Most small generators are powered by fuels that are burned by the machine: diesel, biodiesel, gasoline, oil, or propane.
Larger, industrial generators are a bit different. These massive systems create the energy that powers the electrical grid. Because they need to produce such a large amount of energy, it’s inefficient for these systems to burn light-weight fuels.
Most power plants have historically been run on coal or crude oil. These fuels are burned to heat water to steam, which then rotates the generator system to create electrical energy. More recent attempts to incorporate renewable energy into electrical energy generation have led to the increased use of alternative fuel systems. Some of these systems still burn their fuel to create energy, as in the case of biomass (a collection of once-living things including wood, dead crops, and even garbage). Other renewable energy sources don’t need to burn anything to heat up steam: thermo energy uses the heat inside earth’s mantle to power energy production, and nuclear power plants use the energy stored within atoms to generate heat.
Some energy sources don’t require heat at all. Hydroelectric systems use moving water (found within rivers and ocean tides) to spin massive turbines connected to magnets. And wind turbines are spun by the movement of earth’s atmosphere; no fancy conversions required.
The Mechanics
Whatever the fuel used, the basic guts of a generator are the same and are based on the very first dynamo created by Michael Faraday. All generators move a magnet around a coil of wire, and that movement generates electrical energy. You can think of the motion of the magnet as “pushing” the electrons along, generating a flow of electrons known as an electric current. We harness that electrical current to power everything from our lights to our televisions.
The basic spinning magnet is the heart of a generator. The system can be scaled up or down according to one’s energy needs. Portable generators contain a small spinning magnet and a small coil of wire, while electrical generation plants have massive, superpowered magnets and huge coils of wire. And as we’ve already discussed in this article, you can make the magnet spin by either burning fuel, or harnessing something already in motion (water, wind, etc.)
The Output (Electrical Energy)
You probably already know that electrical generators, well, generate electricity. But the nitty-gritty of electricity is a bit more complicated. What exactly is electrical energy? And why is it so darn useful?
Electrical energy is one of the numerous types of energy found on earth. Energy is generally defined as the ability to do work, and electrical energy is no exception to that definition. We’ve found all sorts of different ways for energy to accomplish useful work for us: electric vehicles move us from one location to another, electric stovetops heat our food, and electric computers let us work online.
Even though electricity can seem almost magical in its ability to accomplish work, at its core, the basics behind electrical energy are relatively simple. You probably remember learning about the different parts of an atom in school: protons and neutrons make up the center, or nucleus of an atom, while subatomic particles called electrons orbit around the outside. While the nucleus of an atom is stuck tightly together, an atom’s electrons are free to move around. The motion of these electrons allows for all sorts of things, from chemical bonds to electrical energy.
The motion of electrons results in a type of kinetic energy (kinetic, from the Greek word kinetikos, meaning ‘of motion’). As electrons move around, they create what’s known as an electric current. Michael Faraday and subsequent scientists learned how to tap into that current of electricity and use it to power all sorts of things in our everyday lives.
Important Terminology
Whether you’re taking a physics class or looking to add an electrical generator to your home, there are a few terms you should know that might come in handy. Think of this as your electricity cheat sheet:
Electrical Energy
A type of energy caused by the motion of electrons. These electrons form an electric current, which powers most of modern life.
Joule
No, not like the crown jewels. A Joule (J) is the scientific unit of energy; more joules equals more energy.
Watt
Unless you’re a scientist, you’ll probably use Watts (W) to measure the energy around your house. You know how the lightbulb box says 5 watts? That’s a measure of how much energy that lightbulb uses each second. One watt is equal to one joule of energy used per second.
Watt-hours
This term will probably show up on your electrical bill. A watt-hour (Wh) shows how much energy something has used over a specific amount of time. Your electrical bill will likely be expressed in kilowatt hours, which is a unit of measurement 1000 times larger than a single watt-hour.
Circuit
You can think of a circuit as the circular path that electrons follow as they move in their electrical current. Circuits direct the electrical current and make it useful; everything in your home that uses electricity is part of a circuit.
Turbine
The part of a generator that spins is called a turbine. Depending on your fuel source, your generator might include a steam, gas, water, or wind turbine.
Efficiency: In the context of generators, efficiency is a measure of how effective a generator is at producing electricity. Some types of generators are more efficient than others, which means they’re better able to transform the energy of their fuel into electrical energy.
Alternating Current (AC)
An alternating current is one which changes direction. AC systems are often used in buildings because this type of energy can traverse long distances with relative ease.
Direct Current (DC): A current that doesn’t change direction. Many electrical systems utilize DC, and students often study DC electrical systems before tackling the more complex alternating currents.