7.2 Energy sources — uses and managementIB Environmental Systems and Societies SL: Subtopic test

1. 1
   Global primary energy consumption has risen in almost every year since 1950, with only brief falls such as in 2009 and 2020. Over the same period the world's population has more than tripled, and the average amount of energy used by each person has also increased. Today about four-fifths of the energy used worldwide still comes from coal, oil and natural gas.

   (a)

   Which of the following is classified as a renewable energy source?

   [1 mark]

   • ANatural gas
   • BTidal energy
   • CCoal
   • DCrude oil

   (b)

   Which pair of factors best explains the long-term rise in global energy consumption?

   [1 mark]

   • AA falling population and falling demand per person
   • BA rising population with no change in demand per person
   • CA falling share of energy from fossil fuels
   • DA rising population and rising demand per person

   (c)

   Distinguish between renewable and non-renewable energy sources.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   Morocco has few fossil fuel reserves and imports most of the energy it uses. It has set a target of producing around half of its electricity capacity from renewable sources by 2030. At Ouarzazate, on the edge of the Sahara, the Noor solar complex uses mirrors to concentrate sunlight and heat a molten salt. The salt stores the heat and allows electricity to be generated for several hours after sunset.

   (a)

   Which term describes energy production that varies with the time of day and the weather, as solar power does?

   [1 mark]

   • AIntermittent
   • BFinite
   • CNon-renewable
   • DContinuous

   (b)

   Which factor most directly makes solar energy a suitable choice for Morocco?

   [1 mark]

   • ALarge domestic reserves of coal
   • BAbundant large rivers suitable for hydroelectric dams
   • CHigh levels of sunshine and large areas of desert land
   • DA large existing network of oil refineries

   (c)

   Explain how the molten salt storage helps to overcome a limitation of solar energy.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A country's electricity use is summarised as follows. In 2000 its population was 40 million and each person used on average 2.0 MWh of electricity per year. In 2020 its population was 50 million and each person used on average 2.8 MWh per year. In 2020, 60% of the country's electricity was generated from imported natural gas, and the government is considering a programme to subsidise building insulation and efficient appliances.

   (a)

   Calculate the percentage increase in the country's total annual electricity use between 2000 and 2020. Show your working.

   [3 marks]

   (b)

   Using the data, explain why total electricity use has risen faster than the population, and discuss how energy conservation and efficiency could reduce the country's dependence on imports.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   Samsø is a Danish island with about 3,700 residents. In the 1990s it won a national competition to become a renewable energy island. By 2007 it generated more renewable electricity than its residents used, mainly from wind turbines on land and at sea. Many homes are heated by district heating plants fuelled by straw and wood chips. Surplus electricity is exported to mainland Denmark by undersea cable, and electricity is imported when the wind is weak. Transport on the island still depends largely on petrol and diesel.

   (a)

   Evaluate the sustainability of Samsø's use of wind and biomass compared with the use of coal-fired power stations.

   [6 marks]

   (b)

   Discuss the factors that would affect whether another country could copy Samsø's approach to energy.

   [6 marks]

   Total for question 4: 12 marks

End of questions