A project report on solar energy. This project report will help you to learn about: 1. Introduction to Solar Energy 2. Advantages of Solar Energy 3. Disadvantages of Solar Energy 4. Applications of Solar Energy 5. Environmental Implications of Solar Energy.
Contents:
- Project Report on Introduction to Solar Energy
- Project Report on the Advantages of Solar Energy
- Project Report on the Disadvantages of Solar Energy
- Project Report on the Applications of Solar Energy
- Project Report on the Environmental Implications of Solar Energy
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Project Report # 1. Introduction to Solar Energy:
Energy produced and radiated by sun is known as solar energy. This solar energy can be converted directly or indirectly into other forms of energy such as heat and electricity.
Now it has been proved that the solar energy can be stored by either of these methods:
i. By producing hydrogen and storing it.
ii. By storing it in mechanical or electrical devices.
iii. By storing it in containers of chemicals called eutectic or phase changing salts.
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Most of the energy is received from the Sun in the form of short wave radiations of light. When this radiation strikes a solid or liquid, it gets absorbed and transformed into heat energy. This heat energy is either stored (warming the material) or is conducted to the surrounding materials (air, water etc.) or is re-radiated (in the form of a long wave radiation) to the other material having relatively lower temperature.
Glass possess very little interference to the incoming solar energy i.e. it easily transmits short wave radiation whereas it is a very poor transmitter of long wave radiation i.e. once the solar energy has passed through the glass and has been absorbed by some material (black painted surface) inner to it, then the heat will not be re-radiated back, out of the glass (thus glass acts as a heat trap).
This is the physical principle for the conversion of solar energy into heat energy.
Project Report # 2. Advantages of Solar Energy:
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i. It is a renewable source of energy.
ii. It is available at all parts of the world.
iii. It is free source of energy.
iv. It is non-polluting source of energy.
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Project Report # 3. Disadvantages of Solar Energy:
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i. It is intermittent in nature
ii. Variable in nature.
iii. It requires large area for collection and storage.
India receives 5000 Trillian kW/h of sum in a year.
India receives abundant sunshine with about 1648-2108 kWh/m2/yr. with nearly 250- 300 days of useful sun shine in a year. The daily solar energy incidence is between 4 to 7 kWhr/m2. Solar energy received in the form of radiation can be converted to other forms of energy such as heat and electricity. Energy radiated by the sun as electromagnetic waves, (wavelength 0.2 to 0.4 micrometers)
Due to absorption and scattering in the atmosphere the maximum flux density is 1 kW/sqm 45% energy in the form of visible rays and 44% as infra-red radiation. The enormous solar energy resource may be converted in to other forms of energy through thermal photovoltaic conversion routes. The solar thermal route uses radiation in the form of heat in turn may be converted to mechanical, electrical on chemical energy.
Sun gives us 1000 times more power then we need and if only a small amount of this form of energy could be used, it will be one of the most important supplies of energy. Received in the form of radiation, solar energy can be converted directly or indirectly into other forms of energy (heat and electricity) which can be utilised by man.
It is the solar energy which is responsible for:
i. Keeping the temperature of the earth above the temperature in colder space.
ii. Causing currents in the atmosphere and oceans.
iii. Causing the water cycle.
iv. Occurrence of photosynthesis in plants.
The sun is an inexhaustible source of useful energy but it has a few drawbacks namely:
i. Uncertainty of availability of solar energy due to clouds, wind, haze etc.
ii. Large spaces required for the collection of solar energy at a useful rate.
In India sunlight is abundant for a major part of the year and so the utilisation of solar energy is of great significance to India. Earlier, the utilisation of solar energy was limited owing to two drawbacks-firstly was the fact that solar energy was believed to be incapable of storage and secondly it was considered to be a dilute form of energy.
Project Report # 4. Applications of Solar Energy:
i. Solar Water Heating:
A solar water heating unit comprises a blackened flat plate metal collector with an associated metal tubing facing the general direction of the sun. The plate collector has a transparent glass cover above and a layer of thermal insulation beneath it.
The metal tubing of the collector is connected by a pipe to an insulated tank that stores hot water during cloudy days. The collector absorbs solar radiations and transfers the heat to the water circulating through tubing either by gravity or by a pump.
This hot water is supplied to the storage tank via the associated metal tubing. This system of water heating is commonly used in hotels, guest houses, tourist bungalows, hospitals, canteens as well as domestic and industrial units.
ii. Solar Heating of Buildings:
Solar energy can be used for space heating of buildings in many ways namely:
(a) Collecting the solar radiation by some element of the building itself i.e. solar energy is admitted directly into the building through large South-facing windows.
(b) Using separate solar collectors which may heat either water or air or storage devices which can accumulate the collected solar energy for use at night and during inclement days.
When the building requires heat then from these collectors or storage devices, the heat is transferred by conventional equipment such as fans, ducts, air outlets, radiators and hot air registers etc. to warm up the living spaces of a building.
When the building does not require heat, the heated air or water from the collector can be moved to the heat storage device such as well insulated water tank or other heat holding material. For inclement days, an auxiliary heating system using gas, oil or electricity is required as a back-up system.
iii. Solar-distillation:
In arid, semi-arid or coastal areas there is scarcity of potable water. The abundant sunlight in these areas can be used for converting saline water into potable distilled water by the method of solar distillation.
In this method, solar radiation is admitted through a transparent air tight glass cover into a shallow blackened basin containing saline water. Solar radiation passes through the covers and is absorbed and converted into heat in the blackened surface causing the water to evaporate from the brine (impure saline water). The vapours produced get condensed to from purified water in the cool interior of the roof.
The condensed water flows down the sloping roof and is collected in the troughs placed at the bottom and from there into a water storage tank to supply potable distilled water in areas of scarcity, in colleges, school science laboratories, defence labs, petrol pumps, hospitals and pharmaceutical industries.
Per litre distilled water cost obtained by this system is cheaper than distilled water obtained by other electrical energy-based processes.
iv. Solar Furnaces:
In a Solar furnace, high temperature is obtained by concentrating the solar radiations onto a specimen using a number of heliostats (turnable mirrors) arranged on a sloping surface. The solar furnace is used for studying the properties of ceramics at extremely high temperatures above the range measurable in laboratories with flames and electric currents.
Heating can be accomplished without any contamination and temperature can be easily controlled by changing the position of the material in focus. This is especially useful for metallurgical and chemical operations. Various property measurements arc possible on an open specimen. An important future application of solar furnaces is the production of nitric acid and fertilisers from air.
v. Solar Cooking:
A variety of fuel like coal, kerosene, cooking gas, firewood dung cakes and agricultural wastes are used for cooking purposes. Due to the energy crisis, supply to these fuels are either deteriorating (wood, coal, kerosene, cooking gas) or are too precious to be wasted for cooking purposes (cow dung can be better used as manure for improving soil fertility).
This associated the used of solar energy for cooking purposes and the development of solar cookers.
A simple solar cooker is the flat plate box type solar cooker. It consists of a well-insulated metal or wooden box which is blackened from the inner side. The solar radiations entering the box are of short wavelength. As higher wavelength radiations are unable to pass through the glass covers, the re-radiations from the blackened interior to outside the box through the two glass covers is minimised, thereby minimising the heat loss.
The heat loss due to convection is minimised by making the box airtight. This is achieved by providing a rubber strip between the upper lid and the box for minimising the heat loss due to conduction, the space between the blackened tray and outer cover of the box is filled with an insulating material like glass-wool, saw-dust, paddy husk etc.
When placed in sunlight, the solar rays penetrate the glass cover and are absorbed by the blackened surface thereby resulting in an increase in temperature inside the box. Cooking pots blackened from outside are placed in the solar box.
The uncooked food gets cooked with the heat energy produced due to increased temperature of the solar box. Collector area of such a solar cooker can be increased by providing a plane reflector mirror. When this reflector is adjusted to reflect the sun rays into the box, then a 15°C to 25°C rise in temperature is achieved inside the cooker box.
The solar cooker requires neither fuel nor attention while cooking food and there is no pollution, no charring or over flowing of food and the most important advantage is that nutritional value of the cooked food is very high as the vitamins and natural tastes of the food are not destroyed.
Maintenance cost of the solar cooker is negligible. The main disadvantage of the solar cooker is that the food cannot be cooked at night, during cloudy days or at short notice. Cooking takes comparatively more time and chapattis cannot be cooked in a solar cooker.
vi. Solar Electric Power Generation (Photo voltaic system):
Electric energy or electricity can be produced directly from solar energy by means of photovoltaic cells. The photovoltaic cell is an energy conversion device which is used to convert photons sunlight directly into electricity. It is made of semiconductors which absorb the photons received from the sun, creating free electrons with high energies.
These high energy free electrons are induced by an electric field, to flow out of the semiconductor to do useful work. This electric field in photo voltaic cells is usually provided by a p-n junction of materials which have different electrical properties.
There are different fabrication techniques to enable these cells to achieve maximum efficiency. These cells are arranged in parallel or series combination to form cell modules. Some of the special features of these modules are high reliability, no expenditure on fuel, minimum cost of maintenance, long life, portability, modularity, pollution free working etc.
Application of photovoltaic cells have been used to operate:
a. Irrigation pumps,
b. Rail road crossing warnings,
c. Navigational signals,
d. Highway emergency call systems,
e. Automatic meteorological station etc. in areas where it is difficult to lay power lines,
f. They are also used for weather monitoring and
g. Portable power sources for televisions, calculators, watches, computer card readers, battery charging and in satellites etc.
Besides these, photovoltaic cells are used for the emergisation of pump sets for irrigation, drinking water supply and for providing electricity in rural areas i.e. street lights etc.
The photovoltaic conversion systems convert solar radiation directly into electricity through silicon solar cells. These may be single crystal silicon cell, polycrystalline cells, amorphic solar cells etc. such systems are used for community lighting, radio and TV sets, light houses, offshore platforms and installation in remote areas.
An important application of these systems is pumping of water for micro-irrigation and drinking purposes. Such systems are decentralised on the spot electricity generation systems and help to replace diesel utilizing systems.
They may be installed in remote areas as forests, deserts etc. under the National Solar Photovoltaic Energy Demonstration Programme (NSPEDP) the DNES has since 1980 installed a number of photovoltaic devices with a target of producing 1 MW of electricity. Such systems are used for pumping water, village electrification, use in TV sets etc. In rural areas photovoltaic can be used as a biomass based system.
The solar thermal system utilizes radiation in the form of heat which can be converted in to mechanical, electrical or chemical energy. The sun rays are used to supersede a fluid that is then used to drive an electricity generating turbine.
Most Indian roof tops can be fitted with Photovoltaic solar modules the modules will be loaded with solar energy during the day time which will directly convert it in to directly stored in a battery. In the night you concerns time of meter and even send the excess amount to the grid of a premium.
vii. Solar Thermal Power Production:
Solar thermal power production means the conversion of solar energy into electricity through thermal energy. In this procedure, solar energy is first utilised to heat up a working fluid, gas, water or any other volatile liquid. This heat energy is then converted into mechanical energy in a turbine. Finally a conventional generator coupled to a turbine converts this mechanical energy into electrical energy.
viii. Production of Power through Solar Ponds:
A solar pond is a natural or artificial body of water utilised for collecting and absorbing solar radiation and storing it as heat. It is very shallow (5-10 Cm deep) and has a radiation absorbing (black plastic) bottom.
It has a curved fibre glass cover over it to permit the entry of solar radiation but reduces losses by radiation and convection (air movement). Loss of heat to the ground is minimised by providing a bed of insulating material under the pond.
Solar ponds utilise water for collecting and storing the solar energy which is used for many applications such as space heating, industrial process heating and to generate electricity by driving a turbine powered by evaporating an organic fluid with a low boiling point.
ix. Solar Green Houses:
A green house is a structure covered with transparent material (glass or plastic) that acts as a solar collector and utilizes solar radiant energy to grow plants. It has heating, cooling and ventilating devices for controlling the temperature inside the green house.
Solar radiations can pass through the green house glazing but the thermal radiations emitted by the objects within the green house cannot escape through the glazed surface. As a result, the radiations get trapped within the green house and result in an increase in temperature.
As the green house structure has a closed boundary, the air inside the greenhouse gets enriched with CO2 as there is no mixing of the green house air with the ambient air. Further, there is reduced moisture loss due to restricted transpiration. All these features help to sustain plant growth throughout the day as well as during the night and all year round.
In-spite of the intermittent and variable manner in which solar energy arrives at the earth’s surface, and the large area required to collect the energy at a useful rate, solar energy is regarded as an inexhaustible source of useful, non-polluting energy.
Project Report # 5. Environmental Implications of Solar Energy:
The use of solar energy, from the environmental view point, is a completely benign operation. In case of solar thermal route, apart from land use, there exist absolutely no environmental consequences of producing energy from these sources.
i. However, the sites for larger installations of solar power plants should be selected without reducing the forest cover.
ii. Cadmium used in fabricating thin film solar cells, is both poisonous and a possible carcinogen. Since only small quantities of cadmium are released from discarded PV panels, the dangers involved are not so serious.
iii. Carbon dioxide produced while forming silicon from silica may increase the atmospheric temperature causing green-house effect.
iv. Silicon dust is also an important occupational hazard.