Renewable and Non-renewable sources of energy

1. Energy Sources
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2. Sources of Energy
Renewable sources Non-renewable sources
The resources that can be renewed or
replaced are called renewable
sources of energy.
The resources that cannot be
renewed once they are consumed are
called nonrenewable sources of
energy.
These resources do not cause any
pollution to the environment.
These resources cause pollution to
the environment.
Renewable resources are
inexhaustible.
Non- Renewable resources are
exhaustible.
Renewable resources are not affected
by the human activities.
Non- Renewable resources are
affected by the human activities.
Examples of Renewable resources-
Air, water and solar energy
Examples of Renewable resources-
Mineral, oil and Coal
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3. Alternative Sources of Energy
 Alternative energy sources include those that do not
consume fossil fuels. These are widely available and do
not cause any undesirable consequences to the
environment.
 Here is the list of major alternative energy sources.
• Solar Energy
• Wind Energy
• Biomass Energy
• Geothermal Energy
• Tidal Energy
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4. Geothermal Energy
• Geothermal energy is the thermal energy generated
and stored inside the Earth’s crust.
• The centre of the Earth is very hot which melts the rocks,
increases by 80 C where volcano and earthquake are active
• The molten rocks formed in the Earth’s crust are pushed
upward where they get trapped in certain regions called ‘hot
spots’. When underground water comes in contact with the
hot spot, steam is generated.
• Sometimes this hot water formed region finds outlets at the
surface. When this hot water gushes out of one of these
outlets, it is called hot springs.
• Heat is evolved out during the volcanic eruption and
earthquakesAnjan Nepal

5. Geothermal energy
• Below Earth’s surface, very
high heat melts rock to form
magma. This heat is called
geothermal energy.
• In some places, the magma
is close to the surface. Here,
underground water boils
and forms steam.
• Geothermal energy can also
be used to generate
electricity. Steam turns
generators in a power plant
to produce electricity.
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6. Geothermal Energy
Advantages
• Renewable resource: Geothermal energy is free and abundant
• Green energy: Geothermal energy is non-polluting and
environment-friendly
• Can be used directly: for melting of ice on the roads, heating
houses in winters, greenhouses, public baths, etc.
Disadvantages
• High installation
• Intensive research required
• Limited to particular regions
• Impact to the environment: may result in the release of highly
toxic gases into the environmentAnjan Nepal

7. Tidal Energy
• The energy obtained from the rise and fall of
tides is called the tidal energy.
• Tidal barrages or dams are constructed across
a narrow opening to the sea. Water rushes
into the dam when the sea level rises. This
moves the blades of the turbines which are
attached at the opening of the dam. This
results in the generation of electricity.
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8. Tidal Energy
Advantages
• Environment-friendly: No pollution
• High energy production
• Inexhaustible source of energy
Limitations
• High tidal power plant construction costs
• Disrupts in navigation system
• Location limits: Not useful for landlocked countries like
Nepal
• Variable intensity of sea waves
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9. Solar Energy
 It is defined as the radiating light and heat from the sun that is
harnessed using devices like heater, solar cooker, photovoltaic
cell to convert it to other forms of energy such as electrical
energy and heat.
 Regulates flow of wind and water cycle, provides warmth,
used for heating and cooking purposes, provides light energy.
 20 MW per square Km can be harnessed on the earth
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10. Solar energy
Advantages
• Environmental Sustainability: No pollution
• Economically Viable: Operation and maintenance cost of cells
are very low.
• Accessible: Solar panels are easy to set up and can be made
accessible in remote locations.
• Renewable: Energy is free and abundant in nature.
Limitations
• The efficiency of solar panels is low compared to other
renewable sources of energy.
• Intermittent and unpredictable: can only be harnessed in the
presence of sunlight and gets reduced during cloudy weather.
• Its storage is problematic.
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11. Wind Energy
• Wind power or wind energy is the use of wind to
provide the mechanical power through wind turbines
to turn electric generators and traditionally to do
other work, like milling or pumping.
• Used to generate electricity, to move sailing boats, to
run a pump to draw water from the ground, etc.
Wind turbine blades
may be as much as
60 meters long.
They turn when the
wind blows
A gearbox makes the generator
spin when the blades turn. The
faster the generator spins, the
more electricity it makesAnjan Nepal

12. Wind Energy
Advantages
• Do not cause pollution
• Wind supply will not run out
• Free of cost
Limitations
• Only work in places where there is enough
wind
• Wind does not blow all the time
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13. Biomass energy (Bio-fuel)
• Biomass energy is a renewable source of energy,
derived from burning animal and plant waste
(biomass)
• The dead parts of plant and tress and the waste
materials from animals are called Biomass.
• The mixture of methane, hydrogen, hydrogen
sulfide gases produced on the degradation of
biomass is called biogas.
• The physical installation to produce biogas from
biomass is called biogas plant.
• Used for cooking, lighting, etc
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14. Biomass (Biogas)
Advantages
• Renewable source of energy.
• It reduces the overreliance of fossil fuels.
• Less expensive than fossil fuels.
• Less garbage in landfills.
• Doesn’t pollute the environment
Disadvantages
• Biomass energy is not as efficient as fossil fuels
• It is not entirely clean
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15. Hydroelectricity
• According to statistics, hydroelectricity generated around
16.6% of the global energy resources and constituted about
70% of all the renewable electricity.
• This energy is another alternative source of energy that is
generated by the construction of dams and reservoirs on
the flowing water, the kinetic energy from the flowing
water is used to run the turbines which generate electricity.
• A tidal power which converts the energy of tides and Wave
power which captures the energy from the surface of the
ocean waves for power generation.
• These two forms of hydropower also have huge potential in
electric power generation
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16. Hydroelectricity in Nepal
• Nepal possesses 6000 rivers including rivulets and
tributaries in totaling of about 45,000 km in length and
covering an area of 395,000 ha (48%) which offers
dimensional uses including hydropower development
• Geographically, perennial nature of rivers estimated an
annual runoff accounting up to 170 billion m3 that
flows from steep gradient and rugged topography and
estimated 45,610 MW, feasible for hydropower
generation which is equivalent to 50% of the total
theoretical potential of 83, 290 MW
• Existing production is 650 MW
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17. Hydroelectricity
Advantages
• Renewable
• Pollution Free
• Reliable: Unlike when the sun goes down or when the wind
dies down, water usually has a constant and steady flow
24/7.
• Adjustable: Can produce more energy when it is required
or reduce the energy output when it is not needed.
Limitations
• Energy production varies
• Improper construction may affect aquatic organism
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18. Non-renewable source of energy
• The non-renewable energy is energy from fossil fuels
such as coal, crude oil, natural gas and uranium.
Unlike renewable energy, non renewable energy need
human intervention to make it suitable for
consumption
• Natural Gas: The process of decomposition is longer as
it is conducted to high amounts of pressure and heat.
• Coal: It is formed by the decomposition of trees, plants
and ferns which are hardened due to pressure and
heat.
• Oil: Due to excessive pressure, smaller organisms like
zooplankton and algae are decomposed into an oil.
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19. Fossil fuels
Advantages
• Their burning pollutes the environment.
• It is easily accessible and more compatible.
• The non-renewable source of energy is easy to store.
Disadvantages
• Non-renewable energy cannot be replaced once their
energy source is used up.
• The by-products of non-renewable energy cause
environmental damages. It also increases greenhouses
gases.
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20. Energy crisis in Nepal
• The extreme shortage of available fossil fuels to
meet the ever increasing demand of energy is
called energy crisis.
Reasons:
• Excess use of non-renewable sources of energy
• Growing population requiring more energy
consumption
• Rapid industrialization
• Advanced style of life increases energy
consumption
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21. Solutions for energy crisis
• Controlling population growth
• Use renewable and alternative sources
of energy
• Wise and efficient use of energy.
• Using efficient fuel consuming devices
• Create public awareness to save energy.
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22. Nuclear energy (power)
• Nuclear power is the use of nuclear reactions that
release nuclear energy to generate heat, which most
frequently is then used in steam turbines to produce
electricity in a nuclear power plant.
• Atoms contain huge amounts of energy, and there are two
ways in which this energy can be released.
• One way is to split atomic nuclei in a process called nuclear
fission.
• Another way is to join nuclei together in a process called
nuclear fusion.
• E = mc2 (Einstein’s Theory of relativity) where, E = energy
released, m = mass lost, c= velocity of light in vacuum
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23. Nuclear/ Thermonuclear fusion
• Nuclear fusion is a reaction in which two or more
lighter nuclei/atoms are combined to form a stable
heavy nucleus with the release of large amount of heat
energy.
• The decrease in mass results in release of large amount
of energy
• Inside the Sun, this process begins with protons (which
is simply a lone hydrogen nucleus) and through a series
of steps, these protons fuse together and are turned
into helium. This fusion process occurs inside the core
of the Sun, and the transformation results in a release
of energy that keeps the sun hot
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24. Sun
• Energy radiation per second = 4 x 1026 J/s
• Energy radiation on the earth surface = 1.4 Kw/m2
• Surface temperature = 5700 oC
Evidence of nuclear fusion on the sun:
• There is huge amount of hydrogen
• There is plenty of helium
• Enough temperature (106 K) to split the hydrogen
atoms into plasma state (required to overcome
electrostatic repulsion between lighter nuclei)
• Extreme pressure to combine similar charger nuclei
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25. Nuclear fusion on the sun
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26. Nuclear fission
• Nuclear fission is a reaction in which one heavy
radioactive nucleus is split into two or more nuclei with
the release of large amount of energy.
• Radioactive elements like Uranium (92U235 ), plutonium,
thorium are required for this process
• The reaction in which the particles that initiates a
reaction is also produced in a large number during the
course of reaction and the reaction continues on its own
till one of the reactant is consumed completely is called
chain reaction.
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27. Chain reaction
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28. Differences
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29. Nuclear energy
Advantages
• Used to generate electricity
• Radioactive elements are used to treat cancer
Disadvantages
• Emission of radioactive rays cause serious
health hazards
• Safe disposal of nuclear waste is big problem.
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