power grid

July 24, 2023

Pavle Ignjatović

How do we get electricity?

Life in the modern world can not be imagined without phones, internet, lightbulbs and many other things we use on a daily basis, and all of them have one thing in common - they need electricity. Let's see the path of that power on its way to us.

Generation

The first step of this process is creating electricity. As energy cannot be created or destroyed (First law of thermodynamics), another form of energy has to be transformed into electric power. This is done in power plants. Since it is too expensive to store large amounts of electricity, almost all of the power we use is created moments ago, potentially thousands of kilometers away. Therefore, one of the biggest challenges is instantly meeting a frequently changing demand of the grid.
To do this, different energy sources are layered on top of each other, ones on the bottom being those which are not designed to turn on and off quickly, and ones at the top being those that can connect to grid in minutes. That bottom layer are usually nuclear combined with coal power plants. Together, they fulfill a base-load, minimum amount of energy needed during the day. When the demand exceeds base-load, other sources are activated. These sources are ones in the top layer, easy to switch on when needed, usually gas-powered and hydroelectric plants.
Of course, renewable sources of energy (like solar and wind plants) are also in use, but due to their unreliability, they are mostly used in places where storage units can be profitable.
dam

Hydroelectric dam.

Transmission

Once energy is generated, it needs to be delivered to consumers. Due to the high cost of construction, not every part of country has its own power plant. That means that the energy has to be transmitted to further distances, converting itself to heat along the way. To lower this loss as much as possible, energy is converted to higher voltage in transformers. Along the way, this hight-voltage power encounters several substations, each time lowering voltage and getting closer to its destination. Finally, when voltage is around 220V, it gets to our homes.