Below are some of the resources that can be used to generate electricity. Each resource has its own advantages and disadvantages
|
Resource |
Advantages |
Disadvantages |
| Fossil fuel power stations | Reliable source of energy | Start up time depends on the fuel being used (gas stations take the shortest time then oil followed by coal)Produce greenhouse gases which increase global warming |
| Nuclear power stations | Reliable source of energyRelatively cheap fuel | Long start up timeExpensive to dismantle old power stationsHard to store dangerous radioactive wasteAccidents tend to have catastrophic effects |
| Renewable sources | Fuel is freeTidal barrages and hydroelectric power are reliable sources | The equipment can be expensive to constructWind and solar energy are less reliable source |
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The National Grid
Energy reaches consumers via the National Grid. Electricity from power stations as well as other energy sources supplies the country with the electricity they require.
Transformers
The National Grid is composed of wires and cables and it’s through these that the electricity is transferred from the power stations.
The electricity is only allowed to flow at a low current to cut down the amount lost by heat (the higher the current, the higher the amount lost by heat). To achieve this a high voltage is required. The voltage is controlled by electrical devices called transformers. This is able to modify the voltage of an alternating current (AC) as found in the mains electrical supply. There are two types of transformer:
- step-up transformers increase voltage
- step-down transformers decrease voltage
The electricity from a power station is produced at 25,000 V. Step-up transformers increase the voltage to the amount required to travel through the power lines of the National Grid, either 132,000 V, 275,000 V or 400,000 V. Heat loss is reduced but these values are much too high for a home. Step-down transformers then reduce the voltage to around 230 V, a safe level for consumer use.