There are two main types of energy sources: non-renewable/conventional sources like coal, petroleum and renewable/non-conventional sources like solar, wind and hydropower. Conventional sources are limited and produce pollution while renewable sources are unlimited and cleaner. Some key energy sources discussed are fossil fuels, hydroelectric power, biomass, wind, solar, tidal, geothermal and nuclear energy. Each source has merits like being abundant or producing no emissions but also challenges like high costs or environmental impacts. Thermal power plants, which produce electricity from steam, are also examined along with their advantages and disadvantages.

1. Cambridge International
School
By- Dhruv Arora, Rishab Batra, Navkaran Handa (Class 10 E)
Science HOD- Dinesh Kumar

2. Sources of energy
Class 10 CBSE

3. What are Sources of Energy?
A source of energy is that which is capable of providing enough useful energy at a steady rate
over a long period of time.There are two types of resources non renewable and renewable.

4. Types of Energy

5. Two types of energy sources-
Conventional (Non-renewable)-
Conventional energy means the energy
source which is obtained from fixed
reserves in nature like oil, gas and coal. It
can also be termed as non-renewable
energy. These sources (mainly fossil
fuels) contain carbon compounds and
hence pollute the environment when
burnt. They also require heavy
expenditure..
Eg: Coal, Petroleum
Non-Conventional (Renewable)- Energy
generated by using wind, tides, solar
geothermal heat and biomass including farm
and animal waste as well as human excreta is
known as non-conventional energy. All these
sources are renewable or inexhaustible and
do not cause environment pollution.
Moreover they do not require heavy
expenditure.
Eg: Bio energy, Solar energy, Wind energy

6. What makes a good Source of Energy?

7. Attributes of a good source of energy-
a) A high calorific value i.e the amount of heat produced by burning 1
kg of a substance.
b) It should not produce a lot of smoke.
c) The substance is readily accessible to all.
d) It should do a large amount of work per unit volume or mass
e) It should be easily storable and transportable
f) It should “Be Economical”.

8. Sources of Energy

9. Some sources
These are some sources of energy-
● Fossil Fuels
● Hydro Power Plant
● Biomass
● Wind Energy
● Solar Energy
● Tidal Energy
● Wave Energy
● Ocean Thermal Energy
● Geothermal Energy
● Nuclear Energy

10. Thermal power plant
A thermal power station is a power
station in which heat energy is
converted to electric power. In most of
the places in the world the turbine is
steam-driven. Water is heated, turns
into steam and spins a steam turbine
which drives an electrical generator.
The term thermal is used as heat is
used to generate electrical energy.

11. Merits
● Fuel cost of thermal power plant is
relatively low.
● We can produce thermal energy almost
every where in the world.
● Heat production System is simple
compared to other system.
● Overall system cost effective.
● Easy mechanism.
● Same heat could be reused.
● Easier Maintenance of power station.
● Use of water is prominent here, therefore,
any places with ample supply of water is a
perfect location for installing a thermal
power station.
● Thermal power plant requires
comparatively small space to be installed.
Demerits
● Huge production of Carbon-dioxide (CO2) in
the atmosphere.
● Exhausted gases harms outside
environment badly.
● Low overall efficiency.
● Thermal engines requires huge amount of
lubricating oil that is very expensive.
● Nuclear thermal power plant demands
excessive amount of water for cooling
purpose.
● Coal type thermal power plant requires
comparatively larger duration before it
supply generated power to the grid.
● This type of power station ultimately
responsible for raise in sea water level.

12. Fossil fuels
Fossil fuel is a general term for buried
combustible geologic deposits of
organic materials, formed from decayed
plants and animals that have been
converted to crude oil, coal, natural gas,
or heavy oils by exposure to heat and
pressure in the earth's crust over
hundreds of millions of years.

14. Merits
● Fossil fuels have a very high calorific value.
Thus, burning 1 gm of fossil fuel releases
tremendous amount of energy.
● The reservoirs of fossil fuels are pretty easy
to locate with the help of advanced
equipment and technology.
● Coal is a fossil fuel that is found in
abundance..
● Transportation of fossil fuels that are in
liquid or gaseous forms is very easy.
● Construction of power plants that work on
fossil fuels is also easy.
● Petroleum is the most predominantly
used form of fossil fuels for all types of
vehicles.
● Fossil fuels are easier to extract and
process, hence are cheaper than the non-
conventional forms of energy.
DeMerits
● Although, oil, natural gas and coal are
found in abundance in nature, the
alarming rate at which they are being
consumed has resulted in substantial
depletion of their reservoirs. .
● The hydrocarbons present in the fossil
fuels, release greenhouse gases, such
as methane, etc., which are capable of
damaging the ozone layer.
● carbon monoxide and sulfur dioxide
are responsible for acid rain, which has
spelled disaster for the ecology.
● Coal mining has jeopardized the lives
of several mine workers.
● The depletion of reservoirs has made
the extraction of fossil fuels an
expensive affair.

15. Hydro power plant
Hydropower or hydroelectricity refers to
the conversion of energy from flowing
water into electricity. It is considered a
renewable energy source because the
water cycle is constantly renewed by
the sun. Historically, one of the first
uses of hydro power was for
mechanical milling, such as grinding
grains.

16. Merits
● Hydropower is a fueled by water, so it's a
clean fuel source.
● Hydropower relies on the water cycle,
which is driven by the sun, thus it's a
renewable power source.
● engineers can control the flow of water
through the turbines to produce electricity
on demand
● Impoundment hydropower creates
reservoirs that offer a variety of
recreational opportunities, notably fishing,
swimming, and boating,they provide some
public access to the reservoir to allow the
public to take advantage of these
opportunities. Other benefits may include
water supply and flood control.
Demerits
● Fish populations can be impacted if fish cannot
migrate upstream
● Hydropower can impact water quality and flow.
Hydropower plants can cause low dissolved
oxygen levels in the water, a problem that is
harmful to riparian (riverbank) habitats and is
addressed using various aeration techniques,
which oxygenate the water.
● Hydropower plants can be impacted by drought.
When water is not available, the hydropower
plants can't produce electricity.
● New hydropower facilities impact the local
environment and may compete with other uses
for the land. Those alternative uses may be more
highly valued than electricity generation. Humans,
flora, and fauna may lose their natural habitat.
Local cultures
● Chipko movement

17. Biomass
Biomass is organic material that comes
from plants and animals, and it is a
renewable source of energy.
Biomass contains stored energy from
the sun. Plants absorb the sun's energy
in a process called photosynthesis.
When biomass is burned, the chemical
energy in biomass is released as heat.
Biomass can be burned directly or
converted to liquid biofuels or biogas
that can be burned as fuels.

18. BIO GAS PLANT
● There are two sources of biomass i.e. plant and animal for
biogas production. The biomass obtained from plants is aquatic
or terrestrial in origin, while biomass generated from animals
includes cattle dung manure from poultry, goat, sheep and
slaughter houses, fisheries waste, etc.
● Cattle dung is most potent for biogas production. Besides dung
(gobar), agricultural residue, apple pomade and deteriorated or
dumped wheat grains are also proved to be good source for
biogas production.
● The anaerobic digestion is carried out in an air tight cylindrical
tanks which is called digester. A digester is made up of
concrete bricks and cement or steel. It has a side opening
(charge pit) into which organic materials for digestion are
incorporated.
● There lies a cylindrical container above the digester to collect
the gas. A diagram of single stage digester for gobar gas plant
is shown in. It is noticed that after 50 days, sufficient gas is
produced in gas tank, which is used for house hold purposes.
Usually, digesters are burned in soil in order to benefit from
insulation provided by soil. In cold climate, digester can be
heated.

19. Merits
● Biomass used as a fuel reduces need for
fossil fuels for the production of heat,
steam, and electricity for residential,
industrial and agricultural use.
● Biomass is always available and can be
produced as a renewable resource.
● Biomass fuel from agriculture wastes
maybe a secondary product that adds
value to agricultural crop.
● Growing Biomass crops produce oxygen
and use up carbon dioxide.
● The use of waste materials reduce landfill
disposal and makes more space for
everything else.
● Carbon Dioxide which is released when
Biomass fuel is burned, is taken in by
plants.
● less money spent on foreign oil
Demerits
● Agricultural wastes will not be available if
the basic crop is no longer grown.
● Additional work is needed in areas such as
harvesting methods.
● Land used for energy crops maybe in
demand for other purposes, such as
farming, conservation, housing, resort or
agricultural use.
● Some Biomass conversion projects are
from animal wastes and are relatively
small and therefore are limited.
● Research is needed to reduce the costs of
production of Biomass based fuels.
● Is in some cases is a major cause of
pollution.

20. Wind Energy
Wind power is the use of air flow through wind
turbines to provide the mechanical power to
turn electric generators and traditionally to do
other work, like milling or pumping.
Wind power gives variable power, which is
very consistent from year to year but has
significant variation over shorter time scales. It
is therefore used in conjunction with other
electric power sources to give a reliable
supply.

21. Merits Demerits
● 1. Wind Energy Is Renewable &
Sustainable
● 2. It’s Also Environmentally Friendly
● 3. It Can Reduce Fossil Fuel Consumption
● 4. Wind Energy is Free
● 5. It Has A Small Footprint
● 6. Wind Energy Can Provide Power For
Remote Locations
● 7. Wind Technology is Becoming
Cheaper
● 8. It Is Also Low Maintenance
● 9. The Wind Energy Industry Creates
Jobs
● 1. Installation is Expensive
● 2. Wind Turbines Pose A Threat to Wildlife
● 3. Wind Turbines Create Noise Pollution

22. Solar Energy
Solar energy is radiant light and heat from the
Sun that is harnessed using a range of ever-
evolving technologies such as solar heating,
photovoltaics, solar thermal energy, solar
architecture, molten salt power plants and
artificial photosynthesis.
It is an important source of renewable energy
and its technologies are broadly characterized
as either passive solar or active solar
depending on how they capture and distribute
solar energy or convert it into solar power.
Active solar techniques include the use of
photovoltaic systems, concentrated solar
power and solar water heating to harness the
energy.

23. Merits
● Solar power is pollution free and causes no
greenhouse gases to be emitted after installation.
● Reduced dependence on foreign oil and fossil fuels
● Return on investment unlike paying for utility bills
● Virtually no maintenance as solar panels last over
30 years
● Creates jobs by employing solar panel
manufacturers, solar installers, etc.
● Excess power can be sold back to the power
company if grid intertied
● Ability to live grid free if all power generated
provides enough for the home / building
● Can be installed virtually anywhere
● Use batteries to store extra power for use at night
● Safer than traditional electric current
● Efficiency is always improving so the same size
solar that is available today will become more
efficient tomorrow
Demerits
● High initial costs for material and installation and long
ROI
● Needs lots of space as efficiency is not 100% yet
● No solar power at night so there is a need for a large
battery bank
● Some people think they are ugly (I am definitely not
one of those!)
● Devices that run on DC power directly are more
expensive
● Depending on geographical location the size of the
solar panels vary for the same power generation
● Cloudy days do not produce much energy
● Solar panels are not being massed produced due to
lack of material and technology to lower the cost
enough to be more affordable
● Solar powered cars do not have the same speeds
and power as typical gas powered cars
● Lower production in the winter months

24. Box type Solar Cooker
A solar cooker is a device which uses the energy of
direct sunlight to heat, cook or pasteurize drink
and other food materials.
Black colour is a very good absorber of heat. This
property is used in solar cooker where sunlight
beats on the device and due to its black colour
more heat is absorbed.
Most solar cookers work on the basic principle: Sunlight
is converted to heat energy, that is retained
for cooking. Below is the basic science
for solar panel cookers and solar box cookers.

26. Tidal Energy
Tidal energy is a form of hydropower
that converts the energy obtained from
tides into useful forms of power, mainly
electricity.
Although not yet widely used, tidal
energy has potential for future
electricity generation. Tides are more
predictable than the wind and the sun.
Among sources of renewable energy,
tidal energy has traditionally suffered
from relatively high cost and limited
availability of sites with sufficiently high
tidal ranges or flow velocities, thus
constricting its total availability.

27. Merits
● Environment-friendly
● Highly predictable energy source
● High energy density
● Operational and maintenance costs are low
● Inexhaustible source of energy
Demerits
● High tidal power plant construction costs
● Negative influence on marine life forms
● Location limits
● Variable intensity of sea waves

28. Wave energy
Wave power is the capture of energy of wind
waves to do useful work – for example,
electricity generation, water desalination, or
pumping water.
Wave power is distinct from tidal power,
which captures the energy of the current
caused by the gravitational pull of the Sun
and Moon. Waves and tides are also distinct
from ocean currents which are caused by
other forces including breaking waves, wind,
the Coriolis effect, cabbeling, and differences
in temperature and salinity.

29. Merits
● Clean and green
● Renewable and reliable
● Efficient energy production
● Low operation costs
● No fuel cost
Demerits
● Current high cost of investment
● Reduce usage of sea
● Noise
● Difficult to transmit wave energy
● Slow technology improvements

30. Ocean thermal
energy
Ocean thermal energy conversion
(OTEC) uses the temperature difference
between cooler deep and warmer
shallow or surface seawaters to run a
heat engine and produce useful work,
usually in the form of electricity. OTEC
can operate with a very high capacity
factor and so can operate in base load
mode.

31. Merits
● it is renewable
● it is clean
● eco friendly
● minimal maintenance cost
● easier to access for construction
Demerits
● more expensive than power from fossil fuels
● pipes could damage coral reefs
● less efficient than coal
● space requirements is more
● require high voltage

32. Geothermal energy
Geothermal energy is heat within the earth. The
word geothermal comes from the Greek words
geo (earth) and therme (heat). Geothermal energy
is a renewable energy source because heat is
continuously produced inside the earth. People
use geothermal heat for bathing, to heat buildings,
and to generate electricity.the slow decay of
radioactive particles in the earth's core, a process
that happens in all rocks, produces geothermal
energy.
(image representation on the next page)

33. Merits
● The power output of a
geothermal plant can be
accurately predicted.
● No fuel required after installation
● Cost-competitive in some areas.
● Smallest land footprint of any
major power source.
● It have high potential capacity
Demerits
● High coast for electricity
● It have high distribution cost
● Cost of powering the pump
● May run out of steam

34. Nuclear energy
● Nuclear energy comes from splitting atoms
in a reactor to heat water into steam, turn a
turbine and generate electricity. Nuclear
power plants heat water to produce steam.
The steam is used to spin large turbines
that generate electricity. Nuclear power
plants use heat produced during nuclear
fission to heat water.
● In nuclear fission, atoms are split apart to
form smaller atoms, releasing energy.
Fission takes place inside the reactor of a
nuclear power plant. At the centre of the
reactor is the core, which contains uranium
fuel.

35. Nuclear fission

36. Merits
● It is a reliable source of energy
● It does not need high quantity of water
● They are well suited for large amount of electricity
● Increased reliability of system
Demerits
● The cost of making and nuclear power plant
have high compared to other plants
● Trained people are required to handle it
● It is well suited for varying load conditions
● If the radioactive waste is not disposed
correctly can cause a lot of damage

37. Chipko movement
The Chipko movement or Chipko Andolan was a forest conservation
movement in India. It began in 1970 in Reni village of Chamoli district,
Uttarakhand and went on to become a rallying point for many future
environmental movements all over the world. It created a precedent for
starting nonviolent protest in India, and its success meant that the world
immediately took notice of this non-violent movement, which was to inspire in
time many similar eco-groups by helping to slow down the rapid
deforestation, expose vested interests, increase ecological awareness, and
demonstrate the viability of people power. Above all, it stirred up the existing
civil society in India, which began to address the issues of tribal and
marginalised people. The Chipko Andolan is a movement that practised
methods of Satyagraha where both male and female activists from
Uttarakhand played vital roles, including Gaura Devi, Suraksha Devi, Sudesha
Devi, Bachni Devi and Chandi Prasad Bhatt.