Answer the following questions with reference to the article which follows.

Choose from A to H the answers to the numbered questions.

Which source of power...

01. ... is volatile when warmed? ..........................

02. ... is the dominant source of energy in some countries? ..........................

03. ... could help clean up the English environment? ..........................

04. ... was thought to be in short supply? ..........................

05. ... is a direct cause of illness? ..........................

06. ... is easy to extract? ..........................

07. ... is the most economical? ..........................

08. ... produces enormous heat? ..........................

09/10. ... depends on high technology? .......................... ...........................

11. ... is a bad investment? ..........................

12. ... is abundant? ..........................

A. nuclear power

B. nuclear fusion

C. methane hydrate

D. fossil fuels

E. natural gas

F. solar energy

G. wave and tidal power

SOURCES OF POWER

Nuclear power has lost its popularity since 1986, and the Chernobyl catastrophe. More recently, privatisation of the British electrical industry has demonstrated that nuclear power is hopelessly uncommercial, at least in Britain. No one wanted to buy shares in the nuclear power stations, so the government had to keep them. The taxpayer can now look forward to the high cost of decommissioning them. Lastly, the nuclear industry has begun to pay out large sums of money to some of the people claiming compensation for radiation-related diseases and deaths. Thus, for a number of reasons - danger, money, health - nuclear power looks bad, but yet some countries are dependent upon it. Sixty-five per cent of French electricity is produced by nuclear power. In Germany, 30%, and in Britain and Spain, about 20%. Because of that dependence, a great deal of vastly expensive research is being conducted into nuclear fusion. Possibly that may be where the future lies, but it is a long way off because of the complex technology required to create the magnetic fields needed to contain the fusion, which occurs at temperatures of 100 million degrees Centigrade.

Fossil fuels have also had a bad press because of their pre-eminent contribution to the greenhouse effect. Their advantage lies in their versatility and their availability. With fossil fuels things go wrong slowly, unlike a nuclear catastrophe where it all happens at once. As to their availability, until a few years ago, scientists thought the world would run out of natural gas within 50 years. Now it seems that there may be enough of the stuff to last for as long as 5,000 years. It exists in the form of solid methane hydrate, a chemically bound mixture of methane gas and water that occurs as vast sheets or lenses. It looks like water ice, and is quite stable as long as it is kept very cold. When it warms it quickly decomposes to give methane gas and water. The amount of gas inside the solid is considerable: a cubic metre of hydrate yields about 1.5 thousand cubic metres of natural gas.

Geologists have found the hydrate at more than 80 sites in the Canadian and Siberian Arctic. The deposits are vast: one exploration drilled nine successive holes off the coast of Guatemala and found the same four-metre thick hydrate zone. Off California, another deposit covers several hundred square miles and is 300 metres thick at the centre. Hydrate will form anywhere where the temperature is low enough or the pressure high enough. Russian geologists estimate that at least 85 per cent of the deep ocean floor is suitable territory. Some American sources say that the total gas available could be as high as 500 billion million cubic feet, enough for 5,000 years. Surface sea water at 20 degrees centigrade would be warm enough to melt the hydrate if it was pumped down to the sea bed. Even in the Arctic, one would only have to burn seven per cent of the gas evolving to heat enough air to keep up a steady flow of gas. Development of the hydrate will become commercially viable when the other conventional gas deposits - easier to extract - have been exhausted. By then, of course, the results of burning fossil fuels may have become so obnoxious, that the stuff will simply be left where it is.

As the extraction of fossil fuels becomes increasingly expensive, so the development of alternative, renewable energy sources makes steady, although slow, progress. Principal among them are solar energy, and wave and tidal power. Solar energy cells are now approaching 29 per cent efficiency, which compares with the 31 per cent efficiency of a coal-fired power station. At Stanford University in California, engineers have achieved these high efficiencies by modifying the design of the solar cell. They have roughened the surface to trap light, which bounces about within the silicon, dislodging electrons and setting up electrical currents. The cell is built on a silicon chip which is 80 micrometres thick and is three by five millimetres in size. It is expected that the new chip will halve the cost of today's solar energy.

In 1985, near Bergen, in Norway, the world's first wave power station was opened. The energy of the waves was captured, converted into electricity and delivered as light and heat into the homes of people living miles from the sea. Tidal power has been in use to generate electricity for over 20 years: although it provides only 240 megawatts of electricity, the station at Rance, in Brittany, has the distinction of producing the cheapest electricity in the world. When it first came into operation, it was considered a white elephant, but that was when oil cost less than a fistful of dollars.

Britain is ideally placed to take advantage of wave and tidal power. In theory, wave energy could provide the country with more electricity than is at present available from all existing power stations. It would also remove most of the acid rain that pollutes England and its neighbours. Development of such resources was not one of the success stories of the Thatcher years but, sooner or later, the investment, probably about £10 billion, will have to be made.

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©English Teaching Systems February 2005