The document discusses different sources of energy, dividing them into renewable and non-renewable categories. It provides details on various non-renewable sources like fossil fuels (coal and petroleum) and nuclear energy, noting issues like radioactive waste and depletion. Renewable sources covered include wind energy, hydroelectricity, solar energy, and biogas, explaining how each harnesses natural processes to generate power in environmentally friendly ways. The document aims to explain the key energy sources and their characteristics.

2.  What is Energy?
 Different sources of energy
 Explanation for each source
 Which is the best source of energy?
 Conclusion

4. The scientific definition of energy is
that “energy is an indirectly observed
physical quantity which is the ability
of body or a system to do work.” On a
logical point of view, we can
understand energy as something which
enables us to do work. If we have
energy then work can be done. Energy
is conserved in systems, meaning that
it can neither be created nor
destroyed but is inter-convertible
into its different forms. It comes from
many sources and in many forms. The

6. There are two types of energy
sources, Renewable and Non-Renewable
sources. Renewable energy sources are
sources that can be replenished or which
are available naturally in excess. Non-
Renewable energy sources are limited in
their availability. Renewable energy
sources are more „environment-friendly‟ as
they do not cause any natural imbalances.
Whereas acquisition and usage of Non-
Renewable energy sources causes
disruption and disturbs the balance of
environment. List of Energy sources
according to their types are
• Non-Renewable Energy sources:
Fossil Fuel
Nuclear Energy
• Renewable Energy sources are:

8. Fossil Fuels, as the name suggests are
formed by fossils which are compressed by
the pressure of the earth‟s crust under
the duration of thousands of years and so
they cannot be replaced as soon as they
have been consumed. When coal is burnt, it
releases a lot of energy which is used to
convert water to steam and the steam is
made to run turbines to produce
electricity. Petroleum finds it place in the
combustion chambers of an internal
combustion engine to power various
machines. Also the usage of such fossil

10. Nuclear energy is harvested from Uranium-
238 which is extracted from the sparsely
present Uranium ores. The Uranium extracted
from these ores is used in nuclear
reactors, the heat from which produces
steam which runs turbines to produce
electricity. Uranium is mined only 19
countries and comprises only 6% contribution
of energy in the world. However, a downside
of nuclear energy is radioactive waste. The
mistreatment of radioactive waste leads to
devastating consequences which include
cancer. Even damage to the reaction
chambers by either natural or man made
disasters causes radioactive contamination

12. WIND ENERGY
• All renewable energy (except tidal and geothermal power),
ultimately comes from the sun
• The earth receives 1.74 x 1017 watts of power (per hour) from the
sun
• About one or 2 percent of this energy is converted to wind
energy (which is about 50-100 times more than the energy
converted to biomass by all plants on earth
• Differential heating of the earth’s surface
and atmosphere induces vertical and horizontal
air currents that are affected by the earth’s
rotation and contours of the land  WIND.
~ e.g.: Land Sea Breeze Cycle

13. • Winds are influenced by the ground surface at altitudes up to
100 meters.
• Wind is slowed by the surface roughness and obstacles.
• When dealing with wind energy, we are concerned with
surface winds.
• A wind turbine obtains its power input by converting the
force of the wind into a torque (turning force) acting on the
rotor blades.
• The amount of energy which the wind transfers to the rotor
depends on the density of the air, the rotor area, and the wind
speed.
• The kinetic energy of a moving body is proportional to its
mass (or weight). The kinetic energy in the wind thus depends
on the density of the air, i.e. its mass per unit of volume.
In other words, the "heavier" the air, the more energy is
received by the turbine.
•Therefore the wind energy is the most important renewable
resource on the Earth.

15. Hydroelectricity is the
term referring to
electricity generated
by hydropower; the
production of
electrical power
through the use of the
gravitational force of
falling or flowing
water. It is the most
widely used form of
renewable energy,
accounting for 16 % of
global electricity
generation – 3,427
terawatt-hours of
The major advantage of
hydroelectricity is
elimination of the cost
of fuel. The cost of
operating a
hydroelectric plant is
nearly immune to
increases in the cost of
fossil fuels such as
oil, natural gas or

17. Solar energy, radiant light and
heat from the sun, is harnessed
using a range of ever-evolving
technologies such as solar heating,
solar photovoltaic, solar thermal
electricity, solar architecture and
artificial photosynthesis. Solar
energy refers primarily to the use
of solar radiation for practical
ends. However, all renewable
energies, other than geothermal
and tidal, derive their energy from
the sun.
Solar technologies are broadly
characterized as either passive or
active depending on the way they
capture, convert and distribute
sunlight. Active solar techniques
use photovoltaic panels, pumps, and
fans to convert sunlight into useful
outputs. Passive solar techniques

19. Biogas typically refers to a mixture of
gases produced by the breakdown of
organic matter in the absence of
oxygen. Biogas can be produced from
regionally available raw materials
such as recycled waste. It is a
renewable energy source and in many
cases exerts a very small carbon
footprint. Biogas is produced by
anaerobic digestion with anaerobic
bacteria or fermentation of
biodegradable materials such as
manure, sewage, municipal waste, green
waste, plant material, and crops. It is
primarily methane (CH4) and carbon
dioxide (CO2) and may have small
amounts of hydrogen sulphide (H2S),
moisture and siloxanes. The gases
methane. hydrogen, and carbon monoxide
(CO) can be combusted or oxidized with