- Renewable & Alternative Energy
Renewable Energy Solar Power
What is Solar Power and Why do we need the Renewable Energy Solar Power
The sun provides enormous amount of energy which is released due to the process of fusion going on in the sun. This energy can be harnessed and used.
- Advantages of using solar energy: It is Useful in remote operations like satellites, It is obviously pollution free, The cost of maintenance is low, and It is decentralized source of energy.
- Disadvantage of using solar energy: Disadvantages include a few like the involvement of high initial or installing cost and also during winter seasons energy tapping would definitely weakens.
Methods of Tapping Solar Energy
Presently solar energy is being utilised through two different routes, namely, Solar Thermal Route and Solar Photo-Voltaic Route.
What is Thermal method
Under this method, Solar energy is converted into heat by means of concentrators such as blackened sheet, multi-reflectors, etc. Solar cookers, solar water heaters, solar desalination plants, solar air heaters and solar steam generators are designed to work on solar thermal energy. Temperatures ranging from 90 degrees C in solar cookers to 3000 degrees C in solar steam generators can be attained by using special concentrators, depending on the type of application.
What is Photovoltaic Power
Under this method, solar energy is directly converted into electricity as certain materials such as silicon, compounds of aluminium, arsenic and gallium when coated with impurities like phosphorus, boron, etc. and exposed to sun rays release a stream of electrons producing electricity. This technology is known as photovoltaic technology.
Solar photovoltaic systems have a wide range of applications such as lighting, water pumping and telecommunications. The most important of the applications is its use in outer' space to run the transmission devices installed in the artificial, satellites. They are particularly useful for rural and isolated areas. Solar refrigeration is used to preserve vaccines and medicines. Also, solar battery chargers are used by defence personnel for communication in remote areas.
A solar cell is essentially a semiconductor device processed and fabricated in a manner which permits generation of electricity when light falls on it. Silicon is the most commonly used material in the production of the solar cells. India is one of the six countries which have developed the technology for manufacture of poly-silicon material.
What are the limitations in using Solar Energy
The generation of electricity from solar energy, although technically feasible is yet to reach the stage of commercial viability. At the prevailing cost of solar cells, the cost of installations as well as the cost of production of electricity from solar energy is very high compared to the cost of electricity produced from other conventional sources.
Solar thermal power programmes in India include popularisation of solar cookers, water heaters, desalination devices, and air heaters. Solar water heating systems have become relatively more popular in India. World's largest solar steam cooking system was installed successfully at Tirumala, Andhra Pradesh, catering to cook two meals for 15,000 people daily. The system saves an equivalent of one lakh litres of diesel per year. The 2nd largest deployment of these systems is at Talati in Mount Abu catering to 10,000 persons. Similar system is being set up in Shirdi Sai Baba Samsthan in Andhra Pradesh to cater to 3000 persons.
What is Solar Pond
It is a pond with the capability to convert solar radiation into heat energy, which is then utilized for various purposes.
Method: The water (like any fluid) becomes lighters, i.e. less denser, when subjected to high temperatures. In any normal water pond, when the water is heated due to solar radiation it becomes lighter and rises from the bottom of the pond to the surface and then loses its heat to the atmosphere. Thus, the water in a normal pond remains at the atmospheric temperature.
But in a solar pond, salt is dissolved in the bottom layer of the pond. This makes the water in the bottom layer heavy and therefore does not have hot water to rise to the surface. Thus, the heat is entrapped in the pond itself.
In fact, solar pond consists of three zones. The top zone has little salt content and is at atmospheric temperature. The bottom layer is very hot (70°-100°C) and very salty. It collects and stores the solar energy in the form of heat energy. The middle zone is a transition zone which permits solar heat to reach bottom layer and get entrapped.- The heat energy from the pond is, then, withdrawn in the form of hot brine from the bottom zone.
It consists of a Flat-plate Solar Collector, blackened pipes and a storage tank. The water is heated, using solar energy, with applications both in domestic sector (eg. Homes, Hotels) and industries (eg. Textiles)
It can attain a temperature range of 100-300°C and can be used for domestic and community cooking purposes. It preserves nutrients in the food as cooking is slow. Also, cooking fuels can be conserved. However, initial costs are high and cooking period is more.
Solar Air Heaters
It provides dry and hot air which can be used for controlled drying, under hygienic conditions, of food grains, vegetables, fruits etc. It can also be used for space heating in cold regions and can meet process heat requirement in industries.
Solar Steam Generators
Temperatures as high as 3000°C are obtained using concentrating solar collectors like parabolic line focusing system, parabolic-point focusing system etc. The steam that can be generated is utilised for generating power.
This is a new concept in which the buildings are designed, based on climatic features, in such a way as to optimally use solar energy and reduce the dependence on commercial energy. For example, in Shimla, the houses are designed to retain solar heat, while in hot regions heat gain is minimized.
Solar Desalinization Plant
The solar energy is used to vaporize the sea water and remove the salts.