Nuclear Power Explained: All You Need to Know

Nuclear Power Explained: All You Need to Know

Grace Smoot

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Nuclear power has faced criticism for its use of radioactive materials to generate electricity. But the process produces little to no carbon dioxide (CO2) emissions or other greenhouse gasses (GHGs). So, we had to ask: What is nuclear power really, and how could it help us mitigate climate change?

Nuclear power is created through either nuclear fusion or nuclear fission. Per kWh produced, nuclear power emits 12 grams of CO2 on a life-cycle basis. It combats climate change and has various environmental benefits, but can come with the threat of nuclear waste products.

Keep reading to find out all about what nuclear power is, its global capacity, its carbon footprint, its environmental benefits and drawbacks, and how it can combat climate change.

The Big Picture of Nuclear Power

Nuclear power is the generation of energy via the process of nuclear fusion or nuclear fission, which produces little to no carbon dioxide (CO2) emissions or waste products. 

How Is Nuclear Power Defined

When it comes to nuclear power, we need to start with atoms. All matter consists of atoms, each of which contains a nucleus. A nucleus can either be joined to another nucleus or divided, both of which are processes that release energy in the form of heat.

“Nuclear Power: the power produced when the nucleus (= central part) of an atom is divided or joined to another nucleus”

Cambridge Dictionary

Because it is often described as an efficient, safe, and clean energy substitute for fossil fuels, understanding how nuclear power works and how its carbon emissions affect the global climate change process is important.

What nuclear power isNuclear power is generated when the nucleus of an atom is divided or joined to another nucleus.
How nuclear power worksThe energy created when neutrons either fuse or divide releases energy in the form of heat which produces steam, spins a turbine, and drives generators to produce electricity.  
The global capacity of nuclear powerApproximately 4% of global primary energy comes from nuclear power. Global distribution varies, with some countries producing no nuclear power and others sourcing most of their energy from nuclear power. An average yearly new nuclear capacity of 20 GW is required to achieve net zero by 2050.
The carbon footprint of nuclear powerOn a life-cycle basis, nuclear power emits 12 grams of CO2 equivalent per kilowatt-hour (kWh) of electricity produced.
The environmental benefits of nuclear powerNuclear power mitigates climate change, promotes energy independence, creates jobs, and improves air quality. It has minimal land use impacts and produces little to no waste products. 
The environmental drawbacks of nuclear powerUranium mining and radioactive wastes are drawbacks associated with nuclear fission.
Nuclear power and climate changeNuclear power combats climate change because it is a reliable, efficient, and low-carbon emission source of energy.

How Does Nuclear Power Work

In general, nuclear power is generated when neutrons either fuse or divide, which releases heat, produces steam, spins a turbine, and drives generators to produce electricity.  

How Does Nuclear Power Actually Produce Energy

The two ways to generate nuclear power are via nuclear fusion and nuclear fission.

Nuclear fusion is the process by which lighter atoms are combined or fused to create larger and heavier atoms. Nuclear fusion is still in the research and development phase. 

Illustration of the nuclear fusion process
International Atomic Energy Agency: Nuclear Fusion

Fusion reactions take place in plasma, a hot, charged gas made of positive ions and free-moving electrons. Deuterium and Tritium, isotopes of hydrogen with extra neutrons, are most commonly used as the fusion material. In theory, it is possible to produce a terajoule of energy, enough to meet the needs of an adult person living in the developed world for 60 years, with just a few grams each of Deuterium and Tritium. 

The sun and stars get their energy from nuclear fusion, as hydrogen atoms fuse together to form helium and matter converts into energy. However, this process is very hard to control within a laboratory setting. More still needs to be done to determine if this could be another viable energy source. 

Nuclear fission is the process by which neutrons are used to split the nucleus of a Uranium-235 atom, which releases an enormous amount of energy in the form of heat and radiation. Each time the reaction occurs, more neutrons are free to strike more and more nuclei, causing a chain reaction. All operating nuclear power plants today use the process of nuclear fission.

Illustration of the nuclear fission process
International Atomic Energy Agency: Nuclear Fission

The Uranium isotope used in fission is Uranium-235 (U-235) because its atoms are easily split apart in nuclear reactors. U-235 has a concentration of 2.8 parts per million (0.7% abundance) in Earth’s crust. Although it can be found almost everywhere supplies of U-235 are finite, and we have already used up most of it because it has a half-life of about 700 million years

What Is the Global Capacity of Nuclear Power

We have been generating nuclear power since the 1960s, but production really increased between 1970 and 1990. Production has since slowed significantly, although recent years have seen an uptick in production. 

Globally, the world generated 2,735 terawatt-hours (TWh) of electricity in 2021 from 439 nuclear reactors.  

Illustration of global generation of nuclear energy, 2021
Our World in Data: Global generation of nuclear energy

Some countries produce no nuclear power while others get the majority of their energy from nuclear power. For example, the US gets roughly 8% of its electricity from nuclear while France gets roughly 37% of its electricity from nuclear. 

Illustration of share of primary energy from nuclear, 2021
Our World in Data: Share of primary energy from nuclear, 2021

The top 5 nuclear power generating countries (amount produced per year) in the world are: 

  1. United States – 778 terawatt-hours (TWh)
  2. China – 407 TWh
  3. France – 379 TWh
  4. Russia – 222 TWh
  5. South Korea – 153 TWh

Approximately 4% of global primary energy comes from nuclear power. According to current trends and policy targets, nuclear capacity in 2040 will rise to 582 gigawatts (GW), which is still below the 812 GW required to become net zero by 2050. An average yearly new nuclear capacity of 20 GW is required to meet these net zero goals.

Estimates suggest that nuclear fusion alone could generate up to 4 times more energy per kilogram of fuel than fission and nearly 4 million times more energy than burning oil or coal. This is why research and development of nuclear fusion is crucial for its implementation.

What Is the Carbon Footprint of Nuclear Power

The carbon footprint is one of the ways we measure the effects of human-induced global climate change. It primarily focuses on the GHG emissions associated with consumption, but also includes other emissions such as methane (CH4), nitrous oxide, and chlorofluorocarbons.

Carbon footprint: the amount of greenhouse gasses and specifically carbon dioxide emitted by something (such as a person’s activities or a product’s manufacture and transport) during a given period”

Merriam Webster

Basically, it is the amount of carbon emitted by an activity or an organization. This includes GHG emissions from fuel that we burn directly (e.g., heating a home, driving a car) and GHG emissions from manufacturing the products that we use (e.g., power plants, factories, and landfills). 

On a life-cycle basis, nuclear power (nuclear fission) emits 12 grams of CO2 equivalent per kilowatt-hour (kWh) of electricity produced, which is tied for the third-lowest out of all energy types.

Have a look at the illustration below to see the average life-cycle CO2 equivalent emissions of the alternative energy sources and how they compare to the other energy types.

Illustration of CO2 equivalent per energy source
World Nuclear Association: Average life-cycle CO2 equivalent emissions

When discussing the carbon footprint of certain alternative energy types, we must take into account carbon emissions across the energy’s building, operating, and building back phases.

The life-cycle stages of nuclear powerEach stage’s carbon footprint
Building of nuclear powerSome CO2 emissions from constructing the nuclear power plant, mining and processing uranium, transporting nuclear fuel to the power plant
Operating of nuclear powerLittle to no CO2 emissions or waste products
Building back of nuclear powerSome CO2 emissions from transporting used fuel/radioactive material and deconstructing the power plant

Over the past 50 years, nuclear power has helped to avoid around 55 gigatons (Gt) of CO2 emissions, which is equal to nearly 2 years of global energy-related CO2 emissions

Illustration of cumulative CO2 emissions avoided by global nuclear power in selected countries, 1971-2018
International Energy Agency: Cumulative CO2 emissions avoided by global nuclear power in selected countries, 1971-2018

Because nuclear power has climate reduction benefits and produces little to no waste products, it is important to understand what its carbon footprint is. And how its carbon emissions affect the global climate change process.

Related: Are you interested in more about the carbon footprint of nuclear power? Check it out in this article here: “What Is the Carbon Footprint of Nuclear Power?

How Environmentally Friendly Is Nuclear Power

The overall environmental friendliness of nuclear power is a controversial topic. Although the process of nuclear fission produces zero CO2 emissions, the handling and disposal of nuclear waste is a serious issue. 

“Environmentally friendly: (of products) not harming the environment.”

Cambridge Dictionary

Nuclear power can reduce the effects of global warming by limiting global GHG emissions, but uranium mining and nuclear waste are drawbacks that must be taken into consideration.

What Are Environmental Benefits of Nuclear Power

Both nuclear fusion and nuclear fission provide the following environmental benefits:

  1. Protects air quality: Nuclear is a little to no-emission, clean energy source. Rather than combusting materials, the heat released by nuclear fusion and fission creates steam which spins turbines to generate electricity. 
  1. Climate change mitigation: Nuclear fusion produces no CO2 or other GHGs, and nuclear fission has an average life-cycle CO2 equivalent emission value that is much less than coal, 12g of CO2 equivalent per kWh compared to 820g of CO2 equivalent per kWh, respectively. This reduction in CO2 emissions, in turn, reduces the effects of global climate change including increasing temperatures, rising sea levels, melting of sea ice, changing precipitation patterns, and ocean acidification.
  1. Energy independence: Being able to produce our own electricity in the U.S. without the aid of foreign countries is an important step to help us become more self-sufficient. Former President George W. Bush signed the Energy Independence and Security Act of 2007 to reduce US dependence on oil, expand the production of renewable fuels (and confront global climate change). 
  1. Employment opportunities: The US directly employs about 100,000 people in the nuclear power sector. It takes 500-800 people to staff a power plant and up to 7,000 people to construct that plant. For every 100 jobs at the power plant, another 66 jobs are created in the local community. 

Nuclear fusion provides its own unique environmental benefits:

  1. Produces no CO2 or other GHGs: Nuclear fusion does not produce CO2 or other GHGs, therefore it does not contribute to global warming and climate change.
  1. Cannot cause a nuclear accident: Nuclear fusion cannot cause a nuclear accident because the process is not based on a chain reaction. The plasma must be kept at high temperatures and be confined by a magnetic field. Any change to the temperature or containment causes an immediate shutdown of the fusion reactor.
  1. Produces no nuclear waste: A nuclear fusion reactor produces helium (an inert gas) and produces and consumes tritium in a closed circuit. Although tritium is radioactive, its half life is very short and it is only used in low amounts so it does not pose serious danger.

And nuclear fission produces its own unique environmental benefits:

  1. Minimal land use impact: Nuclear power produces more electricity on less land than any other clean-air source. A standard, 1,000-megawatt facility located in the US requires a little more than 1 square mile to operate, a number that is 360 and 75 times less than what is required for wind farms and solar plants, respectively. 
  1. Few waste products: All of the used nuclear fuel that the US produced in the past 60 years could fit onto a football field at a depth of fewer than 10 yards. There are no other byproducts. 

What Are Environmental Drawbacks of Nuclear Power

The main drawback to nuclear fusion is that it is still in the research and development phase. Although it is capable of generating massive amounts of energy without releasing harmful GHGs or harming the environment, it is currently difficult to replicate this process on a commercial level in a laboratory setting. 

Nuclear fission on the other hand does come with some drawbacks that, if handled properly, can be mitigated. The main environmental drawbacks associated with nuclear fission are uranium mining and nuclear waste.

  • Uranium mining: This process contaminates the environment with radioactive dust, radon gas, water-borne toxins, and increased levels of background radiation. Exploratory drilling and mining also heavily increases the risk of water contamination. 
  • Nuclear waste: Although nuclear power produces minimal waste, the waste that it does produce is radioactive and can remain hazardous for many thousands of years. These radioactive waste products include uranium mill tailings, spent (used) reactor fuel, and other radioactive wastes. If these were to leach into the environment it could contaminate the soil and water.
  • Nuclear accidents: The nuclear fission process is based on a chain reaction, which, if it gets out of control, can release massive amounts of radiation into the surrounding area. There have been two major nuclear accidents worldwide, first at Chernobyl in 1986 and second at Fukushima in 2011. A power surge at Chernobyl damaged the nuclear core, which led to a steam explosion that spread radiation into the atmosphere. A tsunami that hit Fukushima caused flooding that disabled backup generators, leading to a failure in the cooling system. The core quickly overheated and caused a meltdown.

Ways to minimize negative environmental impacts include the proper handling, transportation, storage, and disposal of radioactive waste to ensure that it does not leach into the environment. 

Why Is Nuclear Power Important to Fight Climate Change

Nuclear power is a reliable, efficient, stable, and low-carbon emission source of energy. Using nuclear power instead of fossil fuel energy helps mitigate the following negative effects of climate change:

  • Melting of sea ice: Since 1979 arctic sea ice has declined by 30%. Sea ice plays a major role in regulating the earth’s climate by reflecting sunlight into space and providing habitat for animal species. If all of the glaciers on Earth melted, sea levels would rise by approximately 70 feet, effectively flooding out every coastal city on the planet. 
  • Changing precipitation patterns: Extreme weather events (e.g., hurricanes, floods, droughts) are becoming more common and more intense. Storm-affected areas will experience increased precipitation and flooding whereas areas located further from storm tracks will experience decreased precipitation and droughts.
  • Ocean acidification: The ocean absorbs 30% of the CO2 released into the atmosphere, which decreases the pH (increases the acidity) of the ocean. In the past 200 years, the pH of oceans has decreased by 0.1 pH units, which translates to a 30% increase in acidity. Aquatic life unable to adjust to this rapid acidification will die off. A prime example of this is coral bleaching, where coral expel the algae (zooxanthellae) living in their tissues as a result of changes in temperature, light, or nutrients. 

The more we reduce CO2 emissions, the more we slow the rate of temperature rise, sea-level rise, ice melting, and ocean acidification. When these rates are slowed, the earth’s biodiversity does not have to struggle to adapt to temperature and pH changes. People will not be displaced due to the flooding of coastal areas. And icebergs will continue to provide climate regulation. 

To help keep global temperature rise below 1.5C, as outlined in the Paris Agreement, we must shift at least 80% of our electricity generation to low carbon sources. And nuclear power is currently the second-largest source of low-carbon energy. Nuclear has reduced CO2 emissions by more than 60 gigatons over the past 50 years, equating to almost 2 years worth of global energy-related emissions.

Final Thoughts

Nuclear power is an incredibly efficient energy source that uses heat acquired from either fusing or splitting the nuclei of atoms to create electricity. Nuclear fusion produces no CO2 emissions and nuclear fusion produces minimal CO2 emissions. The capacity for nuclear power is great, but few countries currently source any or most of their energy from nuclear power.

Nuclear power benefits the environment by mitigating climate change, creating jobs, promoting energy independence, and protecting air quality. Environmental drawbacks associated with nuclear fission include uranium mining and nuclear waste but can be mitigated with proper handling and disposal methods. Nuclear fusion is still in the research and development phase, and more time is needed to perfect the process in a laboratory setting.

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