13 December 2022 |



You may have seen the headlines. Or the breathless Tweets. Researchers at the National Ignition Facility (‘NIF’) at the Lawrence Livermore National Laboratory achieved a “breakthrough” in nuclear fusion. They did so using the world’s largest laser to bombard a perfectly spherical pellet of hydrogen plasma.

First, it helps to appreciate that fusion advances are more ‘parade’ than single event. The same lab achieved a smaller 1.3 megajoules of ‘yield’ in August last year, a notable accomplishment at the time. That represented a yield of ~70% in terms of energy output vs. input into the system.

Today, the NIF unfurled a new banner in the parade. And it’s a big banner, to be sure. Namely, what’s dubbed fusion ignition, i.e., successfully creating a self-sustaining burning plasma. They fired 2.05 megajoules (MJ) of energy into a target via laser and reaped 3.15 MJ of fusion energy output. So instead of getting 70% of the input back out, they achieved a ~150% overall yield.

Is this an important milestone? Yes, ignition is in the National ‘Ignition’ Facility’s name, after all. But is it earth-shattering? Read on.

A rendering by Khyati Trehan depicting how DeepMind’s AI can help fusion via ‘learned plasma control.

Back to the basics 

If you’re feeling confused about fusion, fuels, lasers, targets, yield, energy gain, and more, don’t fret. Let’s break down the basics a bit. 

In general, nuclear fusion seeks to replicate the Sun’s power. When particles fuse, they release energy. In the core of the Sun, nuclear fusion reactions are ongoing, with hydrogen atoms fusing into helium atoms, releasing energy.

Next up, if you get nothing else out of today’s newsletter, let it be this. Several unique approaches aim to create and control fusion reactions on Earth. When people say ‘fusion,’ beyond fusing particles, they don’t always mean the same thing. This complicates comparisons between labs, companies, and paths to commercialization.

Two main approaches to sustain and control fusion reactions on Earth are magnetic confinement and inertial confinement fusion (as an aside, we know how to create uncontrolled fusion reactions; that’s part of how second-generation nuclear bombs work.) 

Magnetic confinement uses magnets to create and confine a continuous plasma in which fusion can occur. Inertial confinement, which the NIF works on, means that the target plasma (the perfectly spherical hydrogen pellet) is held within a containment capsule and bombarded with lasers or other devices to try and generate energy. The laser can only fire ever so often, making this process discrete vs. continuous.

Many power plants generate electricity via the same mechanism, whether fired by coal, gas, fission, or, someday, fusion. They produce heat.

If inertial confinement fusion translates into power plants in the future, it may well produce electricity similarly. That said, most private fusion companies work on magnetic fusion, which is likely closer to viability for electricity generation.

Suppose you were trying to commercialize a new energy source and had to pick between a continuous (magnetic) vs. discrete (inertial confinement) process, all other things equal. You’d probably go with the continuous option. Said differently, today’s news doesn’t directly impact the tech closest to commercializing fusion for electricity generation and grid connection.

Briefly, here’s a (very rough) sketch of a magnetic confinement approach, which would offer a non-heat-based path to generating electricity:

  1. Heat fuel to high temperatures, creating plasma conditions, i.e., the fourth state of matter beyond gas, liquid, and solid.
  2. If you’re wondering how the plasma doesn’t burn its way to the Earth’s core, the fusion reactor ‘confines’ the plasma in a magnetic field.
  3. The magnetic field also helps compress the plasma to increase the temperature (up to 100M° C) so particles move quickly enough to fuse.
  4. Fusion releases energy, expanding the plasma. As the plasma expands, it ‘pushes’ back on the magnetic field.
  5. Changes in the magnetic field can create current / electricity.

Again, to reiterate, that’s very different from what the NIF did to achieve ignition. There are similar fundamentals in underlying physics and technical components, such as the type of diagnostic equipment you might leverage to study results. But on the whole, ‘fusion’ as a catch-all category feels limiting. 

Private firms working on magnetic confinement also don’t typically disclose nearly as much about where they’re at progress-wise. I spoke to one representative of a firm today for their reaction and they noted it’s ‘definitely possible’ others firms have achieved net energy gain and just didn’t say anything yet.


Back to the NIF. Accolades and optimism are warranted. Ignition is a significant milestone folks have been striving to achieve and referencing as a bellwether for a long time. The tech at the NIF is also based on, in their own words, “1980s lasers” (per today’s press conference). So, if this proof of concept leads to more funding for more advanced equipment (as I’m sure NIF and LLNL hope), perhaps further breakthroughs will follow soon. 

But it’d be misguided to characterize this milestone as the big unlock that will beckon in an era of limitless energy for all. For one, it was one ignition, one time. Again, not making light of that. But for sustained energy, you’d need to achieve that many times per minute. 

The net energy gain is also only at the level of the target. Powering up the laser itself required 300 MJ ‘from the wall,’ as it were. The result was a ~2 MJ laser shot that produced ~3 MJ of energy. There was still a significant net loss of energy at the system level. 

At the press conference, Dr. Kim Budil, the director of the LLNL, noted that this tech is still far off from commercial viability. In her words: 

Not six decades, not five decades… It’s moving into the foreground… a few decades of research could put us in position to build a power plant.

For more on the technical challenges ahead for inertial confinement fusion before it can generate electricity, you can also explore here.

We’ve been here before

Taking a step back, this isn’t the first time we’ve gotten excited as a species about a potential ‘silver bullet’ for energy. Around the 1950s, humanity began connecting new, highly efficient power plants to the grid that used an extremely energy-dense fuel source. The amount of electricity from this type of power generation skyrocketed for decades until high-profile accidents (terrible ones, to be sure) derailed progress, and regulations in many places became too onerous for developers to navigate. New deployment stagnated. 

Sound familiar? It’s nuclear fission. Here’s a chart of global nuclear power generation since 1960. Up, up!… and then all of a sudden, pretty flat:

Whether fusing or splitting atoms, there is massive energy potential at hand. Fission reactions are more straightforward to achieve than fusion ones. We know how to start and control fission reactions and have for the better part of a century. Meanwhile, as discussed, fusion reactions are proving much more challenging to start, let alone sustain. 

I also offer this reminder about nuclear fission to suggest that the tech for energy generation itself is only one of many factors relevant to whether people use it. Fission is effective and versatile, but most countries aren’t developing new plants or are even shutting down existing ones that work fine. Other factors are at play here, including:

  • Public sector support
  • Regulation and the requisite infrastructure
  • Economics
  • Public sentiment 

While public sector support and public sentiment hold back fission, beyond the tech itself, fusion will be held back by economics for some time. What ultimately matters isn’t net energy but net electricity. More specifically, what will a kilowatt-hour from fusion cost? Despite all the hubbub over the past few days, we’re still a ways away from finding out. Prospective fusion developers must replicate their success in ideal settings countless times. And then do it on ever-increasing and more efficient scales. And then begin navigating the restrictions and processes to move into ‘real’ applications. 

I’m rooting for ’em! In the interim, countries investing in next-generation nuclear are perhaps best-positioned to dramatically decarbonize their grids.

The net-net

Hopefully, I don’t sound like too much of a curmudgeon to you right now. Scientific breakthroughs and improvements are always welcome here. Ignition in fusion is incredible. I’m a big tent guy; I’d love to see a pie chart for the world’s energy mix circa 2050 that includes nuclear fission, fusion, hydropower, solar, wind, tidal and wave energy, and, realistically, lingering natural gas capacity. 

It’s also worth shouting out the importance of public sector investment in fusion research. It’s a relatively recent development that the private sector has taken an interest in fusion. And I’m excited about the growing “portfolio approach” to fusion, where many players are testing different concepts and approaches. The technologies developed to make fusion work will also find use elsewhere. 

But it’s also important not to overhype any advancement—the first cleantech movement this century ended in an ugly bust. Managing expectations is essential to ensure that doesn’t happen again.

For fusion, coverage of breakthroughs must pair with balanced assessments of the roadmap from the lab to grid-connected electricity source. Otherwise, the average joe reading the paper will start to sour when the umpteenth fusion breakthrough still doesn’t translate into a lower electricity bill. 

To state it clearly, fusion, whether from magnetic or inertial confinement, is no white knight. Nor is there any such single ‘savior’ for the energy transition. A mosaic of many solutions & mindset shifts is required.