New to Climate Change?

Nuclear Energy

Nuclear energy is energy made by breaking the bonds that hold particles together inside an atom, a process called “nuclear fission.” This energy is “carbon-free,” meaning that like wind and solar, it does not directly produce carbon dioxide (CO2) or other greenhouse gases that contribute to climate change. In the U.S., nuclear power provides more than half of our carbon-free electricity.

Because the nuclear bonds inside atoms hold so much energy, nuclear power plants can make more energy with less fuel than any other technology today. In fact, nuclear power could meet the average American’s lifetime energy needs with an amount of fuel that would fit in a soda can.

How It Works

Some atoms, like uranium-235 and plutonium-239, are prone to breaking apart when collided with particles called neutrons. In a nuclear power plant, a fuel with high concentrations of these atoms is placed in a secure device called a nuclear reactor. Here, free neutrons circulate until the fuel absorbs them, which triggers the atoms to split. When the atoms split, they release more neutrons, so more and more atoms split in a chain reaction. The massive energy released by this nuclear fission makes the reactor incredibly hot.

Usually, this heat is used to boil water and turn a turbine, making electricity.

Nuclear power uses very little fuel. A uranium fuel pellet the size of your finger can produce as much energy as one ton of coal or 17,000 cubic feet of natural gas. Because nuclear fuel is not burned like coal or gas, the same amount of fuel that goes into a reactor comes out after the fuel is used. This spent fuel will be radioactive for thousands of years, and can be harmful to people or the environment, so managing it is one of the biggest challenges of nuclear power, just as the air pollution from fossil fuels and the electronic waste from solar panels are serious challenges for other forms of energy. Practical solutions for disposal, recycling and reuse of spent nuclear fuel already exist, and others are being studied. To be effective, these solutions must be backed by policy choices and popular approval.

Nuclear Energy in a Carbon-Free Energy System

Nuclear energy meets important needs that other carbon-free energy sources cannot yet match. Unlike wind or solar power, nuclear power does not depend on the weather, so it can make electricity exactly when we need it. Most nuclear plants are built to make huge amounts of energy day in and day out, providing the “baseload” power we need at all times. Some newer designs are instead meant to turn on and off quickly, providing the “dispatchable” power we need when demand for energy is highest.

Nuclear energy is also a good carbon-free source of heat. In the future, this heat could be used for industrial processes like making concrete and steel, which we cannot accomplish with the electricity from solar, wind or hydropower.

These factors mean that nuclear energy is a much more direct substitute for fossil fuels than other low-carbon energy sources. On the other hand, nuclear plants are more expensive to build than solar or wind farms, especially at a small scale. As we phase out the fossil fuels driving climate change, nuclear power would be most effective as part of a low-carbon energy mix.


Published October 14, 2020.

Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International license (CC BY-NC-SA 4.0).
Photo Credit
The International Atomic Energy Agency via Flickr