Sources of Electricity

Learning Objectives

Describe how a turbine and generator work together to produce electricity.

Explain that most electricity is generated by spinning a turbine, and the only difference is the energy source used to spin it.

Identify various energy sources used in power plants, including fossil fuels, nuclear, hydro, wind, and geothermal.

Making Electricity: It's All About the Spin

We use electricity for almost everything, but where does it come from? How is it made? While there are many different types of power plants, the vast majority of them use the same basic, two-step process to generate electricity.

Step 1: Spin a Turbine

A turbine is a machine with blades that looks like a very complex fan or a pinwheel. When a force pushes on the blades, it causes the turbine to spin at a very high speed. The key to generating electricity is finding a way to make a turbine spin.

Step 2: Turn a Generator

The spinning turbine is connected by a shaft to a generator. A generator is a device that converts mechanical energy (the spinning motion) into electrical energy. It works using a principle called electromagnetic induction. Inside the generator, the spinning shaft turns giant magnets inside coils of copper wire. The moving magnetic field pushes the electrons in the wires, causing them to flow. This flow of electrons is an electric current.

So, the basic recipe for making electricity is:

Spin a Turbine → Turn a Generator → Electricity!

What Makes the Turbine Spin?

The main difference between most power plants is what they use as the energy source to spin the turbine.

Fossil Fuel Power Plants (Coal, Natural Gas, Oil): These plants burn fossil fuels to heat water into high-pressure steam. The powerful steam is then used to blast against the blades of a steam turbine, making it spin.

Nuclear Power Plants: These plants use the heat from a nuclear fission reaction (splitting uranium atoms) to boil water into steam. This steam then spins a turbine.

Hydropower (Hydroelectric) Plants: These plants use the force of moving water. A dam holds back a river to create a reservoir. When the water is released, it flows down through a large tube and pushes against the blades of a water turbine.

Wind Power Plants: These use the force of the wind. The wind pushes against the large blades of a wind turbine, causing them to spin directly.

Geothermal Power Plants: These plants use steam from deep inside the Earth. Hot magma underground heats water into steam, which is then piped to the surface to spin a turbine.

Notice the pattern? Fossil fuels, nuclear, and geothermal all use steam to spin a turbine. Hydropower uses moving water. Wind power uses moving air. The end result is the same: a spinning turbine turns a generator.

The Exception: Solar Panels

Photovoltaic (PV) solar panels are a major exception to this rule. They do not use turbines or generators. Instead, they use special semiconductor materials to convert sunlight directly into electricity in a single step.

Key Terms

**Turbine: A machine for producing continuous power in which a wheel or rotor, typically fitted with vanes, is made to revolve by a fast-moving flow of water, steam, gas, air, or other fluid.
**Generator: A machine that converts mechanical energy into electrical energy, usually by rotating a magnet within a coil of wire.
**Electromagnetic Induction: The production of an electric current in a conductor by a changing magnetic field.
**Steam: The vapor into which water is converted when heated, forming a white mist of minute water droplets in the air.
**Fossil Fuels: A natural fuel such as coal, oil, or natural gas, formed in the geological past from the remains of living organisms.