The Problem With Lasers And Nuclear Fusion

We recently covered a bunch of novel approaches to bring nuclear fusion to the market sooner than you may think. One form of fusion research we didn’t touch on in depth was Inertial confinement fusion (ICF) using lasers… and shortly after publishing that video some major news broke about net positive energy gain using lasers for fusion ignition. As exciting as that news is, there was some nuance to the announcement that got lost in the media hype machine, but it does raise questions about how lasers and fusion work. And what other companies are doing in that area to try and make it a viable path toward fusion energy. Let’s take a closer look at why that fusion announcement is exciting (with some major caveats) and why laser-based fusion may, or may not be, the future of energy generation.

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We’ve walked through the “why” fusion energy is important to the future in previous videos, so I won’t rehash all of that here. I’ll include links in the description in case you want to dive in deeper on that, but at a very high level Fusion has the theoretical potential to be cheap, safe, green, and energy-dense. It’s everything we could realistically want from an energy source, so why isn’t it everywhere?

Generally speaking, it takes more energy to start and maintain a fusion reaction than that reaction outputs … until now. And “now” in this case means December 5th, 2022. That’s when the US National Ignition Facility (or NIF) not only successfully achieved human-made fusion ignition for the first time ever,¹ but had also generated 3.15 megajoules of energy at the cost of only 2.05 megajoules … with an asterisk. Well, a big asterisk, but more on that later. For now that’s roughly 54% extra energy, even a tiny amount of net positive energy generation would be cause to celebrate. But 54%?! With numbers like that it’s easy to see why some of the coverage of the NIF reactor has been so breathless that it missed a few key details. Details that the NIF team pointed out, but didn’t get covered in the same way as the click worthy headline. First, how did NIF do it?

Well, NIF developed an interesting type of fusion reactor based on Inertial Confinement Fusion (ICF). This futuristic process involves placing a one-millimeter hydrogen (deuterium and tritium) isotope capsule inside a hohlraum – a gold, pencil-eraser-sized x-ray “furnace.”² Then they fire 192 high-powered, ultraviolet lasers at the furnace, ² causing it to rapidly implode, shrinking to just 50 microns in diameter. This sudden change in density and temperature generates a fusion reaction in just fractions of a second.² NIF’s ICF reactor is also the first time we have a system in which fusion itself provides most of the heat.² Until now, fusion experiments produced reactions thanks to huge amounts of external heat to warm the plasma, which of course is difficult to produce and costly to maintain. But with the ICF method the reaction happens in an instant, so there’s no need to sustain super-heated temperatures for long periods of time … and again promising increased energy efficiency. And of course, NIF’s reactor has the same benefits of most other fusion reactors – safe, plentiful fuel, no chance of meltdown, and theoretically capable of producing massive amounts of power with no carbon emissions.

While the net positive energy gain is a major scientific milestone, proving that ICF fusion and net energy gain is possible, there are some caveats. Unfortunately, the rush to report on the breakthrough glazed over many of those. While it’s true that lasers delivered 2.05 MJ of heat onto the capsule, which then created 3.15 MJ of fusion generate heat, it took 200 MJs to power those 192 to lasers – just let that sink in for a second. It took 100x more to power the lasers than the lasers could deliver onto the capsule. So, technically it’s a net positive energy gain (the amount of energy delivered to the surface of the capsule vs. what was produced in the chamber), but that’s not accounting for the incredibly inefficient lasers that were used in the experiment. There’s nothing underhanded going on here, NIF officials have been upfront about this wrinkle even during the press conference, but it wasn’t called out in most of the reporting.³

There are also some problems with the fuel pellets themselves. The most successful pellets were made from diamond, and machined to be as smooth as possible⁴ – neither of which could have been cheap. Then there’s the fuel itself – while hydrogen is everywhere and even deuterium doesn’t pose much of a problem, tritium is one of the rarest and most expensive materials on the planet. There’s no easy way to synthesize it, and at current projections a ICF power plant would run through millions of dollars of it every day – talk about cost and supply chain issues. And speaking of a hypothetical ICF power plant, to generate enough energy for a power grid you’d want multiple fusion reactions a day, which means lasers firing many, many times per day. But as it stands, the NIF facility can only fire ONCE a day before the parts need to be cleaned, replaced, and the chamber cooled to just a few degrees above absolute zero.⁵ From a scientific point of view, this is a tremendous step forward and deserves to be celebrated. But commercially? The path to fusion-powered cities is long and winding, and this isn’t the winning design. Does this mean for ICF and using lasers for fusion are dead ends? Or is there a path forward here?

ICF Fusion Competitors

NIF isn’t the only group experimenting with ICF or laser technology. We’ve talked about First Light Fusion in previous videos, but at a high level their approach to ICF is much more ballistic than their colleagues. They were inspired by the pistol-shrimp, y’know the little crustacean that can snap its claws shut so fast that it creates low-pressure zone bubbles which collapse to form 4700 °C plasma bursts?⁶ First Light are replicating this process in their reactor by using a type of railgun to fire a metal disk-shaped projectile at a cube filled with a fuel source in a central cavity. The projectile’s impact creates shock waves, which produce bubbles in the fuel, and as they collapse, the fuel inside is compressed enough to fuse. Same result as NIF, but different method. They’re avoiding the use of inefficient lasers. They also differ from their peers when it comes to energy collection. FLF uses a lithium-based coolant inside their fusion chamber, which helps to protect the chamber from the huge amount of energy that’s released, as well as helping to transfer the heat to a heat exchanger. From there the heat is transferred into water to generate steam that turns a turbine for electricity production. In the end mechanically it’s not too dissimilar from traditional power plants.^{6 7}

Then there’s HB11 out of Australia. Their physical reactor itself is mostly an empty metal sphere with a “modestly sized” boron fuel pellet (around 1 mm in size) in the center and two (yes, just two) high-powered, high-precision lasers on either side.^{8 9} The first laser, in combination with a capacitive coil, establishes a kilotesla magnetic field for the plasma. Reminiscent of First Light’s railgun, the second laser fires a hydrogen isotope into the boron 11 fuel pellet, which both fuses and splits into 3 alpha particles per reaction (notation: p+B→ 3*alpha + 8.7 MeV).⁸ To take something complicated and boil it down to where my brain can understand it … bang, instant fusion.

This take on fusion has a number of advantages. First, hydrogen is the most abundant element in the universe, while boron-11 is also very common (it makes up about 80% of all boron found in nature).¹⁰ And in case you were worried neither isotope is radioactive, as opposed to some other fusion techniques where a little radioactive material is sometimes required to kick start the reaction. Like other ICF reactors, the laser-fired hydrogen also means you don’t need to heat things up to 10-times-the-core-of-the-sun temperatures or keep the chamber under as intense pressure with magnets¹¹ – both of which cost a lot of energy.¹²

Because of the relatively small size of their reactor, HB11’s fusion reactor doesn’t require large plants or big footprint, which means it could potentially work for grid integration or more remote power generation. And speaking of the grid, because this form of fusion releases energy as charged particles, there’s no need to go through the process of transferring the heat to make steam and turn a turbine. The reactor sphere just collects the charged particles and can send that electricity directly to the grid.¹³ It has a bit of an overlap with Helion’s fusion approach that I talked about in the last fusion video. But perhaps most exciting of all, HB11’s newest laser fusion method also generated 10 times more fusion energy than expected.¹⁴ Still not enough net energy to contest NIF’s breakthrough, but definitely an encouraging result.

Challenges & Reasons to be Optimistic

Is laser fusion or ICF the last piece of the puzzle? Is this it, can we finally shelve the “no matter what, fusion is always just 30 years away” jokes? Well, yes and no, but mostly no. Don’t get it twisted, NIF reached a real scientific milestone (scientific is the keyword there), and First Light and HB11 look promising, but commercially viable fusion remains elusive… at least for now. But it’s not all doom and gloom, there are real reasons to be optimistic about fusion’s future.

As we touched on earlier, arguably NIF’s single biggest issue is its reliance on incredibly powerful, but still energetically inefficient lasers. So, it’s worth noting that laser technology has advanced over the last 10 years. Lawrence Livermore National Laboratory officials even stated that NIF is using laser tech from the 80s, and modern lasers can be up to 20% more efficient.¹⁵ That doesn’t make up for the incredible energy deficit, but there is progress being made. It’s probable that if there isn’t another big fusion advancement on the horizon, there might be a laser advancement that could increase the efficiency of ICF reactors like NIF and finally make them truly energy positive.

Then there’s First Light Fusion’s projectile-based ICF. Though it hasn’t generated the net positive energy of NIF, after ‘bullet-proofing’ their process last April First Light has set their sights on a 2024 fusion demonstration. Given the history of fusion a 2024 or even 2025 demonstration might seem overly optimistic, but their confidence seems well-founded, and if all goes according to plan, they’ll be running a projectile fusion plant sometime in the 2030’s.¹⁶ I had a chance to talk to First Light Fusion and to say they’re being very realistic and pragmatic on their timetable would be an understatement. They’re well aware of their challenges and the long road ahead. I’m looking forward to seeing how their tech progresses.

And they’re not alone, it seems the UK is betting big on fusion. Their Atomic Energy Authority is repurposing the West Burton coal plant in Nottinghamshire into a STEP fusion plant. Step stands for Spherical Tokamak for Energy Production.¹⁷ They’re not dissimilar from the tokamak reactors you might be more familiar with (the giant donut shaped reactor that contains hot plasma … and always makes me think of Homer Simpson), but the STEP reactor promises to be smaller, and it’s hypothesized that with its smaller size it’ll be easier for the magnets to maintain the conditions required for fusion, and to be more energy efficient.¹⁷ Concepts are due in 2024, and if all goes well then the STEP plant should open its doors in 2040.¹⁸ It’s similar for the Spark reactor coming from Commonwealth Fusion Systems that I’ve covered in a previous video.

Back to ICFs – HB11’s reactor is promising, but there’s still a lot of research and testing to be done on all its components. It’s not as far along developmentally as First light Fusion, which means there’s a very long way to go before commercialization is even an option. On the other hand, they’ve recently been awarded $20 million from Deakin University, as part the university’s plan to build “the largest recycling and clean energy advanced manufacturing ecosystem in Australia.”¹⁹ The experiments have been encouraging so far.¹³

Fusion energy has huge potential, but to date, we don’t have any commercial solutions, and we don’t know about costs, payback, or life cycle. Fusion is a highly complex challenge requiring substantial investment and research to make it feasible and cost-effective. That said, NIF’s breakthrough truly marks a major milestone in fusion technology, and years from now we may well be looking back on December of 2022 as the dawn of the fusion era. There’s also the wide gamut of labs and entrepreneurs that are trying a lot of unique approaches to fusion. I’ve previously explored many like Helion and General Fusion. It’s possible that one of these technologies really will be the way forward for commercially viable fusion. While fusion might not be right around the corner, like the next few years, the scope and frequency of recent advances means there’s good reason to be optimistic about a not-too-distant fusion future.