How close is nuclear fusion power?

It’s true that ITER will not produce net power and that the administrators have misled the public about the difference in Q factors. You can have a reactor which produces more thermal power than you put in to it that is still a net power drain when you factor in the rest of the plant operations to keep it going. All clearly explained in this great video. [this video] There is a real risk that by focusing on the wrong Q factor you sink all your budget in to plants which can never work as a real power plant. Still I am hopeful that ITER will be sufficiently valuable as a research system that we do move closer to commercial fusion power.

There is quite some misleading terminology being used in the field of nuclear fusion (see excellent overview here [1]). So I was genuinely curious what kind of Q is used in this paper, so here it is: > In this regime, self-heating from α-particle deposition exceeds the external heating input into the DT8; this ratio is denoted Qα, where the self-heating is taken relative to the heating power to the plasma—for inertial fusion this is the PdV compressional work on the fuel and not the total laser energy (P, pressure, dV, volume change). Qα > 1 is a burning plasma. So as far as I understand such Qα > 1 can be reached without sustaining neither pressure or volume, so one can think about it as an explosion rather that intuitive burning (somewhat continuous process). To summarize: Q_total = total_energy_out / total_energy_in is what matters, not any Q related to plasma energy. Since to build a power plant we just care what it consumes in comparison with what it produces. For this particular case even though Qα > 1 you likely can extract just a tiny fraction of that energy stored in plasma, while spending huge amounts of energy to heat it in the first place. 1. [this video] or as an article [link] Edit: I'm a big proponent of nuclear fission and fusion since both are the best (current and future) way of getting carbon neutral energy, which can cover the spikes in the grid and sun/wind-less days. It is just important to be careful with the terminology, which can be used to make research r

The question is, in terms of energy input, are we talking about Q-total or Q-plasma? Based on the video by Sabine Hossenfelder, my guess would be, the announcement references Q-plasma. That would mean that the announcement is a motte-and-baily miscommunication, as it promises much more than people are lead to read into it. Motte: We got more energy out than we put in. Bailey: Oh, what we really meant is, more energy was produced, than was put into the plasma, though we didn't actually capture any energy and also, there was actually a great deal of energy also needed to run all the ancillary systems to keep the plasma confined. How close is nuclear fusion power? [this video]