Firewood and Fossil fuels like coal, petroleum and natural gas called fossil fuels, are non-renewable and limited in stock. Energy from the sun, wind and tides, nuclear energy, energy from the earth and from decayed organic matter are called non-conventional sources of energy. These are renewable, unlimited and eco-friendly.
The primary source of all energy on the earth is the sun and its heat or light is called solar energy. Solar energy is an inexhaustible and non-polluting form of energy.
A device called a solar panel is used to convert solar energy into heat and electrical energy. A solar panel is made up of a number of solar cells that absorb solar energy and convert it into electricity. Solar energy can be effectively used in tropical countries that receive abundant sunlight.
Wind is another natural source of energy that is inexhaustible and is a non-polluting, low-cost, safe and clean source of energy. The energy generated from winds is called wind energy.
In olden times, wind mills were used for grinding grain and lifting water. Today, wind mills are used to produce electricity. The major disadvantages of wind energy are that it contributes to noise pollution and can be harmful to birds.
The energy stored in the nuclei of radioactive elements like uranium and thorium is known as nuclear energy. Nuclear energy is produced when the nucleus is split apart and this phenomenon is known as nuclear fission. During nuclear fission, tremendous amount of heat and light energy is released.
The earth also has a considerable amount of heat energy stored inside it. This energy is called geothermal energy, where geo means earth and thermal means heat. This energy is clean and eco-friendly. Geothermal energy can be seen dissipated on the earth’s surface in the form of hot springs, natural geysers and volcanoes.
The gravitational pull of the moon and the sun and the rotation of the earth result in causing tides. Energy generated from tides is called tidal energy. It is a non-polluting and inexhaustible source of energy.
Another renewable source of energy is biogas which is produced from bio mass. Biomass includes wood from trees, matter from dead plants and animals, waste from other plants, animal dung and kitchen waste.
It can be used to generate electricity, light, heat, motion and fuel. Biogas is a low-cost source of energy, easy to operate, and uses bio-waste.