Blog Post Wednesday 06 December 2017
From flipping on the light switch and turning on your phone to reheating a snack in the microwave, the everyday activities we take for granted utilise an essential energy source – electricity. Now that you stop and think about it, you might wonder how this power arrives at your home from once it’s been generated. As we’ll outline here, the electricity we take for granted makes a long journey from the power station to your home. So, here’s how it gets delivered to you...
Australia’s electricity grid spans more than 4,500 kilometres, and that’s just the eastern and southern states. Western Australia, the Northern Territory, and Mount Isa in Queensland have individual transmission and distribution networks. With more than 40,000 km of transmission lines, the main electricity grid includes transmission and distribution elements that allow transportation across the vast distances to your home. Australia’s grid is relatively efficient, with an average of 5% of electricity lost through the transmission and distribution process. This is a relatively low figure compared to loss rates for other countries.
Electricity starts its life in a power station. Power stations are huge plants – often located near energy sources like natural gas plants, hydroelectricity dams, and solar or wind farms – that produce electricity. Depending on the type of fuel or source of energy input - whether it’s coal, solar, wind, or even nuclear - power plants may have components such as a furnace, boiler, turbine, cooling towers, and generators. These types of components are essential for the generation process.
Once the electricity is generated, it leaves the power station through overhead lines to large substations. At this stage, the electricity can be at as high as 25,000 volts or ever higher.
Substations are usually located near power stations. Substations play an important role in the electricity transmission process: they further increase the voltage of the current, allowing it to be sent over long distances without losing too much power. Substations do this by using transformers, and these can be used to either increase or decrease the voltage of electric currents. Decreasing the voltage of electricity can be important at distribution substations as it needs to be made less powerful and safe before it enters your house.
Once it passes through the first substation transformer, your electricity makes its way to the transmission networks.
The transmission networks help shift electricity from power stations on to distribution networks to facilitate delivery to households, businesses, and other end users. At this stage, the electricity remains at a high voltage since it still needs to move across vast distances.
The transmission networks are made up of overhead lines on metal pylons or lines buried under the ground. These lines are designed to carry ultra-high voltages and they’re insulated to prevent the electric current from accidentally moving to the ground, where it can be dangerous for people.
At the second substation transformer point, your electricity is reduced in voltage, again through the use of transformers, to make it safe for use by households and end users. At this point the electricity is considered to have reached the distribution network and left the transmission network.
The type of substation and voltage can vary depending on the use and location. For example, in rural areas, smaller substations might be used to reduce the voltage to around 33,000 volts, which makes it suitable for powering trains and factories. In urban areas with factories, the voltage could range between 11,000 and 33,000 volts to serve smaller factories. Contrast with delivery to homes, offices, and business, where the neighbourhood transformer might lower the voltage to as little as 230 volts.
Once your electricity leaves the substation transformer, it enters distribution power lines on its way to the final destination. Power lines can be overhead or underground, and they’re a familiar sight in most areas around Australia. Once it reaches your neighbourhood, the electricity passes through a small pole-top transformer for another voltage reduction. This ensures it’s safe to use inside the home, office, or business.
Your electricity passes through the service drop and gets recorded at your metre. The metre tracks how much electricity you use. At your switchboard, your electricity gets divided up into circuits for each area of your house. Finally, the electricity moves through wires behind your walls to power outlets and switches, where you operate your lights and appliances.
It’s easy to take the electricity used to light your house for granted, but this precious energy source has travelled a long way, through complex generation and transmission infrastructure, to get to your house. Knowing this, you’re probably less likely to take electricity for granted when you next switch on your light or power up the TV.