Chapter 18 Water and Energy Conservation

NIOS Class 12 Environmental Science Chapter 18

INTEXT QUESTIONS 18.1

1. State any three factors responsible for increase in water demand.

Ans: Following factors for responsible for increasing water demand:

• a. Expansion of irrigation
• b. Increasing demand by the industry
• c. Rising demand due to growing population
• d. Increasing water use due to a changing lifestyle

2. Name two environmentally effective systems of irrigation.

Ans: Low-pressure sprinklers and micro irrigation.

3. Why should water be conserved?

Ans: To overcome the problem of scarcity of water, we need to judiciously use water and conserve it for the use of future generations.

4. Mention any two ways an individual can help in conserving water.

Ans: 

• (1) By making people aware of water scarcity, so that they may use it judiciously. 
• (2) Never waste water. Get the leaking pipes and taps required. Use only as much water as needed. 
• (3) Close taps between brushing your teeth, bathing and shaving. 
• (4) Collect rainwater and use it for domestic use. 

5. Mention one important cause of water scarcity in our country.

Ans: Growing population.

INTEXT QUESTIONS 18.2

1. State in a sentence how TV can help in spreading awareness regarding water conservation.

Ans: Awareness programmes in the form of small skits or conversations, or cartoons, can reach a large population.

2. Why is it more sensible to irrigate plants and lawns in early morning or late evening?

Ans: Because transpiration is low so water loss is reduced.

3. In your opinion, what can be done to motivate people to reduce wastage of water?

Ans: Change an appropriate amount of water consumption.

4. State one method of recharging groundwater.

Ans: Recharging of groundwater

• Flood waters may be injected into aquifers (underground water reservoirs) through a series of deep pits or ditches.
• Small reservoirs and percolation tanks can be dug to hold runoff water, recharging groundwater. 
• Rainwater harvesting is carried out by building a system for recharging groundwater.
• Storm water, used water, and domestic drains can be fed into pits, trenches, or depressions to be filtered and percolated through the soil for recharging groundwater.
• Desilting of canals and tanks should be done regularly.
• Pre-monsoon tillage of fields helps to conserve soil moisture.

5. What is the role of algae or aquatic plants like water hyacinth in removing pollutants from wastewater?

Ans: Growing algae or floating masses of water hyacinth also helps in cleaning the water polluted by absorbing phosphates, nitrates and other nutrients. These aquatic plants can be harvested to produce biogas.

6. What are GAP and YAP?

Ans: Ganga Action Plan and Yamuna Action Plan.

7. Why are such action plans undertaken?

Ans: Many of the Indian rivers are polluted, and their waters over large stretches are unfit for human use. River pollution is mostly from the discharge of effluents by industries, and cities developed along river courses. This is why the government has launched such action plans to clean up the rivers. 

8. Name two more important rivers of our country?

Ans: Ganga, Yamuna, Brahmaputra, Sutlej, Krishna, Narmada, Kaveri, Godavari, etc.

INTEXT QUESTIONS 18.3

1. Define energy.

Ans: Energy may be defined as the capacity to do work. Energy can be transformed from one form to another.

2. List four human activities for which energy is required.

Ans: Humans need energy to carry out various kinds of activities, such as 

• Heat or electrical energy is required for cooking and heating
• Electricity is required for lighting bulbs and tube lights, running fans, coolers and air conditioners.
• Fuel such as petrol or diesel, or compressed natural gas (CNG) is required in vehicles such as cars, buses, trains, trucks, aeroplanes, which are responsible for transporting human beings and goods from one place to another.
• Energy (electricity) is required for pumping water up the multi-storied buildings.
• Energy is required for the various industrial processes that ultimately result in the manufacture of different kinds of goods.
• Energy is required in agriculture for irrigation, tractors and other farm machines, and spraying pesticides.
• Energy is required in power generation, e.g. rotating the turbines in hydroelectric power generation.

3. Name the energy compound synthesised by human beings.

Ans: ATP or Adenosine triphosphate.

INTEXT QUESTIONS 18.4

1. Distinguish between non-renewable and renewable sources of energy.

Ans: Non-renewable energy is limited in supply; Renewable energy is available in an unlimited amount.

2. Name one conventional and one non-conventional source of energy.

Ans: Conventional- coal or petroleum: Non-conventional energy, hydel energy, tidal energy, or biomass. 

3. Name three fossil fuels.

Ans: Coal, natural gas, and Petroleum (oil).

4. Name one biodiesel-yielding plant.

Ans: Jatropha, Callophyllum, Hevea (Rubber).

5. What do you mean by (a) biomass and (b) biogas?

Ans: 

• Biomass: Plant matter.
• Biogas: Gas used as fuel, containing CH₄ and made by the action of anaerobic bacteria on organic waste.

6. Name two chemical compounds which can be called biofuels.

Ans: Ethanol, Methane.

7. Why are they termed biofuels?

Ans: Because they are obtained from plants or by bacteria, both of which are biological organisms.

INTEXT QUESTIONS 18.5

1. Mention how you improve energy efficiency at home, at the workplace and in the transport sector. Give two points in each.

Ans: 

• i. Switch off the light, fan and AC when not in use, use gas at a simmer level, which saves cooking gas.
• ii. Switch off light, fan and AC when not in use, use car pool to reach office, use CFL, and computer to be switched off when not in use.
• iii. Car speed should be maintained at 50-60 km/h, turn off the vehicle engine at stops rather than idling. (Any other)

2. Expand the following: MNRE, IREDA, CFL

Ans: 

• MNRE- Ministry of New and Renewable Energy
• IREDA- The Indian Renewable Energy Development Agency
• CFL- Compact Fluorescent Light Bulbs

3. Why have people started using CFLs at home?

Ans: Energy consumption is low, hence it cuts down the electricity bill.

4. What does BEE stand for? What is its function?

Ans: Bureau of Energy Efficiency – the function of BEE is to develop a programme to increase conservation and efficient use of energy in India.

5. What is the difference between ‘one-star’ and ‘five-star’ refrigerators?

Ans: The 5-star refrigerator is significantly more energy efficient and consumes much less electricity than the 1-star refrigerator, which leads to lower electricity bills over time. 

TERMINAL EXERCISE

1. State the factors responsible for water scarcity.

Ans: Several factors responsible for water scarcity are –

• (i) Increased demand of an increasing population.
• (ii) Increasing demand by expansion of irrigation and its demand.
• (iii) Increasing water use due to lifestyle changes.
• (iv) Silting of rivers
• (v) Bad management of water resources.

2. Mention the strategies for water conservation.

Ans: We can conserve water by using various methods such as reforestation, re-use, recycling, increasing water use efficiency, water harvesting and groundwater recharge.

• Reforestation is the process of planting trees in deforested areas or of increasing tree cover from regrowth and planting of trees (plantations). Reforestation increases soil fertility by preventing soil erosion, preventing run-off of eroded soil into aquatic systems and preventing flooding. Thus, reforestation plays a major role in the conservation of water.
• The wastewater from industrial or domestic sources can be used after proper treatment for irrigation, recharging groundwater water and even for industrial and municipal use.
• Wastewater containing lots of nutrients and thus may help the growth of plants when such water is used in irrigation. Reuse of wastewater occurs most effectively with an on-site or small treatment system.
• Water harvesting is collecting rainwater that falls on a house or on and around any building and then putting it to use later on, or simply replenishing the groundwater by allowing the water to reach underground.
• Recharge groundwater by harvesting rainwater through various methods. 

3. What is water harvesting? In what ways can it be done?

Ans: Water harvesting is collecting rainwater that falls on a house or on and around any building and then putting it to use later on, or simply replenishing the groundwater by allowing the water to reach underground. Various methods of water management, including capturing water from swollen streams and rivers during the monsoon season and storing it in various forms of water bodies.

• Flood water may be injected into aquifers through a series of deep pits or ditches.
• Small reservoirs and percolation tanks can be dug to hold runoff water, recharging groundwater.
• Storm water, used water (municipal and domestic), and domestic drains can be fed into pits, trenches, or depressions to be filtered and percolated through the soil for recharging groundwater.
• Desilting of canals and tanks should be done regularly.
• Premonsoon tillage of fields helps to conserve soil moisture.

4. Write short notes on: Ganga Action and Yamuna Action Plan.

Ans: 

• Ganga Action Plan or GAP: Ganga is the largest and most important Indian river. It is 2,525 Km long. The watershed of the river Ganga spreads over ten Indian states. The major cause of Ganga water pollution is unrestricted discharge of untreated sewage and industrial effluents along its course. Ganga Action Plan (GAP) is an ambitious and first-of-its-kind river cleaning project. Ganga Action Plan(GAP) has been launched by the Government of India to clean the river Ganga. The first phase of the project was completed in 1993.
• Yamuna Action Plan (YAP) was implemented in April 1993 under the banner- “Yamuna Ko Swacch Banana Hai. Hum Sabko Haath Batana Hai”. The Yamuna is a major tributary of the river Ganga. Yamuna Action Plan (YAP) aims at cleaning and conserving the water of the river Yamuna by removing pollutants from it.

5. What are conventional and non-conventional energy resources? Explain with examples.

Ans: The conventional sources of energy are the fossil fuels. It took millions of years for the formation of fossil fuels; hence, they are limited and non-renewable. Fossils are remains of organisms that lived in the past, and fossil fuels are plants that got buried under the earth and became rock over the years. Fossil fuels have to be unearthed from mines. Most fossil fuels release energy as heat. The types of fossil fuels are:

• 1. Coal is solid. It is mined and then transported in trucks and trains. 
• 2. Oil is a liquid which is pumped out from the ground after drilling a well. It is sent to faraway places in oil tankers or pipelines 
• 3. Natural gas is a mixture of gases. The gas we use for cooking, which comes in cylinders, is LPG or Liquefied Petroleum Gas. Compressed Natural gas or CNG is used in public transport vehicles (buses, scooters, auto-rickshaws and taxis).

6. What are biofuels?

Ans: Biofuels are obtained from plants and plant products and may be in the form of liquid (Bioethanol) or may be obtained as CO₂ and CH₄ (biogas). Oil seeds of plants like Jatropha, Hevea and Callophyllum yield biodiesel.

7. Write notes on (i) Biogas digesters,(ii) Biodiesel, (iii) Fossil fuels

Ans: 

• Biogas digesters are large vessels in which organic wastes (plants and animals’ waste) are made to undergo bacterial fermentation and produce biogas, which can be used for heating and cooking.
• Biodiesel is obtained from vegetable oils. Biodiesel does not contain any petroleum, but it substitutes for petroleum in the same conventional engines. It is obtained from are
  • (1) Ratanjot or Jatropha curcas 
  • (2) Nagchampa or Callophyllum ionophyllum 
  • (3) Rubber seeds or Hevea braziliensis. 
• Fossil fuels are plants that were buried under the earth and became rock over the years. Examples of fossil fuels are coal, petroleum, natural gas, such as LPG and CNG. 

8. What are the ways of conserving energy as an individual?

Ans: 

• At home
  • Switch off lights and fans when not in use, minimise use by sharing to sit and work in one place.
  • Use fuel-efficient hearths (chulhas) for cooking. Do not use smoking stoves.
  • Use the gas at a simmer level. It saves cooking gas and makes the cooked item healthier and tastier.
  • Keep the material ready for cooking before lighting the gas so that it does not burn unnecessarily.
• At work place
  • Use car carpool to reach the office – share the transport vehicles.
  • The computer to be switched off when not in use.
• In transport
  • To use the public transport system as much as possible. 
  • Car speed should be maintained as far as possible, 50 to 60km/hr. 
  • Take care to check and mend leaks in the fuel tanks and exhausts of vehicles.
  • Turning off a vehicle’s engine at stops rather than idling.

9. What is the need for making electrical gadgets/equipment with a star rating?

Ans: The BEE Star Energy Efficiency Labels have been created to standardise the energy efficiency ratings of different electrical appliances and indicate energy consumption under standard test conditions. These labels indicate the energy efficiency levels through the number of stars highlighted in colour on the label. Star rating system ranges from one star (least energy efficient, thus least money saved) to five stars (most energy efficient, thus most money saved).

10. How can transport vehicles be made energy efficient?

Ans: 

• Using CNG in vehicles instead of petroleum fuels. 
• Use car carpool to reach the office – share the transport vehicles.
• Take care to check and mend leaks in fuel tanks and exhausts of vehicles.
• Turning off a vehicle’s engine at stops rather than idling.

11. Mention three ways of using solar energy as an energy resource.Ans: Solar energy is now harnessed through “solar panels” directly, which heat homes by solar radiation. Solar photovoltaic cells are used in solar TVs, and solar thermal energy is used to cook food in solar cookers. Solar energy is also used in industries.

Additional Study Materials

• Chapter 14 Global Environmental Issues
• Chapter 15 Biodiversity Conservation
• Chapter 16 Conservation of Other Natural Resources
• Chapter 17 Conservation of Soil and Land