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RENEWABLE ENERGY
SOURCES
SOLAR ENERGY
Readily available and cheapest
 Non polluting
 Finding appropriate means for efficient
utilisation of solar energy will reduce the use of
non renewable energy source which will make the
environment cleaner
 Output of sun–2.8x1023 kW
 Energy reaching the earth-1.5x1018KWh/year
 Insolation-The amount of incident solar power on
a unit surface (KW/m2)
 Solar constant-1.37kW/m2
 50% solar energy is in the form of thermal energy

SOLAR ENERGY UTILISATION
Direct solar power
 It involves only one step transformation into
usable form
eg: Sunlight hits photovoltaic cell generating
electricity
Sunlight directly converted into heat energy
Indirect solar power
 It involves more than one transformation to
reach a usable form
Eg: vegetation uses photosynthesis to convert solar
energy to chemical energy, which can later be
burnt as fuel to generate electricity
ADVANTAGES
Pollution free, sustainable energy source
 Facilities can operate with little maintenance
after initial setup
 Becoming economical
 Solar power can be viewed as a local resource
because of regional climatic variance

DISADVANTAGE
Practical in areas of favourable climate
 Not available at night, reduced during cloud
cover
 It must be converted into some other forms of
energy to be stored
 Produces DC which must be converted into AC
power

WIND ENERGY
Wind is a by-product of solar energy (2% of sun’s
energy reaching earth)
 During the day, the air above the land heats up
more quickly than the air over water.
 The warm air over the land expands and rises,
and the heavier, cooler air rushes into take its
place, creating winds.
 Wind is used to turn the turbines
 Wind turbines classified into two types:
(a)horizontal axis and (b) vertical axis

WIND POWER
ADVANTAGES
It is a renewable energy, cleanest energy
 Wider adoption can reduce the dependence on
fossil fuel
 Less air and water pollution as it does not release
toxic gases or destroy environment
 Initial cost: cost of production is coming down
steadily
 Creates more job: job opportunities of installation
and maintenance

DISADVANTAGES
Higher initial investment
 Good wind sites are often located in remote areas
 Wind resource development may not be the most
profitable use of the land
 Turbines may cause noise and sound pollution
 The turbine blades may damage local wild life

HYDROELECTRIC POWER
Generated by the flow of water through turbine
 Generator shaft turns, which generates
electricity
 Components of hydel power
1. Dam/reservoir/large buffer tank
2. Penstock
3. Power house: Turbines, generators and
step-up transformers
 Hydel power plants: large, small, Mini, Micro etc

TIDAL POWER
Tidal energy is the energy due to the water
waves created in the ocean.
 Tidal energy is also called hydropower –Mainly
due to rising and falling of waves
 The raising and falling waves are used to rotate
the turbines
 Rising and falling is due to gravitational forces of
sun and moon, and also due to rotation of earth

ADVANTAGES
Renewable energy, cleanest source
 Not expensive to operate and maintain compared
to other
 Low noise pollution as any sound generated is
transmitted through water
 High predictability as high tide and low tide can
be predicted in advance
 Low visual impact as the tidal turbines are
submerged beneath the water

DISADVANTAGES
Not always a constant source of energy as it
depends on the strength and flow of tides
 Requires suitable site, where tides are strong
 Must be able to withstand forces of nature
resulting in high capital, construction and
maintenance costs
 May damage the fish and marine ecosystem
 Intermittent power generation

GEOTHERMAL ENERGY
Steam and hot water produced inside the earth is
used to heat buildings or generate electricity
 Below the crust of the earth, the top layer of the
mantle is a hot liquid rock called magma.
 Crust of earth floats on this liquid magma
mantle.
 Water close to the hot rock (>10,000 feet from
ground) can reach temperatures of more than
148°C.

STRUCTURE OF EARTH
TEMPERATURE VARIATION
GEOTHERMAL POWER PLANTS
GEOTHERMAL ENERGY
ADVANTAGES
renewable source of energy
 Non polluting and environmental friendly
 No waste generation or by-product
 Geothermal energy can be used directly
 Maintenance cost is comparatively low
 Geothermal power plants don’t occupy too much
space and thus help in protecting natural
environment
 Unlike solar energy, it is not dependent on
weather conditions

DISADVANTAGES
Most geothermal sites are in remote areas
 Total generation potential is low
 There is always a danger 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 operation cost
 It may release some harmful, poisonous gases
that can escape through holes drilled during
construction
