Yesterday, the US Department of Energy announced a huge breakthrough regarding nuclear fusion. For the first time, scientists at the National Ignition Facility (NIF) at the federal Lawrence Livermore National Laboratory in California have successfully achieved a net energy gain, which means that the energy generated by nuclear fusion is greater than the amount of energy employed.
This discovery has the potential to unleash limitless sources of clean energy while eliminating the need for fossil fuels. And it comes as many countries struggle with soaring energy prices and a need to find alternative forms of energy to halt global rising temperature levels.
What is nuclear fusion?
The idea of nuclear power can be traced back to the 1950s when the first nuclear reactor ever constructed generated electricity. As the century progressed, many nuclear power plants began to spring up, with the United States currently being the largest producer.
Yet, the process typically employed inside existing reactors is called nuclear fission. This action consists of the splitting of an atom through the use of a neutron. Each fission results in two lighter nuclei and two or three other neutrons, which collide with other nuclei, forming a nuclear chain reaction. In a controlled environment—a reactor—the result of this chain reaction produces energy in the form of heat and radiation.
Now, nuclear fusion works differently, and it is the type of reaction that happens constantly inside the sun. To produce fusion energy, two hydrogen isotopes are smashed together to form another element, typically helium, with a smaller mass, and a neutron. As a result of this collision, we have energy that can be used just like the one produced by fission.
Why this breakthrough is important
The first fusion reactor was called a tokamak and was initially discovered by Soviet physicists in 1958. Subsequent tokamaks were constructed in the following years around other parts of the world, and scientists still use them up to this day.
But how does it work? It is shaped like a doughnut, with giant magnets on the outside wall. When the fusion happens, the fuel inside the reactor reaches at least 150 million degrees Celsius, and the heat produced gets absorbed by the wall. The heat is used to warm water and produce steam that is then used to power turbines that generate electricity.
Up until a couple of months ago, the energy required for fusion was greater than the one obtained by the process. Then, earlier in February, scientists at the Joint European Torus facility in Oxford, England, produced through nuclear fusion the energy required to boil 60 kettles although only for five seconds.
And now, with the latest breakthrough, scientists at NIF have managed to unleash 2.5 MJ of energy after using just 2.1 MJ, obtaining more energy than they put in. The process happened through so-called thermonuclear inertial fusion, which shoots lasers at hydrogen atoms to create heat—a different technique from the one employed by a tokamak. But whether through nuclear fission or fusion, the result is always the same: clean energy.
Why is nuclear energy considered clean?
Technically, nuclear energy cannot be considered renewable because it still relies on a finite source, hydrogen. But it still falls under the "clean energy" category.
Firstly, one of the hydrogen isotopes used in a reactor can be commonly found in nature, more specifically in seawater. Therefore, it is very unlikely that there is going to be a shortage of fuel. More importantly, though, nuclear energy does not emit greenhouse gases because fossil fuels are not used. This is why nuclear energy is commonly regarded as a possible climate change solution.
In addition, nuclear energy through fusion is much safer than nuclear energy through fission because it does not create radioactive byproducts that need to be stored somewhere or disposed of.
Another potential risk for power plants that regularly use nuclear fission is the potential for a meltdown, such as in the 2011 Fukushima disaster, which was triggered by an earthquake. It is estimated that certain areas near the reactors still have high radioactivity levels.
But with fusion, the possibility of a meltdown is nil. And that is because fusion does not rely on chain reactions like fission does, meaning that once fuel stops being injected, the reactor will stop creating heat immediately. Creating energy through nuclear fusion is relatively easy; what’s hard is creating sustained fusion energy that can be used on a large scale.
Will this be the end of the fossil fuel era?
The latest breakthrough certainly pushed the race to find alternative sources of energy one step forward. But even nuclear fusion has its downsides.
In particular, the constant bombardment of neutrons against the magnetic shield—which is what happens in a tokamak—makes the shield itself radioactive. So technically, a nuclear fusion reactor does not produce radioactive waste, but it would likely cause radiation damage to the structure itself. As a result, many parts of the structure would need periodic replacements, and the radioactive parts would still need to be disposed of somewhere.
In addition, one of the two isotopes used for nuclear fusion, tritium, is not found naturally like deuterium, the other one. The only other way to produce it is inside the nuclear reactor itself; the tokamak can create it thanks to the collision of neutrons and another element, lithium, which is already in high demand for electric vehicles.
Yet, the NIF breakthrough remains a huge discovery that has the potential for clean energy, despite only being a scientific demonstration that is not quite ready for commercial use. In an interview with The Guardian, Jeremy Chittenden, professor of plasma physics at Imperial College London, said: “To turn fusion into a power source, we will need to boost the energy gain still further.” [..]
“We will also need to find a way to reproduce the same effect much more frequently and much more cheaply before we can turn this into a power plant,” he added.
And a future where nuclear fusion becomes commercially viable does not seem too far-fetched. One of the biggest tokamaks, the International Thermonuclear Experimental Reactor, is currently being constructed in southern France and being financed by 35 other nations. It is set to begin operating in late 2025.
Photo credit: ITER
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