The increasing use of fossil fuels is leading to its shortage. It is estimated that if the present rate of consumption continues, the reserves of these fuel will get exhausted. Moreover,their use also causes environmental pollution. Therefore, there is need for using non-conventional sources such as solar, wind, tides, geothermal heat, and biomass including farm and animal waste as well as human excreta. All these sources are renewable or inexhaustible and do not cause environmental pollution. More over, they do not require heavy expenditure. They are capable of solving the twin problems of energy supply in decentralized manner and helping in sustaining cleaner environment.
Types of Non-Conventional Sources of Energy:-
- Solar Energy
- Wind Energy
- Ocean (Tidal) Energy
- Wave Energy
- Geo Thermal Energy
- Biomass Energy
1.Solar Energy
Sun is the source of all energy on the earth. It is most abundant, inexhaustible and universal source of energy. All other sources of energy draw their strength from the sun. Solar energy can be used directly or indirectly for human welfare. The direct solar energy is the radiant
energy, whereas the indirect solar energy obtained from the materials such as biomass, in which sun’s radient energy has been incorporated by the plants.On global scale, 15 days of solar energy is roughly equivalent to the energy stored in all known reserves of fossil fuels on the earth. The continuous input of the energy from the sun is 1,67,000 times greater than the current consumption. As such, now many countries are in effort
to harness the solar energy for domestic, commercial or industrial purposes. Solar energy can be used for direct heating. Alternatively, the heat can be converted into the electricity- the thermal electric generation. Photovoltaic cells-the solar cells or solar batteries convert direct solar energy into electricity.
India is blessed with plenty of solar energy because most parts of the country receive bright sunshine throughout the year except a brief monsoon period. India has developed technology to use solar energy for cooking, water heating, water dissimilation, space heating, crop drying etc. The grid-connected capacity in the country now stands at 481.48 MW, while the total solar energy potential has been estimated at 50,000 MW.
2.Wind Energy
Wind power is harnessed by setting up a windmill which is used for
pumping water, grinding grain and generating electricity. Harvesting wind
energy is possible only in the areas that receive fairly continuous wind such as islands, costal areas and mountain passes. Areas with constantly high speed preferably above 20 km per hour are well-suited for harnessing wind energy.When gigantic fans, raised on tall towers, are rotated by the wind, rotate wind turbines. These turbines cause the rotation of magnets, which creates electricity. Wind power is a renewable energy source, which has no waste by products, and causes no pollution. But it is quite ‘unpredictable’. When wind speed is low, less electricity is generated.The gross wind power potential of India is estimated to be about 20,000 MW.
India occupies the fifth position, after Germany, USA, Denmark and Spain, in wind power generation adding 2483 MW to the power sector. Gujarat is the first state in the country to start using wind power. Wind mills are used in Rajasthan to draw subsoil water for irrigation. Recently two wind farms of 10 MW each have been established in Tamil Nadu and Gujarat with international cooperation from Denmark.
3.Ocean Energy
The ocean forms a vital source of energy. Ocean energy is obtained in various forms such as ocean tidal and wave energy, ocean thermal energy conversion etc.
a) Tidal energy
Sea water keeps on rising and falling alternatively twice a day under the influence of gravitational pull of moon and sun. This phenomenon is known as tides. Tides are a source of clean and renewable source of energy. But the energy generation may have serious environmental impacts like water salinity and sediment movement. Tidal power or tidal energy is a form of hydropower that converts the energy of tides into electricity. A water turbine is placed in a tidal current, which turns an electrical generator, or a
gas compressor that stores the energy until needed. It is estimated that India possesses 8000-9000 MW of tidal energy potential. The most potent sites to produce tidal energy include the Gulf of Cambay (7000 MW approx.) and Gulf of Kuchchh (1200 MW approx.) on the west coast, and the Ganges Delta in the Sunderbans in WestBengal (less than 100 MW).
b) Ocean Thermal Energy Conversion (OTEC):
The sun warms the oceans at the surface and wave motion mixes the warm water downward to depth of about 100 meters and this mix layer is separated from the deep cold water formed at a high latitudes, by a thermocline. This boundary is sometimes marked by an abrupt change in temperature, more often the change being gradual. Thus, the resulting temperature distribution consists of two layers separated by an interface with temperature differences between them ranging from 10 ºC to 30 ºC. The higher values are found in equatorial waters. And these two enormous reservoirs in some oceanic regions provide the heat source and heat
sink required to operate the heat engine. The engine using this energy is referred to as OTEC which makes use of the difference in temperature between the two layers of the sea to harness energy which in turn is used to drive turbines for generating electricity.
The concept of OTEC was first demonstrated in 1979 when a small plant mounted on a barge off Hawai, USA produced 50 KW gross power. India possesses a huge potential of OTEC which could be of the order of about 500,000 MW, about 150 percent of the present total installed power generation capacity of the country. Some of the best global OTEC sites are situated off the Indian mainland and near the islands of Lakshadweep, Andaman and Nicobar.
4.Wave Energy
Wave power systems convert the motion of the wave into usable mechanical energy, which in turn, can be used to generate electricity. These systems can be floating or fixed to the seabed offshore, or may be constructed at edge on a suitable shoreline. The incessant motion of the sea surface in the form of water waves caused by wind constitutes a source of energy. About 1.5 % of the incoming energy from sun is converted to wind energy. Part of this is transferred to the sea surface resulting in the generation of waves.
This then is carried to coastal lines where it is dissipated as the waves break. Extract of energy from waves is more efficient than direct collection of power from wind, since the wave energy is concentrated through the interaction of the wind and the free ocean surface. For india whose coastal line extends to about 6000 km in length the annual wave energy potential is estimated to be about 60000 MW approximately (between 5MW to 15 MW per meter). India has initiated the wave energy project near Trivendrum in Kerla as an indigenous effort. It was expected that on the completion, the project would be able to derive an energy output of 4.45 lakh units per year. The project resulted in a strict reality in 1991 when it started generation of electricity to be fed to the grid of Kerla State Electricity Board. It is estimated that wave energy potential along the Indian coast is.
5.Geo-Thermal Energy
Heat energy obtained from the earth is called geothermal energy. The temperature in the interior of the earth rises steadily as we go deeper. Some times this heat energy may surface itself in the form of hot springs. Geothermal energy in the form of hot springs has been used for cooking, heating and bathing for several years. This heat energy can be used to generate power. The natural heat from the interior of the earth can be converted into energy. This natural heat comes from the fission of radioactive material present in the rocks in the interior of the earth.
The idea of harnessing geothermal energy, utilizes dry steam, was developed in Italy as early as in 1904. Natural internal heat of the earth was harnessed by geo-hydro-thermal conversion, hot igneous and geo-pressured systems. Heated groundwater flowing upwards as hot water stream and hot springs- nature’s geysers, can be used to turn turbines and generateselectricity.USA has the world’s largest geothermal power plants followed by New Zealand, Iceland, Philippines and Central America.
In India, geothermal plants are located in Manikaran in Himachal Pradesh and Puga Valley in Ladakh. Assessment of geothermal energy potential of selected sites in Jammu and Kashmir, Himanchal Pradesh, Uttarakhand, Jharkhand and Chhattisgarh is being undertaken. Some more field investigations, including deep drilling at potential geothermal sites, would be required before these sites can be taken up for developmentfor geopower generation.
6.Energy from Biomass
Biomass generally refers to the organic matter generated by plants through
photosynthesis, wherein solar energy combines with CO2 and moisture to form carbohydrates and oxygen. Materials having combustible organic matter are referred to as biomass. Biomass contains C, H and O which are oxygenated hydrocarbons. It generally contains a high level of moisture and volatile matter but has a low bulk density and calorific value. Biomass refers to all plant material and animal excreta when considered as an energy source. Some important kinds of biomass are inferior wood, urban waste, bagasse, farm animal and human waste. Coal is the end product of a sequence of biological and geological processes that biomass undergoes.
Biomass energy is the utilization of energy stored in organic matter. It is humanity’s oldest external source of energy, dating back to prehistoric man’s first use of fire. And biomass is still an important part of the world’s energy system; the use of traditional biomass—charcoal, firewood, and animal dung—in developing countries accounts for almost 10% of the world’s primary energy supply.
6.1 Biomass is an attractive energy source for a number of reasons:
1.Biomass is a renewable energy source generated through natural processes and as abyproduct of human activity.
2.It is also more evenly distributed over the earth’s surface than fossil fuel energy sources,and may be harnessed using more cost effective technologies.
3. It provides us the opportunity to be more energy self-sufficient and helps to reduce climate change.
It helps farmers, ranchers and foresters better manage waste material, providing rural job opportunities and stimulating new economic opportunities.
6.2 Bioenergy can be utilized in varied appications:
1. Biomass can be combusted to produce heat (large plants or localized biomass boilers),electricity, or used in combined heat and power (CHP) plants.
2. Biomass can also be used in combination with fossil fuels (co-firing) to improve efficiency and reduce the build up of combustion residues.
3.Biomass has potential to replace petroleum as a source for transportation fuels.
Biomass is also used in conjunction with fossil fuels for electricity generation in “waste-to-energy” projects. These are niche applications, which depend on the biomass having no other commercial value and being in close proximity to the application.Organic waste such as dead plant and animal material, animal dung and kitchen waste can be converted into a gaseous fuel called biogas. The organic waste is decomposed by bacteria
in biogas digesters to emit biogas which is essentially a mixture of methane and carbon dioxide.Biogas is an excellent fuel for cooking and lighting and produces huge amount of organic manure each year. Energy is everywhere but we can see that harnessing this energy is both difficult as well as costly. Each one of us can make a difference by not wasting energy. Energy
saved is energy generated. Act now and make brighter energy future.
6.3 Sources of Biomass:
1.Field and plantation biomass:
A.Agricultural crop residues-Cobs, stalks, Straw, Canethrashes and etc
B.Edible matters from crops-Environmentally spoiledgrains, pulses, fruits, nuts,spices, seeds and lint etc
C.Dedicated energy crops-Bamboo, Prosopis,Casuarinas, Willow andpoplar etc.
D.Plantation debris-Leaves,stubbles, barks and trunks etcLivestock wastes from fields,slaughter houses and animal
husbandries etc.
2.Industrial biomass:
Agro-industrial processed biomass and their wastes: HuskOil cake Sugar bagasses Sugar molasses, Whey Hides and skin wastes Fruit and pulp debris
Saw dust Wood pulp and paper shavings Fermented microbial mass etc.
3.Forest biomass:
Timber,Log residues,Forest floor,debris,Animal,carcass.
4.Urban waste biomass:
Municipal solid wastes Sewage sludges Kitchen and. canteen wastes.
5.Aquatic biomass:
Microalgae blooms Sea weeds (E.g. Kelp) Fresh water weeds (E.g. Water Hyacinth) Dead fishes.
India is the 7th largest country in the world spanning 328 Million hectares and amply
bestowed with renewable sources of energy. It has been estimated that India produces about 450
million tonnes of biomass per year, of which about 200 million tonnes is surplus. Biomass tops
the list in providing 32% of all the primary energy use in the country.
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