22-08-2012, 10:10 AM
ENERGY RESOURCES
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RENEWABLE AND NON-RENEWABLE ENERGY RESOURCES
Renewable resources which can be generated continuously in nature and are inexhaustible. Eg: wood, solar energy, tidal energy, hydro power, biomass energy, bio-fuels, geo-thermal energy and hydrogen.
Non-renewable resources which have accumulated in nature over a long span of time and cannot be quickly replenished when exhausted. Eg: coal, petroleum, natural gas and nuclear fuels like uranium and thorium.
RENEWABLE ENERGY RESOURCES
SOLAR ENERGY : Sun is the ultimate source of energy, directly or indirectly for all other forms of energy. The nuclear fusion reactions occurring inside the sun release enormous quantities of energy in the form of heat and light.
Solar heat collectors
Solar cells
Solar cooker
Solar water heater
Solar furnace
Solar power plant
SOLAR ENERGY
Solar heat collectors:
Can be passive/active
Passive solar heat collectors-natural materials –stones, bricks or glass materials which absorb heat during the day time and release it slowly at night.
Active solar collectors pump a heat absorbing medium(air or water) through a small collector which is normally placed on the top of the building.
2. Solar cells:
Also known as photovoltaic cells or PV cells.
Made of thin wafers of semiconductor materials like silicon and gallium.
When solar radiations fall on them, a potential difference is produced which causes flow of electrons and produces electricity.
SOLAR ENERGY
2. Solar cells:
Silicon can be obtained from silica or sand, which is abundantly available and inexpensive.
By using gallium arsenide, cadmium sulphide or boron, efficiency of the PV cells can be improved.(produces a current of 60 milli amperes)
Group of solar cells joined together in a definite pattern form a solar panel which can harness a large amount of solar energy and can produce electricity enough to run street-light, irrigation water pump.
Solar cells are widely used in calculators, electronic watches, street lighting, traffic signals, water pumps.
Also used in artificial satellites for electricity generation.
Solar cells are used for running radio and television also.
They are more in use in remote areas where conventional electricity supply is a problem.
SOLAR ENERGY
3. Solar cooker:
Make use of solar heat by reflecting the solar radiations using a mirror directly on to a glass sheet which covers the black insulated box within which the raw food is kept.
The food cooked in solar cookers is more nutritious due to slow heating.
It cannot be used at night or on cloudy days.
The direction of the cooker has to be adjusted according to the direction of the sun rays.
SOLAR ENERGY
5. Solar power plant:
Solar energy is harnessed on a large scale by using conclave reflectors which cause boiling of water to produce steam. The steam turbine drives a generator to produce electricity.
WIND ENERGY
High speed winds have a lot of energy in them as kinetic energy due to their motion. The driving force of the winds is the sun. the wind energy is harnessed by making use of wind mills.
The blades of the wind mill keep on rotating continuously due to the force of the striking mind.
The rotational motion of the blades drives a number of machines like water pumps, flour mills and electric generators.
A large number of wind mills are installed in clusters called wind farms, which feed power to the utility grid and produce a large amount of electricity.
HYDROPOWER
The water flowing in a river is collected by constructing a big dam where the water is stored and allowed to fall from a height.
The blades of the turbine located at the bottom of the dam move with the fast moving water which in turn rotate the generator and produces electricity.
Hydropower does not cause any pollution, it is renewable and normally the hydro power projects are multi-purpose projects helping in controlling floods, used for irrigation, navigation etc.
RENEWABLE ENERGY RESOURCES
TIDAL ENERGY
OCEAN THERMAL ENERGY
GEOTHERMAL ENERGY
BIOMASS ENERGY
BIO GAS
BIOFUELS
HYDROGEN
BIOFUELS
Biomass can be fermented to alcohols like ethanol and methanol which can be used as fuels.
Gasohol-common fuel used in Brazil and Zimbabwe for running cars and busses. Gasohol is a mixture of ethanol and gasoline.
Methanol is very useful since it burns at lower temperature than gasoline or diesel. Methanol too is clean, non-polluting fuel.
Methanol can be easily obtained from woody plants and ethanol from grain based or sugar containing plants.