A racing car as you know has a petrol- driven engine. The petrol is a fossil fuel ultimately depending on the Sun`s energy, as we shall see. On a sunny day you can feel the Sun`s rays warming your face. The Sun is applying energy in the form of heat. Solid as it may look, the Sun is completely made up of gas, so that although the Sun`s volume is more than a million times greater than that of the Earth, its mass is only about 3,00,000 times greater. We are completely dependent upon energy from the Sun for our survival. If the Sun were to become only a little cooler we would freeze. It is worth remembering too that the Sun has shone for thousands of millions of years and will do so for thousands of millions more.
We have said that the Sun is composed of gas. In fact, there are two gases, called hydrogen and helium. When atoms of hydrogen join together to form helium enormous quantities of energy are released. This process is called fusion. Scientists are trying to perfect methods of fusion to provide some of the energy that we need in our homes and industries.
All life depends on the energy from the Sun to survive. We need to feed our bodies by eating such materials as meat and vegetables. Green plants, however, are able to make their own food by making use of the Sun`s rays as fuel for the manufacturing process. The colouring matter of green plants is a complex pigment called chlorophyll. This chlorophyll harnesses the energy of light and converts it into chemical energy. The plant takes in the gas, carbon dioxide, from the air and by means of the chemical energy, converts it into complicated sugars which it needs for growth. In fact, the plants are actually storing energy. When animals or man eat plants, they are able to make use of some of the energy stored by the plants, so that you can see how we depend upon plants for food. Under normal conditions, when plants and animals decay, their bodies decompose and the stored energy is lost to the surroundings or used by other living things. Under waterlogged conditions, however, a different process may take place. In bogs and swamps, for example, plant remains change into dark, jelly-like humus which may soak into any partly decayed twigs. The material becomes richer in carbon and an inflammable gas is given off. As the material becomes buried and subject to heat and pressure coal may be formed. At the bottom of the sea the remains of plants and animals may be converted into tiny drops of oil. These drops may then flow within the rocks until they become trapped by rocks through which the oil cannot pass and it then builds up. Oil and coal are referred to as fossil fuels because they are produced from the remains of plants and animals that have long since died. These fuels take millions of years to form and accumulate. Most of the world`s reserves of oil were formed between about 230 and ten million years ago.
It was discovered that certain parts of the natural or crude oil is highly inflammable, in other words, it could be made to release its stored energy. But first it had to be found and extracted by drilling a well and then it had to be refined to produce products such as petrol that we use to power our motor cars. Oil is often referred to as ‘black gold’ because so much of our modern way of life depends upon it and many people have become millionaires almost overnight by finding reserves of oil beneath the surface of the land that they own. We need oil to power our cars, to fuel electricity generating stations, in industry, and even to supply the basic materials to make plastics and other chemicals. The racing car requires a particularly high grade of petrol to fuel its powerful engines and millions of gallons may be burned every year in this way. You have seen that it takes a very long time for oil to form but we are using it at an alarming rate. Recently the rapidly increasing price of oil has led to the working of reserves that were once thought to be uneconomic. Scientists, too, are frantically searching for new forms of energy so that our precious reserves of oil may be conserved. But you can see how almost all of the energy we use or are likely to use, including the fuel for the racing car, ultimately depends upon the Sun`s rays.
What other kinds of energy can we use...?
You have seen in the previous question the stages through which the Sun`s energy passes before we can tap it as the fossil fuel, petrol. It has taken millions of years for the world`s reserves of oil to be built up and we have consumed much of it in a few decades. We need energy in our homes and in industry and for transport, but we also use crude oil to provide us with many of the chemicals upon which our way of life depends, so that scientists are working hard to find new ways of supplying the energy we have come to require. Some of the ways are not so new, new types of windmills have been constructed and there has even been a return to the horse on some farms. The force of the tides also can be harnessed to drive turbines which then generate electricity. We can tap the Sun`s energy directly by means of solar panels which convert the Sun`s rays into usable forms of energy.