Welcome to Zero. I am Akshadrati. This week, a different kind of solar power.

Nuclear fusion is a reality. It's how the Sun produces energy.

But trying to replicate what the Sun does here on Earth has been, to put it mildly, a challenge.

For a long time, nuclear fusion as an energy source has been in the realm of science fiction. One can imagine powering civilizations that move

across planets and maybe even galaxies. But bringing it back down to Earth, to our current

climate predicament, fusion power could also provide emissions-free unlimited energy, and wouldn't that be nice?

Fortunately, after more than 50 years of trying, there is some success to report on.

In fleeting experiments, scientists have been able to generate more energy from fusion reactions

than the energy put into making them happen in the first place.

Now, someone just needs to do it at scale.

And there are dozens of startups trying to do just that.

One of the most promising ones is CFS, or Commonwealth Fusion Systems.

The startup CEO Bob Mumgard began his work at MIT,

where he worked with researchers studying plasma science.

They designed a reactor called Spark,

which could become the first large-scale reactor that generates more energy than it consumes.

CFS has now raised more than $2 billion in venture capital.

That's more than any other fusion startup.

Clearly, investors are betting that if CFS succeeds, there's a big return to be made.

How exactly?

Well, to find out, I caught up with Bob at the Breakthrough Energy Summit in June.

We nerded out about the science behind fusion, how CFS's bagel-shaped reactor, or Tokomac,

...