SOLAR CELL GEOTHERMAL ENERGY ENERGY FROM THE SEA

WHAT IS A SOLAR CELL ?A solar cell is a device which directly

converts solar energy into electrical energy.

In a solar cell, it is the light energy present in solar energy which gets converted into electrical energy. So, a solar cell is also called a solar photo voltaic (SPV) cell.

The radiant heat present in solar energy doesn’t change into electrical energy.

Solar cells are usually produced from semiconductors, such as silicon.

PHOTO VOLTAIC EFFECT:

This is a phenomenon due to which light energy directly changes into electrical energy when light falls on certain light sensitive materials like silicon , gallium, etc.

STRUCTURE OF A SOLAR CELL:-

A solar cell consist of a 4cm square of a semiconductor silicon, in fact it consist of a very thin sandwich of n-type and p-type wafer of silicon in which is placed a U-shaped metal grid.

WORKING OF A SOLAR CELL:When exposed to sunlight, the solar

radiations fall on a solar cell, the n-type water produces a large number of electrons.

These electrons drift towards p-type wafer thereby generating an electric potential.

A single cell of 4cm² silicon develops a voltage of 0.5-1V and can produce about 0.7W of electricity when exposed to sun .

Presently, the best designed solar cell has a maximum efficiency of about 25% i.e. only 25% of the solar radiations falling on solar cell is converted into electricity.

SOLAR CELL PANEL:

A single cell can produce only a small amount of electricity and low voltage.

To obtain a large potential difference and more electric power, a large number of solar cell are connected in series and some in parallel. This arrangement is called a solar cell panel

The group of solar cells connected in specific pattern to produce desired potential difference or magnitude of current (electric power) is called a solar cell panel

WORKING OF SOLAR CELL PANEL: Solar cells in the solar cell are connected by wires

made up of silicon so it increases the efficiency of the solar panel.

A solar panel is mounted on a tall supporting pole or installed on a specially designed inclined roof tops so that more solar energy is incident over it.

The solar energy falling on the solar cells of the solar cell panel gets converted into electricity .

The electricity so produced flows to storage battery, where the electricity is stored in the form of chemical energy.

This charged storage battery can supply electricity whenever required.

ADVANTAGES OF SOLAR CELLS/SOLAR CELL PANEL :1. Solar cell have no moving parts, are easy to

construct, and require little maintenance.2. Solar cell panel can be installed on remote and

very less populated areas in which laying a power transmission line may be expensive and not commercially viable.

3. Solar cell and solar cell panel are renewable source of energy because both derive their energy from solar radiations, which is a renewable source of energy and also inexhaustible.

4. Solar cells and solar cell panels do not cause any environmental pollution.

5. Use of solar cells can enable us to save usage of fossil fuels as solar cells require no fuel.

DISADVANTAGES OF SOLAR CELL PANELS:

1. Expensive manufacturing: the entire process of manufacturing is expensive because of use of expensive components.

(a) Special grade silicon required for making solar cell is limited in nature. So, it is very expensive.

(b) Silver is used for interconnecting various cells in a solar cell panel is also expensive.

(c) It is costly to store electricity in a storage battery .

2. Low efficiency: the efficiency of the energy conversion is low as compared to other methods of generating electricity. The maximum efficiency of solar cell is 25% which is very low .It means it can convert only about 25% of light energy falling on them, into electricity.

3. Conversion problem: the electricity produced in the solar panel is direct current which is stored in DC (direct current) batteries. Only DC devices can be operated by DC batteries. Now most of our electric appliances operate on alternating current (AC). To operate any AC devices, we need to convert DC stored in the batteries into AC by using inverters

USE OF SOLAR PANELS: In spit of the high cost, low efficiency and conversion

problem, solar cells are used for many scientific and technological applications. Some of them are:

o Artificial satellites and probes, like mars orbits, use solar cells as the main source of energy

o Radio broadcasting or TV relay stations in remote areas use solar cell panels as for its transmission. This is because in remote areas, we may not find power transmission line as it is expensive and commercially viable.

o Traffic signals, electric watches, calculators and many toys are fitted with solar cells.

o solar cell panels are being used to produce electricity for the proposes of street lighting, operating water pumps, for domestic and agricultural works in remote/rural areas.

GEOTHERMAL

ENERGY

WHAT IS GEOTHERMAL ENERGY:The heat inside the earth that can be

utilized as a source of energy under favorable conditions is called geothermal energy.

“geo” means earth and “thermal” means heat.

Geothermal energy is the source of energy that doesn’t derive its power, directly or indirectly from the sun.

In other words, suns energy does not power the flow of geothermal energy.

IMPORTANT INFORMATION:The interior of the earth is very

hot. In the molten core lying deep inside the earth, the temperature is as high as 4000º C

Due to geological changes, molten rocks called magma formed in the deeper hot region of the earth’s core get pushed upwards and trapped in certain regions called hot spot.

These hot spots are found at some depths below the earth’s surface . It is a tremendous source of heat.

When underground water seeps down and comes in contact with the hot spot, it boils and forms steam.

The steam so formed gets compressed to very high pressure. This steam has the ability to do work.

HARNESSING OF GEOTHERMAL ENERGY:From natural geysers: At some

places, steam and hot water trapped inside layers of rocks sometimes force their way to surface through cracks in the rocks. They gush out in the form of huge fountains called geysers.

These natural sources of steam in form of natural geysers are used to turn the turbines and generate electricity.

By drilling pipes : At some places, steam trapped inside layers of rocks is brought to the earth’s surface by sinking pipes through holes drilled up to the hot spots. The steam which comes out at high pressure through holes is utilized to turn the turbines of an electric generator to produce electricity.

ADVANTAGES OF GEOTHERMAL ENERGY:Geothermal energy is a renewable source

of energy. Since the interior of the earth is going to remain hot for millions of years, geothermal energy is inexhaustible form of energy.

It is a clean source of energy as it does not cause any environmental pollution.

The cost of production of electricity is not much, i.e. the electricity produced is inexpensive and economical.

It enables us to save our fossil fuels as it requires no fuel for it production.

LIMITATIONS OF GEOTHERMAL ENERGY:  Only few sites have the potential of Geothermal

Energy.  Most of the sites, where geothermal energy is

produced, are far from markets or cities, where it needs to be consumed.

 Total generation potential of this source is too small.  There is always a danger of eruption of volcano.

 Installation cost of steam power plant is very high.  There is no guarantee that the amount of energy

which is produced will justify the capital expenditure and operations costs.

 It may release some harmful, poisonous gases that can escape through the holes drilled during construction.

ENERGY FROM

THE SEA

TIDAL ENERGY: The alternate rise and fall in the water level

of the oceans and seas is known as tides. The tides are caused due to the gravitational force pull of mainly the moon on the water and on the earth itself.

The energy obtained from the tidal waves is known as tidal.

The rise of ocean water is called high tide. The fall of ocean water is called low tide. The tides can keep very huge amount of

water in movement and therefore they provide a source of energy.

ADVANTAGES OF TIDAL ENERGY: It is an inexhaustible and renewable

source of energy. It does not cause any environmental

pollution . It is not affected due to uncertainty of

rainfall. It does not produce any harmful waste . It saves our valuable fossil fuels as it does

not require any fuel for its production.Once the tidal power plant is established,

it has low maintenance cost.

LIMITATIONS OF TIDAL WAVE ENERGY: Limited scope: Tidal dams cannot be established

everywhere. There are very few sites around the world which is suitable for building tidal dams to harness tidal energy.

Small scale power generation: The rise and fall of sea water during tides is not enough to generate electricity on a large scale.

High maintenance cost: The sluice gates and blades of the turbines are exposed to salty sea-water, so they need a high level of maintenance , so the cost incurred in its maintenance is high.

Valuable output: There is variation in the tides during the daytime so the power generation is also affected .

SEA-WAVE ENERGY: The energy associated with the sea

waves is known as sea wave energy. The waves are generated by the

strong winds blowing across the sea. It actually happens when the strong winds travel across the sea, the surface of the sea causing waves.

These fast moving huge waves have a lot of kinetic energy in them.

The kinetic energy possessed by the huge waves near the sea-shore can be trapped to generate electricity.

DEVICES TO TRAP WAVE ENERGY FOR GENERATING ELECTRICITY:

Oscillating water column

Wave capture devices

Wave profile devices

These are the three main devices to trap energy for generating electricity.

Wave capture device

ADVANTAGES OF WAVE ENERGY:No costs for energyNo waste productsSignificant amount of energy can

be producedLow running costHelp to reduce reliance on non

renewable resources.

DISADVANTAGES OF WAVE ENERGY: Variable energy supply Suitable location, where strong wave occurs

required Could be noisy Equipment should be strong to stand against

rough weather High initial capital costs Visual effect it near land, this could affect

tourism as well Can harm the marine ecosystem More expensive for the average consumer

compared to energy generated from non renewable resources.

OCEAN THERMAL ENERGY:

The energy available due to the difference in the temperature between the water at the surface and water at depths is called ocean thermal energy(OTE)

WORKING OF THERMAL ENERGY POWER PLANT: It can be operational when the temperature

difference between the water at the surface and water at depths up to 2km is 20ºC or more . The warm water of the sea is used to boil a liquid like ammonia or a chlorofluorocarbon (CFC) in the evaporator of OTEC plant to obtain its vapor.

The resulting vapors of the ammonia liquid are used to rotate the blades of the turbines. The rotating turbine rotates the armature of the generate electricity. The cold water from the depth of the ocean is pumped up to the condenser of the OTEC power plant. This cold water is used to condense ammonia vapor into liquid ammonia. The liquid ammonia is again taken back to the evaporator and the process is repeated again and again.

ADVANTAGES OF OTEC:It is same as tidal energy and wave energy, i.e. it is an inexhaustible and renewable source of energy, doe not cause any harmful waste product, saves valuable fossil fuels and has low maintenance cost.

DISADVANTAGES OF OTEC:

It is same as tidal energy and wave energy, i.e. it involves investment, produces electricity in small scale, high maintenance cost and high cost of electricity production.

GROUP MEMBERS:

HANIYA HEDAYTH MALAVIKA RAJESHKUMAR SUMBAL BAHADUR SALMA DAULAT FATHIMA IRSHANA