Nuclear fusion involves combining lighter atoms to produce heavier atoms, a process that generates energy. It has yet to become a mainstream energy source due to various technological barriers but could provide enormous amounts of clean energy if harnessed fully. So, we had to ask: What is nuclear fusion really, and how can it help mitigate climate change?

Nuclear fusion is the generation of energy produced when combining lighter atoms to form heavier ones. Nuclear fusion produces little to no greenhouse gas emissions or toxic byproducts, but it is still being researched and does not yet supply energy to our power grid.

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

The Big Picture of Nuclear Fusion

Nuclear fusion contributes to the avoidance of greenhouse gas (GHG) emissions from the burning of fossil fuels (e.g., coal, oil, natural gas). The supply of fuel for nuclear fusion is virtually unlimited, but it is still classified as a nonrenewable energy source.

How Is Nuclear Fusion Defined

Nuclear fusion, one of two ways to produce nuclear energy, is the generation of energy produced when lighter atoms are combined or fused to create larger and heavier atoms.

“Nuclear fusion: the process of joining two nuclei to produce energy.”

Cambridge Dictionary

Nuclear fusion is still very much in the research and development phase. The fusion process is very hard to control within a laboratory setting. More research and development still needs to be done to determine if fusion could be another viable energy source.

How Does Nuclear Fusion Work

Nuclear fusion is the process by which lighter atoms are combined or fused to create larger and heavier atoms. Fusion reactions take place inside fusion reactors in plasma, a hot, charged gas made of positive ions and free-moving electrons. 

The two most common fusion reactors in use today are tokamaks and stellarators. Both use magnetic fields to confine plasma in the shape of a donut.

• Tokamaks: Induce electric currents inside of the plasma. Tokamaks are easier to build than stellarators and are better at keeping plasmas hot. They are the preferred option today for nuclear fusion energy power plants.

• Stellarators: Use external coils to generate a twisting magnetic field. They require less injected power, have greater design flexibility, and are better at keeping plasma stable than tokamaks. However, they are also more complex to build. 

How Does Nuclear Fusion Actually Produce Energy

Nuclear fusion power plants generally operate in the following manner:

• Deuterium (D) and Tritium (T) are introduced into a fusion reactor and heated upwards of 150 million degrees Celsius
• The deuterium and tritium fuse together, forming an electrically charged gas known as plasma and releasing massive amounts of energy and neutrons
• A lithium blanket surrounding the core of the fusion reactor absorbs the kinetic energy of the neutrons, causing the blanket to heat up
• As the blanket heats up, the lithium is transformed into tritium (which is used to fuel the reaction) and helium
• The energy, in the form of heat, is collected by the coolant (water, helium, or Li-Pb eutectic) flowing through the blanket
• The heat can be used to generate electricity 

What Is the Global Capacity of Nuclear Fusion

In terms of installed capacity, there are currently more than 10 stellarators and 60 tokamaks in operation worldwide, but there are currently no operating reactors that provide energy to our power grid. 

As part of The International Thermonuclear Experimental Reactor (ITER) agreement, the world’s largest tokamak, also named ITER, is currently being built in France. Weighing 23,00 tons, the machine will be able to maintain a temperature 10x that of the sun’s core and will have a 500 MW fusion energy output power once constructed. Although it will not be used to generate electricity, the technology of ITER will set the standard for future reactors.

In terms of funding, nuclear fusion investments grew to over $7.1 billion in 2024. Most notably, the amount of public investment into private companies grew from $271 million in 2023 to $426 million in 2024, indicating a heightened interest in commercializing nuclear fusion sooner rather than later.

What Is the Carbon Footprint of Nuclear Fusion

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

“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 or driving a car) and GHG emissions from manufacturing the products that we use (e.g., power plants, factories, and landfills). 

Nuclear fusion produces little to no greenhouse gas emissions and toxic byproducts, making it one of our most environmentally friendly energy sources. 

On a per-mass basis, nuclear fusion can generate four times as much energy as nuclear fission while producing very little carbon dioxide (CO₂) or radioactive byproducts. One study on tokamak fusion power plants found that they emit less CO₂ than photovoltaic solar systems and less than half those from nuclear fission reactors. 

How Environmentally Friendly Is Nuclear Fusion

Overall, nuclear fusion is considered to be environmentally friendly.

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

Cambridge Dictionary

Nuclear fusion produces minimal emissions, cannot cause a nuclear disaster, and does not produce long-lived nuclear wastes.

What Are The Environmental Benefits of Nuclear Fusion

Nuclear fusion has a low carbon footprint, cannot cause a nuclear accident, produces very few waste products, and protects air quality.

What Are The Environmental Drawbacks of Nuclear Fusion

Nuclear fusion generates low and intermediate levels of nuclear waste. In addition, the unresolved engineering challenges may prevent us from commercializing fusion before it is too late to save our climate. 

What Are Other Challenges of Nuclear Fusion

Nuclear fusion has very few environmental drawbacks; however, significant logistical challenges currently prevent nuclear fusion from becoming a mainstream energy source.

Presently, the two main challenges to nuclear fusion are maintaining the reaction and generating more energy from the reaction than was required to start the reaction.

Nuclear fusion experiments themselves are relatively easy to achieve; however, the reaction typically only lasts a fraction of a second. The main challenge with nuclear fusion comes with sustaining fusion reactions for prolonged periods of time. To keep a nuclear fusion reaction going, hydrogen isotopes must be confined and maintained at extremely high pressures and temperatures that are several times hotter than the sun. In addition, scientists have struggled to generate more energy from the reaction than is required to initiate the reaction. 

In terms of recent breakthroughs:

• In 2023, The National Ignition Facility at Lawrence Livermore National Laboratory built upon their 2022 breakthrough by replicating the ignition process three more times, creating more energy from the reaction than was used to initiate the reaction. 
  
• In 2025, The EAST tokamak, a fusion research device located in China, set a new record by maintaining a steady fusion reaction for 1,066 seconds (17.7 minutes).

Why Is Nuclear Fusion Important to Fight Climate Change

Climate change is arguably the most severe, long-term, global impact of fossil fuel combustion. Every year, approximately 33 billion tons (bt) of CO₂ are emitted from burning fossil fuels. The carbon found in fossil fuels reacts with oxygen in the air to produce CO₂. This warms the earth by acting as a heating blanket, and a warmer earth comes with a host of negative side effects. 

Using nuclear fusion instead of fossil fuel energy helps mitigate the following negative effects of climate change:

• Increasing temperatures: Earth’s atmosphere has warmed 1.5°C since 1880. This may not seem like a lot, but these degrees create regional and seasonal temperature extremes, reduce sea ice, intensify rainfall and drought severity, and change habitat ranges for plants and animals.

• Rising sea levels: Global sea levels have increased approximately 8-9 inches since 1880, displacing people living along coastlines and destroying coastal habitats. Roads, bridges, subways, water supplies, oil and gas wells, power plants, sewage treatment plants, and landfills remain at risk if sea level rise goes unchecked. 

• 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 expels 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. Over 120 countries have already stated their net-zero carbon emissions ambitions for 2050 or 2060. But only 12 countries have thus far proposed or enacted any legislation, indicating that there is more work to be done.

Final Thoughts

Nuclear fusion, one of two ways to produce nuclear energy, is the generation of energy produced when combining lighter atoms to form heavier ones. Although there are operational nuclear fusion power plants, none of them currently supply power to our power grid. The fusion process is difficult to replicate in a laboratory setting; therefore, the focus remains on research and development.

Despite numerous benefits, nuclear fusion faces an uncertain future. Although it can produce relatively emissions-free energy and adjust its energy output to compensate for shifts in renewable energy output, it also faces high upfront costs and technological challenges. For nuclear fusion to become a reliable source of energy, more funding and research is needed. 

Stay impactful,

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