All current nuclear power plants in operation around the world use some variant of nuclear fission. In it, a controlled version of a nuclear fission reaction—the very same one inside nuclear armaments—proceeds, with restrictions placed upon it so it doesn’t “run away” and become uncontrollable. The controlled chain reaction releases by-products: fission products, free neutrons, gamma radiation, and kinetic energy. In doing so, the free neutrons may trigger the fission products to proceed the reaction further, continuing the chain. This entire process generates a lot of heat; this heat is then taken away by a cooling system, usually water or some liquid metal, which is then taken away and used to make steam; this then feeds the turbines that generate electricity for the power grid it’s connected to. The process allows the generation of huge amounts of energy to be distributed to homes and commercial spaces; of course, the process generates radioactive waste products as well, whose improper disposal and/or storage can cause devastating consequences for the surrounding neighborhoods and environment. It is thus important for scientists to seek alternatives to nuclear fission, and experts think we might want to look in the other direction: instead of breaking atoms apart, we must bring them together: nuclear fusion.
Nuclear fusion, as the name suggests, necessitates bringing simple atoms together—usually a variant of hydrogen, also known as its isotopes—in order to initiate a self-sustained exothermic reaction. It promises a cleaner, more powerful method of energy generation. And we know it’s extremely efficient at producing power—It’s the very same process that powers the sun. (Read more on how stars generate power here.) However, it has been a struggle for scientists to achieve nuclear fusion. For starters, current experiments at attaining fusion are still putting in more energy into the system compared to the energy that it releases afterwards; the system is consuming energy, not producing it. Replicating the conditions for nuclear fusion inside the stellar core of the Sun here on Earth has also been a herculean task; scientists get around this by taking advantage of the electromagnetic properties of the plasma they create, which is a hot cloud of ions with free electrons around them produced from heating the hydrogen isotopes just above their ionization energy.
The challenge for scientists and engineers, then, is to heat the fuel to the point of nuclear fusion ignition, or the point beyond which the nuclear fusion reaction produces 100% or more of the energy that was used to jump-start it, making the reaction self-sustained and fulfilling the promise of unlimited, clean energy. Problem is, this requires injecting huge amounts of energy into hydrogen pellets; luckily for humanity, researchers over at Lawrence Livermore National Laboratory’s (LLNL) National Ignition Facility (NIF) have brought themselves up to the task. And their most recent results show that they might just be 70% of the way there.
Details from a press release from the Lawrence Livermore National Laboratory show that the team used an array of 192 lasers, combining their beams to inject around 1.9 MJ (megajoules) of energy onto a small chamber containing a hydrogen pellet that’s just about the size of a BB projectile. This vast amount of energy is “pulsed,” with each pulse lasting just a billionth of a second. The resulting pulse of energy enabled the hydrogen in the pellet to release energy in the range of 1.3 MJ—around 70% of the energy injected into it.
“This result is a historic step forward for inertial confinement fusion research, opening a fundamentally new regime for exploration and the advancement of our critical national security missions,” according to LLNL director Kim Budil. “For me it demonstrates one of the most important roles of the national labs – our relentless commitment to tackling the biggest and most important scientific grand challenges and finding solutions where others might be dissuaded by the obstacles.”
According to the team, several improvements can be made to the system to allow for better efficiency in the future; these include modifications to the pellet design that holds the hydrogen isotopes and better laser precision, among others. The team at NIF is currently in preparation for further experiments in the coming months.
These promising results don’t directly translate to applications for nuclear fusion-powered generation plants, however; for starters, the lasers used in NIF can only shoot out large amounts of power for their experiments about once a day; a commercial application, if possible, demands that they fire up these hydrogen pellets multiple times a second. Hope is not lost though, as multiple research teams are currently at work devising new methods to allow for commercialization of these nuclear fusion pathways, making them viable for use.
“This is very promising for us, to achieve an energy source on the planet that won’t emit [carbon dioxide],” said plasma physicist Siegfried Glenzer of the SLAC National Accelerator Laboratory in Stanford University. (Glenzer previously worked at LLNL, and is not involved with the new research there.) He also remains hopeful that further research into this promising field will light the way for humanity to finally break free from fossil fuel consumption, leading the way towards a sustainable future.
Bibliography
- Bishop, B. (2021, August 18). National Ignition Facility experiment puts researchers at threshold of fusion ignition. L:awrence Livermore National Laboratory. Retrieved September 7, 2021, from https://www.llnl.gov/news/national-ignition-facility-experiment-puts-researchers-threshold-fusion-ignition
- Lavars, N. (2021, August 17). High-powered laser closes in on nuclear fusion ignition. New Atlas. Retrieved September 7, 2021, from https://newatlas.com/energy/laser-experiments-nuclear-fusion-ignition-llnl/
- Metcalfe, T. (2021, August 17). Fusion experiment breaks record, blasts out 10 quadrillion watts of power. LiveScience. Retrieved September 7, 2021, from https://www.livescience.com/fusion-experiment-record-breaking-energy.html
