Making Electricity

Before delving into the details of different electricity sources I’m going to give a basic overview of how the electricity that comes to your home is made. Despite the fact that I’d been studying physics, before I toured a hydroelectric plant in Tanzania I only had a theoretical understanding of how we actually make electricity at a power plant. I was fascinated on the plant tour, and count that among the defining moments in inspiring me to want to study and work with renewable energy.

So to start: what is electricity? It’s moving electrons. Typically we move the electrons in metal wires because metals tend to have plenty of free electrons just hanging around ready to move, and also plenty of spaces for the electrons to move into.

How do we convince these electrons to move? Electrons will start moving in the wires when there is a moving magnetic field nearby. In a typical coal or natural gas fueled power plant, the fuel is used to move big magnets in order to produce a moving magnetic field.

The coal or natural gas (or sometimes petroleum, but not much in the U.S.) is burned in order to heat up water in pipes. As the water heats to a boil it changes into steam. The steam rises through the pipes until it gets to a condensation tank. Here it cools down and changes back into liquid water. The liquid water is heavy, so it falls to the bottom of the tank, and as it does this it turns a turbine. The liquid water is then pumped back to the furnace where it can be heated up again.

The turbine is connected to a big magnet inside of a large coil of wire. When the turbine spins from the condensing water, it turns the magnet which produces a moving magnetic field, and the moving magnetic field causes all those free electrons in the wire coil to move throughout the wire.

For each source of electricity (except solar, we’ll get to that later), the objective is to spin that magnet inside the coil of wires.