Historical First: Inside the National Ignition Facility, where last week 192 laser beams blasted a hydrogen fuel pellet, which emitted more energy than it took in.
Lawrence Livermore National Laboratory
Nuclear fusion has long been the Holy Grail of truly clean energy. The smashing together of hydrogen atoms promises limitless electricity with zero carbon emissions, a minimum of radioactive waste and zero chance of catastrophic meltdown. But for a half-century fusion scientists have been limited by the power of their lasers and the strength of their magnetic fields — never before figuring out how to milk more energy out of their atom smashing than they put in. Until now.
Today scientists at the National Ignition Facility at the Lawrence Livermore National Laboratory (LLNL) in California will reveal that in early December, for the first time, they have managed to achieve energy gain of greater than 1 — that is, more energy was emitted from the reactions inside their deuterium-tritium fuel capsule (2,000 megajoules) than was contained in the 192 lasers that they blasted it with.
It’s a big deal, worth celebrating, but somewhat of a foregone conclusion, says Debra Callahan, a plasma physicist who recently left the LLNL fusion team to become scientific director at startup Focused Energy, which is already working to commercialize the approach.
Callahan knew LLNL would achieve net energy gain after last year they reached an energy output of 72% of their laser energy inputs. “It’s not a surprise to me. Given the path of results we had been seeing, it was going to happen,” she says. They just needed slightly more laser power. So how does it work? Imagine a little hollow cylinder made of gold that fits in the palm of your hand. That’s called the hohlraum. Inside the hohlraum goes a tiny fuel capsule inside of which are deuterium and tritium atoms.
They use gold because it holds in the x-rays that are produced when they blast either end of the hohlraum with 173 of the world’s most powerful lasers. Callahan says, “It’s like an x-ray oven,” which compresses the fuel so much that it implodes and ignites fusion among atoms at the center of the capsule. The fusion then propagates out in a wave from the center, emitting prodigious heat. All this happens in a billionth of a second.
In the inertial confinement approach to fusion, laser beams blast a pellet containing hydrogen isotopes, igniting a fusion reaction.
Focused Energy
Why did Callahan leave LLNL when they were on the cusp of success? Because, she says, the National Ignition Facility is not a fusion machine. The hohlraum is great for demonstrating ignition, but it’s not necessarily efficient enough for engineering continuous pulsed fusion because so much residual laser energy is lost in heating up the gold rather than the hydrogen fuel. So at Focused Energy (backed by Prime Movers Lab and New Enterprise Associates) their plan is to discard the hohlraum and instead use a “direct drive” approach — blasting the lasers directly onto a fuel capsule (see schematic).
They haven’t yet demonstrated that it works, but Callahan is confident that in a couple years their pilot project will achieve a 10x energy gain. That will be followed by a second plant reaching 30x gain, followed by what at the end of the 2030s would be their first commercial generator, hopefully achieving a 100x energy gain and blasting 10 fuel capsules every second.
But therein lay a particular challenge. At 10 per second, their machine would use nearly 900,000 capsules per day. This ain’t like shoveling coal into a furnace; each capsule would need to be manufactured to exacting standards and shot into the machine with perfect timing.
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Is that realistic? Some fusion competitors don’t think so. General Fusion is a Vancouver, Canada-based fusion company that yesterday announced its own milestone. Its approach is called magnetized target fusion and involves a machine where they inject a ball of hydrogen plasma into the machine and use powerful magnets to hold it while compressing with mechanical pistons rather than lasers. CEO Greg Twinney expects the pilot plant General Fusion is building in the U.K. to demonstrate fusion in 2027, with commercial design ready in the early 2030s. “When we see news like this we’re not surprised,” he says. But the LLNL’s approach can’t be extrapolated into a working fusion plant, which is what General Fusion (backed by $300 million from Jeff Bezos, Shopify
Prototype machine under development by Vancouver-based General Fusion.
General Fusion
The LLNL news generated a similar response from CEO David Kirtley of Seattle-based fusion startup Helion, backed by $600 million from tech tycoons Peter Thiel, Sam Altman, Dustin Moskovitz, Reid Hoffman and Jeff Skoll. “We are excited that they hit their science milestones for their machine,” Kirtley says. But he doesn’t feel threatened by “a research device not designed to make electricity.” By contrast, the operation of Helion’s 60-foot-long fusion machine involves injecting plasma balls at each end, smashing them together in a 100 million degree reaction controlled by intense magnetic fields. In Helion’s novel system, the energy released in the fusion reactions continuously pushes out against its magnetic containment field, which pushes back — causing oscillations “like a piston,” says Kirtley, that generate an electric current, which Helion captures directly from the reactor. (For more, read up on Faraday’s law of induction.)
Helion is building its 7th prototype and designing its 8th, which Kirtley hopes will be the first commercial fusion generator — possibly connected to the power grid by the end of this decade, if all goes right. He says federal nuclear regulators look set to subject their machine to the same rules as particle accelerators and the kind of imaging machines used at hospitals.
And there are plenty of other companies pursuing the most established approach to fusion — the tokamak concept, in which balls of plasma are injected into a reactor chamber shaped like a hollow donut, controlled by powerful magnetic fields. Commonwealth Fusion, an MIT spinoff, is seeking to perfect the tokamak using ultra high temperature superconducting materials that CEO Bob Mumgaard thinks will enable them to have a working fusion device by the end of the decade. Same goes for San Diego-based General Atomics (best known for inventing the Predator drone), which has been operating a tokamak for the Department of Energy for decades and is designing a new machine. G.A. also built arguably the world’s most powerful magnet, called the central solenoid, for the world’s biggest fusion project of all, the $30 billion ITER under construction in France. If the other fusion startups have their way ITER will be obsolete before it’s even completed sometime next decade. Spreading its bets, G.A. (owned by billionaire Neal Blue) has a partnership with the Savannah River National Lab to manufacture fuel pellets for laser-based fusion machines like LLNR and Focused Energy.
The tokamak approach to magentic fusion involves a reactor shaped like a hollow donut surrounded by powerful magnets.
Focused Energy
Whoever you talk to in the fusion field, their criticisms of long established nuclear fission reactors are the same. Fission reactions (in which big atoms of enriched uranium are broken apart) yield radioactive waste including plutonium and dangerous actinides that can be weaponized. Unlike fusion, which is hard to start and easy to stop, fission reactions are easy to start and hard to stop, introducing the risk of catastrophic meltdowns. Newer designs, like the Westinghouse AP1000 fission reactor, under construction in both the U.S. and China, feature passive safety measures and are virtually meltdown proof.
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Some atomic entrepreneurs think fission is sufficient. Bret Kugelmass, founder and CEO of Last Energy, set out five years ago to devise the world’s most efficient and economical nuclear reactor. Before settling on his approach, Kugelmass, now 36, interviewed hundreds of nuclear industry experts (and put the talks on his Titans of Nuclear podcast) to glean the industry’s collective wisdom. Though he has faith in the long-term future of fusion, Kugelmass determined that the world’s best bet for transitioning away from fossil fuels lay in building modular fission reactors in the simplest, cheapest, safest way possible. At its factory near Houston, Last Energy is now manufacturing its first small, modular pressurized water reactors, which utilize off-the-shelf components, sourced via existing nuclear supply chains, with technology that has been perfected over the decades and is used in more than 300 reactors worldwide.
Already, Last Energy has sold 10 of its 20-megawatt units to a customer in Poland, two more for Romania, and a handful for Britain. Kugelmass says his intellectual property isn’t in the proven components, but in how to put them all together. He’s so far raised $24 million led by Gigafund, and expects the first reactors in Poland to be running in 2025. To finance the machines, Last Energy enters into long-term power purchase agreements promising customers decades of zero-carbon nuclear power at below market prices. “We were able to carve off a desirable niche that nobody was going after,” says Kugelmass. “We black boxed the entire operation.”
As alluring as the fusion promise may be, if Kugelmass has his way the competitive realities of established, reliable fission could yet relegate its hip new cousin to the dustbin of heroic tech flops — remember Betamax, Google Glass and New Coke?
Source: https://www.forbes.com/sites/christopherhelman/2022/12/13/national-lab-unlocks-nuclear-fusion—true-breakthrough-novelty-act-or-both/