4. The use the energy resources: non-renewable, alternative and nuclear.

4.1. Non-renewable energy. Renewable sources of energy means that the sources can be used forever to create the energy; non-renewable means that the source is limited and that one day it will come to an end. Non-renewable sources are fossil fuels that are buried under the ground: coal, oil and natural gas. The amount of energy in any fossil fuel depends on the amount of carbon that is contains. All fossil fuels produce carbon dioxide, the most important greenhouse gas, when they burn.

Today, coal provides 25% of world energy. Its reserves will last between 100 and 300 years if consumption does not change. Oil provides 50% of world energy. If world oil consumption continues at the same rate, and if we do not discover new reserves of oil, we will run out of oil in about 2020. Natural gas (methane) often occurs with deposits of oil. It has a very high carbon content. Methane and its combustion product, carbon dioxide, are both greenhouse gases and contribute to global warming. Natural gas provides about 20% of world energy today. World reserves of natural gas will probably last about 70 years.

Fossil fuels are running out. If we remain dependent on fossil fuels for most of our energy needs there will be a sudden crisis when the reserves are exhausted. We must try to develop alternative sources of energy before this crisis happens.

4.2. Alternative energy. Energy comes in many forms – heat, light, sound, electrical and mechanical. The problem is how to convert this energy into the type of energy we need most today – electricity. Wind power has been used for hundreds of years in the form of the old-fashioned windmill, which converted one form of mechanical energy (wind) into another (the milling process). The modern version of the windmill is the aerogenerator. Wind power is clean and plentiful, and an aerogenerator does no damage to the environment.

Water can provide power in three ways: wave, tidal and hydroelectric. Wave energy is plentiful. But wave power stations can potentially upset the local ecosystem. They must be carefully planned and sited where they will do little damage to marine and shore life. Tidal energy is harnessed by building a barrage across a river with a large tidal range – that is, a large difference between high tide and low tide. However, there are very few suitable sites for tidal power station. Solar power is energy generated from the sun. Many electronic devices can use the sun’s energy directly to provide the power they need.

4.3. Nuclear power. Nuclear (or atomic) energy comes from the energy stored within the nuclei of atoms, which are the basic building blocks of all matter.

There are several arguments for using nuclear power as a source of energy. First, the earth contains a limited supply of fossil fuels. Second, fossil fuels are very harmful to the environment. Nuclear power does not add to the greenhouse effect. Third, the earth contains a large supply of natural uranium. Nuclear power could, theoretically, supply all the world’s energy needs for thousands (and possibly millions) of years. Fourth, nuclear power comes to the consumer as electricity, which is clean and convenient form of energy. Last, although the capital investment is high, the cost of generating electricity from an established nuclear power station is relatively low.

However, there are many reasons why nuclear power is not the best source of energy. First, there is the danger of nuclear war. Second, even “peaceful” nuclear power is a danger to health. The radiation released when atoms split causes cancer and birth defects. Third, there are the problems of nuclear reprocessing and nuclear waste.