Scientists in California fired nearly 200 lasers at a cylinder containing a fuel capsule the size of a peppercorn, taking another step toward fusion energy, which, if mastered, could provide the world with a nearly limitless source of clean power. On a December morning last year, scientists at the Lawrence Livermore National Laboratory in California (LLNL) achieved a world first by producing a nuclear fusion reaction that released more energy than it consumed, a process known as “ignition.”
According to a December report from the LLNL, they have now successfully replicated ignition at least three times this year. This is another significant step toward what could one day be a significant solution to the global climate crisis, which is primarily caused by the use of fossil fuels.
For decades, scientists have attempted to harness fusion energy to replicate the sun’s power on Earth.
Following their historic net energy gain last year, the next critical step was to demonstrate that the process could be replicated.
The ability to replicate, according to Brian Appelbe, a research fellow at Imperial College London’s Centre for Inertial Fusion Studies, demonstrates the “robustness” of the process, demonstrating that it can be achieved even when conditions such as the laser or fuel pellet are varied.
Appelbe told CNN that each experiment provides an opportunity to study the physics of ignition in depth. “This provides valuable information to the scientists in addressing the next challenge to be overcome: how to maximize the energy that can be obtained.”
What is nuclear fusion?
Nuclear fusion, unlike nuclear fission, which is generated by the division of atoms in today’s nuclear plants, leaves no legacy of long-lived radioactive waste. As the climate crisis worsens and the urgency of abandoning planet-warming fossil fuels grows, the prospect of an abundant source of safe, clean energy becomes more appealing.
Nuclear fusion, the reaction that powers the sun and other stars, involves smashing two or more atoms together to form a denser one, releasing enormous amounts of energy in the process.
There are various methods for producing energy from fusion, but at NIF, scientists fire nearly 200 lasers at a pellet of hydrogen fuel inside a diamond capsule the size of a peppercorn, which is itself inside a gold cylinder. The lasers heat up the outside of the cylinder, causing a series of very fast explosions that generate large amounts of energy that are collected as heat.
In December 2022, the energy produced was small—it took about 2 megajoules to power the reaction, which released a total of 3.15 megajoules, enough to boil about 10 kettles of water. However, it was sufficient for a successful ignition and to demonstrate that laser fusion could generate energy.
The scientists have repeated the experiment several times since then. According to the report, on July 30, the NIF laser delivered slightly more than 2 megajoules to the target, resulting in 3.88 megajoules of energy—their highest yield to date. Two subsequent experiments in October produced net gains as well.
“These results demonstrated NIF’s ability to consistently produce fusion energy at multi-megajoule levels,” the report said.
However, there is still a long way to go before nuclear fusion can power electric grids and heating systems on a large enough scale. The emphasis now is on building on previous achievements and determining how to dramatically scale up fusion projects while significantly lowering costs.
At the COP28 climate summit in Dubai, US climate envoy John Kerry unveiled an international engagement plan involving more than 30 countries, intending to increase nuclear fusion to help combat climate change.
“There is potential in fusion to revolutionize our world, to change all of the options that are in front of us, and provide the world with abundant and clean energy without the harmful emissions of traditional energy sources,” Kerry told the climate gathering.