Chapter 29B Renewable Sources of Energy – I

NIOS Class 12 Environmental Science Chapter 29B

INTEXT QUESTIONS 29.1

1. What do you consider the single most important natural energy resource? Why?

Ans: Sun is one of the most important natural energy sources. All other energy sources are directly derived from the sun.

2. Give three examples of conventional and non-conventional sources of energy.

Ans: Coal, oil, and natural gas are examples of conventional energy, while solar, hydro power, wind, nuclear, biogas, and geothermal energy are examples of non-conventional sources of energy (any three examples)

3. Give one point of difference between conventional and non-conventional sources of energy.

Ans: 

• It has been in use for a long time
• Are other than the usual or those that are different from those in common practices.

4. Differentiate between non-renewable and renewable energy sources.

Ans: 

• Non-renewable: Mostly fossil fuels found under the ground
• Renewable: Mostly non-fossil fuels seen above the ground.

INTEXT QUESTIONS 29.2

1. Why is solar energy is most important renewable type of energy?

Ans: Solar energy is the most important renewable energy because it is the most abundant present, it is present all the time, and is everlasting and available free of cost.

2. Describe the various uses of solar energy.

Ans: Solar energy is used in a passive manner, directly in drying food and clothes, to evaporate seawater to get salt. Solar cookers use solar energy for cooking, and solar energy is used directly for heating and lighting buildings. Solar energy is used in an active way to produce hot water for domestic use.

3. What are photovoltaic cells, and how do they work?

Ans: A Photovoltaic cell is a solar cell to produces electricity from solar energy. It is a thin, wafer-like semiconductor. Sunlight energizes and causes electrons to flow in the semiconductor, producing an electrical current.

INTEXT QUESTIONS 29.3

1. What is the difference between air and wind?

Ans: Moving air is called wind. Uneven absorption of solar radiation by Earth’s surface causes differences in temperatures, density, and pressure, which produce air movements or wind.

2. Why is wind energy called indirect solar energy?

Ans: It is the solar energy of the sun that causes the kinetic energy of wind.

3. What is the significance of dams in the production of hydroelectricity?

Ans: Dams are built on rivers to store water at a higher level, which is made to fall to rotate turbines that generate electricity. Generation of electricity by using the force of falling water is called hydroelectricity.

TERMINAL EXERCISE

1. List the various uses of solar energy and describe the advantages and disadvantages of solar energy.

Ans: Solar energy is one of the most important sources of energy, which is used for heating and cooling of buildings, for cooking food, and generating electricity. The limitation with solar energy is that on a cloudy day or in winter, it is not available, and the current technologies are fairly limited.

2. Why are photovoltaic cells considered to be an ideal solar energy collection device? What are some of their limitations?

Ans: Solar energy can be converted directly into electrical energy (direct current, DC) by photovoltaic (PV) cells, commonly called solar cells. Solar cells can provide electricity to remote villages. India is the world’s largest market for solar cells. Its biggest disadvantage is that it is expensive to install. 

3. What are the limitations of tidal power as a source of electricity?

Ans: Tidal power is another renewable energy resource, but suitable sites for harnessing this energy are limited, and technologies are few.

4. Discuss the advantages and disadvantages of hydropower energy.

Ans: Hydroelectric power is used for generating energy. It is also an indirect form of solar energy and has several advantages, but the high construction cost and silting of reservoirs, which lesson the life of power stations, are the main drawbacks.

5. Which has greater future potential for energy production, wind or water power? Also, discuss which one of these you think has more environmental problems?

Ans: In present times, the greatest potential for using wind is for the production of electricity. Wind turbines, like windmills, are mounted on a tower to capture most of the wind energy. Windmills can be used to drive generators to produce electricity.

Water energy poses more environmental problems. Hydropower also has some disadvantages; building of dam seriously disturbs and damages the natural habitats, and some of them are lost forever. Human habitations also get disturbed, making people homeless.

6. Discuss why our country is not utilizing the renewable resources to their fullest potential.

Additional Study Materials

• Chapter 27B Importance of Energy in Society
• Chapter 28B Non-Renewable Sources of Energy