3. Complete the table

Speaker	Position	The main ides of his/ her talk. The main advantages and disadvantages of the source mentioned in the speech
Speaker 1	Professor Marvin Burnham of the New England Institute of Technology	And nuclear power is the only real alternative for fossil fuels.
Speaker 2	A member of CANE, the Campaign Against Nuclear Energy, Jennifer Hughes.	He is against nuclear research because nuclear energy is dangerous (accidents, waste, terrorism).
Speaker 3	Dr. Woodstock the author of several books on alternative technology.	We should concentrate on more economic uses of electricity, because electricity can be produced from other sources of energy (sun, wind, tide, etc).
Speaker 4	Charles Wicks, MP, the Minister for Energy.	In the short-term, we must continue to rely on the fossil fuels. But our policy must be flexible.

4. Answer the questions.

7. Why do we need the alternative sources of energy? – Because the world’s energy resources are limited.

8. What are the alternative sources of energy? – Solar power, wind power, tidal power, wave power, hydroelectric energy.

9. What are the disadvantages of nuclear power? – It is dangerous (causes cancer), it produces radioactive wastes, there is a danger for nuclear power-stations of being captured by terrorists.

10. What advantages of nuclear power were mentioned in the discussion? – it is the only real alternative to fossil fuels. If we spent money on research now, we could develop stations which create their own fuel and burn their own waste.

11. What point of view do you agree with? Are you an optimist? – No answer is possible.

18. Understanding a lecture

Listen to the lecture, which has been divided into three sections, and then answer the questions below.

Section 1

Good afternoon. Today I'm going to continue with the next in my series of lectures on developing the Earth's resources. And I want this time to focus on sources of energy, and on the role of the engineer in developing the technology to make use of these natural sources of energy. And I'm going to start with geothermal energy, which could be an important resource in the future.

OK. What is geothermal energy? Well, it's the energy that is found in the Earth itself. Its use is based on the fact that there is a difference in the temperature of rock and water under the ground — under the Earth's surface — and the temperature at the surface. And this temperature difference allows the production of thermal energy which can either be used directly, or it can be converted into mechanical or electrical energy.

Normally, temperatures in the Earth increase as the depth increases. The exact temperature at any depth depends on the location but, to give an example, have a look at the graph in your books: Graph 1. The line on the graph represents the temperature gradient for a well drilled in the Sierra Nevada in the USA. At the Earth's surface — zero kilometers on the graph — you can see that the temperature is just about 15° Celsius. This temperature increases a little, to about 50°, at a depth of two and a quarter kilometers. By the time you get down to six kilometers, it's about 100°C, and at ten kilometers, it's about 130°C. That's the deepest that any wells have been drilled so far — but if we were to get down to the base of the Earth's crust, we would find temperatures up to 1000°C. At the centre of the Earth, the temperatures may be as much as 4,500°. So you can see that this is a source of energy that is well worth considering.

Section 2

Well, up to now, development of geothermal energy has focused on natural geothermal reservoirs. These are volumes of rock which have a high temperature — about 350°C. They're usually highly porous — that means the pores or spaces in the rock are filled with water. They also have a high permeability. That means that the fluid in the rock can be transmitted easily. So, in other words, it can also be extracted easily. We drill a well into the rock, and the thermal energy in the rock is transferred by conduction to the fluid, which flows to the well, and then to the Earth's surface. Now all this is very fine, but these natural reservoirs make up only a tiny fraction of the top ten kilometers of the Earth's crust. Most of the rock within the top ten kilometers won't give up its energy that easily. It is not sufficiently porous and does not have high permeability. What you would need to do is produce a network of tiny fractures artificially — probably using explosives — and then circulate water through the fractures. The water would gain heat from the rock, and could then be extracted by pumping, and would provide hot water at the surface. At the present time, this procedure is time-consuming and expensive and not therefore feasible.

So, although geothermal energy is present everywhere beneath the Earth's surface, it can only be used where certain conditions are met: First, where the energy is accessible to drilling — so not usually deeper than six to seven kilometers below the surface. Second, where the rock is of the right type to allow production of large quantities of thermal water. Third, where the conditions for drilling are favorable. And fourth, where there is a suitable location for a power-generating facility at the surface. Obviously, your costs will increase if the thermal water has to be transported over long distances by pipeline.

Section 3

Now, the use of geothermal electricity can be very important to a small country. Look at El Salvador, for example. Thirty two per cent of the total electricity generated in the country comes from the use of geothermal energy. And many other countries are developing this resource. If you look at the second graph in your books — Graph 2 — you can see that in 1980 the electrical generating capacity world-wide was about six thousand megawatts. According to some estimates, this will increase by nineteen per cent per year. So by the year two thousand, the capacity could be as much as a hundred thousand megawatts.

Surveys are being carried out all the time and new discoveries of workable geothermal resources are being made. In the USA alone, it is estimated that geothermal resources could produce enough energy to equal forty-seven years of oil consumption. So you can see that geothermal energy certainly has a role to play in the future. And this is particularly true if new technologies are developed for obtaining the energy in a more economically effective way — and for making use of that energy once we have accessed it.

KEY

1 Developing the earth's resources.

• Sources of energy (and the role of the engineer in developing technology to exploit these)

• Suggested answers:

Section 1: What is geothermal energy?

Section 2: Geothermal reservoirs (and how they can be exploited)

Section 3: Use of geothermal energy

2 Graph should look like the following:

3 porous: the pores (spaces) in the rocks are filled with water.

permeability: fluid in the rock can be easily transmitted.

• . . . transferring it to a fluid which is then brought to the Earth's surface.

• с

• reservoir not more than 7 km deep (must be accessible to drilling); rock is the right type; favorable conditions for drilling; suitable location for power-generating facility.

4 Graph should look like this:

5. No key is possible.

Check your understanding

KEY

1. . Most developed countries have been thoroughly explored for minerals; demand for minerals is increasing rapidly; the technology is available for exploiting the ocean as a source of minerals.

2. . The three methods are: (i) A shaft is sunk on land and the deposit is reached by building a tunnel, (ii) An artificial island is built above the deposit. A shaft is sunk through the island and is extended down to reach the deposit, (iii) Production platforms are built above the deposit. Drilling can be carried out from these platforms. The minerals are raised to the platforms and are treated 'in-place' (e.g. by leaching).

3. • (a): "The possibility of direct sea floor access ... the shaft collared on completion." (b) "Submarine orebodies . . . removed by dredging." (c) "Shattering by nuclear blast . . . leaching of the valuable mineral."

• a, b, d, f, h.

Exercise 19. Working in pairs, discuss one of the energy source, its advantages and disadvantages, its perspectives:

• fossil fuels. Main advantages: abundant and efficient. Disadvantages: cause environmental problems, they are running out (nonrenewable).

• nuclear power. Main advantages: produces large amount of energy, renewable. Disadvantages: environmental problems in case of accident, radioactive wastes, radioactive pollution.

• geothermal energy. Main advantages: renewable. Disadvantages: produces thermal pollution, emissions of gas;

• hydroelectric power. Main advantages: renewable, environmentally friendly (no greenhouse gases, radioactive waste, sulphur oxides). Disadvantages: displacing people and their farms and town, threatening habitats of fish and other wildlife, flooding areas.

Exercise 20. Organize a students’ conference “The modern problems of energy generation.

Make a report on one of the source of energy (4-5 min).

Consider some alternative sources of energy.

Discuss their perspectives for the future.

Preparation:

• Give to students a list of the possible topics for their reports, but encourage them to think of their own ones.

• Give the task to carry out research and prepare a written report.

• Help Ss to make a list of terms.

• Look through the papers prepared by the Ss in advance.

• Hand out the role cards according to Ss’ desires and abilities.

Student scientific conference

Do you know how to take part in a conference? If you don’t, here are some bits of advice. The only way of participating in an international congress is to do so whole-heartedly and intelligently. It is the behavior and active participation of the congress-goers which above all ensures the success of a congress. Don’t be the type of participant who cannot adapt himself.

Think about what you hope from the meeting. Remember that its duration is limited to a few days. Remember that the other participants expect you to contribute something. Be active, ready to listen to the ideas of others. Don’t be self-centred or quick-tempered. Familiarize yourself with the rules of the congress, but with a view of respecting them, not to causing difficulties.

Do not stay in an ivory tower, but do not take part in discussions just for the pleasure of hearing your own voice or of having your name written down in the minutes.

Make sure that by your own behavior you are helping the chairperson and other organizers in their difficult task of guiding the proceedings successfully to concrete conclusions, in an atmosphere of cooperation and friendship among the participants of each country. Contact with other participants.

If you wish do draw the greatest benefit from an international congress, make contact with persons who you already know but also make a point of meetings as large number of unfamiliar faces as possible.

Take advantage of meals, receptions and excursion, change to another group instead of staying with your countrymen, or at the same table, or in the same coach.

Discretion is all very well, but timidity is useless and annoying. Remember that others are in the same position as you, and many may be even more isolated. Introduce yourself to other people and make as many introductions as possible among other participants. Taking part is a discussion, be clear and brief. Don’t overstep your allotted time. This may annoy the chairperson and other participants. Make use of your notes but don’t simply read them out. A well-prepared impromptu speech will interest listeners far more than one read from notes.

Speak in the working congress language you know best and don’t try to display your multilingual talents. It should never be necessary for you to be translated into your mother tongue.

Don’t change your mind without good reason.

1) Make up your own communication on a scientific problem that you are interested in and speak in front of your fellow students bearing in mind the information you’ve got from the above text (see Appendix 3 for topics and information)