UNIT 4: ENERGY AND ITS TRANSFORMATION
KEY WORDS
1. – ENERGY SOURCES The energy we consume has many different uses: § Household uses: operating household appliances, heating systems, means of transport, etc. § Industrial uses: the operation of factories and businesses, construction, agriculture, etc.
Industrial park: a designated area for the location and development of industry. Electricity substation: facility where electric transformers are located to distribute power.
Energy sources are natural resources from which different forms of energy are obtained We can classify energy sources in several ways: § By availability in nature: renewable or non-renewable. § By origin: primary or secondary. § By use: conventional or non-conventional. § By environmental impact: clean or polluting.
1. 1- ELECTRICITY Electricity is the most widely used form of energy in industrialized societies for two reasons: § Its capacity to be easily transformed into other forms of energy. § The possibility of transporting it long distances at a low cost. Electric power plants Electrical power plants use an external source of energy to produce electricity. To do this, they rely on a turbine-alternator system.
§ §
The turbine converts mechanical energy into the rotating movement of a shaft. The alternator is connected to the turbine shaft. As the shaft moves, it produces alternating electrical current.
~ 2 ~
UNIT 4: ENERGY AND ITS TRANSFORMATION
Once electricity is generated, it must be transported to towns, cities or industrial parks.
The transportation of electrical energy involves several processes: raising the voltage to 220000V or 400000 V, transporting it by high voltage cables connected to towers, decreasing the voltage al electricity substations until it reaches 3-30 kV and distributing it to the consumption centers.
1. 2- ACTIVITIES 1.
Copy the following chart in you exercise book and complete it by ticking the corresponding boxes.
~ Â 3 Â ~
UNIT 4: ENERGY AND ITS TRANSFORMATION
2. Listen to the four descriptions of different types of energy sources and decide which description relates to which source. CONVENTIONAL
RENEWABLE
SECONDARY
CLEAN
3. In your exercise book, list the essential properties that the conductors that are used to transport electricity must have. 4. Sometimes, as you can see in the photograph below, high voltage cables pass through populated areas. Can you think of any possible problems or risks?
~ 4 ~
UNIT 4: ENERGY AND ITS TRANSFORMATION
KEY WORDS
2. – ELECTRIC POWER PLANTS
Compressor: machine that augments or increases the pressure of the gas. Blades: the curve, moving parts of a turbine.
2.1 – CONVENTIONAL POWER PLANTS § §
§ §
In thermal power plants, water is heated in a boiler by the heat generated from the combustion of a fossil fuel (natural, gas, coal or petroleum). The steam that is generated moves the turbine connect to the generator.
Combined cycle power plants obtain electricity as the result of two combined cycles: a cycle the uses air and gas, and conventional thermal cycle. During the first cycle, a gas turbine is used that includes a compressor. The combustion gasses from the firs cycle are transported to another boiler, where they transfer their energy.
Nuclear power plants use a nuclear fission reactor the produces heat to generate the pressurized steam needed to move the turbine rotor. Hydroelectric power plants use the potential energy provided by height of the water stored in a dam, converting it into kinetic energy. This energy moves the blades of the turbine. There are two types: gravity and pump.
~ 5 ~
UNIT 4: ENERGY AND ITS TRANSFORMATION
2.2 – NON - CONVENTIONAL POWER PLANTS The environmental problems caused by conventional power plants have led to the creation and development of non-conventional or alternative energy power plants. § §
§ §
Wind farms use kinetic energy of the wind to move the blades of rotor at the top of a tower; this is referred to as a wind turbine. Solar power plants use the Sun’s energy. There are two types: photo-thermal power plants are thermal power plants in which steam is produced by solar radiation, while photovoltaic power plants transform solar radiation directly into electricity, using panels of photovoltaic cells.
Biomass consists of all organic compounds that era produced through natural processes. Biomass thermal power plants are thermal power plans that use biomass as fuel. Geothermal power plants use the heat found at deep layers in the Earth.
KEY WORDS Photovoltaic: relating to production of electric current by exposure to light. Thermal gradient: difference in temperature between the surface and the deepest levels of the ocean.
~ 6 ~
UNIT 4: ENERGY AND ITS TRANSFORMATION
2. 3- ACTIVITIES 1.
Listen to the description of a power plant. Which type is being described? Check your ideas with your partner, and then read the descriptions again to see if you were right.
2. Use a map of the autonomous community where you live to find the thermal power plants the use both combustion and nuclear energy. Then make a table in your exercise book to explain the advantages and disadvantages of each type of power plant. 3. Use the Internet to find information about hydroelectric power plants close to where you live, then copy and complete the table below.
4. Use the Internet to find out the location of wind farms and solar power plants in the autonomous community where you live, then complete the table below.
5. Find put information about geothermal energy and answer the following questions: a.
What would be the geographical and climatic characteristics for an area to locate a wind farm? b. Which countries of Europe use thus type of energy? c. Which regions of Spain would be most suitable?
~ Â 7 Â ~
UNIT 4: ENERGY AND ITS TRANSFORMATION
3. – ENVIRONMENTAL IMPACT As part of a technology project, it´s mandatory to carry out an environmental impact assessment to find out what changes it would provoke in the environment.
3.1. - ENVIRONMENTAL REPERCUSSIONS Energy consumption is preceded by a long process consisting of several stages, each of which has an environmental cost, precedes energy consumption. § The exploitation of fossil fuels and nuclear energy leads to the depletion of resources. Furthermore, fuel extraction processes are sometimes harmful to the environment. In particular, timber extraction has meant the disappearance of large forested areas. § Petroleum is transported by means of oil pipelines and oil tankers. Both can have an accident, which means the risk of a spill. Some spills at sea have caused oil slicks that have taken years to disappear. § Large hydroelectric power plants change the natural cycle of rivers, flood large areas and deteriorate the ecosystem, in addition to the risk of accidents. § Conventional thermal power plants produce air pollution, gives off large amounts of CO2, which increases the greenhouse effect, and emit gasses that cause acid rain. § Nuclear thermal power plants are accompanied by the risk of a nuclear accident and the problem of nuclear waste. § The fuel we use in motor vehicles and heating system gives off gases and pollutants. Some solutions: § Energy efficiency policies attempt to increase the efficiency of the everyday appliances and devices we use. § It is essential to reduce the consumption of all forms of energy. § We must adopt habits that are more respectful of the environmental, such as using public transport or bicycles. § The use of renewable energy sources is fundamental.
~ 8 ~
KEY WORDS Depletion: reduction or exhaustion of resources due to overuse. Timber: wood processed from tress harvested from forests. Oil slick: a film of crude oil leaked from ships, which floats on top of sea water. Grennhouse effect: heating up of the Earth caused by trapping part of the Sun´s radiation by the Earth´s atmosphere.
UNIT 4: ENERGY AND ITS TRANSFORMATION
3. 2- ACTIVITIES 1.
What are the ‘greenhouse effect’ and ‘acid rain’? What do these phenomena have to do with energy use?
2. How do we pronounce the following words? Practise saying them and mark the stress. Then listen and check. Depletion
Timber
Ocean trench
Oil slick
3. In your exercice book, make a list of things that you and your family do to save energy. What other things could you do? Compare your list with a partner. 4. Choose the correct words in italic in the following sentences. a. Explotation of fossil fuels leads to the depletion / renewal of resources. b. Oil is transported by / stored in oil tankers. c. Nuclear waste can be dangerous for hundreds / thousands of years.
~ 9 ~