2021 state of the horse race: ITER vs. dark horses

[Giorgio]

Anyone understand how they get to that number?

Rough Numbers:
Fusion output: 1200 MWth.
From the PDF I sent you some days before at page 4 :
ETAe= 0.9 ETAcdc= 0.7 ETAddc= 0.85 ETAth= 0.45
So the electrical efficiency for the conversion is estimated at 45% or 540 MWe, and te expected Q is 5-8, so the injected power is between 150 to 240 MWe, and the average is around 190 Mwe. Remove this from 540 and you get the 350 MWe of the pdf you linked.

[Giorgio]

How can 1,200 MWth be "low value heat"?

The thermal load will be roughly 50% of that, so around 600MWth distributed more or less over all the machine. Also according the PDF they are expecting a peak heat flux of 1 to 2 MWth/m2 (or 100 to 200 W/cm2). Making a high pressure steam recovery system over all the 80 meters of the machine seems quite a challenging engineering issue. My guess is that they made no mention of a thermal recovery cycle because with such a low heat flux (and wide surface) it makes more economic sense to quickly remove the heat with a cooling fluid and limit the temperature stress over the machine.
Even if you recover all of the heat as a working fluid you can probably get out roughly 40% as electric power (after removing all ancillaries and equipment), so an extra 240 MWe. It does not look really economical if you consider the added capital costs and complexity.

[mvanwink5]

The problem with peakers is thermal cycling. The problem with solar is low power density, the need for storage, no support for heavy industry which is a 24hr operation. Wind has fatal weather issues, Germany, England, Texas can attest to that.

There were cost numbers for GF a long time ago and given that their machine design, that has not changed. It is a drop in retrofit to existing thermal steam plant boiler island.

I suspect that all fusion plants will look similar once the auxiliary systems are added in. Everything has trade offs. ITER looks dead commercially.

The break point is when utilities finally realize fusion is the future. Solar cannot work for China and India, think about a city with 50 million people, hydroponic farms operating in winter.

It will be tough to say whose machine will dominate, at least for me, but to tell the truth, I don't really care.

[Skipjack]

How can 1,200 MWth be "low value heat"?

The thermal load will be roughly 50% of that, so around 600MWth distributed more or less over all the machine. Also according the PDF they are expecting a peak heat flux of 1 to 2 MWth/m2 (or 100 to 200 W/cm2). Making a high pressure steam recovery system over all the 80 meters of the machine seems quite a challenging engineering issue. My guess is that they made no mention of a thermal recovery cycle because with such a low heat flux (and wide surface) it makes more economic sense to quickly remove the heat with a cooling fluid and limit the temperature stress over the machine.
Even if you recover all of the heat as a working fluid you can probably get out roughly 40% as electric power (after removing all ancillaries and equipment), so an extra 240 MWe. It does not look really economical if you consider the added capital costs and complexity.

You are probably right about that. It might not be worth the effort in the end.

[Skipjack]

I suspect that all fusion plants will look similar once the auxiliary systems are added in. Everything has trade offs. ITER looks dead commercially.

I think that depends on the reactor design and fuel etc. Some (ZAP, Helion, LPPF, am I missing somone?) could be quite a bit smaller than others and some of them will even have direct conversion. So they might be in a building as small as a large single family home or small warehouse.
The smaller the reactor, the lower the overnight cost, which reduces risks for investors and makes it viable for more than just large utilities.
TAE is certainly on the bigger side. 80 meters in length for the reactor vessel alone is approaching ITER- like dimensions, though simpler geometry and overall simpler design still result in a smaller footprint for the whole facility. It is still seems big to me.
Helion's reactor is supposed to be about 20 meters in length and just 2 meters tall. So quite a bit smaller. It also produces less power, though.
ZAP's reactor core is tiny at just some 2 meters or so in diameter and height (including the Lithium- Lead tank around it). They will need a steam power plant though, will that comes with that. The smallest and most compact I have seen so far would be LPPF. Question is whether they can get it to work (though to be fair that question applies to everyone).
I agree that ITER sized Tokamaks won't lead to anything that is commercially viable. The entire facility would be big and expensive. Tritium inventory for startup will be a serious problem (compare the numbers in the CFS presentation that I just posted!). So the overnight costs will be huge and that will mean a huge risk. The ITER-style Tokamaks better hope that Helion's design works. So that there will be more Tritium on the market for them to buy