How electricity is generated

Turbine generator Diagram of a turbine generator - Spinning rotor turning coiled copper wir inside stationary magnets to generate electricity.

Source: Adapted from Energy for Keeps (public domain)

In 1831, scientist Michael Faraday discovered that when a magnet is moved inside a coil of wire, an electric current flows in the wire. An electricity generator is a device that converts a form of energy into electricity. Generators operate because of the relationship between magnetism and electricity. Generators that convert kinetic (mechanical) energy into electrical energy produce nearly all of the electricity that consumers use.

A common method of producing electricity is from generators with an electromagnet—a magnet produced by electricity—not a traditional magnet. The generator has a series of insulated coils of wire that form a stationary cylinder. This cylinder surrounds a rotary electromagnetic shaft. When the electromagnetic shaft rotates, it induces a small electric current in each section of the wire coil. Each section of the wire coil becomes a small, separate electric conductor. The small currents of the individual sections combine to form one large current. This current is the electricity that moves through power lines from generators to consumers.

An electric power plant uses a turbine or similar machine to drive these types of generators. Different types of turbines include steam turbines, gas combustion turbines, water turbines, and wind turbines.

A turbine converts the kinetic energy of a moving fluid (liquid or gas) to mechanical energy. In a turbine generator, a moving fluid pushes a series of blades mounted on a shaft, which rotates the shaft connected to a generator. The generator, in turn, converts the mechanical energy to electrical energy based on the relationship between magnetism and electricity.

In 2016, about 65% of total U.S. electricity generation was from steam turbines that use biomass, coal, geothermal energy, natural gas, nuclear energy, and solar thermal energy. These types of power plants are about 33% efficient, which means that for every 100 units of primary heat energy that goes into a power plant, only 33 units are converted to useable electrical energy.

Other types of devices that generate or produce electricity include electrochemical batteries, fuel cells, solar photovoltaic cells, and thermoelectric generators.