Energy Unit if 3 ESO Technology

Unit 5. Energy

Unit 5. Energy

5.1 Energy

1.1Units

1.2 Forms and Sources

5.2 Electric energy

2.1 Generation

2.2 Main Power Stations

2.3 Distribution

5.3 Consume

5.1.1 Energy. Units

Energy is the capacity of an object to do a work.

And work is the force applied along a distance

5.1.1 Energy. Units

In physics we define mechanical work as the amount of energy transferred by a force acting through a distance

W= F•dd= distance between A and B

F= Force applied to move the object

F

d

5.1.1 Energy. Units

Therefore, in this example, the energy that black cartoon has, the express the work that can apply to this box,

5.1.1 Energy. Units

UnitsThere are several units of energy that are used in special areas, the most popular are the j, cal and kwh.

Joule calorie kwh

5.1.1 Energy. Units

Joule (J) is the International System’s unit for work, and is usually expressed in Kj.

1kj is the energy need to raise 100kg 1 meter high

1 meter

5.1.1 Energy. Units

Calorie (cal) This unit is usually used to express energy that involves calorific transference. When energy is used in the alimentary industry, it’s usually express in Kcal.In the USA, they write Cal instead of Kcal…

In order to heat 1 L of water from 20 to 21 ºC we need 1kcal

5.1.1 Energy. Units

A human being needs around 2000 kcal per day of energy to do all the work that it needs.

5.1.1 Energy. Units

When you drink a Coke you are absorbing 139 Kcal of energy that is stored in the 39gr of sugar dissolved in the liquid.

139 Kcal 420Kcal 840Kcal

Investigate the energy that these foods have per 100 gr:

Yogurt Big Mac

Bread Apple

Biscuits Orange Fanta

Cereals Oil

Chips Butter

Solution

5.1.1 1º Exercise

5.1.1 Energy. Units

KiloWatt/hour(kwh) It’s the unit used to measure the electric consumption of an electric installation.

When we use a hairdrier of 1000 W for 1h, we have consumed 1 kwh

5.1.1 2º Exercise

Conversion units1Kwh= 1000Wh1 W= 1 j/s1calorie= 4,18 joules

2º Exercise:•Calculate the energy of a Coke in joules.•Calculate the energy measured in kwh that we absorb in 2h when we drink 2 Cokes?•If we use a 100W lamp, and we use Cokes to provide energy, how many Cokes do we need per second?

Solution

5.1.2 Forms and Sources

So Energy is the capacity of an object to do a work, and it can be stored in different forms of enery:

Calorific energy

Light energy

Mechanical energy

Electrical energy

Electric energy

Chemical energy

Nuclear

energy


The law of conservation of energy expresses that can neither be created nor destroyed, it can only be transformed from one state to another

Calorific energy

Light energy

Mechanical energy

Electrical energy

Electric energy

Chemical energy

Nuclear energy


In order to obtain energy we have to use the different energy sources present in Earth: oil, coal, wind, uranium, etc.


We can classify the energy sources according to its:

Origin: Renewable or Non Renewable

Historical use: traditional or alternative

Transformation: Primary or secondary


3º Exercise:a)Explain the difference

between the concepts of source and form of energy.

b)Define the six groups of energy sources, and give four examples of each.

solution


Origin: a)Renewable : These sources are

Inexhaustible, therefore we can use them continuously. For example: Wind, Waves, etc…


Origin: .a)

b)Non Renewable : These sources are exhaustible, therefore we consume the source when we use it. For example: oil, Uranium


Historical use: a)Traditional: these sources have

been used for at least 30 years, and they provide more than the 90% global energy. They are:

Hydraulic, Coal, Oil, Gas, Uranium


Historical use: a)Traditional

b)Alternative: these sources can provide energy but they can’t displace the alternative energy because they are cheaper or easier to obtain. For example

Solar Wind bio-mass Wave Geothermal


Transformation: a)Primary: These sources are

obtained directly from the environment and they can be used directly without any transformation.

For example: Hydraulic, Coal, Oil, Gas, Solar Wind bio-mass Wave Geothermal


Transformation: a)Primary: b)Secondary: These sources are obtained

after the transformation of a primary source. We use them because they are cleaner or easier to use

For example: Electricity, Oil derivatives (Gasoline, Diesel, etc), Town

Gas

5.1.2 exercise 5Forms and Sources

5º Exercise: Make a list of 20 objects indicating the form of energy used and the energy obtained .

For example: TV-Electricity

Object Energy Form Energy obtained

TV Electricity Light

. . .

. . .

. . .

Sol

Electricity production.

Why do we like Electricity so much?

5.2.1 Electric energy. Generation

Electricity is the principal source of energy in the developed homes and in industries because it’s the cleanest and most versatile energy.

5.2.1 Exercise. Electric energy. Production1º Exercise:Compare the use of electricity at home with the use

of coal, oil, gas, solar, wind, geothermal, uranium.2º Exercise:What do we mean when we say that the electricity is

clean?

Solution

As we know, if we want to create an artificial electric current, we only need:

A closed circuitAn artificial magnetic fieldA mechanical energy to move the

circuit inside the field.


When we have all elements together, we find that we create an alternate electric current due to the movement of the spiral.


The only difference between power stations is how they get the energy to move the turbine that moves the circuit inside the generator

5.2.2 Electric energy. Power Stations

Generatorturbine

One big group of use different sources to HEAT water and create steam to move the turbine


turbine

steam

Other small group use the primary source to move the turbine, using water or wind


In conclusion we will always find these elements in a Power Station:


Mechanical Energy

GeneratorTurbine

Electric generation Electric

Transformation

Electric Transport

Transformer

PrimaryEnergy

Electric Transport

And this is the summary of the production in a block diagram


Mechanical EnergyWater or

Air

Steam from a

combustion, nuclear

reaction, solar or geothermal

Electric generation

Electric Transformation

Turbine

Generator

Transformer

PrimaryEnergy

POWER STATIONS

Steam

Turbine

Generator

Transformer

Mechanical Energy

Ele

ctric

ity

Pylon

Hig

h V

olt

All Power stations will have this elements, now we will see how they move the turbines

Water, Wind


Steam Power Station Diagram5.2.2 Electric energy. Power Stations

Steam

Boiler

Turbine

Generator

Transformer

Cooling

Mechanical Energy

Ele

ctric

ity

Cold Water

Heat

Pylon

Hig

h V

olt

Ste

am

We use the energy source to create steam pressure to move the turbine

Turbine

Generator

Transformer

Mechanical Energy

Ele

ctric

ity

Pylon

Hig

h V

olt

We use the primary Energy like wind or water pressure to move the turbine


Wind

Water

Coal power Station5.2.2 Electric energy. Power Stations

Steam pressure

Coal power Station Diagram5.2.2 Electric energy. Power Stations

Steam

Mine Furnace

Boiler

Turbine

Generator

Transformer

Cooling

Mechanical Energy

Ele

ctric

ity

Cold Water

Heat

Pylons

Hig

h V

olt

Ste

am

Coal

9º Exercise. Draw the diagram of all Power Stations as

we have seen in the Coal Station Diagram


Coal power StationAdvantages

Inexpensive compared to other energy sources

Coal is present in most of the countries, so they don’t have to buy it abroad

By-product of burning, ash, can be used for concrete and roadways

Disadvantages

Limited supply, non-renewable resource. 100 years

The Carbon dioxide generated increase the effect of the global warming. Generated smoke can cause health conditions such as emphysema

Sulphur dioxide and nitrogen emissions can bind to water creating acid rain

Coal mining mars the landscape


Nuclear power station5.2.2 Electric energy. Power Stations

Diagram

Infografía

Nuclear power stationAdvantages

Worldwide nuclear energy avoids on average the emission of more than two billion metric tones of carbon dioxide per year, decreasing the effect of the global warming.

Although nuclear power reactors are expensive to build, they are relatively cheap to operate.

It is possible to generate a high amount of electrical energy in one single plant.

Disadvantages

The waste from nuclear energy is extremely dangerous and it has to be carefully looked after for several thousand years .

Despite a generally high security standard, accidents can still happen.

Nuclear power plants as well as nuclear waste could be preferred targets for terrorist attacks.

Is a non renewable source. 50 years


Hydro Power Station5.2.2 Electric energy. Power StationsDiagram

Primary Energy


Hydro Power StationAdvantages

When the electricity is generated, no greenhouse gases are made.

Water is a renewable energy source and free.

We create huge potable water deposits.

Disadvantages

The dam is expensive to build and the nearby area has to be flooded

In drought season we may not have enough water to turn the turbines.

Solar Power Tower Plant5.2.2 Electric energy. Power Stations

Diagram

Steam pressure

Solar photovoltaic Plant5.2.2 Electric energy. Power Stations

Diagram

Solar Energy

Advantages

Inexhaustible fuel source

No greenhouse gasses emited

Versatile since it is used for powering items as diverse as solar cars and satellites

Disadvantages

It does not work at night.

Very diffuse source means low energy production.

Only areas of the world with lots of sunlight are suitable for solar power generation

They need great lands creating high temperatures below the panels


Wind Plant

5.2.2 Electric energy. Power Stations Diagram

Primary Energy

Wind PlantAdvantages

It is available over a greater area than occurs with fossil fuels.

There is no air pollution after manufacture.

Modern wind energy converter systems can be set up for individual houses.

Wind energy produces more energy per area of land than other energy sources.

Disadvantages

Modern wind energy systems are expensive, although the source is free.

They can be rather ugly or the noise of the rotor could be annoying if the installation is located close to homes or workplaces.

The wind does not blow all the time.

Potential TV interference caused by rotor.



Tide Energy Diagram

Primary Energy

5.2.2 Electric energy. Power StationsTide EnergyAdvantages

Tides are free once the power station has been built and will not run out.

No greenhouse gases are produce.

We know exactly when the tides happen so we know when electricity will be made.

Disdvantages

Dams may not be good for plants and animals that live nearby.

The tides only happen twice a day, so can only produce electricity for that time.


Wave Energy

Primary Energy

5.2.2 Electric energy. Power StationsWave EnergyAdvantages

Waves are free and will not run out so the cost is in building the power station.

Wave power does not produce greenhouse gases.

There are very few safety risks with wave power generation.

Disdvantages

Waves can be big or small so you may not always be able to generate electricity.

You need to find a way of transporting the electricity from the sea onto the land.

Not many people have tried to generate electricity this way yet so the equipment is expen-

sive.


Biomass.

Naturalbiomass

Dry BiomassWaste from industrial process

Wet BiomassHuman or animal disposal

EnergeticCropsHigh Energy PlantsAre cultivated

Diagram

Steam pressure


BiomassAdvantages

The fuel is cheap and can use things that we might otherwise throw away.

We can find waste everywhere and should not run out.

Disadvantages

When the fuel is burned greenhouse gases are made which pollute the environment.

Sometimes people grow biomass crops where we could grow food.

We may not have enough space to grow enough biomass fuel.


Geothermal EnergyDiagram

Steam pressure


Geothermal EnergyAdvantages

Geothermal energy does not produce greenhouse gases

The energy source is free and will not run out

Disadvantages

There are not many places where we can build geothermal power stations

Harmful gases and minerals may occasionally come up from the ground below. These can be

difficult to control.

5.2.2 Electric energy. Power StationsFusion Energy the Future Energy

Steam pressure


Source Renowable/ Non reno.

Type of central

Advantages Disavantages

Wind

Thermical

Water

Radioactive waste

Tide

Once we create electricity we have to transport it to the final users. Nowadays we use these elements:

5.2.3 Electric energy. Distribution

Transformer

Pylons

Transformer

Final User

Why do we need a transformer???


All conductors have resistance, and its opposition to the intensity creates HEAT !!!


so our electric distribution could be a huge heater!!!!

P=I2R

Therefore, in order to transmit high electric power, we have to decrease the intensity by increasing the voltage


So, with high voltage distribution, we lose less calorific energy and thanks to that we can use thinner cables

V

PI VIP

But, how does it work?5.2.3 Electric energy. Distribution

Any transformer is based in the relation between the magnetic field created by two reels that have the same nucleus


Nucleus

Reel Reel

This is the relation between the I and V in each Reel:


Nucleus

Input Output

N

N

I

I

V

V

2

1

1

2

2

1

V1 V2

We want V2 as high as possible so we have to increase the number of spirals of the 2º reel (N2) and decrease on N1


€

V1

V2

=I2

I1

=N1

N2

⇒ V1 N2

N1

=V2

N2 ↑⇒ V2 ↑

Exercise 5.2.3. Calculate the V2, before and after we increase the number of spirals. I= 20A


€

N1 = 20

N2 = 40 before and after N2 = 200

V1 = 400V

Lets calculate V2 5.2.3 Electric energy. Distribution

€

V1

V2

=I2

I1

=N1

N2

⇒ V1 N2

N1

=V2

V2 =V1 N2

N1

=400 × 40

20

V2 = 800V N2 ↑⇒ V2 ↑

€

V2 =V1 N2

N1

=

V2 =400 × 200

20

V2 = 4000V

Before After

Lets calculate V2 5.2.3 Electric energy. Distribution

€

V2 = 800V P = VI

I2 = 20A P = 800 × 20

P =16000W

Before After

€

V2 = 4000V P = VI

I2 = 20A P = 4000 × 20

P = 80000W

Electricity arrives at home trough the electric panel that we find close to the entrance door


Electric meter

HOME

Basic electric panel

High electric panel

In the control panel we find:1º The ICP: This circuit break is placed

by your electric company to control that you don’t pass the top consume that you have contracted


In the control panel we find:1º The IGA: This circuit break

allows us to break the hole circuit with one switch


In the control panel we find:1º The Differential switch : This

circuit break protects us against a electric discharge


In the control panel we find:1º PIA: These circuit breakers

control the different circuits that we have at home


5.3 Consume

In Spain, we use too much fossil energy to produce electricity

5.1.3 Consume

These

are

the m

ain

centr

als

in S

pain

5.3 Consume

This is the evolution of the self energy supply for the last 35 years

YearSelf energy Supply

1975 22,6

1985 38,9

1995 28,0

1998 25,6

2003 22,1

2008 21,6

Fuentes: 1975-1998:,[6] 2003:[7] 2008: Ministerio de Industria, Turismo y Comercio[1

5.3 Consume

This is the use of the different forms of energy.

Fuente de energía

Producción 2007 (ktep)

2007 %Producción 2008 (ktep)

2008 % 2008/2007

Carbón 5.865 19,3 4.374 14,2 -25,4

Petróleo 143 0,5 127 0,4 -11,2

Gas natural 16 0,1 14 0,0 -10,9

Nuclear 14.360 47,3 15.368 50,0 7,0

Hidráulica 2.342 7,7 2.001 6,5 -14,5

Otras energías renovables

7.624 25,1 8.841 28,8 16,0

Total 30.348 100,0 30.725 100,0 1,2

5.1.1 1º Exercise Solution

Yogurt 85 kcal Big Mac 498 kcal

Bread 250kcal Apple 59 kcal

Biscuits 450 kcal Orange Fanta

58 kcal

Cereals 400kcal Oil 900kcal

Chips 234kcal Butter 760 kcal

Investigate the energy that these foods have per 100 gr:

Solution

5.1.1 Energy. Units

2º Exercise Solution:•Calculate the energy of a Coke in joules.

•Calculate the energy measured in kwh that we absorb in 2h when we drink 2 Cokes?

jcal

j57684018,4138000cal

138000cal138Kcal

€

138Kcal

1Coke= 576,84

kj

1Coke ⇒ 576,84

kj

1Coke⋅

1h

3600s= 0,16

kjh

s= 0,16

Kwh

1Coke

0,16kwh

1Coke⋅ 2Cockes = 0,32kwh

5.1.1 Energy. Units

2º Exercise Solution:•If we use a 100W lamp, and we use Cokes to provide energy, how many Cokes do we need per second?

s

Coke

js

jCoke

Cokej

sj

kcal

kj

31073,1576840

100576840

100s

j100100W

Coke

j57684048,1

Coke

Kcal138

Exercise

5.1.2 3 Exercise Forms and Sources3º Exercise:a) Explain the difference between the concepts of source and form of

energy.The source of energy is how we get energy, for example the coal or wind; and

the form of energy is the type of energy, for example mechanical or nuclear energy.

Or more detailedBoth terms are related to energy. Energy is the capacity of an object

to do a work, and it can be stored in different forms of energy, like electric, chemical, mechanical, etc.

A source of energy is how this form of energy is stored for its use around us. A form of energy is a energy resource, i.e. wind, sun light, etc.

So, coal is a source of energy because it store a lot of useful chemical energy liberated when we burn it

5.1.2 3 Exercise Forms and Sources3º Exercise:a) Define the six groups of energy sources, and give four examples of

each. Define the six groups of energy sources, and give four examples of each.

Renewable (Origin): Inexhaustible sources which can be used continuously. Ex: Wind, waves, sun and firewood.

Non renewable (Origin): Exhaustible sources which can be exhausted as years go. Ex: Oil, uranium, natural gas and coal.

Traditional (Historical use): This type provides a big amount of global energy. Ex: Hydraulic, coal, uranium and oil.

Alternative (Historical use): This type provides energy and it´s easier to obtain than traditional energy. Ex: Wind, solar, biomass and geothermal.

Primary (Transformation): This type is obtained from the environment whitout any kind of transformation. Ex: Gas, solar, coal and wind.

Secondary (Transformation): This source is obtained after the transformation of a primary source. Ex: Electricity, gas, petrol and oil.

5.1.2 Exercise 5 sol Forms and Sources

5º Exercise: Make a list of 20 objects indicating the source of energy used and the energy obtained .

For example: TV-Electricity

Object Energy Source Energy obtained

TV Electricity Light

Washing machine Electric energy Mechanical

Radiator Electric energy Calorific

Computer electric light

Fridge Electric energy Mechanical-Calorific

Toaster Electric energy Calorific

Bulb Electric energy light

Dishwasher Electric energy Mechanical

Transformer Electric energy Electrical

Furnace Chemical energy Calorific

Back

Object Energy source Energy obtained

Fridge Electricity Calorific

Computer Electricity Light

Lamp Electricity Light

Microwave Electricity Light- Calorific

Toaster Electricity Calorific

Vitro Electricity Calorific

Deep fryer Electricity Calorific

Loudspeaker Electricity Sound

Freezer compartment Electricity Calorfic

Thermal printer Electricity Calorific

Games console Electricity Light

Coffee maker Water and Electricity Calorific

Calculator Electricity Light

Mobile phone Electricity Light

Telephone Electricity Sound

Car Electricity Mechanical

Alarm clock Electricity Sound

Dishwasher Electricity Calorific and Mechanical

Washing machine Electricity Calorific and Mechanical

Alarm Electricity Sound

5.2.1 Exercise Sol. Electric energy. Production1º Exercise:

Compare the use of electricity at home with the use of coal, oil, gas, solar, wind, geothermal, uranium.

Coal produces a lot of smoke and dust if we use it to heat or cook. Also requires a lot of space to store it.

Oil is used to heat houses but is really dangerous if we use it to cook or to create light.

Solar energy can be used to heat water, but it doesn’t get really hot. We can use it to cook but it is too slow.

Gas is used to cook but it’s quite dangerous and is more difficult to clean. We use it to heat water and houses.

Wind, geothermal and uranium can’t be used directly at home, so we need to get electricity from them.

5.2.1 Exercise Sol. Electric energy. Production2º Exercise:What do we mean when we say that the electricity is clean?Electricity is usually defined as clean energy because we can use it

at home anytime anyplace. It doesn’t create any dust, gas or smell as does coal, gas or oil.

But we have to remember that to create electricity we are different energy sources like coal, oil, nuclear, etc that have several disadvantages like pollution, nuclear waste, environment destruction, etc.

Back

Nuclear power station5.2.2 Nuclear Power Stations

Steam

Mine Reactor

Boiler

Turbine

Generator

Transformer

Cooling

Mechanical Energy

Ele

ctric

ity

Cold Water

Heat

Pylons

Hig

h V

olt

Ste

am

Uranium

Nuclear

The water from the river is stored in a dam. The water is released has high energy thanks to the height, so it moves the turbine. The mechanical energy obtained is transformed into electricity inside the generator. This electricity is transformed into high voltage electricity in a transformer. This electricity is connected to the pylons and transmitted to the electric grid

5.2.2 Hydro Power Stations

River Dam

TurbineGenerator

Transformer

Mechanical Energy Electricity

Water high pressure

Pylons

Hig

h V

olt

Water

River

Water

Back

Solar Tower power station5.2.2 Solar Tower Power Stations

Steam

Sun Heliostats

Boiler

Turbine

Generator

Transformer

Cooling

Mechanical Energy

Ele

ctric

ity

Cold Water

Light

Pylons

Hig

h V

olt

Ste

am

Light

Back

Photovoltaic power station5.2.2 Photovoltaic Power Stations

AlternateCurrent

Sun Solar panel photovoltaic

Inverter

Electric current

Light

Back

Transformer

Pylon

High Voltagecurrent

Wind power station5.2.2 Wind Power Stations

Wind Rotor

Gear Box Generator

Transformer

Multiplied Mechanical Energy

Ele

ctric

ity

Pylons

Hig

h V

olt

Mechanical energy

Mechanical energy

Back

Tide Power Station5.2.2 Tide Power Stations

Sea Dam

Turbine

Generator

Transformer

Mechanical Energy Electricity

Water high pressure

Pylons

Hig

h V

olt

Tide Waterraise

Water

Back

Biomass power station5.2.2 Biomass Power Stations

Steam

Biomass

Furnace

Boiler

Turbine

Generator

Transformer

Cooling

Mechanical Energy

Ele

ctric

ity

Cold Water

Heat

Pylons

Hig

h V

olt

Ste

am

Bio fuel

Back

Geothermal power station5.2.2 Geothermal Power Stations

Steam

Water

pump

Lava

Turbine

Generator

Transformer

Cooling

Mechanical Energy

Ele

ctric

ity

Cold Water

Pylons

Hig

h V

olt

Ste

am

Water

Back

Exercise 8Calculate the % of energy wasted in calorific energy when

we transport 1250 kw with a cable that has 10 Ohm if:Voltage is 250kVVoltage is 25 KV


€

Pabsolute = VI ; Pcalorific = I2R ; V = IR

Ploss% =Pabsolute − Pcalorific

Pabsolute

x100

Exercise 8Calculate the % of energy wasted in calorific energy when we

transport 1250 MW with a cable that has 10 Ohm if: Voltage is 250kW


98,991001250000

2501250000%P

100P

PP%P

25001)5(RI P

5A250000

1250000

V

PI ; VI P

Transfered

absolute

calorificabsoluteTransfered

22calorific

absoluteabsolute

x

x

W

%02,098,99100%Plost

Exercise 8Calculate the % of energy wasted in calorific energy when we

transport 1250 MW with a cable that has 10 Ohm if: Voltage is 25 KV


981001250000

250001250000%P

100P

PP%P

2500001)50(RI P

50A25000

1250000

V

PI ; VI P

loss

absolute

calorificabsoluteloss

22calorific

absoluteabsolute

x

x

W

%298100%Plost

Energy Unit if 3 ESO Technology

Education

Transcript of Energy Unit if 3 ESO Technology