Plumes of smoke rising from a nuclear power plant

How is Electricity Generated, Anyway?

gabriel colon reyes

Have you ever wondered what exactly electricity is? Think about it for a minute. We use electricity to turn on the lights, charge our phones, and participate in a wide variety of activities. But where exactly does electricity come from?

In simple terms, electricity is the result of interactions between electrons–negatively charged particles–that result in energy. But energy is converted from one form to another. So in order to get electricity at our homes and workplaces, energy needs to exist in some other form in nature and then be converted into its electrical form.

There are three main types of energy that are converted to electricity: thermal energy, coming from heat; kinetic energy, coming from the motion of fluids; and luminal energy, coming from light.

Thermal Energy

Coal, natural gas, and petroleum are fossil fuels. These sources of chemical energy are formed from the fossils of once living organisms such as plants and animals. They are considered nonrenewable because the process through which dead organisms are converted under high pressure and heat to fossil fuels can take millions of years. Uranium and plutonium are nuclear fuels, also nonrenewable sources, and sources of nuclear energy

What’s common in all these thermal energy sources is that they are used as fuel to heat water and produce energy in the form of heat, hence the name. In reality, this heat is high-pressure steam, which spins a turbine that then spins a generator, creating electricity. This video on electricity generation describes that chemical process, while this video on nuclear power plants describes the process for nuclear energy, which differs from that of other nonrenewable resources.

Steam power plant
Water is converted into steam from heat produced in a nuclear reactor core. Credit: Alexandra Beier/Getty Images

Kinetic Energy

The motion of fluids, such as water and air, is a naturally occurring source of kinetic energy. Wind, waves, and hydropower plants are examples of this. Wind and wave energy are usually considered renewable energy sources because they naturally exist in abundance. In contrast, hydropower is usually considered an energy storage method as it requires excess electricity to pump water up to a reservoir, and then it can be brought down to be converted back to electricity. 

A turbine is a fundamental component of kinetic energy conversion. This machine captures kinetic energy, converts it into rotational energy via a shaft, then feeds it into a generator to generate electricity. The kinetic energy of moving fluids can be captured and converted to rotational kinetic energy using a wind turbine. The wind turbine’s blades spin a shaft, which feeds a generator that converts the energy into electricity.

Wind turbines in an open field
A wind turbine’s spinning motion is an example of kinetic energy. Credit: Thomas Reaubourg/Unsplash

Light Energy

Light is a renewable energy source because it naturally exists in abundance and is readily available. Luminal energy can be directly converted into electricity using materials with specific energy conversion properties called semiconductor materials. Specifically, these materials can be arranged in arrays to form photovoltaic panels that convert light energy into electricity.

Electricity and the Grid

Now that we’ve discussed how energy is converted to electricity, it is worth briefly mentioning how this affects the technical operation of the electric grid. Both renewable and nonrenewable energy sources have the same end result: they both produce electricity. However, the processes by which they do so can vary greatly. For instance, the physical interactions that occur between machines and devices to produce electricity from thermal, kinetic, and luminal sources are different. With more renewable energy sources being incorporated into the grid each year, these physics are changing and require that we know how to operate them properly to ensure the same level of reliability we would expect from the fossil fuel-powered grid we’re used to.

Cover image credit: Sean Gallup/Getty Images

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