OBTAINING AND USING ENERGY

Transcription

1 NATURAL SCIENCE IN ENGLISH 2 nd ESO OBTAINING AND USING ENERGY Surnames: Name: Group:

2 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?

3 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. It can be: Ep = m g h g = 9,8 m / s₂ - 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.

4 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 Energy Combustion Potential energy Conservation Electrical energy Kinetic energy Thermal energy

5 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!

6 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 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

7 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.

8 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 Energy resource Last Non-renewable Renewable Run out Source of energy Use up

9 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

10 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?

11 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.

12 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 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.

13 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) 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.

14 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 Power station Oil rig Turbine Well

15 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 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 Pollutant Drought Flooding Decay Greenhouse effect Oil slick Acid rain

16 ACTIVITY: Listen. What four causes of air pollution does the speaker mention? What examples are given? CAUSE EXAMPLE

17 THE RISKS OF NUCLEAR ENERGY On 11 th 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?

18 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).

19 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.

20 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 SOLAR ENERGY Figure 1 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.

21 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).

22 Figure 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 Blade Dam Crop Geothermal Harness Hydroelectric Panel

23 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

24 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 Breakdown Household Share out Sustainable Well-being ACTIVITY Listen to the definitions and match them to the key words

25 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.

26 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

27 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.

28 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.

29 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.