INTRODUCTION. Energy means ability to do work.

TYPES OF ENERGY. There are two types energy. Potential energy And kinetic energy. Energy can be converted From one form to another. But once fuels are used, it is not possible to get back fuels from the forms of energy. We get most of the energy required by us from fuels and electricity. Solar energy is also available to us in the form of a variety of fuels. Coal petroleum and natural gas are fuels. In this chapter we shall learn about different sources of energy types of fuels and why we should use them judiciously.

SOURCES OF ENERGY- RENEWABLE AND NON RENEWABLE. The energy of flowing water, wind. Tides and biogas are examples of some sources of energy that come directly or indirectly from the sun. The sources of energy derived from solar energy are available to us as long as we continue to receive light and heat from the sun. These are known as renewable sources. Non renewable sources have formed through a series of processes that have taken place over millions of years. Once these fuels are used will not be available again.

TYPES OF FUELS. Fuels are of three types solid, liquid and gases. SOLID FUELS Commonly used solid fuels in our country are fire wood, charcoal, cow-dung cakes, agricultural wastes and coal, Traditional chulas used do not completely burn fire wood, cow-dung cakes and other agricultural wastes. Coal is another important solid fuel used in cities, industries and power stations. Coal contains mainly carbon and is used to heat water in industries.

Calorific value of some solid fuels. FUEL CALORIFIC VALUE OF SOME SOLID FUELS. Cowdung cake Wood Coal

Liquid Fuels. The most commonly used liquid fuel in our homes is kerosene.Other liquid fuels are petrol,diesel and fuel oil.All these fuels occur in a liquid are obtained from petroleum, also called crude oil.Petroleum means oil from rocks.Petroleum is also called a fossil fuel.Different constituents,such as petrol,diesel,kerosene and petroleum gas.

Calorific value of some liquid fuels. FUEL CALORIFIC VALUE Kjoule per kgram. Petrol Kerosene Ethenol 30000

GASEOUS FUELS. Petroleum gas and natural gas are two common gaseous fuels. Petroleum mainly consists of a gas called butane. It also contains ethane and propane. All these gases are hydrocarbons. Butane is easily liquefied. Therefore it is supplied in liquid form in cylinders.Natural gas is another fossil fuel that is found with petroleum in oil.Methane is also a hydrocarbon.Another gaseous fuel is biogas.

RENEWABLE SOURCES Sun is the most important source of energy. At any point of time, one part or the other of the earth’s surface is illuminated by sunlight. So we can say that the earth receives the energy from the sun in the form of heat and light throughout the year, twenty- four hour a day. Absorption of heat by the land and water on the surface of the earth gives rise to many natural phenomena, like blowing of wind, rain and snow. The solar cookers are used to cook food,

Solar cell convert solar energy into electricity.They are usually made of silicon. Solar cells are used to generate electricity in satellites and in far off areas such as ladakh. On a limited scale, these are also used in calculators, traffic lights and for the transmission of radio and television programmes from remote areas. At present, the cost of solar cells is high and this prohibits their widespread use.

W ind energy - winds are convection currents in the air cause by the uneven heating of the earths surface by the sun. The wind direction and its speed keeps on changing throughout the ear at every place on the earth.The speed of wind usually increases with height. Wind speed is also greater over the sea and in costal areas. The wind energy has been used for running windmills for many centuries in some countries,especially in Europe.The energy output from all wind mills are coupled together to get electricity on a commercial scale.

HYDROELECTRIC ENERGY Nowadays, the energy of flowing water is used for generating electricity in hydroelectric power plants Biogas In the absence of air, the plant and animal material in the presence of water decompose to give methane, carbon dioxide and some other gases. This mixture of gases is know as biogas. Biogas is a good fuel for cooking.

N UCLEAR E NERGY When the nucleus of a heavy atom (for example, uranium) splits into lighter nuclei, large quantities of energy is released. This process is called nuclear fission and the energy produced is known as nuclear energy or atomic energy. Another kind of nuclear reaction is called nuclear fusion. In nuclear fusion, In nuclear fusion, light nuclei fuse to form a larger nucleus.

Prepared By: Sanjukta Acharya Asst. Teacher Hindol High School, Hindol

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