Alex McColgan

which upon absorbing a neutron, helpfully decays into a helium atom and tritium.

However, as ever in fusion, this solution comes with its own problem.

If each deuterium-tritium fusion reaction generates one neutron, which via lithium can be used to generate one new tritium, you would need to operate at an impossible 100% efficiency to prevent your tritium supply from dwindling.

The answer most fusion researchers favour is to add layers of other elements like beryllium that can act as neutron multipliers, absorbing one neutron and spitting out two.

But not only is beryllium toxic, it is also in short supply, and contaminated with uranium, which then bombarded with neutrons,

leads to radioactive byproducts, less than ideal.

And regardless, there are concerns that even with breeding, most reactors would struggle to generate enough tritium to be viable.

So, at this point, you might be thinking, hang on a minute.

It seems a lot of the touted advantages of fusion, bountiful energy, plentiful starting materials, innocuous, if even useful byproducts, are kind of falling away.

Well, you'd be right.

We're not fusing hydrogen, or at least the same isotopes of hydrogen that the star fuses, and we're not making just helium, but a bunch of other radioactive products as well.

The simple truth, no matter what the headlines say, is that we can't make a star on Earth.

And the shortcuts to create something approximating one create a world of engineering challenges.

This is why, since the first fusion reactor patent was granted in 1946, fusion has always seemed just out of reach.

Each solution comes with a new set of problems.

But not all hope is lost.

In recent years, things do seem to be changing, with some hugely significant science breakthroughs.

In December 2022, for the first time ever, more energy was obtained from a fusion reaction than was required to initiate it.

a challenge that had eluded researchers for decades.

At the National Ignition Facility, a research-scale ICF reactor in the US, 3.15 MJ of energy was obtained from a tiny pellet of DT fuel, using an energy input of 2.05 MJ.