Reaching for the power source of the stars: scientists complete a new milestone towards nuclear fusion
Could harnessing the power of the sun be the answer to humanity’s energy requirements?
Energy consumption worldwide accelerates every year and, with that, fossil-fuel use and its environmental impact also continues to increase. The need for clean, abundant energy sources is more urgent than ever.
For decades scientists have contemplated the seemingly endless flow of energy from the Sun to the Earth and have tried to replicate this power. Recently, scientists at the US National Ignition Facility (NIF) attained a significant milestone that brought us closer to being able to use the power source of the stars to provide the world with safe, clean, renewable, and abundant energy.
Coal power plant.
The Sun and the trillions of other stars in the universe generate energy through nuclear fusion. The term fusion comes from the fact that, during this process, two lighter atomic nuclei merge to form one heavier nucleus. The mass of the resulting nucleus differs from the sum of the two lighter nuclei, and the difference is either released or absorbed as energy in the form of subatomic particles – either chargeless neutrons or positively charged protons.
Nuclear fusion differs significantly from fission, the process used in nuclear power plants worldwide. Fission goes in the opposite direction of fusion, as it consists of splitting a large atom into smaller ones, which does not typically occur in nature. This process generates many highly radioactive particles, while fusion produces little to none. Besides this, because fusion reactions require exceptionally high density and temperature to occur, fusion reactors cannot sustain a chain reaction, meaning that there is no risk of a meltdown.
Scientists working on fusion energy usually focus on the deuterium-tritium (DT) fusion reaction. Deuterium is one of two stable isotopes of hydrogen and contains one proton and one neutron in its nucleus. Tritium is a rare and radioactive isotope of hydrogen, containing one proton and two neutrons in its nucleus. DT fusion produces a neutron and a helium nucleus and releases of a great amount of energy. In addition to that, the elements involved in DT fusion can exist in lower temperatures than other elements.
Deuterium-tritium nuclear fusion.
On August 8th, 2021, scientists at the NIF conducted an experiment to generate energy through nuclear fusion, and for the first time they were able to reach ignition. Focusing a pulse of light on tiny spots within a 10-meter diameter vacuum chamber, they collapsed a capsule of DT, initially smaller than a pea, to the diameter of a human hair. Even though these magnitudes might not seem impressive at first glance, this created the conditions for the atoms to undergo fusion and release 10 million times more energy than the same mass of burning coal would produce.
“Fusion ignition is the point at which a nuclear fusion reaction becomes self-sustaining. This occurs when the energy being given off by the fusion reactions heats the fuel mass more rapidly than various loss mechanisms cool it. At this point, the external energy needed to heat the fuel to fusion temperatures is no longer needed. As the rate of fusion varies with temperature, the point of ignition for any given machine is typically expressed as a temperature.” https://en.wikipedia.org/wiki/Fusion_ignition
The National Ignition Facility (NIF) target chamber.
The amount of energy released in this experiment at NIF was 23 times larger than their own 2018 record and over 1,000 times better than their results in 2011, which shows the incredible advancements obtained by the team in a very short period. They have now been able to output 70% of the energy that was input to achieve the reaction as nuclear energy. This is the closest we ever got to achieving net energy gain – obtaining more than 100% of the energy put in as released energy.
Scientists have not always been optimistic about our chances of actually using nuclear fusion. In 2016, the US Department of Energy even declared that the NIF would possibly never reach ignition. But with the latest results, the outlook seems to have changed. Dr. Jeremy Chittenden, co-director of the Centre for Inertial Fusion Studies at Imperial College London, reported optimistically that “The pace of improvement in energy output has been rapid, suggesting we may soon reach more energy milestones, such as exceeding the energy input from the lasers used to kickstart the process.”
The US Department of Energy is not the only one on the quest for fusion power. In May 2021, China’s Experimental Advanced Superconducting Tokamak (East) set a record by keeping fuel stable for 100 seconds at a temperature eight times hotter than the Sun’s core. The world’s largest magnetic fusion machine is currently under construction in France. The Joint European Torus (Jet), based in the UK, plans to set a new world record for energy output in the upcoming months. And on top of that, we are seeing the emergence of private sector fusion firms.
An internal view of the Joint European Torus vessel.
Fusion startups are being created all over the world and the Fusion Industry Association estimates that they have already attracted over $2 billion of investment. Several experimental reactors are already being constructed or underway. Examples include a reactor by Commonwealth Fusion Systems in Massachusetts and the plant by General Fusion to be constructed in the UK. Specialists speculate that the long-dreamed net energy gain may be just one or two more improvements away.
Beyond the increased demand for energy and the consequent economic interest revolving around fusion power, climate change and biodiversity conservation worldwide also play a significant role in this revolution. As human activities add further stress to the global climate and biodiversity, fusion power could make it easier (or at least possible) for many nations to meet their carbon emission targets.
Nuclear fusion uses fuel that is plentiful enough to last for thousands of years, doesn’t produce carbon dioxide or long-lived radioactive waste, and unlike nuclear fission has zero chance of a meltdown. Additionally, unlike other renewable energy sources, such as wind and solar power, facilities to produce fusion energy would take up little space compared to their energy output. Once we obtain the necessary technology, fusion power could contribute to fighting climate change both by replacing other power sources and by effectively powering the sequestration of carbon dioxide from the atmosphere.