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Earth’s Resources

Our world is becoming ever more crowded, and filled with machines and gadgets. Making these things requires vast amounts of energy to drive machines, to provide heat and light, and to power all forms of transport. Some of the raw materials needed for manufacturing and energy are grown. Threes provide wood for fuel, furniture, building, paper and so on. Plants and animals provide materials such as wool, cotton and leather. But today most of the raw materials and fuels we use come from the ground.

Minerals

Vital metals such as iron, copper, tin, silver and gold are all minerals. They come from the rocks of the Earth’s crust. Sometimes they are found near the surface, but often deep mines must be dug to reach them. The metals are always mixed with unwanted materials in a substance called ore. The ore has to be treated to extract the pure metal. Many minerals other than metals are also mined, quarried or dug out of the rocks themselves, for buildings; sand, for concrete and for making glass; fertilizers; and even the talc in talcum powder.

Fuels

Most fuel for energy and power also comes from deep underground, in the form of oil, gas and coal. These ‘fossil’ fuels were created millions of years ago from the remains of plants and animals. These remains became deeply buried, and the great preassure far underground helped turn forest trees into coal, and the remains of countless tiny plants and animals into oil and gas.

Coal

Some coal is near surface and can be reached by open cast mining. The soil and other surface layers are simply dug away to reveal the coal, but usually it is mined from deep below the ground. However, extracting coal remains an expensive task, and for some time the world has been using more oil and gas and less coal. These fuels are easier and cheaper to obtain and to transport, and they give out more heat.

Finding Oil and Gas

The first step is to find a likely spot. Geologists study the structure of the rocks using scientific instruments such as seismographs (earthquake detectors). They fire explosive charges in holes in the ground, and measure the tiny quakes or shock waves that bounce back off the various layers of rock below. When a promising spot is located, the next step is to drill a hole or well. This may have to go hundreds or even thousands of metres down into the rock. When the oil or gas is reached, it is usually under such great preassure that it shoots up to the surface by itself. But sometimes it must be pumped up. In either case, once it is flowing it is controlled by taps and valves, and transported along pipelines. The raw or crude oil must be treated at a refinery before it can be used. There it is purified, and broken down into many different fuels and other materials, ready for transport around the world by pipelines, road vehicles and giant oil tankers. Coal and oil are burnt as fuels, but they also provide the raw materials for all sorts of other materials including many plastics and ‘man made materials’ for clothing. All three fossil fuels – coal, oil and gas – may be used directly as fuels, or they can be burned to generate electricity. All these minerals and fossil fuels form part of the Earth’s resources, and they are all limited. There is a certain amount of them in the world, and no more. Eventually they will run out. We must conserve what we have, and we must look for new fuels and new sources or raw materials. One of the first steps has been to start harvesting the resources of the seas and oceans. Over a third of the world’s oil is now produced from oil rigs – giant structures out at sea from which oil wells are drilled in the sea bed. Already some minerals, like salt and magnesium, are extracted form the sea. But at the moment, the most serious problem is fuel. Some experts belive that we may run out of oil and gas in 50 or a hundred years, and we may run out of coal a couple of hundred years later.

Hydro-electricity

This is produced by fast flowing rivers and waterfalls. The water spins turbines which generate electricity. Hydro-electric power is especially valuable in mountainous countries like Norway, Switzerland and Scotland, and in countries with little coal.

Nuclear Energy

Nuclear or atomic power is another way of generating electricity without using up fossil fuels. It produces an enormous amount of energy from a minute amount of the mineral uranium. One kilogramme of uranium burnt in a nuclear reactor generates as much energy as 4 ½ million kilogramme of coal.

Geothermal Energy

Some other possible sources of energy for the future are described on page 208. There is one other natural resource. Geothermal energy (see illustration) taps the same underground heat that sets volcanoes erupting and geysers and hot springs bubbling. In some areas of the world water lies deep underground above hot volcanic rock. Engineers can drill down to this water and use its steam to drive turbines for generating electric power. Where a hot spring bubbles up to the surface, its water can simply be piped around homes, offices, and factories to provide natural central heating. Scientists are also studying the possibility of using this underground heat in regions where there is no water trapped above the hot rock. They hope to drill deep holes down into the hot rock. Water flowing down one hole would turn to steam and rise up another hole. Geothermal energy, hydro-electric power and other forms of natural energy from the Sun, the wind and the sea, will last as long as our planet. Building the necessary structures and equipment costs a lot, but the energy is clean and safe, and it wastes none of our planet’s valuable and diminishing resources. Source: Explorer Encyclopedia

Feautures Associated Modern Industry Resources; World Energy Resources; Crude Oil, Natural Gas, Coal, Electricity