Magnets are used in medicine, industry, electronics, and even high-speed trains. Now, a new kind of magnet may help unlock the clean energy of the future.

At MIT, a spin-out company called Commonwealth Fusion Systems is building a magnet that could change the way the world makes energy.

The key is a 20-tesla high-temperature superconducting magnet, the strongest of its kind. This magnet is powerful enough to hold in place a swirling plasma hotter than the core of the Sun. Inside that plasma, hydrogen atoms can fuse together, the same process that powers stars.

The company’s first reactor, SPARC, is under construction now and is expected to show net energy gain as early as 2027.

If fusion can be harnessed, it would mean clean, safe, and virtually limitless energy. Fusion runs on abundant hydrogen, produces no greenhouse gases, and leaves no long-lived radioactive waste. Thanks to magnets like these, the dream of “bottling a star” to power our homes may finally be within reach.