Electricity is a very convenient form of energy that can be generated using different energy resources
Non - Renewable resources
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.
Disadvantages of Fossil Fuels
Fossil fuels are non-renewable energy resources. Their supply is limited and they will eventually run out.
Fossil fuels release carbon dioxide when they burn, which adds to the greenhouse effect and increases global warming. Coal produces the most carbon dioxide and natural gas produces the least.
Coal and oil release sulphur 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. The fuels are involved in nuclear reactions in the nuclear reactor, which leads to heat being released. The heat energy is used to boil water. The kinetic energy in the expanding steam spins turbines, which then drive generators to produce electricity.
Do not produce carbon dioxide or sulphur dioxide.
Nuclear fuels are non-renewable energy resources. If there is an accident, large amounts of radioactive material could be released into the environment. Nuclear waste remains radioactive and is hazardous to health for thousands of years and it must be stored safely.
The wind is produced as a result of giant convention 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.
Wind turbines have huge blades mounted on a tall tower. The blades are connected and are 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.
Wind is a renewable energy resource and there are no fuel costs. No harmful polluting gases are produced.
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.
The water in the sea rises and falls because of waves on the surface. Wave machines use the kinetic energy in this movement to drive electricity generators.
Huge amounts of water move in and out of river mouths. A tidal barrage is a barrier built over a river estuary to make use of the kinetic energy in the moving water. The barrage contains electricity generators, which are driven by the water rushing through tubes in the barrage.
Hydroelectric power (HEP)
hydroelectric power stations use the kinetic energy in moving water.The water comes from behind a dam built across a river valley. The water high up behind the dam contains GPE This is transferred to kinetic energy as the water rushes down through tubes inside the dam. The moving water drives electrical generators, which may be built inside the dam.
Is a renewable energy resource and there are no fuel costs. No harmful polluting gases are produced. Tidal barrages and hydroelectric power stations are very reliable and can be turned on quickly.
Difficult to scale up the designs for wave machines to produce large amounts of electricity. Tidal barrages destroy the habitat of estuary species. Hydroelectricity dams flood farmland and push people from their homes. The rotting vegetation underwater releases methane, which is a greenhouse gas.
Several types of rock contain radioactive substances such as uranium. Radioactive decay of these substances releases heat energy, which warms up the rocks. In volcanic areas, the rocks may heat water so that it rises to the surface naturally as hot water and steam. The steam can be used to drive turbines and electricity generators.
In some places, the rocks are hot, but no hot water or steam rises to the surface. Deep wells can be drilled down to the hot rocks and cold water pumped down. The water runs through and is heated up. It returns to the surface as hot water and steam, where its used to drive turbines and electricity generators.
Is a renewable energy resource and no fuel costs. No harmful polluting gases are produced.
Most parts of the world do not have suitable areas where geothermal energy can be exploited.
Devices that convert light energy directly into electrical energy. Larger arrays of solar cells are used to power road signs in remote areas.
Solar panels do not generate electricity,they heat up water. Located on the roofs of buildings where they receive heat energy from the sun.
Cold water is pumped up to the solar panel, there it heats up and is transferred to a storage tank.
A pump pushes cold water from the storage tank through pipes in the solar panel. The water is heated by heat energy from the sun and returns to the tank. a conventional boiler may be used to increase the temperature of the water.
Solar energy is a renewable energy resource and there are no fuel costs. No harmful polluting gases are produced.
· Solar cells are expensive and inefficient, so the cost of their electricity is high.
· Solar panels may only produce very hot water in very sunny climates, and in cooler areas may need to be supplemented with a conventional boiler.
· Although warm water can be produced even on cloudy days, neither solar cells nor solar panels work at night.
Power stations fuelled by fossil fuels or nuclear fuels are reliable sources of energy. they can provide power whenever it is needed.
Their start-up times vary according to the type of fuel used.
1. gas-fired station (shortest start-up time)
2. oil-fired station
3. coal-fired station
4. nuclear power station (longest start-up time)