Nuclear Fusion Explained: All You Need to Know

Nuclear Fusion Explained: All You Need to Know

By
Grace Smoot

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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.

What nuclear fusion isNuclear fusion is the generation of energy produced when lighter atoms are combined or fused to create larger and heavier atoms.
How nuclear fusion worksNuclear fusion reactions take place inside fusion reactors in plasma, a hot, charged gas made of positive ions and free-moving electrons. Two isotopes of hydrogen (deuterium and tritium) fuse under immense heat and pressure and release massive amounts of energy in the process.
The global capacity of nuclear fusionIn terms of installed capacity, there are currently more than 60 fusion reactors (10 stellarators and 50 tokamaks) in operation worldwide, but there are currently no operating reactors that provide energy to our power grid. 
The carbon footprint of nuclear fusionNuclear fusion produces little to no greenhouse gas emissions and toxic byproducts, making it one of our most environmentally friendly energy sources.
The environmental benefits of nuclear fusionNuclear fusion has a very low carbon footprint, efficiently produces a lot of energy, uses readily available materials, does not produce long-lived nuclear waste, cannot cause a nuclear accident, cannot be used to produce nuclear weapons, and promotes energy security.
The environmental drawbacks of nuclear fusionNuclear fusion can produce short- to medium-term radioactive waste. 
Nuclear fusion and climate changeNuclear fusion combats climate change by mitigating the temperature rise, sea-level rise, ice melting, and ocean acidification associated with global warming.

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 50 tokamaks in operation worldwide, but there are currently no operating reactors that provide energy to our power grid. 

The world’s largest tokamak, named ITER, is currently being built in France. Weighing 23,000 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 27% to over $6 billion in 2022. But this is still much less than will be required in the future, given that the cost of ITER is over $20 billion alone. Nuclear fusion is a capital-intensive process; therefore, investments will need to increase before the technology can become commercially viable. 

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. One study on tokamak fusion power plants found that they emit less CO2 than photovoltaic solar systems and less than double those from nuclear fission reactors. 

The life-cycle stages of nuclear fusionEach stage’s carbon footprint
Building of nuclear fusionSome CO2 emissions from constructing the nuclear fusion power plant and reactor
Operating of nuclear fusionLittle to no CO2 emissions or waste products
Building back of nuclear fusionSome CO2 emissions from deconstructing the power plant and reactor

In terms of installed capacity, there are currently more than 10 stellarators and 50 tokamaks in operation worldwide, but there are currently no operating reactors that provide energy to our power grid. The focus remains on overcoming the two main challenges to nuclear fusion: keeping the reaction going and generating more energy from the reaction than was required to start the reaction. 

Related: Are you interested in learning more about the carbon footprint of nuclear fusion? Check it out in this article here: “What Is the Carbon Footprint of Nuclear Fusion? A Life-Cycle Assessment”

How Environmentally Friendly Is Nuclear Fusion

Experts tout nuclear fusion as a clean, safe, reliable, and environmentally friendly energy source.

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

Cambridge Dictionary

Nuclear fusion can reduce the effects of global warming by limiting global emissions, and it comes with minimal negative environmental effects.

What Are The Environmental Benefits of Nuclear Fusion

Nuclear fusion has the potential to play a key role in the clean energy movement. This is because nuclear fusion:

  • Has a low carbon footprint: Nuclear fusion produces little to no greenhouse gas emissions and toxic byproducts, making it one of our most environmentally friendly sources of energy. One study on tokamak fusion power plants found that they emit less CO2 than photovoltaic solar systems and less than double those from nuclear fission reactors. 
  • Uses readily available materials: The fusion reaction is most readily feasible between deuterium and tritium, two isotopes of hydrogen. Deuterium is naturally abundant in seawater, and tritium can be bred from lithium, which is naturally abundant in the Earth’s crust and in seawater. Compare this to Uranium-235, the ingredient for nuclear fission, which has a concentration of only 2.8 parts per million (0.7% abundance) in the Earth’s crust.
  • Does not produce long-lived nuclear waste: Unlike nuclear fission, nuclear fusion reactions do not produce long-lived nuclear waste. The only byproducts are helium (an inert gas) and tritium. Although tritium is radioactive, it is produced and consumed within the plant in a closed circuit and is only used in low amounts. 
  • Cannot cause a nuclear accident: Unlike nuclear fission, nuclear fusion reactions are not based on chain reactions. Plasma must be kept at very high temperatures and pressures, with the support of external heating systems and magnetic fields. If there is a loss of pressure or temperature, the reactor shuts down with no adverse effects to the outside world.
  • Cannot be used to produce nuclear weapons: Hydrogen bombs do use fusion reactions; however, they require an additional nuclear fission bomb to detonate. Fusion fuel is also continuously injected and consumed in fusion reactors, so there is never enough fuel lying around to produce a weapon.
  • Promotes energy security: Nuclear energy contributes to energy security by increasing the stability of our power grids. Unlike renewable energy, which faces variations in supply and demand, nuclear energy can provide a reliable and consistent source of clean energy. 

What Are The Environmental Drawbacks of Nuclear Fusion

Nuclear fusion does not generate long-lived radioactive waste; however, experts have noted that nuclear fusion can produce short- to medium-term radioactive waste. Component materials constantly bombarded by neutrons will become radioactive over time and generate nuclear waste. The amount of waste would be comparable to waste generated by nuclear fission, but nuclear fusions’ waste is less radioactive in the long term.

In addition, tritium is weakly radioactive. If tritium were leaked into the environment, it could be difficult to contain given that it can penetrate concrete and rubber. It is also easily incorporated into water and can make water weakly radioactive. Tritium has a half-life of roughly 12 years, meaning it could persist up to 125 years after it is created. 

Although tritium is radioactive, it is produced and consumed within the plant in a closed circuit and is only used in low amounts. Still, the possibility of leaks has spurred research into deuterium-deuterium fusion, because deuterium is not radioactive.

What Are Other Drawbacks of Nuclear Fusion

Because nuclear fusion produces zero CO2 emissions, there are very few environmental drawbacks; however, significant logistical challenges are preventing 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 sustain a nuclear fusion reaction, hydrogen isotopes must be confined at extremely high pressures and temperatures that are several times hotter than the sun.

Hydrogen atoms on the sun can fuse at temperatures of 15 million degrees Celsius, but because Earth has weaker gravitational forces, achieving fusion requires maintaining temperatures upwards of 150 million degrees Celsius. Developing a machine to contain and maintain that amount of heat and pressure has proved difficult thus far. 

In 2021, JET held a nuclear fusion reaction for 5 seconds to produce 59 megajoules (MJ) of energy, almost double that of the previous record. However, scientists had to put 3x as much energy into the system as was created by the reaction.

In December 2022, The National Ignition Facility at Lawrence Livermore National Laboratory in California (US) created a fusion reaction that produced more energy than was needed to spark the reaction. The machine’s laser fired 2 megajoules onto a target and produced 3 megajoules of energy. This demonstrated the viability of nuclear fusion energy for the first time ever.

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:

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 1.5°C, as outlined in the Paris Agreement, we must shift at least 80% of our electricity generation to low-carbon sources. Over 140 countries have stated a net-zero target, covering roughly 88% of the world’s emissions. However, under current conditions, global emissions are projected to increase by 9% by 2030 instead of the 45% reduction in emissions that is needed.

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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