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.
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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.
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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
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.
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.
Ron’e Dutta is a journalist, teacher, aspiring novelist, and blogger who manages Online Free Notes. An avid reader of Victorian literature, his favourite book is Wuthering Heights by Emily Brontë. He dreams of travelling the world. You can connect with him on social media. He does personal writing on ronism.
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