What is Energy ? | Sources Of Energy | Conservation Of Energy


What is Energy ?

What is Energy : energy is the ability to do work. Without energy , one cannot move or speak . Energy helps the sun to shine , the birds to fly , the wind to blow , the vehicles to move , etc.

Sources of Energy

Energy can never be created and can never be destroyed . Then , where does the energy come from ? Main Sources of energy can be divided into two groups : renewable and non-renewable.

Renewable sources is an energy sources that can be replenished in short period of time

Non-renewable sources is an energy sources that we cannot recreate in a short period of time.

Renewable energy sources

These include solar energy , wind energy , geothermal energy from inside the Earth , biomass from plants , hydro power from water and ocean energy.

Solar energy : Almost all energy comes from the sun . The sun warms our planet and makes plants grow. Plants can use sun energy to make energy stores. These plants are eaten by animals and human beings. Our wastes product finally goes to plants where they start the cycle again using the energy from the sun.

Solar energy is used to heat water by solar water heaters which can be stored in big tank. It is also used to heat houses in cold countries.

Biomass : Wood comes from trees which have got energy from the sun . When trees are cut down and burnt , they release their energy in the form of heat. However burning wood causes a lot of air pollution.

Hydroelectric energy : By using the energy from falling water , hydroelectricity can be produced. The water comes from big dams across rivers , and flows down moving a turbine which is used to drive electric generators.


Wind energy : It is the energy of moving air . This energy is used by windmills to generate electricity or draw water from underground.


Geothermal energy : It is the energy obtained from the hot interiors of the Earth.


Tidal energy : This energy wroks by using the power of changing tides. A dam is built to trap the moving sea water as the sea goes up and down twice a day due to tides. It can be used to drive generators too.

Biogas : It is a gas obtained from human sewage and animal wastes. It is used for cooking , heating and lightning purposes , particularly in villages . It is also called gobar gas.

Non-renewable energy sources

Fossil fuels : petroleum , natural gas and coal are called fossil fuels because they have formed millions of years ago by the action of heat from Earth’s core and pressure from rocks and soil on the remains of dead plants and animals . Most of the energy used is fossils fuel energy. But they are limited in stock.

Nuclear energy : It cones from uranium and produces more energy than any other sources of energy . It is produced in a nuclear reactor.

Conservation of energy

  1. It is the energy at a rapid rate. If this trend continuous , fossil fuel will run out completely in a few years . Moreover , they do damage too. So, we should consume energy judiciously.
  2. When coal is burnt , it gives out carbon-dioxide , the gas responsible for global warming.
  3. Burning coal also produces sulphur and Nitrogen gas that can pollute both air and water . When these gases combine with moisture in the clouds ,they from acid rain


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