The power grid

​Turning on the light is easy. Flip a switch, and electric current runs to the light bulb. But where does it come from? This is a power plant. Coal is used here to generate electricity.

The coal is burned, the heat boils water, turning it into steam, which drives the turbine of a generator, creating electricity. Here, chemical energy turns to heat, then to kinetic energy, and finally to electrical energy. The electric current is then passed out of the power plant through the power lines, all the way to Lena's house, where the electrical energy is turned into light. ​When electrical power is transmitted through a conductor, some of the energy is lost to the air as heat. This is a problem, especially at low voltages. Higher voltage leads to lower transmission losses.

So before transmitting the power, the voltage is increased to thousands of volts in a transformer station. But that voltage is too high for home use. So another transformer station is needed at the other end too, reducing the voltage back. ​Lena's neighbor is also connected to the power line, using the electrical energy from it-- and she uses a lot. But electricity costs money, and in order to keep track of how much they should pay, each of them is given a meter. Now they can get individual electricity bills, and only pay for what they have used. ​Here's a factory.

The machinery they use requires a higher voltage than a normal household does. So another transformer station is built, which converts power to a higher voltage for industrial use. Business is good, and the factory is running at full production. Now there is barely enough energy available from the power plant during daytime. But the night usage is low, and there is more power available than needed.

So why not store some of the power during the night, and use it the next day? Well, storing large amounts of electrical energy is both difficult and expensive, so electricity has to be generated at the same time it is being used. More people move in, connecting to the power supply. More power lines and transformer stations are installed in a network covering the town, a power grid. ​Now the power plant can't keep up with the demand for electricity. From household, to businesses, and industries.

So here comes another power company. They choose a different source of energy, the wind. The wind blows on the turbines, and as they spin, they convert kinetic energy into electrical energy. On a windy day, the wind turbines produce more power, and when the wind dies out, the coal power plant speeds up its production. This way the power grid gets a constant supply of electricity. ​A coal power plant can generate a lot of power at a low cost, but when the coal has been burned, pollutants get into the atmosphere, harming nature and contributing to climate change.

A nice thing about wind power is that there's no air pollution from wind turbines. Also, nature never runs out of wind. It's a renewable source of energy, but the wind turbines don't generate nearly as much power as the coal power plant, and building more of them is expensive. And of course, they only generate power when the wind is blowing. There are many things to consider when choosing what kind of power plant to build next.

Next time you turn on the light, think about how the electricity got all the way from a power plant, through the grid, and to your light bulb.