P3 (Physics): Sustainable Energy

This section shows links to revision materials Physics P3 - Sustainable Energy

Overview of Module

Energy supply is one of the major issues that society must address in the immediate future. Citizens are faced with complex choices and a variety of messages from energy supply companies, environmental groups, the media, scientists and politicians. Some maintain that renewable resources are capable of meeting our future needs, some advocate nuclear power, and some argue that drastic lifestyle changes are required. Decisions about energy use, whether at a personal or a national level, need to be informed by a quantitative understanding of the situation, and this is an underlying theme of the module.

Candidates first survey the ways in which individuals and organisations use energy, and learn how energy demand and use can be measured. They explore the use of energy-efficient devices (e.g. light bulbs) and consider the quantitative consequences of various lifestyle choices (e.g. relating to transport and the use of electrical equipment). National data on energy sources introduce a study of electricity generation and distribution; nuclear power generation, the burning of fossil fuels, and renewable resources are compared and contrasted. Finally, candidates review the energy choices available to individuals, organisations and society.

Physics

P3 - Sustainable Energy (click on the links below for general headings or look below for more detail on what you may be tested on)

• Using energy,
• Generating electricity,
• Choosing energy source

P3.1 How much energy do we use?

1. understand that the demand for energy is continually increasing and that this raises issues about the availability of energy sources and the environmental effects of using these sources

2. recall the main primary energy sources that humans use: fossil fuels (oil, gas, coal), nuclear fuels, biofuels, wind, waves, and radiation from the Sun

3. understand why electricity is called a secondary energy source

4. understand that power stations which burn fossil fuels produce carbon dioxide which contributes to global warming and climate change

5. understand that when electric current passes through a component (or device), energy is transferred from the power supply to the component and/or to the environment

6. recall that the power (in watts, W) of an appliance or device is a measure of the amount of energy it transfers each second, i.e. the rate at which it transfers energy

7. use the following equation to calculate the amount of energy transferred in a process, in joules and in kilowatt hours:

• energy transferred (joules, J, kilowatt hours, kWh )= power (watts, W, kilowatts, kW) × time (seconds, s, hours, h)

8. use the following equation to calculate the rate at which an electrical device transfers energy:

• power (watts, W) = voltage (volts, V) × current (amperes, A)

9. understand that a joule is a very small amount of energy, so a domestic electricity meter measures the energy transfer in kilowatt hours

10. calculate the cost of energy supplied by electricity given the power, the time and the cost per kilowatt hour

11. interpret and process data on energy use, presented in a variety of ways

12. interpret and construct Sankey diagrams to show understanding that energy is conserved

13. use the following equation in the context of electrical appliances and power stations:

• efficiency = (energy usefully transferred / total energy supplied) × 100%

OR

• efficiency = (power usefully transferred / total power supplied) × 100%

NOTE:  Candidates will be expected to consider / calculate efficiency as a decimal ratio and as a percentage

14. suggest examples of ways to reduce energy usage in personal and national contexts.

P3.2 How can electricity be generated?

1. understand that electricity is convenient because it is easily transmitted over distances and can be used in many ways

2. recall that mains electricity is produced by generators

3. understand that generators produce a voltage across a coil of wire by spinning a magnet near it

4. understand that the bigger the current supplied by a generator, the more primary fuel it uses every second

5. understand that in many power stations a primary energy source is used to heat water; the steam produced drives a turbine which is coupled to an electrical generator

6. label a block diagram showing the basic components and structures of hydroelectric, nuclear and other thermal power stations

7. understand that nuclear power stations produce radioactive waste

8. understand that radioactive waste emits ionising radiation

9. understand that with increased exposure to ionising radiation, damage to living cells increases eventually leading to cancer or cell death

10. understand the distinction between contamination and irradiation by a radioactive material, and explain why contamination by a radioactive material is more dangerous than a short period of irradiation from the radioactive material

11. understand that many renewable sources of energy drive the turbine directly e.g. hydroelectric, wave and wind

12. interpret a Sankey diagram for electricity generation and distribution that includes information on the efficiency of energy transfers

13. recall that the mains supply voltage to our homes is 230 volts

14. understand that electricity is distributed through the National Grid at high voltages to reduce energy losses.

P3.3 Which energy sources should we choose?

1. discuss both qualitatively and quantitatively (based on given data where appropriate), the effectiveness of different choices in reducing energy demands in:

• a. domestic contexts
• b. work place contexts
• c. national contexts

2. understand that the choice of energy source for a given situation depends upon a number of factors including:

• a. environmental impact
• b. economics
• c. waste produced
• d. carbon dioxide emissions

3. describe advantages and disadvantages of different energy sources, including non-renewable energy sources such as:

• a. fossil fuels
• b. nuclear and renewable energy sources such as:
• c. biofuel
• d. solar
• e. wind
• f. water (waves, tides, hydroelectricity)
• g. geothermal

4. interpret and evaluate information about different energy sources for generating electricity, considering:

• a. efficiency
• b. economic costs
• c. environmental impact
• d. power output and lifetime

5. understand that to ensure a security of electricity supply nationally, we need a mix of energy sources.