Fusion achieves net energy gain (ignition)

The international fusion megaproject ITER. (Image)

On December 5, 2022, the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory achieved fusion ignition, producing 3.15 megajoules of fusion energy from 2.05 megajoules of laser energy delivered to the target. It was the first time a fusion experiment released more energy than it took to ignite the fuel. NIF has since repeated and improved on the result.

That is scientific gain, not engineering gain: NIF’s lasers draw far more energy from the grid than the fuel returns. The next milestone is a private company demonstrating Q > 1 in a machine designed to lead to a power plant. Commonwealth Fusion Systems is building SPARC, a compact tokamak using high-temperature superconducting magnets, and is targeting net energy around 2027. Portfolio company Focused Energy is pursuing laser-driven fusion aimed at commercial power.

Note that there are many definitions of net energy gain! “Target gain” compares fusion output with the energy delivered to the fuel; “wall-plug” or engineering gain compares it with all the energy the facility consumes. Commercial power requires the latter, so it’s important to consider how the energy gain was calculated.