Harnessing the Power of Stars: Fusion Energy

28th February 2023 - Last modified 4th July 2024

By Bree Foster PhD, Science Writer

The ideal energy source is constant, sustainable, and doesn’t produce harmful waste. It’s also almost too good to be true. Except that it’s not. Could a potential alternative be the power that lights the universe? Maybe someday, this same power could light our homes too.

Reaching for the Stars

Energy is essential for the functioning of modern-day society. Energy lights our homes, grows our food, transports goods, and makes modern communication possible.

The discovery and use of fossil fuels in the early 19^th century has formed and shaped the world we live in today. Fossil fuels have allowed human health, welfare, and our technological capacity to improve markedly – alongside a massive increase in the human population. However, fossil fuels also release carbon dioxide, a gas that has been shown to significantly alter our climate by raising global temperatures.

While there are alternative energy sources like renewables and nuclear, these options also have drawbacks. For example, renewable energy sources like wind and solar rely heavily on the weather and so need batteries to store excess energy for times when the wind isn’t blowing or the sun isn’t shining. These batteries are still expensive and require rare materials that need to be mined, often causing soil degradation, biodiversity loss and water conflicts in the local area. And the traditional form of nuclear energy, known as nuclear fission, produces a lot of toxic waste and, if not carefully managed, can result in nuclear explosions or fallout where radioactive particles contaminate our atmosphere, soil, and water.

Another potential form of nuclear energy is known as fusion power. This is the energy that powers the stars and the universe. If we could harness that power, there would be a virtually unlimited amount of energy that could propel humanity’s progress to unimaginable heights.  

What’s the Difference Between Fusion and Fission?

Fusion energy powers the stars! By using extremely high temperatures and pressures, lighter hydrogen gases like deuterium and tritium are transformed into heavier ones like helium [1]. This results in the production of more heat that can then cause further reactions, creating a self-sustaining system.

This is different from existing nuclear energy which relies on a process called fission. Fission is the opposite of fusion and results in the splitting of heavy chemical elements to produce lighter ones[2]. While fission energy is extremely reliable, low-carbon, and one of the most efficient forms of energy production, the byproducts of radioactive waste and the possibility of a nuclear meltdown mean that fusion is still considered a safer and more efficient alternative.

The ’Holy Grail’ of Power?

There are incredible advantages to fusion power, making it a very lucrative and exciting possibility, including [3]:

• Plentiful fuel. Fusion fuel is ample and easily accessible. Deuterium can be extracted inexpensively from seawater, and tritium can be produced from naturally abundant lithium. Even with widespread adoption of fusion power stations, these fuel supplies would last for many thousands of years.

• Energy efficient. One kilogram of fusion fuel could provide the same amount of energy as 10 million kilograms of fossil fuel. A 1-Gigawatt fusion power station will need less than one ton of fuel during a year’s operation [3].

• Safe, minimal risk. If something goes wrong with a fusion reactor, there isn’t an explosion, the reaction just stops. Plus, the reaction by-product is helium, which after all, is an element that we use for kids’ party balloons!

• Reliable, self-sustaining power. Fusion power plants will be designed to produce a continuous supply of large amounts of electricity.

• No harmful waste. As mentioned, the only by-product of a fusion reaction is a small amount of helium, which is an inert gas that can be safely released without harming the environment.

What’s the problem?

Unfortunately, there are some issues. Fusion fuel must be heated to extreme temperatures of up to 300 million degrees, and must be kept stable under intense pressure, and dense enough and confined for long enough to allow the nuclei to fuse. Heating the target in this way generates an electrically-charged gas called plasma, which is difficult to contain and compress.  

There are currently two main methods for producing the heat necessary for fusion and containing the resulting plasma[4]:

• Magnetic confinement reactor: This method uses strong magnetic fields to contain the hot plasma and then heat it up using a combination of microwaves, radio waves, and particle beams.

• Inertial confinement reactor: This method involves compressing a small pellet containing fusion fuel to extremely high densities using strong lasers or particle beams.

However, although many fusion reactors have been built, no reactor has ever produced a positive fusion energy gain factor, i.e., more power output than input.

Until now…

Following six decades of toil and failure, the US National Ignition Facility (NIF) has – for the first time – used an inertial confinement laser-driven fusion machine to conclusively produce more energy than was required to initiate the reactor [5].

In the recent NIF experiment, a powerful laser made up of 192 beams was used to input 2.05 megajoules (MJ) of energy into a tiny capsule filled with hydrogen fuel. This compressed the fuel to 100 times the density of lead and heated it to 100 million degrees Celsius – hotter than the centre of the Sun! In the plasma, hydrogen atoms were then forced to fuse together, generating 3.15 MJ of energy in the process. While the numbers might seem small, this represents a significant achievement for the progress of fusion power. This experiment proves that fusion power can be used to generate energy and it’s now up to engineers to increase capacity for commercialisation.     

To a newcomer, 1.1 MJ of net energy may not seem like anything to be excited about but when Wilbur and Orville Wright took flight for the first time, it only lasted 12 seconds and covered 120 feet [6]. 44 years later, we achieved supersonic flight [7].

This is the first step of many to a potentially very exciting future.

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References

(1) İlhami, Y. and MacEachern, C. 2018. 1.2 Historical Aspects of Energy. In: Dincer, I. ed. Comprehensive Energy Systems. Oxford: Elsevier, pp. 24–48. Available at: https://www.sciencedirect.com/science/article/pii/B9780128095973001024 [Accessed: 7 February 2023].

(2) Şahin, S. and Wu, Y. 2018. 3.14 Fission Energy Production. In: Dincer, I. ed. Comprehensive Energy Systems. Oxford: Elsevier, pp. 590–637. Available at: https://www.sciencedirect.com/science/article/pii/B978012809597300331X [Accessed: 7 February 2023].

(3) Fusion in brief. Available at: https://ccfe.ukaea.uk/fusion-energy/fusion-in-brief/ [Accessed: 7 February 2023].

(4) Nuclear Fusion Basics. 2010. Available at: https://www.iaea.org/newscenter/news/nuclear-fusion-basics [Accessed: 7 February 2023].

(5) BBC News 2022. Breakthrough in nuclear fusion energy announced. 13 December. Available at: https://www.bbc.com/news/science-environment-63950962 [Accessed: 7 February 2023].

(6) 1903 Wright Flyer | National Air and Space Museum. [no date]. Available at: https://airandspace.si.edu/collection-objects/1903-wright-flyer/nasm_A19610048000 [Accessed: 7 February 2023].

(7) Supersonic flight | Britannica. Available at: https://www.britannica.com/technology/supersonic-flight [Accessed: 7 February 2023].