8.2: World Energy Sources

Question 1

8.2.1: Identify different world energy sources (8)

Answer 1

oil, natural gas, coal, nuclear, hydroelectric, photovoltaic cells, biofuel, geothermal

Question 2

8.2.2: Outline and distinguish between renewable and non-renewable energy sources

Answer 2

Non-renewable sources are finite sources, which are being depleted, and will run out. They include fossil fuels (oil, natural gas and coal), and nuclear fuels (uranium). The energy stored in these sources is, in general, a form of potential energy, which can be released by human action.
Renewable sources include solar energy, other forms indirectly dependent on solar energy (wind and wave energy) and tidal energy

Question 3

8.2.3: Define the energy density of a fuel

Answer 3

Energy density is the energy that can be obtained from a unit mass of the fuel.

Question 4

What is energy density measured in?

Answer 4

Energy density is measured in J kg-1

Question 5

8.2.4: Discuss how choice of fuel is influenced by its energy density (3)

Answer 5

Transport costs
Storage
Application

Question 6

8.2.4: Discuss how choice of fuel is influenced by its energy density (3)

Answer 6

Transport costs
Storage
Application

Question 7

What is the percent of total energy produced for oil?

Answer 7

40%

Question 8

What is the percent of total energy produced for natural gas?

Answer 8

23%

Question 9

What is the percent of total energy produced for coal?

Answer 9

23%

Question 10

What is the percent of total energy produced for nuclear?

Answer 10

7%

Question 11

What is the percent of total energy produced for hydroelectric?

Answer 11

7%

Question 12

What are the advantages of fossil fuels? (4)

Answer 12

Relatively cheap (while they last)
• High power output (high energy density)
• Variety of engines and devices use them directly and easily
• Extensive distribution network is in place

Question 13

What are the disadvantages of fossil fuels? (5)

Answer 13

• Will run out
• Pollute the environment
• Contribute to greenhouse effect by releasing greenhouse gases into atmosphere
• High cost of distribution due to high mass and volume of materials and high cost of storing (needs extensive storage facilities)
• Pose serious environmental problems due to leakages at various points along the production

Question 14

What are the advantages of nuclear energy? (3)

Answer 14

• High power output
• Large reserves of nuclear fuels
• Nuclear power stations do not produce greenhouse gases

Question 15

What are the disadvantages of nuclear energy? (4)

Answer 15

• Radioactive waste products difficult to dispose of
• Major public health hazard should ‘something go wrong’
• Problems associated with uranium mining
• Possibility of producing materials for nuclear weapons

Question 16

What are the advantages of solar power/photovoltaic cells? (3)

Answer 16

• “Free”
• Inexhaustible
• Clean

Question 17

What are the disadvantages of solar power/photovoltaic cells? (5)

Answer 17

• Works during the day only
• Affected by cloudy weather
• Low power output
• Requires large areas
• Initial cost high

Question 18

What are the advantages of hydroelectric power? (3)

Answer 18

• “Free”
• Inexhaustible
• Clean

Question 19

What are the disadvantages of hydroelectric power? (3)

Answer 19

• Very dependent on location
• Requires drastic changes to environment
• Initial costs high

Question 20

What are the advantages of wind power? (4)

Answer 20

• “Free”
• Inexhaustible
• Clean
• Ideal for remote island locations

Question 21

What are the disadvantages of wind power? (5)

Answer 21

• Works only if there is wind – not dependable
• Low power output
• Aesthetically unpleasant (and noisy)
• Best locations far from large cities
• Maintenance costs high

Question 22

What are the advantages of wave power? (4)

Answer 22

• “Free”
• Inexhaustible
• Clean
• Reasonable energy density

Question 23

What are the disadvantages of wave power? (6)

Answer 23

• Works only in areas with large waves
• Irregular wave patterns make it difficult to achieve reasonable efficiency
• Difficult to couple low-frequency water waves with high-frequency turbine motion
• Maintenance and installation costs high
• Transporting the produced power to consumers involve high costs
• Devices must be able to withstand hurricane and gale-force storms.