[simonh]

A lot of the recent Fusion startups seem to be making worryingly unrealistic claims that make me somewhat skeptical.

Whenever they talk about putting a fusion reactor in a shipping container, or on the back of a truck that's a red flag. Any fusion plant capable of useful power output is going to have to kick out enough neutron radiation to need some pretty serious shielding that just makes that impossible.

Another problem is the way they often pitch the energy gain numbers. Q=1 sounds great, the output energy equals the input energy, but that's only the input energy required to maintain the plasma. The actual energy to power the plant and run the heat exchange system and such as a whole (Engineering Gain = 1) is likely to be about 22x that. Then to be economically viable in practice the gain might need to be an order of magnitude or more again.