

electricity produced from the generator

passed through a cable towards the

bottom of the tower where the step-up

transformer is situated

the wind turbine should face toward the

wind for maximum power generation but

wind can change its direction at any

time anemometer and wind vane is located

at the top of the nacelle

it measures the wind speed and direction

if any changes in the wind direction it

sends to the controller the control

system controls the your mechanism to

rotate the nacelle with the help of the

your motor so the wind turbine can

always aligned with the winds direction

velocity also changing in the blades due

to the wind speed so blade tilting

mechanism is located at the rotor this

is called pitch system it tilts the

blades at corresponding direction with

proper alignment to ensure velocity to

check the efficiency of the wind turbine

measure the wind speed at upstream and

downstream over a wind turbine the wind

speed of downstream is much smaller than

the upstream this is because the blades

absorb some kinetic energy from the wind

the same amount of energy is converted

as mechanical power of the wind turbine

a wind turbine absorbs a 100 percent of

the available kinetic energy only if the

downstream wind becomes zero

however zero wind speed are downstream

is physically impossible condition

now let's see what is Betts's law about

the wind turbine according to Betsy's

law no turbine can capture more than 16

twenty-seventh that is 59.3%

of the kinetic energy and wind the more

kinetic energy our wind turbine pulls

out of the wind the more the wind will

be slowed down as it leaves this is

called Betts's law let's prove this

theory let's assume the average wind

speed through the rotor area is the

average of the undisturbed wind speed

before the wind turbine chord is v1

and the wind speed after the passage

through the rotor playing chord as V 2

that is V 1 plus V 2 divided by 2

the mass of the air streaming through

the rotor during one second is equal to

the multiplication of the density of

their swept area around the drove the

average wind speed through the rotor

area according to Newton's second law

power extracted from the wind by the

rotor is equal to the mass times the

drop in the wind speed squared

substituting em into this expression

from the first equation we get the

following expression for the power

extracted from the wind now let us

compare our results with the total power

in the undisturbed wind streaming

through exactly the same area F with no

rotor blocking the wind be cool this

power p0 the ratio between the power we

extract from the wind and the power in

the undisturbed wind is then P divided

by p0 equals 1 over 2 times 1 minus v2

divided by v1 all squared times 1 plus

v2 over v1

we may plot P divided by p0 as a

function of V 2 divided by V 1

we can see that the function reaches its

maximum for v2 divided by v1 equals one

third

and that the maximum value for the power

extracted from the wind is zero point

five nine or sixteen over twenty-seven

of the total power in the wind