Renewable energy sources are called non-conventional energy sources. A renewable energy system converts energy found in sunlight, wind, falling water, sea waves, geothermal heat, biomass into a suitable form of energy. The renewable source can never be exhausted. Various forms of these energies are:
- Solar Energy
- Wind Energy
- Hydro Energy
- Bio Energy
- Geothermal Energy
- Ocean Energy
Solar Energy
The sun is the most abundant and unlimited source of energy. Energy from the sun is known as solar energy. This energy has very high potential. As a result, solar energy is one of the most important non-conventional sources of energy in India. Solar energy is useful in a number of ways. The solar cookers are used for cooking of food with practically no fuel cost. Solar concentrators can be used to produce steam for driving electric generators. Solar cell converts solar radiation into electrical energy by photoelectric effect. A large number of cells are connected in series/parallel to form a photovoltaic panel that are used to generate electrical energy on large scale.
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Wind Energy
Movement of atmospheric air is called wind. It has kinetic energy. About 1 to 3% of the solar energy falling on earth gets converted into wind energy. Wind energy is a popular form of non-conventional energy source. It is used for drawing water, which is an essential requirement in watering agricultural lands in the rural areas. Even, it can be utilized for electricity generation. In India, some states like Tamil Nadu, Gujarat, Odisha, and Maharashtra are regarded as superior areas with respect to this type of energy. Places that have regular and rapid wind flows are suitable for this kind of power generation.
Read More - Wind Energy and Wind Turbine
Small Hydro
Water is about thousand times heavier than air. Even a slow flowing water stream produces large amount of energy. Energy captured from falling water is called hydro energy. Small hydro power is considered as renewable or non conventional energy sources. Small quantity of water with high head as in case of hilly region and small quantity of water with low head as in case of canal can be tapped. The force of flowing and falling water is used to drive water turbine to generate energy.
Small hydro schemes are classified as micro hydro upto 100 kw plant capacity, mini hydro from 101 kW to 1000 kW and small hydro upto 25,000 kW plant capacity. The advantage of this scheme is that it can be harnessed almost everywhere in India from any nearby water stream or canal without causing submergence, deforestation or resettlement problem. The main advantage of these plants is high efficiency and long life. It is also cheapest, and cleanest source of energy. Civil works and installation of equipments need simple process and it employs local people and use locally available materials. Also gestation period is short.
India has a large potential of small hydro power of about 15,000 MW. The 130 KW small hydropower plant in Darjeeling set up in 1897, was the first in India. There are more than 4,000 potential sites of small hydro power in India and its development will reduce load on conventional sources of energy. So far, about 500 small hydro projects with a total capacity of 4,055 MW have been installed till March, 2015.
Bio-energy
1. Biomass: Biomass is an important source of energy which represents approximately 40% of the overall volume of fuel used in the country. It is broadly utilized in domestic circles for preparing food and warming. In rural areas, farming wastes, timber, wood, raw charcoal can be used as biomass. Many initiatives have been taken in India to make the right use of biomass in systematic way. The two principal segments of the biomass program are generation and usage of biomass.
2. Biogas: With the usage of agricultural and animal excretions over and above human body wastes, a number of 'Gobar Gas' plants have been built in many rural areas to make them self reliant in their energy requirements. The energy generated in this way is utilized for food preparation, lighting roads and houses, and satisfying the water supply requirements of the rural community. The plants have been established both at private and group levels.
The composition of biogas varies depending upon the origin of the anaerobic digestion process.
3. Biofuel: A new form of man-made fuel, which could be either bio-ethanol or bio-diesel. Both can be made by man using plant sugars or starch or animal fats/oil. While bio-ethanol and bio diesel can be used in its purest form as a fuel for vehicles, it is usually used as a gasoline/diesel additive.
Geothermal Energy
The core of the earth is very hot and it is possible to make use of this geothermal energy (in Greek it means heat from the earth). These are areas where there are volcanoes, hot springs, and geysers, and methane under the water in the oceans and seas. In some countries, such as in the USA water is pumped from underground hot water deposits and used to heat people's houses. Electric power generation from geothermal energy can be achieved through transfer of heat energy to a working fluid which operates the power cycle. Electric power can also be generated when hot geothermal water or steam is used to operate the turbines directly.
In India, North-western Himalayas and the Western Coast are considered geothermal areas. The Geological Survey of India has already identified more than 350 hot spring sites, which can be explored as areas to tap geothermal energy. The Puga valley in the Ladakh region has the most promising geothermal field. An experimental 1 kW generator is already in operation in this area. It is being used mainly for poultry farming, mushroom cultivation, and pashmina-wool processing, all of which need higher temperatures.
Ocean Energy
Energy from ocean and seas are obtained mainly in three ways ocean thermal, tidal and wave energy.
1. Ocean thermal energy: A large amount of solar energy is stored in the oceans and seas which absorb heat energy of solar radiation.
The surface water being directly exposed to solar radiation is heated more than that of deep ocean water. There a temperature difference of about 25°C exists between the surface of the ocean and the depths of about 1000 m to operate a heat engine, which produces electric power. The process of harnessing this type of energy is called OTEC (ocean thermal energy conversion). The surface water which is at a higher temperature could be used to heat some low temperature boiling fluid like ammonia, the vapours of which would run a heat engine.
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2. Tidal energy: Tides are a result of the gravity of the sun, the moon and the rotation of the earth, working together. These tides can be used to produce electrical energy which is known as tidal energy. Tidal energy is a limitless and renewable source of energy. For producing electrical power from tidal energy, dams are built so that inward and outward water flow are used to power turbines to generate electricity. A major tidal power project costing 5000 crores is proposed to be set up in the Hansthal Creek in the Gulf of Kutch in Gujarat.
Read More - Tidal Energy and its Phenomenon
3. Wave Energy: Waves are a renewable source of energy that doesn't cause pollution. Energy from waves alone could supply the world's electricity needs. The total power of waves on the world's coastlines is estimated at 2 to 3 million megawatts (terra watts).
Ocean waves are caused due to wind as it blows across the open expanse of water, the gravitational pull from the sun and the moon, and changes in atmospheric pressure, etc. Waves created by the wind are the most common waves relevant for most wave energy technology. Wave energy conversion takes advantage of the ocean waves caused primarily by the interaction of winds with the ocean surface. Wave energy is not regular oscillating low-frequency energy source. They are a powerful source of energy, but are difficult to harness and convert into electricity in large quantities. This energy needs to be converted to a 50 Hertz frequency before it can be connected to the electric grid.
At present, there are only a handful of wave generator plants in operation around the world.
Read More - What is Wave Energy? Wave Energy Generation and Wave Energy Conversion Devices
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