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Solar Energy
The whole world is greatly concerned about tremendous increase in demand of energy and consequent depletion of convention energy sources like wood, coal oil etc.
"At the present rate of energy consumption, the reserve of fossil fuels of the entire world can be exhausted in 50 to 100 years," said Dr. M. N.
Nahar, principal scientist of the Division of Agriculture and Energy at the Central Arid Zone Research Institute
(CAZRI). "There is an urgent need to harness solar energy and other alternative energy sources."
solar thermal collectors
Unlike natural gas, coal, or nuclear power, solar power requires no fuel, works without polluting the air or leaving behind dangerous
radioactive waste, and is extremely plentiful. Researchers estimate that the sun produces enough energy in a single second to meet the
needs of all humanity for 2000 years. "The surface of the Earth receives an amount of solar energy equivalent to roughly 10,000
times the world energy demand," wrote Erik Lysen in the January 2003 issue of Renewable Energy World magazine.
India receives about 300 clear sunny days in a year. This is equal to over 5,000 trillion kWh/year, which is far more than the total energy
consumption of the country in a year The daily average solar energyincident over India varies from 4-7 kWh/m2, depending upon location.
India needs solar energy
According to the prime minister, success in developing solar energy 'will change the face of India. It would also enable India to help change the destinies of
people around the world. The plan intends to go beyond government to draw upon these assets'.
India's plan to build 'solar cities' evolved from the prime minister's mission to build a 'green India'.
India, where most regions enjoy nearly 300 sunny days a year, is an
ideal market for solar power companies. However, the high cost of light-to-electricity conversion -- at Rs 12 to Rs 20 per kWh
(kilowatt-hour) -- has acted as a deterrent so far.
SPV systems
SPV systems have found applications in households, agriculture,
telecommunications, defense, and railways among others. In the last two decades, the cost of PV has gone down by more than 10
times, increasing accessibility for dispersed rural applications.Costs are expected to reduce further thus creating more
potential About 62 MW aggregate capacity (about 10,50,000 individual PV systems and power plants) have been installed for various
applications. In addition, PV products of 48 MW capacity have been exported.
Under MNES's PV programme, around 8.20 lakh systems have been installed - aggregating to about 29 MW. This includes 509,894
solar lanterns, 2,56,673 home lighting systems, 47,969 street lighting systems, and 5,000 water pumping systems. About 3.97 MWp of aggregate capacity of stand-alone and
grid interactive PV power plants have been installed as on March 31, 2003. These include State's own programmes also MNES is implementing two major
schemes for the deployment of stand-alone PV systems in the country: |
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Lighting systems, stand-alone power plants and other specialized systems, implemented mainly through
SNAs/departments/corporations, Aditya solar shops operated by Manufacturers Associations and NGOs.
Water-pumping systems for agriculture and related uses, implemented through IREDA and SNAs West Bengal, Rajasthan, hilly regions of Uttar Pradesh, Ladakh,
Lakshadweep, Andaman and Nicobar Islands are prominent regions where SPV home lighting systems and power plants are in demand.
About 3600 remote villages and hamlets have been electrified with SPV systems and power plants. Out of these 800 remote villages
have been electrified during 2001-02 and 2002-03.Eleven power plants of 250 kWp aggregate capacity have been
installed in Sagar Islands in West Bengal Aims and
Targets. A wide range of power technologies exist which can make use of the solar energy reaching Earth.
Indian government planning to develop
solar cities
Indian government announced recently that it was planning to develop
solar cities to reduce about 10 per cent usage of conventional energy sources through renewable energy installations and energy efficiency.
During the 11th Plan period, a total of 60 cities are proposed to be developed as solar cities, based on a model already practised in New
York in the United States, Tokyo in Japan, and London in Britain.
India too targets a 10 to 20 per cent carbon emission reduction in the next 10 to 20 years.
Under the government's solar city scheme, each of the 60 urban local
governments would be provided a total of Rs 50 lakh (Rs 5 million) assistance of which Rs 10 lakh
(Rs 1 million) would be for preparation of a master plan, Rs 10 lakh (Rs 1 million) for setting up a solar cell
in the city council, Rs 10 lakh (Rs 1 million) for implementation of the plan over five years and the remaining Rs 20 lakh (Rs 2 million) for
other promotional activities. A target of 50 MW has been set for solar power generation during the
11th Plan, which is likely to be achieved. India receives solar energy equivalent to over 5,000 trillion kilowatt hour per year.
In February 2009, government announced that Nagpur in Maharashtra will
be developed as India's first solar city. Nagpur, the 'Orange City', will become a model solar city by 2012,
deriving up to 10 per cent of its energy consumption through renewable
energy sources and implementing other energy efficiency measures, a
government statement said.
The city can also opt for additional funding from the ministry if the project cost goes beyond the estimates.
Solar energy systems, including street lights, garden lights, traffic lights, hoardings and solar water heaters will be installed in the city.
Energy efficient 'green buildings' will be promoted on a large scale.
According to New and Renewable Energy Minister Farooq Abdullah, his
ministry is implementing a programme on development of solar cities aimed at reducing minimum of 10 per cent of the projected demand of
conventional energy of the city through energy efficiency measures and renewable energy installations.
Abdullah had said the centre was providing financial support up to Rs 50
lakh (Rs 5 million) for each solar city to the respective state governments for preparation of a master plan, awareness generation.
Method of energy transformation
A photovoltaic cell produces electricity directly from solar energy.
Direct solar power involves only one transformation into a usable form. For example:
Sunlight hits a photovoltaic cell (also called a photoelectric cell) creating electricity.
Hydroelectric power stations produce indirect solar power. The Itaipu Dam,
Brazil /Paraguay Vegetation uses photosynthesis to convert solar energy to chemical energy, which can later be burned as fuel to generate electricity.
Methane (natural gas) and hydrogen may be derived from the biofuel. Hydroelectric dams and wind turbines are powered
by solar energy through its interaction with the Earth's atmosphere and the resulting weather phenomena. Ocean thermal energy production uses the thermal
gradients that are present across ocean depths to generate power. These temperature differences are ultimately due to the energy of the sun.
Solar technologies: Most solar energy used today is harnessed as heat or electricity.
Solar design is the use of architectural features to replace the use of grid
electricity and fossil fuels with the use of solar energy and decrease the
energy needed in a home or building with insulation and efficient lighting and appliances.
Insulating shutters for windows to be closed at night and on overcast days. These trap solar heat in the
building. Fixed awnings positioned to create shade in the summer and exposure to the sun in the winter.
Movable awnings to be repositioned seasonally. A well insulated and sealed building envelope. Active thermal solar
panels using a heat transfer fluid (water or antifreeze solution). These are heated by the sun and the heat is carried away by
circulation of the fluid for domestic hot water or building heating or other uses.
Solar heating systems: Solar heating systems are generally composed of solar thermal collectors,
a fluid system to move the heat from the collector to its point of usage, and a
reservoir to stock the heat for subsequent use. The systems may be used to heat
domestic hot water or a swimming pool, or to provide heat for a heating circuit
. The heat can also be used for industrial applications or as an energy input for other uses such as cooling equipment.
Solar thermal cooling: There are some new applications of thermal hot water, such as air cooling,
currently under development. The absorber machine works like a refrigerator.
It uses hot water to compress a gas that, once expanded, will produce an endothermic reaction, which cools the air.
Concentrated Solar Power (CSP) Plants: A concentrating solar power
plant, Parabolic trough power plants are the most successful and cost-effective CSP system design at present.
Solar chimney: A solar chimney is a relatively low tech solar thermal power plant where air
passes under a very large agricultural glass house (between 2 and 30 km in
diameter), is heated by the sun and channeled upwards towards a convection
tower. It then rises naturally and is used to drive turbines, which generate electricity.
Energy Tower: An Energy tower is an alternative proposal for the solar chimney. The "Energy
Tower" is driven by spraying water at the top of the tower; evaporation of water
causes a downdraft by cooling the air thereby increasing its density, driving
wind turbines at the bottom of the tower. It requires a hot arid climate and
large quantities of water, but it does not require a large glass house.
Solar pond: A solar pond is a relatively low-tech, low cost approach to harvesting solar
energy. The principle is to fill a pond with 3 layers of water.
Solar chemical: Solar chemical refers to a number of possible processes that harness solar
energy by absorbing sunlight in a chemical reaction in a way similar to
photosynthesis in plants but without using living organisms. No practical process has yet emerged. |
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Solar cooking: A solar box cooker traps the Sun's power in an insulated box; these have been
successfully used for cooking, pasteurization and fruit canning. Solar cooking
is helping many developing countries, both reducing the demands for local
firewood and maintaining a cleaner environment for the cooks. The first known
western solar oven is attributed to Horace de Saussure.
Solar Cooker
Solar lighting: The interior of a building can be lit during daylight hours using fibre optic
light pipes connected to a parabolic collector mounted on the roof. The
manufacturer claims this gives a more natural interior light and can be used to reduce the energy demands of electric lighting.
An NRI etting up solar power plants in Nagpur
An NRI Ravi Pradhan unveiled a plan in Nagpu to build a 5MW photo voltaic plant
and, subsequently, a solar thermal power plant with up to 50 MW generating capacity.
Pradhan, the founder of the company, did his schooling here and later graduated in mechanical engineering from
VNIT. Starting his career with Hindustan Motors, Pradhan later shifted to the US where he did his post graduate studies and worked for top American
companies, including Bechtel, which is a global player in solar energy technology. He is one of the few experts in nuclear energy field and
hopes to contribute in the sector which has thrown open after the Indo-US nuclear pact signed last year. “The over-dependence on fossil
fuels has led to problems of climate change, greenhouse gasses and pollution. |
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