National Grid

• Electricity in the UK is generated from a range of sources, with most coming from power stations
• Power stations work by generating heat and converting it into electrical energy
• Electricity demand peaks in the late afternoon and evening when people are cooking and watching TV
• Power stations need to have lots of spare capacity to cope with surges in demand
• The national grid transmits huge amounts of power across the country
• Power is equal to voltage times current
• To minimize energy loss during transmission, high voltage is used to keep current low
• Step up transformers increase the voltage to around 400,000 volts before transmitting electricity across the country
• Step down transformers lower the voltage to around 230 volts before reaching its destination like a town
• Lowering the voltage is important because high voltages are dangerous and can damage appliances
• Electricity distribution by the National Grid:

  • Electricity in the UK comes from burning fossil fuels (50%), renewables like wind power (25%), nuclear power (20%), and imports from Europe
  • National Grid delivers electricity from power stations to around 25 million homes in the UK
  • National Grid consists of transformers and high-voltage cables
• Energy loss in power cables:

  • Energy is lost in power cables due to wire resistance
  • Greater distance between power station and homes leads to greater energy loss
  • Energy loss can be reduced by building power stations near homes or using transformers
• Role of step-up transformers:

  • Step-up transformers increase potential difference to several hundred thousand volts
  • Higher potential difference reduces energy loss in transmission cables
• Role of step-down transformers:

  • Step-down transformers reduce potential difference to around 230 volts
  • This reduced potential difference allows electricity to be safely passed into homes
• The National Grid is a network of transformers, pylons, and transmission cables that distribute electricity to homes, schools, offices, and factories across the United Kingdom and Ireland
• Power stations generate electricity with an alternating potential difference of 25,000 volts
• Step-up transformers increase the potential difference from 25,000 volts to 400,000 volts
• Pylons and transmission cables transfer the electricity over long distances
• Step-down transformers decrease the potential difference from 400,000 volts to 230 volts for homes and schools
• Factories receive a potential difference of either 100,000 volts or 33,000 volts
• Resistance in transmission cables heats up the wires, converting electrical energy into thermal energy
• Thermal energy dissipates into the surroundings, increasing the temperature of the air
• Using a higher potential difference of 400,000 volts is more efficient as less energy is wasted by heating