Utilization of solar energy requires COLLECTORS for initial collection of energy
FLAT PLATE COLLECTORS
Incident solar rays are absorbed by the FLAT PLATE of the collector.
This energy is utilized for various applications
Widely used; preferred for LOW TEMP applications such as
COOKING, WATER HEATING, DRYING OF FOODGRAINS AND
VEGETABLES, HEATING AND COOLING OF BUILDINGS, etc
*absorber plate- metal; black coating to absorb rays
*transparent cover-glass; reflects incident solar energy back to the absorber plate
*water tubes-metallic; cold water circulates; attached to the
absorber plate; cold water gets heated up- can be used
*Thermal insulation-below the absorber
plate;to prevent heat loss by conduction
COMPONENTS
FOCUSING TYPE COLLECTORS
Solar rays fall on LARGE, CURVED , REFLECTING SURFACE
which reflects all incident rays and focusses them to form a highly
concentrated narrow beam which is absorbed later.
Used for HIGH TEMP heating applications for INDUSTRIAL PURPOSES
ADVANTAGES AND DISADVANTAGES
ADVANTAGES
Inexhaustible; Most abundant
Environmentally clean source
freely available-hence can be used as
alternative to high cost energy sources
can be converted to other forms-wide range of applications
DISADVANTAGES
dilute source of energy
availibility varies with time and weather
day energy has to be STORED for the night-
need for storage increases the cost
collection of solar energy and it's
concentration requires special components
HYDEL
DAM is built to collect (rain) water in a reservoir;
GRAVITATIONAL POT'L ENERGY is stored in water above the
dam; water from dam flows through PENSTOCK and enters
NOZZLE where POTENTIAL energy is converted to KINETIC
energy. Kinetic energy is used to run the TURBINE which drives
the GENERATOR to produce ELECTRICITY
ADVANTAGES AND DISADVANTAGES
ADVANTAGES
After building of dam, energy is virtually FREE
working COST of system is LESS
electricity can be generated CONSTANTLY
NO WASTE or POLLUTION
DISADVANTAGES
Dependent on QUANTITY of water available
construction of DAM is EXPENSIVE
finding a suitable SITE for power plant is difficult
WIND
It is the KINETIC energy of large masses of AIR moving over the earth's
surface. Can be harnessed using WIND MILLS or WIND TURBINES
WIND MILL:
*blades: specially designed; connected to shaft; designed large- to
extract largest possible volume of air.BLADES rotate due to kinetic
energy of flow of wind(which in turn make the shaft rotate; drives
generator to produce electricity)
*shaft- connected to small generator fixed in axis of wind mill
also used to PUMP
UNDERGROUND WATER
for drinking and irrigation
ADVANTAGES AND DISADVANTAGES
ADVANTAGES
inexhaustible
freely available; environment friendly
cheap source for power generation
freely available- hence can be
used as alternate power source
good method for supplying energy to REMOTE areas
DISADVANTAGES
wind is NOT always PREDICTABLE
wind mills cannot be located at ALL places
GEOTHERMAL
It is the HEAT energy stored deep inside the earth.
HARNESSING geothermal energy
GT energy-found in form of heat
content of DRY ROCKS. HOT ZONES
deep inside the earth are identified
and this heat energy is TAPPED by
DRILLING DEEP HOLES inside the
earth
COLD water is FORCED THROUGH in one of the BORE
HOLES; due to heat of the rocks, water converts to STEAM;
This HIGH PRESSURE-HIGH TEMP steam is drawn using
another BORE HOLE. Steam is passed through
SEPARARATOR to remove sediments/impurities collected.
PURIFIED STEAM-passed through SUPERHEATOR or
directly to TURBINE-electricity is generated
After doing WORK, steam is passed to CONDENSER and the cycle repeats.
ADVANTAGES AND DISADVANTAGES
ADVANTAGES
free from POLLUTION
AFTER building GT station, power is free
can also be used to WARM HOUSES
apart from power generation
DISADVANTAGES
SITE LOCATION for GT plant is difficult
Difficult to DRILL DEEP BORE HOLES
Hazardous GASES and MINERALS may come up from
underground; difficult to safely dispose off.
TIDAL
During HIGH TIDE period, water flows from sea to tidal basin
through WATER TURBINES since water level in sea is more).
This operates the turbine and ultimately the GENERATOR.
During LOW TIDE period, water flows from TIDAL BASIN to sea.
Here, FLOWING WATER drives the turbine to generate power.
ADVANTAGES AND DISADVANTAGES
ADVANTAGES
pollution free
after DAM building, power is FREE
Tides are PREDICTABLE.
DISADVANTAGES
HIGH capital investment
provides power for only about 10
HOURS/DAY when tide is actually moving
very few SUITABLE SITES
OCEAN THERMAL ENERGY
CONVERSION
Oceans absorb most of the solar radiation incident and thus it's surface has thermal energy
As long as the temp differs by about 20C(36F), OTEC can produce significant amount of power
HARNESSING:
EQUIPMENT: Turbine-generator mounted on a
floating platform, evaporator, condenser, pump
Warm water from Ocean surface is drawn into EVAPORATOR in
which LIQUID AMMONIA absorbs heat from the water. NH3
vapourizes and this HIGH PRESSURE AMMONIA flows from
evaporator through turbine where it EXPANDS and runs the turbine.
By coupling the turbine to the GENERATOR, power can be generated.
After doing work, LOW PRESSURE AMMONIA passes through
CONDENSER where it is condensed to liq. NH3 by giving away the
heat to the cold water drawn from the deep of the ocean. Liq. NH3 is
pumped back to the evaporator and the cycle repeats
ADVANTAGES AND DISADVANTAGES
ADVANTAGES
renewable
can be used on LARGE SCALE
pollution free
exploits NATURAL TEMP GRADIENT in ocean.
DISADVANTAGES
High CAPITAL cost
Enormous ENGG EFFORTS
BIOMASS
The waste wood, tree branches,cow dung and other materials are fed into a furnace where it is burnt. The heat is transferred to water from which steam is generated