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Where do we get energy from? We getenergy from the food we eat. A substancethat produces energy on burning is calleda fuel.Hence , food can be thought of as a fuelfor our body.
TYPES OF FUELS Fuels are available in solid , liquid or gaseous form. Wood , coal , coke and cowdung cakes are some examples of solid fuels. Liquefied Petroleum Gas (LPG), Compressed Natural Gas (CNG) and biogas are examples of gaseous fuels. Kerosene, petrol and diesel are examples of liquid fuels.
USES OF FUELSFuels produce energy on burning. Energy isrequired for many purposes. For producingenergy, different types of fuels are used indifferent situations.
DOMESTIC FUELS Cowdung cakes, coal and kerosene are commonly used domestic fuels. These fuels are used even now, in some households in villages. In cities , and in many villages, gaseous fuels like LPG and biogas are now commonly used as domestic fuels. These are cleaner fuels as they do not produce smoke on burning and do not leave any ash after burning.
FUELS FOR TRANSPORTATION AND ELECTRICITY GENERATION Trains were earlier run with the help of steam engines. In these engines, steam was produced by burning coal. Nowadays, train engines use either electricity or diesel.
Vehicleslike buses, cars, scooters, trucks and tractors run onpetrol or diesel.Many buses and cars now use CNG as fuel. CNG is called a green fuel because it causes less airpollution and is more eco-friendly. Aeroplanes use highly refined petrol as fuel.
DO YOU KNOW?Electricity, generated by using the energy ofwater, falling from a height, is called hydro-electricity.
FUELS AND MACHINES• Earlier, household works like washing clothes, spinning, weaving, and so on were done manually. This was time consuming, slow and tiring.• Hand-operated machines were then developed to help us. Later on, machines working through steam were invented.
This resulted in an increase in the demand for coal. Thereserves of coal, in nature, started depleting rapidly. To meet these challenges, steam engines were graduallyreplaced by other engines which used liquid fuels like petroland diesel. However, petroleum reserves in nature are also limitedand cannot be replenished easily.
FOSSIL FUELS• Fossil fuels are fuels that are formed by decomposition of animal and plant matter, buried deep under the surface of earth, at high temperature and pressure.• This animal and plant matter changes into fossil fuels over a period of millions of years. Coal, petrol and diesel are fossil fuels.
RENEWABLE AND NON-RENEWABLE SOURCES OF ENERGY.• Sources of energy, which once used, cannot be readily replenished are called non-renewable sources of energy. Coal and petroleum are non-renewable sources of energy.• There are some sources of energy which are freely available and which can be readily replenished. They are called sources of energy. Solar energy, water, wind and biomass are examples of renewable sources of energy.