Electricity is a very convenient form of energy that can be generated using different energy resources. Some of these resources are renewable and some are non-renewable. Each resource has advantages and disadvantages.

The fossil fuels are coal, oil and natural gas. They are fuels because they release heat energy when they are burned. They are fossil fuels because they were formed from the remains of living organisms millions of years ago.

About three-quarters of the electricity generated in the UK comes from power stations fuelled by fossil fuels. To the right is an energy transfer diagram for the generation of electricity from a fossil fuel such as coal.

Fossil fuels are non-renewable energy resources. Their supply is limited and they will eventually run out. Fossil fuels do not renew themselves, while fuels such as wood can be renewed endlessly.

Fossil fuels release carbon dioxide when they burn, which adds to the greenhouse effect and increases global warming. Of the three fossil fuels, for a given amount of energy released, coal produces the most carbon dioxide and natural gas produces the least.

Coal and oil release sulfur dioxide gas when they burn, which causes breathing problems for living creatures and contributes to acid rain.

Uranium and plutonium

The main nuclear fuels are uranium and plutonium. These are radioactive metals. Nuclear fuels are not burnt to release energy. Instead, the fuels are involved in nuclear reactions in the nuclear reactor, which leads to heat being released.

The rest of the process of generating electricity is then identical to the process using . The heat energy is used to boil water. The kinetic energy in the expanding steam spins turbines, which then drive generators to produce electricity.

Advantages

Unlike fossil fuels,  do not produce carbon dioxide or sulfur dioxide.

Disadvantages

Like fossil fuels, nuclear fuels are non-renewable energy resources. If there is an accident, large amounts of radioactive material could be released into the environment. In addition, nuclear waste remains radioactive and is hazardous to health for thousands of years. It must be stored safely.

You should be able to outline how electricity is generated using wind energy.

Big convection currents

The wind is produced as a result of giant convection currents in the Earth's atmosphere, which are driven by heat energy from the sun. This means that the kinetic energy in wind is a renewable energy resource: as long as the sun exists, the wind will too.

Wind turbines have huge blades mounted on a tall tower. The blades are connected to a nacelle or housing that contains gears linked to a generator. As the wind blows, it transfers some of its kinetic energy to the blades, which turn and drive the generator. Several wind turbines may be grouped together in windy locations to form wind farms.

Advantages

Wind is a renewable energy resource and there are no fuel costs. No harmful polluting gases are produced.

Disadvantages

Wind farms are noisy and may spoil the view for people living near them. The amount of electricity generated depends on the strength of the wind. If there is no wind, there is no electricity.