Large power grids are among the most complicated machines humans have ever devised. Different generators produce power at various times and at various costs. A generator might fail and another fills the gap. Demand soars in the evenings and on hot days. In Australia, eastern and southern states trade power across borders. Meanwhile, Western Australia has two grids and the Northern Territory has several.
But these complicated machines are undergoing major change, as we shift from large fossil fuel plants to cleaner forms of power. Wind and sun are now the cheapest way to produce electricity. These renewable sources will soon overtake coal and gas – they’re already averaging 40% of power flowing through the national grid.
Solar and wind are often called “variable” renewable energy sources. Variable, here, refers to the fact the sun doesn’t always shine and the wind doesn’t always blow. On sunny, windy days we get lots of cheap power. But on still nights, we might get little.
