Non-Conventional Sources of Energy: NBSE Class 11 Environment

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Get notes, summary, questions and answers, MCQs, extras, and PDFs of Chapter 20 “Non-Conventional Sources of Energy” which is part of NBSE Class 11 Environment Education. However, the notes should only be treated as references and changes should be made according to the needs of the students.

Summary

Chapter 20 discusses non-conventional sources of energy, which are inexhaustible and renewable. These include solar energy, hydel energy, wind energy, geothermal energy, tidal energy, wave energy, biomass, and nuclear energy. Solar energy has the most potential, and it can be directly or indirectly harnessed. Solar cookers, solar water heaters, and solar cells are examples of how solar energy is used. Solar energy’s advantages include being clean, renewable, and abundant, though its limitations include variability and high costs.

Hydel energy is generated from running water, using dams and turbines to convert water flow into electricity. While hydel power is clean and renewable, large projects often lead to deforestation and displacement of communities. Smaller hydroelectric projects are more environmentally friendly and useful in remote areas.

Wind energy is generated using windmills, which convert wind into electricity. Large-scale wind farms are required for commercial electricity generation. Wind energy is pollution-free but depends on wind availability.

Geothermal energy comes from the Earth’s internal heat and is tapped by using steam from underground to run turbines. It is a stable energy source but is location-specific and expensive to harness.

Tidal and wave energy utilize the movement of water caused by tides and waves to generate electricity. These sources are renewable but have environmental challenges like disrupting aquatic life.

Biomass energy comes from organic materials like wood and agricultural waste. It can be burned to produce energy or converted into biofuels. Biomass is a renewable source but can be inefficient if transportation is required.

Nuclear energy is generated by splitting atoms, a process that releases vast amounts of energy. However, it produces harmful radioactive waste and can lead to catastrophic accidents.

Promoting non-conventional energy sources is crucial for reducing pollution and ensuring sustainable energy for the future. India has a significant potential to produce renewable energy.

Textbook solutions

Multiple-Choice Questions

1. Where is a pilot solar power plant of 50 kW installed in India?

A. Gurgaon, Haryana
B. Gurdaspur, Punjab
C. Panaji, Goa
D. Itanagar, Arunachal Pradesh

Answer: A. Gurgaon, Haryana

2. What kind of utensils are used to cook food in a solar cooker?

A. Plastic
B. Glassware
C. Metallic
D. Melamine

Answer: C. Metallic

3. A photovoltaic cell converts-

A. Chemical energy into heat energy
B. Light energy into electrical energy
C. Electrical energy into heat energy
D. Electrical energy into light energy

Answer: B. Light energy into electrical energy

4. Which country is the largest hydroelectricity producer?

A. India
B. China
C. Japan
D. Australia

Answer: B. China

5. The gravitational pull of the sun and moon is minimum on-

A. New moon day
B. Full moon day
C. Both (A) and (B)
D. None of the above

Answer: D. None of the above

Short Answer Questions

1. What is the difference between conventional and non-conventional sources of energy?

Answer:

• Conventional sources of energy are exhaustible, such as coal, petroleum, and natural gas.
• Non-conventional sources of energy are inexhaustible, such as solar energy, wind energy, and geothermal energy.

2. What is a solar cell?

Answer: A solar cell is a device that directly converts solar energy into electrical energy. It is also called a photovoltaic cell.

3. What is a wind farm?

Answer: A wind farm is a large area where a number of windmills are erected. The energy output from all the windmills is coupled together to generate electricity on a large scale.

4. What is geothermal energy?

Answer: Geothermal energy is the heat energy from hot rocks present inside the Earth. It can be harnessed for generating electricity by extracting steam from the ground, which drives turbines connected to generators.

5. What is ocean thermal energy?

Answer: Ocean thermal energy is the heat contained in ocean water heated by the sun. It can be converted into electricity by utilising the difference in temperature between the surface and the lower depths of the oceans.

6. What is a solar panel?

Answer: A solar panel is a group of solar cells connected in a specific pattern to produce a desired potential difference and magnitude of current.

7. What do you mean by hydel energy?

Answer: Hydel energy refers to the energy generated from running water, which is used to produce hydroelectricity by making water fall on turbines connected to generators.

8. Write a short note on the potential of India for renewable sources of energy.

Answer: India has a vast potential for renewable energy production. It is the third largest producer of electricity in the world. The important renewable energy sources utilised for generating electricity in India include wind power, solar power, biomass power, waste to power, and small hydropower. The potential capacities of these sources, as of 31st March 2017, are:

• Wind Power: 32,279.77 MW
• Solar Power: 12,288.83 MW
• Biomass Power: 8,182.00 MW
• Waste to Power: 114.08 MW
• Small Hydropower: 4,379.85 MW

Long Answer Questions

1. Explain the working of a photovoltaic cell.

Answer: A device which directly converts solar energy into electrical energy is called a solar cell. The solar cell is also called a photovoltaic cell. The term “photo” stands for light and “voltaic” stands for the generation of potential difference. Thus, a photovoltaic cell is a device which converts light energy into electrical energy, due to the generation of potential difference.

2. What are the disadvantages of wind energy?

Answer:

• Windmills create noise pollution and are required to be installed at least 500 m away from the nearest residential area.
• Energy generation depends upon the direction and velocity of wind, which is variable and irregular.
• Wind turbines can interfere with telecommunications and aeroplanes. They should be located away from airports, telecommunication towers, etc.

3. What is biogas? Explain the types of biogas plants.

Answer: Biogas refers to a mixture of gases like methane, carbon dioxide, hydrogen, and hydrogen sulphide produced during the decomposition of organic matter, such as animal dung, human excreta, and agricultural waste, in the absence of air. Biogas is a good fuel for cooking and lighting. The residue left after the removal of biogas is a good source of manure.

The two types of biogas plants commonly used are: (i) Fixed dome type biogas plant (ii) Floating gas holder type biogas plant

4. Explain the working of a hydroelectric plant.

Answer: Water is collected at a certain height in huge reservoirs. This water, which has a lot of potential energy, is made to fall on turbines connected to huge generators, which generate electricity. The falling water drives a turbine whose revolving shaft is connected to a generator. As the turbine rotates, the generator converts mechanical energy into electrical energy.

5. Explain the extraction energy from geological regions of the Earth.

Answer:

• In some geological regions of the Earth, the underground water comes in contact with hot spots and changes into steam. The steam so formed gets trapped in between the underground rocks and gets compressed to very high pressure. This steam is extracted from the ground by sinking pipes from the surface of the Earth. The steam coming up at high pressure is used in running turbines connected to the generator, producing electrical energy.
• In some places, the steam formed under the surface of the Earth does not get trapped. Instead, it forces its way up through the cracks in the rocks along with hot water and gushes out from the surface of Earth to form natural geysers. The heat energy brought up by the natural geysers is used to generate electricity as stated above.
• In some geological regions of the Earth, there may be hot spots, but the underground water does not come in contact with them. In such regions, two holes are made in the Earth’s crust. Through one hole, cold water is pumped in. The cold water on coming in contact with the hot spot changes to super-heated steam, which emerges out from the other hole. The steam is then made to run a turbine coupled with a generator to produce electricity.

6. Explain nuclear energy and its limitations.

Answer: The energy that binds the nucleus of an atom together is enormous. By releasing the energy from the nuclei of millions of atoms, nuclear power stations can generate a huge amount of power. Nuclear fission releases energy by splitting the nuclei of heavy radioactive metals like uranium. In nuclear fusion, energy is released by fusing together small atoms such as deuterium.

Limitations of Nuclear Energy:

• There is a possibility of an accident in a nuclear power plant. The accident at Three Mile Island nuclear power plant in the USA in March 1979, the explosion at Chernobyl power plant in Ukraine (a part of erstwhile USSR) and the Fukashima Daiichi nuclear disaster in Japan on March 11, 2011, have turned the attention of people towards the harmful effects of nuclear energy.
• Another harmful effect of the nuclear reactors is the generation of radioactive wastes. It takes thousands to millions of years for most of these materials to lose their radioactivity. However, we do not as yet know how to handle and dispose of these wastes safely.

Think and Answer

1. Why do solar energy have great potential in our country?

Answer: Solar energy has great potential in our country because India receives about 6,000 billion MW of solar energy per year. If only one per cent of this energy could be tapped at even 10 per cent efficiency, it would be 30 to 35 times India’s present electricity generation.

2. Reema thinks that disadvantages of a nuclear plant far outweigh its advantages. Is she right or wrong in your opinion? Give reasons for your answer.

Answer: Reema is right because nuclear plants pose the possibility of accidents. The accidents at Three Mile Island, Chernobyl, and Fukushima have highlighted the harmful effects of nuclear energy. Additionally, nuclear reactors generate radioactive wastes, which take thousands to millions of years to lose their radioactivity, and we do not yet know how to handle and dispose of these wastes safely.

3. Do you think mega projects such as large dams are a viable option for a developing country like India? Explain if you disagree, what alternatives would you suggest.

Answer: Mega projects such as large dams are not a viable option for a developing country like India because they lead to environmental problems such as deforestation, submergence of villages, and displacement of people. Alternatives like small hydroelectric projects and non-conventional sources of energy such as solar, wind, and biomass should be considered, as they are more environment-friendly and sustainable.

4. Is nuclear energy a viable option for India? Why or why not?

Answer: Nuclear energy is not a viable option for India because of the potential risks associated with nuclear accidents and the difficulty in handling radioactive wastes. The harmful consequences of accidents like those at Chernobyl and Fukushima show that the disadvantages of nuclear energy far outweigh its advantages. Moreover, India has significant potential for renewable sources of energy such as solar, wind, and hydel energy, which are cleaner and safer alternatives.

Extras MCQs

1. What is the estimated solar energy potential received by India per year?

A. 6,000 billion MW
B. 5,000 billion MW
C. 7,000 billion MW
D. 4,000 billion MW

Answer: A. 6,000 billion MW

Q. What temperature can a solar furnace reach?

A. 2000°C
B. 3000°C
C. 2500°C
D. 1500°C

Answer: B. 3000°C

Q. What is the power capacity of the pilot solar power plant installed in Gurgaon, Haryana?

A. 100 kW
B. 200 kW
C. 50 kW
D. 150 kW

Answer: C. 50 kW

Q. What percentage of India’s available hydroelectric energy has been utilized?

A. 11%
B. 15%
C. 23%
D. 8%

Answer: A. 11%

Q. What is the total hydroelectric potential in India from all projects?

A. 2×10¹⁰ kWh
B. 3×10¹⁰ kWh
C. 4×10¹⁰ kWh
D. 5×10¹⁰ kWh

Answer: C. 4×10¹⁰ kWh

Q. Which state in India has a wind farm at Kanyakumari generating 380 MW of electricity?

A. Tamil Nadu
B. Gujarat
C. Maharashtra
D. Karnataka

Answer: A. Tamil Nadu

Q. What is the estimated wind power potential of India?

A. 10,000 MW
B. 30,000 MW
C. 20,000 MW
D. 15,000 MW

Answer: C. 20,000 MW

Q. What is the height requirement for small hydroelectric plants to operate?

A. 5-6 meters
B. 3-4 meters
C. 2-3 meters
D. 1-2 meters

Answer: C. 2-3 meters

Q. What is a key environmental consequence of hydel energy production?

A. High deforestation
B. Noise pollution
C. Air pollution
D. Groundwater depletion

Answer: A. High deforestation

Q. What causes tides that can be harnessed for energy production?

A. Earth’s rotation
B. Wind patterns
C. Gravitational pull of the moon
D. Ocean currents

Answer: C. Gravitational pull of the moon

Q. How long do tidal power stations typically generate electricity in a 24-hour period?

A. 3-6 hours
B. 6-12 hours
C. 12-18 hours
D. 18-24 hours

Answer: B. 6-12 hours

Q. Which Indian state has identified the Gulf of Kachchh as a potential site for tidal energy?

A. Tamil Nadu
B. Gujarat
C. Maharashtra
D. Kerala

Answer: B. Gujarat

Q. What is a significant environmental concern of tidal energy?

A. Increased greenhouse gas emissions
B. Disruption of bird and fish species
C. Deforestation
D. Air pollution

Answer: B. Disruption of bird and fish species

Q. What is the estimated global potential for Ocean Thermal Energy (OTE)?

A. 500,000 MW
B. 1,000,000 MW
C. 750,000 MW
D. 250,000 MW

Answer: B. 1,000,000 MW

Q. Where was India’s first wave energy project started?

A. Mumbai
B. Chennai
C. Vizhinjam
D. Kolkata

Answer: C. Vizhinjam

Q. Which type of biomass is converted into liquid fuels like ethanol and methanol?

A. Traditional biomass
B. Non-traditional biomass
C. Agricultural residue
D. Animal waste

Answer: B. Non-traditional biomass

Q. What is a primary limitation of geothermal energy?

A. High seasonal variability
B. Limited suitable locations
C. High greenhouse gas emissions
D. Dependency on fossil fuels

Answer: B. Limited suitable locations

Q. What percentage of the world’s electricity demand is met by nuclear power?

A. 5-6%
B. 10-11%
C. 13-14%
D. 18-20%

Answer: C. 13-14%

19. What year did the nuclear reactors at Tarapur Atomic Power Station in India become operational?

A. 1965
B. 1969
C. 1972
D. 1975

Answer: B. 1969

Extra Questions and Answers

1. What are non-conventional sources of energy?

Answer: The sources of energy which are inexhaustible are called non-conventional sources of energy or renewable sources of energy.

Q. What are examples of non-conventional sources of energy?

Answer: Some examples of non-conventional sources of energy are:

• Solar energy
• Hydel energy
• Wind energy
• Geothermal energy
• Tidal energy
• Wave energy
• Ocean thermal energy
• Biomass
• Nuclear energy

Q. Which form of energy has the greatest potential?

Answer: Amongst all forms of energy, solar energy has the greatest potential. If only a small amount of this energy could be utilised, it would be one of the most important supplies of energy.

Q. How much solar energy does India receive per year?

Answer: India receives about 6,000 billion MW of solar energy per year. If only one per cent of this energy could be tapped at even 10 per cent efficiency, it would be 30 to 35 times India’s present electricity generation.

Q. What are solar energy technologies?

Answer: Solar energy technologies include:

• Solar heating
• Solar photovoltaics
• Solar thermal electricity
• Solar architecture These technologies can make considerable contributions to solving most urgent global problems.

Q. What did the International Energy Agency project about solar power?

Answer: The International Energy Agency projected that solar power could provide a third of the global final energy demand after 2060, while CO2 emissions would be reduced to very low levels.

Q. Where is a pilot solar power plant installed in India?

Answer: A pilot solar power plant of 50 kW is installed in Gurgaon in the state of Haryana, India.

Q. How can solar energy be harnessed?

Answer: Solar energy can be harnessed directly or indirectly:

• Direct Harnessing: Solar energy is used directly, as in solar cookers, solar water heaters, solar furnaces, or converted into electrical energy through solar cells.
• Indirect Harnessing: In nature, plants convert solar energy into chemical energy, which animals use as food or for fuel to produce heat energy. Solar energy also transforms into wind, water, and tidal energy, harnessed by watermills or windmills for mechanical or electric energy.

Q. How does a solar cooker work?

Answer: A solar cooker consists of a rectangular wooden box lined with insulating material. Inside the box is a metallic box painted black. A glass lid allows solar energy in but prevents radiant heat from escaping. A mirror reflector directs more solar energy into the box. The food is placed in blackened utensils, and the solar cooker is turned towards the sun. In 3-4 hours, the temperature rises to 100°C to 140°C, sufficient to cook the food.

Q. What is a solar furnace and how does it work?

Answer: A solar furnace works similarly to a solar cooker but uses thousands of small plane mirrors arranged in a curve to form a spherical concave reflector. The crucible is placed at the principal focus of the reflector, and when directed towards the sun, solar energy is concentrated on the crucible. The temperature can reach 3000°C, which is high enough to melt most materials.

Q. How does a solar water heater work?

Answer: A solar water heater consists of a blackened metallic box with a zig-zag copper pipe inside. The box is covered with a glass lid. As sunlight enters the box, it heats the water in the copper pipe. The hot water expands and moves into an insulated storage tank. Fresh cold water then replaces it in the copper pipes, setting up a convection current. Hot water is collected in the storage tank and can be used as needed.

Q. What are the uses of a solar water heater?

Answer:

• It is used in big hotels for hot water supply.
• It is used in hospitals for hot water supply.
• It is used in industries requiring hot water for certain processes.

Q. What is a solar cell?

Answer: A device which directly converts solar energy into electrical energy is called a solar cell.

Q. What is another name for a solar cell?

Answer: The solar cell is also called a photovoltaic cell.

Q. What does the term photovoltaic mean?

Answer: The term photo stands for light, and voltaic stands for the generation of potential difference. A photovoltaic cell is a device that converts light energy into electrical energy due to the generation of potential difference.

Q. What are the advantages of solar cells?

Answer:

• Solar cells are self-generating sources of electrical energy and can be used at any place.
• They provide a clean, pollution-free, and environment-friendly source of electricity.

Q. What are some uses of solar cells?

Answer:

• Solar cells are used to provide electrical energy to satellites and space probes.
• In India, they are used to power street lights and community centre televisions and radios where direct electricity supply is unavailable or unfeasible.
• They provide electricity to offshore oil rigs and lighthouses.
• Solar cells power electronic calculators, wristwatches, and toys.

Q. What is a solar panel?

Answer: A solar panel is a group of solar cells connected in a specific pattern to produce the desired potential difference and magnitude of current.

Q. How are solar cells connected in a solar panel?

Answer: The solar cells are connected to one another by silver wires because silver has the least electrical resistance.

Q. What are the advantages of solar energy?

Answer:

• Solar energy is a naturally and abundantly available, clean, pollution-free, and renewable source of energy.
• Solar photovoltaic cells are economical and can be used in satellites.
• Solar energy can be used to heat water and generate electricity.

Q. What are the limitations of solar energy?

Answer:

• A large area is required for solar collection.
• Solar radiation is highly variable during the day, across seasons, and is unavailable at night.
• It is expensive to manufacture solar panels.

Q. How is hydel energy harnessed?

Answer: Water is collected at a certain height in huge reservoirs, and its potential energy is used to fall on turbines connected to generators, producing electricity.

Q. What is the potential of hydel energy in India?

Answer: The total hydroelectric potential in India is estimated to be 4×10¹¹ kWh, of which only 11% has been utilized through major hydroelectric projects. Hydel energy accounts for 23% of the total energy generated in the country.

Q. What are the advantages of hydel energy?

Answer:

• Hydel energy is a clean and renewable energy source.
• Hydroelectric plants have a low operating cost.
• Hydro reservoirs serve multiple purposes, including water supply for drinking, irrigation, industries, and fisheries.
• Hydroelectric plants help control floods.

Q. What are the environmental consequences of hydel energy?

Answer:

• Environmental issues include earthquakes, deforestation, and submergence of villages or agricultural lands due to dam construction.
• Fish populations are affected as dams block their spawning paths.
• Financial constraints include high civil works costs and long transmission lines.

Q. What is wind energy?

Answer: Wind energy is the energy obtained from wind, which is moving air produced by temperature differences. It is used to run a windmill, which in turn drives a generator to produce power.

Q. How is electricity produced using wind energy?

Answer: Electricity is produced by using windmills. A windmill drives a generator to produce power. Since the electricity produced by a single windmill is small, a large number of windmills, called a wind farm, are erected over a large area to generate electricity on a larger scale.

Q. What is a wind farm?

Answer: A wind farm is an area where a large number of windmills are erected to generate electricity. The energy output from all the windmills is combined to produce electricity on a commercial scale.

Q. Which countries are known for wind power usage?

Answer: As of now, 83 countries are using wind power commercially. Some key countries and their wind power production include Denmark (21%), Portugal (18%), Spain (16%), Ireland (14%), and Germany (9%).

Q. Where is the largest wind farm in India located?

Answer: The largest wind farm in India is located in Kanyakumari, and it can generate 380 MW of electricity.

Q. What is the estimated wind power potential of India?

Answer: The wind power potential of India is estimated to be 20,000 MW.

Q. Where are the wind power stations located in Gujarat?

Answer: In Gujarat, wind power stations are located at Lamba in Porbandar district and Okha. The Lamba station operates with 50 wind generators and produces 2000 million units of power annually.

Q. What are the advantages of wind energy?

Answer:

• It is a renewable form of energy and is abundantly available in nature.
• It is inexpensive and pollution-free.
• It can be generated and supplied to remote areas where other energy sources are not available.

Q. What are the limitations or environmental consequences of wind energy?

Answer:

• Windmills create noise pollution and must be installed at least 500 meters away from residential areas.
• Energy generation depends on the direction and velocity of wind, which is irregular and variable.
• Wind turbines can interfere with telecommunications and aeroplanes and should be located away from airports and telecommunication towers.

Q. What causes tides and how is tidal energy generated?

Answer: Tides are caused by the gravitational pull of the sun and the moon. The rise and fall of large amounts of seawater generate mechanical energy, which can be harnessed to generate electricity using tidal power stations.

Q. How do tidal power stations generate electricity?

Answer: Tidal power stations generate electricity during the 6-12 hours of fast water flow in every 24 hours. The stored water behind a dam during high tide is released during low tide, allowing the water to flow through turbines connected to generators, converting mechanical energy into electrical energy.

Q. What are the advantages of tidal energy?

Answer:

• Tidal power is a renewable, free, and continuous source of energy.
• Tidal stations have a long lifespan and produce a large amount of energy.

Q. What are the limitations or environmental consequences of tidal energy?

Answer:

• Tidal plants can disrupt navigation systems and endanger bird and fish species.
• Pollutants can accumulate because rivers with tidal barrages are flushed less often, reducing oxygen levels and endangering aquatic life.

Q. What is geothermal energy?

Answer: Geothermal energy is the heat energy from hot rocks present inside the Earth. Under favorable conditions, this heat can be harnessed as a source of energy.

Q. Where is geothermal energy harnessed successfully in the world?

Answer: Geothermal energy is successfully harnessed in over 70 countries, including New Zealand, Iceland, and the USA. In India, geothermal energy can only be harnessed in Madhya Pradesh.

Q. What is geothermal energy?

Answer: Geothermal energy is the heat energy that originates from beneath the Earth’s surface. It is produced when the molten rocks, known as magma, collect below the Earth’s surface, in areas called hot spots.

Q. How is geothermal energy harnessed in geological regions where steam forms underground?

Answer: In certain regions, underground water comes in contact with hot spots, turning into steam. This steam gets trapped between underground rocks at very high pressure. Pipes are sunk into the ground to extract the steam, which is used to run turbines connected to generators to produce electricity.

Q. What are natural geysers, and how are they used in geothermal energy?

Answer: Natural geysers are formed when steam and hot water force their way up through cracks in the Earth’s rocks. The heat energy from these geysers is harnessed to generate electricity by using the steam to power turbines connected to generators.

Q. How is geothermal energy harnessed in areas without water underground?

Answer: In regions where underground water does not come into contact with hot spots, two holes are drilled. Cold water is pumped in through one hole, turning into super-heated steam upon contact with the hot spot. This steam emerges from the other hole and is used to run turbines connected to generators for electricity production.

Q. What are the advantages of geothermal energy?

Answer:

• It is a renewable, pollution-free source of energy.
• It is stable and reliable, unaffected by weather or seasonal changes.
• It emits far less pollution than burning fossil fuels.
• It can be used to heat water and generate electricity.

Q. What are the limitations of geothermal energy?

Answer:

• It has high initial costs due to the need for geological investigations, exploration, drilling, and assessments.
• There are only a limited number of suitable locations where geothermal energy can be harnessed.

Q. How does wave energy work?

Answer: Wave energy is harnessed by converting the vertical rise and fall of waves into mechanical or electrical energy. The amount of energy produced depends on the height and speed of the waves. Devices that capture wave energy use it to power air turbines or other systems to generate electricity or mechanical power.

Q. What is India’s first wave energy project, and how does it work?

Answer: India’s first wave energy project is located at Vizhinjam near Thiruvananthapuram. It operates on the principle of an oscillating water column, which drives an air turbine to generate power. This system allows power generation throughout the year.

Q. What are the advantages of wave energy?

Answer:

• Waves are a renewable, freely available, continuous, and stable energy source.
• Wave energy has a higher energy density per square meter compared to solar and wind energy.
• It is particularly useful in coastal areas and remote islands where other energy sources may not be practical or cost-effective.

Q. What are the limitations and environmental consequences of wave energy?

Answer:

• Severe storms can cause significant damage to wave energy plants.
• Construction of these plants along coastlines can cause issues like land erosion and corrosion of materials.
• Growth of algae or water plants like hyacinths can obstruct the passage of ships and interfere with energy production.

Q. What is ocean thermal energy (OTE)?

Answer: Ocean thermal energy is the energy generated by converting the heat contained in ocean water into electricity. This is done by utilising the temperature difference between the warm surface water heated by the sun and the colder water found at greater ocean depths.

Q. What are the advantages of ocean thermal energy?

Answer:

• It is a clean, pollution-free, and renewable source of energy.
• OTE systems can be installed in remote areas where other energy sources are not feasible.

Q. What are the limitations of ocean thermal energy?

Answer: One of the major environmental consequences of ocean thermal energy is the periodic chlorination of heat exchangers, which releases chlorine into the surrounding environment, causing potential harm.

Q. What is biomass energy?

Answer: Biomass energy refers to energy derived from organic materials such as wood, agricultural residues, and animal wastes. Biomass can be burned to produce heat or electricity, or converted into biofuels like ethanol and methanol for use in engines.

Q. What are the categories of biomass?

Answer:

• Traditional biomass: Wood and agricultural residues burned directly for energy.
• Non-traditional biomass: Organic matter converted into biofuels like ethanol and methanol.
• Biomass for domestic use: Organic matter, such as animal dung and agricultural waste, is decomposed to produce biogas for cooking and lighting.

Q. What are biogas plants, and what are the types?

Answer: Biogas plants convert organic matter into biogas through anaerobic fermentation. There are two common types:

• Fixed dome type biogas plant.
• Floating gas holder type biogas plant. Both types are often called gobar gas plants because they use animal dung (gobar) as the primary raw material.

Q. What are the advantages of biomass energy?

Answer:

• Biomass energy is economical, requiring less construction time and funding compared to large conventional energy plants.
• It creates employment opportunities in rural areas.
• It reduces dependence on fossil fuels and increases energy self-sufficiency.

Q. What are the limitations of biomass energy?

Answer: Transporting organic matter over long distances for biomass energy production can be expensive and logistically challenging, making it less advisable in some cases.

Q. How is nuclear energy generated?

Answer: Nuclear energy is produced by splitting the nuclei of heavy radioactive metals like uranium in a process called nuclear fission. Neutrons are bombarded into uranium atoms, causing them to split and release energy in a chain reaction. This energy is then used to generate electricity.

Q. What are the advantages of nuclear energy?

Answer: Nuclear energy is one of the cleanest sources of energy as it does not emit carbon dioxide or other greenhouse gases. It does not cause environmental problems like acid rain or smog.

Q. What are the limitations of nuclear energy?

Answer:

• Accidents at nuclear power plants, such as those at Three Mile Island, Chernobyl, and Fukushima, have raised concerns about the dangers of nuclear energy.
• Nuclear reactors generate radioactive waste that remains hazardous for thousands of years, and there is no fully safe method for handling or disposing of these wastes.

Q. Why do we need to promote non-conventional sources of energy?

Answer: We need to promote non-conventional sources of energy as they will minimise the use of conventional sources of energy and help to control pollution to a large extent.

Q. What are three advantages of non-conventional sources of energy?

Answer: Three advantages of non-conventional sources of energy are:

• They are renewable.
• They are inexpensive.
• They are non-polluting.

Q. What opportunity do non-conventional sources of energy provide for India?

Answer: Non-conventional sources of energy provide an enormous opportunity for India, to not only meet its energy needs but also to reap the accompanying social and environmental benefits.

65. What are some social and environmental benefits of non-conventional sources of energy in India?

Answer: Some social and environmental benefits of non-conventional sources of energy in India include:

• Local employment
• Improvement in the quality of life of women
• Participation of local institutions at the village level
• Local environmental benefits such as land reclamation and pollution abatement
• Global environmental benefits such as reduction in greenhouse gases emission.