There are many forms of renewable energy in the world today, including solar, wind, and hydropower. But for many scientists, the ultimate Holy Grail of renewable energy is nuclear fusion. For decades, scientists have pursued the elusive dream of this cheap, clean, virtually unlimited power source with little success.
But in recent years, the pieces of the fusion puzzle have started coming together. And in December of 2022, scientists at Lawrence Livermore National Laboratory (LLNL) achieved one of the biggest breakthroughs yet.
To understand the significance of this discovery, you need to understand what nuclear energy means. The nucleus is the mass of protons and neutrons at the center of an atom. Powerful forces hold the nucleus together, and splitting or fusing two nuclei unleashes these forces. These two processes are called fission and fusion.
Existing nuclear power plants rely on fission. They work by splitting atoms of uranium to release energy. As each atom breaks apart, it releases electrons that collide with and split other atoms in a chain reaction.
Nuclear fission has many advantages. A nuclear plant can generate a lot of power from just a little fuel. It has very low greenhouse gas emissions. It doesn’t take up a lot of space. And it can produce steady, reliable power.
But nuclear fission has major drawbacks as well. It’s not renewable because it requires uranium, a limited resource. Uranium mining poses threats to human health and to the environment. The fission process itself produces radioactive waste that can threaten human health without careful containment. And there’s always at least a tiny risk of a major disaster, like Chernobyl in 1986 or Fukushima in 2011.
Nuclear fusion is just the opposite of fission. Instead of breaking atoms apart, fusion smashes two hydrogen atoms together. This creates a single atom of helium—and releases a lot of energy. Like fission, fusion creates free electrons that can trigger a chain reaction. In fact, this is exactly what’s happening right now inside our sun and other stars.
Fusion power offers all the advantages of fission without most of the drawbacks. It’s much more efficient, producing more energy with less fuel. Moreover, that fuel is hydrogen, which is easy to extract from seawater. And it produces much less waste. There’s just one problem: How do you create a sustained fusion reaction without a star?
Scientists have succeeded in fusing atoms before. However, the amount of energy needed to start the reaction was more than it produced before fizzling out. That, obviously, made fusion useless as an energy source.
That changed on December 5, 2022, in the National Ignition Facility (NIF) at LLNL. There, for the first time, scientists achieved a fusion reaction that produced more energy than it took to start.
At the heart of LLNL’s fusion lab sits a cylinder about the size of a pencil eraser. Within this cylinder, scientists placed an even tinier capsule of pure diamond containing two isotopes, or forms, of hydrogen. The facility’s 192 laser beams all focused and fired on this target. This heated it to about 5.4 million degrees F, vaporizing it and releasing a huge burst of X-rays. These, in turn, created enough heat and pressure to crush and fuse the hydrogen atoms into helium.
It took over 10 years and billions of dollars to achieve this feat. For years, the hydrogen failed to “ignite,” or set off a fusion reaction. The NIF team first achieved ignition in August 2021, but the reaction produced less energy than they put in.
After another 16 months of careful adjustments, they finally managed to set off an energy-producing reaction. Using 2.05 megajoules (mJ) of laser energy, they triggered a reaction that released 3.15 mJ. That’s not much energy—less than one kilowatt-hour (kWh). But it proved this technology can work.
That doesn’t mean fusion energy is now a reality, though. While the lasers emitted only 2 mJ, it took 300 mJ of electricity to power them. So although the reaction technically produced energy, it was still only a tiny fraction of the total energy used.
No, it’s not. Most fusion research so far has focused on trying to construct reactors called tokamaks, or “artificial suns.” These contain toroidal (doughnut-shaped) vacuum chambers within which hydrogen gas can be heated to millions of degrees. At this temperature, hydrogen turns from gas to plasma. The electrons in the hydrogen atoms separate from the nuclei, and the nuclei fuse together, releasing energy. A powerful magnetic field within the torus keeps the superheated plasma contained.
Tokamak research has also made major advances in recent years. In 2021, scientists at MIT succeeded in creating a 20-tesla magnetic field, strong enough to contain a fusion reaction. Those scientists are now at work building a test reactor called SPARC. A British company, Tokamak Energy, made a similar breakthrough in superconducting magnet technology that same year.
Another tokamak project, ITER, is under construction in southern France. Scientists from 35 countries are collaborating on it and hope to fire it up in 2025. And in December 2021, China’s Experimental Advanced Superconducting Tokamak (EAST) set a record for the longest sustained fusion reaction—over 17 minutes.
There’s a longstanding joke among scientists about nuclear fusion. They call it the perfect energy source that’s just 30 years away...and always will be.
Recent discoveries in fusion energy have made the second half of this line untrue. The breakthrough at LLNL proves that fusion energy is in fact achievable. One day, this cheap, clean, reliable energy source could provide all the power society needs. Fusion plants could be built anywhere. They wouldn’t take up a lot of space or require a lot of fuel. And they could run 24/7, without depending on weather conditions.
However, the first half of the joke—the 30-year timeline—still holds true. Even after this breakthrough, scientists believe it will be around 30 years before fusion can become a significant energy source. Fusion could be a game changer in the long run. But unless there’s an even bigger breakthrough in the near future, it’s unlikely to speed the transition to net-zero emissions. That’s a goal we need to achieve by 2050 to have a hope of keeping global warming below 1.5°C (2.7°F).
So, the bad news is, fusion isn’t the solution to all our climate woes. Of course, there’s always the possibility of another breakthrough. This success will generate more interest in fusion research, increasing the chances that will happen. But it’s not something we can count on.
The good news is, we don’t need to. We can get to net zero with the energy sources we have already, like wind, solar, and old-school nuclear. And we shouldn’t let the lure of a fusion-based future distract us from the need to grow these existing technologies.
In the long term, innovations like this fusion discovery can push our society forward toward ever cheaper and cleaner energy. But we don’t need to rely on them to achieve a 100% renewable energy future. The solutions we need are available right here, right now.