Renewable energy sources:
“Renewable energy sources are those energy sources that can be regenerated quickly.”There are many sources of energy such as coal,oil and natural gas.These fuels are called fossil fuels.These fuels would not last forever.They are not recoverable.These sources are called non renewable energy sources.
The shortage of fossil fuels will create serious energy problems.We must look for alternative sources of energy that can be recovered.These sources are called renewable energy sources.Renewable energy sources include wood,wind,water,animal wastes,sunlight and tides of sea.Some common renewable energy sources are given below:
- Energy from tides
- Energy from waves
- Energy from biomass
- Energy from waste products
- Geothermal energy
- Solar energy
- Wind energy
One very novel example of obtaining energy from gravitational field is the energy obtained from tides.Gravitational force of the moon gives rise to tides in the sea.The tides raise the water in the sea roughly twice a day.If the water at the high tide is trapped in a basin by constructing a dam,then it is possible to use this as a source of energy.The dam is filled at high tide and water released in a controlled way at low tide to drive turbines.At the next high tide the dam is filled again and the in rushing water also drives turbines and generate electricity.
Energy from waves:
The tidal movement and the winds blowing across the surface of the ocean produce strong water waves.Their energy can be utilized to generate electricity.A method of harnessing wave energy is to use large floats which move up and down with the waves.One such device invented by professor salter is known Salter’s duck.
It consists of two parts:
- Duck float
- Balance float
The wave energy makes duck float move relative to the balance float.The relative motion of the duck float is then used to run electricity generators.
Biomass is a potential source of renewable energy.This includes all the organic materials such as crop residue,natural vegetation,trees,animal dung and sewage.Biomass energy or bio conversion refers to the use of this material as fuel or its conversion into fuels.
Energy from waste products:
Waste products like wood waste ,crop residue,and particularly municipal solid waste can be used to get energy by direct combustion.It is probably the most commonly used conversion process in which waste material is burnt in a confined container.Heat produced in this way is directly utilized in the boiler to produce steam that can run turbine generator.
This is the heat extracted from inside the earth in the form of hot water or steam.Heat within the earth is generated by the following methods:
Radio active decay:
The energy ,heating the rocks,is constantly being released by the decay of radioactive elements.
Residual heat of the earth:
At some places hot igneous rocks,usually within 10 km of the earth’s surface ,are in a molten and partly molten state.They conduct heat energy from the Earth’s interior which is still very hot.The temperature of these rocks is about 200 Cº or more.
Compression of material:
The compression of material deep inside the earth also causes generation of heat energy.
In some place water beneath the ground is in contact with hot rocks and is raised to high temperature and pressure.It comes to the surface as hot springs,geysers,or steam vents.The steam can be directed to turn turbines of electric generators.
wind has kinetic energy in it.A windmill is a machine which has blades.These blades move by the energy of wind.These blades move by the energy of wind.In recent years ,a wind mill is being used to produce electricity.A wind farm (consists of about 100 windmills) is used to generate electricity in great amount.
See also Solar energy: