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Physics 21st Century > Sustainable :( Energy :( > Flashcards

Sustainable :( Energy :( Flashcards

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1
Q

What is a primary energy source?

A

Fuel that is used in the form in which it is found.

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2
Q

Name some primary energy sources?

A

Fossil fuels; nuclear fuel; biofuels

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3
Q

What are secondary energy sources?

A

Energy that has been converted from a primary source, eg electricity

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4
Q

Where does most of our energy come from?

A

Burning fossil fuels

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5
Q

What is the burning of fossil fuels doing to the atmosphere?

A

Increasing the CO2

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6
Q

Why is it a problem that we are increasing the amount of CO2 in the atmosphere?

A

The greenhouse effect is causing global warming

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7
Q

What is likely to happen as the result of global warming?

A

Climate change; floods and storms

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8
Q

What is power?

A

The amount of energy transferred in one second

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9
Q

What is power measured in?

A

Watt

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10
Q

What is a watt?

A

1 joule in 1 second

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11
Q

What is the equation for energy transfer?

A

Energy transferred (J) = Power (W) x Time (s)

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12
Q

What is domestic electricity measured in?

A

KWh (Kilowatt -hours)

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13
Q

What is a kilowatt-hour?

A

The energy transferred by 1kW in an hour

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14
Q

What is the flow of electricity called?

A

Current

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15
Q

What is current measured in?

A

Ampère (Amp)

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16
Q

What is the voltage of a power supply measured in?

A

Volts

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17
Q

How can the rate of power transfer to an electrical device be measured?

A

Power (W) = current (A) x voltage (V)

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18
Q

What is the power of an electrical device?

A

The rate at which it transfers energy from the power supply. This is often called the rating.

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19
Q

What energy transfers occur when a current flows in a circuit?

A

Energy in the component transfers the energy into other useful forms; energy in the wires is converted into heat

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20
Q

How would you draw a diagram to show energy transfers?

A

Sankey diagram. The thickness of each arrow tail is proportional to the energy. Wasteful energy always flows down, useful energy to the right.

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21
Q

What is the efficiency of an electrical component?

A

Efficiency = energy usefully transferred/ total energy supplied

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22
Q

What can the values for efficiency be?

A

Between 1 and 0. Greater than 1 means you are creating energy.

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23
Q

How can you use less energy?

A

Use high efficiency A rated components; turning off components when they are not needed; not boiling more water than needed; cooking in the microwave.

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24
Q

What can the nation do to use less energy?

A

Use more efficient cars; live in houses with better insulation; building more efficient power stations.

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25
Q

What will happen to global demand for energy?

A

It will rise due to population increases and increasing standard of living.

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26
Q

Which human activities have no impact on the environment?

A

They all do.

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27
Q

How can we reduce human impact on the environment?

A

recycling resources such as plastic, glass, paper; generating electricity from renewable sources of energy, eg water, wind, solar power.

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28
Q

What happens when you move a magnet near a circuit?

A

Current flows.

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29
Q

When does the flow of current induced by a magnet stop?

A

When the magnet stops moving.

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30
Q

How does a generator work?

A

A magnet is spun near a coil of wire.

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31
Q

How is the primary fuel in a power station used?

A

It boils water into steam, the steam pressure turns the turbines which spin the magnet.

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32
Q

How can turbines be turned directly?

A

Wind and water.

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33
Q

How does a spinning turbine make electricity?

A

It spins the shaft of the generator (and therefore the magnet)

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34
Q

How is the turbine set spinning?

A

By steam, hot exhaust gas, wind, water.

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35
Q

How do thermal power stations spin the turbine?

A

They burn the fuel to make steam. Some also use the hot exhaust gases to spin another turbine (mainly gas power stations do that).

36
Q

How do hydro-electric power stations spin the turbine?

A

High pressure of water.

37
Q

How do wind power stations spin the turbine?

A

They are using the convection currents in the air to spin the turbine, so solar energy

38
Q

How do nuclear power stations spin the turbines?

A

They use the radioactive road to heat high pressure water which is cooling the fuel rods, which boils low pressure water, which produces steam, which spins the turbine.

39
Q

What is the problem with the waste from nuclear power stations?

A

It is still radioactive, and therefore a health risk

40
Q

What must be done with nuclear waste?

A

It has to be stored safely until it stops being dangerously radioactive.

41
Q

What sort of radiation is emitted by nuclear waste?

A

Ionising radiation

42
Q

What can ionising radiation do to body cells?

A

It can damage them

43
Q

When an object is placed in the path of nuclear radiation it is

A

Irradiated

44
Q

When an object has radioactive material mixed up with it it is

A

Contaminated

45
Q

Why do we over-estimate the risks from ionising radiation?

A

We can’t see it, or feel it; the effects can take a long time to develop; people worry about unfamiliar technology

46
Q

Why is contamination much more serious than irradiation?

A

It can give a longer exposure to radiation; it is difficult to remove the radioactive material; it can be hard to stop the radioactive material from spreading.

47
Q

What can statistics about death rates tell us?

A

They can be used to compare risks from different technologies; decide which technology needs to be controlled; decide which risks are too small to worry about.

48
Q

How would you compare the risks of different technologies?

A

You take in to account the likelihood of an event, and the consequence of the event. The worse the consequences, the lower the acceptable likelihood.

49
Q

What is an energy source that can be used over and over again?

A

Renewable

50
Q

What are renewable sources of energy to spin turbines?

A

hydroelectric; wind; wave

51
Q

Name advantages of hydroelectricity

A

They can provide large amounts of electricity; can respond to fluctuations in demand very quickly; can use excess power in the grid to pump water back up the hill

52
Q

Name advantages of wind turbines

A

They are inexpensive to make, and cheap to maintain

53
Q

Name disadvantages of hydroelectricity

A

They flood large areas of land; methane produced when plants rot in water; cost a lot to build

54
Q

Name disadvantages of wind turbines

A

They need to be put in windy places; they can only generate electricity when it is windy enough; they kill birds.

55
Q

Name advantages/disadvantages of wave power

A

Still experimental, not yet known

56
Q

How can the environmental impact of renewable energy schemes be reduced?

A

By careful planning - wind turbines offshore; using hydroelectric dams to control rivers.

57
Q

Why is electricity convenient?

A

It can transfer energy over long distances

58
Q

What is the National Grid?

A

A network of cables that carries electricity over the whole of the UK

59
Q

Why do power cables warm up?

A

Because they are wastefully transferring electric energy to thermal energy

60
Q

How can you decrease the current while keeping the power constant?

A

Increase the voltage

61
Q

How does the National Grid reduce wasteful energy transfers in the cables?

A

They use very high voltage.

62
Q

How is the electricity changed for our homes?

A

Substations change the voltage to 230v

63
Q

Where is the most energy wasted in the process of generating electricity and transferring it to homes?

A

In the power stations.

64
Q

What is the efficiency of energy generation (including the national grid) in the UK?

A

.33

65
Q

Which energy sources can generate large amounts of power?

A

Fossil fuels; nuclear power; hydroelectricity; biofuels.

66
Q

Which energy sources for generating electricity rely on the right weather?

A

Wind; waves; solar

67
Q

Energy sources that do not produce greenhouse gases?

A

Nuclear power; wind; waves; solar; geothermal

68
Q

What is the environmental impact of using fossil fuels?

A

Greenhouse gases; extraction can be pollution risk; extraction can be dangerous

69
Q

What is the environmental impact of using nuclear power?

A

Radioactive waste

70
Q

What is the environmental impact of wind farms?

A

Noise, visual pollutions, concerns about possible bird deaths

71
Q

What is the environmental impact of tidal and hydroelectric dams?

A

Flood large areas

72
Q

Which energy sources will run out?

A

Fossil fuels; nuclear power

73
Q

Which energy sources are free?

A

Wind; hydroelectric; tidal; solar; geothermal

74
Q

What do you need to consider when choosing an energy source?

A

Environmental impact; cost of building and running the power stations; how much carbon dioxide and other waste it produces; reliability of the energy source; sustainability of the energy source; efficiency of transfer of energy

75
Q

How is the output of a power station measured?

A

Millions of Watts - megawatts

76
Q

What is the output of a power station using fossil fuels or radioactivity?

A

About 1000MW and it lasts about 40 years,

77
Q

What power output do windfarms have?

A

About 300 MW, and lasts about 20 years.

78
Q

What power output can hydroelectric power stations have?

A

About 10,000 MW, and last 80 years.

79
Q

What have countries agreed to do in response to global warming?

A

Reduce their production of CO2

80
Q

How will countries reduce the CO2 they produce?

A

Use less energy for heating, transport, electricity

81
Q

How do vehicles, factories and power stations reduce their CO2 emissions?

A

Become more efficient.

82
Q

Why is global demand for energy likely to rise?

A

Increasing population; increased standard of living

83
Q

Why do people in industrialised countries have to use less energy?

A

We are the people who are using most of it

84
Q

What have workplaces done to try to reduce CO2?

A

They are using cleaner, more efficient technology.

85
Q

What is the implication of importing cheap goods?

A

They may have been made with polluting and inefficient technology

86
Q

How can we secure our energy supply for the future?

A

Replace old power station with more efficient ones; use a mix of renewable energy sources; use more renewable energy sources as fossil fuels run out.

87
Q

How much electricity do we need to be able to generate?

A

Enough to avoid power cuts caused by excess consumer demand.

Physics 21st Century (8 decks)

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