Another FUSION thread...

[Sarkus]

Well, seems that fusion power has inched a step closer... a Q of 1.54 has been reported by NIF (National Ignition Facillity), according to the news (e.g. here.

It's certainly an achievement - a Q > 1 means that it produces more energy than it uses from the ignition system. In this case roughly 2 MJ in produced roughly 3 MJ out.

Sounds impressive... and it is certainly a step forward (with previous best being c.0.7, I believe). BUT... and it's a big BUT... this is not the full picture.
This Q figure is known as the Q-scientific. It only takes into account the actual energy utilised within the ignition process, not all the waste energy due to engineering inefficiencies. To be of commercial viability (ignoring cost) it needs to produce more energy out than ALL the energy input into the system. This is known as Q-engineering, and Q-engineering will need to be in excess of 1. Ideally much higher.

Now, the reported Q of 1.54 was Q-scientific. An achievement for sure, but it's still far from commercially viable. The NIF reactor utilises laser tech from the 1980s, which unfortunately has an efficiency of c.1%. So in terms of Q-engineering we're at c.0.01 or so. I.e. it still requires c.100MJ of total energy in the system to produce c.1MJ output from the fusion. And that's possibly before all the other inefficiencies in the system beyond just the lasers.

More modern lasers are apparently c.20% efficient, so there's certainly some scope for improvement, and it's thought/hoped that the larger the reaction the far more efficient it actually becomes.

So it's a step in the right direction... and who knows, maybe Fusion is now only... what? 20 years (and many more billions/trillions in investment) away?

 

[billvon]

This Q figure is known as the Q-scientific. It only takes into account the actual energy utilised within the ignition process, not all the waste energy due to engineering inefficiencies.

In addition, that is HEAT energy out. Useful electrical energy is about 30-40% of that.

 

[Quantum Quack]

...might be appropriate to post here...
Published 14/12/2022 AEST

 

[Sarkus]

In addition, that is HEAT energy out. Useful electrical energy is about 30-40% of that.

Yup. Possibly not even that, but I'd just be guessing.

It'd be good if journalists and media outlets could be a bit more transparent on such things, especially the mass media that is focussed on Joe Public, as opposed to the trade/scientific media who might be more au fait with the nuances. I mean, when they start going on about how they were "producing more energy from a fusion experiment than was put in" it would suggest to the majority that they are referring to all the energy put in to the entire thing - i.e. how much the whole shebang is drawing from the grid, so to speak. They don't speak anywhere how this is true only in a rather limited sense, when you only consider a certain aspect of the whole setup, and that we are far from it being what Joe Public would consider as "breakeven".

Ah, well. 'Tis good news, though. Progress is better than nothing.

 

[exchemist]

Well, seems that fusion power has inched a step closer... a Q of 1.54 has been reported by NIF (National Ignition Facillity), according to the news (e.g. here.

It's certainly an achievement - a Q > 1 means that it produces more energy than it uses from the ignition system. In this case roughly 2 MJ in produced roughly 3 MJ out.

Sounds impressive... and it is certainly a step forward (with previous best being c.0.7, I believe). BUT... and it's a big BUT... this is not the full picture.
This Q figure is known as the Q-scientific. It only takes into account the actual energy utilised within the ignition process, not all the waste energy due to engineering inefficiencies. To be of commercial viability (ignoring cost) it needs to produce more energy out than ALL the energy input into the system. This is known as Q-engineering, and Q-engineering will need to be in excess of 1. Ideally much higher.

Now, the reported Q of 1.54 was Q-scientific. An achievement for sure, but it's still far from commercially viable. The NIF reactor utilises laser tech from the 1980s, which unfortunately has an efficiency of c.1%. So in terms of Q-engineering we're at c.0.01 or so. I.e. it still requires c.100MJ of total energy in the system to produce c.1MJ output from the fusion. And that's possibly before all the other inefficiencies in the system beyond just the lasers.

More modern lasers are apparently c.20% efficient, so there's certainly some scope for improvement, and it's thought/hoped that the larger the reaction the far more efficient it actually becomes.

So it's a step in the right direction... and who knows, maybe Fusion is now only... what? 20 years (and many more billions/trillions in investment) away?

My sentiments entirely, Doctor. Rather a lot of hype, considering the monstrous engineering challenges of turning this concept into a commercial power station, none of which have yet been addressed.

I think it must be still 30 years away. The tokamak approach is almost as far from reality, but that design looks a bit easier to envisage turning into a commercial reactor.

 

[foghorn]

Another FUSION thread...

Maybe a mod will fuse this thread with the other fusion threads.

 

[Sarkus]

My sentiments entirely, Doctor. Rather a lot of hype, considering the monstrous engineering challenges of turning this concept into a commercial power station, none of which have yet been addressed.

This piece is quite good: not a lot of jargon but sets out the hurdles, at least of the route this inertial fusion needs to take.

I think it must be still 30 years away. The tokamak approach is almost as far from reality, but that design looks a bit easier to envisage turning into a commercial reactor.

I'd say 50 to 100 for the NIF approach. It seems to take 10 years just to build the next iteration of reactor, and there'll need to be several more, I think. If ITER can achieve the 10-fold increase in thermal power as is hoped, then I think that will be the death-knell to the inertial fusion approach as anything other than a curious side-project; funding will gradually dry up for it as they put the full weight behind the magnetic confinement approach. If ITER does achieve it then maybe we're 40-50 years away, which I still think is optimistic. But I'm that sort of guy! (Really just wishful thinking in that I'd like to see it happen before I shuffle off this mortal coil )

 

[exchemist]

This piece is quite good: not a lot of jargon but sets out the hurdles, at least of the route this inertial fusion needs to take.

I'd say 50 to 100 for the NIF approach. It seems to take 10 years just to build the next iteration of reactor, and there'll need to be several more, I think. If ITER can achieve the 10-fold increase in thermal power as is hoped, then I think that will be the death-knell to the inertial fusion approach as anything other than a curious side-project; funding will gradually dry up for it as they put the full weight behind the magnetic confinement approach. If ITER does achieve it then maybe we're 40-50 years away, which I still think is optimistic. But I'm that sort of guy! (Really just wishful thinking in that I'd like to see it happen before I shuffle off this mortal coil )

Well I'm pushing 70, so it's not going to be in my lifetime, but for the sake of my son I hope it eventually succeeds. One of these two technologies is going to be Betamax and one will be VHS. In principle, the tokamak approach is more betamax, is it seems technically far more elegant than ICF. As the Betamax saga showed us, engineering and commercial muscle can have as much to do with the eventual outcome as technical elegance.