Energy and Power Resources | ICSE Class 7 Geography Notes

This note covers energy sources, renewable and non-renewable resources, solar power, wind power, hydroelectricity, major Indian hydroelectric projects, coal, petroleum, access to energy, and conservation at home and in school.

What are energy and power resources, and why do we need them?

Energy is the capacity to do work. In everyday life, it is needed for cooking, lighting, heating, moving vehicles and running machines. An energy resource is a source from which useful energy can be obtained.

Power means the rate of doing work. In discussions of power resources, the word also commonly refers to the supply of electricity. Electricity is a form of energy that can be produced using different resources.

How do resources support development?

Agriculture, industry, transport and homes all need energy. Factories require energy to operate machinery; vehicles require energy to move. Energy resources therefore help an area develop by supporting both production and everyday activities.

The important question is not simply whether electricity is available. We must also ask which resource supplies it. Electricity produced using coal depends on a different natural resource from electricity produced using flowing water.

What should we ask about a source?

Study each source through its origin, uses and effects. Ask whether it is renewed naturally, how it supplies useful energy, where it occurs, and what problems accompany its use. This connects physical geography with people's needs.

Conservation means using resources carefully and avoiding waste. Meeting energy needs and conserving resources belong together: a supply that supports present activities must also be considered in relation to future needs.

How do renewable and non-renewable energy resources differ?

Renewable resources are resources renewed by natural processes. Sunlight, wind and flowing water provide renewable energy. Non-renewable resources have limited stocks that are not replaced on the timescale of human use. Coal and petroleum belong to this group.

Why is the rate of replacement important?

Coal formation takes millions of years. Using a coal deposit reduces a stock that cannot be rapidly restored. The existence of natural processes that originally formed coal does not make coal renewable for our everyday needs.

Water is different. The water cycle is the continuing movement of water through the environment. Water moves continually through this cycle, renewing supplies that are used as a resource. It is not a stock permanently used up by passing through a turbine.

Does renewable mean available everywhere?

No. Water availability varies from place to place and with seasons and rainfall. Likewise, a source being renewable does not establish that every location is equally suitable for using it. Resource planning must consider local conditions.

Note: Renewable and non-conventional are different classifications. Hydroelectricity uses renewable water, but it is included among conventional energy sources. Conventional means long-established in use; non-conventional refers to alternative sources such as solar and wind energy.

The key distinction is renewability, meaning whether a resource is naturally renewed on a useful timescale. Do not classify a source simply by whether its equipment looks modern or whether it produces electricity.

How does solar power provide useful energy?

Solar energy is energy received from the Sun. Solar power uses this energy for useful purposes. Photovoltaic technology converts sunlight directly into electricity. A solar cell is a device that carries out this conversion.

What is the source and what is the equipment?

Sunlight is the energy source; the solar cell is the equipment used to obtain electricity from it. Keeping the source and the device separate makes classification easier. A manufactured device can use a naturally renewed energy supply.

Solar cells grouped together form a solar panel. A panel does not need flowing river water to perform its conversion. Its useful input is sunlight, so the availability of sunlight matters when considering its use.

Direct solar electricity generation requires sunlight. It does not take place in darkness, and cloud cover can reduce output. These limitations concern the availability of the input; they do not change solar energy's classification as renewable.

Why is solar energy important in India?

India has enormous possibilities for using solar energy. It is fast becoming popular in rural and remote areas. Rural means relating to villages and the countryside; remote places are those far from major centres.

Solar power can reduce dependence on firewood and dried dung cakes used as fuel. Reducing the burning of dung also leaves more material available as manure, which is added to soil to improve its fertility.

This links energy choices with environmental conservation and agriculture. A solar supply can meet an energy need while helping reduce pressure on other resources. Its importance is therefore broader than the equipment used to generate electricity.

Rajasthan is well endowed with solar and wind energy but lacks water resources. This example shows why choosing a resource requires attention to the particular strengths and limitations of a region.

How is wind used to generate power?

Wind is moving air. A wind turbine is a machine whose blades are turned by wind. Its rotation drives a generator, a device that converts mechanical movement into electrical energy.

What happens during generation?

The moving air supplies the energy, the blades rotate, and the connected generator produces electricity. The machine uses the motion of air rather than burning a stock of coal or petroleum. Wind is naturally renewed, so wind energy is classed as renewable.

A wind farm is a group of wind turbines in an area used for generating electricity. The name refers to a collection of generating machines, not to a farm growing a crop.

Wind conditions matter. A turbine needs suitable wind to operate, and its output varies as the wind changes. A place having some wind does not by itself establish that it is equally suitable for a wind farm.

Case study: Where is wind energy used in India?

Tamil Nadu has wind farms in the area from Nagarcoil to Madurai. Andhra Pradesh, Karnataka, Gujarat, Kerala, Maharashtra and Lakshadweep also have important wind farms. Nagarcoil and Jaisalmer are known for effective use of wind energy.

These locations show that the geography of a resource matters. Learning a place name is more useful when it is connected to the energy source used there. Jaisalmer, for example, belongs with the study of wind energy.

How does wind power compare with solar power?

Both use renewable sources, but their inputs differ. Solar cells use sunlight; wind turbines use moving air. Their equipment and immediate method of producing electricity are different even though both help diversify energy supply.

Diversifying supply means using more than one energy source. Increased use of renewable sources, together with conservation, helps reduce dependence on limited fossil-fuel resources.

How does flowing water produce hydroelectricity?

Hydroelectricity, also called hydel power, is electricity generated using moving water. Fast-flowing water drives a hydro turbine, a rotating machine designed to obtain energy from water. The turbine drives a generator to produce electricity.

What is the role of a dam?

A dam is a barrier built across flowing water to obstruct or control its flow. It often creates a reservoir, a body of stored water. A dam and its reservoir are related but distinct parts of a river project.

In a dam-based hydroelectric project, stored water can be released through a route leading to the turbines. The following sequence explains the basic connection between water storage and electricity generation.

1. Water collects in the reservoir behind the dam.
2. Water is released and flows through a passage towards a turbine.
3. The force of the moving water turns the turbine.
4. The turbine drives a generator, which produces electricity.
5. Water leaving the turbine continues downstream, meaning farther along the river's direction of flow.

Why is hydroelectricity renewable?

The water cycle continually renews water. The project uses water's movement to generate electricity rather than using up a stock of fossil fuel. Fossil fuels are fuels formed from the remains of ancient living organisms over very long periods.

Renewability does not mean unlimited water at every time. River flow and water availability vary. A hydroelectric project must be considered together with the water needs and environmental conditions of its river basin, the area drained by a river and the smaller streams that join it.

How does it differ from thermal electricity?

Thermal electricity is generated using heat, including heat obtained by burning fuels such as coal and petroleum. Hydroelectricity uses moving water. Once generated, the electricity is the same; the distinction lies in the resource and generation process.

This distinction helps explain conservation. Switching off an unnecessary light saves electricity regardless of its source, while the consequences for particular natural resources depend on how that electricity was generated.

Which Indian hydroelectric projects should we locate on a map?

A hydroelectric project should be learnt as a connected set: its name, its river and its state. Location matters because a project depends on a particular river system. Remembering an isolated dam name does not identify its geographical setting.

How do project names connect with rivers and states?

The Bhakra-Nangal entry contains two linked names. Keep the location of each dam clear rather than assigning both structures to one state. The wider river basin and the position of an individual structure are not identical descriptions.

The Bhakra-Nangal project uses water for both hydroelectric generation and irrigation. Irrigation means supplying water to crops. A multipurpose project combines several uses of river water, rather than serving a single purpose.

How should we read the river map?

Rivers appear as blue lines and dam locations as dark dots. The map labels Bhakra Nangal by the Sutluj, Tehri by the Bhagirathi, Hirakud by the Mahanadi, Sardar Sarovar by the Narmada, and Tungabhadra by the river of the same name.

Reference: NCERT Class 10, printed page 24

On an outline map, first identify the river and then place the project along it. Add the project name clearly. Use the table to connect each location with its state, keeping river labels distinct from project labels.

A map key explains what symbols stand for. When making a practice map, use one consistent symbol for dams and explain it in a key. Do not confuse a river line with a state boundary.

Notice the spread of projects across different river systems. Their distribution gives a geographical picture of water use, while the table supplies the precise name-river-state combinations needed to describe each location.

What benefits and problems can large river projects create?

Large river projects connect electricity generation with other uses of water. A multipurpose dam may support irrigation, water supply, flood control, recreation, movement of boats within the country and fish breeding. Its importance therefore extends beyond electricity alone.

What benefits can stored water provide?

The Bhakra-Nangal project combines hydel power production with irrigation. Hirakud, in the Mahanadi basin, connects water conservation with flood control. These examples show how one river project can serve more than one need.

Flood control means managing water to reduce flooding. It should not be understood as a promise that floods cannot occur. Big dams have mostly been unsuccessful in controlling floods at the time of excessive rainfall.

Case study: What irrigation benefits are planned for Sardar Sarovar?

The Sardar Sarovar project on the Narmada in Gujarat covers four states: Maharashtra, Madhya Pradesh, Gujarat and Rajasthan. Its planned irrigation coverage shows how a river project can supply water beyond the state where its dam stands.

How can rivers and people be affected?

Damming changes a river's natural flow. It also affects sediment, the particles of material carried by water. Sediment can accumulate in a reservoir, while less material continues along the river below it.

This can produce rockier riverbeds and poorer habitats for aquatic life. Aquatic life means organisms living in water. Dams break up the continuity of rivers and make movement difficult for aquatic animals, especially during breeding.

Reservoirs can submerge existing vegetation and soil. Large multipurpose projects can also cause displacement, meaning that people have to leave the places where they live, and loss of livelihoods, the activities through which they earn a living.

These concerns do not change hydroelectricity's renewable classification. They show why renewable does not mean free of environmental or social effects. A balanced assessment considers electricity and water benefits alongside effects on rivers, land and people.

Why is coal an important non-renewable energy resource?

Coal is a solid fossil fuel formed from plant material compressed over millions of years. It supplies energy for electricity generation, industry and domestic needs. Its formation is far too slow to replace what people consume during everyday use.

Why do different kinds of coal occur?

The nature of coal depends on compression, depth and time of burial. Lignite is a low-grade brown coal that is soft and has high moisture content. Bituminous coal is the most popular coal in commercial use. Anthracite is the highest-quality hard coal.

Neyveli in Tamil Nadu has the principal lignite reserves used for electricity generation. Jharia, Raniganj and Bokaro are important coalfields. A coalfield is an area containing coal deposits. These names link the resource to its geographical distribution.

Indian coal deposits occur in rock series of two main geological ages. These ages show the long timescale involved, helping explain why coal is a non-renewable resource.

Why does location matter to industry?

Coal is bulky and loses weight when used because it is reduced to ash. Heavy industries and thermal power stations are therefore located on or near coalfields. This connects the distribution of a fuel with the location of activities using it.

Coal mining also creates risks. Dust and harmful fumes threaten miners' health. Collapsing mine roofs, fires and flooding are dangers. Mining waste can damage land and pollute water, so obtaining the resource has consequences before it is burned.

How can the fossil-fuel map be read?

The key uses triangles for coal mines and red squares for oilfields. Jharia, Bokaro and Raniganj are labelled in the eastern coal region; Mumbai High appears offshore west of India. Natural gas is another fossil fuel shown on this map.

Reference: NCERT Class 10, printed page 51

Offshore means situated in the sea away from the coast. Read the map key before identifying a resource: a location marked as an oilfield should not be described as a coal mine.

How is petroleum used, and why must it be conserved?

Petroleum, also called mineral oil, is a liquid fossil-fuel resource. It supplies fuels for heat and lighting, lubricants for machinery, and raw materials for manufacturing. Lubricants are substances used to reduce friction between moving surfaces.

Why is petroleum important beyond fuel?

A refinery is an industrial plant that processes crude petroleum into useful products. Crude petroleum means petroleum before refining. Petroleum refineries support synthetic textile, fertiliser and chemical industries by supplying materials used in production.

Synthetic textiles are textiles made from manufactured fibres. A fertiliser supplies nutrients used by plants. These uses show that petroleum matters not just as a fuel but also as a starting material for other products.

This makes conservation relevant to more than transport or lighting. Careful use of petroleum protects a limited resource that supports several kinds of economic activity. Its many uses do not make its supply renewable.

Where does petroleum occur in India?

Mumbai High, Gujarat and Assam are major petroleum-producing areas. Mumbai High is an offshore location. Digboi, Naharkatiya and Moran-Hugrijan are important oilfields in Assam. Gujarat also contains important oilfields.

The geography of oil differs from that of coal. Learn the symbols and place names for each separately. The fossil-fuel map allows both resources to be compared without treating all marked locations as the same kind of deposit.

Why reduce dependence on fossil fuels?

Increasing use of fossil fuels causes serious environmental problems. Possible shortages also create uncertainty about future energy supply. Conservation and greater use of renewable sources address these concerns together.

Dependence means relying on something to meet a need. Reducing dependence on petroleum does not mean that its present uses disappear. It means using the resource carefully and developing other sources where they can meet energy requirements.

How should we study access to energy among different groups?

Energy access means people's ability to obtain useful energy for their needs. Energy consumption means the energy they use. These are connected ideas, but identifying a resource in a region does not by itself describe every household's access.

What does fair distribution involve?

Equitable distribution means fair access to resources. Resources concentrated in a few hands can divide society into those who have them and those who do not. Resource planning should consider people's needs alongside the physical availability of resources.

A region may possess resources but lack the technology or supporting facilities needed to use them fully. These supporting facilities are called infrastructure. Thus, a map of coalfields or rivers alone cannot explain every difference in development.

How can a local survey help?

A survey gathers information systematically through observations or questions. An energy survey can compare uses at home and school, or investigate differences between rural and urban areas. Urban means relating to towns and cities.

• Identify the sources used for cooking, lighting and other activities.
• Ask which activities depend on electricity and which use fuels directly.
• Record actual electricity consumption over a stated period.
• Look for avoidable use, such as lights operating when they are not needed.
• Suggest measures that fit the uses actually observed.

Rural electrification means extending electricity supply to rural areas. Studying it involves considering who receives a supply and how it is used. Do not assume that all villages, or all households within one village, have identical circumstances.

A useful comparison states what was observed, where it was observed and the period covered. A single household's experience is not evidence for every household. Base conclusions on collected information rather than stereotypes about rural or urban life.

How can we conserve energy at home, in school and while travelling?

Energy conservation means careful use of energy resources and reduction of waste. It matters because fossil-fuel stocks are limited, energy supports development, and energy use affects the environment. Conservation is a practical part of daily life.

Which actions reduce unnecessary consumption?

Switch off lights, fans and air conditioners when they are not needed. An air conditioner is equipment used to cool indoor air. Use power-saving devices and avoid leaving equipment running without a useful purpose.

Use public transport instead of individual vehicles where possible. Public transport carries people in shared services. Increased use of renewable energy sources is another part of conserving limited energy resources.

Energy efficiency means providing a useful service with less energy. Conservation includes avoiding an unnecessary use altogether, while efficiency focuses on reducing the energy required for the service. Both support careful resource use.

How can observation become action?

1. List the activities that use energy at home or in school.
2. Observe which lights, fans or other devices operate unnecessarily.
3. Record electricity consumption over a period using actual readings or bills.
4. Choose conservation measures suited to the unnecessary uses identified.
5. Continue recording consumption and compare the results over clearly stated periods.

When showing results on a graph, put the time period along the horizontal direction and consumption along the vertical direction. Label the measure exactly as recorded. A graph should represent collected data; invented readings cannot show actual savings.

What makes energy use sustainable?

Sustainable development meets present needs without damaging the environment or compromising future generations' needs. Energy conservation and increased use of renewable resources are complementary ways of working towards it.

Saving energy does not require abandoning useful activities. It requires recognising waste, choosing suitable equipment and using resources thoughtfully. The purpose is to support people's needs while reducing unnecessary pressure on resources.

A complete approach therefore links individual habits with wider planning: careful use at home and school, suitable energy sources, fair access, and attention to the environmental and social effects of energy projects.

Glossary

• Energy — The capacity to do work, needed for activities such as cooking, lighting and running machinery.
• Power — The rate of doing work; the word also commonly refers to electricity supply.
• Renewable resource — A resource renewed by natural processes, such as sunlight, wind or flowing water.
• Non-renewable resource — A resource with limited stocks that are not replaced on the timescale of human use.
• Fossil fuel — Fuel formed from ancient living organisms over very long periods, including coal and petroleum.
• Photovoltaic technology — Technology that converts sunlight directly into electricity through devices called solar cells.
• Wind farm — A group of wind turbines used to generate electricity from the movement of air.
• Hydroelectricity — Electricity produced using moving water to turn turbines connected to generators.
• Reservoir — A body of stored water, often created behind a dam across a river.
• Multipurpose project — A river project combining several uses, such as electricity generation, irrigation and water supply.
• Refinery — An industrial plant where crude petroleum is processed to obtain useful products.
• Displacement — The movement of people who have to leave the places where they live.
• Conservation — Careful use of resources and reduction of waste to protect supplies for future needs.
• Sustainable development — Development that meets present needs without damaging the environment or compromising future generations' needs.

Common errors and misconceptions

• Misconception: All electricity comes from coal. Correct: Electricity can be generated from different resources, including flowing water, sunlight and wind. Identify the source used for generation.
• Misconception: Coal is renewable because natural processes formed it. Correct: Coal takes millions of years to form and is not replaced on the timescale of human use.
• Misconception: Renewable resources are equally available everywhere. Correct: Conditions differ between regions, and water availability also varies with seasons and rainfall.
• Misconception: Renewable hydroelectricity has no environmental effects. Correct: Dams can alter river flow, interrupt aquatic animals' movement and submerge vegetation and soil.
• Misconception: A multipurpose project serves electricity generation alone. Correct: It combines uses of water, which may include irrigation, water supply and flood management.
• Misconception: A dam's location and every area benefiting from its project are the same. Correct: Identify the structure's river and state separately from the wider uses of the project.
• Misconception: Conservation means stopping useful energy use. Correct: It means careful use and reducing waste, alongside efficient equipment and suitable renewable sources.

Exam-style questions with model answers

Q1. Coal takes millions of years to form, while flowing water is renewed through the water cycle. Classify each source as renewable or non-renewable and give the reason. [2 marks]

1. Coal is non-renewable because its formation takes millions of years, so it cannot be replaced on the timescale of human use.
2. Flowing water is renewable because the continuing water cycle renews the water supply.

Q2. Photovoltaic technology converts sunlight directly into electricity. Wind turns turbine blades connected to a generator. Give two differences between these methods, comparing their energy inputs and equipment. [2 marks]

1. Solar generation uses sunlight as its input, whereas wind generation uses moving air.
2. Solar generation uses photovoltaic equipment, whereas wind generation uses rotating turbine blades connected to a generator.

Q3. In a hydroelectric project, water collects behind a dam, flows through a passage to a turbine, turns it, and drives a connected generator. Explain electricity generation in four ordered steps. [4 marks]

1. Water first collects in the reservoir behind the dam, providing the stored water used by this hydroelectric project.
2. Water is then released through a passage towards the turbine, so it moves from storage into the generating system.
3. The moving water turns the turbine, transferring energy from the water's motion to the rotating machine.
4. The turbine drives the connected generator, which converts the mechanical movement into electrical energy.

Q4. Tehri is on the Bhagirathi in Uttarakhand; Hirakud is on the Mahanadi in Odisha; Sardar Sarovar is on the Narmada in Gujarat. Write one complete project-river-state identification for each project. [3 marks]

1. Tehri belongs with the Bhagirathi River and Uttarakhand. These identify its river and state location respectively.
2. Hirakud belongs with the Mahanadi River and Odisha. These identify its river and state location respectively.
3. Sardar Sarovar belongs with the Narmada River and Gujarat. These identify its river and state location respectively.

Q5. Large dams can use moving water to generate electricity and provide irrigation, supplying water to crops. They also alter river flow, trap sediment, submerge vegetation and soil, and displace people, making them leave their homes. Using these facts, explain two benefits and four concerns in six separate points. [6 marks]

1. Electricity generation is a benefit because the project uses the movement of water to supply useful electrical energy.
2. Irrigation is another benefit because water from the project can be supplied to crops, supporting agricultural activity.
3. Altered river flow is a concern because controlling water at the dam changes the river's natural movement.
4. Trapped sediment is a concern because material carried by the river accumulates in the reservoir rather than continuing downstream.
5. Submergence is an environmental concern because land covered by stored water includes existing vegetation and soil.
6. Displacement is a social concern because people affected by the project may have to leave the places where they live.

Q6. A conservation checklist recommends switching off unnecessary lights, switching off unnecessary fans and air conditioners, using power-saving devices to provide the same service with less energy, using shared public transport instead of individual vehicles, and increasing suitable renewable energy use to reduce dependence on limited fuels. Explain these five recommendations, one per point. [5 marks]

1. Switch off lights when they are not needed, avoiding electricity consumption that is not providing a useful lighting service.
2. Switch off fans and air conditioners when they are unnecessary, reducing avoidable energy use for moving or cooling air.
3. Choose power-saving devices so that useful activities can be performed with less energy, improving efficiency while meeting needs.
4. Use public transport instead of individual vehicles where possible because carrying many passengers together can use less fuel per passenger than separate private vehicles.
5. Increase the use of renewable energy where suitable, reducing dependence on limited non-renewable resources while continuing to meet energy needs.

Q7. Coal is bulky and becomes ash when used. Heavy industries and thermal power stations are located on or near coalfields. Mining dust and harmful fumes threaten health; waste can pollute water. Explain one location relationship and two mining concerns. [3 marks]

1. Heavy industries and thermal power stations are located on or near coalfields because coal is bulky and loses weight when burned to ash. Using it near the coalfields reduces the need to transport large quantities of coal over long distances.
2. Dust and harmful fumes create a health concern for miners because working with the resource can expose them to these materials.
3. Mining waste creates an environmental concern because it can enter or affect water sources, causing pollution in the surrounding region.

Q8. Petroleum supplies fuels for heat and lighting, lubricants for machinery, and raw materials for manufacturing. Lubricants reduce friction between moving surfaces. Explain these three uses, with one use in each point. [3 marks]

1. Petroleum supplies fuels used for heating and lighting, making it an energy resource that supports these useful everyday activities.
2. Petroleum provides lubricants for machinery. These substances reduce friction between moving surfaces, serving a purpose distinct from supplying fuel.
3. Petroleum supplies raw materials for manufacturing industries. It therefore supports the making of products as well as meeting energy needs.

Key takeaways

• Energy supports cooking, lighting, transport and industry, linking natural resources with daily life and development.
• Sunlight, wind and flowing water are renewable sources; coal and petroleum are limited non-renewable fossil fuels.
• Solar cells convert sunlight directly into electricity, while wind turbines obtain energy from moving air.
• Hydroelectricity uses flowing water to drive turbines and generators, with water renewed through the water cycle.
• Learn major hydroelectric projects with their rivers and states, then connect those identifications with map locations.
• Large dams can provide several benefits but also alter rivers, submerge land and affect people's lives.
• Fair access depends on more than resource deposits; technology, supporting facilities and people's needs also matter.
• Energy conservation combines avoiding waste, using efficient devices and increasing suitable renewable energy use.

Test yourself

Why does coal formation by a natural process not make coal renewable?

Coal takes millions of years to form, so natural formation cannot replace it on the timescale of human use.

What does photovoltaic technology do?

It converts sunlight directly into electricity, using devices called solar cells.

What input does a wind turbine use?

It uses moving air to turn blades, which drive a generator to produce electricity.

How are a dam and a reservoir different?

A dam is a barrier across flowing water; a reservoir is a body of stored water, often behind a dam.

Which river and state are associated with Hirakud?

Hirakud is on the Mahanadi River in the state of Odisha.

What makes a river project multipurpose?

It combines several uses of water, such as hydroelectric generation, irrigation and water supply.

Why is renewable hydroelectricity not necessarily free of environmental effects?

Dams can alter river flow, interrupt the movement of aquatic animals, and submerge vegetation and soil.

What are two practical actions for conserving energy?

Switch off electrical equipment when it is not needed and use power-saving devices for useful activities.