The document discusses solar energy as an ultimate renewable resource. It describes how solar energy originates from thermonuclear fusion in the sun and can be harnessed in various ways. Specifically, it discusses using solar energy to heat water through passive and active systems, using it to heat living spaces through proper insulation and thermal mass materials, and directly converting it to electricity through photovoltaic cells. While intermittent availability is a disadvantage, solar energy is pollution-free and sustainable.

1. Solar Energy:Solar Energy:
The UltimateThe Ultimate
Renewable ResourceRenewable Resource
BY-SOUMYABRATA
BASAK

2. contentscontents
 What is solar energy?What is solar energy?
 How much solar energy?How much solar energy?
 Putting solar energy to usePutting solar energy to use
 Heating waterHeating water
 Heating living spacesHeating living spaces
 Direct conversion into electricityDirect conversion into electricity
 Advantages & DisadvantagesAdvantages & Disadvantages
 Final thoughtsFinal thoughts
 ReferencesReferences

3. What is Solar Energy?What is Solar Energy?
 Originates with theOriginates with the
thermonuclearthermonuclear
fusion reactionsfusion reactions
occurring in theoccurring in the
sun.sun.
 Represents theRepresents the
entireentire
electromagneticelectromagnetic
radiation (visibleradiation (visible
light, infrared,light, infrared,
ultraviolet, x-rays,ultraviolet, x-rays,
and radio waves).and radio waves).

4. How much solar energy?How much solar energy?
The surface receives about 47% of the total solar
energy that reaches the Earth. Only this amount is
usable.

5. Putting Solar Energy to Use:Putting Solar Energy to Use:
Heating WaterHeating Water
 Two methods of heatingTwo methods of heating
water: passive (no movingwater: passive (no moving
parts) and active (pumps).parts) and active (pumps).
 In both, a flat-plateIn both, a flat-plate
collector is used to absorbcollector is used to absorb
the sun’s energy to heatthe sun’s energy to heat
the water.the water.
 The water circulatesThe water circulates
throughout the closedthroughout the closed
system due to convectionsystem due to convection
currents.currents.
 Tanks of hot water areTanks of hot water are
used as storage.used as storage.

6. Heating Water: ActiveHeating Water: Active
SystemSystem
Active System uses antifreeze so that the liquid does not
freeze if outside temp. drops below freezing.

7. Heating Water—Last ThoughtsHeating Water—Last Thoughts
 Efficiency of solar heating system is always less than 100%Efficiency of solar heating system is always less than 100%
because:because:
 % transmitted depends on angle of incidence,% transmitted depends on angle of incidence,
 Number of glass sheets (single glass sheetNumber of glass sheets (single glass sheet
transmits 90-95%), andtransmits 90-95%), and
 Composition of the glassComposition of the glass
 Solar water heating saves approx. 1000 megawatts ofSolar water heating saves approx. 1000 megawatts of
energy a yr, equivalent to eliminating the emissions fromenergy a yr, equivalent to eliminating the emissions from
two medium sized coal burning power plants.two medium sized coal burning power plants.
 By using solar water heating over gas water heater, aBy using solar water heating over gas water heater, a
family will save 1200 pounds of pollution each year.family will save 1200 pounds of pollution each year.
 Market for flat plate collectors grew in 1980s because ofMarket for flat plate collectors grew in 1980s because of
increasing fossil fuels prices and federal tax credits. Butincreasing fossil fuels prices and federal tax credits. But
by 1985, when these credits were removed and fossil fuelby 1985, when these credits were removed and fossil fuel
prices were low, the demand for flat plate collectorsprices were low, the demand for flat plate collectors
shrunk quickly.shrunk quickly.
 While solar water heating is relatively low in the US, inWhile solar water heating is relatively low in the US, in
other parts of the world such as Cyprus (90%) and Israelother parts of the world such as Cyprus (90%) and Israel
(65%), it proves to be the predominate form of water(65%), it proves to be the predominate form of water
heating.heating.

8. Heating Living SpacesHeating Living Spaces
 Best design of a building is for it to act as aBest design of a building is for it to act as a
solar collector and storage unit. This issolar collector and storage unit. This is
achieved through three elements: insulation,achieved through three elements: insulation,
collection, and storage.collection, and storage.
 Efficient heating starts with proper insulationEfficient heating starts with proper insulation
on external walls, roof, and the floors. Theon external walls, roof, and the floors. The
doors, windows, and vents must be designed todoors, windows, and vents must be designed to
minimize heat loss.minimize heat loss.
 Collection: south-facing windows andCollection: south-facing windows and
appropriate landscaping.appropriate landscaping.
 Storage: Thermal mass—holds heat.Storage: Thermal mass—holds heat.
 Water= 62 BTU per cubic foot per degreeWater= 62 BTU per cubic foot per degree
F.F.
 Iron=54, Wood (oak) =29, Brick=25,Iron=54, Wood (oak) =29, Brick=25,
concrete=22, and loose stone=20concrete=22, and loose stone=20

9. Heating Living SpacesHeating Living Spaces
Passive Solar
Trombe Wall
Passively heated
home in Colorado

10. Direct Conversion intoDirect Conversion into
ElectricityElectricity
 Photovoltaic cells arePhotovoltaic cells are
capable of directlycapable of directly
converting sunlightconverting sunlight
into electricity.into electricity.
 A simple wafer ofA simple wafer of
silicon with wiressilicon with wires
attached to the layers.attached to the layers.
Current is producedCurrent is produced
based on types ofbased on types of
silicon (n- and p-types)silicon (n- and p-types)
used for the layers.used for the layers.
Each cell=0.5 volts.Each cell=0.5 volts.
 Battery needed asBattery needed as
storagestorage
 No moving partsNo moving partsdodo
no wear out, butno wear out, but
because they arebecause they are
exposed to the weather,exposed to the weather,
their lifespan is abouttheir lifespan is about
20 years.20 years.

11. Solar Panels inSolar Panels in
UseUse
 Because of their currentBecause of their current
costs, only rural and othercosts, only rural and other
customers far away fromcustomers far away from
power lines use solar panelspower lines use solar panels
because it is more costbecause it is more cost
effective than extendingeffective than extending
power lines.power lines.
 Note that utility companiesNote that utility companies
are already purchasing,are already purchasing,
installing, and maintaininginstalling, and maintaining
PV-home systems (IdahoPV-home systems (Idaho
Power Co.).Power Co.).
 Largest solar plant in US,Largest solar plant in US,
sponsored by the DOE,sponsored by the DOE,
served the Sacramento area,served the Sacramento area,
producing 2195 MWh ofproducing 2195 MWh of
electric energy, making itelectric energy, making it
cost competitive with fossilcost competitive with fossil
fuel plants.fuel plants.

12. ADVANTAGES & DISADVANTAGESADVANTAGES & DISADVANTAGES
 AdvantagesAdvantages
 All chemical and radioactive pollutingAll chemical and radioactive polluting
byproducts of the thermonuclear reactionsbyproducts of the thermonuclear reactions
remain behind on the sun, while only pureremain behind on the sun, while only pure
radiant energy reaches the Earth.radiant energy reaches the Earth.
 Energy reaching the earth is incredible. ByEnergy reaching the earth is incredible. By
one calculation, 30 days of sunshine strikingone calculation, 30 days of sunshine striking
the Earth have the energy equivalent of thethe Earth have the energy equivalent of the
total of all the planet’s fossil fuels, both usedtotal of all the planet’s fossil fuels, both used
and unused!and unused!
 DisadvantagesDisadvantages
 Sun does not shine consistently.Sun does not shine consistently.
 Solar energy is a diffuse source. To harness it,Solar energy is a diffuse source. To harness it,
we must concentrate it into an amount andwe must concentrate it into an amount and
form that we can use, such as heat andform that we can use, such as heat and
electricity.electricity.
 Addressed by approaching the problemAddressed by approaching the problem
through:through:
1) collection, 2) conversion, 3) storage1) collection, 2) conversion, 3) storage

13. Final ThoughtFinal Thought
 Argument that sun provides power onlyArgument that sun provides power only
during the day is countered by the fact thatduring the day is countered by the fact that
70% of energy demand is during daytime70% of energy demand is during daytime
hours. At night, traditional methods can behours. At night, traditional methods can be
used to generate the electricity.used to generate the electricity.
 Goal is to decrease our dependence on fossilGoal is to decrease our dependence on fossil
fuels.fuels.
 Currently, 75% of our electrical power isCurrently, 75% of our electrical power is
generated by coal-burning and nucleargenerated by coal-burning and nuclear
power plants.power plants.
 Mitigates the effects of acid rain, carbonMitigates the effects of acid rain, carbon
dioxide, and other impacts of burning coaldioxide, and other impacts of burning coal
and counters risks associated with nuclearand counters risks associated with nuclear
energy.energy.
 pollution free, indefinitely sustainable.pollution free, indefinitely sustainable.

14. ReferencesReferences
 www.google.comwww.google.com
 Power plant engineering-P.k.NagPower plant engineering-P.k.Nag
 Environmental engineering-A.k.DeyEnvironmental engineering-A.k.Dey
 http://en.wikipedia.org/wiki/solar-energyhttp://en.wikipedia.org/wiki/solar-energy
 http://www.geocities.com/nastywik/nonconvehttp://www.geocities.com/nastywik/nonconve
 Class NoteClass Note

15. The EndThe End