> It is designed to achieve a Q factor — a key parameter denoting the efficiency of a fusion plasma — of at least 2, essentially meaning that twice as much fusion energy is produced as the amount of energy pumped in to generate the reaction. That would be the first time a fusion plasma of any kind has produced more energy than it consumed.
I didn't realize until recently that such statements from physics researchers have to be read very carefully. These aren't statements about the actual net power output of a theoretical power station, even though they read that way. They "define out" huge power draws that are physically necessary.
The MIT PR is hardly better than the MSN article in this regard. The subhead says it "paves the way for practical, commercial, carbon-free power". They've done no such thing. The challenges faced by a real power plant are still far larger than usually gets reported.
The biggest practical challenge facing fusion isn't even generating sufficient power or being cheap enough, IMO. It's that it's still nuclear technology and the claims about it being "clean" are invariably only talking about carbon (and ignoring the CO2 in the construction). The operation of the plasma irradiates the power plant itself and generates large quantities of low-grade nuclear waste that must still be buried somewhere. It's not as dangerous as the stuff from fission but there'd be more of it, it can still leak causing biohazards, and you still need scary stuff like robots to work with the reactor. Fusion plants also need to be really big to be practical, and they would consume way more water as a consequence.
Given that the Greens have been shutting down nuclear plants due to general fear of nuclear technology, would something that looks just like it get a free pass? Despite the radioactive waste problem, the water consumption, the need for huge subsidies?
There's also the issue of where to get tritium for reactor designs that need it. You have to get it from fission reactors! In theory it can be recycled but the practical challenges for that are themselves enormous.