I’ve been following them since they were giving promising lectures at MIT and I absolutely think they have the most solid approach! Tokamaks are well understood, they supposedly have the same plasma physics as ITER which has been heavily scrutinized and supported by work at JET, and their concept is simple - Tokamak but with very high field superconducting magnets using technology that wasn’t available when ITER was conceived, and apparently higher field strengths mean a smaller reactor for the same power gains. As a lay person the story is simple and that’s good! Then they demonstrated their magnets and got $2B in funding and now they’re deep in the construction phase for SPARC.

I encourage anyone curious to look up videos on SPARC on YouTube. It’s very encouraging! It seems honestly very reasonable that they will see sustained net energy gain for their entire power plant before 2030 (tho SPARC is still a demonstrator not designed for continuous service, so “sustained” means like one minute).

Here’s some videos:

8 years ago:

https://youtu.be/KkpqA8yG9T4

2 years ago:

https://youtu.be/KkpqA8yG9T4

Latest update posted yesterday:

https://youtu.be/w3Giq6NuPYs