ENERGY SOURCES

throughout history people have obtained energy fromm their own muscles, animals, the wind, running water, several types of fuel. wood, coal, oil, petroleum,etc. and electricity of course traditional sources of energy are still being used.
EXAMPLE:
muscular energy in order to carry out certain tasks animals for pulling cards ploughing the land in developing countris; air currents for sailing boats,wind farms; running water for hydroelectric power stations, river boats; fuel for cars, gas or coal boilers; electricity for household electrical appliances, industrial machinary.