By Dr.

Rajwant Kaur
 Natural Resources
• Anything thing from nature that fulfills the needs of
human is a natural resource. E.g. solar energy, fresh
air, fresh water, plants, animals, fertile soil, wood,
minerals, fossil fuels, rivers etc..
• Are classified into two categories:

• Renewable resources: resources that are replaced by

natural processes fairly rapidly on scale of days to
centuries and can be used forever, provided they are
not overexploited in short term. E.g. fresh water, fertile
soil, fresh air, trees in forests etc..
• Non-renewable resources: resources that are not
replaced by natural processes within a reasonable
period of time, rather it takes millions of years. They are
present in limited supply and get depleted by use. E.g.
fossil fuels (coal, petroleum, natural gas) and minerals.
 Land Resource
• Most of the Earth’s land area is rural or non-
urban, that are sparsely populated by human.
• These areas include natural ecosystems like
forests, grasslands, deserts, and wetlands.
• These provide vital ecosystem services to
humans:
– habitat for wildlife and protect biodiversity,
– flood and soil erosion control,
– Regulation of biogeochemical cycles
– groundwater recharge,
– breakdown of pollutants,
– Provide fertile soil, food, medicines, and raw
materials for commercial production
– education, and research,
– recreation.
 Land Use
• Land use is to modify, manage or convert a
natural land into built environments for
satisfying human needs. e.g. developing
cities, industries, croplands, pasturelands.
• Of the Earth’s total land area,
• Urban area – 3%
• Agriculture – 12%
• Pastureland – 26%
• Unsuitable area (deserts, rocks, tundra, ice)
– 30%
• Forests, wetlands, lakes – 29%
 Land use in India

• India has total land area of 3.28

million sq. km
• Of the total land area of India,
Total cultivable land 58.5%
Pastureland 3.4%
Land under tree crops 1.1%
Urban area 5.6 %
Barren and uncultivable 8.6%
wasteland
Forests 22.8% (far less than 33%
limit)
 Land degradation
• Human population is increasing with time, so are the
demands for residential area, cultivable land, pastureland,
industries etc. However, land is a limited/ finite resource.

• Land degradation is the decline in potential productivity or

utility of a land by natural or human activities.

• Causes of land degradation:

– Deforestation: for many reasons like subsistence farming, dam
construction, mining etc., makes land vulnerable to soil erosion

– Overgrazing: when too many animals graze on grasslands, the

plants are grazed to an extent that they are not able to recover
and, die. This makes soil vulnerable to soil erosion.
 Land degradation
– Agricultural Practices:
• Monoculture.

• Excessive fertilizers and pesticides

• Over-irrigation: Farmers often over-irrigate the fields to provide proper moisture and sometime to
dilute salt content but due to poor drainage and poor quality water, it results into water-logged
conditions. This affects crop by stopping gaseous exchange. This also cause increase in salt
content of the top layer of soil as the water evaporates, this is known as Salinization.

– Waste disposal and Soil pollution:

With increasing population, more and more land is being converted to industrial and
urban area, that result in generation of more and more industrial and urban solid waste
which are to be managed. When the are disposed without segregation and treatment on
land, it contaminates the soil and ground water. The solid waste are generally managed in
sanitary landfill sites, which itself require a lot of land.
 Soil Erosion
• Removal of the top fertile layer of the soil from land is called
Soil Erosion.

• Two main agents of soil erosion are: Water & Wind

• It is a natural process but accelerated by human activities

such as
1. Deforestation: Plant roots hold the soil in place, stems and
leaves decrease the impact of rainfall. Clear-cutting large
forested area leads to open land without vegetation cover,
where soil becomes dry and prone to erosion.

2. Overgrazing
3. Overcultivation
 Soil erosion
• It is a significant problem worldwide
• It results in an annual loss of as much as 75
billion metric tons of topsoil around the world.
• In India, 6.6 billion metric tons and in China, 5.5
billion metric tons of soil is lost annually by
erosion.
• Case study: The American Dust Bowl: In 1930s,
the great plains of North America (semiarid land)
which were earlier occupied by grasses (prairie)
but converted to wheat cultivation, experienced
severe drought. Strong dry winds of high
magnitude blew topsoil eastwards for 100s of
kilometers.
 Desertification
• The degradation of once fertile grassland,
agricultural land, or forest especially in arid
and semiarid regions, into non-productive
desert is called Desertification.
• It is a type of land degradation, it occurs
mainly due to
– Natural causes (Prolonged adverse climatic
conditions like extended droughts, wildfires), and
– human activities (like deforestation, overgrazing,
over-cultivation, over-irrigation and soil
salinization, all of which make soil vulnerable to
soil erosion)
• About 41% of the terrestrial land surface is
made up of arid and semiarid lands
(drylands) distributed over more than 110
countries which are threatened by
desertificaton. E.g. expanding deserts in
China, India, Iran, Mongolia, and Pakistan.

• Deserts are increasing at a rate of 6 million

ha annually in the world. The desert of
Rajasthan has advanced 1500km eastwards
during last 800 years, and the Sahara desert
in Africa expands southward at a rate of
10km per year.
 Case Study

• Desertification in
Sahel: Livestock in
Mali, Africa, have eaten
all the ground cover.
The dead trees were
stripped of branches to
feed livestock and
provide firewood.
Overexploitation by
desperately poor people,
in combination with
extended drought, is
increasing the amount
of unproductive desert
area in the Sahel.
• Expanding Gobi desert in China:
• Impacts :
– It makes areas prone to floods, and further soil erosion by wind and water.
– It results in loss of biodiversity.
– Due to loss of vegetation, it promotes global warming and climate change.
– About 35% of the human population lives in these drylands that border
deserts. Due to desertification, agricultural productivity declines and hunger
and poverty increases, which forces people to emigrate. According to UN
Environment Program, about 135 million people worldwide are in danger of
displacement due to desertification.
– The world bank estimates that desertification costs about $42.3 billion per
year in economic losses.
• Control: Desertification can be slowed down, and reclaimed by using
improved management practices. It involves:
– Preparation of desertification hazard map,
– Reducing the pressure of grazing and harvesting, bringing it down within a
sustainable range
– Stabilizing the sand dunes
– Construction of windbreaks or shelter-belts in the windward side of cropped
land and settlements.
– Treatment of saline soil and water-logged land.
• United Nations Convention to Combat
Desertification (UNCCD):
– The ratification of the UNCCD by June 1994 was a
major poet-Rio accomplishment, providing a
mechanism to assess and respond to the problems of
dryland degradation around the world.
– 17th June became World Day to Combat
Desertification.
– It emphasized on full participation of people most
affected by desertification, specifically women.
 Soil conservation and reclamation
practices
• Conservation tillage
• Crop rotation
• Contour plowing
• Strip cropping Conservation tillage Strip cropping
• Terracing
• Use of organic
fertilizers
• Shelterbelts/windbre
aks
• Agroforestry Terracing Shelterbelts
Forest resource
• Forest: those areas having an extent of at least
0.5 ha with tree crown of more than 10% (FAO
2001).
• Due to large scale land use change, forest area
has reduced to only 29% of the Earth’s total land
area.
• Of which,
– 47% occur in tropical zone
– 9% in sub-tropics,
– 11% in temperate, and
– 33% in the boreal zone
Forest cover in India
• At the beginning of 20th century, about 30% land in
India was covered with forests
• But by the end of 20th century, it has reduced to 22.8%
which is far less than the national goal of at least 33%
(at least 60% on hills and 20% on plains) of total
geographical area as per National Forest Policy (1988).
• Of the existing forests, 60% are dense forests and rest
are open degraded forest
• Per Capita forest available in India is 0.06 ha, compared
to 0.64 ha per person over world (on an average).
 Importance of forests: ecosystem
services
• Productive value:
– Production of fuel wood: fuel wood is required by 1.5 billion people
across the world as primary energy source. It is estimated to be 2600
million m3
– Production of industrial wood: for construction of houses, furniture,
ships, carts, carraiges, railways, paper, plywood, sports goods etc. The
developed countries produce less but consume about 80% of the total
production.
– Production of non-wood products: like food, fibre, honey, medicinal
plants, spices, resins, tannins, gums etc.
• Protective value:
– Control of floods, droughts, and soil erosion.
– Help in ground water recharge
– Prevent/ reduce pollution
– Provide habitat for wildlife
• Regulatory value:
– Regulate C-cycle; Photosynthesis provide O2 which is important for
survival of all living organisms; forests act as sinks of CO2 so help in
reducing global warming and climate change
– Regulate H2O cycle by transpiration; also help in absorption of rain
water by soil and increase in ground water; forested watersheds act as
giant sponges that absorb rain water and slow down the run off. The
absorbed water is slowly released into the streams;
– Moderate the climate: forests act as thermostat of nature.
Transpiration increases humidity in the air, lowering the temperature,
and also help in rain.

• Informational value:
– provide educational and research opportunities
– Provide genetic diversity

• Other contributions: provide employment to locals; important for

tourism, recreational, aesthetic and spiritual activities.
Deforestation
• World’s forest cover is decreasing rapidly due to deforestattion
especially in tropics.
• The tropics have lost more than 40% of the forest cover due to
deforestation.
• In the tropical moist forest area, rate of clearance was 14.2 million
ha per year (during 1990-2000) i.e. 1% is lost each year.
• Causes of deforestation: Increased population pressure for
expansion of agriculture and rangelands, urbanization,
industrialization, mining, dam construction, excessive commercial
use of timber, fuelwood, non-timber forest products
• To fulfill these demands, a large number of tropical countries
exporting wood products have decreased their forest cover from 33
to 10% by the end of 20th century. India is losing 1.5 million ha of
forest cover each year.
Causes of deforestation
• Population pressure for agricultural land:
– shifting (jhum) cultivation is causing loss of forests. In
India, it is practiced in North-east states and M.P.
Under this, local tribals clear some part of the forest ,
cultivate it for 2-3years, abandon it and move to new
areas of forest. The forest fallows donot get chance to
revert back as forest due to population pressure.
About 240 million ha of closed forest across the world
are under this practice.
• Fuel wood requirement: of poor people in tropics
in increasing.
• Industrial demand for wood
• Developmental projects: like dams, river valley
projects, reservoirs, hydroelectric projects,
construction of highways, roads, rail tracks, irrigation
canals etc. cause massive forest destruction.
• Expansion of the grazing land: the forest area is
converted to rangeland for grazing of cattles. India has
large livestock population but grazing land is
insufficient to meet the demand. The livestock grazes
in the forests, killing seedlings, compacting soil and
causing decreased water absorbing capacity of soil.
• Quarrying and mining operations: cause extreme
damage to vegetation. E.g. coal mining in Jharia,
Raniganj and Singrauli areas have caused extensive
deforestation in Jharkhand
• Forest fires: may be natural or man-made
Environmental Impacts of
deforestation
– Loss of wildlife and biodiversity
– Decreased water absorption by soil, increased surface run-off of
rain water, that leads to increased soil erosion and loss of soil
fertility, leading to desertification. Cherrapunji, once wettest
place on the Earth now has no water to drink. Due to
deforestation of the hill slopes, and subsequent soil erosion and
extreme surface run-off, hill slopes have become deserts.
– Increased soil erosion results in silting (silt deposition) of rivers,
reduces productivity and biodiversity of rivers, cause flash
floods
– Low ground water recharge
– Disturbed water cycle and frequent floods and droughts
– Disturbed C-cycle, increased atmospheric CO2, increased global
warming and climate change
– Exposed land become prone to landslides
Social Impacts of deforestation
– It threatens indigenous people whose culture and
survival depends upon forests.
– Silting in the dam reservoir due to deposition
sediments eroded from cleared area with surface
run-off rain water. It reduces the capacity of
reservoir and so the production of electricity.
– Landslides, floods and droughts affect the local
people, their property and lives. E.g. June 2013
Uttrakhand flood case
Impacts of mining
• Mining is done to extract minerals or coal from deep deposits in soil by using sub-
surface mining or from shallow deposits by surface mining. Some important mines
in India include Jaduguda uranium mine (Jharkhand), Jharia coal mines
(Jharkhand), Sukinda chromite mine (Odisha), Kudremukh iron ore mine
(Karnataka), East coast bauxite mine (Odisha), North-Eastern Coal Fields (Assam).
Impacts of mining are:
• Deforestation, which has several serious ecological losses as already discussed.
• Soil and water pollution: Rocks rich in minerals often contain high concentration
of heavy metals like Arsenic and Lead. When rain water seeps through sulphide
minerals exposed in mine wastes, H2SO4 is produced that in turn dissolves other
toxic substances like lead, arsenic, Cadmium in the spoil banks of coal and metal
ore mines. These acids and highly toxic substances called acid mine drainage, are
washed into soil, and water (surface and ground both), causing soil and water
pollution
• Air pollution: due to emission of mine dust, harmful gases, and air pollutants
emitted by transport vehicles. The suspended particulate matter (SPM), Sox, soot,
arsenic, Cadmium, lead etc. increase in atmosphere near mines and smelters
• Occupational health hazards: Mine workers suffer from various respiratory and
skin diseases like silicosis, asbestosis, black lung disease.
• Displacement of local/tribal people: Mining area has to be evacuated, tribal
people lose their home, property, and culture.
Dams: benefits and impacts
• According to World Commission on Dam Report (2000),
there are 45000 large dams in 140 countries.
• Of these, India has 4391 dams, 9% of total
• The first Indian PM, Jawahar Lal nehru, called dams as the
Temples of modern India.
• Various benefits are:
– Generation of hydroelectric power
– Irrigation during dry periods of needy areas
– Control of floods by regulating flow of rain water stored in
reservoirs
– Control droughts by supplying water canals to affected areas
– Year round supply of drinking water
– Fisheries in reservoir
• Impacts: Despite their benefits, dams have huge environmental
losses. Dam affects river ecology both above the dam (reservoir)
and below the dam (the river).
– Deforestation, and its environmental impacts like loss of biodiversity,
soil erosion, (already discussed)
– Expansion of reservoir submerge adjoining large fertile land area,
forests, and human settlements
– Submergence of forests result in loss of habitat of wildlife and tribal
people
– the enormous weight of water behind the dam could trigger seismic
activity that might crack the dam and cause floods
– Heavy deposition of sediment occurs in the reservoir due soil erosion.
Increased growth of aquatic weeds in the reservoir due to
sedimentation
– Stagnation and waterlogging near reservoirs
– Spread of water related diseases like malaria as waterlogged areas
provide breeding sites of mosquitoes
– the water that passes the dam does not have its normal sediment
load. As a result, downstream river flora and fauna decline due to lack
nutrients.
– Also the loss of land fertility along the river due to reduced sediments
Water resource
• Earth is a blue planet, as its 3/4th surface is
covered with water
• Water is life; it is important for survival of all
living organisms
• Water resource:
– Sea water (97.5%)
– Fresh water (2.5%)
• Ice caps & glaciers, rivers, streams, lakes, ponds,
wetlands, ground water, soil moisture, atmospheric
water vapours
• The water cycle continually renews the supply
of fresh water on land which is essential for
terrestrial organisms
• Most fresh water is unavailable for easy
consumption as it is frozen (1.97%).
• Only available fresh water is 0.53% (surface and
ground water) of the Earth’s water.
Fresh water
• Surface water (सतही जल): is the water found on Earth’s surface in
streams, rivers, lakes, ponds, reservoirs, and watersheds. Most of the
surface water originates from rain water or snowfall and melting of glaciers.
• Ground water (भूमिगत जल): the rainwater that seeps into the soil and
finds its way down the cracks and spaces in sand, gravel, or rock until it is
stopped by an impermeable layer; there it accumulates as groundwater.
The underground porous layers of sand, gravel or rock in which ground
water is stored are called aquifers (भूमिगत जल स्रोत/ जलभत ृ ).
• Aquifers are of two types:
– Unconfined aquifers (असंकुचित जलभत ृ ): ground water storage area between
porous soil layers and impermeable rock layer.
– Confined aquifers (संकुचित जलभृत): ground water storage area between two
impermeable rock layers.
• Most groundwater is considered as non-renewable resource because it has
taken 100-1000s of years to accumulate, and usually only a small portion of
it is replaced each year by percolation of rain water.
• Groundwater also flows horizontally through the permeable sediments,
rocks, eventually entering into the rivers, wetlands, springs and or ocean.
So, some of the surface water is also comes from groundwater. Thus,
surface and ground water are interrelated parts of H2O cycle.
Aquifers (जलभत
ृ )
 Water Use
• We depend on freshwater for numerous purposes
viz. drinking, cooking, washing, transportation,
irrigation, manufacturing, mining, energy
production, and waste disposal
• Water use can be broadly classified under three
sectors: World India
– Agricultural use 71% 95%

– Industrial use 20% 4%

– Domestic and municipal use 9% 1%

• Freshwater use is increasing world wide, as the

population is increasing and individuals are using
more water.
• Global rate of water use
has accelerated
markedly after 1940.
Total freshwater use has
increased 10 times from
1900 to 1999.
• Fresh water is a limited
resource, such high rate
of water use cannot be
sustained for a long
period.
• Around the world, about 1.1 billion people live without access
to water- many have fewer than 10L of clean water per day.
• Water consumption varies among countries, ranging from
several liters per person per day in areas of acute shortage, to
several hundred liters per person per day in some highly
developed nations. A typical American uses about 340 L each
day.
• Forecasts are that by 2025 as much as 2/3rd of the world’s
population will be affected by moderate to severe water
scarcity unless appropriate mitigation measures are taken.
• At present at least 200 cities across the world are facing
serious water crisis, of these 11 cities are moving quickly
towards ‘Day Zero’: Cape town (South Africa), Bengaluru
(India), Beijing (China), Mexico City (Mexico), Sanaa (Yemen),
Nairobi (Kenya), Istanbul (Turkey), Sao Paulo (Brazil), Karachi
(Pakistan), Buenos Aires (Argentina) and Kabul (Afghanistan).
Water resource: problems
• Increasing population pressure
• Over-exploitation
• Floods
• Droughts
• Conflicts over water
• Water pollution
Overexploitation of surface and
ground water
• Due to increasing population pressure, water demand for various
purposes is also increasing especially to fulfill demand of food and
drinking water, so more freshwater resources (surface and ground
water) are diverted towards agriculture (irrigation), resulting in
overutilization.
• When surface water is overdrawn, wetlands dry up. Natural
wetlands play many roles like breeding ground for many bird
species, animals. Estuaries become saltier, which decreases the
productivity of this ecosystem.
• Overutilization of ground water, results in aquifer depletion. Aquifer
depletion may result in subsidence or sinking of land above it. In
coastal areas aquifer depletion results in saltwater intrusion, i.e.
entry of saltywater from nearby ocean into the well water.
• Due to overgrazing of pastures, soil gets dry and compacted,
reducing water absorption by soil during rain, reducing ground
water recharge and increasing soil erosion. This reduces
productivity of the land and so more forests are cleared.
Floods
• A flood is defined as overflow of river water due to
heavy rainfall, melting of snow or ice or a combination
of all.
• Flooding is a natural phenomena, which used to be
beneficial in the past. Because the excess water of
swollen river floods the area surrounding the river. This
surrounding area (called as floodplain) acts as a buffer
between river and developed area, as its absorbs the
excess river water like a sponge and releases slowly
into the rivers. Secondly, when the water recedes, thin
layer of sediments rich in nutrients get deposited on
the soil surface, making this land highly fertile.
• Modern floods result from interactions between
human activities and natural phenomena, and so are
more disastrous in terms of loss of lives and property.
• Human activities promoting floods and flood damage
are
– Deforestation (decrease in rain water absorption, increase
in surface run-off, increase in soil erosion, silting the rivers,
reducing carrying capacity of river, causing floods in low
lands) and
– Human settlements in floodplains (buildings and roads do
not absorb rain water, so surface run-off increases, causing
flooding and damage)
– Alteration of natural path of river: Natural path of river is
meandering which slows down the flow of water, but
when rivers are channelized through straight path, flow
increases.
• E.g. Uttrakhand 2013 flood
• In India, the most flood-prone areas are the
Brahmaputra-Ganga-Meghna basins which
carry 60% of the country’s total river flow into
Indo-Gangetic-Brahmaputra plains.
• About 47% of the country’s population lives in
this basin, which are subject flood damage.
Droughts
• Drought is a normal recurrent feature of nature occurring almost
everywhere but its extent varies from region to region.
• It is difficult to define drought because it depends on the difference in
regions, needs, and disciplinary perspectives
• In general, drought is defined as an extended period of time (a season,
year, several years) of deficient precipitation relative to the statistical
multiyear average of the region .
• Droughts can be of three types:
– Meteorological drought (associated with degree of dryness and duration of
dry period)
– Hydrological (associated with degree or period of precipitation and short
rainfall supplying water to surface or subsurface)
– Agricultural (links various characteristics of meteorological (or hydrological)
drought to agricultural impacts, focusing on precipitation shortages,
differences between actual and potential evapo-transpiration, soil water
deficits, reduced groundwater or reservoir levels, and so forth.
Causes and Impacts of drought
• Causes: Natural (climatic variation), and human activities that
disturb the hydrologic cycle:
– Deforestation (reduces transpiration, decrease rainfall; reduce CO2
uptake, leading global warming that also alters patterns of rainfall and
temperature over time and space (climate change) ,
– Urbanization (reduction of ground water recharge),
– Industrialization (reduction of ground water recharge), ,
– Overgrazing
– Soil erosion and silting of rivers,

• Impacts:
– Loss/ migration of species,
– Food insecurity, famine, malnutrition, emigration of people e.g.
prolonged droughts in Sahel (Africa)
Conflicts over water
• Water is highly indispensable and its distribution is not
equal across the states or countries; this results into
conflicts over water
• So, increased demand of water for agricultural,,
industrial, and domestic use, appears to be the main
cause of conflict between its beneficiaries
• Conflict may also arise from drive to possess or control
another country’s water resource
• Sometimes water resources are used as instruments of
war, e.g. In 1969, Israel attacked the East Ghor Canal in
Jordan to prevent diversion of water
Energy Resource (उजजा संसजधन)
• Energy is defined as the ability to do work (कार्य करने की क्षमता को उजाय कहते हैं).

• We require energy for everything, to move, to build things, to heat, to cool, to illuminate or living
and work places (हर कार्य को करने के ललए उजाय की आवश्र्कता होती है , जै से- हहलना, वस्तुओं
आहि का ननमायण करना, ठं डा करना, रहने और काम करने की जगहों को प्रकालित करना).

• Energy is required to plant, water, harvest, process, ship, and store food (कृषि में बीज लगाने,
लसंचाई करने, फसल काटने, इत्र्ाहि के ललए भी उजाय की आवश्र्कता होती है ).

• Energy is needed to capture energy e.g. to drill and pump petroleum oil, to mine coal and uranium,
to prepare solar panels, to install wind mills, to make dams etc (उजाय की आवश्र्कता उजाय प्राप्त
करने के ललए भी होती है , जै से- पेट्रोललर्म तेल ड्रिल और पंप करने के ललए, कोर्ला और र्ूरेननर्म
के खिान के ललए, सौर पैनल तैर्ार करने के ललए, पवन चक्ककर्ों को स्थाषपत करने के ललए, बांध
ननमायण के ललए) .

• The main source of energy on Earth is Sun. About 99.8% of energy on Earth comes from Sun (पथ्ृ वी
पर उजाय का मुख्र् स्रोत केवल सूर्य है , पथ्ृ वी पर उपलब्ध उजाय का लगभग 99.8% भाग सूर्य से ही
आता है ).
 Energy consumption & Growing energy
needs (ऊजाय की खपत और बढ़ती उजाय की
जरूरतें)
• Per capita energy consumption varies enormously
among the countries. An average person in
developed countries consumes 300 GJ per year,
while an average person in poor countries like
Bhutan, Nepal, or Ethiopia consumes <1 GJ per
year.
• Energy consumption of a country is considered as
an index of its development; highly developed
countries in which world’s less than 20%
population lives, consumed 60% of the
commercial energy consumed worldwide (2010).
• With increasing population, advancement in
technology, and our changing lifestyle from simple
to luxurious, energy consumption is also
increasing.
• This increase is not same across the countries.
China has more than doubled its energy
consumption over past decade, India now uses
50% more energy than it did in 2000. On the other
hand, the energy use is same as it was a decade
ago in US, Germany and Japan.
• GDP: the total value of goods produced and
services provided in a country during one year.
• For early man, only source of energy was his physical
energy
• With advancement in technology, man started using
other energy sources, like wood (to produce fire), wind
(to operate windmill), water (to operate water mill)
• Invention of steam engines, replaced wood by coal for
burning and producing heat, coal was further replaced
by oil.
• Further, with increasing population and technological
advancement, demand for fossil fuels increased.
• As these fossil fuels are limited, non-renewable, very
expensive, need to explore other alternative sources of
energy has been realized.
 Renewable and non-renewable energy sources
(नवीकरणीर् एवम अनवीकरणीर् उजाय स्रोत)
• A source of energy is one that can provide adequate amount of energy in a usable form over a long
period of time (उजाय का स्रोत उसे कहा जाता है , क्जस से लम्बे समर् तक उपर्ोगी रूप में पर्ायप्त
उजाय लमलती रहे).

• They are classified as (र्ह िो प्रकार के होते है ):

– Renewable energy source (नवीकरणीर् उजाय स्रोत): that are replaced by natural processes fairly rapidly on
scale of days to centuries and can be used forever, provided they are not overexploited in short term (वे स्रोत
जो प्राकृनतक क्रिर्ाओं द्वारा िीघ्र ही (हिन र्ा सहिर्ों में) पन
ु ः ननलमयत क्रकर्े जाते हैं, अगर इनका अत्र्धधक
िोहन न क्रकर्ा जार्े तो, इन्हें सिा इस्तेमाल क्रकर्ा जा सकता है). E.g. solar energy (सौर उजाय), wind energy
(पवन उजाय), hydropower (जल उजाय), tidal energy (ज्वार उजाय), geothermal energy (भत
ू ापीर् उजाय), ocean
thermal energy (समद्र
ु तापीर् उजाय), wood (लकड़ी), biomass (जैव भार), biofuel (जैषवक इंधन)

– Non-renewable energy source (अनवीकरणीर् उजाय स्रोत): that are not replaced by natural processes within a
reasonable period of time, rather it takes millions of years They are present in limited supply and get
depleted by use(वे स्रोत जो प्राकृनतक क्रिर्ाओं द्वारा िीघ्र ही (हिन र्ा सहिर्ों में) पन
ु ः ननलमयत नहीं क्रकर्े
जा सकते हैं, इन्हें तैर्ार होने में अरबों साल लगते , र्ह लसलमत मात्रा में होते हैं, और इस्तेमाल करने से
कम होते जा रहे हैं).. E.g. fossil fuels (coal, petroleum, natural gas) (जीवाश्म इंधन जैसे कोर्ला, पेट्रोललर्म,
प्राकृनतक गैस) and minerals (खननज Uranium and thorium (nuclear fuel, आक्ववक इंधन))
Renewable vs. Non-Renewable energy
Renewable energy Non-Renewable energy

Can be regenerated by natural processes Cannot be regenerated rapidly, rather

fairly rapidly e.g. solar energy (सौर उजाय), takes millions of years to renew. E.g. fossil
wind energy (पवन उजाय), hydropower fuels (coal, petroleum, natural gas)
(जल उजाय), tidal energy (ज्वार उजाय), (जीवाश्म इंधन जैसे कोर्ला, पेट्रोललर्म,
geothermal energy (भूतापीर् उजाय), ocean प्राकृनतक गैस) and minerals (खननज
thermal energy (समद्र ु तापीर् उजाय), Uranium and thorium (nuclear fuel,
wood (लकड़ी), biomass (जैव भार), आक्ववक इंधन))
biofuel (जैषवक इंधन)

Environment-friendly except burning of Cause air pollution except nuclear energy

wood

Cheaper though installation and Expensive

establishment cost are very high

Has lesser risk of disaster Have high risk of disaster

Renewable energy: Solar energy
• Solar energy is used either directly or indirectly
• Direct solar energy:
– Solar cookers
– Passive solar heating: solar energy is used to heat
buildings without need for pumps or fans to distribute
the heat
– Active solar heating: in this, a series of collection
devices mounted on a roof or a field are used to
gather solar energy, and pumps or fans distribute the
collected heat. Collection device is a panel or plate of
black metal, which absorbs solar energy. Used for
heating water for buildings or swimming pools.
• Solar thermal electric generation: a means of producing electricity
in which the sun’s energy is concentrated by trough-shaped mirrors
or lenses to either heat a fluid-filled (oil) pipe or drive a Stirling
engine.
• Heated oil (390°C) is circulated to a water storage system, water
becomes steam, which turns the turbine to generate electricity.
• In stirling engine, fluid in a cylinder expands, driving piston that
turns the shaft, producing electricity.
• World’s largest solar thermal system is in Mojave Desert in
Southern California. Cost ranges from $ 0.05 to $0.13 per kWh.
Photovoltaic solar cells:
• convert solar energy into electricity. Contain a thin film of
semiconductor like silicon or gallium arsenide that generates
electricity when absorbs solar energy. Currently , they
account for only 0.7% of the global electricity.
• Does not cause air pollution and require minimal
maintenance. Used to power satellites, highway signals,
watches, calculators , irrigation pumps, etc.
• Limitation: 1) has very low efficiency in converting solar
energy to electricity (15-18%). So for large scale production,
large area is required. 2) cost of manufacturing solar panels is
comparatively higher ($0.15 -$0.25 per kWh) but it is
decreasing with technological advancement.
Indirect Solar Energy
• Biomass energy
• Wind Energy
• Hydropower
• Ocean thermal energy
Biomass energy
• Biomass, one of the oldest fuels known
• E.g. fast-growing plants, algal crops, crop wastes, sawdust, wood chips, animal
wastes, and the wood.
• At least half of the human population depend on biomass as their main source of
energy
• Biogas: animal waste and agricultural waste is converted into biogas in biogas
digesters, where microbial decomposition of this waste takes place under
anaerobic conditions. Biogas contains mixture of gases, mainly methane. It is a
clean fuel. In India and China, it is being used for cooking and lighting.
• Liquid fuels like methanol and ethanol, can also be produced from biomass (rice
straw, residues of processed sugarcane, sewage sludge). They are used in internal
combustion engines. Automotive fuels require at least 10% ethanol.
• Biodiesel: made from plant or animal oils, is becoming popular alternate fuel for
diesel engines in trucks, farm equipments, boats. It is cleaner than diesel.
• Advantages: reduces waste-disposal problem; biomass combustion produces less S
and ash compared to coal.
• Disadvantages: it increases competition for land between food crops and energy
crops; wood combustion will cause more deforestation, soil erosion ; crop residues
left in field increase productivity of the land.
Wind energy
• Wind is caused by heating of Earth’s surface by Sun, so it is indirect
form of solar energy.
• Like solar energy, it is also highly dispersed form of energy.
• It is cost competitive with many forms of conventional energy
sources; as turbines have become larger and more efficient, costs of
generating wind energy has declined from $0.40 per kWh in 1980 to
$0.06kWh in 2010.
• Germany and US are the world’s top producers of wind energy
• Advantages: does not cause air pollution but birds and bats get
killed when collide with turbine
• Disadvantage: wind is not optimum every where on Earth;
developing new technologies to store and distribute this energy.
Hydropower
• र्ह सौर ऊजाय का एक अप्रत्र्क्ष रूप भी है कर्ोंक्रक हाइिोलोक्जक
चि सौर ऊजाय द्वारा संचाललत होता है । (It is also an indirect form
of solar energy because hydrologic cycle is powered by solar
energy.)
• निी में बहने वाले पानी को बााँध ननमायण से एक बड़े जलािर् में
इकट्ठा का ललर्ा जाता है तथा इसे एक ऊंचाई से ननचे धगरार्ा
जाता है I बााँध के ननचले भाग में लगे टरबाइन के पंखे इस तेज़
पानी के बहाव से गनत में आ जाते हैं I
• इसमें ऊंचाई के कारण पानी में संग्रहीत संभाषवत ऊजाय (बांध के
पीछे जलािर् में संग्रहीत पानी) को टरबाइन की गनतिील ऊजाय में
पररवनतयत क्रकर्ा जाता है , क्जसे जनरे टर द्वारा षवद्र्तु ऊजाय में
पररवनतयत क्रकर्ा जाता है । (In this the potential energy stored in
water due to height (water stored in reservoir behind the dam) is
transformed into kinetic energy of turbine, which is then
tranformed to electrical energy by the generator).
• बबजली उत्पािन में क्रकसी भी अन्र् ऊजाय स्रोत की तल ु ना में र्ह
अधधक कुिल है - लगभग 90% उपलब्ध जल षवद्र्त ु ऊजाय को
बबजली में पररवनतयत कर हिर्ा जाता है । (It is more efficient than
any other energy source in producing electricity – about 90% of
available hydropower energy is converted into electricity.)
• र्ह सौर ऊजाय का सबसे व्र्ापक रूप से इस्तेमाल क्रकर्ा जाने वाला
रूप है । कनाडा, अमेररका, ब्राजील, चीन, रूस, नॉवे, जापान, भारत,
स्वीडन और फ्ांस में सबसे बड़े जलषवद्र्त ु उत्पािन वाले िस राष्ट्ट्र
हैं । (It is the most widely used form of solar energy. Ten countires
with greatest hydroelectric production are Canada, US, Brazil,
China, Russia, Norway, Japan, India, Sweden, and France.)
• Dam building have both advantages and disadvantages (already
discussed).
• बांध ननमायण गंभीर पाररक्स्थनतक और सामाक्जक प्रभावों से जुड़ा
हुआ है , इसललए नए और बड़े बांधों का ननमायण सीलमत होना
चाहहए। इसके ललए नए तकनीकी नवाचारों की आवश्र्कता है जो
छोटे बांधों से जलषवद्र्त ु के उत्पािन को बढ़ा सकें। Dam buildling
is also associated with serious ecological and social impacts,
construction of new and big dams should be limited. For this new
technological innovations are needed that can increase the
hydroelectric generation from small dams.
Ocean Thermal Energy
• उष्ट्णकहटबंधीर् महासागरों की सतह पर और गहरे स्तर पर पानी के
तापमान के बीच अंतर के कारण उपलब्ध ऊजाय को महासागरीर्
ताप ऊजाय कहा जाता है I (The energy available due to the difference
between temperature of water at surface of the tropical oceans and
at deeper levels is called Ocean Thermal Energy)
• सतह और गहरे पानी के बीच 20°C र्ा उससे अधधक का अंतर
आवश्र्क है । गमय सतह का पानी अमोननर्ा जैसे द्रव को उबालने के
ललए प्रर्ोग क्रकर्ा जाता है , और अमोननर्ा के उच्च िबाव वाष्ट्पों का
उपर्ोग तब टरबाइन को चालू करने के ललए क्रकर्ा जाता है और
जनरे टर बबजली उत्पन्न करता है । ठं डा गहरा पानी वाष्ट्पों को ठं डा
करने के ललए पंप क्रकर्ा जाता है । (A difference of 20°C or more is
needed between surface and deep waters. The warm surface water
is used to boil a liquid like ammonia, and high pressure vapours of
ammonia are then used to turn the turbine and, generator
produces electricity. The colder deep water is pumped to cool down
and condense vapors. This is also called OTEC ie. Ocean Thermal
Energy Conversion)
• पहला ओटीईसी प्लांट, हवाई द्वीप में ननमायणाधीन है । (First OTEC is
under construction in Hawaii island.)
अन्र् अनवीकरणीर् ऊजाय स्रोत: भ-ू तापीर् ऊजाय (Other
renewable energy sources: Geothermal Energy)

• भ-ू तापीर् ऊजाय, पथ्

ृ वी के भीतर की प्राकृनतक गमी होती
है, इसकी उत्पषि,
– पथ्ृ वी के core के भीतर प्राचीन गमी से,
– महाद्वीपीर् प्लेटों के एक-िस ू रे पर स्लाइड करने से
उत्पन्न घियण से, और
– रे ड्रडर्ोधमी तत्वों के क्षर् से होती है I
• Geothermal energy, is the natural heat within Earth,
arises from
– the ancient heat within Earth’s core,
– from friction where continental plates slide over one
another, and
– From the decay of radioactive elements.
• As groundwater in these areas travels downward
and is heated, it becomes buoyant and rises until
it is trapped by an impermeable layer in Earth’s
crust, forming a hydrothermal reservoir.
• Hydrothermal reservoirs contain hot water and
possibly steam, depending on the temperature
and pressure of the fluid. Some of the hot water
or steam may escape to the surface, creating hot
springs or geysers. E.g. in Manali, Kullu, Sohana
• Hydrothermal reservoirs are tapped by drilling
wells similar to those used for extracting oil and
natural gas.
• In USA, and New Zealand, several geothermal
plants are working.
Geothermal energy
Tidal energy
• ज्वार, समुद्र के सतह के पानी के बारी-बारी से, उत्थान और पतन को कहते हैं, र्े
आम तौर पर हर हिन िो बार होता है , और र्े चंद्रमा और सूर्य के गुरुत्वाकियण
खींच का पररणाम होता है । (Tides, the alternate rising and falling of the surface
waters of the ocean and seas that generally occur twice each day, are the result of
the gravitational pull of the moon and the sun. )
• आम तौर पर, उच्च और ननम्न ज्वारों के बीच पानी के स्तर में अंतर लगभग 0.5
मीटर (1-2 फीट) होता है । संकीणय खाड़ी वाले कुछ तटीर् क्षेत्रों में उच्च और ननम्न
ज्वारों के बीच पानी के स्तर में बहुत बड़ा अंतर होता है । बे ऑफ़ फंडी, कनाडा में
िनु नर्ा का सबसे बडा ज्वार है , क्जसमें उच्च और ननम्न ज्वारों के बीच 16 मीटर
(53 फीट) तक का अंतर है । (Normally, the difference in water level between high
and low tides is about 0.5 m (1–2 ft). Certain coastal regions with narrow bays
have extremely large differences in water level between high and low tides. The
Bay of Fundy, Canada has the largest tides in the world, with a difference of up to
16 m (53 ft) between high and low tides.)
• उच्च ज्वार पर पानी में कम ज्वार की तल ु ना में संभाषवत ऊजाय की भारी मात्रा
होती है । र्ह ऊजाय कैि की जाती है (एक बााँध और टरबाइन के साथ) और बबजली
में पररवनतयत हो जाती है । (Water at high tide contains enormous amounts of
potential energy as compared to low tide. This energy is captured (with a dam
across a bay and a turbine) and converted into electricity.)
• ज्वारीर् बबजली संर्ंत्र वतयमान में फ्ांस , रूस, चीन और कनाडा में काम करते हैं।
भारत में भी, र्ह कंबे की खाड़ी, कच्छ की खाड़ी, और संि ु रबान डेल्टा में काम कर
रहा है । (Tidal power plants currently operate in France, Russia, China, and Canada.
In India also, it is working at Gulf of Cambay, Gulf of Kutchh, and Sunderban deltas.
)
Water stored in Reservoir
During High tide

Reservoir
Low tide
turbine
Tidal barrage

High tide
Hydrogen & Fuel Cells
• Hydrogen is a common element—water molecules contain two hydrogen
atoms and one oxygen atom. While water contains little available chemical
energy, a hydrogen molecule with two hydrogen atoms (H2) contains large
amounts of available energy.
• H2, which is a gas at room temperature, will explode when combined with
the plentiful O2 in the atmosphere, releasing energy (150 kJ per g) and
forming water. When chilled to 253°C, H2 becomes a liquid and thus takes
up much less space than H2 gas.
• Hydrogen has both advantages and disadvantages as an energy source.
• Advantages:
– it has very high energy density, so hydrogen could substitute for gasoline in
automobiles and other forms of transportation.
– Relatively cleaner fuel: Electrolysis is the process of using electricity to
separate water into O2 and H2, which can be separately captured and stored.
Finally, when H2 is burned with O2, the two products are available energy and
water—no greenhouse gases and no other pollutants except for relatively
small amounts of oxides of nitrogen.
• Disadvantages:
– Its extreme volatility means that it has to be stored,
handled, and transported very carefully.
– the process of converting water into hydrogen is very
inefficient, so only a fraction of the energy from
electricity can be captured when the hydrogen is
burned.
– Since our main sources of electricity continue to be
coal, natural gas, hydropower, and nuclear energy,
producing hydrogen from this electricity will still
create all the environmental problems associated with
those sources.
 Hydrogen fuel cell
• The most promising
way to use hydrogen
is in a fuel cell. A fuel
cell is an
electrochemical cell
similar to a battery.
• Fuel cell reactants
(hydrogen and
oxygen) are supplied
from external
reservoirs. When
hydrogen and oxygen
react in a fuel cell,
water forms and
energy is produced as
an electric current.
• Uses:
– Presently, Liquid H2 is used as a fuel in spaceships
– H-fuel cells are used to generate electricity
– Hydrogen fuel cell vehicles (HFCVs) are now being
used in some countries like US.
– Iceland plans to build the world’s first fleet of fuel
cell buses, obtaining its hydrogen fuel by using
existing geothermal and hydroelectric resources.
 Fossil Fuels
• A fossil fuel is composed of the remnants of dead
organisms, that got buried and compressed in an
oxygen-deficient environment for millions of years, and
got converted to coal, oil or natural gas.
• Coal: Coal is found in different grades, largely as a
result of the varying amounts of heat and pressure it
was exposed to during formation.
– Lignite,
– Sub-bituminous coal,
– bituminous coal, and
– anthracite
• Coal, the most abundant fossil fuel in the world, is
found primarily in the Northern Hemisphere.
• The largest coal deposits are in the United States,
Russia, China, Australia, India, Germany, and South
Africa.
• world coal reserves could last more than 200 years at
the present rate of consumption but if its use rate
increases by 2%per year, it will last for only 65 years
• India has world’s 5% coal reserves, its not of high
grade. Coal states in India are Jharkhand, Odisha, W.
Bengal, MP, AP, Maharashtra. Anthracite occurs only in
J&K.
Environmental impacts of burning coal:
• Burning coal can affect air and water quality, and impacts range from local
(for example,
• sooty fallout) to global (climate change and ocean acidification).
• Coal burning generally contributes more air pollutants (including CO2)
than does burning either oil
• or natural gas to generate the same amount of useful energy.
• Coal often contains mercury that is released into the atmosphere during
combustion. This mercury moves readily from the atmosphere to water
and land, where it accumulates and harms humans
• as well as wildlife.
• Much bituminous coal contains sulfur and nitrogen that, when burned, are
released into the atmosphere as sulfur oxides (SO2 and SO3) and nitrogen
oxides (NO, NO2, and N2O). Sulfur oxides and the nitrogen oxides NO and
NO2 form acids when they react with water. These reactions result in acid
deposition..
Petroleum
• Petroleum, or crude oil, is a liquid composed of hundreds of hydrocarbon
compounds. During petroleum refining, the compounds are separated into
different products—such as gases, gasoline, heating oil, diesel oil, and
asphalt—based on their different boiling points
• Oil is also used to produce petrochemicals, compounds in such diverse
products as fertilizers, plastics, paints, pesticides, medicines, and synthetic
fibers.
• It used to make LPG for domestic use.
• It burns cleaner than coal.
• Oil reserves distribution is uneven, and a large portion of total oil deposits
are clustered relatively close together. Enormous oil fields containing more
than half of the world’s total estimated reserves are situated in the Persian
Gulf region, which includes Iran, Iraq, Kuwait, Oman, Qatar, Saudi Arabia,
Syria, the United Arab Emirates, and Yemen. In addition, major oil fields
are known to exist in Venezuela, Mexico, Russia, Kazakhstan, Libya, and
the United States (in Alaska and the Gulf of Mexico). In India, oil fields are
in Digboi (Assam), Gujarat plains and Bombay high, offshore areas in
deltaic coasts of Godavrari, Krishna, Cauvery, and Mahanadi
• At present rate of use, these reserves are expected to exhaust in another
40yrs.
Natural Gas
• It is mainly composed of methane (95%) with
small amounts of propane and ethane.
• It’s a clean fuel.
• Major reserves of natural gas are located in two
countries, Russia (40%), Iran (14%) and US (7%).
• In India, NG reserves are associated with oil
fields, and also in Tripura, Jaisalmer,, off-shore
area of Mumbai and the Krishna – Godavari delta.