Good question - as far as I can tell, the article doesn't say so explicitly, so I assume it's not generating a surplus, since if it did, that would have been th

Good question - as far as I can tell, the article doesn't say so explicitly, so I assume it's not generating a surplus, since if it did, that would have been the headline. There is however the possibility that the two interesting numbers, required power input and power output, do not grow with the size of the reactor/amount of plasma in the same way, e.g. one function might be quadratic, the other cubic. So it is possible that the current prototype does not generate a surplus, but it might indicate enough about those two functions to indicate that a "slightly" larger version would (assuming no unforeseen technical or physical issues arise). It sounds like it's too early to say though.