Fusion breakthrough thrills physicists, but won’t power your home soon

A reported breakthrough in fusion energy is generating enormous excitement amongst scientists and the general public alike — but you might not want to bet on fusion providing usable energy during your lifetime. 

Experimental results set to be announced by the U.S. Department of Energy on Tuesday are being hyped as potentially heralding a new era of zero-carbon energy from the power of a controlled fusion reaction, the same reaction that powers our sun. 

Lawrence Livermore National Laboratory has evidence of a net energy gain in a fusion reaction for the first time, according to people with knowledge of preliminary results from a recent experiment, as first reported by the Financial Times. The lab confirmed to the paper that a successful experiment had recently been conducted at its National Ignition Facility but said analysis of the results was ongoing. 

For 70 years, physicists have tried to get more energy out of a fusion reaction than it took to create the reaction — a net energy gain. Government research labs and, more recently, privately funded startups have attempted to unlock this theorized but unproven power of the atom. This is the first time anyone appears to have succeeded. 

This could truly be a breakthrough, but there are still a lot of ​“ifs”:

• If the math and measurement works.
• If the experiment is repeatable and controllable.
• If the energy from the reaction can be efficiently transformed into usable power. 
• If the tritium fuel can be obtained in sufficient quantities.
• If there is an economic pathway to commercialize the technology. 

That’s a lot of uncertainty to be overcome before this development could lead to clean grid energy at scale. 

Lasers vs. magnets

The National Ignition Facility at Lawrence Livermore Lab is a laser-based inertial confinement fusion research machine that focuses 192 ginormous laser beams onto a pea-sized hydrogen fuel target for a few billionths of a second. These high-powered lasers combine to ignite the fuel pellet and create a contained plasma reaction. 

Most of the venture-capital funding of fusion startups has gone toward companies trying to use different methods of producing a reaction — primarily magnetic confinement of the plasma, where the plasma is stabilized by massive magnets and heated to extraordinary temperatures so the nuclei can fuse. Fusion startups such as Avalanche Energy, Commonwealth Fusion, Helion Energy, TAE Technologies and Zap Energy have won more than $4 billion in venture funding in the last few years as investors such as Bill Gates and Jeff Bezos have become intrigued with the technology. 

According to the Financial Times, the fusion reaction at the U.S. lab produced about 2.5 megajoules of energy, about 120 percent of the 2.1 megajoules of energy in the lasers. Two sources with knowledge of the results said the net energy gain had been greater than expected.

Again, if verified, this means scientists have gotten out more energy from the plasma than they applied. It means we have achieved ​“ignition,” and that’s a big deal.

Hype vs. reality

Chanda Prescod-Weinstein, an assistant professor of physics at the University of New Hampshire, wrote on Twitter that the reported breakthrough is a ​“huge technical achievement,” but then she tempers enthusiasm by noting that it’s ​“not obvious it will lead to energy production even in decades.” And she points out that while there’s a net energy gain in one key sense, the project is far from achieving a net energy gain overall:

She warns: ​“press gonna oversell.” Keep that in mind if you’re seeing overheated enthusiasm in your news feed. 

Bottom line: This is a big deal if you’re a fusion scientist and not of practical relevance if you’re a grid operator.