The Bizarre Reactor Scientists Hope Will Save Fusion Research (sciencemag.org)

sciencehabit writes: In a gleaming research lab in Germany's northeastern corner, researchers are preparing to switch on a fusion device called a stellarator, the largest ever built. The €1-billion machine, known as Wendelstein 7-X looks a bit like Han Solo's Millennium Falcon, towed in for repairs after a run-in with the Imperial fleet. Stellarators have long been dark horses in fusion energy research but the Dali-esque devices have many attributes that could make them much better prospects for a commercial fusion power plant than the more popular tokamaks: Once started, stellarators naturally purr along in a steady state and they are not prone to the potentially metal-bending magnetic disruptions that plague tokamaks. Unfortunately they are devilishly hard to build.

Comments

Re:Q: heat

[benjfowler]

Heating (and confinement) are now basically solved problems in magnetic confinement machines. The Wikipedia article says that they'll be using bog-standing microwave heating (they don't say exactly what), and neutral-beam heating in W-7X.

Both tokamaks and stellarators have to 'twist' the magnetic field around the torus (since paths around the inside of the torus are smaller than the outside, leading to instabilities). Tokamaks achieve this by inducing a current through the plasma to induce the twist in the magnetic field using a huge solenoid or other means; stellarators use external coils.

The former are prone to catastrophic disruptions (which in extreme cases, can unleash strong forces that could, in the absolute worst case, physically break the machine); the latter are more stable, but much harder to manufacture.

Re:Dat Title

[fisted]

Dat device tho.

Re:Even if ITER or W7X works, is it economical?

[Anonymous Coward]

The bullet points where you give numbers make no sense. 10000 tons of lithium? Design studies for DEMO, which would have several GW of thermal output, have a blanket volume on the order of 500 m^3. Even if assuming that was all lithium, you are talking about 300-400 tons, much smaller than 10000 tons. 10000 tons would be a block of lithium about 27 m on a side, which is much larger than the whole reactor vessel design.

Scaling the costs is very difficult to do. A production reactor would be far cheaper in many ways, because you don't need as much diagnostic access. A lot of compromises have to be made to just get enough space between the magnets of many designs for diagnostics, plus the costs of diagnostics (millions of dollars each for the many of them), plus the costs to use, maintain and analyse them. This is part of why designs for DEMO are only about 15% larger than ITER, but of a much more compact design considering it is producing nearly 4-8 times as much thermal output.

Re:DOE report says fusion is likely uneconomical

[angel'o'sphere]

Wind and solar will never compete with coal and fission.
But actually they do. In Germany coal planets get decomissioned because they can no longer compete.
Part of this is because wind and solar require viable (read that as cheap, reliable, etc) storage to provide 24/7 power
That is nonsense, as no country is running 24/7 with "full power", power is a curve with a lower bottom at somewhere between 40% and 60% of your peaks during daytime.

A big problem with any power plant that works by steam power, which coal and fission do, is that it does not respond well to large daily swings in power demands. That is wrong. A coal plant adjusts to demand in a few minutes.

the most popular one because it is cheap is natural gas turbines.
That is double wrong. The most popular is pumped storage, because it is cheap and the secondary one is gas turbines because gas turbines are horrible expensive, however nearly as fast in reaction as pumped storage.

fission it is still the cheapest solution we have That is again wrong, in most countries fission power is the most expensive power.

Wind and solar can only operate with something like 30% up time.
That is wrong. Wind plants have a very high uptime, and build at suitable places a very high CF, too. Solar PV plants run with the sun. Solar thermal plants with molten salt storages run around the clock. With their peak around the daily peaks and at roughly 60% at night when demand is low.

Storage is overrated. Storage becomes usefull, when you are far above 50% renewables, approaching lets say 75%. With 50% "baseload", you had 25% surplus at night, which you could store and use at daytime (to have 75% + 25% = 100%) The point where storage becomes interestnig depends on where your baseload line in relation to your peak is. Or what you can distribute in your grid.
And ofc. you would basically only store energy from baseload plants or from renewables. Storing energy from gas turbines makes no sense as a gas turbine gos from zero to 90% load in 30 seconds and is on 100% load in roughly a minute. Storing energy from coal or fission akes no sense either (unless you refill a pumped storage ... because you will need it the other day, but for that you prefer a baseload plant at night)

Instead of sitting in the corner of your room and dreaming up "facts" about energy production,you should read a bit about it.

Basically every claim you made or idea you had in your post: is wrong

Re:DOE report says fusion is likely uneconomical

[Zak3056]

Wind and solar will never compete with coal and fission.
But actually they do. In Germany coal planets get decomissioned because they can no longer compete.

The reason that coal is not competitive in Germany is because the playing field is severely tilted in favor of wind (wind power gets a premium price that is, IIRC, funded by fossil, and also has priority in the grid. If there is renewable available, the fossil plans have to spin down). That climate makes it absolutely uneconomical to run a large powerplant that is slow to respond to changes in supply and demand.

Please note that I'm not saying this is necessarily a bad thing (though some of my German colleagues think the situation is untenable for various reasons), but your argument above is not nearly as simple as you frame it.