I’ve seen more news on fusion power generation lately. Among the various claims, a company in Britain seems to think they can run D-T fusion in a tokamak as small as 1.5 meters.

I doubt it. I really doubt it.

D-T is almost certainly what we will use on earth and, perhaps, the moon, and D-T produces material-damaging 14 MeV neutrons. The neutrons also activate the materials, meaning the entire power unit becomes radioactive waste.

A sufficiently small D-T unit may be able to run longer because it will have low structural requirements, but the neutrons embrittle the materials such that the steel (or other material) walls become easy to break, like glass. At some point, the power unit is not structurally sound. It becomes unsafe and must be decommissioned, dismantled, and disposed of as radioactive waste–all of it.

Fusion power of some sort will be the only significant source of power at some point in humanity’s future, but it is not clean and not limitless. That mostly means it will always be expensive with high engineering requirements. It has very significant engineering and safety challenges, including environmental impacts. Granted, most of these challenges are likely to be easier to deal with than other power options, but it is simply false and misleading to suggest that fusion will be clean and inexhaustible.

We will burn fossil fuels for the foreseeable future. (The alternative is mass murder on the order of a billion people.) Nuclear fission will dominate in coming decades, for decades, perhaps for a century or two, then fusion. Once fusion is working, and we overcome the startup and growing pains, then it will be the only significant source of our energy needs for as long as humans do what humans do. I just happen to think generations of us will pass from this earth before the first gigawatt-hour of consumer-electricity is generated by fusion power reactors.