NATURAL SCIENCE IN ENGLISH

2nd ESO

OBTAINING AND USING ENERGY

Surnames:

Name:

Group:

UNIT OBJECTIVES

• Learn about different forms of energy

• Understand the relationship between energy, work and machines

• Compare renewable and non-renewable sources of energy

• Explain energy consumption and how to save energy

INTRODUCTION

Energy drives the Universe and is part of all the changes which take place on Earth.

The Sun is our main source of energy. Without it, there would be no life and most

other sources of energy would not exist.

Modern societies are totally dependent on electricity and hydrocarbon-based fuels.

The disadvantage of depending on energy is that most sources of energy cause

pollution and are running out.

We have to use clean, renewable sources of energy and use less energy.

TALK ABOUT IT

• Is the Sun a source of energy? And a bonfire?

• List five sources of energy. Which of them could run out?

• Will we always have oil to use?

• Name a source of energy which will not run out and does not cause pollution.

• Is the use of energy increasing? Why?

1. FORMS OF ENERGY

1.1. ENERGY

Energy is a property of matter which gives it the ability to produce change in its

own physical and chemical properties and in those of other bodies.

1 cal = 4,18 J

1.2.THE MAIN FORMS OF ENERGY

The main forms of energy are:

• Thermal energy: energy which is transferred from a hot body to a colder one.

• Kinetic energy: energy possessed by a body which has acquired velocity. The

greater the velocity, the greater the kinetic energy.

The petrol burnt in a combustion engine

makes it move and gives it kinetic

energy

Ec = ½ · m · v₂

• Potential energy: energy possessed by a body by virtue of the position it

occupies.

Ep = m · g · h

g = 9,8 m / s₂

It can be:

- Gravitational potential energy: energy possessed by a body which is at a

certain height above the ground. The higher the body is above the

ground, the greater the energy.

This snowboarder accumulates a lot

of potential energy at the high point

of his jump

- Elastic potential energy: energy possessed, for example, by a spring or a

drawn bow.

The potential energy accumulated in

the elastic bow shoots the arrow

when the string is released

• Electrical energy: energy produced by the movement of electrons in a conductor.

• Chemical energy: energy stored in chemical compounds which can be seen in chemical

reactions.

KEY WORDS

Chemical energy Conservation

Energy Electrical energy

Combustion Kinetic energy

Potential energy Thermal energy

1.3.ENERGY CONVERSION

Energy can be converted from one type into another:

• The chemical energy from the combustion of petrol in an engine is converted

into a car’s kinetic energy.

• Electrical energy is converted into thermal energy (an electric heater), kinetic

energy (an electric motor) or light (a light bulb).

• In a hydroelectric power station, the potential energy of the water behind the

dam, which is at a higher level than the turbine of the generator, is converted

into kinetic energy which drives

the turbine.

The energy of the cyclist’s muscles has to

overcome the force of friction and air

resistance

1.4.ENERGY CONSERVATION

Energy is continually converted from one type to another, but is never lost: the

total amount of energy always remains the same. This is why we say that energy is

conserved.

Energy is not created or destroyed, it is just transformed!

1. Listen to the definitions. Which type of energy is being described?

2. Reorder the words to make questions:

a. Burn/substances/what/thermal/produce/when/energy/they?

b. Type/energy/stored/of/in/a/is/battery/what?

c. Heat/what/of/is/iron/used/to/kind/an/energy?

d. Converted/how/a/engine/energy/car/is/into?

3. Answer the questions from activity 2.

4. Complete the sentences to explain how energy is converted:

The electrical energy in A radiator

A drill

A lift

A light bulb

Is converted into…

2. THE NEED FOR ENERGY. SOURCES OF ENERGY

2.1. THE NEED FOR ENERGY THROUGH HISTORY

In prehistoric times, human beings, who were nomadic hunter-gatherers,

needed no other energy than fire to keep them warm and cook their food.

Centuries later, apart from fire, humans also used the power of wind, water and

animals to obtain food and for transport.

Figure 1. A historical source of energy: the energy of

the water in a river moves the waterwheel of a flour

mill or oil mill

The steam engine, which worked by burning coal, marked the start of the great

industrial advances which brought about a radical change in the way people lived.

Figure 2. Watt’s steam engine, used to power textile machinery and

manufacture cloth, was invented in 1765 by the British engineer, James Watt

Today, the use of vehicles and new technologies requires vast amounts of

energy, especially electricity and fuel.

2.2. SOURCES OF ENERGY

Sources of energy is the name given to the energy resources which humans use

to generate energy. This energy may be used directly, or converted into other types of

energy.

For example, the Sun is the Earth’s most important source of energy. It provides

the heat necessary for life to develop, it helps plants to grow and plays a part in many

atmospheric phenomena, such as the generation of wind.

Figure 3

KEY WORDS

Consumption Renewable

Energy resource Run out

Last Source of energy

Non-renewable Use up

2.3. RENEWABLE AND NON-RENEWABLE SOURCES OF ENERGY

Depending on their capacity for regeneration, sources of energy are classified in

two groups:

• Non-renewable sources of energy: these are the sources which, once they are

used up, cannot be replaced.

• Renewable sources of energy: these are the sources which are constantly

renewed or are practically inexhaustible. The most important of these are solar

energy, wind energy and hydraulic (water) power.

Figure 4.The Sun is our main source of

energy

NON-RENEWABLE SOURCES OF ENERGY ARE RUNNING OUT!

All over the world, energy consumption increases every year. For this reason, it is very probable that non-renewable energy resources will be exhausted in a relatively short time (as can be seen in the graph below). Faced with this situation, we need to take the following steps:

- We need to reduce energy consumption - We need to use renewable sources of energy more

QUESTIONS:

1. Which energy resource do people think will be the first to run out? And the last?

2. How long will coal reserves last at the current rate of consumption? 3. Which countries control most of the reserves?

1. Look at figures 1-4. Listen and write true or false.

2. Complete the sentences using use up, last, run out:

“Coal reserves will ………………………… 122 years. Oil will ………………….. in 42 years.

We will ……………….. gas reserves in 60.4 years”.

3. What is the difference between renewable and non-renewable sources of

energy? Make a table showing four types of each. Compare with a classmate.

4. Explain how plants use the energy that they receive from the Sun.

5. What do you think will be our main source of energy in 100 years’ time? Discuss.

3. NON-RENEWABLE SOURCES OF ENERGY

3.1. COAL

Coal is a solid, black rock. It is the fossilized remains of huge masses of

vegetation buried under the ground millions of years ago.

It is used mainly as fuel in coal-fired power stations, where it heats the water

that produces the steam to drive the turbines that produce electricity.

3.2. OIL

Oil is a dark-coloured, viscous liquid produced by the decomposition of marine

microorganisms millions of years ago which sank to the seabed when they died,

where they were covered by layers of sand and mud.

Oil is usually found in large pockets deep under the ground. It is obtained by

drilling wells on land or by means of oil rigs out at sea. From oil, we obtain

extremely useful products such as petrol, diesel and fuel oil.

3.3. NATURAL GAS

Natural gas is formed in a similar way to oil. It is a mixture of gases containing

large amounts of propane and butane.

Natural gas is used in power stations, which produce electricity, and in homes

(for heating and cooking).

3.4. URANIUM

Uranium is a radioactive metal from which we can obtain huge amounts of

energy because of the reactions in the nuclei of the atoms. This energy is used

to generate electricity.

The radioactivity of uranium and its waste products make it necessary to take

special safety precautions.

1. Listen and write the key word being described:

2. Complete the table:

Source of energy Extraction products

opencast

oil

propane

KEY WORDS

Coal Oil rig

Oil Turbine

Power station Well

4. DISADVANTAGES OF NON-RENEWABLE ENERGIES

4.1. POLLUTION OF THE ENVIRONMENT

The production, transport and use of non-renewable sources of energy

generates environmental pollution.

Power stations, factories, vehicles and heating systems all emit harmful

substances into the atmosphere which cause air pollution.

The substances generated by many

processes pollute the air.

4.2. POLLUTING SUBSTANCES

Pollutants are divided into two types: primary pollutants and secondary

pollutants.

• Primary pollutants are substances produced by processes of combustion, such

as carbon oxides, sulphur oxides and particles of metals.

• Secondary pollutants are generated by interaction between primary pollutants

and other substances.

For example, nitric, carbonic and sulphuric acids are formed when primary

pollutants react with water vapour in the atmosphere and fall to the ground as

acid rain.

KEY WORDS

Harmful Decay

Pollutant Greenhouse effect

Drought Oil slick

Flooding Acid rain

CAUSE EXAMPLE

ACTIVITY: Listen. What four causes of air pollution does the speaker mention? What

examples are given?

THE RISKS OF NUCLEAR ENERGY

On 11th March 2011, off the north-east coast of Japan, there was an earthquake

measuring 9.0 on the Ritcher scale.

As a result of the earthquake, there was a tsunami which flooded the coast and

damaged the three nuclear reactors of the Fukushima nuclear power plant

which were functioning at the time.

Both the damage caused to the reactors, and the measures taken to cool them

down caused radioactive substances to be released into the atmosphere.

One of the reactor buildings at Fukushima nuclear power plant after the

accident

ACTIVITY

Look on the Internet for information on the Fukushima nuclear accident. Why

did it happen? What negative consequences did it have?

THE ENVIRONMENTAL COSTS OF ENERGY PRODUCTION

Pollution of the environment due to the way we obtain and use energy produces

adverse effects like the following:

• Acid rain: contaminating, harmful gas emissions form acids in the atmosphere

and fall to the earth when it rains or snows as acid rain. This has negative

effects on both terrestrial and aquatic life. It even affects buildings, which are

damaged by what is known as building decay.

• Intensification of the natural greenhouse effect: the burning of fossil fuels

releases carbon dioxide (CO₂) into the atmosphere. This gas produces an

intensification of the natural greenhouse effect.

As a result, the Earth cools down less than usual and its temperature rises. This

global warming causes climate change. Among the most important of these

changes are the melting of glaciers and the polar icecaps, and an increase in the

number and scale of natural disasters related to weather conditions (flooding,

prolonged drought).

• Health problems: air pollution produces respiratory and pulmonary problems

(asthma, bronchitis), heart problems, irritation of the eyes, digestive disorders

and allergies. Children and old people are especially vulnerable.

• Pollution of the seas and oceans: oil is transported by sea in oil tankers, which

sometimes have accidents. The oil they are carrying may be spilt into the sea,

with the resulting oil slicks polluting both the sea and the coast.

• Radioactive substances: because it is highly contaminating and dangerous,

nuclear waste must be stored under strict safety conditions.

• Oil slicks: they endanger the lives of marine animals and plants as well as those

that feed on them.

5. RENEWABLE SOURCES OF ENERGY

5.1. WATER POWER

Hydroelectric power stations obtain electrical energy from water power.

Water is a resource which does not run out: the water cycle constantly renews

the water on our planet.

Figure 1

5.2. SOLAR ENERGY

Solar energy is the energy which comes directly from the Sun. this energy is

practically inexhaustible.

We use the energy of the Sun:

• As a source of heat. We use solar panels, which are made of large sheets of

glass with tubes containing water under them.

The Sun’s rays penetrate the glass and heat the water, which can also be used

for heating.

Figure 2. Solar panels on the roof of a house

• In the production of electricity. Photovoltaic panels are used to convert sunlight

directly into electricity.

5.3. WIND ENERGY

The force of the wind (wind energy) is harnessed using wind turbines. The wind

makes the blades of a turbine spin around. This powers a generator which

produces electricity.

Figure 3

Figure 4. photovoltaic power plant

5.4. BIOMASS ENERGY

Biomass energy is obtained from waste plant matter from forests or crops,

waste products from the water-treatment process, waste cooking oils and even

from crops specifically for this purpose, called energy crops.

The biomass is burnt to generate heat or electricity or is turned into fuel for

vehicles (biodiesel and bioalcohol).

Figure 5

5.5. GEOTHERMAL ENERGY

Geothermal energy comes from the heat inside the Earth; it can be used to

produce electricity or to provide heating.

To produce electricity, cold water is pumped at pressure into a very hot zone in

the Earth’s interior, where it turns to high-temperature steam.

The steam escapes to the surface through a special pipe where it is used to

drive a turbine connected to an electricity generator.

A geothermal power plant. Because of their very specific nature, they can only be used

in certain parts of the world.

KEY WORDS

Biomass Geothermal

Blade Harness

Dam Hydroelectric

Crop Panel

1. Look at figures 1-5. Listen and write which type of energy is being described.

2. Define the following words: panel, crop, blade, dam, harness.

3. Look at figure 1. Describe how a hydroelectric power station works: “A dam is

built to create….Water is released and this moving water turns…”

4. Give two different uses of solar energy.

5. Describe how geothermal energy works: “geothermal energy comes from….Cold

water….This produces…., which escapes through….On the surface,…”.

THINK ABOUT IT:

6. Where does biomass energy come from?

7. What are the advantages of renewable sources of energy?

8. Can you think of any disadvantages of renewable energy resources?

9. Make a table to compare different renewable energies.

Type Needs Uses

Water Dam, turbine….

Solar

Wind electricity

Biomass

Geothermal

6. ENERGY CONSUMPTION

6.1. SUSTAINABLE ENERGY CONSUMPTION

Three quarters of all the energy produced is consumed by on 15% of the Earth’s

population. Therefore, it is vital:

• To share out energy resources among all the Earth’s population in a fair and

balanced manner.

• Not to think only of our well-being today and be blind to what will happen

tomorrow.

KEY WORDS

Balanced Share out

Breakdown Sustainable

Household Well-being

ACTIVITY Listen to the definitions and match them to the key words

WAYS TO SAVE ENERGY

Measures for saving energy are the responsibility of both

individuals and society in general. Some of the ways to save

energy are:

• To save energy we must avoid:

- Using air-conditioning and heating irresponsibly or

using too much hot water when we wash.

- Using the remote control to leave televisions or radios

on standby because, although they seem to be turned

off, they are not. They are still using electricity.

- Using electrical appliances incorrectly and leaving

lights on when there is no one in the room.

• To save energy we must encourage:

- The use of thermal insulation in buildings and the use

of solar power, both for heating and electricity

generation.

- The use of public transport. For this we need good

public transport systems.

- The habit of walking or cycling instead of using

vehicles which run on petrol or diesel.

1. Look at the pictures and compare them:

2) Raise your hands: - Who would prefer to live at the age of a? - Who would prefer to live at the age of b?

3) Work in pairs and discuss it. 4) Now think from the point of view of energy (fastest hands first): - Which types of energy are used in the first picture? - Which types of energy are used in the second one? - Where do those come from? - How can we save energy at home?

KEY WORDS:

Consumption Energy resource Non-renewable

Renewable Source of energy Coal

Oil Power station Natural gas

Polluting substances Drought Flooding

Green house effect Oil slick Acid rain

Water power hydroelectric Solar energy

Biomass energy Geothermal energy

GLOSSARY

acid rain (n): rain which is acidic due to the presence of pollutants.

balanced (adj): distributed evenly.

biomass (n): organic matter used as a source of energy.

blade (n): the arm which makes a wind turbine go round.

breakdown (n): a list of the components of something.

chemical energy (n): energy stored in chemical compounds which can be seen in

chemical reactions.

coal (n): a black mineral which is burnt to generate heat.

combustion (n): the process of burning.

compound machine (n): a machine which is made up of two or more simple

machines.

consumption (n): the act of using something up.

crop (n): a plant which is grown on a large scale.

dam (n): a wall built across a river to create an artificial lake or reservoir.

decay (n): the gradual destruction of something.

displace (v): to move something to a different place.

dissipated energy (n): the part of the total energy consumed by a machine which is

lost and is not useful energy.

drought (n): a long period when there is no rain.

effort (n): a force which does not produce displacement and does not do work.

electrical energy (n): energy produced by the movement of electrons in a conductor.

energy (n): a property of matter which gives it the ability to produce change in its

own physical and chemical properties and in those of other bodies.

energy conservation (n): the principle that the total amount of energy in a system

remains constant.

energy resource (n): a source of energy.

flooding (n): when a place that is normally dry becomes covered with water, due to

heavy rain, etc.

geothermal (adj): which comes from heat inside the Earth.

greenhouse effect (n): when gases in the atmosphere retain part of the heat from

the Sun and stop it escaping back into space.

harmful (adj): which causes damage, injury or problems.

harness (v): to control something to use its power.

household (n): all the people living in one house.

hydroelectric (adj): which uses the power of water to generate electricity.

joule (n): the SI unit of work.

kinetic energy (n): the energy possessed by a body which has acquired velocity.

last (v): to continue to exist or remain usable.

non-renewable (adj): which cannot be replaced once it has been consumed.

oil (n): a dark liquid extracted from under the ground; it can be distilled to produce

fuels such as petrol.

oil rig (n): a large structure used for making wells to extract oil from under the

ground.

oil slick (n): a layer of oil on the surface of the sea.

panel (n): a thin, rectangular piece of equipment.

pollutant (n): a substance which causes pollution.

potential energy (n): the energy possessed by a body by virtue of the position it

occupies.

power station (n): a factory where electricity is generated.

renewable (adj): which can be replaced.

run out (v): to be completely used up.

share out (v): to divide something up and distribute it among different people.

simple machine (n): a machine which does its work in a single step.

source of energy (n): something we get energy from.

sustainable (adj): which can be maintained for a long time without causing damage

to the environment.

thermal energy (n): energy in the form of heat.

turbine (n): a machine for generating power in which kinetic energy is converted into

mechanical energy.

use up (v): to consume something until it disappears.

useful energy (n): the part of the total energy consumed by a machine which does

work.

well (n): a hole drilled into the ground to extract oil, etc.

well-being (n): the state of feeling comfortable, healthy and happy.

work (n): the transfer of energy caused by a force which displaces a body.