Unit 4: (d) Energy Resources and Electricity Generation

What is an energy resource?

A source of energy that can be used to generate electricity or provide useful energy.

What is the difference between renewable and non-renewable energy resources?

Renewable resources are naturally replaced and will not run out; non-renewable resources are finite and will eventually run out.

Name the renewable energy resources required for IGCSE.

Wind, water, geothermal, solar heating and solar cells.

Name the non-renewable energy resources required for IGCSE.

Fossil fuels and nuclear power.

What is the general energy transfer in electricity generation?

Energy from a resource is transferred into kinetic energy in a turbine, then into electrical energy by a generator.

How does a generator produce electricity?

A rotating turbine turns a generator, which transfers kinetic energy into electrical energy.

Describe the energy transfers in wind power generation.

Kinetic energy store of moving air is transferred mechanically to turbine blades; the generator transfers this into electrical energy.

What is the energy source in wind power?

The kinetic energy of moving air.

What is the role of the turbine in a wind power station?

The turbine converts the kinetic energy of wind into rotational kinetic energy.

What is the advantage of wind power?

It is renewable and produces no greenhouse gases during operation.

What is a disadvantage of wind power?

It is unreliable because wind speed changes.

Why is wind power unsuitable for constant electricity demand?

The wind does not always blow at the required speed.

Describe the energy transfers in hydroelectric power.

Gravitational potential energy of stored water is transferred to kinetic energy as water falls, then mechanical energy in turbines and finally electrical energy.

What is the energy source in hydroelectric power?

The gravitational potential energy store of water.

Why is water stored behind a dam useful?

It gives the water a high gravitational potential energy store.

What is an advantage of hydroelectric power?

It is renewable and can produce large amounts of electricity reliably.

What is a disadvantage of hydroelectric power?

Building dams is expensive and can destroy habitats.

Why can hydroelectric power respond quickly to changes in electricity demand?

Water flow through turbines can be controlled.

Describe the energy transfers in geothermal electricity generation.

Thermal energy from hot rocks heats water; steam transfers kinetic energy to turbines, which generate electricity.

What is the energy source in geothermal power?

Thermal energy from inside the Earth.

What is an advantage of geothermal energy?

It provides a reliable renewable energy source.

What is a disadvantage of geothermal energy?

It is only possible in areas with suitable geological conditions.

Describe the energy transfers in solar heating systems.

Light radiation from the Sun is absorbed and transferred into thermal energy in water or another fluid.

What is the purpose of solar heating systems?

To heat water or buildings using energy from sunlight.

What is an advantage of solar heating?

It uses a renewable energy source and produces no emissions during operation.

What is a disadvantage of solar heating?

It is less effective when sunlight levels are low.

Describe the energy transfers in solar cells.

Light energy from the Sun is transferred directly into electrical energy by photovoltaic cells.

What is the energy source in solar cells?

Light radiation from the Sun.

What is the difference between solar heating and solar cells?

Solar heating converts light energy into thermal energy; solar cells convert light energy directly into electrical energy.

What is an advantage of solar cells?

They are renewable and produce electricity without burning fuel.

What is a disadvantage of solar cells?

They produce less electricity at night or during cloudy weather.

Why are solar cells suitable for remote locations?

They can generate electricity without needing connection to a national grid.

Describe the energy transfers in fossil fuel power stations.

Chemical energy store of fuel is transferred to thermal energy by burning; thermal energy produces steam; steam turns turbines; generators transfer kinetic energy into electrical energy.

What are examples of fossil fuels?

Coal, oil and natural gas.

What is the energy source in fossil fuels?

The chemical energy store of the fuel.

What is an advantage of fossil fuel power stations?

They can generate large amounts of electricity reliably.

What is the main disadvantage of fossil fuels?

Burning them releases carbon dioxide, contributing to climate change.

Why are fossil fuels non-renewable?

They take millions of years to form and are used much faster than they are replaced.

What pollutants can fossil fuel power stations produce?

Carbon dioxide, sulfur dioxide and particulates.

Describe the energy transfers in nuclear power stations.

Nuclear energy store is transferred into thermal energy during fission; thermal energy produces steam; turbines and generators produce electricity.

What fuel is commonly used in nuclear power stations?

Uranium.

What happens during nuclear fission?

A large nucleus splits into smaller nuclei, releasing energy.

What is the energy source in nuclear power?

The nuclear energy store of uranium atoms.

What is an advantage of nuclear power?

It produces large amounts of electricity and releases very little carbon dioxide during operation.

What is a disadvantage of nuclear power?

It produces radioactive waste that must be stored safely.

Why is nuclear power considered non-renewable?

The fuel used is finite and cannot be replaced quickly.

What factors should be considered when choosing an electricity generation method?

Cost, reliability, environmental impact, availability of resources and amount of electricity produced.

Why is reliability important for electricity generation?

Electricity demand is continuous and supply must match demand.

Why are renewable resources called sustainable?

They use resources that are naturally replaced.

Why can renewable resources still have disadvantages?

They may be unreliable, expensive to build or have environmental impacts.

Compare wind power and fossil fuels.

Wind is renewable and produces no carbon dioxide during operation but is unreliable; fossil fuels are reliable but release greenhouse gases.

Compare nuclear power and fossil fuels.

Both provide reliable large-scale electricity, but nuclear produces radioactive waste while fossil fuels produce carbon dioxide.

Compare solar cells and fossil fuels.

Solar cells are renewable and clean during operation but depend on sunlight; fossil fuels are reliable but polluting.

Why might a country use a mixture of energy resources?

To balance reliability, cost, environmental impact and energy security.

Why is no energy resource perfect?

Each method has advantages and disadvantages involving cost, reliability and environmental effects.

What is energy security?

Having a reliable supply of energy to meet demand.

Why can renewable energy improve energy security?

It reduces dependence on limited fossil fuel supplies.

Why are fossil fuels still widely used?

They provide reliable large-scale electricity and existing infrastructure is already available.

Why is nuclear power useful for base-load electricity?

It can generate a constant large output over long periods.

What is base-load electricity?

The minimum continuous level of electricity demand that must always be supplied.

Why are wind and solar called intermittent energy sources?

Their output depends on weather conditions.

Why are backup power stations needed with some renewables?

To provide electricity when renewable sources cannot generate enough power.

Why do fossil fuels contribute to global warming?

Burning them releases carbon dioxide, a greenhouse gas.

Why does carbon dioxide affect climate?

It traps infrared radiation in the atmosphere, increasing global temperatures.

Why is radioactive waste a problem?

It remains hazardous for long periods and requires secure storage.

Why are renewable energy sources better environmentally?

They generally produce little or no greenhouse gases during operation.

Why can renewable energy sources still damage the environment?

Construction can affect landscapes, habitats and ecosystems.

How does a wind turbine generate electricity?

Wind rotates blades, blades turn a generator, and the generator produces electrical energy.

How does a hydroelectric turbine generate electricity?

Falling water rotates turbines connected to generators.

How does a fossil fuel turbine generate electricity?

Steam produced from burning fuel rotates turbines connected to generators.

How does a nuclear turbine generate electricity?

Heat from nuclear fission produces steam that rotates turbines.

How can the efficiency of electricity generation be improved?

Reduce unwanted energy transfers, improve turbine and generator designs, and reduce heat losses.